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Sample records for enhanced single base

  1. Enhanced power quality based single phase photovoltaic distributed generation system

    NASA Astrophysics Data System (ADS)

    Panda, Aurobinda; Pathak, M. K.; Srivastava, S. P.

    2016-08-01

    This article presents a novel control strategy for a 1-ϕ 2-level grid-tie photovoltaic (PV) inverter to enhance the power quality (PQ) of a PV distributed generation (PVDG) system. The objective is to obtain the maximum benefits from the grid-tie PV inverter by introducing current harmonics as well as reactive power compensation schemes in its control strategy, thereby controlling the PV inverter to achieve multiple functions in the PVDG system such as: (1) active power flow control between the PV inverter and the grid, (2) reactive power compensation, and (3) grid current harmonics compensation. A PQ enhancement controller (PQEC) has been designed to achieve the aforementioned objectives. The issue of underutilisation of the PV inverter in nighttime has also been addressed in this article and for the optimal use of the system; the PV inverter is used as a shunt active power filter in nighttime. A prototype model of the proposed system is developed in the laboratory, to validate the effectiveness of the control scheme, and is tested with the help of the dSPACE DS1104 platform.

  2. A single-device universal logic gate based on a magnetically enhanced memristor.

    PubMed

    Prezioso, Mirko; Riminucci, Alberto; Graziosi, Patrizio; Bergenti, Ilaria; Rakshit, Rajib; Cecchini, Raimondo; Vianelli, Anna; Borgatti, Francesco; Haag, Norman; Willis, M; Drew, Alan J; Gillin, William P; Dediu, Valentin A

    2013-01-25

    Memristors are one of the most promising candidates for future information and communications technology (ICT) architectures. Two experimental proofs of concept are presented based on the intermixing of spintronic and memristive effects into a single device, a magnetically enhanced memristor (MEM). By exploiting the interaction between the memristance and the giant magnetoresistance (GMR), a universal implication (IMP) logic gate based on a single MEM device is realized.

  3. Sorting of Single Biomolecules based on Fourier Polar Representation of Surface Enhanced Raman Spectra

    NASA Astrophysics Data System (ADS)

    Leray, Aymeric; Brulé, Thibault; Buret, Mickael; Colas Des Francs, Gérard; Bouhelier, Alexandre; Dereux, Alain; Finot, Eric

    2016-02-01

    Surface enhanced Raman scattering (SERS) spectroscopy becomes increasingly used in biosensors for its capacity to detect and identify single molecules. In practice, a large number of SERS spectra are acquired and reliable ranking methods are thus essential for analysing all these data. Supervised classification strategies, which are the most effective methods, are usually applied but they require pre-determined models or classes. In this work, we propose to sort SERS spectra in unknown groups with an alternative strategy called Fourier polar representation. This non-fitting method based on simple Fourier sine and cosine transforms produces a fast and graphical representation for sorting SERS spectra with quantitative information. The reliability of this method was first investigated theoretically and numerically. Then, its performances were tested on two concrete biological examples: first with single amino-acid molecule (cysteine) and then with a mixture of three distinct odorous molecules. The benefits of this Fourier polar representation were highlighted and compared to the well-established statistical principal component analysis method.

  4. Sorting of Single Biomolecules based on Fourier Polar Representation of Surface Enhanced Raman Spectra

    PubMed Central

    Leray, Aymeric; Brulé, Thibault; Buret, Mickael; Colas des Francs, Gérard; Bouhelier, Alexandre; Dereux, Alain; Finot, Eric

    2016-01-01

    Surface enhanced Raman scattering (SERS) spectroscopy becomes increasingly used in biosensors for its capacity to detect and identify single molecules. In practice, a large number of SERS spectra are acquired and reliable ranking methods are thus essential for analysing all these data. Supervised classification strategies, which are the most effective methods, are usually applied but they require pre-determined models or classes. In this work, we propose to sort SERS spectra in unknown groups with an alternative strategy called Fourier polar representation. This non-fitting method based on simple Fourier sine and cosine transforms produces a fast and graphical representation for sorting SERS spectra with quantitative information. The reliability of this method was first investigated theoretically and numerically. Then, its performances were tested on two concrete biological examples: first with single amino-acid molecule (cysteine) and then with a mixture of three distinct odorous molecules. The benefits of this Fourier polar representation were highlighted and compared to the well-established statistical principal component analysis method. PMID:26833130

  5. Single-Phase, Turbulent Heat-Transfer Friction-Factor Data Base Flow Enhanced Tb

    1994-01-21

    Heat-exchanger designers need to know what type of performance improvement can be obtained before they will consider enhanced tubes. In particular, they need access to the heat-transfer coefficients and friction-factor values of enhanced tube types that are commercially available. To compile these data from the numerous publications and reports in the open literature is a formidable task that can discourage the designer from using them. A computer program that contains a comprehensive data base withmore » a search feature would be a handy tool for the designer to obtain an estimate of the performance improvement that can be obtained with a particular enhanced tube geometry. In addition, it would be a valuable tool for researchers who are developing and/or validating new prediction methods. This computer program can be used to obtain friction-factor and/or heat-transfer data for a broad range of internally enhanced tube geometries with forced-convective turbulent flow. The program has search features; that is the user can select data for tubes with a particular enhancement geometry range or data obtained from a particular source or publication. The friction factor data base contains nearly 5,000 points and the heat-transfer data base contains more than 4,700 points. About 360 different tube geometries are included from the 36 different sources. Data for tubes with similar geometries and the same and/or different types can be easily extracted with the sort feature of this data base and compared. Users of the program are heat-exchanger designers, enhanced tubing suppliers, and research organizations or academia who are developing or validating prediction methods.« less

  6. Single underwater image enhancement based on color cast removal and visibility restoration

    NASA Astrophysics Data System (ADS)

    Li, Chongyi; Guo, Jichang; Wang, Bo; Cong, Runmin; Zhang, Yan; Wang, Jian

    2016-05-01

    Images taken under underwater condition usually have color cast and serious loss of contrast and visibility. Degraded underwater images are inconvenient for observation and analysis. In order to address these problems, an underwater image-enhancement method is proposed. A simple yet effective underwater image color cast removal algorithm is first presented based on the optimization theory. Then, based on the minimum information loss principle and inherent relationship of medium transmission maps of three color channels in an underwater image, an effective visibility restoration algorithm is proposed to recover visibility, contrast, and natural appearance of degraded underwater images. To evaluate the performance of the proposed method, qualitative comparison, quantitative comparison, and color accuracy test are conducted. Experimental results demonstrate that the proposed method can effectively remove color cast, improve contrast and visibility, and recover natural appearance of degraded underwater images. Additionally, the proposed method is comparable to and even better than several state-of-the-art methods.

  7. Research on respiratory motion correction method based on liver contrast-enhanced ultrasound images of single mode

    NASA Astrophysics Data System (ADS)

    Zhang, Ji; Li, Tao; Zheng, Shiqiang; Li, Yiyong

    2015-03-01

    To reduce the effects of respiratory motion in the quantitative analysis based on liver contrast-enhanced ultrasound (CEUS) image sequencesof single mode. The image gating method and the iterative registration method using model image were adopted to register liver contrast-enhanced ultrasound image sequences of single mode. The feasibility of the proposed respiratory motion correction method was explored preliminarily using 10 hepatocellular carcinomas CEUS cases. The positions of the lesions in the time series of 2D ultrasound images after correction were visually evaluated. Before and after correction, the quality of the weighted sum of transit time (WSTT) parametric images were also compared, in terms of the accuracy and spatial resolution. For the corrected and uncorrected sequences, their mean deviation values (mDVs) of time-intensity curve (TIC) fitting derived from CEUS sequences were measured. After the correction, the positions of the lesions in the time series of 2D ultrasound images were almost invariant. In contrast, the lesions in the uncorrected images all shifted noticeably. The quality of the WSTT parametric maps derived from liver CEUS image sequences were improved more greatly. Moreover, the mDVs of TIC fitting derived from CEUS sequences after the correction decreased by an average of 48.48+/-42.15. The proposed correction method could improve the accuracy of quantitative analysis based on liver CEUS image sequences of single mode, which would help in enhancing the differential diagnosis efficiency of liver tumors.

  8. Development of a single aptamer-based surface enhanced Raman scattering method for rapid detection of multiple pesticides.

    PubMed

    Pang, Shintaro; Labuza, Theodore P; He, Lili

    2014-04-21

    The objective of this study was to develop a simple and rapid method that could detect and discriminate four specific pesticides (isocarbophos, omethoate, phorate, and profenofos) using a single aptamer-based capture procedure followed by Surface Enhanced Raman Spectroscopy (SERS). The aptamer is a single stranded DNA sequence that is specific to capture these four pesticides. The thiolated aptamer was conjugated onto silver (Ag) dendrites, a nanostructure that can enhance the Raman fingerprint of pesticides, through Ag-thiol bonds. It was then backfilled with 6-mercaptohexanol (MH) to prevent nonspecific binding. The modified SERS platform [Ag-(Ap + MH)] was then mixed with each pesticide solution (P) for 20 min. After capturing the pesticides, the Ag-(Ap + MH)-P complex was analyzed under a DXR Raman microscope and TQ Analyst software. The results show that the four pesticides can be captured and detected using principal component analysis based on their distinct fingerprint Raman peaks. The limits of detection (LODs) of isocarbophos, omethoate, phorate, and profenofos were 3.4 μM (1 ppm), 24 μM (5 ppm), 0.4 μM (0.1 ppm), and 14 μM (5 ppm) respectively. This method was also validated successfully in apple juice. These results demonstrated the super capacity of aptamer-based SERS in rapid detection and discrimination of multi-pesticides. This technique can be extended to detect a wide range of pesticides using specific aptamers. PMID:24551875

  9. Gold Nanoplate-Based 3D Hierarchical Microparticles: A Single Particle with High Surface-Enhanced Raman Scattering Enhancement.

    PubMed

    Ma, Ying; Yung, Lin-Yue Lanry

    2016-08-01

    Formation of intended nano- and microstructures with regular building blocks has attracted much attention because of their potential applications in the fields of optics, electronics, and catalysis. Herein, we report a novel strategy to spontaneously grow three-dimensional (3D) hierarchical cabbagelike microparticles (CLMPs) constructed by individual Au nanoplates. By reducing gold precursor to gold atoms, N-(3-amidino)-aniline (NAAN) itself was oxidized to form poly(N-(3-amidino)-aniline) (PNAAN), which specifically binds on Au(111) facet as a capping agent and which leads to the formation of gold nanoplates. Because of the incomplete coverage of Au(111) facet, new gold nanoplate growth sites were spontaneously generated from the crystal plane of existing Au nanoplates for the growth of other nanoplates. This process continued until the nanoplate density reached its maximum range, eventually resulting in CLMPs with well-controlled structures. This opens a new avenue to utilize the imperfection during nanoparticle (NP) growth for the construction of microstructures. The individual CLMP shows excellent surface-enhanced Raman scattering (SERS) performance with high enhancement factor (EF) and good reproducibility as it integrates the SERS enhancement effects of individual Au nanoplate and the nanogaps formed by the uniform and hierarchical structures. PMID:27452074

  10. Gold nanoaggregates for probing single-living cell based on surface-enhanced Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Lu, Peng; Wang, Jing; Lin, Jinyong; Lin, Juqiang; Liu, Nenrong; Huang, Zufang; Li, Buhong; Zeng, Haishan; Chen, Rong

    2015-05-01

    Gold nanoparticles are delivered into living cells by transient electroporation method to obtain intracellular surface-enhanced Raman spectroscopy (SERS). The subcellular localization of gold nanoparticles is characterized by transmission electron microscopy, and the forming large gold nanoaggregates are mostly found in the cytoplasm. The SERS detection of cells indicates that this kind of gold nanostructures induces a high signal enhancement of cellular chemical compositions, in addition to less cellular toxicity than that of silver nanoparticles. These results demonstrate that rapid incorporation of gold nanoparticles by electroporation into cells has great potential applications in the studies of cell biology and biomedicine.

  11. Plasma enhanced multistate storage capability of single ZnO nanowire based memory

    SciTech Connect

    Lai, Yunfeng Xin, Pucong; Cheng, Shuying; Yu, Jinling; Zheng, Qiao

    2015-01-19

    Multiple-state storage (MSS) is common for resistive random access memory, but the effects of plasma treatment on the MSS and the switching properties have been scarcely investigated. We have demonstrated a stable four-state storage capability of single zinc oxide nanowire (ZnO NW) treated by argon plasma. The electrical switching is attributed to the electron trapping and detrapping from the oxygen vacancies (V{sub o}s). The MSS relates to the electrical-thermal induced distribution of the V{sub o}s which determines electron transport behavior to show different resistance states. Additionally, programming (set and reset) voltages decrease with plasma treatment due to the thickness modulation of the interface barrier.

  12. A single-step lithography system based on an enhanced robotic adhesive dispenser

    NASA Astrophysics Data System (ADS)

    Xing, Jiyao; Rong, Weibin; Sun, Ding; Wang, Lefeng; Sun, Lining

    2016-09-01

    In the paper, we present a single-step lithography system whereby the robotically controlled micro-extrusion of resist adhesive onto a substrate surface to directly create resist adhesive patterns of interest. This system is modified from a robotic adhesive dispenser by shrinking the aperture of the nozzle to a few micrometers aiming to realize patterns at microscale. From experimental investigation, it is found that working factors including writing speed, working time, and applied pressure can be adopted to conveniently regulate the feature size (the width of the line features and the diameter of the dot features). To test its functionality, the system was used to pattern line features on silicon dioxide (SiO2) and generate an array of square-like silicon microstructure by combining with wet etching. It provides a simple and flexible alternative tool to facilitate the development of microfabrication.

  13. Structure-based molecular simulations reveal the enhancement of biased Brownian motions in single-headed kinesin.

    PubMed

    Kanada, Ryo; Kuwata, Takeshi; Kenzaki, Hiroo; Takada, Shoji

    2013-01-01

    Kinesin is a family of molecular motors that move unidirectionally along microtubules (MT) using ATP hydrolysis free energy. In the family, the conventional two-headed kinesin was experimentally characterized to move unidirectionally through "walking" in a hand-over-hand fashion by coordinated motions of the two heads. Interestingly a single-headed kinesin, a truncated KIF1A, still can generate a biased Brownian movement along MT, as observed by in vitro single molecule experiments. Thus, KIF1A must use a different mechanism from the conventional kinesin to achieve the unidirectional motions. Based on the energy landscape view of proteins, for the first time, we conducted a set of molecular simulations of the truncated KIF1A movements over an ATP hydrolysis cycle and found a mechanism exhibiting and enhancing stochastic forward-biased movements in a similar way to those in experiments. First, simulating stand-alone KIF1A, we did not find any biased movements, while we found that KIF1A with a large friction cargo-analog attached to the C-terminus can generate clearly biased Brownian movements upon an ATP hydrolysis cycle. The linked cargo-analog enhanced the detachment of the KIF1A from MT. Once detached, diffusion of the KIF1A head was restricted around the large cargo which was located in front of the head at the time of detachment, thus generating a forward bias of the diffusion. The cargo plays the role of a diffusional anchor, or cane, in KIF1A "walking."

  14. Pre-Trial EEG-Based Single-Trial Motor Performance Prediction to Enhance Neuroergonomics for a Hand Force Task.

    PubMed

    Meinel, Andreas; Castaño-Candamil, Sebastián; Reis, Janine; Tangermann, Michael

    2016-01-01

    We propose a framework for building electrophysiological predictors of single-trial motor performance variations, exemplified for SVIPT, a sequential isometric force control task suitable for hand motor rehabilitation after stroke. Electroencephalogram (EEG) data of 20 subjects with mean age of 53 years was recorded prior to and during 400 trials of SVIPT. They were executed within a single session with the non-dominant left hand, while receiving continuous visual feedback of the produced force trajectories. The behavioral data showed strong trial-by-trial performance variations for five clinically relevant metrics, which accounted for reaction time as well as for the smoothness and precision of the produced force trajectory. 18 out of 20 tested subjects remained after preprocessing and entered offline analysis. Source Power Comodulation (SPoC) was applied on EEG data of a short time interval prior to the start of each SVIPT trial. For 11 subjects, SPoC revealed robust oscillatory EEG subspace components, whose bandpower activity are predictive for the performance of the upcoming trial. Since SPoC may overfit to non-informative subspaces, we propose to apply three selection criteria accounting for the meaningfulness of the features. Across all subjects, the obtained components were spread along the frequency spectrum and showed a variety of spatial activity patterns. Those containing the highest level of predictive information resided in and close to the alpha band. Their spatial patterns resemble topologies reported for visual attention processes as well as those of imagined or executed hand motor tasks. In summary, we identified subject-specific single predictors that explain up to 36% of the performance fluctuations and may serve for enhancing neuroergonomics of motor rehabilitation scenarios. PMID:27199701

  15. Pre-Trial EEG-Based Single-Trial Motor Performance Prediction to Enhance Neuroergonomics for a Hand Force Task

    PubMed Central

    Meinel, Andreas; Castaño-Candamil, Sebastián; Reis, Janine; Tangermann, Michael

    2016-01-01

    We propose a framework for building electrophysiological predictors of single-trial motor performance variations, exemplified for SVIPT, a sequential isometric force control task suitable for hand motor rehabilitation after stroke. Electroencephalogram (EEG) data of 20 subjects with mean age of 53 years was recorded prior to and during 400 trials of SVIPT. They were executed within a single session with the non-dominant left hand, while receiving continuous visual feedback of the produced force trajectories. The behavioral data showed strong trial-by-trial performance variations for five clinically relevant metrics, which accounted for reaction time as well as for the smoothness and precision of the produced force trajectory. 18 out of 20 tested subjects remained after preprocessing and entered offline analysis. Source Power Comodulation (SPoC) was applied on EEG data of a short time interval prior to the start of each SVIPT trial. For 11 subjects, SPoC revealed robust oscillatory EEG subspace components, whose bandpower activity are predictive for the performance of the upcoming trial. Since SPoC may overfit to non-informative subspaces, we propose to apply three selection criteria accounting for the meaningfulness of the features. Across all subjects, the obtained components were spread along the frequency spectrum and showed a variety of spatial activity patterns. Those containing the highest level of predictive information resided in and close to the alpha band. Their spatial patterns resemble topologies reported for visual attention processes as well as those of imagined or executed hand motor tasks. In summary, we identified subject-specific single predictors that explain up to 36% of the performance fluctuations and may serve for enhancing neuroergonomics of motor rehabilitation scenarios. PMID:27199701

  16. Pre-Trial EEG-Based Single-Trial Motor Performance Prediction to Enhance Neuroergonomics for a Hand Force Task.

    PubMed

    Meinel, Andreas; Castaño-Candamil, Sebastián; Reis, Janine; Tangermann, Michael

    2016-01-01

    We propose a framework for building electrophysiological predictors of single-trial motor performance variations, exemplified for SVIPT, a sequential isometric force control task suitable for hand motor rehabilitation after stroke. Electroencephalogram (EEG) data of 20 subjects with mean age of 53 years was recorded prior to and during 400 trials of SVIPT. They were executed within a single session with the non-dominant left hand, while receiving continuous visual feedback of the produced force trajectories. The behavioral data showed strong trial-by-trial performance variations for five clinically relevant metrics, which accounted for reaction time as well as for the smoothness and precision of the produced force trajectory. 18 out of 20 tested subjects remained after preprocessing and entered offline analysis. Source Power Comodulation (SPoC) was applied on EEG data of a short time interval prior to the start of each SVIPT trial. For 11 subjects, SPoC revealed robust oscillatory EEG subspace components, whose bandpower activity are predictive for the performance of the upcoming trial. Since SPoC may overfit to non-informative subspaces, we propose to apply three selection criteria accounting for the meaningfulness of the features. Across all subjects, the obtained components were spread along the frequency spectrum and showed a variety of spatial activity patterns. Those containing the highest level of predictive information resided in and close to the alpha band. Their spatial patterns resemble topologies reported for visual attention processes as well as those of imagined or executed hand motor tasks. In summary, we identified subject-specific single predictors that explain up to 36% of the performance fluctuations and may serve for enhancing neuroergonomics of motor rehabilitation scenarios.

  17. Single-particle Raman measurements of gold nanoparticles used in surface-enhanced Raman scattering (SERS)-based sandwich immunoassays

    NASA Astrophysics Data System (ADS)

    Park, Hye-Young; Lipert, Robert J.; Porter, Marc D.

    2004-12-01

    The effect of particle size on the intensity of surface-enhanced Raman scattering (SERS) using labeled gold nanoparticles has been investigated. Two sets of experiments were preformed, both of which employed 632.8-nm laser excitation. The first entailed a sandwich immunoassay in which an antibody coupled to a smooth gold substrate selectively captured free-prostate specific antigen (f-PSA) from buffered aqueous solutions. The presence of captured f-PSA was then detected by the response of Raman-labeled immunogold nanoparticles with nominal diameters of 30, 40, 50, 60, or 80 nm. The resulting SERS responses were correlated to particle densities, which were determined by atomic force microscopy, by calculating the average response per particle after accounting for differences in particle surface area. This analysis showed that the magnitude of the SERS response increased with increasing particle size. The second set of experiments examined the response of individual nanoparticles. These experiments differed in that the labeled nanoparticles were coupled to the smooth gold substrate by an amine-terminated thiolate, yielding a much smaller average separation between the particles and substrate. The results revealed that particles with a diameter of ~70 nm exhibited the largest enhancement. The origin of the difference in the two sets of findings, which is attributed to the distance dependence of the plasmon coupling between the nanoparticles and underlying substrate, is briefly discussed.

  18. Microfluidic single-cell transcriptional analysis rationally identifies novel surface marker profiles to enhance cell-based therapies.

    PubMed

    Rennert, Robert C; Januszyk, Michael; Sorkin, Michael; Rodrigues, Melanie; Maan, Zeshaan N; Duscher, Dominik; Whittam, Alexander J; Kosaraju, Revanth; Chung, Michael T; Paik, Kevin; Li, Alexander Y; Findlay, Michael; Glotzbach, Jason P; Butte, Atul J; Gurtner, Geoffrey C

    2016-01-01

    Current progenitor cell therapies have only modest efficacy, which has limited their clinical adoption. This may be the result of a cellular heterogeneity that decreases the number of functional progenitors delivered to diseased tissue, and prevents correction of underlying pathologic cell population disruptions. Here, we develop a high-resolution method of identifying phenotypically distinct progenitor cell subpopulations via single-cell transcriptional analysis and advanced bioinformatics. When combined with high-throughput cell surface marker screening, this approach facilitates the rational selection of surface markers for prospective isolation of cell subpopulations with desired transcriptional profiles. We establish the usefulness of this platform in costly and highly morbid diabetic wounds by identifying a subpopulation of progenitor cells that is dysfunctional in the diabetic state, and normalizes diabetic wound healing rates following allogeneic application. We believe this work presents a logical framework for the development of targeted cell therapies that can be customized to any clinical application. PMID:27324848

  19. Microfluidic single-cell transcriptional analysis rationally identifies novel surface marker profiles to enhance cell-based therapies.

    PubMed

    Rennert, Robert C; Januszyk, Michael; Sorkin, Michael; Rodrigues, Melanie; Maan, Zeshaan N; Duscher, Dominik; Whittam, Alexander J; Kosaraju, Revanth; Chung, Michael T; Paik, Kevin; Li, Alexander Y; Findlay, Michael; Glotzbach, Jason P; Butte, Atul J; Gurtner, Geoffrey C

    2016-06-21

    Current progenitor cell therapies have only modest efficacy, which has limited their clinical adoption. This may be the result of a cellular heterogeneity that decreases the number of functional progenitors delivered to diseased tissue, and prevents correction of underlying pathologic cell population disruptions. Here, we develop a high-resolution method of identifying phenotypically distinct progenitor cell subpopulations via single-cell transcriptional analysis and advanced bioinformatics. When combined with high-throughput cell surface marker screening, this approach facilitates the rational selection of surface markers for prospective isolation of cell subpopulations with desired transcriptional profiles. We establish the usefulness of this platform in costly and highly morbid diabetic wounds by identifying a subpopulation of progenitor cells that is dysfunctional in the diabetic state, and normalizes diabetic wound healing rates following allogeneic application. We believe this work presents a logical framework for the development of targeted cell therapies that can be customized to any clinical application.

  20. A Single Methylene Group in Oligoalkylamine-Based Cationic Polymers and Lipids Promotes Enhanced mRNA Delivery.

    PubMed

    Jarzębińska, Anita; Pasewald, Tamara; Lambrecht, Jana; Mykhaylyk, Olga; Kümmerling, Linda; Beck, Philipp; Hasenpusch, Günther; Rudolph, Carsten; Plank, Christian; Dohmen, Christian

    2016-08-01

    The development of chemically modified mRNA holds great promise as a new class of biologic therapeutics. However, the intracellular delivery and endosomal escape of mRNA encapsulated in nanoparticles has not been systematically investigated. Here, we synthesized a diverse set of cationic polymers and lipids from a series of oligoalkylamines and subsequently characterized their mRNA delivery capability. Notably, a structure with an alternating alkyl chain length between amines showed the highest transfection efficiency, which was linked to a high buffering capacity in a narrow range of pH 6.2 to 6.5. Variation in only one methylene group resulted in enhanced mRNA delivery to both the murine liver as well as porcine lungs after systemic or aerosol administration, respectively. These findings reveal a novel fundamental structure-activity relationship for the delivery of mRNA that is independent of the class of mRNA carrier and define a promising new path of exploration in the field of mRNA therapeutics. PMID:27376704

  1. Part-per-trillion level SF6 detection using a quartz enhanced photoacoustic spectroscopy-based sensor with single-mode fiber-coupled quantum cascade laser excitation.

    PubMed

    Spagnolo, Vincenzo; Patimisco, Pietro; Borri, Simone; Scamarcio, Gaetano; Bernacki, Bruce E; Kriesel, Jason

    2012-11-01

    A sensitive spectroscopic sensor based on a hollow-core fiber-coupled quantum cascade laser (QCL) emitting at 10.54 μm and quartz enhanced photoacoustic spectroscopy (QEPAS) technique is reported. The design and realization of mid-IR fiber and coupler optics has ensured single-mode QCL beam delivery to the QEPAS sensor. The collimation optics was designed to produce a laser beam of significantly reduced beam size and waist so as to prevent illumination of the quartz tuning fork and microresonator tubes. SF(6) was selected as the target gas. A minimum detection sensitivity of 50 parts per trillion in 1 s was achieved with a QCL power of 18 mW, corresponding to a normalized noise-equivalent absorption of 2.7×10(-10) W·cm(-1)/Hz(1/2).

  2. Part-Per-Trillion Level SF6 Detection Using a Quartz Enhanced Photoacoustic Spectroscopy-Based Sensor with Single-Mode Fiber-Coupled Quantum Cascade Laser Excitation

    SciTech Connect

    Spagnolo, V.; Patimisco, P.; Borri, Simone; Scamarcio, G.; Bernacki, Bruce E.; Kriesel, J.M.

    2012-10-23

    A sensitive spectroscopic sensor based on a hollow-core fiber-coupled quantum cascade laser (QCL) emitting at 10.54 µm and quartz enhanced photoacoustic spectroscopy (QEPAS) technique is reported. The design and realization of mid-infrared fiber and coupler optics has ensured single-mode QCL beam delivery to the QEPAS sensor . The collimation optics was designed to produce a laser beam of significantly reduced beam size and waist so as to prevent illumination of the quartz tuning fork and micro-resonator tubes. SF6 was selected as the target gas. A minimum detection sensitivity of 50 parts per trillion in 1 s was achieved with a QCL power of 18 mW, corresponding to a normalized noise-equivalent absorption of 2.7x10-10 W•cm-1/Hz1/2.

  3. Enhanced genetic algorithm optimization model for a single reservoir operation based on hydropower generation: case study of Mosul reservoir, northern Iraq.

    PubMed

    Al-Aqeeli, Yousif H; Lee, T S; Abd Aziz, S

    2016-01-01

    Achievement of the optimal hydropower generation from operation of water reservoirs, is a complex problems. The purpose of this study was to formulate and improve an approach of a genetic algorithm optimization model (GAOM) in order to increase the maximization of annual hydropower generation for a single reservoir. For this purpose, two simulation algorithms were drafted and applied independently in that GAOM during 20 scenarios (years) for operation of Mosul reservoir, northern Iraq. The first algorithm was based on the traditional simulation of reservoir operation, whilst the second algorithm (Salg) enhanced the GAOM by changing the population values of GA through a new simulation process of reservoir operation. The performances of these two algorithms were evaluated through the comparison of their optimal values of annual hydropower generation during the 20 scenarios of operating. The GAOM achieved an increase in hydropower generation in 17 scenarios using these two algorithms, with the Salg being superior in all scenarios. All of these were done prior adding the evaporation (Ev) and precipitation (Pr) to the water balance equation. Next, the GAOM using the Salg was applied by taking into consideration the volumes of these two parameters. In this case, the optimal values obtained from the GAOM were compared, firstly with their counterpart that found using the same algorithm without taking into consideration of Ev and Pr, secondly with the observed values. The first comparison showed that the optimal values obtained in this case decreased in all scenarios, whilst maintaining the good results compared with the observed in the second comparison. The results proved the effectiveness of the Salg in increasing the hydropower generation through the enhanced approach of the GAOM. In addition, the results indicated to the importance of taking into account the Ev and Pr in the modelling of reservoirs operation.

  4. Enhanced genetic algorithm optimization model for a single reservoir operation based on hydropower generation: case study of Mosul reservoir, northern Iraq.

    PubMed

    Al-Aqeeli, Yousif H; Lee, T S; Abd Aziz, S

    2016-01-01

    Achievement of the optimal hydropower generation from operation of water reservoirs, is a complex problems. The purpose of this study was to formulate and improve an approach of a genetic algorithm optimization model (GAOM) in order to increase the maximization of annual hydropower generation for a single reservoir. For this purpose, two simulation algorithms were drafted and applied independently in that GAOM during 20 scenarios (years) for operation of Mosul reservoir, northern Iraq. The first algorithm was based on the traditional simulation of reservoir operation, whilst the second algorithm (Salg) enhanced the GAOM by changing the population values of GA through a new simulation process of reservoir operation. The performances of these two algorithms were evaluated through the comparison of their optimal values of annual hydropower generation during the 20 scenarios of operating. The GAOM achieved an increase in hydropower generation in 17 scenarios using these two algorithms, with the Salg being superior in all scenarios. All of these were done prior adding the evaporation (Ev) and precipitation (Pr) to the water balance equation. Next, the GAOM using the Salg was applied by taking into consideration the volumes of these two parameters. In this case, the optimal values obtained from the GAOM were compared, firstly with their counterpart that found using the same algorithm without taking into consideration of Ev and Pr, secondly with the observed values. The first comparison showed that the optimal values obtained in this case decreased in all scenarios, whilst maintaining the good results compared with the observed in the second comparison. The results proved the effectiveness of the Salg in increasing the hydropower generation through the enhanced approach of the GAOM. In addition, the results indicated to the importance of taking into account the Ev and Pr in the modelling of reservoirs operation. PMID:27390638

  5. Enhanced sensitivity of self-assembled-monolayer-based SPR immunosensor for detection of benzaldehyde using a single-step multi-sandwich immunoassay.

    PubMed

    Gobi, K Vengatajalabathy; Matsumoto, Kiyoshi; Toko, Kiyoshi; Ikezaki, Hidekazu; Miura, Norio

    2007-04-01

    This paper describes the fabrication and sensing characteristics of a self-assembled monolayer (SAM)-based surface plasmon resonance (SPR) immunosensor for detection of benzaldehyde (BZ). The functional sensing surface was fabricated by the immobilization of a benzaldehyde-ovalbumin conjugate (BZ-OVA) on Au-thiolate SAMs containing carboxyl end groups. Covalent binding of BZ-OVA on SAM was found to be dependent on the composition of the base SAM, and it is improved very much with the use of a mixed monolayer strategy. Based on SPR angle measurements, the functional sensor surface is established as a compact monolayer of BZ-OVA bound on the mixed SAM. The BZ-OVA-bound sensor surface undergoes immunoaffinity binding with anti-benzaldehyde antibody (BZ-Ab) selectively. An indirect inhibition immunoassay principle has been applied, in which analyte benzaldehyde solution was incubated with an optimal concentration of BZ-Ab for 5 min and injected over the sensor chip. Analyte benzaldehyde undergoes immunoreaction with BZ-Ab and makes it inactive for binding to BZ-OVA on the sensor chip. As a result, the SPR angle response decreases with an increase in the concentration of benzaldehyde. The fabricated immunosensor demonstrates a low detection limit (LDL) of 50 ppt (pg mL(-1)) with a response time of 5 min. Antibodies bound to the sensor chip during an immunoassay could be detached by a brief exposure to acidic pepsin. With this surface regeneration, reusability of the same sensor chip for as many as 30 determination cycles has been established. Sensitivity has been enhanced further with the application of an additional single-step multi-sandwich immunoassay step, in which the BZ-Ab bound to the sensor chip was treated with a mixture of biotin-labeled secondary antibody, streptavidin and biotin-bovine serum albumin (Bio-BSA) conjugate. With this approach, the SPR sensor signal increased by ca. 12 times and the low detection limit improved to 5 ppt with a total response

  6. Enhancement of Single-Photon Sources with Metamaterials

    NASA Astrophysics Data System (ADS)

    Shalaginov, M. Y.; Bogdanov, S.; Vorobyov, V. V.; Lagutchev, A. S.; Kildishev, A. V.; Akimov, A. V.; Boltasseva, A.; Shalaev, V. M.

    2015-06-01

    Scientists are looking for new, breakthrough solutions that can greatly advance computing and networking systems. These solutions will involve quantum properties of matter and light as promised by the ongoing experimental and theoretical work in the areas of quantum computation and communication. Quantum photonics is destined to play a central role in the development of such technologies due to the high transmission capacity and outstanding low-noise properties of photonic information channels. Among the vital problems to be solved in this direction, are efficient generation and collection of single photons. One approach to tackle these problems is based on engineering emission properties of available single-photon sources using metamaterials. Metamaterials are artificially engineered structures with sub-wavelength features whose optical properties go beyond the limitations of conventional materials. As promising single-photon sources, we have chosen nitrogen-vacancy (NV) color centers in diamond, which are capable to operate stably in a single-photon regime at room temperature in a solid state environment. In this chapter, we report both theoretical and experimental studies of the radiation from a nanodiamond single NV center placed near a hyperbolic metamaterial (HMM). In particular, we derive the reduction of excited-state lifetime and the enhancement of collected single-photon emission rate and compare them with the experimental observations. These results could be of great impact for future integrated quantum sources, especially owing to a CMOS-compatible approach to HMM synthesis.

  7. Spatial Attention Enhances Perceptual Processing of Single-Element Displays

    NASA Technical Reports Server (NTRS)

    Bacon, William; Johnston, James C.; Remington, Roger W.; Null, Cynthia H. (Technical Monitor)

    1994-01-01

    Shiu and Pashler (1993) reported that precueing masked, single-element displays had negligible effects on identification accuracy. They argued that spatial attention does not actually enhance stimulus perceptibility, but only reduces decision noise. Alternatively, such negative results may arise if cues are sub-optimal, or if masks place an insufficient premium on timely deployment of attention. We report results showing that valid cueing enhances processing of even single-element displays. Spatial attention does indeed enhance perceptual processes.

  8. Plasmon-enhanced emission from single fluorescent proteins

    NASA Astrophysics Data System (ADS)

    Donehue, Jessica E.; Haas, Beth L.; Wertz, Esther; Talicska, Courtney N.; Biteen, Julie S.

    2013-02-01

    In this work, we use evaporated gold nanoparticle films (GNPFs) as substrates for plasmon-enhanced imaging of two fluorescent proteins (FPs): mCherry and YFP. Through single-molecule epifluorescence microscopy, we show enhancement of single FP emission in the presence of GNPFs. The gold-coupled FPs demonstrate emission up to four times brighter and seven times longer lived, yielding order-of-magnitude enhancements in total photons detected. Ultimately, this results in increased localization accuracies for single-molecule imaging. Furthermore, we introduce preliminary results for enhancement of mCherry-labeled TcpP membrane proteins inside live Vibrio cholerae cells coupled to GNPFs. Our work indicates that plasmonic substrates are uniquely advantageous for super-resolution imaging and that plasmon-enhanced imaging is a promising technique for improving live cell single-molecule microscopy.

  9. Single-molecule surface- and tip-enhanced raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Pettinger, Bruno

    2010-08-01

    A review is given on single-molecule surface- and tip-enhanced Raman spectroscopy (SERS and TERS). It sketches the historical development along different routes toward huge near-field enhancements, the basis of single-molecule enhanced Raman spectroscopy; from SNOM to apertureless SNOM to tip-enhanced Raman spectroscopy (TERS) and microscopy; from SERS to single-molecule SERS to single-molecule TERS. The claim of extremely high enhancement factors of 1014 in single-molecule SERS is critically discussed, in particular in the view of recent experimental and theoretical results that limits the electromagnetic enhancement to ⩽ 1011. In the field of TERS only very few reports on single-molecule TERS exist: single-molecule TERS on dyes and on a protein (cytochrome c). In the latter case, TERS 'sees' even subunits of this protein, either amino-acids or the heme, depending on the orientation of the protein relative to the tip. The former case concerns the dye brilliant cresyl blue adsorbed either on a Au surface under ambient conditions or on a Au(111) surface in ultra high vacuum. These results indicate that significant progress is to be expected for TERS in general and for single-molecule TERS in particular.

  10. Laboratory evolution of Geobacter sulfurreducens for enhanced growth on lactate via a single-base-pair substitution in a transcriptional regulator

    PubMed Central

    Summers, Zarath M; Ueki, Toshiyuki; Ismail, Wael; Haveman, Shelley A; Lovley, Derek R

    2012-01-01

    The addition of organic compounds to groundwater in order to promote bioremediation may represent a new selective pressure on subsurface microorganisms. The ability of Geobacter sulfurreducens, which serves as a model for the Geobacter species that are important in various types of anaerobic groundwater bioremediation, to adapt for rapid metabolism of lactate, a common bioremediation amendment, was evaluated. Serial transfer of five parallel cultures in a medium with lactate as the sole electron donor yielded five strains that could metabolize lactate faster than the wild-type strain. Genome sequencing revealed that all five strains had non-synonymous single-nucleotide polymorphisms in the same gene, GSU0514, a putative transcriptional regulator. Introducing the single-base-pair mutation from one of the five strains into the wild-type strain conferred rapid growth on lactate. This strain and the five adaptively evolved strains had four to eight-fold higher transcript abundance than wild-type cells for genes for the two subunits of succinyl-CoA synthase, an enzyme required for growth on lactate. DNA-binding assays demonstrated that the protein encoded by GSU0514 bound to the putative promoter of the succinyl-CoA synthase operon. The binding sequence was not apparent elsewhere in the genome. These results demonstrate that a single-base-pair mutation in a transcriptional regulator can have a significant impact on the capacity for substrate utilization and suggest that adaptive evolution should be considered as a potential response of microorganisms to environmental change(s) imposed during bioremediation. PMID:22113376

  11. Highly enhanced gas sensing in single-walled carbon nanotube-based thin-film transistor sensors by ultraviolet light irradiation

    NASA Astrophysics Data System (ADS)

    Chen, Tingting; Wei, Liangming; Zhou, Zhihua; Shi, Diwen; Wang, Jian; Zhao, Jiang; Yu, Yuan; Wang, Ying; Zhang, Yafei

    2012-11-01

    Single-walled carbon nanotube (SWCNT) random networks are easily fabricated on a wafer scale, which provides an attractive path to large-scale SWCNT-based thin-film transistor (TFT) manufacturing. However, the mixture of semiconducting SWCNTs and metallic SWCNTs (m-SWCNTs) in the networks significantly limits the TFT performance due to the m-SWCNTs dominating the charge transport. In this paper, we have achieved a uniform and high-density SWCNT network throughout a complete 3-in. Si/SiO2 wafer using a solution-based assembly method. We further utilized UV radiation to etch m-SWCNTs from the networks, and a remarkable increase in the channel current on/off ratio ( I on/ I off) from 11 to 5.6 × 103 was observed. Furthermore, we used the SWCNT-TFTs as gas sensors to detect methyl methylphosphonate, a stimulant of benchmark threats. It was found that the SWCNT-TFT sensors treated with UV radiation show a much higher sensitivity and faster response to the analytes than those without treatment with UV radiation.

  12. Development of an enhanced bovine viral diarrhea virus subunit vaccine based on E2 glycoprotein fused to a single chain antibody which targets to antigen-presenting cells.

    PubMed

    Pecora, Andrea; Malacari, Darío A; Pérez Aguirreburualde, María S; Bellido, Demian; Escribano, José M; Dus Santos, María J; Wigdorovitz, Andrés

    2015-01-01

    Bovine viral diarrhea virus (BVDV) is an important cause of economic losses worldwide. E2 is an immunodominant protein and a promising candidate to develop subunit vaccines. To improve its immunogenicity, a truncated E2 (tE2) was fused to a single chain antibody named APCH, which targets to antigen-presenting cells. APCH-tE2 and tE2 proteins were expressed in the baculovirus system and their immunogenicity was firstly compared in guinea pigs. APCH-tE2 vaccine was the best one to evoke a humoral response, and for this reason, it was selected for a cattle vaccination experiment. All the bovines immunized with 1.5 μg of APCH-tE2 developed high levels of neutralizing antibodies against BVDV up to a year post-immunization, demonstrating its significant potential as a subunit vaccine. This novel vaccine is undergoing scale-up and was transferred to the private sector. Nowadays, it is being evaluated for registration as the first Argentinean subunit vaccine for cattle. PMID:25697468

  13. Development of an enhanced bovine viral diarrhea virus subunit vaccine based on E2 glycoprotein fused to a single chain antibody which targets to antigen-presenting cells.

    PubMed

    Pecora, Andrea; Malacari, Darío A; Pérez Aguirreburualde, María S; Bellido, Demian; Escribano, José M; Dus Santos, María J; Wigdorovitz, Andrés

    2015-01-01

    Bovine viral diarrhea virus (BVDV) is an important cause of economic losses worldwide. E2 is an immunodominant protein and a promising candidate to develop subunit vaccines. To improve its immunogenicity, a truncated E2 (tE2) was fused to a single chain antibody named APCH, which targets to antigen-presenting cells. APCH-tE2 and tE2 proteins were expressed in the baculovirus system and their immunogenicity was firstly compared in guinea pigs. APCH-tE2 vaccine was the best one to evoke a humoral response, and for this reason, it was selected for a cattle vaccination experiment. All the bovines immunized with 1.5 μg of APCH-tE2 developed high levels of neutralizing antibodies against BVDV up to a year post-immunization, demonstrating its significant potential as a subunit vaccine. This novel vaccine is undergoing scale-up and was transferred to the private sector. Nowadays, it is being evaluated for registration as the first Argentinean subunit vaccine for cattle.

  14. Nanoantenna enhancement for telecom-wavelength superconducting single photon detectors.

    PubMed

    Heath, Robert M; Tanner, Michael G; Drysdale, Timothy D; Miki, Shigehito; Giannini, Vincenzo; Maier, Stefan A; Hadfield, Robert H

    2015-02-11

    Superconducting nanowire single photon detectors are rapidly emerging as a key infrared photon-counting technology. Two front-side-coupled silver dipole nanoantennas, simulated to have resonances at 1480 and 1525 nm, were fabricated in a two-step process. An enhancement of 50 to 130% in the system detection efficiency was observed when illuminating the antennas. This offers a pathway to increasing absorption into superconducting nanowires, creating larger active areas, and achieving more efficient detection at longer wavelengths.

  15. Enhanced flow in smooth single-file channel.

    PubMed

    Roy Majumder, Shashwati; Choudhury, Niharendu; Ghosh, Swapan K

    2007-08-01

    We investigate the flux of particles in a smooth single-file channel where particles cannot cross each other as well as in wider channels of varying cross section where particles execute normal diffusion. All the channels are connected to an infinite reservoir at one end and the flux of particles is measured at the other open end. We perform random walk Monte Carlo simulation using lattice model. The flux decreases monotonically as the channel cross section is increased from single-file channel to wider channel and finally reaches a constant value for a sufficiently wide channel. The observation of enhanced flux in single-file channel as compared to a wider channel can be tested for efficient separation of particles through smooth nanochannels.

  16. Single-ZnO-Nanobelt-Based Single-Electron Transistors

    NASA Astrophysics Data System (ADS)

    Ji, Xiao-Fan; Xu, Zheng; Cao, Shuo; Qiu, Kang-Sheng; Tang, Jing; Zhang, Xi-Tian; Xu, Xiu-Lai

    2014-06-01

    We fabricate single electron transistors based on a single ZnO nanobelt using standard micro-fabrication techniques. The transport properties of the devices are characterized at room temperature and at low temperature (4.2 K). At room temperature, the source-drain current increases linearly as the bias voltage increases, indicating a good ohmic contact in the transistors. At 4.2 K, a Coulomb blockade regime is observed up to a bias voltage of a few millivolts. With scanning the back gate voltage, Coulomb oscillations can be clearly resolved with a period around 1 V. From the oscillations, the charging energy for the single electron transistor is calculated to be about 10 meV, which suggests that confined quantum dots exist with sizes around 35 nm in diameter. The irregular Coulomb diamonds are observed due to the multi-tunneling junctions between dots in the nanobelt.

  17. Image enhancement based on edge boosting algorithm

    NASA Astrophysics Data System (ADS)

    Ngernplubpla, Jaturon; Chitsobhuk, Orachat

    2015-12-01

    In this paper, a technique for image enhancement based on proposed edge boosting algorithm to reconstruct high quality image from a single low resolution image is described. The difficulty in single-image super-resolution is that the generic image priors resided in the low resolution input image may not be sufficient to generate the effective solutions. In order to achieve a success in super-resolution reconstruction, efficient prior knowledge should be estimated. The statistics of gradient priors in terms of priority map based on separable gradient estimation, maximum likelihood edge estimation, and local variance are introduced. The proposed edge boosting algorithm takes advantages of these gradient statistics to select the appropriate enhancement weights. The larger weights are applied to the higher frequency details while the low frequency details are smoothed. From the experimental results, the significant performance improvement quantitatively and perceptually is illustrated. It can be seen that the proposed edge boosting algorithm demonstrates high quality results with fewer artifacts, sharper edges, superior texture areas, and finer detail with low noise.

  18. Enhancing Single Molecule Imaging in Optofluidics and Microfluidics

    PubMed Central

    Vasdekis, Andreas E.; Laporte, Gregoire P.J.

    2011-01-01

    Microfluidics and optofluidics have revolutionized high-throughput analysis and chemical synthesis over the past decade. Single molecule imaging has witnessed similar growth, due to its capacity to reveal heterogeneities at high spatial and temporal resolutions. However, both resolution types are dependent on the signal to noise ratio (SNR) of the image. In this paper, we review how the SNR can be enhanced in optofluidics and microfluidics. Starting with optofluidics, we outline integrated photonic structures that increase the signal emitted by single chromophores and minimize the excitation volume. Turning then to microfluidics, we review the compatible functionalization strategies that reduce noise stemming from non-specific interactions and architectures that minimize bleaching and blinking. PMID:21954349

  19. Enhancing single molecule imaging in optofluidics and microfluidics.

    PubMed

    Vasdekis, Andreas E; Laporte, Gregoire P J

    2011-01-01

    Microfluidics and optofluidics have revolutionized high-throughput analysis and chemical synthesis over the past decade. Single molecule imaging has witnessed similar growth, due to its capacity to reveal heterogeneities at high spatial and temporal resolutions. However, both resolution types are dependent on the signal to noise ratio (SNR) of the image. In this paper, we review how the SNR can be enhanced in optofluidics and microfluidics. Starting with optofluidics, we outline integrated photonic structures that increase the signal emitted by single chromophores and minimize the excitation volume. Turning then to microfluidics, we review the compatible functionalization strategies that reduce noise stemming from non-specific interactions and architectures that minimize bleaching and blinking.

  20. Enhanced Sensitivity in a Superluminal Single Mode DPAL Cavity at Room Temperature

    NASA Astrophysics Data System (ADS)

    Abi-Salloum, Tony; Yablon, Joshua; Tseng, Shih; Shahriar, Selim

    2012-06-01

    The note beat between two counter-propagating beams in a cavity is used to measure the effective change of the length of the cavity or interferometer for applications such as optical gyroscopes, vibrometers, and gravitational wave detectors. We show in this talk how a superluminal single mode laser cavity can enhance the measured note beat dramatically. We consider the inhomogeneous broadening case and study the dependence of the enhancement factor on few key parameters. We also show how Diode Pump Alkali Lasers (DPAL) are excellent candidates for such devices. Using a Rubidium based DPAL, we study the characteristics of these lasers and their effect on the proposed enhanced sensitivity.

  1. Environment-adaptive speech enhancement for bilateral cochlear implants using a single processor.

    PubMed

    Mirzahasanloo, Taher S; Kehtarnavaz, Nasser; Gopalakrishna, Vanishree; Loizou, Philipos C

    2013-05-01

    A computationally efficient speech enhancement pipeline in noisy environments based on a single-processor implementation is developed for utilization in bilateral cochlear implant systems. A two-channel joint objective function is defined and a closed form solution is obtained based on the weighted-Euclidean distortion measure. The computational efficiency and no need for synchronization aspects of this pipeline make it a suitable solution for real-time deployment. A speech quality measure is used to show its effectiveness in six different noisy environments as compared to a similar one-channel enhancement pipeline when using two separate processors or when using independent sequential processing.

  2. Environment-adaptive speech enhancement for bilateral cochlear implants using a single processor☆

    PubMed Central

    Mirzahasanloo, Taher S.; Kehtarnavaz, Nasser; Gopalakrishna, Vanishree; Loizou, Philipos C.

    2013-01-01

    A computationally efficient speech enhancement pipeline in noisy environments based on a single-processor implementation is developed for utilization in bilateral cochlear implant systems. A two-channel joint objective function is defined and a closed form solution is obtained based on the weighted-Euclidean distortion measure. The computational efficiency and no need for synchronization aspects of this pipeline make it a suitable solution for real-time deployment. A speech quality measure is used to show its effectiveness in six different noisy environments as compared to a similar one-channel enhancement pipeline when using two separate processors or when using independent sequential processing. PMID:24610967

  3. Single molecule surface enhanced resonance Raman scattering (SERRS) of the enhanced green fluorescent protein (EGFP)

    NASA Astrophysics Data System (ADS)

    Hofkens, Johan; De Schryver, Frans C.; Cotlet, Mircea; Habuchi, Satoshi

    2004-06-01

    One of the most intriguing findings in single molecule spectroscopy (SMS) is the observation of Raman spectra of individual molecules, despite the small cross section of the transitions involved. The observation of the spectra can be explained by the surface enhanced Raman scattering (SERRS) effect. At the single-molecule level, the SERRS-spectra recorded as a function of time reveal inhomogeneous behaviour such as on/off blinking, spectral diffusion, intensity fluctuations of vibrational line, and even splitting of some lines within the spectrum of one molecule. Single-molecule SERRS (SM-SERRS) spectroscopy opens up exciting opportunities in the field of biophysics and biomedical spectroscopy. The first example of single protein SERRS was performed on hemoglobin. However, the possibility of extracting the heme group by silver sols can not be excluded. Here we report on SM-SERRS spectra of enhanced green fluorescent protein (EGFP) in which the chromophore is kept in the protein. The time series of SM-SERRS spectra suggest the conversion of the EGFP chromophore between the deprotonated and the protonated form. Autocorrelation analysis of SM-SERRS trajectory reveals the presence of fast dynamics taking place in the protein. Our findings show the potential of the technique to study structural dynamics of protein molecules.

  4. Single well tracer method to evaluate enhanced recovery

    DOEpatents

    Sheely, Jr., Clyde Q.; Baldwin, Jr., David E.

    1978-01-01

    Data useful to evaluate the effectiveness of or to design an enhanced recovery process (the recovery process involving mobilizing and moving hydrocarbons through a hydrocarbon-bearing subterranean formation from an injection well to a production well by injecting a mobilizing fluid into the injection well) are obtained by a process which comprises sequentially: determining hydrocarbon saturation in the formation in a volume in the formation near a well bore penetrating the formation, injecting sufficient of the mobilizing fluid to mobilize and move hydrocarbons from a volume in the formation near the well bore penetrating the formation, and determining by the single well tracer method a hydrocarbon saturation profile in a volume from which hydrocarbons are moved. The single well tracer method employed is disclosed by U.S. Pat. No. 3,623,842. The process is useful to evaluate surfactant floods, water floods, polymer floods, CO.sub.2 floods, caustic floods, micellar floods, and the like in the reservoir in much less time at greatly reduced costs, compared to conventional multi-well pilot test.

  5. Overtone resonance enhanced single-tube on-beam quartz enhanced photoacoustic spectrophone

    NASA Astrophysics Data System (ADS)

    Zheng, Huadan; Dong, Lei; Sampaolo, Angelo; Patimisco, Pietro; Ma, Weiguang; Zhang, Lei; Yin, Wangbao; Xiao, Liantuan; Spagnolo, Vincenzo; Jia, Suotang; Tittel, Frank K.

    2016-09-01

    A single-tube on-beam quartz enhanced photoacoustic spectroscopy (SO-QEPAS) spectrophone, which employs a custom-made quartz tuning fork (QTF) having a prong spacing of 700 μm and operating at the 1st overtone flexural mode, is reported. The design of QTF prong geometry allows the bare QTF to possess twice higher Q-factor values for the 1st overtone resonance mode falling at ˜17.7 kHz than in the fundamental resonance mode at ˜2.8 kHz, resulting in an 8 times higher QEPAS signal amplitude when operating in the 1st overtone resonance mode. Both the vertical position and length of the single-tube acoustic micro-resonator (AmR) were optimized to attain optimal spectrophone performance. Benefiting from the high overtone resonance frequency and the quasi 1st harmonic acoustic standing waves generated in the SO-QEPAS configuration, the AmR length is reduced to 14.5 mm. This allows the realization of compact spectrophone and facilitates the laser beam alignment through the QTF + AmR system. The signal enhancement in the overtone resonance mode and the high acoustic coupling efficiency between the AmR and QTF in the SO-QEPAS configuration yields an overall sensitivity enhancement factor of ˜380 with respect to the bare custom QTF operating in the fundamental resonance mode.

  6. Nanoscale mapping of intrinsic defects in single-layer graphene using tip-enhanced Raman spectroscopy.

    PubMed

    Su, Weitao; Kumar, Naresh; Dai, Ning; Roy, Debdulal

    2016-07-01

    Non-gap mode tip-enhanced Raman spectroscopy (TERS) is used for the first time to successfully map the intrinsic defects in single-layer graphene with 20 nm spatial resolution. The nanoscale Raman mapping is enabled by an unprecedented near-field to far-field signal contrast of 8.5 at the Ag-coated TERS tip-apex. These results demonstrate the potential of TERS for characterisation of defects in single-layer graphene-based devices at the nanometre length-scale. PMID:27279142

  7. Enhanced Spin Hall Effect by Single Antidot Potential

    NASA Astrophysics Data System (ADS)

    Eto, Mikio; Yokoyama, Tomohiro

    2009-03-01

    We theoretically investigate an extrinsic spin Hall effect in semiconductor heterostructures due to the scattering by an artificial potential created by a single antidot, STM tip, etc. The strength of the potential is electrically tunable. First, we formulate the spin Hall effect in terms of phase shifts in the partial wave expansion for two-dimensional electron gas. For scattered electrons in θ direction, we obtain a spin polarization P(θ) perpendicular to the two-dimensional plane [P(-θ)=-P (θ)]. The spin polarization P(θ) is significantly enhanced by an attractive potential when the resonant condition of a partial wave is satisfied by tuning the potential strength. Second, we study the spin Hall effect in a three-terminal device with an antidot at the junction. The conductance and spin polarization are evaluated numerically.ootnotetextM. Yamamoto and B. Kramer, J. Appl. Phys. 103, 123703 (2008), for repulsive potential. We obtain a spin polarization of more than 50% due to the resonant scattering when the attractive potential is properly tuned.

  8. Surface enhanced Raman scattering detection of single R6G molecules on nanoporous gold films

    NASA Astrophysics Data System (ADS)

    Liu, Hongwen; Zhang, L.; Yamaguchi, Y.; Iwasaki, H.; Inouye, Y.; Xue, Q. K.; Chen, M. W.

    2011-03-01

    Detecting single molecules with high sensitivity and molecular specificity is of great practical interest in many fields such as chemistry, biology, medicine, and pharmacology. For this purpose, cheap and highly active substrates are of crucial importance. Recently, nanoporous metals (NPMs), with a three-dimensional continuous network structure and pore channels usually much smaller than the wavelength of visible light, revealed outstanding optical properties in surface enhanced Raman scattering (SERS). In this work, we further modify the nanoporous gold films by growing a high density of gold nano-tips on the surface. Extremely focused electromagnetic fields can be produced at the apex of the nano-tips, resulting in so-called hot spots. With this NPM-based and affordable substrate, single molecule-detection is achievable with ultrahigh enhancement in SERS.

  9. DNA Origami Nanoantennas with over 5000-fold Fluorescence Enhancement and Single-Molecule Detection at 25 μM.

    PubMed

    Puchkova, Anastasiya; Vietz, Carolin; Pibiri, Enrico; Wünsch, Bettina; Sanz Paz, María; Acuna, Guillermo P; Tinnefeld, Philip

    2015-12-01

    Optical nanoantennas are known to focus freely propagating light and reversely to mediate the emission of a light source located at the nanoantenna hotspot. These effects were previously exploited for fluorescence enhancement and single-molecule detection at elevated concentrations. We present a new generation of self-assembled DNA origami based optical nanoantennas with improved robustness, reduced interparticle distance, and optimized quantum-yield improvement to achieve more than 5000-fold fluorescence enhancement and single-molecule detection at 25 μM background fluorophore concentration. Besides outperforming lithographic optical antennas, DNA origami nanoantennas are additionally capable of incorporating single emitters or biomolecular assays at the antenna hotspot. PMID:26523768

  10. DNA Origami Nanoantennas with over 5000-fold Fluorescence Enhancement and Single-Molecule Detection at 25 μM.

    PubMed

    Puchkova, Anastasiya; Vietz, Carolin; Pibiri, Enrico; Wünsch, Bettina; Sanz Paz, María; Acuna, Guillermo P; Tinnefeld, Philip

    2015-12-01

    Optical nanoantennas are known to focus freely propagating light and reversely to mediate the emission of a light source located at the nanoantenna hotspot. These effects were previously exploited for fluorescence enhancement and single-molecule detection at elevated concentrations. We present a new generation of self-assembled DNA origami based optical nanoantennas with improved robustness, reduced interparticle distance, and optimized quantum-yield improvement to achieve more than 5000-fold fluorescence enhancement and single-molecule detection at 25 μM background fluorophore concentration. Besides outperforming lithographic optical antennas, DNA origami nanoantennas are additionally capable of incorporating single emitters or biomolecular assays at the antenna hotspot.

  11. Enhanced efficiency of single and tandem organic solar cells incorporating a diketopyrrolopyrrole-based low-bandgap polymer by utilizing combined ZnO/polyelectrolyte electron-transport layers.

    PubMed

    Jo, Jang; Pouliot, Jean-Rémi; Wynands, David; Collins, Samuel D; Kim, Jin Young; Nguyen, Thanh Luan; Woo, Han Young; Sun, Yanming; Leclerc, Mario; Heeger, Alan J

    2013-09-14

    Power conversion efficiency up to 8.6% is achieved for a solution-processed tandem solar cell based on a diketopyrrolopyrrole-containing polymer as the low-bandgap material after using a thin polyelectrolyte layer to modify the electron-transport ZnO layers, indicating that interfacial engineering is a useful approach to further enhancing the efficiency of tandem organic solar cells. PMID:23847037

  12. Nanoparticle Based Surface-Enhanced Raman Spectroscopy

    SciTech Connect

    Talley, C E; Huser, T R; Hollars, C W; Jusinski, L; Laurence, T; Lane, S M

    2005-01-03

    Surface-enhanced Raman scattering is a powerful tool for the investigation of biological samples. Following a brief introduction to Raman and surface-enhanced Raman scattering, several examples of biophotonic applications of SERS are discussed. The concept of nanoparticle based sensors using SERS is introduced and the development of these sensors is discussed.

  13. Silver-enhanced fluorescence emission of single quantum dot nanocomposites.

    PubMed

    Fu, Yi; Zhang, Jian; Lakowicz, Joseph R

    2009-01-21

    A novel plasmon-coupled quantum dot (QD) nanocomposite via covalently interfacing the QD surfaces with silver nanoparticles was developed with greatly reduced blinking and enhanced emission fluorescence.

  14. All-Dielectric Silicon Nanogap Antennas To Enhance the Fluorescence of Single Molecules.

    PubMed

    Regmi, Raju; Berthelot, Johann; Winkler, Pamina M; Mivelle, Mathieu; Proust, Julien; Bedu, Frédéric; Ozerov, Igor; Begou, Thomas; Lumeau, Julien; Rigneault, Hervé; García-Parajó, María F; Bidault, Sébastien; Wenger, Jérôme; Bonod, Nicolas

    2016-08-10

    Plasmonic antennas have a profound impact on nanophotonics as they provide efficient means to manipulate light and enhance light-matter interactions at the nanoscale. However, the large absorption losses found in metals can severely limit the plasmonic applications in the visible spectral range. Here, we demonstrate the effectiveness of an alternative approach using all-dielectric nanoantennas based on silicon dimers to enhance the fluorescence detection of single molecules. The silicon antenna design is optimized to confine the near-field intensity in the 20 nm nanogap and reach a 270-fold fluorescence enhancement in a nanoscale volume of λ(3)/1800 with dielectric materials only. Our conclusions are assessed by combining polarization resolved optical spectroscopy of individual antennas, scanning electron microscopy, numerical simulations, fluorescence lifetime measurements, fluorescence burst analysis, and fluorescence correlation spectroscopy. This work demonstrates that all-silicon nanoantennas are a valid alternative to plasmonic devices for enhanced single molecule fluorescence sensing, with the additional key advantages of reduced nonradiative quenching, negligible heat generation, cost-efficiency, and complementary metal-oxide-semiconductor (CMOS) compatibility. PMID:27399057

  15. All-Dielectric Silicon Nanogap Antennas To Enhance the Fluorescence of Single Molecules.

    PubMed

    Regmi, Raju; Berthelot, Johann; Winkler, Pamina M; Mivelle, Mathieu; Proust, Julien; Bedu, Frédéric; Ozerov, Igor; Begou, Thomas; Lumeau, Julien; Rigneault, Hervé; García-Parajó, María F; Bidault, Sébastien; Wenger, Jérôme; Bonod, Nicolas

    2016-08-10

    Plasmonic antennas have a profound impact on nanophotonics as they provide efficient means to manipulate light and enhance light-matter interactions at the nanoscale. However, the large absorption losses found in metals can severely limit the plasmonic applications in the visible spectral range. Here, we demonstrate the effectiveness of an alternative approach using all-dielectric nanoantennas based on silicon dimers to enhance the fluorescence detection of single molecules. The silicon antenna design is optimized to confine the near-field intensity in the 20 nm nanogap and reach a 270-fold fluorescence enhancement in a nanoscale volume of λ(3)/1800 with dielectric materials only. Our conclusions are assessed by combining polarization resolved optical spectroscopy of individual antennas, scanning electron microscopy, numerical simulations, fluorescence lifetime measurements, fluorescence burst analysis, and fluorescence correlation spectroscopy. This work demonstrates that all-silicon nanoantennas are a valid alternative to plasmonic devices for enhanced single molecule fluorescence sensing, with the additional key advantages of reduced nonradiative quenching, negligible heat generation, cost-efficiency, and complementary metal-oxide-semiconductor (CMOS) compatibility.

  16. Corona Enhancement and Mosaic Architecture for Prognosis and Selection Between of Liver Resection Versus Transcatheter Arterial Chemoembolization in Single Hepatocellular Carcinomas >5 cm Without Extrahepatic Metastases: An Imaging-Based Retrospective Study.

    PubMed

    Li, Meng; Xin, Yongjie; Fu, Sirui; Liu, Zaiyi; Li, Yong; Hu, Baoshan; Chen, Shuting; Liang, Changhong; Lu, Ligong

    2016-01-01

    Corona enhancement and mosaic architecture are 2 radiologic features of hepatocellular carcinoma (HCC). However, neither their prognostic values nor their impacts on the selection of liver resection (LR) versus transcatheter arterial chemoembolization (TACE) as treatment modalities have been established.We retrospectively analyzed 275 patients with a single HCC lesion >5 cm without extrahepatic metastasis treated with LR or TACE. In LR patients, the overall survival (OS) and time to progression (TTP) were compared between corona enhancement negative (corona-) versus positive (corona+) and mosaic architecture negative (mosaic-) versus positive (mosaic+) patients. Furthermore, by the combination of corona and mosaic, LR patients were divided into negative for both corona and mosaic patterns (LR-/-), positive for only 1 feature (LR+/-), and positive for both (LR+/+); their OS and TTP were compared to those of the TACE group. Cox regression was performed to identify independent factors for OS.In the survival plots for LR, corona- had better OS and TTP than corona+, and mosaic- had better OS than mosaic+. There was no significant difference in TTP between the subgroups. On Cox regression analysis, corona enhancement, but not mosaic architecture, was a significant factor for OS, whereas neither were a significant factor for TTP. In TACE patients, neither corona nor mosaic patterns had significant correlations with OS or TTP. In the whole population, LR-/ and LR+/- subgroups had similar OS, which was better than the LR+/+ and TACE groups. Moreover, LR-/- and LR+/- patients had better TTP than TACE patients, but there were no differences between the LR-/- versus LR+/-, LR-/ versus LR+/+, LR+/- versus LR+/+, and LR+/+ versus TACE groups. On Cox regression analysis, the presence of corona/mosaic patterns was an independent prognostic factor for OS.Our results showed that, for patients with a single HCC >5 cm without extrahepatic metastasis, corona and mosaic patterns are

  17. Corona Enhancement and Mosaic Architecture for Prognosis and Selection Between of Liver Resection Versus Transcatheter Arterial Chemoembolization in Single Hepatocellular Carcinomas >5 cm Without Extrahepatic Metastases: An Imaging-Based Retrospective Study.

    PubMed

    Li, Meng; Xin, Yongjie; Fu, Sirui; Liu, Zaiyi; Li, Yong; Hu, Baoshan; Chen, Shuting; Liang, Changhong; Lu, Ligong

    2016-01-01

    Corona enhancement and mosaic architecture are 2 radiologic features of hepatocellular carcinoma (HCC). However, neither their prognostic values nor their impacts on the selection of liver resection (LR) versus transcatheter arterial chemoembolization (TACE) as treatment modalities have been established.We retrospectively analyzed 275 patients with a single HCC lesion >5 cm without extrahepatic metastasis treated with LR or TACE. In LR patients, the overall survival (OS) and time to progression (TTP) were compared between corona enhancement negative (corona-) versus positive (corona+) and mosaic architecture negative (mosaic-) versus positive (mosaic+) patients. Furthermore, by the combination of corona and mosaic, LR patients were divided into negative for both corona and mosaic patterns (LR-/-), positive for only 1 feature (LR+/-), and positive for both (LR+/+); their OS and TTP were compared to those of the TACE group. Cox regression was performed to identify independent factors for OS.In the survival plots for LR, corona- had better OS and TTP than corona+, and mosaic- had better OS than mosaic+. There was no significant difference in TTP between the subgroups. On Cox regression analysis, corona enhancement, but not mosaic architecture, was a significant factor for OS, whereas neither were a significant factor for TTP. In TACE patients, neither corona nor mosaic patterns had significant correlations with OS or TTP. In the whole population, LR-/ and LR+/- subgroups had similar OS, which was better than the LR+/+ and TACE groups. Moreover, LR-/- and LR+/- patients had better TTP than TACE patients, but there were no differences between the LR-/- versus LR+/-, LR-/ versus LR+/+, LR+/- versus LR+/+, and LR+/+ versus TACE groups. On Cox regression analysis, the presence of corona/mosaic patterns was an independent prognostic factor for OS.Our results showed that, for patients with a single HCC >5 cm without extrahepatic metastasis, corona and mosaic patterns are

  18. Maxwell's demon based on a single qubit

    NASA Astrophysics Data System (ADS)

    Pekola, J. P.; Golubev, D. S.; Averin, D. V.

    2016-01-01

    We propose and analyze Maxwell's demon based on a single qubit with avoided level crossing. Its operation cycle consists of adiabatic drive to the point of minimum energy separation, measurement of the qubit state, and conditional feedback. We show that the heat extracted from the bath at temperature T can ideally approach the Landauer limit of kBT ln2 per cycle even in the quantum regime. Practical demon efficiency is limited by the interplay of Landau-Zener transitions and coupling to the bath. We suggest that an experimental demonstration of the demon is fully feasible using one of the standard superconducting qubits.

  19. Conductance and Surface-Enhanced Raman Scattering of Single Molecules Utilizing Dimers of Nanoparticles

    NASA Astrophysics Data System (ADS)

    Dadosh, Tali

    In the past few years, the field of molecular electronics and in particular, the development of new techniques for contacting and measuring single molecules, has emerged, providing new insights into this field. The relatively small size of a molecule, typically of the order of 1 nm, requires innovative approaches in order to develop functioning single-molecule devices. The experimental methods currently used for single-molecule measurements provide little control over the number of molecules bridging the gap or the local electronic properties of the metal-molecule contact. In this thesis, a new approach for contacting a single molecule is presented that provides better control of these parameters. Our method is based on synthesizing a dimer structure consisting of two gold colloids connected by a thiol group to either side of the molecule. This structure is then positioned between two electrodes by electrostatic trapping and, thus, the conductance of the molecule can be measured. The fundamental questions addressed by the field of molecular electronics are as follows: "what is the conductivity of a junction containing an individual molecule and how is it affected by the molecule's specific structure?" We were able to shed some light on these questions by studying the electrical conduction through three short organic molecules that differ by their degree of conjugation. We will consider here a fully conjugated molecule, 4,4'-biphenyldithiol (BPD), Bis-(4-mercaptophenyl)-ether (BPE), in which the conjugation is broken at the center by an oxygen atom, and 1,4-benzenedimethanethiol (BDMT), where the conjugation is broken near the contacts by a methylene group. We found that the presence of localizing groups such as the oxygen in the BPE and the methylene groups in the BDMT suppresses the electrical conduction dramatically, relative to the conjugated molecule, BPD. A unique feature of the BPD molecule is the appearance of reproducible, pronounced peaks in its

  20. Metal-enhanced fluorescence of single green fluorescent protein (GFP)

    SciTech Connect

    Fu Yi; Zhang Jian; Lakowicz, Joseph R.

    2008-11-28

    The green fluorescent protein (GFP) has emerged as a powerful reporter molecule for monitoring gene expression, protein localization, and protein-protein interaction. However, the detection of low concentrations of GFPs is limited by the weakness of the fluorescent signal and the low photostability. In this report, we observed the proximity of single GFPs to metallic silver nanoparticles increases its fluorescence intensity approximately 6-fold and decreases the decay time. Single protein molecules on the silvered surfaces emitted 10-fold more photons as compared to glass prior to photobleaching. The photostability of single GFP has increased to some extent. Accordingly, we observed longer duration time and suppressed blinking. The single-molecule lifetime histograms indicate the relatively heterogeneous distributions of protein mutants inside the structure.

  1. Enhanced identification of peptides lacking basic residues by LC-ESI-MS/MS analysis of singly charged peptides.

    PubMed

    Biniossek, Martin L; Schilling, Oliver

    2012-05-01

    Peptide sequences lacking basic residues (arginine, lysine, or histidine, referred to as "base-less") are of particular importance in proteomic experiments targeting protein C-termini or employing nontryptic proteases such as GluC or chymotrypsin. We demonstrate enhanced identification of base-less peptides by focused analysis of singly charged precursors in liquid chromatography (LC) electrospray ionization (ESI) tandem mass spectrometry (MS/MS). Singly charged precursors are often excluded from fragmentation and sequence analysis in LC-MS/MS. We generated different pools of base-less and base-containing peptides by tryptic and nontryptic digestion of bacterial proteomes. Focused LC-MS/MS analysis of singly charged precursor ions yielded predominantly base-less peptide identifications. Similar numbers of base-less peptides were identified by LC-MS/M Sanalysis targeting multiply charged precursors. There was little redundancy between the base-less sequences derived by both MS/MS schemes. In the present experimental outcome, additional LC-MS/MS analysis of singly charged precursors substantially increased the identification rate of base-less sequences derived from multiply charged precursors. In conclusion, LC-MS/MS based identification of base-less peptides is substantially enhanced by additional focused analysis of singly charged precursors.

  2. Tip-Enhanced Raman Spectroscopy and Microscopy on Single Dye Molecules with 15nm Resolution

    NASA Astrophysics Data System (ADS)

    Steidtner, Jens; Pettinger, Bruno

    2008-06-01

    Our recently developed approach of UHV-tip-enhanced Raman spectroscopy permits us to acquire Raman spectra of a few single brilliant cresyl blue (BCB) molecules and even a single one adsorbed on a Au(111) surface. This is substantiated by simultaneously recorded STM images. Furthermore, because of the reduced photobleaching in UHV, the time frame for spectral acquisition is sufficiently extended to allow tip-enhanced Raman imaging of a single BCB molecule with a lateral resolution of 15 nm.

  3. Selective uptake of single-walled carbon nanotubes by circulating monocytes for enhanced tumour delivery.

    PubMed

    Smith, Bryan Ronain; Ghosn, Eliver Eid Bou; Rallapalli, Harikrishna; Prescher, Jennifer A; Larson, Timothy; Herzenberg, Leonore A; Gambhir, Sanjiv Sam

    2014-06-01

    In cancer imaging, nanoparticle biodistribution is typically visualized in living subjects using 'bulk' imaging modalities such as magnetic resonance imaging, computerized tomography and whole-body fluorescence. Accordingly, nanoparticle influx is observed only macroscopically, and the mechanisms by which they target cancer remain elusive. Nanoparticles are assumed to accumulate via several targeting mechanisms, particularly extravasation (leakage into tumour). Here, we show that, in addition to conventional nanoparticle-uptake mechanisms, single-walled carbon nanotubes are almost exclusively taken up by a single immune cell subset, Ly-6C(hi) monocytes (almost 100% uptake in Ly-6C(hi) monocytes, below 3% in all other circulating cells), and delivered to the tumour in mice. We also demonstrate that a targeting ligand (RGD) conjugated to nanotubes significantly enhances the number of single-walled carbon nanotube-loaded monocytes reaching the tumour (P < 0.001, day 7 post-injection). The remarkable selectivity of this tumour-targeting mechanism demonstrates an advanced immune-based delivery strategy for enhancing specific tumour delivery with substantial penetration.

  4. Selective uptake of single-walled carbon nanotubes by circulating monocytes for enhanced tumour delivery

    NASA Astrophysics Data System (ADS)

    Smith, Bryan Ronain; Ghosn, Eliver Eid Bou; Rallapalli, Harikrishna; Prescher, Jennifer A.; Larson, Timothy; Herzenberg, Leonore A.; Gambhir, Sanjiv Sam

    2014-06-01

    In cancer imaging, nanoparticle biodistribution is typically visualized in living subjects using `bulk' imaging modalities such as magnetic resonance imaging, computerized tomography and whole-body fluorescence. Accordingly, nanoparticle influx is observed only macroscopically, and the mechanisms by which they target cancer remain elusive. Nanoparticles are assumed to accumulate via several targeting mechanisms, particularly extravasation (leakage into tumour). Here, we show that, in addition to conventional nanoparticle-uptake mechanisms, single-walled carbon nanotubes are almost exclusively taken up by a single immune cell subset, Ly-6Chi monocytes (almost 100% uptake in Ly-6Chi monocytes, below 3% in all other circulating cells), and delivered to the tumour in mice. We also demonstrate that a targeting ligand (RGD) conjugated to nanotubes significantly enhances the number of single-walled carbon nanotube-loaded monocytes reaching the tumour (P < 0.001, day 7 post-injection). The remarkable selectivity of this tumour-targeting mechanism demonstrates an advanced immune-based delivery strategy for enhancing specific tumour delivery with substantial penetration.

  5. Single molecule detection of 4-dimethylaminoazobenzene by surface-enhanced Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Zhang, Z. L.; Yin, Y. F.; Jiang, J. W.; Mo, Y. J.

    2009-02-01

    4-Dimethylaminoazobenzene (DAB) is anticipated to be a human carcinogen based on sufficient evidence of carcinogenicity in experimental animals. The trace detection of DAB is of great significance in environmental protection and safe life of the people. To test the availability of DAB trace detection using surface-enhanced Raman scattering (SERS), the SERS spectra of DAB single molecules adsorbed on the silver particle aggregates in colloid were investigated. The phenomena of blinking, spectral diffusion, and intensity fluctuations of the vibrational lines in the SERS spectra were observed. Statistical analysis of spectral intensity fluctuations indicates a multimodal distribution of some specific Raman bands, which are consistent with the identification of single molecule detection. Our results demonstrated that SERS can be applied to the trace detection of DAB molecules and other azo dyes.

  6. Single gold nanoparticles to enhance the detection of single fluorescent molecules at micromolar concentration using fluorescence correlation spectroscopy

    NASA Astrophysics Data System (ADS)

    Punj, Deep; Rigneault, Hervé; Wenger, Jérôme

    2014-05-01

    Single nanoparticles made of noble metals are strongly appealing to develop practical applications to detect fluorescent molecules in solution. Here, we detail the use of a single gold nanoparticle of 100 nm diameter to enhance the detection of single Alex Fluor 647 fluorescent molecules at high concentrations of several micromolar. We discuss the implementation of fluorescence correlation spectroscopy, and provide a new method to reliably extract the enhanced fluorescence signal stemming from the nanoparticle near-field from the background generated in the confocal volume. The applicability of our method is checked by reporting the invariance of the single molecule results as function of the molecular concentration, and the experimental data is found in good agreement with numerical simulations.

  7. Plasmonic nanopore-based platforms for single-molecule Raman scattering

    NASA Astrophysics Data System (ADS)

    Deng, Liang; Wang, Yixin; Liu, Chen; Hu, Dora Juan Juan; Shum, Perry Ping; Su, Lei

    2016-08-01

    We propose and demonstrate a novel plasmonic nanopore platform based on a bowtie-nanopore structure, for single-molecule sensing. In this nano-structure, nano-bowties are integrated with solid-state nanopores to provide localized surface plasmon resonances for signal enhancement. We design and optimize the nano-structure by tuning both the bowtie gap and the bowtie angle, and investigate their influences on field enhancement, thereby achieving single-molecule sensitivity. In addition, we study the field enhancement by introducing an engineered photonic nano-cavity. This further strengthens the electric enhancement. An overall Raman enhancement factor of 2×108 is achieved in our simulation. This is believed to be sufficient for single-molecule sensing. The proposed bowtie-nanopore structure can be multiplexed on a single substrate for simultaneous multi-channel detection, paving the way for demanding applications such as DNA sequencing.

  8. Photoacoustic imaging enhanced by indocyanine green-conjugated single-wall carbon nanotubes.

    PubMed

    Zanganeh, Saeid; Li, Hai; Kumavor, Patrick D; Alqasemi, Umar; Aguirre, Andres; Mohammad, Innus; Stanford, Courtney; Smith, Michael B; Zhu, Quing

    2013-09-01

    A photoacoustic contrast agent that is based on bis-carboxylic acid derivative of indocyanine green (ICG) covalently conjugated to single-wall carbon nanotubes (ICG/SWCNT) is presented. Covalently attaching ICG to the functionalized SWCNT provides a more robust system that delivers much more ICG to the tumor site. The detection sensitivity of the new contrast agent in a mouse tumor model is demonstrated in vivo by our custom-built photoacoustic imaging system. The summation of the photoacoustic tomography (PAT) beam envelope, referred to as the "PAT summation," is used to demonstrate the postinjection light absorption of tumor areas in ICG- and ICG/SWCNT-injected mice. It is shown that ICG is able to provide 33% enhancement at approximately 20 min peak response time with reference to the preinjection PAT level, while ICG/SWCNT provides 128% enhancement at 80 min and even higher enhancement of 196% at the end point of experiments (120 min on average). Additionally, the ICG/SWCNT enhancement was mainly observed at the tumor periphery, which was confirmed by fluorescence images of the tumor samples. This feature is highly valuable in guiding surgeons to assess tumor boundaries and dimensions in vivo and to achieve clean tumor margins to improve surgical resection of tumors.

  9. Surface enhanced Raman spectroscopy and quantum chemical studies on glycine single crystal

    NASA Astrophysics Data System (ADS)

    Parameswari, A.; Premkumar, S.; Premkumar, R.; Milton Franklin Benial, A.

    2016-07-01

    Adsorption characteristics of glycine (Gly) on silver surface were investigated based on density functional theory calculations and surface enhanced Raman spectroscopy (SERS) technique. The single crystals of Gly were grown by slow evaporation method and characterized by single crystal X-ray diffraction (XRD) technique. Silver nanoparticles (Ag NPs) were prepared by solution combustion method using Gly as fuel. The Ag NPs were characterized by XRD, ultraviolet-visible spectroscopy and high-resolution transmission electron microscopy techniques. The calculated structural parameters of Gly molecule were compared with the experimental observed single crystal XRD data. The structural parameters of Gly after adsorption on silver surface show the slight deviation, which indicates the interaction between the Gly and Ag3 cluster. Raman and SERS spectra for Gly single crystal were studied experimentally. Raman frequencies were calculated for Gly and Gly adsorbed on a silver surface. Raman and SERS frequencies were assigned on the basis of potential energy distribution calculation and compared with the experimental values. Frontier molecular orbital analysis was carried out for Gly and Gly adsorbed on a silver surface. The band gap value was significantly reduced for Gly after adsorption on the silver surface. The reduction in band gap indicates the delocalization of electrons, which leads to the higher bioactivity of the title molecule. SERS spectral analysis reveals that the Gly adsorbed as a stand-on orientation on the silver surface. Hence, the present investigation has been developed as a model system to understand the interaction of Ag NPs with amino acids.

  10. Localized surface plasmon resonance enhanced ultraviolet emission and F-P lasing from single ZnO microflower

    NASA Astrophysics Data System (ADS)

    Lin, Yi; Li, Jitao; Xu, Chunxiang; Fan, Xuemei; Wang, Baoping

    2014-10-01

    In this work, monodispersed ZnO microflowers are fabricated by a vapor phase transport method, and Au nanoparticles (NPs) are directly decorated on the surface of the ZnO microflowers. The micro-photoluminescence of a single ZnO microflower demonstrates that the near band-edge emission is tremendously enhanced while the defect-related emission is completely suppressed after Au decoration. The average enhancement factor reaches up to 65 fold. The enhancement mechanism is assumed to be the electron transfer from excited Au NPs to the ZnO microflower induced by the localized surface plasmon resonance based on the time-resolved photoluminescence. The enhanced F-P lasing from a single ZnO sample is further realized.

  11. Single conducting polymer nanowire based conductometric sensors

    NASA Astrophysics Data System (ADS)

    Bangar, Mangesh Ashok

    The detection of toxic chemicals, gases or biological agents at very low concentrations with high sensitivity and selectivity has been subject of immense interest. Sensors employing electrical signal readout as transduction mechanism offer easy, label-free detection of target analyte in real-time. Traditional thin film sensors inherently suffered through loss of sensitivity due to current shunting across the charge depleted/added region upon analyte binding to the sensor surface, due to their large cross sectional area. This limitation was overcome by use of nanostructure such as nanowire/tube as transducer where current shunting during sensing was almost eliminated. Due to their benign chemical/electrochemical fabrication route along with excellent electrical properties and biocompatibility, conducting polymers offer cost-effective alternative over other nanostructures. Biggest obstacle in using these nanostructures is lack of easy, scalable and cost-effective way of assembling these nanostructures on prefabricated micropatterns for device fabrication. In this dissertation, three different approaches have been taken to fabricate individual or array of single conducting polymer (and metal) nanowire based devices and using polymer by itself or after functionalization with appropriate recognition molecule they have been applied for gas and biochemical detection. In the first approach electrochemical fabrication of multisegmented nanowires with middle functional Ppy segment along with ferromagnetic nickel (Ni) and end gold segments for better electrical contact was studied. This multi-layered nanowires were used along with ferromagnetic contact electrode for controlled magnetic assembly of nanowires into devices and were used for ammonia gas sensing. The second approach uses conducting polymer, polypyrrole (Ppy) nanowires using simple electrophoretic alignment and maskless electrodeposition to anchor nanowire which were further functionalized with antibodies against

  12. Image enhancement based on gamma map processing

    NASA Astrophysics Data System (ADS)

    Tseng, Chen-Yu; Wang, Sheng-Jyh; Chen, Yi-An

    2010-05-01

    This paper proposes a novel image enhancement technique based on Gamma Map Processing (GMP). In this approach, a base gamma map is directly generated according to the intensity image. After that, a sequence of gamma map processing is performed to generate a channel-wise gamma map. Mapping through the estimated gamma, image details, colorfulness, and sharpness of the original image are automatically improved. Besides, the dynamic range of the images can be virtually expanded.

  13. Reproducing kernel hilbert space based single infrared image super resolution

    NASA Astrophysics Data System (ADS)

    Chen, Liangliang; Deng, Liangjian; Shen, Wei; Xi, Ning; Zhou, Zhanxin; Song, Bo; Yang, Yongliang; Cheng, Yu; Dong, Lixin

    2016-07-01

    The spatial resolution of Infrared (IR) images is limited by lens optical diffraction, sensor array pitch size and pixel dimension. In this work, a robust model is proposed to reconstruct high resolution infrared image via a single low resolution sampling, where the image features are discussed and classified as reflective, cooled emissive and uncooled emissive based on infrared irradiation source. A spline based reproducing kernel hilbert space and approximative heaviside function are deployed to model smooth part and edge component of image respectively. By adjusting the parameters of heaviside function, the proposed model can enhance distinct part of images. The experimental results show that the model is applicable on both reflective and emissive low resolution infrared images to improve thermal contrast. The overall outcome produces a high resolution IR image, which makes IR camera better measurement accuracy and observes more details at long distance.

  14. A single bout of resistance exercise can enhance episodic memory performance

    PubMed Central

    Weinberg, Lisa; Hasni, Anita; Shinohara, Minoru; Duarte, Audrey

    2014-01-01

    Acute aerobic exercise can be beneficial to episodic memory. This benefit may occur because exercise produces a similar physiological response as physical stressors. When administered during consolidation, acute stress, both physical and psychological, consistently enhances episodic memory, particularly memory for emotional materials. Here we investigated whether a single bout of resistance exercise performed during consolidation can produce episodic memory benefits 48 hours later. We used a one-leg knee extension/flexion task for the resistance exercise. To assess the physiological response to the exercise, we measured salivary alpha amylase (a biomarker of central norepinephrine), heart rate, and blood pressure. To test emotional episodic memory, we used a remember-know recognition memory paradigm with equal numbers of positive, negative, and neutral IAPS images as stimuli. The group that performed the exercise, the active group, had higher overall recognition accuracy than the group that did not exercise, the passive group. We found a robust effect of valence across groups, with better performance on emotional items as compared to neutral items and no difference between positive and negative items. This effect changed based on the physiological response to the exercise. Within the active group, participants with a high physiological response to the exercise were impaired for neutral items as compared to participants with a low physiological response to the exercise. Our results demonstrate that a single bout of resistance exercise performed during consolidation can enhance episodic memory and that the effect of valence on memory depends on the physiological response to the exercise. PMID:25262058

  15. A single bout of resistance exercise can enhance episodic memory performance.

    PubMed

    Weinberg, Lisa; Hasni, Anita; Shinohara, Minoru; Duarte, Audrey

    2014-11-01

    Acute aerobic exercise can be beneficial to episodic memory. This benefit may occur because exercise produces a similar physiological response as physical stressors. When administered during consolidation, acute stress, both physical and psychological, consistently enhances episodic memory, particularly memory for emotional materials. Here we investigated whether a single bout of resistance exercise performed during consolidation can produce episodic memory benefits 48 h later. We used a one-leg knee extension/flexion task for the resistance exercise. To assess the physiological response to the exercise, we measured salivary alpha amylase (a biomarker of central norepinephrine), heart rate, and blood pressure. To test emotional episodic memory, we used a remember-know recognition memory paradigm with equal numbers of positive, negative, and neutral IAPS images as stimuli. The group that performed the exercise, the active group, had higher overall recognition accuracy than the group that did not exercise, the passive group. We found a robust effect of valence across groups, with better performance on emotional items as compared to neutral items and no difference between positive and negative items. This effect changed based on the physiological response to the exercise. Within the active group, participants with a high physiological response to the exercise were impaired for neutral items as compared to participants with a low physiological response to the exercise. Our results demonstrate that a single bout of resistance exercise performed during consolidation can enhance episodic memory and that the effect of valence on memory depends on the physiological response to the exercise. PMID:25262058

  16. A single bout of resistance exercise can enhance episodic memory performance.

    PubMed

    Weinberg, Lisa; Hasni, Anita; Shinohara, Minoru; Duarte, Audrey

    2014-11-01

    Acute aerobic exercise can be beneficial to episodic memory. This benefit may occur because exercise produces a similar physiological response as physical stressors. When administered during consolidation, acute stress, both physical and psychological, consistently enhances episodic memory, particularly memory for emotional materials. Here we investigated whether a single bout of resistance exercise performed during consolidation can produce episodic memory benefits 48 h later. We used a one-leg knee extension/flexion task for the resistance exercise. To assess the physiological response to the exercise, we measured salivary alpha amylase (a biomarker of central norepinephrine), heart rate, and blood pressure. To test emotional episodic memory, we used a remember-know recognition memory paradigm with equal numbers of positive, negative, and neutral IAPS images as stimuli. The group that performed the exercise, the active group, had higher overall recognition accuracy than the group that did not exercise, the passive group. We found a robust effect of valence across groups, with better performance on emotional items as compared to neutral items and no difference between positive and negative items. This effect changed based on the physiological response to the exercise. Within the active group, participants with a high physiological response to the exercise were impaired for neutral items as compared to participants with a low physiological response to the exercise. Our results demonstrate that a single bout of resistance exercise performed during consolidation can enhance episodic memory and that the effect of valence on memory depends on the physiological response to the exercise.

  17. Enhanced oil recovery projects data base

    SciTech Connect

    Pautz, J.F.; Sellers, C.A.; Nautiyal, C.; Allison, E.

    1992-04-01

    A comprehensive enhanced oil recovery (EOR) project data base is maintained and updated at the Bartlesville Project Office of the Department of Energy. This data base provides an information resource that is used to analyze the advancement and application of EOR technology. The data base has extensive information on 1,388 EOR projects in 569 different oil fields from 1949 until the present, and over 90% of that information is contained in tables and graphs of this report. The projects are presented by EOR process, and an index by location is provided.

  18. A single point mutation enhances hydroxynitrile synthesis by halohydrin dehalogenase.

    PubMed

    Schallmey, Marcus; Jekel, Peter; Tang, Lixia; Majerić Elenkov, Maja; Höffken, Hans Wolfgang; Hauer, Bernhard; Janssen, Dick B

    2015-03-01

    The cyanide-mediated ring opening of epoxides catalyzed by halohydrin dehalogenases yields β-hydroxynitriles that are of high interest for synthetic chemistry. The best studied halohydrin dehalogenase to date is the enzyme from Agrobacterium radiobacter, but this enzyme (HheC) exhibits only low cyanolysis activities. Sequence comparison between a pair of related halohydrin dehalogenases from Corynebacterium and Mycobacterium suggested that substitution of a threonine that interacts with the active site might be responsible for the higher cyanolytic activity of the former enzyme. Here we report that a variant of HheC in which this substitution (T134A) is adopted displays an up to 11-fold higher activity in cyanide-mediated epoxide ring-opening. The mutation causes removal of the hydrogen bond between residue 134 and the side chain O of the active site serine 132, which donates a hydrogen bond to the substrate oxygen. The mutation also increases dehalogenase rates with various substrates. Structural analysis revealed that the anion-binding site of the mutant enzyme remained unaltered, showing that the enhanced activity is due to altered interactions with the substrate oxygen rather than changes in the nucleophile binding site.

  19. Enhanced Raman Microprobe Imaging of Single-Wall Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Hadjiev, V. G.; Arepalli, S.; Nikolaev, P.; Jandl, S.; Yowell, L.

    2003-01-01

    We explore Raman microprobe capabilities to visualize single wall carbon nanotubes (SWCNTs). Although this technique is limited to a micron scale, we demonstrate that images of individual SWCNTs, bundles or their agglomerates can be generated by mapping Raman active elementary excitations. We measured the Raman response from carbon vibrations in SWCNTs excited by confocal scanning of a focused laser beam. Carbon vibrations reveal key characteristics of SWCNTs as nanotube diameter distribution (radial breathing modes, RBM, 100-300 cm(exp -1)), presence of defects and functional groups (D-mode, 1300-1350 cm(exp -1)), strain and oxidation states of SWCNTs, as well as metallic or semiconducting character of the tubes encoded in the lineshape of the G-modes at 1520-1600 cm(exp - 1). In addition, SWCNTs are highly anisotropic scatterers. The Raman response from a SWCNT is maximal for incident light polarization parallel to the tube axis and vanishing for perpendicular directions. We show that the SWCNT bundle shape or direction can be determined, with some limitations, from a set of Raman images taken at two orthogonal directions of the incident light polarization.

  20. Single-mode enhancement in coupled-cavity quantum cascade lasers

    NASA Astrophysics Data System (ADS)

    Kuc, M.; Sarzała, R. P.; Czyszanowski, T.; Bugajski, M.

    2016-03-01

    This paper reports on numerical analysis of longitudinal mode discrimination in coupled-cavity AlInAs/InGaAs/InP quantum cascade lasers. Using a three dimensional, self-consistent model of physical phenomena in edge emitting laser we performed exhaustive analysis of geometrical parameters of CC QCL on spectral characteristics. We discuss the enhancement of the single mode operation in multi-section designs concerning variable dimensions of sections and air gaps between sections and provide designing guidelines assuring single-mode operation. We also show impact of independent current tuning of laser sections inducing Stark effect and heating as additional elements enhancing single mode operation.

  1. Single mode waveguide platform for spontaneous and surface-enhanced on-chip Raman spectroscopy.

    PubMed

    Dhakal, Ashim; Peyskens, Frédéric; Clemmen, Stéphane; Raza, Ali; Wuytens, Pieter; Zhao, Haolan; Le Thomas, Nicolas; Baets, Roel

    2016-08-01

    We review an on-chip approach for spontaneous Raman spectroscopy and surface-enhanced Raman spectroscopy based on evanescent excitation of the analyte as well as evanescent collection of the Raman signal using complementary metal oxide semiconductor (CMOS)-compatible single mode waveguides. The signal is either directly collected from the analyte molecules or via plasmonic nanoantennas integrated on top of the waveguides. Flexibility in the design of the geometry of the waveguide, and/or the geometry of the antennas, enables optimization of the collection efficiency. Furthermore, the sensor can be integrated with additional functionality (sources, detectors, spectrometers) on the same chip. In this paper, the basic theoretical concepts are introduced to identify the key design parameters, and some proof-of-concept experimental results are reviewed. PMID:27499842

  2. Fluorescence thermometry enhanced by the quantum coherence of single spins in diamond

    PubMed Central

    Toyli, David M.; de las Casas, Charles F.; Christle, David J.; Dobrovitski, Viatcheslav V.; Awschalom, David D.

    2013-01-01

    We demonstrate fluorescence thermometry techniques with sensitivities approaching 10 mK⋅Hz−1/2 based on the spin-dependent photoluminescence of nitrogen vacancy (NV) centers in diamond. These techniques use dynamical decoupling protocols to convert thermally induced shifts in the NV center's spin resonance frequencies into large changes in its fluorescence. By mitigating interactions with nearby nuclear spins and facilitating selective thermal measurements, these protocols enhance the spin coherence times accessible for thermometry by 45-fold, corresponding to a 7-fold improvement in the NV center’s temperature sensitivity. Moreover, we demonstrate these techniques can be applied over a broad temperature range and in both finite and near-zero magnetic field environments. This versatility suggests that the quantum coherence of single spins could be practically leveraged for sensitive thermometry in a wide variety of biological and microscale systems. PMID:23650364

  3. Single mode waveguide platform for spontaneous and surface-enhanced on-chip Raman spectroscopy.

    PubMed

    Dhakal, Ashim; Peyskens, Frédéric; Clemmen, Stéphane; Raza, Ali; Wuytens, Pieter; Zhao, Haolan; Le Thomas, Nicolas; Baets, Roel

    2016-08-01

    We review an on-chip approach for spontaneous Raman spectroscopy and surface-enhanced Raman spectroscopy based on evanescent excitation of the analyte as well as evanescent collection of the Raman signal using complementary metal oxide semiconductor (CMOS)-compatible single mode waveguides. The signal is either directly collected from the analyte molecules or via plasmonic nanoantennas integrated on top of the waveguides. Flexibility in the design of the geometry of the waveguide, and/or the geometry of the antennas, enables optimization of the collection efficiency. Furthermore, the sensor can be integrated with additional functionality (sources, detectors, spectrometers) on the same chip. In this paper, the basic theoretical concepts are introduced to identify the key design parameters, and some proof-of-concept experimental results are reviewed.

  4. A proposal and a theoretical analysis of an enhanced surface plasmon coupled emission structure for single molecule detection

    NASA Astrophysics Data System (ADS)

    Uddin, Shiekh Zia; Tanvir, Mukhlasur Rahman; Talukder, Muhammad Anisuzzaman

    2016-05-01

    We propose a structure that can be used for enhanced single molecule detection using surface plasmon coupled emission (SPCE). In the proposed structure, instead of a single metal layer on the glass prism of a typical SPCE structure for fluorescence microscopy, a metal-dielectric-metal structure is used. We theoretically show that the proposed structure significantly decreases the excitation volume of the fluorescently labeled sample, and simultaneously increases the peak SPCE intensity and SPCE power. Therefore, the signal-to-noise ratio and sensitivity of an SPCE based fluorescence microscopy system can be significantly increased using the proposed structure, which will be helpful for enhanced single molecule detection, especially, in a less pure biological sample.

  5. Speech Enhancement based on Compressive Sensing Algorithm

    NASA Astrophysics Data System (ADS)

    Sulong, Amart; Gunawan, Teddy S.; Khalifa, Othman O.; Chebil, Jalel

    2013-12-01

    There are various methods, in performance of speech enhancement, have been proposed over the years. The accurate method for the speech enhancement design mainly focuses on quality and intelligibility. The method proposed with high performance level. A novel speech enhancement by using compressive sensing (CS) is a new paradigm of acquiring signals, fundamentally different from uniform rate digitization followed by compression, often used for transmission or storage. Using CS can reduce the number of degrees of freedom of a sparse/compressible signal by permitting only certain configurations of the large and zero/small coefficients, and structured sparsity models. Therefore, CS is significantly provides a way of reconstructing a compressed version of the speech in the original signal by taking only a small amount of linear and non-adaptive measurement. The performance of overall algorithms will be evaluated based on the speech quality by optimise using informal listening test and Perceptual Evaluation of Speech Quality (PESQ). Experimental results show that the CS algorithm perform very well in a wide range of speech test and being significantly given good performance for speech enhancement method with better noise suppression ability over conventional approaches without obvious degradation of speech quality.

  6. Tailoring Plasmonic Enhanced Upconversion in Single NaYF4:Yb3+/Er3+ Nanocrystals

    PubMed Central

    Wang, Ya-Lan; Mohammadi Estakhri, Nasim; Johnson, Amber; Li, Hai-Yang; Xu, Li-Xiang; Zhang, Zhenyu; Alù, Andrea; Wang, Qu-Quan; Shih, Chih-Kang (Ken)

    2015-01-01

    By using silver nanoplatelets with a widely tunable localized surface plasmon resonance (LSPR), and their corresponding local field enhancement, here we show large manipulation of plasmonic enhanced upconversion in NaYF4:Yb3+/Er3+ nanocrystals at the single particle level. In particular, we show that when the plasmonic resonance of silver nanolplatelets is tuned to 656 nm, matching the emission wavelength, an upconversion enhancement factor ~5 is obtained. However, when the plasmonic resonance is tuned to 980 nm, matching the nanocrystal absorption wavelength, we achieve an enhancement factor of ~22 folds. The precise geometric arrangement between fluorescent nanoparticles and silver nanoplatelets allows us to make, for the first time, a comparative analysis between experimental results and numerical simulations, yielding a quantitative agreement at the single particle level. Such a comparison lays the foundations for a rational design of hybrid metal-fluorescent nanocrystals to harness the upconversion enhancement for biosensing and light harvesting applications. PMID:25976870

  7. HMX based enhanced energy LOVA gun propellant.

    PubMed

    Sanghavi, R R; Kamale, P J; Shaikh, M A R; Shelar, S D; Kumar, K Sunil; Singh, Amarjit

    2007-05-01

    Efforts to develop gun propellants with low vulnerability have recently been focused on enhancing the energy with a further improvement in its sensitivity characteristics. These propellants not only prevent catastrophic disasters due to unplanned initiation of currently used gun propellants (based on nitrate esters) but also realize enhanced energy levels to increase the muzzle velocity of the projectiles. Now, in order to replace nitroglycerine, which is highly sensitive to friction and impact, nitramines meet the requirements as they offer superior energy due to positive heat of formation, typical stoichiometry with higher decomposition temperatures and also owing to negative oxygen balance are less sensitive than stoichiometrically balanced NG. RDX has been widely reported for use in LOVA propellant. In this paper we have made an effort to present the work on scantily reported nitramine HMX based LOVA gun propellant while incorporating energetic plasticizer glycidyl azide polymer to enhance the energy level. HMX is known to be thermally stable at higher temperature than RDX and also proved to be less vulnerable to small scale shaped charge jet attack as its decomposition temperature is 270 degrees C. HMX also offers improved impulse due to its superior heat of formation (+17 kcal/mol) as compared to RDX (+14 kcal/mol). It has also been reported that a break point will not appear until 35,000 psi for propellant comprising of 5 microm HMX. Since no work has been reported in open literature regarding replacement of RDX by HMX, the present studies were carried out.

  8. Enhancing atlas based segmentation with multiclass linear classifiers

    SciTech Connect

    Sdika, Michaël

    2015-12-15

    Purpose: To present a method to enrich atlases for atlas based segmentation. Such enriched atlases can then be used as a single atlas or within a multiatlas framework. Methods: In this paper, machine learning techniques have been used to enhance the atlas based segmentation approach. The enhanced atlas defined in this work is a pair composed of a gray level image alongside an image of multiclass classifiers with one classifier per voxel. Each classifier embeds local information from the whole training dataset that allows for the correction of some systematic errors in the segmentation and accounts for the possible local registration errors. The authors also propose to use these images of classifiers within a multiatlas framework: results produced by a set of such local classifier atlases can be combined using a label fusion method. Results: Experiments have been made on the in vivo images of the IBSR dataset and a comparison has been made with several state-of-the-art methods such as FreeSurfer and the multiatlas nonlocal patch based method of Coupé or Rousseau. These experiments show that their method is competitive with state-of-the-art methods while having a low computational cost. Further enhancement has also been obtained with a multiatlas version of their method. It is also shown that, in this case, nonlocal fusion is unnecessary. The multiatlas fusion can therefore be done efficiently. Conclusions: The single atlas version has similar quality as state-of-the-arts multiatlas methods but with the computational cost of a naive single atlas segmentation. The multiatlas version offers a improvement in quality and can be done efficiently without a nonlocal strategy.

  9. Enhancement of textural differences based on morphological component analysis.

    PubMed

    Chi, Jianning; Eramian, Mark

    2015-09-01

    This paper proposes a new texture enhancement method which uses an image decomposition that allows different visual characteristics of textures to be represented by separate components in contrast with previous methods which either enhance texture indirectly or represent all texture information using a single image component. Our method is intended to be used as a preprocessing step prior to the use of texture-based image segmentation algorithms. Our method uses a modification of morphological component analysis (MCA) which allows texture to be separated into multiple morphological components each representing a different visual characteristic of texture. We select four such texture characteristics and propose new dictionaries to extract these components using MCA. We then propose procedures for modifying each texture component and recombining them to produce a texture-enhanced image. We applied our method as a preprocessing step prior to a number of texture-based segmentation methods and compared the accuracy of the results, finding that our method produced results superior to comparator methods for all segmentation algorithms tested. We also demonstrate by example the main mechanism by which our method produces superior results, namely that it causes the clusters of local texture features of each distinct image texture to mutually diverge within the multidimensional feature space to a vastly superior degree versus the comparator enhancement methods. PMID:25935032

  10. Magnetic-field-enhanced synthesis of single-wall carbon nanotubes in arc discharge

    NASA Astrophysics Data System (ADS)

    Keidar, Michael; Levchenko, Igor; Arbel, Tamir; Alexander, Myriam; Waas, Anthony M.; Ostrikov, Kostya Ken

    2008-05-01

    The ability to control the properties of single-wall nanotubes (SWNTs) produced in the arc discharge is important for many practical applications. Our experiments suggest that the length of SWNTs significantly increases (up to 4000 nm), along with the purity of the carbon deposit, when the magnetic field is applied to arc discharge. Scanning electron microscopy and transmission electron microscopy analyses have demonstrated that the carbon deposit produced in the magnetic-field-enhanced arc mainly consists of the isolated and bunched SWNTs. A model of a carbon nanotube interaction and growth in the thermal plasma was developed, which considers several important effects such as anode ablation that supplies the carbon plasma in an anodic arc discharge technique, and the momentum, charge, and energy transfer processes between nanotube and plasma. It is shown that the nanotube charge with respect to the plasma as well as nanotube length depend on plasma density and electric field in the interelectrode gap. For instance, nanotube charge changes from negative to positive value with an electron density decrease. The numerical simulations based on the Monte Carlo technique were performed, which explain an increase in the nanotubes produced in the magnetic-field-enhanced arc discharge.

  11. Enhanced photoabsorption in front-tapered single-nanowire solar cells.

    PubMed

    Zhan, Yaohui; Li, Xiaofeng; Wu, Shaolong; Li, Ke; Yang, Zhenhai; Shang, Aixue

    2014-10-01

    Vertically aligned single-nanowire is verified to be a unique building block to realize the high-efficiency solar cell beyond Schockley-Queisser limit. We proposed a front-tapered vertically aligned single-nanowire solar cell (V-SNSC) and investigated numerically the possibility of this configuration to improve the photoabsorption efficiency compared to the conventional designs, by using 2.5D full-wave finite-element method. The influences of the feature sizes of aspect ratio, bottom radius, and nanowire length on the light-trapping properties were explored; the detailed field distribution and carrier generation rate were revealed as well based on the theory of dielectric resonant antenna, in order to elucidate the underlying physical mechanism. Results showed that, compared with the cylindrical counterparts, the absorption capability of V-SNSCs could be greatly enhanced by using a front-tapered configuration with less material utilized, and that such a positive effect can be further strengthened by increasing the nanowire length. The proposed configuration provides a promising approach to engineer the photoabsorption in the photovoltaic and other optoelectronic devices.

  12. Enhanced gene repair mediated by methyl-CpG-modified single-stranded oligonucleotides

    PubMed Central

    Bertoni, Carmen; Rustagi, Arjun; Rando, Thomas A.

    2009-01-01

    Gene editing mediated by oligonucleotides has been shown to induce stable single base alterations in genomic DNA in both prokaryotic and eukaryotic organisms. However, the low frequencies of gene repair have limited its applicability for both basic manipulation of genomic sequences and for the development of therapeutic approaches for genetic disorders. Here, we show that single-stranded oligodeoxynucleotides (ssODNs) containing a methyl-CpG modification and capable of binding to the methyl-CpG binding domain protein 4 (MBD4) are able to induce >10-fold higher levels of gene correction than ssODNs lacking the specific modification. Correction was stably inherited through cell division and was confirmed at the protein, transcript and genomic levels. Downregulation of MBD4 expression using RNAi prevented the enhancement of gene correction efficacy obtained using the methyl-CpG-modified ssODN, demonstrating the specificity of the repair mechanism being recruited. Our data demonstrate that efficient manipulation of genomic targets can be achieved and controlled by the type of ssODN used and by modulation of the repair mechanism involved in the correction process. This new generation of ssODNs represents an important technological advance that is likely to have an impact on multiple applications, especially for gene therapy where permanent correction of the genetic defect has clear advantages over viral and other nonviral approaches currently being tested. PMID:19854937

  13. Resolving the electromagnetic mechanism of surface-enhanced light scattering at single hot spots

    PubMed Central

    Alonso-González, P.; Albella, P.; Schnell, M.; Chen, J.; Huth, F.; García-Etxarri, A.; Casanova, F.; Golmar, F.; Arzubiaga, L.; Hueso, L.E.; Aizpurua, J.; Hillenbrand, R.

    2012-01-01

    Light scattering at nanoparticles and molecules can be dramatically enhanced in the 'hot spots' of optical antennas, where the incident light is highly concentrated. Although this effect is widely applied in surface-enhanced optical sensing, spectroscopy and microscopy, the underlying electromagnetic mechanism of the signal enhancement is challenging to trace experimentally. Here we study elastically scattered light from an individual object located in the well-defined hot spot of single antennas, as a new approach to resolve the role of the antenna in the scattering process. We provide experimental evidence that the intensity elastically scattered off the object scales with the fourth power of the local field enhancement provided by the antenna, and that the underlying electromagnetic mechanism is identical to the one commonly accepted in surface-enhanced Raman scattering. We also measure the phase shift of the scattered light, which provides a novel and unambiguous fingerprint of surface-enhanced light scattering. PMID:22353715

  14. Reactive ion etching-assisted surface-enhanced Raman scattering measurements on the single nanoparticle level

    SciTech Connect

    Wang, Si-Yi; Jiang, Xiang-Xu; Wei, Xin-Pan; Lee, Shuit-Tong E-mail: yaohe@suda.edu.cn; He, Yao E-mail: yaohe@suda.edu.cn; Xu, Ting-Ting

    2014-06-16

    Single-nanoparticle surface-enhanced Raman scattering (SERS) measurement is of essential importance for both fundamental research and practical applications. In this work, we develop a class of single-particle SERS approaches, i.e., reactive ion etching (RIE)-assisted SERS measurements correlated with scanning electron microscopy (SEM) strategy (RIE/SERS/SEM), enabling precise and high-resolution identification of single gold nanoparticle (AuNP) in facile and reliable manners. By using AuNP-coated silicon wafer and quartz glass slide as models, we further employ the developed RIE/SERS/SEM method for interrogating the relationship between SERS substrates and enhancement factor (EF) on the single particle level. Together with theoretical calculation using an established finite-difference-time-domain (FDTD) method, we demonstrate silicon wafer as superior SERS substrates, facilitating improvement of EF values.

  15. Microprocessor-based single particle calibration of scintillation counter

    NASA Technical Reports Server (NTRS)

    Mazumdar, G. K. D.; Pathak, K. M.

    1985-01-01

    A microprocessor-base set-up is fabricated and tested for the single particle calibration of the plastic scintillator. The single particle response of the scintillator is digitized by an A/D converter, and a 8085 A based microprocessor stores the pulse heights. The digitized information is printed. Facilities for CRT display and cassette storing and recalling are also made available.

  16. Strongly enhanced Raman scattering of graphene by a single gold nanorod

    SciTech Connect

    He, Yingbo; Shen, Hongming; Cheng, Yuqing; Lu, Guowei Gong, Qihuang

    2015-08-03

    Individual gold nanorods (AuNRs) and monolayer graphene hybrid system is investigated experimentally. Surface enhanced Raman scattering (SERS) signal of the graphene is observed due to a single AuNR with enhancement factor up to ∼1000-fold. The SERS intensity is strongly polarization dependent and the enhancement effect varies with the detuning between the excitation laser and the AuNR resonance. The SERS effect is highest when the resonant wavelength of the AuNRs matches well with the excitation light. By correlating the scattering and photoluminescence, it is demonstrated that the conventional background in SERS ascribes to the photon emission of metallic nanostructures.

  17. Direct Measurement of Single-Molecule DNA Hybridization Dynamics with Single-Base Resolution.

    PubMed

    He, Gen; Li, Jie; Ci, Haina; Qi, Chuanmin; Guo, Xuefeng

    2016-07-25

    Herein, we report label-free detection of single-molecule DNA hybridization dynamics with single-base resolution. By using an electronic circuit based on point-decorated silicon nanowires as electrical probes, we directly record the folding/unfolding process of individual hairpin DNAs with sufficiently high signal-to-noise ratio and bandwidth. These measurements reveal two-level current oscillations with strong temperature dependence, enabling us to determine the thermodynamic and kinetic properties of hairpin DNA hybridization. More importantly, successive, stepwise increases and decreases in device conductance at low temperature on a microsecond timescale are successfully observed, indicating a base-by-base unfolding/folding process. The process demonstrates a kinetic zipper model for DNA hybridization/dehybridization at the single base-pair level. This measurement capability promises a label-free single-molecule approach to probe biomolecular interactions with fast dynamics.

  18. Room-temperature single-photon sources based on nanocrystal fluorescence in photonic/plasmonic nanostructures

    NASA Astrophysics Data System (ADS)

    Lukishova, S. G.; Winkler, J. M.; Bissell, L. J.; Mihaylova, D.; Liapis, Andreas C.; Shi, Z.; Goldberg, D.; Menon, V. M.; Boyd, R. W.; Chen, G.; Prasad, P.

    2014-10-01

    Results are presented here towards robust room-temperature SPSs based on fluorescence in nanocrystals: colloidal quantum dots, color-center diamonds and doped with trivalent rare-earth ions (TR3+). We used cholesteric chiral photonic bandgap and Bragg-reflector microcavities for single emitter fluorescence enhancement. We also developed plasmonic bowtie nanoantennas and 2D-Si-photonic bandgap microcavities. The paper also provides short outlines of other technologies for room-temperature single-photon sources.

  19. Feasibility of Single Molecule DNA Sequencing using Surface-Enhanced Raman Scattering

    SciTech Connect

    Talley, C E; Reboredo, F; Chan, J; Lane, S M

    2006-02-03

    We have used a combined theoretical and experimental approach in order to assess the feasibility of using surface-enhanced Raman scattering (SERS) for DNA sequencing at the single molecule level. We have developed a numerical tool capable of calculating the E-field and resulting SERS enhancement factors for metallic structures of arbitrary size and shape. Measurements of the additional SERS enhancement by combining SERS with coherent antistokes Raman scattering (CARS) show that only modest increases in the signal are achievable due to thermal damage at higher laser powers. Finally, measurements of the SERS enhancement from nanoparticles coated with an insulating layer show that the SERS enhancement is decreased by as much as two orders of magnitude when the molecule is not in contact with the metal surface.

  20. Single-tube fluorescent product-enhanced reverse transcriptase assay with Ampliwax (STF-PERT) for retrovirus quantitation.

    PubMed

    Sears, Johnna F; Khan, Arifa S

    2003-03-01

    A TaqMan fluorescent probe-based product enhanced reverse transcriptase (RT) assay is described in which the RT and polymerase chain reaction (PCR) steps are set-up in a single tube, in two compartments separated by Ampliwax (designated as single-tube fluorescent product-enhanced reverse transcriptase assay (STF-PERT)). This simplification of the two-step method resulted in increased assay reproducibility and handling efficiency while maintaining the sensitivity of the PERT assay (<10 virions). The STF-PERT assay can be used to quantitate low amounts of retrovirus in clinical and research materials and to evaluate retrovirus contamination in cell substrates and biological products in human use.

  1. Glucocorticoids enhance extinction-based psychotherapy

    PubMed Central

    de Quervain, Dominique J.-F.; Bentz, Dorothée; Michael, Tanja; Bolt, Olivia C.; Wiederhold, Brenda K.; Margraf, Jürgen; Wilhelm, Frank H.

    2011-01-01

    Behavioral exposure therapy of anxiety disorders is believed to rely on fear extinction. Because preclinical studies have shown that glucocorticoids can promote extinction processes, we aimed at investigating whether the administration of these hormones might be useful in enhancing exposure therapy. In a randomized, double-blind, placebo-controlled study, 40 patients with specific phobia for heights were treated with three sessions of exposure therapy using virtual reality exposure to heights. Cortisol (20 mg) or placebo was administered orally 1 h before each of the treatment sessions. Subjects returned for a posttreatment assessment 3–5 d after the last treatment session and for a follow-up assessment after 1 mo. Adding cortisol to exposure therapy resulted in a significantly greater reduction in fear of heights as measured with the acrophobia questionnaire (AQ) both at posttreatment and at follow-up, compared with placebo. Furthermore, subjects receiving cortisol showed a significantly greater reduction in acute anxiety during virtual exposure to a phobic situation at posttreatment and a significantly smaller exposure-induced increase in skin conductance level at follow-up. The present findings indicate that the administration of cortisol can enhance extinction-based psychotherapy. PMID:21444799

  2. Glucocorticoids enhance extinction-based psychotherapy.

    PubMed

    de Quervain, Dominique J-F; Bentz, Dorothée; Michael, Tanja; Bolt, Olivia C; Wiederhold, Brenda K; Margraf, Jürgen; Wilhelm, Frank H

    2011-04-19

    Behavioral exposure therapy of anxiety disorders is believed to rely on fear extinction. Because preclinical studies have shown that glucocorticoids can promote extinction processes, we aimed at investigating whether the administration of these hormones might be useful in enhancing exposure therapy. In a randomized, double-blind, placebo-controlled study, 40 patients with specific phobia for heights were treated with three sessions of exposure therapy using virtual reality exposure to heights. Cortisol (20 mg) or placebo was administered orally 1 h before each of the treatment sessions. Subjects returned for a posttreatment assessment 3-5 d after the last treatment session and for a follow-up assessment after 1 mo. Adding cortisol to exposure therapy resulted in a significantly greater reduction in fear of heights as measured with the acrophobia questionnaire (AQ) both at posttreatment and at follow-up, compared with placebo. Furthermore, subjects receiving cortisol showed a significantly greater reduction in acute anxiety during virtual exposure to a phobic situation at posttreatment and a significantly smaller exposure-induced increase in skin conductance level at follow-up. The present findings indicate that the administration of cortisol can enhance extinction-based psychotherapy.

  3. Single crystalline tantalum oxychloride microcubes: controllable synthesis, formation mechanism and enhanced photocatalytic hydrogen production activity.

    PubMed

    Tu, Hao; Xu, Leilei; Mou, Fangzhi; Guan, Jianguo

    2015-08-11

    Single crystalline microcubes of a new tantalum compound, tantalum oxychloride (TaO2.18Cl0.64), have been fabricated hydrothermally in a concentrated aqueous solution of hydrochloric acid and acetic acid. They contain a superstructure and exhibit remarkably enhanced photocatalytic activities for hydrogen production due to the improved light harvest and facilitated charge transport.

  4. Evaluation of a Single-Session Brief Motivational Enhancement Intervention for Partner Abusive Men

    ERIC Educational Resources Information Center

    Crane, Cory A.; Eckhardt, Christopher I.

    2013-01-01

    The current study evaluated the efficacy of a single-session brief motivational enhancement (BME) interview to increase treatment compliance and reduce recidivism rates in a sample of 82 recently adjudicated male perpetrators of intimate partner violence (IPV). Batterer intervention program attendance and completion as well as re-arrest records…

  5. Strong antenna-enhanced fluorescence of a single light-harvesting complex shows photon antibunching.

    PubMed

    Wientjes, Emilie; Renger, Jan; Curto, Alberto G; Cogdell, Richard; van Hulst, Niek F

    2014-06-23

    The nature of the highly efficient energy transfer in photosynthetic light-harvesting complexes is a subject of intense research. Unfortunately, the low fluorescence efficiency and limited photostability hampers the study of individual light-harvesting complexes at ambient conditions. Here we demonstrate an over 500-fold fluorescence enhancement of light-harvesting complex 2 (LH2) at the single-molecule level by coupling to a gold nanoantenna. The resonant antenna produces an excitation enhancement of circa 100 times and a fluorescence lifetime shortening to ~20 ps. The radiative rate enhancement results in a 5.5-fold-improved fluorescence quantum efficiency. Exploiting the unique brightness, we have recorded the first photon antibunching of a single light-harvesting complex under ambient conditions, showing that the 27 bacteriochlorophylls coordinated by LH2 act as a non-classical single-photon emitter. The presented bright antenna-enhanced LH2 emission is a highly promising system to study energy transfer and the role of quantum coherence at the level of single complexes.

  6. Goethite colloid enhanced Pu transport through a single saturated fracture in granite.

    PubMed

    Lin, Jianfeng; Dang, Haijun; Xie, Jinchuan; Li, Mei; Zhou, Guoqing; Zhang, Jihong; Zhang, Haitao; Yi, Xiaowei

    2014-08-01

    α-FeOOH, a stable iron oxide in nature, can strongly absorb the low-solubility plutonium (Pu) in aquifers. However, whether Pu transports though a single saturated fracture can be enhanced in the presence of α-FeOOH colloids remains unknown. Experimental studies were carried out to evaluate Pu mobilization at different water flow velocity, as affected by goethite colloids with various concentrations. Goethite nanorods were used to prepare (α-FeOOH)-associated Pu suspensions with α-FeOOH concentration of (0-150) mgL(-1). The work experimentally evidenced that α-FeOOH colloid does enhance transport of Pu through fractured granites. The fraction of mobile (239)Pu (RPu, m=41.5%) associated with the α-FeOOH of an extremely low colloid concentration (0.2mgL(-1)) is much larger than that in absence of α-FeOOH (RPu, m=6.98%). However, plutonium mobility began to decrease when α-FeOOH concentration was increased to 1.0mgL(-1). On the other hand, the fraction of mobile Pu increased gradually with the water flow velocity. Based on the experimental data, the mechanisms underlying the (α-FeOOH)-associated plutonium transport are comprehensively discussed in view of its dynamic deposition onto the granite surfaces, which is decided mainly by the relative interaction between the colloid particle and the immobile surface. This interaction is a balance of electrostatic force (may be repulsive or attractive), the van der Walls force, and the shear stress of flow. PMID:25016587

  7. Goethite colloid enhanced Pu transport through a single saturated fracture in granite.

    PubMed

    Lin, Jianfeng; Dang, Haijun; Xie, Jinchuan; Li, Mei; Zhou, Guoqing; Zhang, Jihong; Zhang, Haitao; Yi, Xiaowei

    2014-08-01

    α-FeOOH, a stable iron oxide in nature, can strongly absorb the low-solubility plutonium (Pu) in aquifers. However, whether Pu transports though a single saturated fracture can be enhanced in the presence of α-FeOOH colloids remains unknown. Experimental studies were carried out to evaluate Pu mobilization at different water flow velocity, as affected by goethite colloids with various concentrations. Goethite nanorods were used to prepare (α-FeOOH)-associated Pu suspensions with α-FeOOH concentration of (0-150) mgL(-1). The work experimentally evidenced that α-FeOOH colloid does enhance transport of Pu through fractured granites. The fraction of mobile (239)Pu (RPu, m=41.5%) associated with the α-FeOOH of an extremely low colloid concentration (0.2mgL(-1)) is much larger than that in absence of α-FeOOH (RPu, m=6.98%). However, plutonium mobility began to decrease when α-FeOOH concentration was increased to 1.0mgL(-1). On the other hand, the fraction of mobile Pu increased gradually with the water flow velocity. Based on the experimental data, the mechanisms underlying the (α-FeOOH)-associated plutonium transport are comprehensively discussed in view of its dynamic deposition onto the granite surfaces, which is decided mainly by the relative interaction between the colloid particle and the immobile surface. This interaction is a balance of electrostatic force (may be repulsive or attractive), the van der Walls force, and the shear stress of flow.

  8. Enhanced permeation of single-file water molecules across a noncylindrical nanochannel

    NASA Astrophysics Data System (ADS)

    Meng, X. W.; Huang, J. P.

    2013-07-01

    We utilize molecular dynamics simulations to study the effect of noncylindrical shapes of a nanochannel (which are inspired from the shape of real biological water nanochannels) on the permeation of single-file water molecules across the nanochannel. Compared with the cylindrical shape that has been tremendously adopted in the literature, the noncylindrical shapes play a crucial role in enhancing water permeation. Remarkably, the maximal enhancement ratio reaches a value of 6.28 (enhancement behavior). Meanwhile, the enhancement becomes saturated when the volume of the noncylindrical shape continues to increase (saturation behavior). The analysis of average diffusivity of water molecules helps to reveal the mechanism underlying the two behaviors whereas Poiseuille's law fails to explain them. These results pave a way for designing high-flow nanochannels and provide insight into water permeation across biological water nanochannels.

  9. Enhanced permeation of single-file water molecules across a noncylindrical nanochannel.

    PubMed

    Meng, X W; Huang, J P

    2013-07-01

    We utilize molecular dynamics simulations to study the effect of noncylindrical shapes of a nanochannel (which are inspired from the shape of real biological water nanochannels) on the permeation of single-file water molecules across the nanochannel. Compared with the cylindrical shape that has been tremendously adopted in the literature, the noncylindrical shapes play a crucial role in enhancing water permeation. Remarkably, the maximal enhancement ratio reaches a value of 6.28 (enhancement behavior). Meanwhile, the enhancement becomes saturated when the volume of the noncylindrical shape continues to increase (saturation behavior). The analysis of average diffusivity of water molecules helps to reveal the mechanism underlying the two behaviors whereas Poiseuille's law fails to explain them. These results pave a way for designing high-flow nanochannels and provide insight into water permeation across biological water nanochannels.

  10. Enhancing the Scientific Credibility of Single-Case Intervention Research: Randomization to the Rescue

    ERIC Educational Resources Information Center

    Kratochwill, Thomas R.; Levin, Joel R.

    2010-01-01

    In recent years, single-case designs have increasingly been used to establish an empirical basis for evidence-based interventions and techniques in a variety of disciplines, including psychology and education. Although traditional single-case designs have typically not met the criteria for a randomized controlled trial relative to conventional…

  11. Purity-enhanced bulk synthesis of thin single-wall carbon nanotubes using iron-copper catalysts.

    PubMed

    Lim, H E; Miyata, Y; Nakayama, T; Chen, S; Kitaura, R; Shinohara, H

    2011-09-30

    We report high purity and high yield synthesis of single-wall carbon nanotubes (SWCNTs) of narrow diameter from iron-copper bimetal catalysts. The SWCNTs with diameter of 0.8-1.2 nm are synthesized using the zeolite-supported alcohol chemical vapour deposition method. Single metal and bimetal catalysts are systematically investigated to achieve both the enhancement of SWCNT yield and the suppression of the undesired formation of graphitic impurities. The relative yield and purity of SWCNTs are quantified using optical absorption spectroscopy with an ultracentrifuge-based purification technique. For the single metal catalyst, iron shows the highest catalytic activity compared with the other metals such as cobalt, nickel, molybdenum, copper, and platinum. It has been found that the addition of copper to iron results in the suppression of carbonaceous impurity formation without decreasing the SWCNT yield. The purity-enhanced SWCNT shows fairly low sheet resistance due to the improvement of inter-nanotube contacts. This scalable design of SWCNT synthesis with enhanced purity is therefore a promising tool for shaping future high performance devices. PMID:21891846

  12. Purity-enhanced bulk synthesis of thin single-wall carbon nanotubes using iron-copper catalysts

    NASA Astrophysics Data System (ADS)

    Lim, H. E.; Miyata, Y.; Nakayama, T.; Chen, S.; Kitaura, R.; Shinohara, H.

    2011-09-01

    We report high purity and high yield synthesis of single-wall carbon nanotubes (SWCNTs) of narrow diameter from iron-copper bimetal catalysts. The SWCNTs with diameter of 0.8-1.2 nm are synthesized using the zeolite-supported alcohol chemical vapour deposition method. Single metal and bimetal catalysts are systematically investigated to achieve both the enhancement of SWCNT yield and the suppression of the undesired formation of graphitic impurities. The relative yield and purity of SWCNTs are quantified using optical absorption spectroscopy with an ultracentrifuge-based purification technique. For the single metal catalyst, iron shows the highest catalytic activity compared with the other metals such as cobalt, nickel, molybdenum, copper, and platinum. It has been found that the addition of copper to iron results in the suppression of carbonaceous impurity formation without decreasing the SWCNT yield. The purity-enhanced SWCNT shows fairly low sheet resistance due to the improvement of inter-nanotube contacts. This scalable design of SWCNT synthesis with enhanced purity is therefore a promising tool for shaping future high performance devices.

  13. Single-Photon Avalanche Diode with Enhanced NIR-Sensitivity for Automotive LIDAR Systems.

    PubMed

    Takai, Isamu; Matsubara, Hiroyuki; Soga, Mineki; Ohta, Mitsuhiko; Ogawa, Masaru; Yamashita, Tatsuya

    2016-01-01

    A single-photon avalanche diode (SPAD) with enhanced near-infrared (NIR) sensitivity has been developed, based on 0.18 μm CMOS technology, for use in future automotive light detection and ranging (LIDAR) systems. The newly proposed SPAD operating in Geiger mode achieves a high NIR photon detection efficiency (PDE) without compromising the fill factor (FF) and a low breakdown voltage of approximately 20.5 V. These properties are obtained by employing two custom layers that are designed to provide a full-depletion layer with a high electric field profile. Experimental evaluation of the proposed SPAD reveals an FF of 33.1% and a PDE of 19.4% at 870 nm, which is the laser wavelength of our LIDAR system. The dark count rate (DCR) measurements shows that DCR levels of the proposed SPAD have a small effect on the ranging performance, even if the worst DCR (12.7 kcps) SPAD among the test samples is used. Furthermore, with an eye toward vehicle installations, the DCR is measured over a wide temperature range of 25-132 °C. The ranging experiment demonstrates that target distances are successfully measured in the distance range of 50-180 cm. PMID:27043569

  14. Single-Photon Avalanche Diode with Enhanced NIR-Sensitivity for Automotive LIDAR Systems.

    PubMed

    Takai, Isamu; Matsubara, Hiroyuki; Soga, Mineki; Ohta, Mitsuhiko; Ogawa, Masaru; Yamashita, Tatsuya

    2016-03-30

    A single-photon avalanche diode (SPAD) with enhanced near-infrared (NIR) sensitivity has been developed, based on 0.18 μm CMOS technology, for use in future automotive light detection and ranging (LIDAR) systems. The newly proposed SPAD operating in Geiger mode achieves a high NIR photon detection efficiency (PDE) without compromising the fill factor (FF) and a low breakdown voltage of approximately 20.5 V. These properties are obtained by employing two custom layers that are designed to provide a full-depletion layer with a high electric field profile. Experimental evaluation of the proposed SPAD reveals an FF of 33.1% and a PDE of 19.4% at 870 nm, which is the laser wavelength of our LIDAR system. The dark count rate (DCR) measurements shows that DCR levels of the proposed SPAD have a small effect on the ranging performance, even if the worst DCR (12.7 kcps) SPAD among the test samples is used. Furthermore, with an eye toward vehicle installations, the DCR is measured over a wide temperature range of 25-132 °C. The ranging experiment demonstrates that target distances are successfully measured in the distance range of 50-180 cm.

  15. Single-Photon Avalanche Diode with Enhanced NIR-Sensitivity for Automotive LIDAR Systems

    PubMed Central

    Takai, Isamu; Matsubara, Hiroyuki; Soga, Mineki; Ohta, Mitsuhiko; Ogawa, Masaru; Yamashita, Tatsuya

    2016-01-01

    A single-photon avalanche diode (SPAD) with enhanced near-infrared (NIR) sensitivity has been developed, based on 0.18 μm CMOS technology, for use in future automotive light detection and ranging (LIDAR) systems. The newly proposed SPAD operating in Geiger mode achieves a high NIR photon detection efficiency (PDE) without compromising the fill factor (FF) and a low breakdown voltage of approximately 20.5 V. These properties are obtained by employing two custom layers that are designed to provide a full-depletion layer with a high electric field profile. Experimental evaluation of the proposed SPAD reveals an FF of 33.1% and a PDE of 19.4% at 870 nm, which is the laser wavelength of our LIDAR system. The dark count rate (DCR) measurements shows that DCR levels of the proposed SPAD have a small effect on the ranging performance, even if the worst DCR (12.7 kcps) SPAD among the test samples is used. Furthermore, with an eye toward vehicle installations, the DCR is measured over a wide temperature range of 25–132 °C. The ranging experiment demonstrates that target distances are successfully measured in the distance range of 50–180 cm. PMID:27043569

  16. OVERVIEW OF ENHANCED HANFORD SINGLE-SHELL TANK (SST) INTEGRITY PROJECT - 12128

    SciTech Connect

    VENETZ TJ; BOOMER KD; WASHENFELDER DJ; JOHNSON JB

    2012-01-25

    To improve the understanding of the single-shell tanks integrity, Washington River Protection Solutions, LLC, the USDOE Hanford Site tank contractor, developed an enhanced Single-Shell Tank (SST) Integrity Project in 2009. An expert panel on SST integrity, consisting of various subject matters experts in industry and academia, was created to provide recommendations supporting the development of the project. This panel developed 33 recommendations in four main areas of interest: structural integrity, liner degradation, leak integrity and prevention, and mitigation of contamination migration, Seventeen of these recommendations were used to develop the basis for the M-45-10-1 Change Package for the Hanford Federal Agreement and Compliance Order, which is also known as the Tri-Party Agreement. The change package identified two phases of work for SST integrity. The initial phase has been focused on efforts to envelope the integrity of the tanks. The initial phase was divided into two primary areas of investigation: structural integrity and leak integrity. If necessary based on the outcome from the initial work, a second phase would be focused on further definition of the integrity of the concrete and liners. Combined these two phases are designed to support the formal integrity assessment of the Hanford SSTs in 2018 by Independent Qualified Registered Engineer. The work to further define the DOE's understanding of the structural integrity SSTs involves preparing a modern Analysis of Record using a finite element analysis program. Structural analyses of the SSTs have been conducted since 1957, but these analyses used analog calculation, less rigorous models, or focused on individual structures. As such, an integrated understanding of all of the SSTs has not been developed to modern expectations. In support of this effort, other milestones will address the visual inspection of the tank concrete and the collection of concrete core samples from the tanks for analysis of

  17. Strong antenna-enhanced fluorescence of a single light-harvesting complex shows photon antibunching

    PubMed Central

    Wientjes, Emilie; Renger, Jan; Curto, Alberto G.; Cogdell, Richard; van Hulst, Niek F.

    2014-01-01

    The nature of the highly efficient energy transfer in photosynthetic light-harvesting complexes is a subject of intense research. Unfortunately, the low fluorescence efficiency and limited photostability hampers the study of individual light-harvesting complexes at ambient conditions. Here we demonstrate an over 500-fold fluorescence enhancement of light-harvesting complex 2 (LH2) at the single-molecule level by coupling to a gold nanoantenna. The resonant antenna produces an excitation enhancement of circa 100 times and a fluorescence lifetime shortening to ~\

  18. Non-Debye enhancements in the Mie scattering of light from a single water droplet.

    PubMed

    Lock, J A; Woodruff, J R

    1989-02-01

    The glare spots usually seen on a single water droplet which has been illuminated by a plane wave are produced by geometrical rays which correspond to the different terms of the Debye series expansion of the Mie scattered field. Recently other glare spot enhancements have been predicted which correspond to scattering resonances coupling to the orbiting rays associated with high-order geometrical rainbows. We observed the non-Debye enhancement of the eleventh-order rainbow glare spot at an observation angle of 90 degrees on a 3.5-mm water droplet illuminated by polarized He-Ne laser light. PMID:20548514

  19. Nanoimplantation and Purcell enhancement of single nitrogen-vacancy centers in photonic crystal cavities in diamond

    NASA Astrophysics Data System (ADS)

    Riedrich-Möller, Janine; Pezzagna, Sébastien; Meijer, Jan; Pauly, Christoph; Mücklich, Frank; Markham, Matthew; Edmonds, Andrew M.; Becher, Christoph

    2015-06-01

    We present the controlled creation of single nitrogen-vacancy (NV) centers via ion implantation at the center of a photonic crystal cavity which is fabricated in an ultrapure, single crystal diamond membrane. High-resolution placement of NV centers is achieved using collimation of a 5 keV-nitrogen ion beam through a pierced tip of an atomic force microscope. We demonstrate coupling of the implanted NV centers' broad band fluorescence to a cavity mode and observe Purcell enhancement of the spontaneous emission. The results are in good agreement with a master equation model for the cavity coupling.

  20. Assembling single gold nanorods into large-scale highly aligned nanoarrays via vacuum-enhanced capillarity.

    PubMed

    Wang, Jiaojiao; Li, Min; Tang, Bochong; Xie, Peng; Ma, Lei; Hu, Zhongbo; Zhao, Yuliang; Wei, Zhongqing

    2014-01-01

    We report a simple, straightforward, and efficient approach to assemble single gold nanorods (AuNRs) into highly aligned arrays, via a unique vacuum-enhanced capillarity. The assembled AuNR arrays demonstrate both an excellently unidirectional ordering and a wonderful single-rod resolution. The key role of vacuum in this approach enables high-aspect-ratio (10 to 22) AuNR alignment and efficiently facilitates large-area alignment. Further investigation of one- and two-dimensional AuNR arrays would undoubtedly be beneficial to their potential applications.

  1. Assembling single gold nanorods into large-scale highly aligned nanoarrays via vacuum-enhanced capillarity

    PubMed Central

    2014-01-01

    We report a simple, straightforward, and efficient approach to assemble single gold nanorods (AuNRs) into highly aligned arrays, via a unique vacuum-enhanced capillarity. The assembled AuNR arrays demonstrate both an excellently unidirectional ordering and a wonderful single-rod resolution. The key role of vacuum in this approach enables high-aspect-ratio (10 to 22) AuNR alignment and efficiently facilitates large-area alignment. Further investigation of one- and two-dimensional AuNR arrays would undoubtedly be beneficial to their potential applications. PMID:25313304

  2. Single-Atom Pt as Co-Catalyst for Enhanced Photocatalytic H2 Evolution.

    PubMed

    Li, Xiaogang; Bi, Wentuan; Zhang, Lei; Tao, Shi; Chu, Wangsheng; Zhang, Qun; Luo, Yi; Wu, Changzheng; Xie, Yi

    2016-03-23

    Isolated single-atom platinum (Pt) embedded in the sub-nanoporosity of 2D g-C3 N4 as a new form of co-catalyst is reported. The highly stable single-atom co-catalyst maximizes the atom efficiency and alters the surface trap states of g-C3 N4 , leading to significantly enhanced photocatalytic H2 evolution activity, 8.6 times higher than that of Pt nanoparticles and up to 50 times that for bare g-C3 N4 .

  3. Nanoimplantation and Purcell enhancement of single nitrogen-vacancy centers in photonic crystal cavities in diamond

    SciTech Connect

    Riedrich-Möller, Janine; Becher, Christoph; Pezzagna, Sébastien; Meijer, Jan; Pauly, Christoph; Mücklich, Frank; Markham, Matthew; Edmonds, Andrew M.

    2015-06-01

    We present the controlled creation of single nitrogen-vacancy (NV) centers via ion implantation at the center of a photonic crystal cavity which is fabricated in an ultrapure, single crystal diamond membrane. High-resolution placement of NV centers is achieved using collimation of a 5 keV-nitrogen ion beam through a pierced tip of an atomic force microscope. We demonstrate coupling of the implanted NV centers' broad band fluorescence to a cavity mode and observe Purcell enhancement of the spontaneous emission. The results are in good agreement with a master equation model for the cavity coupling.

  4. Introducing an enhanced recovery after surgery program in colorectal surgery: A single center experience

    PubMed Central

    Bona, Stefano; Molteni, Mattia; Rosati, Riccardo; Elmore, Ugo; Bagnoli, Pietro; Monzani, Roberta; Caravaca, Monica; Montorsi, Marco

    2014-01-01

    AIM: To study the implementation of an enhanced recovery after surgery (ERAS) program at a large University Hospital from “pilot study” to “standard of care”. METHODS: The study was designed as a prospective single centre cohort study. A prospective evaluation of compliance to a protocol based on full application of all ERAS principles, through the progressive steps of its implementation, was performed. Results achieved in the initial pilot study conducted by a dedicated team (n = 47) were compared to those achieved in the shared protocol phase (n = 143) three years later. Outcomes were length of postoperative hospital stay, readmission rate, compliance to the protocol and morbidity. Primary endpoint was the description of the results and the identification of critical issues of large scale implementation of an ERAS program in colorectal surgery emerged in the experience of a single center. Secondary endpoint was the identification of interventions that have been proven to be effective for facilitating the transition from traditional care pathways to a multimodal management protocol according to ERAS principles in colorectal surgery at a single center. RESULTS: During the initial pilot study (March 2009 to December 2010; 47 patients) conducted by a dedicated multidisciplinary team, compliance to the items of ERAS protocol was 93%, with a median length of hospital stay (LOS) of 3 d. Early anastomotic fistulas were observed in 2 cases (4.2%), which required reoperation (Clavien-Dindo grade IIIb). None of the patients had been discharged before the onset of the complication, which could therefore receive prompt treatment. There were also four (8.5%) minor complications (Clavien-Dindo grade II). Thirty days readmission rate was 4%. Perioperative mortality was nil. After implementation of the protocol throughout the Hospital in unselected patients (May 2012 to December 2012; 147 patients) compliance was 74%, with a median LOS of 6 d. Early anastomotic fistulas

  5. Enhancement of data rates by single and double cavity holographic recording

    NASA Astrophysics Data System (ADS)

    Miller, Bo E.; Takashima, Yuzuru

    2015-08-01

    To satisfy the growing need for faster archival data storage and retrieval, we proposed an improvement to the read and write data transfer rates of Holographic Data Storage Systems (HDSS). Conventionally, reading and writing of data utilize only a fraction of the available light. Our techniques apply a resonator cavity to the readout and recording of holograms so that more of the available light is used. Functionally, more power is used than what is provided without violating energy conservation. Thus, data rates and/or capacities can be increased due to enhanced power. These improvements are also inversely related to the diffraction efficiency of a hologram, which makes these cavity enhanced techniques well suited to HDSS where large numbers of multiplexed holograms require low diffraction efficiencies. Previously, we presented the theory of cavity enhanced HDSS, the experimental effect of enhancement on readout, and the lack of effects on Bragg Selectivity. We have now formalized the enhancement in writing power and experimentally evaluated the improvement in writing speed over conventional means for writing a single plane wave hologram in Fe:LiNbO3 with a 532 nm wavelength, CW, single mode, DPSS, Nd:YAG, laser with a cavity on one of the writing arms. The diffraction efficiency was read during the recording by using a 632.8 nm wavelength HeNe Laser. We found that the enhancement of recording power for this configuration asymptotically approaches a factor of two, while the use of cavities in both writing arms provides a power enhancement which is limited only by the losses in the cavities.

  6. Hybrid plasmonic-photonic mode in a subwavelength fiber for enhanced single-nanoparticle detection

    NASA Astrophysics Data System (ADS)

    Chen, You-Ling; Gong, Qihuang

    2015-01-01

    We study a hybrid mode in a composite system consisting of a localized metal nanosphere on a subwavelength fiber. It is found that the hybrid mode resulting from coupling of the fiber propagating mode and the plasmonic resonance is promising for strongly enhanced interaction between light and matter. We then propose a single-nanoparticle detection scheme by monitoring the nanofiber transmission change induced by the plasmonic-enhanced target scattering. The detection limit can be as low as 18 nm in target diameter, showing great potential for sensing single viruses or biomolecules. In the hybrid system, the resonant wavelength is tunable from visible to near-infrared spectral range by employing a metal nanoshell instead of the nanosphere, while the low detection limit of a few tens of nanometers can still remain.

  7. Direct Observation of Single DNA Structural Alterations at Low Forces with Surface-Enhanced Raman Scattering

    PubMed Central

    Rao, Satish; Raj, Saurabh; Cossins, Benjamin; Marro, Monica; Guallar, Victor; Petrov, Dmitri

    2013-01-01

    DNA experiences numerous mechanical events, necessitating single-molecule force spectroscopy techniques to provide insight into DNA mechanics as a whole system. Inherent Brownian motion limits current force spectroscopy methods from observing possible bond level structural changes. We combine optical trapping and surface-enhanced Raman scattering to establish a direct relationship between DNA’s extension and structure in the low force, entropic regime. A DNA molecule is trapped close to a surface-enhanced Raman scattering substrate to facilitate a detectable Raman signal. DNA Raman modes shift in response to applied force, indicating phosphodiester mechanical alterations. Molecular dynamic simulations confirm the local structural alterations and the Raman sensitive band identified experimentally. The combined Raman and force spectroscopy technique, to our knowledge, is a novel methodology that can be generalized to all single-molecule studies. PMID:23332068

  8. Using surface-enhanced Raman spectroscopy to probe for genetic markers on single-stranded DNA

    NASA Astrophysics Data System (ADS)

    Moody, Benjamin; Leotaud, John; McCarty, Gregory S.

    2010-03-01

    Methods capable of quickly and inexpensively collecting genetic information are of increasing importance. We report a method of using surface-enhanced Raman spectroscopy to probe single-stranded DNA for genetic markers. This unique approach is used to analyze unmodified genes of moderate length for genetic markers by hybridizing native test oligonucleotides into a surface-enhanced Raman complex, vastly increasing detection sensitivity as compared to traditional Raman spectroscopy. The Raman complex is formed by sandwiching the test DNA between 40-nm gold nanoparticles and a photolithographically defined gold surface. With this design, we are able to collect characteristic Raman spectra about the test DNA and to detect genetic markers such as single-nucleotide polymorphisms (SNPs) and polymorphic regions. Results show that strands containing one of three different types of polymorphism can be differentiated using statistically significant trends regarding Raman intensity.

  9. Gabor filter based fingerprint image enhancement

    NASA Astrophysics Data System (ADS)

    Wang, Jin-Xiang

    2013-03-01

    Fingerprint recognition technology has become the most reliable biometric technology due to its uniqueness and invariance, which has been most convenient and most reliable technique for personal authentication. The development of Automated Fingerprint Identification System is an urgent need for modern information security. Meanwhile, fingerprint preprocessing algorithm of fingerprint recognition technology has played an important part in Automatic Fingerprint Identification System. This article introduces the general steps in the fingerprint recognition technology, namely the image input, preprocessing, feature recognition, and fingerprint image enhancement. As the key to fingerprint identification technology, fingerprint image enhancement affects the accuracy of the system. It focuses on the characteristics of the fingerprint image, Gabor filters algorithm for fingerprint image enhancement, the theoretical basis of Gabor filters, and demonstration of the filter. The enhancement algorithm for fingerprint image is in the windows XP platform with matlab.65 as a development tool for the demonstration. The result shows that the Gabor filter is effective in fingerprint image enhancement technology.

  10. High-Tc/high-coupling relaxed PZT-based single crystal thin films

    NASA Astrophysics Data System (ADS)

    Wasa, K.; Matsushima, T.; Adachi, H.; Matsunaga, T.; Yanagitani, T.; Yamamoto, T.

    2015-03-01

    Pb(Zr,Ti)O3 (PZT)-based ferroelectric ceramics exhibit high piezoelectricity, however, their Curie temperature (Tc) values are not so high, i.e., Tc < 400 °C. PZT-based piezoelectric thin films with higher Tc would be beneficial for improved micro actuators, sensors, memories, and piezoelectric micro-electro mechanical systems. In-plane biaxial strained PZT thin films in a laminated composite structure are known to exhibit enhanced Tc; however, the thickness of PZT-based thin films is limited to below a critical thickness typically <50 nm. The Tc of relaxed PZT-based thin films with thicknesses greater than the critical thickness is the same as bulk Tc. However, a sort of relaxed PZT-based single-crystal thin films exhibit extraordinary high Tc, Tc = ˜600 °C. In addition, the films show extremely low dielectric constant, ɛ/ɛo ˜ 100 with high coupling factor, kt ˜ 0.7, and large remnant polarization, Pr ˜ 100 μC/cm2. These exotic properties would result from the single-domain/single-crystal structure. The enhanced Tc is possibly caused by the highly stable interface between the PZT-based thin films and substrates. Their ferroelectric performances are beyond those of conventional PZT. The high-Tc/high-coupling performances are demonstrated, and the possible mechanisms of the high Tc behavior in relaxed PZT-based single-crystal thin films are discussed.

  11. Single-shot and single-sensor high/super-resolution microwave imaging based on metasurface.

    PubMed

    Wang, Libo; Li, Lianlin; Li, Yunbo; Zhang, Hao Chi; Cui, Tie Jun

    2016-01-01

    Real-time high-resolution (including super-resolution) imaging with low-cost hardware is a long sought-after goal in various imaging applications. Here, we propose broadband single-shot and single-sensor high-/super-resolution imaging by using a spatio-temporal dispersive metasurface and an imaging reconstruction algorithm. The metasurface with spatio-temporal dispersive property ensures the feasibility of the single-shot and single-sensor imager for super- and high-resolution imaging, since it can convert efficiently the detailed spatial information of the probed object into one-dimensional time- or frequency-dependent signal acquired by a single sensor fixed in the far-field region. The imaging quality can be improved by applying a feature-enhanced reconstruction algorithm in post-processing, and the desired imaging resolution is related to the distance between the object and metasurface. When the object is placed in the vicinity of the metasurface, the super-resolution imaging can be realized. The proposed imaging methodology provides a unique means to perform real-time data acquisition, high-/super-resolution images without employing expensive hardware (e.g. mechanical scanner, antenna array, etc.). We expect that this methodology could make potential breakthroughs in the areas of microwave, terahertz, optical, and even ultrasound imaging.

  12. Single-shot and single-sensor high/super-resolution microwave imaging based on metasurface

    NASA Astrophysics Data System (ADS)

    Wang, Libo; Li, Lianlin; Li, Yunbo; Zhang, Hao Chi; Cui, Tie Jun

    2016-06-01

    Real-time high-resolution (including super-resolution) imaging with low-cost hardware is a long sought-after goal in various imaging applications. Here, we propose broadband single-shot and single-sensor high-/super-resolution imaging by using a spatio-temporal dispersive metasurface and an imaging reconstruction algorithm. The metasurface with spatio-temporal dispersive property ensures the feasibility of the single-shot and single-sensor imager for super- and high-resolution imaging, since it can convert efficiently the detailed spatial information of the probed object into one-dimensional time- or frequency-dependent signal acquired by a single sensor fixed in the far-field region. The imaging quality can be improved by applying a feature-enhanced reconstruction algorithm in post-processing, and the desired imaging resolution is related to the distance between the object and metasurface. When the object is placed in the vicinity of the metasurface, the super-resolution imaging can be realized. The proposed imaging methodology provides a unique means to perform real-time data acquisition, high-/super-resolution images without employing expensive hardware (e.g. mechanical scanner, antenna array, etc.). We expect that this methodology could make potential breakthroughs in the areas of microwave, terahertz, optical, and even ultrasound imaging.

  13. Single-shot and single-sensor high/super-resolution microwave imaging based on metasurface.

    PubMed

    Wang, Libo; Li, Lianlin; Li, Yunbo; Zhang, Hao Chi; Cui, Tie Jun

    2016-01-01

    Real-time high-resolution (including super-resolution) imaging with low-cost hardware is a long sought-after goal in various imaging applications. Here, we propose broadband single-shot and single-sensor high-/super-resolution imaging by using a spatio-temporal dispersive metasurface and an imaging reconstruction algorithm. The metasurface with spatio-temporal dispersive property ensures the feasibility of the single-shot and single-sensor imager for super- and high-resolution imaging, since it can convert efficiently the detailed spatial information of the probed object into one-dimensional time- or frequency-dependent signal acquired by a single sensor fixed in the far-field region. The imaging quality can be improved by applying a feature-enhanced reconstruction algorithm in post-processing, and the desired imaging resolution is related to the distance between the object and metasurface. When the object is placed in the vicinity of the metasurface, the super-resolution imaging can be realized. The proposed imaging methodology provides a unique means to perform real-time data acquisition, high-/super-resolution images without employing expensive hardware (e.g. mechanical scanner, antenna array, etc.). We expect that this methodology could make potential breakthroughs in the areas of microwave, terahertz, optical, and even ultrasound imaging. PMID:27246668

  14. Single-shot and single-sensor high/super-resolution microwave imaging based on metasurface

    PubMed Central

    Wang, Libo; Li, Lianlin; Li, Yunbo; Zhang, Hao Chi; Cui, Tie Jun

    2016-01-01

    Real-time high-resolution (including super-resolution) imaging with low-cost hardware is a long sought-after goal in various imaging applications. Here, we propose broadband single-shot and single-sensor high-/super-resolution imaging by using a spatio-temporal dispersive metasurface and an imaging reconstruction algorithm. The metasurface with spatio-temporal dispersive property ensures the feasibility of the single-shot and single-sensor imager for super- and high-resolution imaging, since it can convert efficiently the detailed spatial information of the probed object into one-dimensional time- or frequency-dependent signal acquired by a single sensor fixed in the far-field region. The imaging quality can be improved by applying a feature-enhanced reconstruction algorithm in post-processing, and the desired imaging resolution is related to the distance between the object and metasurface. When the object is placed in the vicinity of the metasurface, the super-resolution imaging can be realized. The proposed imaging methodology provides a unique means to perform real-time data acquisition, high-/super-resolution images without employing expensive hardware (e.g. mechanical scanner, antenna array, etc.). We expect that this methodology could make potential breakthroughs in the areas of microwave, terahertz, optical, and even ultrasound imaging. PMID:27246668

  15. An enhanced grid-based Bayesian array for target tracking

    NASA Astrophysics Data System (ADS)

    Sang, Qian; Lin, Zongli; Acton, Scott T.

    2013-02-01

    A grid-based Bayesian array (GBA) for robust visual tracking has recently been developed, which proposes a novel method of deterministic sample generation and sample weighting for position estimation. In particular, a target motion model is constructed, predicting target position in the next frame based on estimations in previous frames. Samples are generated by gridding within an ellipsoid centered at the prediction. For localization, radial edge detection is applied for each sample to determine if it is inside the target boundary. Sample weights are then assigned according to the number of the edge points detected around the sample and its distance from the predicted position. The position estimation is computed as the weighted sum of the sample set. In this paper, we enhance the capacity of the GBA tracker in accommodating the tracking of targets in video with erratic motion, by introducing adaptation in the motion model and iterative position estimation. The improved tracking performance over the original GBA tracker are demonstrated in tracking a single leukocyte in vivo and ground vehicle target observed from UAV videos, both undergoing abrupt changes in motion. The experimental results show that the enhanced GBA tracker outperforms the original by tracking more than 10% of the total number of frames, and increases the number of video sequences with all frames tracked by greater than 20%.

  16. Liquid level sensor based on fiber ring laser with single-mode-offset coreless-single-mode fiber structure

    NASA Astrophysics Data System (ADS)

    Wang, Zixiao; Tan, Zhongwei; Xing, Rui; Liang, Linjun; Qi, Yanhui; Jian, Shuisheng

    2016-10-01

    A novel reflective liquid level sensor based on single-mode-offset coreless-single-mode (SOCS) fiber structure is proposed and experimentally demonstrated. Theory analyses and experimental results indicate that offset fusion can remarkably enhance the sensitivity of sensor. Ending-reflecting structure makes the sensor compact and easy to deploy. Meanwhile, we propose a laser sensing system, and the SOCS structure is used as sensing head and laser filter simultaneously. Experimental results show that laser spectra with high optical signal-to-noise ratio (-30 dB) and narrow 3-dB bandwidth (<0.15 nm) are achieved. Various liquids with different indices are used for liquid level sensing, besides, the refractive index sensitivity is also investigated. In measurement range, the sensing system presents steady laser output.

  17. Enhancement of beam pulse controllability for a single-pulse formation system of a cyclotron

    SciTech Connect

    Kurashima, Satoshi Miyawaki, Nobumasa; Kashiwagi, Hirotsugu; Okumura, Susumu; Taguchi, Mitsumasa; Fukuda, Mitsuhiro

    2015-07-15

    The single-pulse formation technique using a beam chopping system consisting of two types of high-voltage beam kickers was improved to enhance the quality and intensity of the single-pulse beam with a pulse interval over 1 μs at the Japan Atomic Energy Agency cyclotron facility. A contamination rate of neighboring beam bunches in the single-pulse beam was reduced to less than 0.1%. Long-term purification of the single pulse beam was guaranteed by the well-controlled magnetic field stabilization system for the cyclotron magnet. Reduction of the multi-turn extraction number for suppressing the neighboring beam bunch contamination was achieved by restriction of a beam phase width and precise optimization of a particle acceleration phase. In addition, the single-pulse beam intensity was increased by a factor of two or more by a combination of two types of beam bunchers using sinusoidal and saw-tooth voltage waveforms. Provision of the high quality intense single-pulse beam contributed to improve the accuracy of experiments for investigation of scintillation light time-profile and for neutron energy measurement by a time-of-flight method.

  18. A single oncogenic enhancer rearrangement causes concomitant EVI1 and GATA2 deregulation in leukemia.

    PubMed

    Gröschel, Stefan; Sanders, Mathijs A; Hoogenboezem, Remco; de Wit, Elzo; Bouwman, Britta A M; Erpelinck, Claudia; van der Velden, Vincent H J; Havermans, Marije; Avellino, Roberto; van Lom, Kirsten; Rombouts, Elwin J; van Duin, Mark; Döhner, Konstanze; Beverloo, H Berna; Bradner, James E; Döhner, Hartmut; Löwenberg, Bob; Valk, Peter J M; Bindels, Eric M J; de Laat, Wouter; Delwel, Ruud

    2014-04-10

    Chromosomal rearrangements without gene fusions have been implicated in leukemogenesis by causing deregulation of proto-oncogenes via relocation of cryptic regulatory DNA elements. AML with inv(3)/t(3;3) is associated with aberrant expression of the stem-cell regulator EVI1. Applying functional genomics and genome-engineering, we demonstrate that both 3q rearrangements reposition a distal GATA2 enhancer to ectopically activate EVI1 and simultaneously confer GATA2 functional haploinsufficiency, previously identified as the cause of sporadic familial AML/MDS and MonoMac/Emberger syndromes. Genomic excision of the ectopic enhancer restored EVI1 silencing and led to growth inhibition and differentiation of AML cells, which could be replicated by pharmacologic BET inhibition. Our data show that structural rearrangements involving the chromosomal repositioning of a single enhancer can cause deregulation of two unrelated distal genes, with cancer as the outcome.

  19. Fluorescence enhancement of radix angelica dahurica by binding to single silver sphere

    NASA Astrophysics Data System (ADS)

    Wang, Qing-Ru; Shi, Qiang; Li, Shu-Hong; Wang, Wen-Jun

    2015-05-01

    We present a theoretical study of the influence of a single silver sphere on the fluorescence of radix angelica dahurica, which is a kind of traditional Chinese medicine. The enhancement factors of the excitation and the relaxation processes are deduced. The excitation can be enhanced more than 100 times at 315 nm. The enhancement factor of the emission can reach up to 9 at a center wavelength of 400 nm. Project supported by the National Natural Science Foundation of China (Grant Nos. 61405085 and 61275147), the Research Fund for the Doctoral Program of Liaocheng University, China, the Key Project of Science and Technology of Shandong Province of China (Grant No. 2010GGX10127), and the Shandong Province Natural Science Foundation of China (Grant Nos. ZR2013EML006 and ZR2012AL11).

  20. On the low-temperature growth mechanism of single walled carbon nanotubes in plasma enhanced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Shariat, M.; Shokri, B.; Neyts, E. C.

    2013-12-01

    Despite significant progress in single walled carbon nanotube (SWCNT) production by plasma enhanced chemical vapor deposition (PECVD), the growth mechanism in this method is not clearly understood. We employ reactive molecular dynamics simulations to investigate how plasma-based deposition allows growth at low temperature. We first investigate the SWCNT growth mechanism at low and high temperatures under conditions similar to thermal CVD and PECVD. We then show how ion bombardment during the nucleation stage increases the carbon solubility in the catalyst at low temperature. Finally, we demonstrate how moderate energy ions sputter amorphous carbon allowing for SWCNT growth at 500 K.

  1. Free-space to single-mode collection efficiency enhancement using photonic lanterns.

    PubMed

    Ozdur, Ibrahim; Toliver, Paul; Agarwal, Anjali; Woodward, T K

    2013-09-15

    We demonstrate single-mode collection efficiency enhancement for free space optical systems using a photonic lantern to collect scattered infrared light from diffuse objects at far- and near-field distances. A single-mode collection efficiency improvement of ∼8  dB is demonstrated in the near-field region relative to standard single-mode fiber. The insertion loss properties of the photonic lantern are also analyzed, and an additional insertion loss penalty is observed for near-field distances when the transmitted beam is collimated. The photonic lantern can be used for coherent detection systems such as light detection and ranging and free-space optical communication with improved collection efficiency and nearly perfect mode matching.

  2. Expressly Fabricated Molar Tube Bases: Enhanced Adhesion

    PubMed Central

    Phull, Tarun Singh; Rana, Tarun; Kumar, Varun

    2014-01-01

    Clinicians, Orthodontists and their patients’ parents often expect the best results in the shortest time span possible. Orthodontic bonding of molar tubes has been an acceptable risk in a modern era of refined biomaterials and instrumentation. Although many orthodontists still prefer banding to bonding, it is the failure rate of the tubes on molars which accounts to an impedance in molar bonding. One of the reasons for molar attachment failures is attributed to improper adaptation of the buccal tube base with or without increased thickness of composite. Merits of banding the second molars especially when these are the terminal teeth for anchorage have been overemphasized in the literature. The present article presents a simple and relatively less time consuming technique of preparing molar tubes to be bonded on tooth surfaces which may be quite difficult to isolate especially for bonding, for example, mandibular second molars. The increased surface area of the composite scaffold helps not only in enhanced bond strength but also serves to reduce the incidence of plaque accumulation given the dexterity of invitro preparation. The removal of the occlusal part of the molar tube scaffold helps in prevention of open / raised bite tendencies. The present innovation, therefore, is not merely serendipity but a structured technique to overcome a common dilemma for the clinical orthodontist. The present dictum of banding being superior to molar tube bonding may prove to be futile with trendsetting molar attachments. It is also an established fact that bonding proves to be a lesser expensive modality when compared to banding procedures. PMID:25121070

  3. Expressly fabricated molar tube bases: enhanced adhesion.

    PubMed

    Sharma, Tarun; Phull, Tarun Singh; Rana, Tarun; Kumar, Varun

    2014-06-01

    Clinicians, Orthodontists and their patients' parents often expect the best results in the shortest time span possible. Orthodontic bonding of molar tubes has been an acceptable risk in a modern era of refined biomaterials and instrumentation. Although many orthodontists still prefer banding to bonding, it is the failure rate of the tubes on molars which accounts to an impedance in molar bonding. One of the reasons for molar attachment failures is attributed to improper adaptation of the buccal tube base with or without increased thickness of composite. Merits of banding the second molars especially when these are the terminal teeth for anchorage have been overemphasized in the literature. The present article presents a simple and relatively less time consuming technique of preparing molar tubes to be bonded on tooth surfaces which may be quite difficult to isolate especially for bonding, for example, mandibular second molars. The increased surface area of the composite scaffold helps not only in enhanced bond strength but also serves to reduce the incidence of plaque accumulation given the dexterity of invitro preparation. The removal of the occlusal part of the molar tube scaffold helps in prevention of open / raised bite tendencies. The present innovation, therefore, is not merely serendipity but a structured technique to overcome a common dilemma for the clinical orthodontist. The present dictum of banding being superior to molar tube bonding may prove to be futile with trendsetting molar attachments. It is also an established fact that bonding proves to be a lesser expensive modality when compared to banding procedures. PMID:25121070

  4. Photoluminescence enhancement of aligned arrays of single-walled carbon nanotubes by polymer transfer

    NASA Astrophysics Data System (ADS)

    Schweiger, Manuel; Zakharko, Yuriy; Gannott, Florentina; Grimm, Stefan B.; Zaumseil, Jana

    2015-10-01

    The photoluminescence of as-grown, aligned single-walled carbon nanotubes (SWNTs) on quartz is strongly quenched and barely detectable. Here we show that transferring these SWNTs to another substrate such as clean quartz or glass increases their emission efficiency by up to two orders of magnitude. By statistical analysis of large nanotube arrays we show at what point of the transfer process the emission enhancement occurs and how it depends on the receiving substrate and the employed transfer polymer. We find that hydrophobic polystyrene (PS) as the transfer polymer results in higher photoluminescence enhancement than the more hydrophilic poly(methyl methacrylate) (PMMA). Possible mechanisms for this enhancement such as strain relief, disruption of the strong interaction of SWNTs with the substrate and localized emissive states are discussed.The photoluminescence of as-grown, aligned single-walled carbon nanotubes (SWNTs) on quartz is strongly quenched and barely detectable. Here we show that transferring these SWNTs to another substrate such as clean quartz or glass increases their emission efficiency by up to two orders of magnitude. By statistical analysis of large nanotube arrays we show at what point of the transfer process the emission enhancement occurs and how it depends on the receiving substrate and the employed transfer polymer. We find that hydrophobic polystyrene (PS) as the transfer polymer results in higher photoluminescence enhancement than the more hydrophilic poly(methyl methacrylate) (PMMA). Possible mechanisms for this enhancement such as strain relief, disruption of the strong interaction of SWNTs with the substrate and localized emissive states are discussed. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr05163k

  5. Cisplatin enhances the formation of DNA single- and double-strand breaks by hydrated electrons and hydroxyl radicals.

    PubMed

    Rezaee, Mohammad; Sanche, Léon; Hunting, Darel J

    2013-03-01

    The synergistic interaction of cisplatin with ionizing radiation is the clinical rationale for the treatment of several cancers including head and neck, cervical and lung cancer. The underlying molecular mechanism of the synergy has not yet been identified, although both DNA damage and repair processes are likely involved. Here, we investigate the indirect effect of γ rays on strand break formation in a supercoiled plasmid DNA (pGEM-3Zf-) covalently modified by cisplatin. The yields of single- and double-strand breaks were determined by irradiation of DNA and cisplatin/DNA samples with (60)Co γ rays under four different scavenging conditions to examine the involvement of hydrated electrons and hydroxyl radicals in inducing the DNA damage. At 5 mM tris in an N2 atmosphere, the presence of an average of two cisplatins per plasmid increased the yields of single- and double-strand breaks by factors of 1.9 and 2.2, respectively, relative to the irradiated unmodified DNA samples. Given that each plasmid of 3,200 base pairs contained an average of two cisplatins, this represents an increase in radiosensitivity of 3,200-fold on a per base pair basis. When hydrated electrons were scavenged by saturating the samples with N2O, these enhancement factors decreased to 1.5 and 1.2, respectively, for single- and double-strand breaks. When hydroxyl radicals were scavenged using 200 mM tris, the respective enhancement factors were 1.2 and 1.6 for single- and double-strand breaks, respectively. Furthermore, no enhancement in DNA damage by cisplatin was observed after scavenging both hydroxyl radicals and hydrated electrons. These findings show that hydrated electrons can induce both single- and double-strand breaks in the platinated DNA, but not in unmodified DNA. In addition, cisplatin modification is clearly an extremely efficient means of increasing the formation of both single- and double-strand breaks by the hydrated electrons and hydroxyl radicals created by ionizing

  6. Enhanced genetic analysis of single human bioparticles recovered by simplified micromanipulation from forensic 'touch DNA' evidence.

    PubMed

    Farash, Katherine; Hanson, Erin K; Ballantyne, Jack

    2015-03-09

    DNA profiles can be obtained from 'touch DNA' evidence, which comprises microscopic traces of human biological material. Current methods for the recovery of trace DNA employ cotton swabs or adhesive tape to sample an area of interest. However, such a 'blind-swabbing' approach will co-sample cellular material from the different individuals, even if the individuals' cells are located in geographically distinct locations on the item. Thus, some of the DNA mixtures encountered in touch DNA samples are artificially created by the swabbing itself. In some instances, a victim's DNA may be found in significant excess thus masking any potential perpetrator's DNA. In order to circumvent the challenges with standard recovery and analysis methods, we have developed a lower cost, 'smart analysis' method that results in enhanced genetic analysis of touch DNA evidence. We describe an optimized and efficient micromanipulation recovery strategy for the collection of bio-particles present in touch DNA samples, as well as an enhanced amplification strategy involving a one-step 5 µl microvolume lysis/STR amplification to permit the recovery of STR profiles from the bio-particle donor(s). The use of individual or few (i.e., "clumps") bioparticles results in the ability to obtain single source profiles. These procedures represent alternative enhanced techniques for the isolation and analysis of single bioparticles from forensic touch DNA evidence. While not necessary in every forensic investigation, the method could be highly beneficial for the recovery of a single source perpetrator DNA profile in cases involving physical assault (e.g., strangulation) that may not be possible using standard analysis techniques. Additionally, the strategies developed here offer an opportunity to obtain genetic information at the single cell level from a variety of other non-forensic trace biological material.

  7. Heat transfer enhancement due to a longitudinal vortex produced by a single winglet in a pipe

    SciTech Connect

    Oyakawa, Kenyu; Senaha, Izuru; Ishikawa, Shuji; Hokama, Mashashige

    1999-07-01

    Longitudinal vortices were artificially generated by a single winglet vortex generator in a pipe. The purpose of this study is to analyze the motion of longitudinal vortices and their effects on heat transfer enhancement. The flow pattern was visualized by means of both fluorescein and rhodamine B as traces in a water flow. The main vortex was moved spirally along the circumference and the behavior of the other vortices was observed. Streamwise and circumferential heat transfer coefficients on the wall, wall static pressure, and velocity distribution in an overall cross section were also measured for the air flow in a range of Reynolds numbers from 18,800 to 62,400. The distributions of the streamwise heat transfer coefficient had a periodic pattern, and the peaks in the distribution were circumferentially moved due to the spiral motion of the main vortex. Lastly, the relationships between the iso-velocity distribution, wall static pressure, and heat transfer characteristics was shown. In the process of forming the vortex behind the winglet vortex generator, behaviors of both the main vortex and the corner vortex were observed as streak lines. The vortex being raised along the end of the winglet, and the vortex ring being rolled up to the main vortex were newly observed. Both patterns of the streamwise velocity on a cross-section and the static pressure on the wall show good correspondences to phenomena of the main vortex spirally flowing downstream. The increased ratio of the heat transfer is similar to that of the friction factor based on the shear stress on the wall surface of the pipe. The quantitative analogy between the heat transfer and the shear stress is confirmed except for some regions, where the effects of the down-wash or blow-away of the secondary flows is caused due to the main vortex.

  8. Growth kinetics of low temperature single-wall and few walled carbon nanotubes grown by plasma enhanced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Gohier, A.; Minea, T. M.; Djouadi, M. A.; Jiménez, J.; Granier, A.

    2007-03-01

    Single-wall, double walled or few walled nanotubes (FWNT) are grown by electron cyclotron resonance plasma enhanced chemical vapor deposition (ECR-PECVD) at temperature as low as 600 °C. Most of these structures are isolated and self-oriented perpendicular to the substrate. The growth mechanism observed for single-wall and few walled (less than seven walls) nanotubes is the “base-growth” mode. Their grow kinetics is investigated regarding two parameters namely the growth time and the synthesis temperature. It is shown that nucleation and growth rate is correlated with the number of walls into FWNT. It also provides an evidence of a critical temperature for FWNT synthesis.

  9. Trityl-based EPR probe with enhanced sensitivity to oxygen

    PubMed Central

    Bobko, Andrey A.; Dhimitruka, Ilirian; Eubank, Timothy D.; Marsh, Clay B.; Zweier, Jay L.; Khramtsov, Valery V.

    2009-01-01

    An asymmetric derivative of triarylmethyl radical, TAM-H, containing one aldehyde and two carboxyl groups was synthesized. The electron paramagnetic resonance, EPR, spectrum of TAM-H is characterized by a doublet of narrow lines with linewidth of 105 mG in anoxic conditions and hyperfine interaction constant 245 mG. The partial overlap of the components of the doublet results in enhanced sensitivity of the spectral amplitudes ratio to oxygen compared with oxygen-induced linewidth broadening of a single line. Application of the TAM-H probe allows for EPR measurements in an extended range of oxygen pressures from atmospheric to 1 mmHg whereas the EPR spectrum linewidth of the popular TAM-based oxygen sensor, Oxo63, is practically insensitive to oxygen partial pressures below 20 mmHg. Enhanced sensitivity of TAM-H probe relative to Oxo63 was demonstrated in detection of oxygen consumption by Met-1 cancer cells. The TAM-H probe allowed prolonged measurements of oxygen depletion during the hypoxia stage and down to true anoxia (≤ 1.5 mmHg). PMID:19523513

  10. Contrast Enhancement Algorithm Based on Gap Adjustment for Histogram Equalization

    PubMed Central

    Chiu, Chung-Cheng; Ting, Chih-Chung

    2016-01-01

    Image enhancement methods have been widely used to improve the visual effects of images. Owing to its simplicity and effectiveness histogram equalization (HE) is one of the methods used for enhancing image contrast. However, HE may result in over-enhancement and feature loss problems that lead to unnatural look and loss of details in the processed images. Researchers have proposed various HE-based methods to solve the over-enhancement problem; however, they have largely ignored the feature loss problem. Therefore, a contrast enhancement algorithm based on gap adjustment for histogram equalization (CegaHE) is proposed. It refers to a visual contrast enhancement algorithm based on histogram equalization (VCEA), which generates visually pleasing enhanced images, and improves the enhancement effects of VCEA. CegaHE adjusts the gaps between two gray values based on the adjustment equation, which takes the properties of human visual perception into consideration, to solve the over-enhancement problem. Besides, it also alleviates the feature loss problem and further enhances the textures in the dark regions of the images to improve the quality of the processed images for human visual perception. Experimental results demonstrate that CegaHE is a reliable method for contrast enhancement and that it significantly outperforms VCEA and other methods. PMID:27338412

  11. Vertically-Aligned Single-Crystal Nanocone Arrays: Controlled Fabrication and Enhanced Field Emission.

    PubMed

    Duan, Jing Lai; Lei, Dang Yuan; Chen, Fei; Lau, Shu Ping; Milne, William I; Toimil-Molares, M E; Trautmann, Christina; Liu, Jie

    2016-01-13

    Metal nanostructures with conical shape, vertical alignment, large ratio of cone height and curvature radius at the apex, controlled cone angle, and single-crystal structure are ideal candidates for enhancing field electron-emission efficiency with additional merits, such as good mechanical and thermal stability. However, fabrication of such nanostructures possessing all these features is challenging. Here, we report on the controlled fabrication of large scale, vertically aligned, and mechanically self-supported single-crystal Cu nanocones with controlled cone angle and enhanced field emission. The Cu nanocones were fabricated by ion-track templates in combination with electrochemical deposition. Their cone angle is controlled in the range from 0.3° to 6.2° by asymmetrically selective etching of the ion tracks and the minimum tip curvature diameter reaches down to 6 nm. The field emission measurements show that the turn-on electric field of the Cu nanocone field emitters can be as low as 1.9 V/μm at current density of 10 μA/cm(2) (a record low value for Cu nanostructures, to the best of our knowledge). The maximum field enhancement factor we measured was as large as 6068, indicating that the Cu nanocones are promising candidates for field emission applications.

  12. Engineered Hematite Mesoporous Single Crystals Drive Drastic Enhancement in Solar Water Splitting.

    PubMed

    Wang, Chong Wu; Yang, Shuang; Fang, Wen Qi; Liu, Porun; Zhao, Huijun; Yang, Hua Gui

    2016-01-13

    Mesoporous single crystals (MSCs) rendering highly accessible surface area and long-range electron conductivity are extremely significant in many fields, including catalyst, solar fuel, and electrical energy storage technologies. Hematite semiconductor, whose performance has been crucially limited by its pristine poor charge separation efficiency in solar water splitting, should benefit from this strategy. Despite successful synthesis of many metal oxide MSCs, the fabrication of hematite MSCs remains to be a great challenge due to its quite slow hydrolysis rate in water. Herein, for the first time, we have developed a synthetic strategy to prepare hematite MSCs and systematically investigated their growth mechanism. The electrode fabricated with these crystals is able to achieve a photocurrent density of 0.61 mA/cm(2) at 1.23 V vs RHE under AM 1.5G simulated sunlight, which is 20 times higher than that of electrodes made of solid single crystals. The enhancement is ascribed to the superior light absorption and enhanced charges separation. Our results demonstrate the advantage of incorporation of nanopores into the large-sized hematite single crystals and provide a valuable insight for the development of high performance photoelectrodes in PEC application. PMID:26654272

  13. Engineered Hematite Mesoporous Single Crystals Drive Drastic Enhancement in Solar Water Splitting.

    PubMed

    Wang, Chong Wu; Yang, Shuang; Fang, Wen Qi; Liu, Porun; Zhao, Huijun; Yang, Hua Gui

    2016-01-13

    Mesoporous single crystals (MSCs) rendering highly accessible surface area and long-range electron conductivity are extremely significant in many fields, including catalyst, solar fuel, and electrical energy storage technologies. Hematite semiconductor, whose performance has been crucially limited by its pristine poor charge separation efficiency in solar water splitting, should benefit from this strategy. Despite successful synthesis of many metal oxide MSCs, the fabrication of hematite MSCs remains to be a great challenge due to its quite slow hydrolysis rate in water. Herein, for the first time, we have developed a synthetic strategy to prepare hematite MSCs and systematically investigated their growth mechanism. The electrode fabricated with these crystals is able to achieve a photocurrent density of 0.61 mA/cm(2) at 1.23 V vs RHE under AM 1.5G simulated sunlight, which is 20 times higher than that of electrodes made of solid single crystals. The enhancement is ascribed to the superior light absorption and enhanced charges separation. Our results demonstrate the advantage of incorporation of nanopores into the large-sized hematite single crystals and provide a valuable insight for the development of high performance photoelectrodes in PEC application.

  14. Framework for single input single output nanonetwork-based realistic molecular communication.

    PubMed

    Abd El-Atty, Saied M; Gharsseldien, Zakaria M; Lizos, Konstantinos A

    2015-12-01

    Mobile ad hoc molecular nanonetwork (MAMNET) is a new paradigm for the realisation of future nanonetworks. In MAMNET, transmission of nanoscale information from nanomachine to infostation is based on collision and adhesion. In this study, the authors develop a realistic framework for encompassing the electronic structure of the neurotransmitter in the process of transmitting nanoscale information at a single input single output nanonetwork. Nanonetwork performance is evaluated in terms of average packet delay, throughput and incurred traffic rate. Numerical results demonstrate the influence of the neurotransmitter's electronic structure over the performance of nanonetworks. PMID:26647808

  15. Framework for single input single output nanonetwork-based realistic molecular communication.

    PubMed

    Abd El-Atty, Saied M; Gharsseldien, Zakaria M; Lizos, Konstantinos A

    2015-12-01

    Mobile ad hoc molecular nanonetwork (MAMNET) is a new paradigm for the realisation of future nanonetworks. In MAMNET, transmission of nanoscale information from nanomachine to infostation is based on collision and adhesion. In this study, the authors develop a realistic framework for encompassing the electronic structure of the neurotransmitter in the process of transmitting nanoscale information at a single input single output nanonetwork. Nanonetwork performance is evaluated in terms of average packet delay, throughput and incurred traffic rate. Numerical results demonstrate the influence of the neurotransmitter's electronic structure over the performance of nanonetworks.

  16. Wavelet-Based Speech Enhancement Using Time-Adapted Noise Estimation

    NASA Astrophysics Data System (ADS)

    Lei, Sheau-Fang; Tung, Ying-Kai

    Spectral subtraction is commonly used for speech enhancement in a single channel system because of the simplicity of its implementation. However, this algorithm introduces perceptually musical noise while suppressing the background noise. We propose a wavelet-based approach in this paper for suppressing the background noise for speech enhancement in a single channel system. The wavelet packet transform, which emulates the human auditory system, is used to decompose the noisy signal into critical bands. Wavelet thresholding is then temporally adjusted with the noise power by time-adapted noise estimation. The proposed algorithm can efficiently suppress the noise while reducing speech distortion. Experimental results, including several objective measurements, show that the proposed wavelet-based algorithm outperforms spectral subtraction and other wavelet-based denoising approaches for speech enhancement for nonstationary noise environments.

  17. Fluorescent Biosensors Based on Single-Molecule Counting.

    PubMed

    Ma, Fei; Li, Ying; Tang, Bo; Zhang, Chun-Yang

    2016-09-20

    Biosensors for highly sensitive, selective, and rapid quantification of specific biomolecules make great contributions to biomedical research, especially molecular diagnostics. However, conventional methods for biomolecular assays often suffer from insufficient sensitivity and poor specificity. In some case (e.g., early disease diagnostics), the concentration of target biomolecules is too low to be detected by these routine approaches, and cumbersome procedures are needed to improve the detection sensitivity. Therefore, there is an urgent need for rapid and ultrasensitive analytical tools. In this respect, single-molecule fluorescence approaches may well satisfy the requirement and hold promising potential for the development of ultrasensitive biosensors. Encouragingly, owing to the advances in single-molecule microscopy and spectroscopy over past decades, the detection of single fluorescent molecule comes true, greatly boosting the development of highly sensitive biosensors. By in vitro/in vivo labeling of target biomolecules with proper fluorescent tags, the quantification of certain biomolecule at the single-molecule level is achieved. In comparison with conventional ensemble measurements, single-molecule detection-based analytical methods possess the advantages of ultrahigh sensitivity, good selectivity, rapid analysis time, and low sample consumption. Consequently, single-molecule detection may be potentially employed as an ideal analytical approach to quantify low-abundant biomolecules with rapidity and simplicity. In this Account, we will summarize our efforts for developing a series of ultrasensitive biosensors based on single-molecule counting. Single-molecule counting is a member of single-molecule detection technologies and may be used as a very simple and ultrasensitive method to quantify target molecules by simply counting the individual fluorescent bursts. In the fluorescent sensors, the signals of target biomolecules may be translated to the

  18. Fluorescent Biosensors Based on Single-Molecule Counting.

    PubMed

    Ma, Fei; Li, Ying; Tang, Bo; Zhang, Chun-Yang

    2016-09-20

    Biosensors for highly sensitive, selective, and rapid quantification of specific biomolecules make great contributions to biomedical research, especially molecular diagnostics. However, conventional methods for biomolecular assays often suffer from insufficient sensitivity and poor specificity. In some case (e.g., early disease diagnostics), the concentration of target biomolecules is too low to be detected by these routine approaches, and cumbersome procedures are needed to improve the detection sensitivity. Therefore, there is an urgent need for rapid and ultrasensitive analytical tools. In this respect, single-molecule fluorescence approaches may well satisfy the requirement and hold promising potential for the development of ultrasensitive biosensors. Encouragingly, owing to the advances in single-molecule microscopy and spectroscopy over past decades, the detection of single fluorescent molecule comes true, greatly boosting the development of highly sensitive biosensors. By in vitro/in vivo labeling of target biomolecules with proper fluorescent tags, the quantification of certain biomolecule at the single-molecule level is achieved. In comparison with conventional ensemble measurements, single-molecule detection-based analytical methods possess the advantages of ultrahigh sensitivity, good selectivity, rapid analysis time, and low sample consumption. Consequently, single-molecule detection may be potentially employed as an ideal analytical approach to quantify low-abundant biomolecules with rapidity and simplicity. In this Account, we will summarize our efforts for developing a series of ultrasensitive biosensors based on single-molecule counting. Single-molecule counting is a member of single-molecule detection technologies and may be used as a very simple and ultrasensitive method to quantify target molecules by simply counting the individual fluorescent bursts. In the fluorescent sensors, the signals of target biomolecules may be translated to the

  19. Enhanced Student Learning with Problem Based Learning

    ERIC Educational Resources Information Center

    Hollenbeck, James

    2008-01-01

    Science educators define a learning environment in which the problem drives the learning as problem based learning (PBL). Problem based learning can be a learning methodology/process or a curriculum based on its application by the teacher. This paper discusses the basic premise of Problem base learning and successful applications of such learning.…

  20. Fast Purcell-enhanced single photon source in 1,550-nm telecom band from a resonant quantum dot-cavity coupling

    PubMed Central

    Birowosuto, Muhammad Danang; Sumikura, Hisashi; Matsuo, Shinji; Taniyama, Hideaki; van Veldhoven, Peter J.; Nötzel, Richard; Notomi, Masaya

    2012-01-01

    High-bit-rate nanocavity-based single photon sources in the 1,550-nm telecom band are challenges facing the development of fibre-based long-haul quantum communication networks. Here we report a very fast single photon source in the 1,550-nm telecom band, which is achieved by a large Purcell enhancement that results from the coupling of a single InAs quantum dot and an InP photonic crystal nanocavity. At a resonance, the spontaneous emission rate was enhanced by a factor of 5 resulting a record fast emission lifetime of 0.2 ns at 1,550 nm. We also demonstrate that this emission exhibits an enhanced anti-bunching dip. This is the first realization of nanocavity-enhanced single photon emitters in the 1,550-nm telecom band. This coupled quantum dot cavity system in the telecom band thus provides a bright high-bit-rate non-classical single photon source that offers appealing novel opportunities for the development of a long-haul quantum telecommunication system via optical fibres. PMID:22432053

  1. Oxygen-enhanced thermionic emission pattern of hemispherical single-crystal LaB6

    NASA Astrophysics Data System (ADS)

    Shimizu, R.; Onoda, H.; Hashimoto, H.; Hagiwara, H.

    1984-03-01

    With the application of Martin's experimental arrangement for direct observation of thermionic emission patterns from a hemispherical single-crystal LaB6 cathode, it has been determined that oxygen-enhanced thermionic emission does occur for the (210) plane at the rather low partial pressure of oxygen, i.e., in the 10-9-Torr region, at sample temperatures of 1050 °C. For further quantitative assessment, work-function measurements by Richardson plots were done for different crystal planes of clean surface by attaching a photomultiplier. The result clearly shows that the values of the work function increases in order from (100), (210), (110), and (111). The measurements were also extended to the oxygen-enhanced surface of the (210) plane and it was found that the results follow, phenomenologically, the Richardson plot as well.

  2. Communication: Multiple atomistic force fields in a single enhanced sampling simulation

    SciTech Connect

    Hoang Viet, Man; Derreumaux, Philippe; Nguyen, Phuong H.

    2015-07-14

    The main concerns of biomolecular dynamics simulations are the convergence of the conformational sampling and the dependence of the results on the force fields. While the first issue can be addressed by employing enhanced sampling techniques such as simulated tempering or replica exchange molecular dynamics, repeating these simulations with different force fields is very time consuming. Here, we propose an automatic method that includes different force fields into a single advanced sampling simulation. Conformational sampling using three all-atom force fields is enhanced by simulated tempering and by formulating the weight parameters of the simulated tempering method in terms of the energy fluctuations, the system is able to perform random walk in both temperature and force field spaces. The method is first demonstrated on a 1D system and then validated by the folding of the 10-residue chignolin peptide in explicit water.

  3. Communication: Multiple atomistic force fields in a single enhanced sampling simulation.

    PubMed

    Hoang Viet, Man; Derreumaux, Philippe; Nguyen, Phuong H

    2015-07-14

    The main concerns of biomolecular dynamics simulations are the convergence of the conformational sampling and the dependence of the results on the force fields. While the first issue can be addressed by employing enhanced sampling techniques such as simulated tempering or replica exchange molecular dynamics, repeating these simulations with different force fields is very time consuming. Here, we propose an automatic method that includes different force fields into a single advanced sampling simulation. Conformational sampling using three all-atom force fields is enhanced by simulated tempering and by formulating the weight parameters of the simulated tempering method in terms of the energy fluctuations, the system is able to perform random walk in both temperature and force field spaces. The method is first demonstrated on a 1D system and then validated by the folding of the 10-residue chignolin peptide in explicit water.

  4. Depth enhancement in spectral domain optical coherence tomography using bidirectional imaging modality with a single spectrometer

    NASA Astrophysics Data System (ADS)

    Ravichandran, Naresh Kumar; Wijesinghe, Ruchire Eranga; Shirazi, Muhammad Faizan; Park, Kibeom; Jeon, Mansik; Jung, Woonggyu; Kim, Jeehyun

    2016-07-01

    A method for depth enhancement is presented using a bidirectional imaging modality for spectral domain optical coherence tomography (SD-OCT). Two precisely aligned sample arms along with two reference arms were utilized in the optical configuration to scan the samples. Using exemplary images of the optical resolution target, Scotch tape, a silicon sheet with two needles, and a leaf, we demonstrated how the developed bidirectional SD-OCT imaging method increases the ability to characterize depth-enhanced images. The results of the developed system were validated by comparing the images with the standard OCT configuration (single-sample arm setup). Given the advantages of higher resolution and the ability to visualize deep morphological structures, this method can be utilized to increase the depth dependent fall-off in samples with limited thickness. Thus, the proposed bidirectional imaging modality is apt for cross-sectional imaging of entire samples, which has the potential capability to improve the diagnostic ability.

  5. Progress of the Enhanced Hanford Single Shell Tank (SST) Integrity Project

    SciTech Connect

    Venetz, Theodore J.; Washenfelder, Dennis J.; Boomer, Kayle D.; Johnson, Jeremy M.; Castleberry, Jim L.

    2015-01-07

    To improve the understanding of the single-shell tanks (SSTs) integrity, Washington River Protection Solutions, LLC (WRPS), the USDOE Hanford Site tank contractor, developed an enhanced Single-Shell Tank Integrity Project (SSTIP) in 2009. An expert panel on SST integrity, consisting of various subject matters experts in industry and academia, was created to provide recommendations supporting the development of the project. This panel developed 33 recommendations in four main areas of interest: structural integrity, liner degradation, leak integrity and prevention, and mitigation of contamination migration. In late 2010, seventeen of these recommendations were used to develop the basis for the M-45-10-1 Change Package for the Hanford Federal Agreement and Compliance Order, which is also known as the Tri-Party Agreement.

  6. Single-tube on-beam quartz-enhanced photoacoustic spectroscopy.

    PubMed

    Zheng, Huadan; Dong, Lei; Sampaolo, Angelo; Wu, Hongpeng; Patimisco, Pietro; Yin, Xukun; Ma, Weiguang; Zhang, Lei; Yin, Wangbao; Spagnolo, Vincenzo; Jia, Suotang; Tittel, Frank K

    2016-03-01

    Quartz-enhanced photoacoustic spectroscopy (QEPAS) with a single-tube acoustic microresonator (AmR) inserted between the prongs of a custom quartz tuning fork (QTF) was developed, investigated, and optimized experimentally. Due to the high acoustic coupling efficiency between the AmR and the QTF, the single-tube on-beam QEPAS spectrophone configuration improves the detection sensitivity by 2 orders of magnitude compared to a bare QTF. This approach significantly reduces the spectrophone size with respect to the traditional on-beam spectrophone configuration, thereby facilitating the laser beam alignment. A 1σ normalized noise equivalent absorption coefficient of 1.21×10(-8) cm(-1)·W/√Hz was obtained for dry CO2 detection at normal atmospheric pressure. PMID:26974095

  7. Microfluidic device for continuous single cells analysis via Raman spectroscopy enhanced by integrated plasmonic nanodimers.

    PubMed

    Perozziello, Gerardo; Candeloro, Patrizio; De Grazia, Antonio; Esposito, Francesco; Allione, Marco; Coluccio, Maria Laura; Tallerico, Rossana; Valpapuram, Immanuel; Tirinato, Luca; Das, Gobind; Giugni, Andrea; Torre, Bruno; Veltri, Pierangelo; Kruhne, Ulrich; Della Valle, Giuseppe; Di Fabrizio, Enzo

    2016-01-25

    In this work a Raman flow cytometer is presented. It consists of a microfluidic device that takes advantages of the basic principles of Raman spectroscopy and flow cytometry. The microfluidic device integrates calibrated microfluidic channels- where the cells can flow one-by-one -, allowing single cell Raman analysis. The microfluidic channel integrates plasmonic nanodimers in a fluidic trapping region. In this way it is possible to perform Enhanced Raman Spectroscopy on single cell. These allow a label-free analysis, providing information about the biochemical content of membrane and cytoplasm of the each cell. Experiments are performed on red blood cells (RBCs), peripheral blood lymphocytes (PBLs) and myelogenous leukemia tumor cells (K562).

  8. High electrical conductance enhancement in Au-nanoparticle decorated sparse single-wall carbon nanotube networks.

    PubMed

    McAndrew, Calum F; Baxendale, Mark

    2013-08-01

    We report high electrical conductance enhancement in sparse single-walled carbon nanotube networks by decoration with Au nanoparticles. The optimized hybrid network exhibited a sheet resistance of 650 Ω sq(-1), 1/1500 of the resistance of the host undecorated network, with a negligible optical transmission penalty (>90% transmittance at 550 nm wavelength). The electrical transport at room temperature in the host and decorated networks was dominated by two-dimensional variable range hopping. The high conductance enhancement was due to positive charge transfer from the decorating Au nanoparticles in intimate contact with the host network causing a Fermi energy shift into the high density of states at a van Hove singularity and enhanced electron delocalization relative to the host network which beneficially modifies the hopping parameters in such a way that the network behaves as an integral whole. The effect is most pronounced when the nanoparticle diameter is comparable to the electron mean free path in the bulk material at room temperature and there is minimum nanoparticle agglomeration. For higher than optimal values of nanoparticle coverage or nanoparticle diameter, the conductance enhancement is countered by metallic inclusions in the current pathways that are of higher resistance than the variable range hopping-controlled elements.

  9. Single base mismatch detection by microsecond voltage pulses.

    PubMed

    Fixe, F; Chu, V; Prazeres, D M F; Conde, J P

    2005-12-15

    A single square voltage pulse applied to metal electrodes underneath a silicon dioxide film upon which DNA probes are immobilized allows the discrimination of DNA targets with a single base mismatch during hybridization. Pulse duration, magnitude and slew rate of the voltage pulse are all key factors controlling the rates of electric field assisted hybridization. Although pulses with 1 V, lasting less than 1 ms and with a rise/fall times of 4.5 ns led to maximum hybridization of fully complementary strands, lack of stringency did not allow the discrimination of single base mismatches. However, by choosing pulse conditions that are slightly off the optimum, the selectivity for discriminating single base mismatches could be improved up to a factor approximately 5 when the mismatch was in the middle of the strand and up to approximately 1.5 when the mismatch was on the 5'-end and. These results demonstrate that hybridization with the appropriate electric field pulse provides a new, site-specific, approach to the discrimination of single nucleotide polymorphisms in the sub-millisecond time scale, for addressable DNA microarrays. PMID:16257657

  10. Enhanced thermoelectric power of single-wall carbon nanotube film blended with ionic liquid

    NASA Astrophysics Data System (ADS)

    Horike, Shohei; Misaki, Masahiro; Koshiba, Yasuko; Saito, Takeshi; Ishida, Kenji

    2016-03-01

    We have investigated the thermoelectric power of single-wall carbon nanotubes (SWCNTs) with an ionic liquid (IL). The SWCNT/IL films showed simultaneous increase in electrical conductivity and the Seebeck coefficient compared with the pristine SWCNT. No thermoelectric power was observed for the IL. The X-ray diffraction pattern and impedance diagram showed a unique behavior with the concentration of IL, which implies that the interaction between the SWCNTs and IL enhances the thermoelectric power of the SWCNTs. As a result of the simultaneous increase in these parameters, the power factor exhibited a 10-fold increase.

  11. Cavity-enhanced magnetooptical observation of magnetization reversal in individual single-domain nanomagnets.

    PubMed

    Qureshi, Naser; Wang, Suqin; Lowther, Mark A; Hawkins, Aaron R; Kwon, Sunghoon; Liddle, Alexander; Bokor, Jeffrey; Schmidt, Holger

    2005-07-01

    Optical studies of nanoscale magnets promise access to ultrafast magnetization dynamics but are challenging because of limited spatial resolution. We demonstrate that cavity enhancement of the magnetooptical Kerr effect increases the sensitivity in nanomagnetooptics significantly. Magnetization switching in individual single-domain magnets in both far-field and near-field Kerr microscopy is observed, and scaling laws are determined. Near-field signals remain nearly constant with reduced magnet diameter, indicating favorable scaling of near-field magnetooptics into the deep nanometer range. PMID:16178249

  12. Enhanced light coupling in sub-wavelength single-mode silicon on insulator waveguides.

    PubMed

    Pang, C; Gesuele, F; Bruyant, A; Blaize, S; Lérondel, G; Royer, P

    2009-04-27

    We report on NIR efficient end-coupling in single-mode silicon on insulator waveguides. Efficient coupling has been achieved using Polymer-Tipped Optical Fibers (PTOF) of adaptable radius of curvature (ROC). When compared with commercial micro lenses, systematic studies as a function of PTOF ROC, lead for subwavelength PTOF to a coupling factor enhancement as high as 2.5. This experimental behavior is clearly corroborated by radial FDTD simulations and an absolute coupling efficiency of about 50% is also estimated.

  13. Enhancement of Rydberg-mediated single-photon nonlinearities by electrically tuned Förster resonances

    NASA Astrophysics Data System (ADS)

    Gorniaczyk, H.; Tresp, C.; Bienias, P.; Paris-Mandoki, A.; Li, W.; Mirgorodskiy, I.; Büchler, H. P.; Lesanovsky, I.; Hofferberth, S.

    2016-08-01

    Mapping the strong interaction between Rydberg atoms onto single photons via electromagnetically induced transparency enables manipulation of light at the single-photon level and few-photon devices such as all-optical switches and transistors operated by individual photons. Here we demonstrate experimentally that Stark-tuned Förster resonances can substantially increase this effective interaction between individual photons. This technique boosts the gain of a single-photon transistor to over 100, enhances the non-destructive detection of single Rydberg atoms to a fidelity beyond 0.8, and enables high-precision spectroscopy on Rydberg pair states. On top, we achieve a gain larger than 2 with gate photon read-out after the transistor operation. Theory models for Rydberg polariton propagation on Förster resonance and for the projection of the stored spin-wave yield excellent agreement to our data and successfully identify the main decoherence mechanism of the Rydberg transistor, paving the way towards photonic quantum gates.

  14. Enhancement of Rydberg-mediated single-photon nonlinearities by electrically tuned Förster resonances

    PubMed Central

    Gorniaczyk, H.; Tresp, C.; Bienias, P.; Paris-Mandoki, A.; Li, W.; Mirgorodskiy, I.; Büchler, H. P.; Lesanovsky, I.; Hofferberth, S.

    2016-01-01

    Mapping the strong interaction between Rydberg atoms onto single photons via electromagnetically induced transparency enables manipulation of light at the single-photon level and few-photon devices such as all-optical switches and transistors operated by individual photons. Here we demonstrate experimentally that Stark-tuned Förster resonances can substantially increase this effective interaction between individual photons. This technique boosts the gain of a single-photon transistor to over 100, enhances the non-destructive detection of single Rydberg atoms to a fidelity beyond 0.8, and enables high-precision spectroscopy on Rydberg pair states. On top, we achieve a gain larger than 2 with gate photon read-out after the transistor operation. Theory models for Rydberg polariton propagation on Förster resonance and for the projection of the stored spin-wave yield excellent agreement to our data and successfully identify the main decoherence mechanism of the Rydberg transistor, paving the way towards photonic quantum gates. PMID:27515278

  15. Enhancement of Rydberg-mediated single-photon nonlinearities by electrically tuned Förster resonances.

    PubMed

    Gorniaczyk, H; Tresp, C; Bienias, P; Paris-Mandoki, A; Li, W; Mirgorodskiy, I; Büchler, H P; Lesanovsky, I; Hofferberth, S

    2016-01-01

    Mapping the strong interaction between Rydberg atoms onto single photons via electromagnetically induced transparency enables manipulation of light at the single-photon level and few-photon devices such as all-optical switches and transistors operated by individual photons. Here we demonstrate experimentally that Stark-tuned Förster resonances can substantially increase this effective interaction between individual photons. This technique boosts the gain of a single-photon transistor to over 100, enhances the non-destructive detection of single Rydberg atoms to a fidelity beyond 0.8, and enables high-precision spectroscopy on Rydberg pair states. On top, we achieve a gain larger than 2 with gate photon read-out after the transistor operation. Theory models for Rydberg polariton propagation on Förster resonance and for the projection of the stored spin-wave yield excellent agreement to our data and successfully identify the main decoherence mechanism of the Rydberg transistor, paving the way towards photonic quantum gates. PMID:27515278

  16. Physical modeling of interference enhanced imaging and characterization of single nanoparticles.

    PubMed

    Avci, Oguzhan; Adato, Ronen; Ozkumur, Ayca Yalcin; Ünlü, M Selim

    2016-03-21

    Interferometric imaging schemes have gained significant interest due to their superior sensitivity over imaging techniques that are solely based on scattered signal. In this study, we outline the theoretical foundations of imaging and characterization of single nanoparticles in an interferometric microscopy scheme, examine key parameters that influence the signal, and benchmark the model against experimental findings.

  17. Quantum private query based on single-photon interference

    NASA Astrophysics Data System (ADS)

    Xu, Sheng-Wei; Sun, Ying; Lin, Song

    2016-08-01

    Quantum private query (QPQ) has become a research hotspot recently. Specially, the quantum key distribution (QKD)-based QPQ attracts lots of attention because of its practicality. Various such kind of QPQ protocols have been proposed based on different technologies of quantum communications. Single-photon interference is one of such technologies, on which the famous QKD protocol GV95 is just based. In this paper, we propose two QPQ protocols based on single-photon interference. The first one is simpler and easier to realize, and the second one is loss tolerant and flexible, and more practical than the first one. Furthermore, we analyze both the user privacy and the database privacy in the proposed protocols.

  18. Single-Subject Experimental Design for Evidence-Based Practice

    ERIC Educational Resources Information Center

    Byiers, Breanne J.; Reichle, Joe; Symons, Frank J.

    2012-01-01

    Purpose: Single-subject experimental designs (SSEDs) represent an important tool in the development and implementation of evidence-based practice in communication sciences and disorders. The purpose of this article is to review the strategies and tactics of SSEDs and their application in speech-language pathology research. Method: The authors…

  19. Photonic RF vector signal generation with enhanced spectral efficiency using precoded double single-sideband modulation.

    PubMed

    Wang, Yuanquan; Chien, Hung-Chang; Guo, HaiChao; Yu, Jianjun; Chang, Gee-Kung; Chi, Nan

    2016-06-01

    In this study, a novel photonic vector signal at frequency (RF) bands generation scheme based on the beating of double single sidebands (SSBs) is proposed and experimentally demonstrated. The double SSBs carry separate constant- or multi-amplitude quadrature-amplitude-modulation vector signals are generated from a single I/Q modulator. By adopting phase and amplitude precoding, different constellations can be generated, such as 3-ary phase-shift keying (PSK), 4-PSK, 7-PSK, 8-PSK, and so on. In this work, 10-Gbaud 7-PSK vector signal generation at 20 GHz enabled by two precoded 4-PSK SSB signals via a single I/Q modulator is theoretically and experimentally investigated. Compared to a single-drive Mach-Zehnder modulator or conventional I/Q modulator-based photonic vector signal generation scheme, the spectrum efficiency can be doubled. Differential coding is also implemented at the transmitter side for accurate demodulation of 7-PSK into two 4-PSK signals. The bit-error ratio for 10-Gbaud 7-PSK vector signals can be under hard-decision forward-error-correction threshold of 3.8×10-3 after 10 km standard single-mode fiber transmission.

  20. The evolution of gadolinium based contrast agents: from single-modality to multi-modality.

    PubMed

    Zhang, Li; Liu, Ruiqing; Peng, Hui; Li, Penghui; Xu, Zushun; Whittaker, Andrew K

    2016-05-19

    Gadolinium-based contrast agents are extensively used as magnetic resonance imaging (MRI) contrast agents due to their outstanding signal enhancement and ease of chemical modification. However, it is increasingly recognized that information obtained from single modal molecular imaging cannot satisfy the higher requirements on the efficiency and accuracy for clinical diagnosis and medical research, due to its limitation and default rooted in single molecular imaging technique itself. To compensate for the deficiencies of single function magnetic resonance imaging contrast agents, the combination of multi-modality imaging has turned to be the research hotpot in recent years. This review presents an overview on the recent developments of the functionalization of gadolinium-based contrast agents, and their application in biomedicine applications. PMID:27159645

  1. The evolution of gadolinium based contrast agents: from single-modality to multi-modality

    NASA Astrophysics Data System (ADS)

    Zhang, Li; Liu, Ruiqing; Peng, Hui; Li, Penghui; Xu, Zushun; Whittaker, Andrew K.

    2016-05-01

    Gadolinium-based contrast agents are extensively used as magnetic resonance imaging (MRI) contrast agents due to their outstanding signal enhancement and ease of chemical modification. However, it is increasingly recognized that information obtained from single modal molecular imaging cannot satisfy the higher requirements on the efficiency and accuracy for clinical diagnosis and medical research, due to its limitation and default rooted in single molecular imaging technique itself. To compensate for the deficiencies of single function magnetic resonance imaging contrast agents, the combination of multi-modality imaging has turned to be the research hotpot in recent years. This review presents an overview on the recent developments of the functionalization of gadolinium-based contrast agents, and their application in biomedicine applications.

  2. Gradient-based enhancement of tubular structures in medical images.

    PubMed

    Moreno, Rodrigo; Smedby, Örjan

    2015-12-01

    Vesselness filters aim at enhancing tubular structures in medical images. The most popular vesselness filters are based on eigenanalyses of the Hessian matrix computed at different scales. However, Hessian-based methods have well-known limitations, most of them related to the use of second order derivatives. In this paper, we propose an alternative strategy in which ring-like patterns are sought in the local orientation distribution of the gradient. The method takes advantage of symmetry properties of ring-like patterns in the spherical harmonics domain. For bright vessels, gradients not pointing towards the center are filtered out from every local neighborhood in a first step. The opposite criterion is used for dark vessels. Afterwards, structuredness, evenness and uniformness measurements are computed from the power spectrum in spherical harmonics of both the original and the half-zeroed orientation distribution of the gradient. Finally, the features are combined into a single vesselness measurement. Alternatively, a structure tensor that is suitable for vesselness can be estimated before the analysis in spherical harmonics. The two proposed methods are called Ring Pattern Detector (RPD) and Filtered Structure Tensor (FST) respectively. Experimental results with computed tomography angiography data show that the proposed filters perform better compared to the state-of-the-art.

  3. Novel methods to enhance single strand conformation polymorphism (SSCP) senstivity and efficiency: Application to mutation detection in cystic fibrosis (CF)

    SciTech Connect

    Hagstrom, D.J.; Snow, K.; Yuan, Z.; Thibodeau, S.N.

    1994-09-01

    For single gene defects in which there are a variety of mutations with significant frequencies, it is a challenge to find an efficient and sensitive method for mutation detection. For example, although 70% to 75% of CF chromosomes in a North American Caucasian population have the mutation {delta}F508, more than 400 mutations (mostly single base pair substitutions) are represented on the remaining chromosomes. SSCP analysis is a relatively straightforward procedure and therefore suitable for routine use in a clinical laboratory. However, previous reports have demonstrated suboptimal sensitivity rates in screening for mutations. We have developed a novel set of conditions which greatly enhances sensitivity and efficiency of SSCP. Our protocol incorporates multiplex PCR, stepping of wattages during electrophoresis and increased salt concentration at the anode relative to the gel. To screen for mutations in the CFTR gene, three multiplex PCR reactions are performed using identical thermocycler parameters. Sizes of PCR products range from 441 bp to 196 bp: size differences of > 30 bp are necessary to ensure separation during electrophoresis. All PCR products are separated by electrophoresis at room temperature on a single gel containing 8% (37.5:1) polyacrylamide, 5% glycerol and 1x TBE. Using an anode buffer with increased salt (2x TBE) sharpens smaller sized bands, and stepping watts from 5W to 20W during electrophoresis enhances sensitivity. Positive controls were used to demonstrate that mutations could be detected. Other mutations or polymorphisms were verified by cycle sequencing of PCR products or by alternative PCR-based assays for the more common mutations. Thus, using 3 PCR reactions per patient and one gel condition, we are able to achieve a CF mutation detection rate of approximately 90% in a North American Caucasian population.

  4. Edge-Preserving Decomposition-Based Single Image Haze Removal.

    PubMed

    Li, Zhengguo; Zheng, Jinghong

    2015-12-01

    Single image haze removal is under-constrained, because the number of freedoms is larger than the number of observations. In this paper, a novel edge-preserving decomposition-based method is introduced to estimate transmission map for a haze image so as to design a single image haze removal algorithm from the Koschmiedars law without using any prior. In particular, weighted guided image filter is adopted to decompose simplified dark channel of the haze image into a base layer and a detail layer. The transmission map is estimated from the base layer, and it is applied to restore the haze-free image. The experimental results on different types of images, including haze images, underwater images, and normal images without haze, show the performance of the proposed algorithm.

  5. Single layer graphene band hybridization with silver nanoplates: Interplay between doping and plasmonic enhancement

    NASA Astrophysics Data System (ADS)

    Syed, Salmaan R.; Lim, Guh-Hwan; Flanders, Stuart J.; Taylor, Adam B.; Lim, Byungkwon; Chon, James W. M.

    2016-09-01

    In this paper, we report single layer graphene (SLG) hybridized with silver nanoplates, in which nanoplates act as either a charge doping or a field enhancement source for the SLG Raman spectrum. Surprisingly, the stiffening of both G and 2D peaks of more than 10 cm-1 was observed with no plasmonic enhancement of peaks, indicating that p-doping from nanoplates on SLG is occurring. Such observation is explained in terms of the contact separation distance between the graphene and the silver nanoplates being enough (˜4 Å) to cause a Fermi level shift in graphene to allow p-doping. When nanoplates were modified in shape with laser irradiation by either photothermal plasmon printing or laser induced ablation, the charge doping was lifted and the strong plasmonic enhancement of Raman signals was observed, indicating that the separation distance is increased. Further, when the nanoplates are oxidized, the two effects on the Raman bands of SLG are turned off, returning the Raman signals back to the original SLG state.

  6. Automatic segmentation of the liver from multi- and single-phase contrast-enhanced CT images.

    PubMed

    Ruskó, László; Bekes, György; Fidrich, Márta

    2009-12-01

    Segmentation of contrast-enhanced abdominal CT images is required by many clinical applications of computer aided diagnosis and therapy planning. The research on automated methods involves different organs among which the liver is the most emphasized. In the current clinical practice more images (at different phases) are acquired from the region of interest in case of a contrast-enhanced abdominal CT examination. The majority of the existing methods, however, use only the portal-venous image to segment the liver. This paper presents a method that automatically segments the liver by combining more phases of the contrast-enhanced CT examination. The method uses region-growing facilitated by pre- and post-processing functions, which incorporate anatomical and multi-phase information to eliminate over- and under-segmentation. Another method, which uses only the portal-venous phase to segment the liver automatically, is also presented. Both methods were evaluated using different datasets, which showed that the result of multi-phase method can be used without or after minor correction in nearly 94% of the cases, and the single-phase method can provide result comparable with non-expert manual segmentation in 90% of the cases. The comparison of the two methods demonstrates that automatic segmentation is more reliable when the information of more phases is combined.

  7. Demonstration of a single-crystal reflector-filter for enhancing slow neutron beams

    NASA Astrophysics Data System (ADS)

    Muhrer, G.; Schönfeldt, T.; Iverson, E. B.; Mocko, M.; Baxter, D. V.; Hügle, Th.; Gallmeier, F. X.; Klinkby, E. B.

    2016-09-01

    The cold polycrystalline beryllium reflector-filter concept has been used to enhance the cold neutron emission of cryogenic hydrogen moderators, while suppressing the intermediate wavelength and fast neutron emission at the same time. While suppressing the fast neutron emission is often desired, the suppression of intermediate wavelength neutrons is often unwelcome. It has been hypothesized that replacing the polycrystalline reflector-filter concept with a single-crystal reflector-filter concept would overcome the suppression of intermediate wavelength neutrons and thereby extend the usability of the reflector-filter concept to shorter but still important wavelengths. In this paper we present the first experimental data on a single-crystal reflector-filter at a reflected neutron source and compare experimental results with hypothesized performance. We find that a single-crystal reflector-filter retains the long-wavelength benefit of the polycrystalline reflector-filter, without suffering the same loss of important intermediate wavelength neutrons. This finding extends the applicability of the reflector-filter concept to intermediate wavelengths, and furthermore indicates that the reflector-filter benefits arise from its interaction with fast (background) neutrons, not with intermediate wavelength neutrons of potential interest in many types of neutron scattering.

  8. Demonstration of a Single-Crystal Reflector-Filter for Enhancing Slow Neutron Beams

    DOE PAGES

    Muhrer, Guenter; Schönfeldt, Troels; Iverson, Erik B.; Mocko, Michal; Baxter, David V.; Hügle, Thomas; Gallmeier, Franz X.; Klinkby, Esben

    2016-06-14

    The cold polycrystalline beryllium reflector-filter concept has been used to enhance the cold neutron emission of cryogenic hydrogen moderators, while suppressing the intermediate wavelength and fast neutron emission at the same time. While suppressing the fast neutron emission is often desired, the suppression of intermediate wavelength neutrons is often unwelcome. It has been hypothesized that replacing the polycrystalline reflector-filter concept with a single-crystal reflector-filter concept would overcome the suppression of intermediate wavelength neutrons and thereby extend the usability of the reflector-filter concept to shorter but still important wavelengths. In this paper we present the first experimental data on a single-crystalmore » reflector-filter and compare experimental results with hypothesized performance. We find that a single-crystal reflector-filter retains the long-wavelength benefit of the polycrystalline reflector-filter, without suffering the same loss of important intermediate wavelength neutrons. Ultimately, this finding extends the applicability of the reflector-filter concept to intermediate wavelengths, and furthermore indicates that the reflector-filter benefits arise from its interaction with fast (background) neutrons, not with intermediate wavelength neutrons of potential interest in many types of neutron scattering.« less

  9. Plasmofluidic single-molecule surface-enhanced Raman scattering from dynamic assembly of plasmonic nanoparticles

    NASA Astrophysics Data System (ADS)

    Patra, Partha Pratim; Chikkaraddy, Rohit; Tripathi, Ravi P. N.; Dasgupta, Arindam; Kumar, G. V. Pavan

    2014-07-01

    Single-molecule surface-enhanced Raman scattering (SM-SERS) is one of the vital applications of plasmonic nanoparticles. The SM-SERS sensitivity critically depends on plasmonic hot-spots created at the vicinity of such nanoparticles. In conventional fluid-phase SM-SERS experiments, plasmonic hot-spots are facilitated by chemical aggregation of nanoparticles. Such aggregation is usually irreversible, and hence, nanoparticles cannot be re-dispersed in the fluid for further use. Here, we show how to combine SM-SERS with plasmon polariton-assisted, reversible assembly of plasmonic nanoparticles at an unstructured metal-fluid interface. One of the unique features of our method is that we use a single evanescent-wave optical excitation for nanoparticle assembly, manipulation and SM-SERS measurements. Furthermore, by utilizing dual excitation of plasmons at metal-fluid interface, we create interacting assemblies of metal nanoparticles, which may be further harnessed in dynamic lithography of dispersed nanostructures. Our work will have implications in realizing optically addressable, plasmofluidic, single-molecule detection platforms.

  10. Plasmofluidic single-molecule surface-enhanced Raman scattering from dynamic assembly of plasmonic nanoparticles.

    PubMed

    Patra, Partha Pratim; Chikkaraddy, Rohit; Tripathi, Ravi P N; Dasgupta, Arindam; Kumar, G V Pavan

    2014-01-01

    Single-molecule surface-enhanced Raman scattering (SM-SERS) is one of the vital applications of plasmonic nanoparticles. The SM-SERS sensitivity critically depends on plasmonic hot-spots created at the vicinity of such nanoparticles. In conventional fluid-phase SM-SERS experiments, plasmonic hot-spots are facilitated by chemical aggregation of nanoparticles. Such aggregation is usually irreversible, and hence, nanoparticles cannot be re-dispersed in the fluid for further use. Here, we show how to combine SM-SERS with plasmon polariton-assisted, reversible assembly of plasmonic nanoparticles at an unstructured metal-fluid interface. One of the unique features of our method is that we use a single evanescent-wave optical excitation for nanoparticle assembly, manipulation and SM-SERS measurements. Furthermore, by utilizing dual excitation of plasmons at metal-fluid interface, we create interacting assemblies of metal nanoparticles, which may be further harnessed in dynamic lithography of dispersed nanostructures. Our work will have implications in realizing optically addressable, plasmofluidic, single-molecule detection platforms. PMID:25000476

  11. Enhanced ELISA based on carboxymethylated dextran coatings.

    PubMed

    Liberelle, Benoît; Fortier, Charles; De Crescenzo, Gregory

    2014-01-01

    In a "sandwich" enzyme-linked immunosorbent assay (ELISA) designed to detect an antigen in a complex protein mixture, the antigen is usually captured via an antibody adsorbed to the wells of a microplate. Plate preparation for standard assay involves a passive adsorption of capture antibodies followed by the incubation of blocking agents. Here, we describe a new strategy that replaces these two time-consuming adsorption steps (up to 15 h) by a unique step corresponding to the covalent grafting of the capture antibody on a carboxymethylated dextran (CMD) layer, a single step completed in 15 min. Taking advantage of the CMD low-fouling properties, blocking agent-free buffer solutions can be used as diluent in the improved approach.

  12. Parameter screening in microfluidics based hydrodynamic single-cell trapping.

    PubMed

    Deng, B; Li, X F; Chen, D Y; You, L D; Wang, J B; Chen, J

    2014-01-01

    Microfluidic cell-based arraying technology is widely used in the field of single-cell analysis. However, among developed devices, there is a compromise between cellular loading efficiencies and trapped cell densities, which deserves further analysis and optimization. To address this issue, the cell trapping efficiency of a microfluidic device with two parallel micro channels interconnected with cellular trapping sites was studied in this paper. By regulating channel inlet and outlet status, the microfluidic trapping structure can mimic key functioning units of previously reported devices. Numerical simulations were used to model this cellular trapping structure, quantifying the effects of channel on/off status and trapping structure geometries on the cellular trapping efficiency. Furthermore, the microfluidic device was fabricated based on conventional microfabrication and the cellular trapping efficiency was quantified in experiments. Experimental results showed that, besides geometry parameters, cellular travelling velocities and sizes also affected the single-cell trapping efficiency. By fine tuning parameters, more than 95% of trapping sites were taken by individual cells. This study may lay foundation in further studies of single-cell positioning in microfluidics and push forward the study of single-cell analysis.

  13. Transmission enhancement based on strong interference in metal-semiconductor layered film for energy harvesting

    NASA Astrophysics Data System (ADS)

    Li, Qiang; Du, Kaikai; Mao, Kening; Fang, Xu; Zhao, Ding; Ye, Hui; Qiu, Min

    2016-07-01

    A fundamental strategy to enhance optical transmission through a continuous metallic film based on strong interference dominated by interface phase shift is developed. In a metallic film coated with a thin semiconductor film, both transmission and absorption are simultaneously enhanced as a result of dramatically reduced reflection. For a 50-nm-thick Ag film, experimental transmission enhancement factors of 4.5 and 9.5 are realized by exploiting Ag/Si non-symmetric and Si/Ag/Si symmetric geometries, respectively. These planar layered films for transmission enhancement feature ultrathin thickness, broadband and wide-angle operation, and reduced resistance. Considering one of their potential applications as transparent metal electrodes in solar cells, a calculated 182% enhancement in the total transmission efficiency relative to a single metallic film is expected. This strategy relies on no patterned nanostructures and thereby may power up a wide spectrum of energy-harvesting applications such as thin-film photovoltaics and surface photocatalysis.

  14. Enhancing Trust in SOA Based Collaborative Environments

    NASA Astrophysics Data System (ADS)

    Boursas, Latifa; Bourimi, Mohamed; Hommel, Wolfgang; Kesdogan, Dogan

    Considering trust and privacy requirements for online and collaborative distance learning environments, this paper discusses potential extensions of SOA based applications to simultaneously support authentication and authorization services, and offering mutual trust to both learners and service providers. This study shows that the security mechanisms integrated in the SOA platform can be effectively extended and correlated with a trust model.

  15. Techniques for Enhancing Web-Based Education.

    ERIC Educational Resources Information Center

    Barbieri, Kathy; Mehringer, Susan

    The Virtual Workshop is a World Wide Web-based set of modules on high performance computing developed at the Cornell Theory Center (CTC) (New York). This approach reaches a large audience, leverages staff effort, and poses challenges for developing interesting presentation techniques. This paper describes the following techniques with their…

  16. Free base amino alcohols as electrostatic precipitator efficiency enhancers

    SciTech Connect

    Polizzotti, D.M.; Steelhammer, J.C.

    1980-12-16

    A method is disclosed for improving operation of an electrostatic precipitator. By adding free base amino alcohol to a particle-laden gas being treated by the precipitator, the efficiency of particle removal is significantly enhanced.

  17. Resolution enhancement of photon sieve based on apodization

    NASA Astrophysics Data System (ADS)

    Cheng, Guanxiao; Xing, Tingwen; Liao, Zhijie; Yang, Yong; Ma, Jianling

    2008-03-01

    Photon sieve is a novel diffractive optical element modulating either amplitude or phase which consists of a great number of pinholes distributed appropriately over the Fresnel zones for the focusing and imaging of light. Photon sieve has the advantages of the diameter of pinholes beyond the limitation of the corresponding Fresnel zone width and the minimum background in the focal plane. Furthermore, photon sieve can be fabricated on a single surface without any supporting struts required unlike the Fresnel zone plate. Photon sieve can be used as EUV telescope for solar orbiter, space-based surveillance telescope operating at visible light, or other imaging components. Photon sieve can also be used as one of the promising lithographic tools for nanoscale science and engineering to obtain the lower cost, higher flexibility and better resolution. The approaches to enhancing imaging resolution of photon sieve are presented in detail. According to Fresnel-Kirchhoff diffraction theory, the diffractive field of photon sieve is described by means of the discrete fast Fourier transform algorithm. The related contents include the calculation of point spread function, the suppression of side lobes, the imaging bandwidth, the physical limit of resolution, and the diffraction efficiency. Imaging properties of photon sieve are analyzed on the basis of precise test.

  18. Single protein sensing with asymmetric plasmonic hexamer via Fano resonance enhanced two-photon luminescence

    NASA Astrophysics Data System (ADS)

    Deng, Hai-Dong; Chen, Xing-Yu; Xu, Yi; Miroshnichenko, Andrey E.

    2015-12-01

    Fano resonances in plasmonic systems have been proved to facilitate various sensing applications in the nanoscale. In this work, we propose an experimental scheme to realize a single protein sensing by utilizing its two-photon luminescence enhanced by a plasmonic Fano resonance system. The asymmetric gold hexamer supporting polarization-dependent Fano resonances and plasmonic modes without in-plane rotational symmetry is used as a referenced spatial coordinate for bio-sensing. We demonstrate via the full-vectorial three-dimensional simulation that the moving direction and the spatial location of a protein can be detected via its two-photon luminescence, which benefits from the resonant near-field interaction with the electromagnetic hot-spots. The sensitivity to changes in position of our method is substantially better compared with the conventional linear sensing approach. Our strategy would facilitate the sensing, tracking and imaging of a single biomolecule in deep sub-wavelength scale and with a small optical extinction cross-section.Fano resonances in plasmonic systems have been proved to facilitate various sensing applications in the nanoscale. In this work, we propose an experimental scheme to realize a single protein sensing by utilizing its two-photon luminescence enhanced by a plasmonic Fano resonance system. The asymmetric gold hexamer supporting polarization-dependent Fano resonances and plasmonic modes without in-plane rotational symmetry is used as a referenced spatial coordinate for bio-sensing. We demonstrate via the full-vectorial three-dimensional simulation that the moving direction and the spatial location of a protein can be detected via its two-photon luminescence, which benefits from the resonant near-field interaction with the electromagnetic hot-spots. The sensitivity to changes in position of our method is substantially better compared with the conventional linear sensing approach. Our strategy would facilitate the sensing, tracking and

  19. Comparison of light out-coupling enhancements in single-layer blue-phosphorescent organic light emitting diodes using small-molecule or polymer hosts

    SciTech Connect

    Chang, Yung-Ting; Liu, Shun-Wei; Yuan, Chih-Hsien; Lee, Chih-Chien; Ho, Yu-Hsuan; Wei, Pei-Kuen; Chen, Kuan-Yu; Lee, Yi-Ting; Wu, Min-Fei; Chen, Chin-Ti E-mail: chihiwu@cc.ee.ntu.edu.tw; Wu, Chih-I E-mail: chihiwu@cc.ee.ntu.edu.tw

    2013-11-07

    Single-layer blue phosphorescence organic light emitting diodes (OLEDs) with either small-molecule or polymer hosts are fabricated using solution process and the performances of devices with different hosts are investigated. The small-molecule device exhibits luminous efficiency of 14.7 cd/A and maximum power efficiency of 8.39 lm/W, which is the highest among blue phosphorescence OLEDs with single-layer solution process and small molecular hosts. Using the same solution process for all devices, comparison of light out-coupling enhancement, with brightness enhancement film (BEF), between small-molecule and polymer based OLEDs is realized. Due to different dipole orientation and anisotropic refractive index, polymer-based OLEDs would trap less light than small molecule-based OLEDs internally, about 37% better based simulation results. In spite of better electrical and spectroscopic characteristics, including ambipolar characteristics, higher carrier mobility, higher photoluminescence quantum yield, and larger triplet state energy, the overall light out-coupling efficiency of small molecule-based devices is worse than that of polymer-based devices without BEF. However, with BEF for light out-coupling enhancement, the improved ratio in luminous flux and luminous efficiency for small molecule based device is 1.64 and 1.57, respectively, which are significantly better than those of PVK (poly-9-vinylcarbazole) devices. In addition to the theoretical optical simulation, the experimental data also confirm the origins of differential light-outcoupling enhancement. The maximum luminous efficiency and power efficiency are enhanced from 14.7 cd/A and 8.39 lm/W to 23 cd/A and 13.2 lm/W, respectively, with laminated BEF, which are both the highest so far for single-layer solution-process blue phosphorescence OLEDs with small molecule hosts.

  20. Design-Based Research and Technology-Enhanced Learning Environments

    ERIC Educational Resources Information Center

    Wang, Feng; Hannafin, Michael J.

    2005-01-01

    During the past decade, design-based research has demonstrated its potential as a methodology suitable to both research and design of technology-enhanced learning environments (TELEs). In this paper, we define and identify characteristics of design-based research, describe the importance of design-based research for the development of TELEs,…

  1. Robust image reconstruction enhancement based on Gaussian mixture model estimation

    NASA Astrophysics Data System (ADS)

    Zhao, Fan; Zhao, Jian; Han, Xizhen; Wang, He; Liu, Bochao

    2016-03-01

    The low quality of an image is often characterized by low contrast and blurred edge details. Gradients have a direct relationship with image edge details. More specifically, the larger the gradients, the clearer the image details become. Robust image reconstruction enhancement based on Gaussian mixture model estimation is proposed here. First, image is transformed to its gradient domain, obtaining the gradient histogram. Second, the gradient histogram is estimated and extended using a Gaussian mixture model, and the predetermined function is constructed. Then, using histogram specification technology, the gradient field is enhanced with the constraint of the predetermined function. Finally, a matrix sine transform-based method is applied to reconstruct the enhanced image from the enhanced gradient field. Experimental results show that the proposed algorithm can effectively enhance different types of images such as medical image, aerial image, and visible image, providing high-quality image information for high-level processing.

  2. Design of Reconfigurable Logic Circuits Based on Single-Layer Magnetic-Tunnel-Junction Elements

    NASA Astrophysics Data System (ADS)

    Lee, Seungyeon; Lee, Gamyoung; Lee, Hyunju; Lee, Seungjun; Shin, Hyungsoon

    2008-04-01

    Magnetologic using magnetic tunnel junction (MTJ) elements is one of the most promising logic technologies owing to its ease of integration and non-volatility. A magnetologic structure consisting of a single-layer MTJ and a current driver has been proposed by the same authors, which can provide enhanced functional flexibility and uniformity while requiring fewer fabrication steps. In this study, various merits of magnetologic using single-layer MTJ elements are fully exploited for the design of a reconfigurable logic device. A design of a reconfigurable 3-bit counter using single-layer MTJ is presented, which can be programmed to operate as a gray counter, an up counter, or a down counter. The functional correctness is verified by hspice simulation based on an hspice macromodel of MTJ that we have developed for a magnetologic design.

  3. Hybrid Graphene and Single-Walled Carbon Nanotube Films for Enhanced Phase-Change Heat Transfer.

    PubMed

    Seo, Han; Yun, Hyung Duk; Kwon, Soon-Yong; Bang, In Cheol

    2016-02-10

    Nucleate boiling is an effective heat transfer method in power generation systems and cooling devices. In this letter, hybrid graphene/single-walled carbon nanotube (SWCNT), graphene, and SWCNT films deposited on indium tin oxide (ITO) surfaces were fabricated to investigate the enhancement of nucleate boiling phenomena described by the critical heat flux and heat transfer coefficient. The graphene films were grown on Cu foils and transferred to ITO surfaces. Furthermore, SWCNTs were deposited on the graphene layer to fabricate hybrid graphene/SWCNT films. We determined that the hybrid graphene/SWCNT film deposited on an ITO surface is the most effective heat transfer surface in pool boiling because of the interconnected network of carbon structures.

  4. Graphene Enhances Li Storage Capacity of Porous Single-crystalline Silicon Nanowires

    SciTech Connect

    Wang, X.; Han, W.

    2010-12-01

    We demonstrated that graphene significantly enhances the reversible capacity of porous silicon nanowires used as the anode in Li-ion batteries. We prepared our experimental nanomaterials, viz., graphene and porous single-crystalline silicon nanowires, respectively, using a liquid-phase graphite exfoliation method and an electroless HF/AgNO{sub 3} etching process. The Si porous nanowire/graphene electrode realized a charge capacity of 2470 mAh g{sup -1} that is much higher than the 1256 mAh g{sup -1} of porous Si nanowire/C-black electrode and 6.6 times the theoretical capacity of commercial graphite. This relatively high capacity could originate from the favorable charge-transportation characteristics of the combination of graphene with the porous Si 1D nanostructure.

  5. Single frequency MOPA based on Nd:YAG single crystal fiber and rods.

    PubMed

    Liu, Zhaojun; Men, Shaojie; Liu, Yang; Cong, Zhenhua; Yang, Houwen; Cheng, Wenyong; Rao, Han; Lu, Jianren; Zhang, Xingyu

    2016-04-01

    We demonstrate a single frequency 1064 nm master oscillator power amplifier (MOPA) system operating in macro-micro pulse scheme. The repetition rate for the macro pulses was 300 Hz with pulse duration of 300 μs. Micro pulses operated at 25 kHz. The master laser was a single-longitudinal-mode electro-optically Q-switched Nd:YAG laser with an output power of 250 mW and pulse duration of 33 ns. Three stages of power amplifiers based on Nd:YAG single crystal fiber and rods were designed. The final output power reached 31.3 W with pulse duration of 30 ns and linewidth of less than 130 MHz. Micro pulse energy of 13.9 mJ was obtained with a peak power of up to 464 kW. The beam quality factors (M2) were measured to be 1.56 and 1.76 in horizontal and vertical directions, respectively. PMID:27192235

  6. Compton imager based on a single planar segmented HPGe detector

    NASA Astrophysics Data System (ADS)

    Khaplanov, A.; Pettersson, J.; Cederwall, B.

    2007-10-01

    A collimator-free Compton imaging system has been developed based on a single high-purity germanium detector and used to generate images of radioactive sources emitting γ rays. The detector has a planar crystal with one pixellated contact with a total of 25 segments. Pulse shape analysis has been applied to achieve a 3D-position sensitivity of the detector. The first imaging results from this detector are presented, based on the reconstruction of events where a γ ray is fully absorbed after scattering between adjacent segments.

  7. Enhancing synchronization based on complex gradient networks.

    PubMed

    Wang, Xingang; Lai, Ying-Cheng; Lai, Choy Heng

    2007-05-01

    The ubiquity of scale-free networks in nature and technological applications and the finding that such networks may be more difficult to synchronize than homogeneous networks pose an interesting phenomenon for study in network science. We argue and demonstrate that, in the presence of some proper gradient fields, scale-free networks can be more synchronizable than homogeneous networks. The gradient structure can in fact arise naturally in any weighted and asymmetrical networks; based on this we propose a coupling scheme that permits effective synchronous dynamics on the network. The synchronization scheme is verified by eigenvalue analysis and by direct numerical simulations using networks of nonidentical chaotic oscillators. PMID:17677146

  8. Atomically thick bismuth selenide freestanding single layers achieving enhanced thermoelectric energy harvesting.

    PubMed

    Sun, Yongfu; Cheng, Hao; Gao, Shan; Liu, Qinghua; Sun, Zhihu; Xiao, Chong; Wu, Changzheng; Wei, Shiqiang; Xie, Yi

    2012-12-19

    Thermoelectric materials can realize significant energy savings by generating electricity from untapped waste heat. However, the coupling of the thermoelectric parameters unfortunately limits their efficiency and practical applications. Here, a single-layer-based (SLB) composite fabricated from atomically thick single layers was proposed to optimize the thermoelectric parameters fully. Freestanding five-atom-thick Bi(2)Se(3) single layers were first synthesized via a scalable interaction/exfoliation strategy. As revealed by X-ray absorption fine structure spectroscopy and first-principles calculations, surface distortion gives them excellent structural stability and a much increased density of states, resulting in a 2-fold higher electrical conductivity relative to the bulk material. Also, the surface disorder and numerous interfaces in the Bi(2)Se(3) SLB composite allow for effective phonon scattering and decreased thermal conductivity, while the 2D electron gas and energy filtering effect increase the Seebeck coefficient, resulting in an 8-fold higher figure of merit (ZT) relative to the bulk material. This work develops a facile strategy for synthesizing atomically thick single layers and demonstrates their superior ability to optimize the thermoelectric energy harvesting.

  9. Single-Tailed Lipidoids Enhance the Transfection Activity of Their Double-Tailed Counterparts.

    PubMed

    Wu, Yihang; Li, Linxian; Chen, Qing; Su, Yi; Levkin, Pavel A; Davidson, Gary

    2016-01-11

    Cationic lipid-like molecules (lipidoids) are widely used for in vitro and in vivo gene delivery. Nearly all lipidoids developed to date employ double-tail or multiple-tail structures for transfection. Single-tail lipidoids are seldom considered for transfection as they have low efficiency in gene delivery. So far, there is no detailed study on the contribution to transfection efficiency of single-tail lipidoids when combined with standard double-tail lipidoids. Here, we use combinatorial chemistry to synthesize 17 double-tail and 17 single-tail lipidoids using thiol-yne and thiol-ene click chemistry, respectively. HEK 293T cells were used to analyze transfection efficiency by fluorescence microscopy and calculated based on the percentage of cells transfected. The size and zeta potential of liposomes and lipoplexes were characterized by dynamic light scattering (DLS). Intracellular DNA delivery and trafficking was further examined using confocal microscopy. Our study shows that combining single with double-tail lipidoids increases uptake of lipoplexes, as well as cellular transfection efficiency.

  10. Anisotropy of nickel-base superalloy single crystals

    NASA Technical Reports Server (NTRS)

    Mackay, R. A.; Dreshfield, R. L.; Maier, R. D.

    1980-01-01

    The influence of orientation on the tensile and stress rupture behavior of 52 Mar-M247 single crystals was studied. Tensile tests were performed at temperatures between 23 and 1093 C; stress rupture behavior was examined between 760 and 1038 C. The mechanical behavior of the single crystals was rationalized on the basis of the Schmid factor contours for the operative slip systems and the lattice rotations which the crystals underwent during deformation. The tensile properties correlated well with the appropriate Schmid factor contours. The stress rupture lives at lower testing temperatures were greatly influenced by the lattice rotations required to produce cross slip. A unified analysis was attained for the stress rupture life data generated for the Mar-M247 single crystals at 760 and 774 C under a stress of 724 MPa and the data reported for Mar-M200 single crystals tested at 760 C under a stress of 689 MPa. Based on this analysis, the stereographic triangle was divided into several regions which were rank ordered according to stress rupture life for this temperature regime.

  11. Anisotropy of nickel-base superalloy single crystals

    NASA Technical Reports Server (NTRS)

    Mackay, R. A.; Maier, R. D.; Dreshfield, R. L.

    1980-01-01

    The effects of crystal orientation on the mechanical properties of single crystals of the nickel-based superalloy Mar-M247 are investigated. Tensile tests at temperatures from 23 to 1093 C and stress rupture tests at temperatures from 760 to 1038 C were performed for 52 single crystals at various orientations. During tensile testing between 23 and 760 C, single crystals with high Schmid factors were found to be favorably oriented for slip and to exhibit lower strength and higher ductility than those with low Schmid factors. Crystals which required large rotations to become oriented for cross slip were observed to have the shortest stress rupture lives at 760 C, while those which required little or no rotation had the longest lives. In addition, stereographic triangles obtained for Mar-M247 and Mar-M200 single crystals reveal that crystals with orientations near the -111 had the highest lives, those near the 001 had high lives, and those near the 011 had low lives.

  12. Single particle optical investigation of gold shell enhanced upconverted fluorescence emission

    NASA Astrophysics Data System (ADS)

    Green, Kory; Lim, Shuang Fang; Hallen, Hans

    2014-03-01

    Upconverting nanoparticles (UCNPs) excited in the near IR offer novel advantages as fluorescent contrast agents, allowing for background free bio-imaging. However, their fluorescence brightness is hampered by low quantum efficiency due to the low absorption cross section of Ytterbium and Erbium ions in the near IR. We enhance the efficiency of these particles by investigating the plasmonic coupling of 30nm diameter core NaYF4: Yb, Er upconverting particles (UCNPs) with a gold shell coating. An enhancement of green emission by a factor of five and a three times overall increase in emission intensity has been achieved for single particle spectra. UV-Vis absorption has confirmed the surface plasmon resonance (SPR) of the gold shell to the near IR and transmission electron microscope (TEM) images demonstrates successful growth of a gold shell around the upconversion particle. Time-resolved spectroscopy shows that gold shell coupling changes the lifetime of the energy levels of the Erbium ion that are relevant to the emission process.

  13. Enhanced Hydrogen Production Integrated with CO2 Separation in a Single-Stage Reactor

    SciTech Connect

    Mahesh Iyer; Himanshu Gupta; Danny Wong; Liang-Shih Fan

    2005-09-30

    Hydrogen production from coal gasification can be enhanced by driving the equilibrium limited Water Gas Shift reaction forward by incessantly removing the CO{sub 2} by-product via the carbonation of calcium oxide. This project aims at using the OSU patented high-reactivity mesoporous precipitated calcium carbonate sorbent for removing the CO{sub 2} product. Preliminary experiments demonstrate the show the superior performance of the PCC sorbent over other naturally occurring calcium sorbents. Gas composition analyses show the formation of 100% pure hydrogen. Novel calcination techniques could lead to smaller reactor footprint and single-stage reactors that can achieve maximum theoretical H{sub 2} production for multicyclic applications. Sub-atmospheric calcination studies reveal the effect of vacuum level, diluent gas flow rate, thermal properties of the diluent gas and the sorbent loading on the calcination kinetics which play an important role on the sorbent morphology. Steam, which can be easily separated from CO{sub 2}, is envisioned to be a potential diluent gas due to its enhanced thermal properties. Steam calcination studies at 700-850 C reveal improved sorbent morphology over regular nitrogen calcination. A mixture of 80% steam and 20% CO{sub 2} at ambient pressure was used to calcine the spent sorbent at 820 C thus lowering the calcination temperature. Regeneration of calcium sulfide to calcium carbonate was achieved by carbonating the calcium sulfide slurry by bubbling CO{sub 2} gas at room temperature.

  14. Sweeter and stronger: enhancing sweetness and stability of the single chain monellin MNEI through molecular design

    PubMed Central

    Leone, Serena; Pica, Andrea; Merlino, Antonello; Sannino, Filomena; Temussi, Piero Andrea; Picone, Delia

    2016-01-01

    Sweet proteins are a family of proteins with no structure or sequence homology, able to elicit a sweet sensation in humans through their interaction with the dimeric T1R2-T1R3 sweet receptor. In particular, monellin and its single chain derivative (MNEI) are among the sweetest proteins known to men. Starting from a careful analysis of the surface electrostatic potentials, we have designed new mutants of MNEI with enhanced sweetness. Then, we have included in the most promising variant the stabilising mutation E23Q, obtaining a construct with enhanced performances, which combines extreme sweetness to high, pH-independent, thermal stability. The resulting mutant, with a sweetness threshold of only 0.28 mg/L (25 nM) is the strongest sweetener known to date. All the new proteins have been produced and purified and the structures of the most powerful mutants have been solved by X-ray crystallography. Docking studies have then confirmed the rationale of their interaction with the human sweet receptor, hinting at a previously unpredicted role of plasticity in said interaction. PMID:27658853

  15. Enhancement of BOLD-contrast sensitivity by single-shot multi-echo functional MR imaging.

    PubMed

    Posse, S; Wiese, S; Gembris, D; Mathiak, K; Kessler, C; Grosse-Ruyken, M L; Elghahwagi, B; Richards, T; Dager, S R; Kiselev, V G

    1999-07-01

    Improved data acquisition and processing strategies for blood oxygenation level-dependent (BOLD)-contrast functional magnetic resonance imaging (fMRI), which enhance the functional contrast-to-noise ratio (CNR) by sampling multiple echo times in a single shot, are described. The dependence of the CNR on T2*, the image encoding time, and the number of sampled echo times are investigated for exponential fitting, echo summation, weighted echo summation, and averaging of correlation maps obtained at different echo times. The method is validated in vivo using visual stimulation and turbo proton echoplanar spectroscopic imaging (turbo-PEPSI), a new single-shot multi-slice MR spectroscopic imaging technique, which acquires up to 12 consecutive echoplanar images with echo times ranging from 12 to 213 msec. Quantitative T2*-mapping significantly increases the measured extent of activation and the mean correlation coefficient compared with conventional echoplanar imaging. The sensitivity gain with echo summation, which is computationally efficient provides similar sensitivity as fitting. For all data processing methods sensitivity is optimum when echo times up to 3.2 T2* are sampled. This methodology has implications for comparing functional sensitivity at different magnetic field strengths and between brain regions with different magnetic field inhomogeneities.

  16. Single protein sensing with asymmetric plasmonic hexamer via Fano resonance enhanced two-photon luminescence.

    PubMed

    Deng, Hai-Dong; Chen, Xing-Yu; Xu, Yi; Miroshnichenko, Andrey E

    2015-12-28

    Fano resonances in plasmonic systems have been proved to facilitate various sensing applications in the nanoscale. In this work, we propose an experimental scheme to realize a single protein sensing by utilizing its two-photon luminescence enhanced by a plasmonic Fano resonance system. The asymmetric gold hexamer supporting polarization-dependent Fano resonances and plasmonic modes without in-plane rotational symmetry is used as a referenced spatial coordinate for bio-sensing. We demonstrate via the full-vectorial three-dimensional simulation that the moving direction and the spatial location of a protein can be detected via its two-photon luminescence, which benefits from the resonant near-field interaction with the electromagnetic hot-spots. The sensitivity to changes in position of our method is substantially better compared with the conventional linear sensing approach. Our strategy would facilitate the sensing, tracking and imaging of a single biomolecule in deep sub-wavelength scale and with a small optical extinction cross-section.

  17. Enhancement of BOLD-contrast sensitivity by single-shot multi-echo functional MR imaging.

    PubMed

    Posse, S; Wiese, S; Gembris, D; Mathiak, K; Kessler, C; Grosse-Ruyken, M L; Elghahwagi, B; Richards, T; Dager, S R; Kiselev, V G

    1999-07-01

    Improved data acquisition and processing strategies for blood oxygenation level-dependent (BOLD)-contrast functional magnetic resonance imaging (fMRI), which enhance the functional contrast-to-noise ratio (CNR) by sampling multiple echo times in a single shot, are described. The dependence of the CNR on T2*, the image encoding time, and the number of sampled echo times are investigated for exponential fitting, echo summation, weighted echo summation, and averaging of correlation maps obtained at different echo times. The method is validated in vivo using visual stimulation and turbo proton echoplanar spectroscopic imaging (turbo-PEPSI), a new single-shot multi-slice MR spectroscopic imaging technique, which acquires up to 12 consecutive echoplanar images with echo times ranging from 12 to 213 msec. Quantitative T2*-mapping significantly increases the measured extent of activation and the mean correlation coefficient compared with conventional echoplanar imaging. The sensitivity gain with echo summation, which is computationally efficient provides similar sensitivity as fitting. For all data processing methods sensitivity is optimum when echo times up to 3.2 T2* are sampled. This methodology has implications for comparing functional sensitivity at different magnetic field strengths and between brain regions with different magnetic field inhomogeneities. PMID:10398954

  18. Analysis of Convective Heat Transfer Enhancement by Nanofluids: Single-Phase and Two-Phase Treatments

    NASA Astrophysics Data System (ADS)

    Kakaç, S.; Pramuanjaroenkij, A.

    2016-05-01

    Nanofluids have been investigated regarding their advantages and potentialities for the purpose of increasing convective heat transfer rates inside thermal systems where they are used as working fluids. Researchers in thermophysics have investigated these fluids experimentally and numerically. This review provides extensive theoretical information concerning nanofluids in the single-phase and two-phase treatments. Important published works on nanofluid properties and correlations are summarized and reviewed in detail. Heat transfer enhancement by nanofluids is a challenging problem due to the difficulties inherent in the model of the physical mechanism of interaction between the paricles. Here the interaction between the phases is modeled by several two-phase models, and the results are given in graphical and tabular forms. Despite the advantages of the mixture model, such as imlementation of physical properties and less computational power requirements, some studies showed that the results of the single-phase and two-phase models are very similar. The main difference consists in the effect of the drift velocities of the phases relative to each other.

  19. On the critical role of Rayleigh scattering in single-molecule surface-enhanced Raman scattering via a plasmonic nanogap.

    PubMed

    Chen, Bao-Qin; Zhang, Chao; Li, Jiafang; Li, Zhi-Yuan; Xia, Younan

    2016-08-25

    Electromagnetic and chemical enhancement mechanisms are commonly used to account for single-molecule surface-enhanced Raman scattering (SM-SERS). Due to many practical limitations, however, the overall enhancement factor summed up from these two mechanisms is typically 5-6 orders of magnitude below the level of 10(14)-10(15) required for SM-SERS. Here, we demonstrate that the multiple elastic Rayleigh scattering of a molecule could play a critical role in further enhancing the Raman signal, when the molecule is trapped in a 2 nm gap between two Ag nanoparticles, pushing the overall enhancement factor close to the level needed for SM-SERS. As a universal physical process for all molecules interacting with light, we believe that Rayleigh scattering plays a pivotal and as yet unrecognized role in SERS, in particular, for enabling single-molecule sensitivity. PMID:27526632

  20. Single Wall Carbon Nanotube-Based Structural Health Sensing Materials

    NASA Technical Reports Server (NTRS)

    Watkins, A. Neal; Ingram, JoAnne L.; Jordan, Jeffrey D.; Wincheski, Russell A.; Smits, Jan M.; Williams, Phillip A.

    2004-01-01

    Single wall carbon nanotube (SWCNT)-based materials represent the future aerospace vehicle construction material of choice based primarily on predicted strength-to-weight advantages and inherent multifunctionality. The multifunctionality of SWCNTs arises from the ability of the nanotubes to be either metallic or semi-conducting based on their chirality. Furthermore, simply changing the environment around a SWCNT can change its conducting behavior. This phenomenon is being exploited to create sensors capable of measuring several parameters related to vehicle structural health (i.e. strain, pressure, temperature, etc.) The structural health monitor is constructed using conventional electron-beam lithographic and photolithographic techniques to place specific electrode patterns on a surface. SWCNTs are then deposited between the electrodes using a dielectrophoretic alignment technique. Prototypes have been constructed on both silicon and polyimide substrates, demonstrating that surface-mountable and multifunctional devices based on SWCNTs can be realized.

  1. New concepts for strength enhancement of co-cured composite single lap joints

    NASA Astrophysics Data System (ADS)

    Coates, Cameron Wayne

    2001-10-01

    Often the benefits of utilizing composites are diminished by the poor performance of their joint designs. This research examines designs that seek to improve the performance of composite co-cured single lap joints under static and fatigue loading, with only minor alteration to the geometry or lay-up of a base design. The minor alteration criterion was chosen in order to reduce the cost of implementing these designs in replacing existing joints or altering existing manufacturing methods. The approach consisted of two phases, denoted Phase I and II. Phase I consisted of monotonic tests for all the proposed designs as well as Finite Element Analysis of the design showing the most improvement. The objective of Phase I was to determine whether the designs would improve monotonic strength at the joint interface and identify the most effective designs. The designs tested during Phase I may be categorized as Single Nested Overlap, Half Slice, Full Slice and Transverse Layer. The preliminary tests consisted of single lap joint composites with altered and unaltered interfaces tested under uniform extension. The configurations examined include a quasi-isotropic lay-up and a unidirectional lay-up, however the designs are applicable to any lay-up. A comparison of ultimate strengths indicated that these designs offered improvement in strength. During testing, acoustic emission equipment was used to monitor damage progression as well as detect damage initiation and accumulation. The most consistent and practical design improvements were determined to be the Single Nested Overlap and Transverse Layer configurations. A Finite Element Analysis (FEA) of the Reference joint and the Single Nested Overlap joint was performed. FE predictions of the effectiveness of the nested overlap design support the test data through a reduction in shear stress and a reversal of peel stresses.

  2. Single Sagnac's Interferometers Instrumentation, based in the Best Detection Limit.

    NASA Astrophysics Data System (ADS)

    Palma-Vargas, Salvador; Ramírez-Ibarra, Angélica; Sandoval-Romero, G. Eduardo

    2008-04-01

    An interferometric system of volume optics and fiber optic were constructed and proved, showing the instrumentation technique made for these devices, supported in the new technologies of optical detection, amplification, analogical and digital filtrate and single data acquisition. Based on the Sagnac's effect of volume optics and fiber optic, the interferometer of Sagnac has many applications, nevertheless the methods of construction, design and instrumentation for the sensors manufacture of based on both designs are not very well-known, is for that reason that in this work approaches some of the methodologies for the design and construction of these devices, obtaining higher sensitivity and better contribution in its respective interferometric paths, for the sensing of different physical parameters in which they are applied. We used the single design for each interferometer, proposing the best detection limit for each one. The data acquisition was made with the proposal to obtain quick results, using the audio card of a PC, obtaining a real time measurements and digital processing of the signal in a single way.

  3. Enhancing and initiating phage-based therapies

    PubMed Central

    Serwer, Philip; Wright, Elena T; Chang, Juan T; Liu, Xiangan

    2014-01-01

    Drug development has typically been a primary foundation of strategy for systematic, long-range management of pathogenic cells. However, drug development is limited in speed and flexibility when response is needed to changes in pathogenic cells, especially changes that produce drug-resistance. The high replication speed and high diversity of phages are potentially useful for increasing both response speed and response flexibility when changes occur in either drug resistance or other aspects of pathogenic cells. We present strategy, with some empirical details, for (1) using modern molecular biology and biophysics to access these advantages during the phage therapy of bacterial infections, and (2) initiating use of phage capsid-based drug delivery vehicles (DDVs) with procedures that potentially overcome both drug resistance and other present limitations in the use of DDVs for the therapy of neoplasms. The discussion of phage therapy includes (a) historical considerations, (b) changes that appear to be needed in clinical tests if use of phage therapy is to be expanded, (c) recent work on novel phages and its potential use for expanding the capabilities of phage therapy and (d) an outline for a strategy that encompasses both theory and practice for expanding the applications of phage therapy. The discussion of DDVs starts by reviewing current work on DDVs, including work on both liposomal and viral DDVs. The discussion concludes with some details of the potential use of permeability constrained phage capsids as DDVs. PMID:26713220

  4. Variational contrast enhancement guided by global and local contrast measurements for single-image defogging

    NASA Astrophysics Data System (ADS)

    Zhou, Li; Bi, Du-Yan; He, Lin-Yuan

    2015-01-01

    The visibility of images captured in foggy conditions is impaired severely by a decrease in the contrasts of objects and veiling with a characteristic gray hue, which may limit the performance of visual applications out of doors. Contrast enhancement together with color restoration is a challenging mission for conventional fog-removal methods, as the degrading effect of fog is largely dependent on scene depth information. Nowadays, people change their minds by establishing a variational framework for contrast enhancement based on a physically based analytical model, unexpectedly resulting in color distortion, dark-patch distortion, or fuzzy features of local regions. Unlike previous work, our method treats an atmospheric veil as a scattering disturbance and formulates a foggy image as an energy functional minimization to estimate direct attenuation, originating from the work of image denoising. In addition to a global contrast measurement based on a total variation norm, an additional local measurement is designed in that optimal problem for the purpose of digging out more local details as well as suppressing dark-patch distortion. Moreover, we estimate the airlight precisely by maximization with a geometric constraint and a natural image prior in order to protect the faithfulness of the scene color. With the estimated direct attenuation and airlight, the fog-free image can be restored. Finally, our method is tested on several benchmark and realistic images evaluated by two assessment approaches. The experimental results imply that our proposed method works well compared with the state-of-the-art defogging methods.

  5. Raman scattering enhanced by plasmonic clusters and its application to single-molecule imaging

    SciTech Connect

    Yasuike, Tomokazu; Nobusada, Katsuyuki

    2015-12-31

    The optical response of the linear Au{sub 8} cluster is investigated by the linear response theory based on the density functional theory. It is revealed that the observed many peaks in the visible region originate from the interaction of the ideal plasmonic excitation along the molecular axis with the background d-electron excitations, i.e., the Landau damping. In spite of the existence of the damping, the Raman scattering is shown to be enhanced remarkably by the incident light resonant to the visible excitations. The novel imaging experiment with the atomic resolution is proposed by utilizing a plasmonic cluster as the probing tip.

  6. Visual Contrast Enhancement Algorithm Based on Histogram Equalization

    PubMed Central

    Ting, Chih-Chung; Wu, Bing-Fei; Chung, Meng-Liang; Chiu, Chung-Cheng; Wu, Ya-Ching

    2015-01-01

    Image enhancement techniques primarily improve the contrast of an image to lend it a better appearance. One of the popular enhancement methods is histogram equalization (HE) because of its simplicity and effectiveness. However, it is rarely applied to consumer electronics products because it can cause excessive contrast enhancement and feature loss problems. These problems make the images processed by HE look unnatural and introduce unwanted artifacts in them. In this study, a visual contrast enhancement algorithm (VCEA) based on HE is proposed. VCEA considers the requirements of the human visual perception in order to address the drawbacks of HE. It effectively solves the excessive contrast enhancement problem by adjusting the spaces between two adjacent gray values of the HE histogram. In addition, VCEA reduces the effects of the feature loss problem by using the obtained spaces. Furthermore, VCEA enhances the detailed textures of an image to generate an enhanced image with better visual quality. Experimental results show that images obtained by applying VCEA have higher contrast and are more suited to human visual perception than those processed by HE and other HE-based methods. PMID:26184219

  7. Performance Enhancement Using Selective Reinforcement for Metallic Single- and Multi-Pin Loaded Holes

    NASA Technical Reports Server (NTRS)

    Farley, Gary L.; Seshadri, Banavara R.

    2005-01-01

    An analysis based investigation of aluminum with metal matrix composite selectively reinforced single- and multi-hole specimens was performed and their results compared with results from geometrically comparable non-reinforced specimens. All reinforced specimens exhibited a significant increase in performance. Performance increase of up to 170 percent was achieved. Specimen failure modes were consistent with results from reinforced polymeric matrix composite specimens. Localized reinforcement application (circular) proved as effective as a broader area (strip) reinforcement. Also, selective reinforcement is an excellent method of increasing the performance of multi-hole specimens.

  8. Temperature and Enhanced Adduct Mobility on the Growth of MMTWNMP Single Crystals

    NASA Astrophysics Data System (ADS)

    Srinivasan, R.; Raghavan, C. M.; Saravanan, L.; Jayavel, R.; Baskar, K.

    2011-07-01

    A novel organometallic nonlinear optical crystal material; diaquatetrakis (thiocyanato) manganese (II) mercury (II)-N-methyl-2-pyrrolidone, MnHg(SCN)4(H2O)2.2(C3H6CONCH3), (abbreviated as MMTWNMP) of very good transparency was grown by low temperature solution growth method. The improvement on the quality of the single crystal was analyzed and explained based on the temperature effect and the mobility of adduct N-Methyl Pyrrolidone molecules. A mechanism for the basic mass transport is proposed and reasoned.

  9. Digital speech enhancement based on DTOMP and adaptive quantile

    NASA Astrophysics Data System (ADS)

    Wang, Anna; Zhou, Xiaoxing; Xue, Changliang; Sun, Xiyan; Sun, Hongying

    2013-03-01

    Compressed Sensing (CS) that can effectively extract the information contained in the signal is a new sampling theory based on signal sparseness. This paper applies CS theory in digital speech signal enhancement processing, proposes an adaptive quantile method for the noise power estimation and combines the improved double-threshold orthogonal matching pursuit algorithm for speech reconstruction, then achieves speech enhancement processing. Compared with the simulation results of the spectral subtraction and the subspace algorithm, the experiment results verify the feasibility and effectiveness of the algorithm proposed in this paper applied to speech enhancement processing.

  10. Mesoporous TiO2 single crystals delivering enhanced mobility and optoelectronic device performance.

    PubMed

    Crossland, Edward J W; Noel, Nakita; Sivaram, Varun; Leijtens, Tomas; Alexander-Webber, Jack A; Snaith, Henry J

    2013-03-14

    Mesoporous ceramics and semiconductors enable low-cost solar power, solar fuel, (photo)catalyst and electrical energy storage technologies. State-of-the-art, printable high-surface-area electrodes are fabricated from thermally sintered pre-formed nanocrystals. Mesoporosity provides the desired highly accessible surfaces but many applications also demand long-range electronic connectivity and structural coherence. A mesoporous single-crystal (MSC) semiconductor can meet both criteria. Here we demonstrate a general synthetic method of growing semiconductor MSCs of anatase TiO2 based on seeded nucleation and growth inside a mesoporous template immersed in a dilute reaction solution. We show that both isolated MSCs and ensembles incorporated into films have substantially higher conductivities and electron mobilities than does nanocrystalline TiO2. Conventional nanocrystals, unlike MSCs, require in-film thermal sintering to reinforce electronic contact between particles, thus increasing fabrication cost, limiting the use of flexible substrates and precluding, for instance, multijunction solar cell processing. Using MSC films processed entirely below 150 °C, we have fabricated all-solid-state, low-temperature sensitized solar cells that have 7.3 per cent efficiency, the highest efficiency yet reported. These high-surface-area anatase single crystals will find application in many different technologies, and this generic synthetic strategy extends the possibility of mesoporous single-crystal growth to a range of functional ceramics and semiconductors.

  11. Chemical monitors based on Surface-Enhanced Raman Scattering (SERS)

    SciTech Connect

    Vo-Dinh, T.; Alarie, J.P.; Sutherland, W.S.; Stokes, D.L.; Miller, G.H.

    1992-12-31

    This paper presents an overview of the development of chemical monitors using the Surface-Enhanced Raman Scattering (SERS) technique. The SERS effect is based on recent experimental observations, which have indicated enhancement of the Raman scattering efficiency by factors up to 10{sup 8} when a compound is adsorbed on rough metallic surfaces having submicron protrusions. The focus of our research efforts is on the development of SERS-active sensors and instrumentation capable of field analysis and remote sensing.

  12. Single optical tweezers based on elliptical core fiber

    NASA Astrophysics Data System (ADS)

    Zhang, Yu; Zhao, Li; Chen, Yunhao; Liu, Zhihai; Zhang, Yaxun; Zhao, Enming; Yang, Jun; Yuan, Libo

    2016-04-01

    We propose and demonstrate a new single optical tweezers based on an elliptical core fiber, which can realize the trapped yeast cell rotation with a precise and simple control. Due to the elliptical shape of the fiber core, the LP11 mode beam can propagate stably. When we rotate the fiber tip, the LP11 mode beam will also rotate along with the fiber tip, which helps to realize the trapped micro-particle rotation. By using this method, we can easily realize the rotation of the trapped yeast cells, the rotating angle of the yeast cell is same as the elliptical core fiber tip.

  13. Single-cell Genomics using Droplet-based Microfluidics

    NASA Astrophysics Data System (ADS)

    Basu, Anindita; Macosko, Evan; Shalek, Alex; McCarroll, Steven; Regev, Aviv; Weitz, Dave

    2014-03-01

    We develop a system to profile the transcriptome of mammalian cells in isolation using reverse emulsion droplet-based microfluidic techniques. This is accomplished by (a) encapsulating and lysing one cell per emulsion droplet, and (b) uniquely barcoding the RNA contents from each cell using unique DNA-barcoded microgel beads. This enables us to study the transcriptional behavior of a large number of cells at single-cell resolution. We then use these techniques to study transcriptional responses of isolated immune cells to precisely controlled chemical and pathological stimuli provided in the emulsion droplet.

  14. A Sensitivity-Enhanced Refractive Index Sensor Using a Single-Mode Thin-Core Fiber Incorporating an Abrupt Taper

    PubMed Central

    Shi, Jie; Xiao, Shilin; Yi, Lilin; Bi, Meihua

    2012-01-01

    A sensitivity-enhanced fiber-optic refractive index (RI) sensor based on a tapered single-mode thin-core diameter fiber is proposed and experimentally demonstrated. The sensor head is formed by splicing a section of tapered thin-core diameter fiber (TCF) between two sections of single-mode fibers (SMFs). The cladding modes are excited at the first SMF-TCF interface, and then interfere with the core mode at the second interface, thus forming an inter-modal interferometer (IMI). An abrupt taper (tens of micrometers long) made by the electric-arc-heating method is utilized, and plays an important role in improving sensing sensitivity. The whole manufacture process only involves fiber splicing and tapering, and all the fabrication process can be achieved by a commercial fiber fusion splicer. Using glycerol and water mixture solution as an example, the experimental results show that the refractive index sensitivity is measured to be 0.591 nm for 1% change of surrounding RI. The proposed sensor structure features simple structure, low cost, easy fabrication, and high sensitivity. PMID:22666052

  15. Gas Sensors Based on Single-Arm Waveguide Interferometers

    NASA Technical Reports Server (NTRS)

    Sarkisov, Sergey; Curley, Michael; Diggs, Darnell; Adamovsky, Grigory

    1998-01-01

    Various optical technologies can be implemented in chemical sensing. Sensitive, rugged, and compact systems will be more likely built using interferometric waveguide sensors. Currently existing sensors comprise dual-arm systems with external reference arm, dual-arm devices with internal reference arm such as integrated Mach-Zehnder interferometer, and single-arm systems which employ the interference between different waveguide modes. These latter ones are the most compact and rugged but still sensitive enough to monitor volatile pollutants such as NH3 coming out of industrial refrigerators and fertilizer plants and stocks, NO, NO2, SO2, emitted by industrial burning processes. Single-arm devices in planar waveguide configuration most frequently use two orthogonally polarized modes TE (sub i) and TM (sub i) of the same order i. Sensing effect is based on the difference in propagation conditions for the modes caused by the environment. However, dual-mode single-order interferometers still have relatively low sensitivity with respect to the environment related changes in the waveguide core because of small difference between propagation constants of TE (sub i) and TM (sub i) modes of the same order. Substantial sensitivity improvement without significant complication can be achieved for planar waveguide interferometers using modes of different orders with much greater difference between propagation constants.

  16. Fabrication of metallic single electron transistors featuring plasma enhanced atomic layer deposition of tunnel barriers

    NASA Astrophysics Data System (ADS)

    Karbasian, Golnaz

    The continuing increase of the device density in integrated circuits (ICs) gives rise to the high level of power that is dissipated per unit area and consequently a high temperature in the circuits. Since temperature affects the performance and reliability of the circuits, minimization of the energy consumption in logic devices is now the center of attention. According to the International Technology Roadmaps for Semiconductors (ITRS), single electron transistors (SETs) hold the promise of achieving the lowest power of any known logic device, as low as 1x10-18 J per switching event. Moreover, SETs are the most sensitive electrometers to date, and are capable of detecting a fraction of an electron charge. Despite their low power consumption and high sensitivity for charge detection, room temperature operation of these devices is quite challenging mainly due to lithographical constraints in fabricating structures with the required dimensions of less than 10 nm. Silicon based SETs have been reported to operate at room temperature. However, they all suffer from significant variation in batch-to-batch performance, low fabrication yield, and temperature-dependent tunnel barrier height. In this project, we explored the fabrication of SETs featuring metal-insulator-metal (MIM) tunnel junctions. While Si-based SETs suffer from undesirable effect of dopants that result in irregularities in the device behavior, in metal-based SETs the device components (tunnel barrier, island, and the leads) are well-defined. Therefore, metal SETs are potentially more predictable in behavior, making them easier to incorporate into circuits, and easier to check against theoretical models. Here, the proposed fabrication method takes advantage of unique properties of chemical mechanical polishing (CMP) and plasma enhanced atomic layer deposition (PEALD). Chemical mechanical polishing provides a path for tuning the dimensions of the tunnel junctions, surpassing the limits imposed by electron beam

  17. Composite versus single transportable carbohydrate solution enhances race and laboratory cycling performance.

    PubMed

    Rowlands, David S; Swift, Marilla; Ros, Marjolein; Green, Jackson G

    2012-06-01

    When ingested at high rates (1.8-2.4 g·min(-1)) in concentrated solutions, carbohydrates absorbed by multiple (e.g., fructose and glucose) vs. single intestinal transporters can increase exogenous carbohydrate oxidation and endurance performance, but their effect when ingested at lower, more realistic, rates during intermittent high-intensity endurance competition and trials is unknown. Trained cyclists participated in two independent randomized crossover investigations comprising mountain-bike races (average 141 min; n = 10) and laboratory trials (94-min high-intensity intervals followed by 10 maximal sprints; n = 16). Solutions ingested during exercise contained electrolytes and fructose + maltodextrin or glucose + maltodextrin in 1:2 ratio ingested, on average, at 1.2 g carbohydrate·kg(-1)·h(-1). Exertion, muscle fatigue, and gastrointestinal discomfort were recorded. Data were analysed using mixed models with gastrointestinal discomfort as a mechanism covariate; inferences were made against substantiveness thresholds (1.2% for performance) and standardized difference. The fructose-maltodextrin solution substantially reduced race time (-1.8%; 90% confidence interval = ±1.8%) and abdominal cramps (-8.1 on a 0-100 scale; ±6.6). After accounting for gastrointestinal discomfort, the effect of the fructose-maltodextrin solution on lap time was reduced (-1.1%; ±2.4%), suggesting that gastrointestinal discomfort explained part of the effect of fructose-maltodextrin on performance. In the laboratory, mean sprint power was enhanced (1.4%; ±0.8%) with fructose-maltodextrin, but the effect on peak power was unclear (0.7%; ±1.5%). Adjusting out gastrointestinal discomfort augmented the fructose-maltodextrin effect on mean (2.6%; ±1.9%) and peak (2.5%; ±3.0%) power. Ingestion of multiple transportable vs. single transportable carbohydrates enhanced mountain-bike race and high-intensity laboratory cycling performance, with inconsistent but not irreconcilable effects

  18. STEP: spatiotemporal enhancement pattern for MR-based breast tumor diagnosis.

    PubMed

    Zheng, Yuanjie; Englander, Sarah; Baloch, Sajjad; Zacharaki, Evangelia I; Fan, Yong; Schnall, Mitchell D; Shen, Dinggang

    2009-07-01

    The authors propose a spatiotemporal enhancement pattern (STEP) for comprehensive characterization of breast tumors in contrast-enhanced MR images. By viewing serial contrast-enhanced MR images as a single spatiotemporal image, they formulate the STEP as a combination of (1) dynamic enhancement and architectural features of a tumor, and (2) the spatial variations of pixelwise temporal enhancements. Although the latter has been widely used by radiologists for diagnostic purposes, it has rarely been employed for computer-aided diagnosis. This article presents two major contributions. First, the STEP features are introduced to capture temporal enhancement and its spatial variations. This is essentially carried out through the Fourier transformation and pharmacokinetic modeling of various temporal enhancement features, followed by the calculation of moment invariants and Gabor texture features. Second, for effectively extracting the STEP features from tumors, we develop a graph-cut based segmentation algorithm that aims at refining coarse manual segmentations of tumors. The STEP features are assessed through their diagnostic performance for differentiating between benign and malignant tumors using a linear classifier (along with a simple ranking-based feature selection) in a leave-one-out cross-validation setting. The experimental results for the proposed features exhibit superior performance, when compared to the existing approaches, with the area under the ROC curve approaching 0.97.

  19. Alu-associated enhancement of single nucleotide polymorphisms in the human genome.

    PubMed

    Ng, Siu-Kin; Xue, Hong

    2006-03-01

    Identifying features shaping the architecture of sequence variations is important for understanding genome evolution and mapping disease loci. In this study, high-resolution scanning of Alu-centered alignments of the human genome sequences has revealed a striking elevation of the frequency of single nucleotide polymorphisms (SNP) in the body and tail of Alu sequences compared to flanking regions. This enhancement in SNP density is evident for all twenty-four chromosomes, and in both the Alu-body and Alu-tail, which together may be referred to as the Alu-SNPs. Reduced levels of Alu-SNPs in the sex chromosomes, especially in the non-recombining NRY region of the Y chromosome, are consistent with recombination events playing an important role in the enhancement. The Alu elements are unstable recombination-mutation hotspots in the human genome, and it is suggested that the Alu-SNPs represent a key manifestation of this instability. Variations in Alu-SNPs among the HapMap populations of northern and western European ancestry (CEU), Han Chinese from Beijing (CHB), Japanese from Tokyo (JPT), and Yoruba from Ibadan, Nigeria (YRI) indicate that the Alu-SNPs provide useful sequence markers, in addition to the Alu-insertion polymorphisms themselves, for the delineation of human genome evolution. That Alu-SNP levels are highest in the youngest Alu-Y, intermediate in the Alu-S of intermediate age, and lowest in the oldest Alu-J is consistent with the occurrence of not only genetic drift but also natural selection on the Alu-SNPs. Such evolutionary selection in turn suggests that Alu-SNPs might include potential sites of disease association, and therefore deserve detailed investigation. PMID:16380220

  20. Automatic system for single ion/single cell irradiation based on Cracow microprobe

    NASA Astrophysics Data System (ADS)

    Veselov, O.; Polak, W.; Lekki, J.; Stachura, Z.; Lebed, K.; Styczeń, J.; Ugenskiene, R.

    2006-05-01

    Recently, the Cracow ion microprobe has found its new application as a single ion hit facility (SIHF), allowing precise irradiations of living cells by a controlled number of ions. The instrument enables a broad field of research, such as survival studies, adaptive response investigations, bystander effect, inverse dose-rate effect, low-dose hypersensitivity, etc. This work presents principles of construction and operation of the SIHF based on the Cracow microprobe. We discuss some crucial features of optical, positioning, and blanking systems, including self-developed software responsible for semiautomatic cell recognition, for precise positioning of cells, and for controlling the irradiation process. We also show some tests carried out to determine the efficiency of the whole system and of its segments. In addition, we present results of the first irradiation measurements performed with living cells.

  1. Single sideband communications. Citations from the NTIS data base

    NASA Astrophysics Data System (ADS)

    Reed, W. E.

    1980-08-01

    Federally sponsored research on single sideband communication equipment and systems is presented. Reports on the design, development, and operation are cited. Studies on single sideband transmission, modulation, and single processing are included.

  2. Enhanced non-volatile resistive switching in suspended single-crystalline ZnO nanowire with controllable multiple states

    NASA Astrophysics Data System (ADS)

    Zhang, Rui; Pang, Wei; Zhang, Qing; Chen, Yan; Chen, Xuejiao; Feng, Zhihong; Yang, Jianhua; Zhang, Daihua

    2016-08-01

    Resistive switching nanostructures are a promising candidate for next-generation non-volatile memories. In this report, we investigate the switching behaviors of single-crystalline ZnO nanowires suspended in air. They exhibit significantly higher current density, lower switching voltage, and more pronounced multiple conductance states compared to nanowires in direct contact with substrate. We attribute the effect to enhanced Joule heating efficiency, reduced surface scattering, and more significantly, the positive feedback established between the current density and local temperature in the suspended nanowires. The proposed mechanism has been quantitatively examined by finite element simulations. We have also demonstrated an innovative approach to initiating the current–temperature mutual enhancement through illumination by ultraviolet light, which further confirmed our hypothesis and enabled even greater enhancement. Our work provides further insight into the resistive switching mechanism of single-crystalline one-dimensional nanostructures, and suggests an effective means of performance enhancement and device optimization.

  3. Enhanced non-volatile resistive switching in suspended single-crystalline ZnO nanowire with controllable multiple states

    NASA Astrophysics Data System (ADS)

    Zhang, Rui; Pang, Wei; Zhang, Qing; Chen, Yan; Chen, Xuejiao; Feng, Zhihong; Yang, Jianhua; Zhang, Daihua

    2016-08-01

    Resistive switching nanostructures are a promising candidate for next-generation non-volatile memories. In this report, we investigate the switching behaviors of single-crystalline ZnO nanowires suspended in air. They exhibit significantly higher current density, lower switching voltage, and more pronounced multiple conductance states compared to nanowires in direct contact with substrate. We attribute the effect to enhanced Joule heating efficiency, reduced surface scattering, and more significantly, the positive feedback established between the current density and local temperature in the suspended nanowires. The proposed mechanism has been quantitatively examined by finite element simulations. We have also demonstrated an innovative approach to initiating the current-temperature mutual enhancement through illumination by ultraviolet light, which further confirmed our hypothesis and enabled even greater enhancement. Our work provides further insight into the resistive switching mechanism of single-crystalline one-dimensional nanostructures, and suggests an effective means of performance enhancement and device optimization.

  4. Contrast enhancement via texture region based histogram equalization

    NASA Astrophysics Data System (ADS)

    Singh, Kuldeep; Vishwakarma, Dinesh K.; Singh Walia, Gurjit; Kapoor, Rajiv

    2016-08-01

    This paper presents two novel contrast enhancement approaches using texture regions-based histogram equalization (HE). In HE-based contrast enhancement methods, the enhanced image often contains undesirable artefacts because an excessive number of pixels in the non-textured areas heavily bias the histogram. The novel idea presented in this paper is to suppress the impact of pixels in non-textured areas and to exploit texture features for the computation of histogram in the process of HE. The first algorithm named as Dominant Orientation-based Texture Histogram Equalization (DOTHE), constructs the histogram of the image using only those image patches having dominant orientation. DOTHE categories image patches into smooth, dominant or non-dominant orientation patches by using the image variance and singular value decomposition algorithm and utilizes only dominant orientation patches in the process of HE. The second method termed as Edge-based Texture Histogram Equalization, calculates significant edges in the image and constructs the histogram using the grey levels present in the neighbourhood of edges. The cumulative density function of the histogram formed from texture features is mapped on the entire dynamic range of the input image to produce the contrast-enhanced image. Subjective as well as objective performance assessment of proposed methods is conducted and compared with other existing HE methods. The performance assessment in terms of visual quality, contrast improvement index, entropy and measure of enhancement reveals that the proposed methods outperform the existing HE methods.

  5. Single-molecular diodes based on opioid derivatives.

    PubMed

    Siqueira, M R S; Corrêa, S M; Gester, R M; Del Nero, J; Neto, A M J C

    2015-12-01

    We propose an efficient single-molecule rectifier based on a derivative of opioid. Electron transport properties are investigated within the non-equilibrium Green's function formalism combined with density functional theory. The analysis of the current-voltage characteristics indicates obvious diode-like behavior. While heroin presents rectification coefficient R>1, indicating preferential electronic current from electron-donating to electron-withdrawing, 3 and 6-acetylmorphine and morphine exhibit contrary behavior, R<1. Our calculations indicate that the simple inclusion of acetyl groups modulate a range of devices, which varies from simple rectifying to resonant-tunneling diodes. In particular, the rectification rations for heroin diodes show microampere electron current with a maximum of rectification (R=9.1) at very low bias voltage of ∼0.6 V and (R=14.3)∼1.8 V with resistance varying between 0.4 and 1.5 M Ω. Once most of the current single-molecule diodes usually rectifies in nanoampere, are not stable over 1.0 V and present electrical resistance around 10 M. Molecular devices based on opioid derivatives are promising in molecular electronics.

  6. Single-View Food Portion Estimation Based on Geometric Models

    PubMed Central

    Fang, Shaobo; Liu, Chang; Zhu, Fengqing; Delp, Edward J.; Boushey, Carol J.

    2016-01-01

    In this paper we present a food portion estimation technique based on a single-view food image used for the estimation of the amount of energy (in kilocalories) consumed at a meal. Unlike previous methods we have developed, the new technique is capable of estimating food portion without manual tuning of parameters. Although single-view 3D scene reconstruction is in general an ill-posed problem, the use of geometric models such as the shape of a container can help to partially recover 3D parameters of food items in the scene. Based on the estimated 3D parameters of each food item and a reference object in the scene, the volume of each food item in the image can be determined. The weight of each food can then be estimated using the density of the food item. We were able to achieve an error of less than 6% for energy estimation of an image of a meal assuming accurate segmentation and food classification. PMID:27672682

  7. Rapid sequencing of DNA based on single-molecule detection

    NASA Astrophysics Data System (ADS)

    Soper, Steven A.; Davis, Lloyd M.; Fairfield, Frederick R.; Hammond, Mark L.; Harger, Carol A.; Jett, James H.; Keller, Richard A.; Marrone, Babetta L.; Martin, John C.; Nutter, Harvey L.; Shera, E. Brooks; Simpson, Daniel J.

    1991-07-01

    Sequencing the human genome is a major undertaking considering the large number of nucleotides present in the genome and the slow methods currently available to perform the task. The authors have recently reported on a scheme to sequence DNA rapidly using a non-gel based technique. The concept is based upon the incorporation of fluorescently labeled nucleotides into a strand of DNA, isolation and manipulation of a labeled DNA fragment and the detection of single nucleotides using ultra-sensitive laser-induced fluorescence detection following their cleavage from the fragment. Detection of individual fluorophores in the liquid phase was accomplished with time-gated detection following pulsed-laser excitation. The photon bursts from individual rhodamine 6G (R6G) molecules travelling through a laser beam have been observed, as have bursts from single fluorescently modified nucleotides. Using two different biotinylated nucleotides as a model system for fluorescently labeled nucleotides, the authors have observed synthesis of the complementary copy of M13 bacteriophage. Work with fluorescently labeled nucleotides is underway. Individual molecules of DNA attached to a microbead have been observed and manipulated with an epifluorescence microscope.

  8. Rapid sequencing of DNA based on single molecule detection

    SciTech Connect

    Soper, S.A.; Davis, L.M.; Fairfield, F.R.; Hammond, M.L.; Harger, C.A.; Jett, J.H.; Keller, R.A.; Marrone, B.L.; Martin, J.C.; Nutter, H.L.; Shera, E.B.; Simpson, D.J.

    1991-01-01

    Sequencing the human genome is a major undertaking considering the large number of nucleotides present in the genome and the slow methods currently available to perform the task. We have recently reported on a scheme to sequence DNA rapidly using a non-gel based technique. The concept is based upon the incorporation of fluorescently labeled nucleotides into a strand of DNA, isolation and manipulation of a labeled DNA fragment and the detection of single nucleotides using ultra-sensitive laser-induced fluorescence detection following their cleavage from the fragment. Detection of individual fluorophores in the liquid phase was accomplished with time-gated detection following pulsed-laser excitation. The photon bursts from individual rhodamine 6G (R6G) molecules travelling through a laser beam have been observed as have bursts from single fluorescently modified nucleotides. Using two different biotinylated nucleotides as a model system for fluorescently labeled nucleotides, we have observed synthesis of the complementary copy of M13 bacteriophage. Work with fluorescently labeled nucleotides is underway. We have observed and manipulated individual molecules of DNA attached to a microbead with an epifluorescence microscope. 16 refs., 3 figs., 1 tab.

  9. Single-molecular diodes based on opioid derivatives.

    PubMed

    Siqueira, M R S; Corrêa, S M; Gester, R M; Del Nero, J; Neto, A M J C

    2015-12-01

    We propose an efficient single-molecule rectifier based on a derivative of opioid. Electron transport properties are investigated within the non-equilibrium Green's function formalism combined with density functional theory. The analysis of the current-voltage characteristics indicates obvious diode-like behavior. While heroin presents rectification coefficient R>1, indicating preferential electronic current from electron-donating to electron-withdrawing, 3 and 6-acetylmorphine and morphine exhibit contrary behavior, R<1. Our calculations indicate that the simple inclusion of acetyl groups modulate a range of devices, which varies from simple rectifying to resonant-tunneling diodes. In particular, the rectification rations for heroin diodes show microampere electron current with a maximum of rectification (R=9.1) at very low bias voltage of ∼0.6 V and (R=14.3)∼1.8 V with resistance varying between 0.4 and 1.5 M Ω. Once most of the current single-molecule diodes usually rectifies in nanoampere, are not stable over 1.0 V and present electrical resistance around 10 M. Molecular devices based on opioid derivatives are promising in molecular electronics. PMID:26613894

  10. Single-channel stereoscopic ophthalmology microscope based on TRD

    NASA Astrophysics Data System (ADS)

    Radfar, Edalat; Park, Jihoon; Lee, Sangyeob; Ha, Myungjin; Yu, Sungkon; Jang, Seulki; Jung, Byungjo

    2016-03-01

    A stereoscopic imaging modality was developed for the application of ophthalmology surgical microscopes. A previous study has already introduced a single-channel stereoscopic video imaging modality based on a transparent rotating deflector (SSVIM-TRD), in which two different view angles, image disparity, are generated by imaging through a transparent rotating deflector (TRD) mounted on a stepping motor and is placed in a lens system. In this case, the image disparity is a function of the refractive index and the rotation angle of TRD. Real-time single-channel stereoscopic ophthalmology microscope (SSOM) based on the TRD is improved by real-time controlling and programming, imaging speed, and illumination method. Image quality assessments were performed to investigate images quality and stability during the TRD operation. Results presented little significant difference in image quality in terms of stability of structural similarity (SSIM). A subjective analysis was performed with 15 blinded observers to evaluate the depth perception improvement and presented significant improvement in the depth perception capability. Along with all evaluation results, preliminary results of rabbit eye imaging presented that the SSOM could be utilized as an ophthalmic operating microscopes to overcome some of the limitations of conventional ones.

  11. Enhanced piezoelectric properties of vertically aligned single-crystalline NKN nano-rod arrays.

    PubMed

    Kang, Min-Gyu; Oh, Seung-Min; Jung, Woo-Suk; Moon, Hi Gyu; Baek, Seung-Hyub; Nahm, Sahn; Yoon, Seok-Jin; Kang, Chong-Yun

    2015-05-08

    Piezoelectric materials capable of converting between mechanical and electrical energy have a great range of potential applications in micro- and nano-scale smart devices; however, their performance tends to be greatly degraded when reduced to a thin film due to the large clamping force by the substrate and surrounding materials. Herein, we report an effective method for synthesizing isolated piezoelectric nano-materials as means to relax the clamping force and recover original piezoelectric properties of the materials. Using this, environmentally friendly single-crystalline NaxK1-xNbO3 (NKN) piezoelectric nano-rod arrays were successfully synthesized by conventional pulsed-laser deposition and demonstrated to have a remarkably enhanced piezoelectric performance. The shape of the nano-structure was also found to be easily manipulated by varying the energy conditions of the physical vapor. We anticipate that this work will provide a way to produce piezoelectric micro- and nano-devices suitable for practical application, and in doing so, open a new path for the development of complex metal-oxide nano-structures.

  12. Evaluation of a single-session brief motivational enhancement intervention for partner abusive men.

    PubMed

    Crane, Cory A; Eckhardt, Christopher I

    2013-04-01

    The current study evaluated the efficacy of a single-session brief motivational enhancement (BME) interview to increase treatment compliance and reduce recidivism rates in a sample of 82 recently adjudicated male perpetrators of intimate partner violence (IPV). Batterer intervention program attendance and completion as well as re-arrest records served as the primary outcome measures and were collected 6 months post-adjudication. Results indicated that BME was associated with increases in session attendance and treatment compliance. BME was not directly associated with reductions in recidivism. The relationship between BME and treatment compliance was moderated by readiness to change such that BME participants with low readiness to change attended more sessions and were more likely to be in compliance with the terms of a treatment than control participants with low readiness, while participants with high readiness attended sessions equally, regardless of study condition. Results indicate that outcomes may be improved through treatment efforts that consider individual differences, such as one's readiness to change, in planning interventions for IPV perpetrators.

  13. Enhanced piezoelectric properties of vertically aligned single-crystalline NKN nano-rod arrays

    PubMed Central

    Kang, Min-Gyu; Oh, Seung-Min; Jung, Woo-Suk; Gyu Moon, Hi; Baek, Seung-Hyub; Nahm, Sahn; Yoon, Seok-Jin; Kang, Chong-Yun

    2015-01-01

    Piezoelectric materials capable of converting between mechanical and electrical energy have a great range of potential applications in micro- and nano-scale smart devices; however, their performance tends to be greatly degraded when reduced to a thin film due to the large clamping force by the substrate and surrounding materials. Herein, we report an effective method for synthesizing isolated piezoelectric nano-materials as means to relax the clamping force and recover original piezoelectric properties of the materials. Using this, environmentally friendly single-crystalline NaxK1-xNbO3 (NKN) piezoelectric nano-rod arrays were successfully synthesized by conventional pulsed-laser deposition and demonstrated to have a remarkably enhanced piezoelectric performance. The shape of the nano-structure was also found to be easily manipulated by varying the energy conditions of the physical vapor. We anticipate that this work will provide a way to produce piezoelectric micro- and nano-devices suitable for practical application, and in doing so, open a new path for the development of complex metal-oxide nano-structures. PMID:25955763

  14. Radiation-Induced Helium Nanobubbles Enhance Ductility in Submicron-Sized Single-Crystalline Copper.

    PubMed

    Ding, Ming-Shuai; Du, Jun-Ping; Wan, Liang; Ogata, Shigenobu; Tian, Lin; Ma, Evan; Han, Wei-Zhong; Li, Ju; Shan, Zhi-Wei

    2016-07-13

    The workability and ductility of metals usually degrade with exposure to irradiation, hence the phrase "radiation damage". Here, we found that helium (He) radiation can actually enhance the room-temperature deformability of submicron-sized copper. In particular, Cu single crystals with diameter of 100-300 nm and containing numerous pressurized sub-10 nm He bubbles become stronger, more stable in plastic flow and ductile in tension, compared to fully dense samples of the same dimensions that tend to display plastic instability (strain bursts). The sub-10 nm He bubbles are seen to be dislocation sources as well as shearable obstacles, which promote dislocation storage and reduce dislocation mean free path, thus contributing to more homogeneous and stable plasticity. Failure happens abruptly only after significant bubble coalescence. The current findings can be explained in light of Weibull statistics of failure and the beneficial effects of bubbles on plasticity. These results shed light on plasticity and damage developments in metals and could open new avenues for making mechanically robust nano- and microstructures by ion beam processing and He bubble engineering.

  15. Biological nitrogen removal with enhanced phosphate uptake in a sequencing batch reactor using single sludge system.

    PubMed

    Lee, D S; Jeon, C O; Park, J M

    2001-11-01

    Simultaneous biological phosphorus and nitrogen removal with enhanced anoxic phosphate uptake was investigated in an anaerobic-aerobic-anoxic-aerobic sequencing batch reactor ((AO)2 SBR). Significant amounts of phosphorus-accumulation organisms (PAOs) capable of denitrification could be accumulated in a single sludge system coexisting with nitrifiers. The ratio of the anoxic phosphate uptake to the aerobic phosphate uptake capacity was increased from 11% to 64% by introducing an anoxic phase in an anaerobic aerobic SBR. The (AO)2 SBR system showed stable phosphorus and nitrogen removal performance. Average removal efficiencies of TOC, total nitrogen, and phosphorus were 92%, 88%, and 100%, respectively. It was found that nitrite (up to 10 mg NO2(-)-N/l) was not detrimental to the anoxic phosphate uptake and could serve as an electron acceptor like nitrate. In fact, the phosphate uptake rate was even faster in the presence of nitrite as an electron acceptor compared to the presence of nitrate. It was found that on-line sensor values of pH, ORP, and DO were somehow related with the dynamic behaviours of nutrient concentrations (NH4+, NO3-, and PO4(3-)) in the SBR. These on-line sensor values were used as real-time control parameters to adjust the duration of each operational phase in the (AO)2 SBR. The real-time controlled SBR exhibited better performance in the removal of phosphorus and nitrogen than the SBR with fixed-time operation. PMID:12230180

  16. Multiplex CRISPR/Cas9-based genome engineering from a single lentiviral vector.

    PubMed

    Kabadi, Ami M; Ousterout, David G; Hilton, Isaac B; Gersbach, Charles A

    2014-10-29

    Engineered DNA-binding proteins that manipulate the human genome and transcriptome have enabled rapid advances in biomedical research. In particular, the RNA-guided CRISPR/Cas9 system has recently been engineered to create site-specific double-strand breaks for genome editing or to direct targeted transcriptional regulation. A unique capability of the CRISPR/Cas9 system is multiplex genome engineering by delivering a single Cas9 enzyme and two or more single guide RNAs (sgRNAs) targeted to distinct genomic sites. This approach can be used to simultaneously create multiple DNA breaks or to target multiple transcriptional activators to a single promoter for synergistic enhancement of gene induction. To address the need for uniform and sustained delivery of multiplex CRISPR/Cas9-based genome engineering tools, we developed a single lentiviral system to express a Cas9 variant, a reporter gene and up to four sgRNAs from independent RNA polymerase III promoters that are incorporated into the vector by a convenient Golden Gate cloning method. Each sgRNA is efficiently expressed and can mediate multiplex gene editing and sustained transcriptional activation in immortalized and primary human cells. This delivery system will be significant to enabling the potential of CRISPR/Cas9-based multiplex genome engineering in diverse cell types.

  17. Multiplex CRISPR/Cas9-based genome engineering from a single lentiviral vector.

    PubMed

    Kabadi, Ami M; Ousterout, David G; Hilton, Isaac B; Gersbach, Charles A

    2014-10-29

    Engineered DNA-binding proteins that manipulate the human genome and transcriptome have enabled rapid advances in biomedical research. In particular, the RNA-guided CRISPR/Cas9 system has recently been engineered to create site-specific double-strand breaks for genome editing or to direct targeted transcriptional regulation. A unique capability of the CRISPR/Cas9 system is multiplex genome engineering by delivering a single Cas9 enzyme and two or more single guide RNAs (sgRNAs) targeted to distinct genomic sites. This approach can be used to simultaneously create multiple DNA breaks or to target multiple transcriptional activators to a single promoter for synergistic enhancement of gene induction. To address the need for uniform and sustained delivery of multiplex CRISPR/Cas9-based genome engineering tools, we developed a single lentiviral system to express a Cas9 variant, a reporter gene and up to four sgRNAs from independent RNA polymerase III promoters that are incorporated into the vector by a convenient Golden Gate cloning method. Each sgRNA is efficiently expressed and can mediate multiplex gene editing and sustained transcriptional activation in immortalized and primary human cells. This delivery system will be significant to enabling the potential of CRISPR/Cas9-based multiplex genome engineering in diverse cell types. PMID:25122746

  18. Single Crystal DMs for Space-Based Observatories

    NASA Astrophysics Data System (ADS)

    Bierden, Paul

    We propose to demonstrate the feasibility of a new manufacturing process for large aperture, high-actuator count microelectromechanical deformable mirrors (MEMS-DMs). These DMs are designed to fill a critical technology gap in NASA s plan for high- contrast space-based exoplanet observatories. We will manufacture a prototype DM with a continuous mirror facesheet, having an active aperture of 50mm diameter, supported by 2040 electrostatic actuators (50 across the diameter of the active aperture), spaced at a pitch of 1mm. The DM will be manufactured using silicon microfabrication tools. The strategic motivation for the proposed project is to advance MEMS DMs as an enabling technology in NASA s rapidly emerging program for extrasolar planet exploration. That goal is supported by an Astro2010 white paper on Technologies for Direct Optical Imaging of Exoplanets, which concluded that DMs are a critical component for all proposed internal coronagraph instrument concepts. That white paper pointed to great strides made by DM developers in the past decade, and acknowledged the components made by Boston Micromachines Corporation to be the most notable MEMS-based technology option. The principal manufacturing innovation in this project will be assembly of the DM through fusion bonding of three separate single crystal silicon wafers comprising the device s substrate, actuator array, and facesheet. The most significant challenge of this project will be to develop processes that allow reliable fusion bonds between multiple compliant silicon layers while yielding an optically flat surface and a robust electromechanical system. The compliance of the DM, which is required for its electromechanical function, will make it challenging to achieve the intimate, planar contact that is generally needed for success in fusion bonding. The manufacturing approach will use photolithography and reactive ion etching to pattern structural layers. Three wafer-scale devices will be patterned and

  19. Correlation dynamics and enhanced signals for the identification of serial biomolecules and DNA bases

    NASA Astrophysics Data System (ADS)

    Ahmed, Towfiq; Haraldsen, Jason T.; Rehr, John J.; Di Ventra, Massimiliano; Schuller, Ivan; Balatsky, Alexander V.

    2014-03-01

    Nanopore-based sequencing has demonstrated a significant potential for the development of fast, accurate, and cost-efficient fingerprinting techniques for next generation molecular detection and sequencing. We propose a specific multilayered graphene-based nanopore device architecture for the recognition of single biomolecules. Molecular detection and analysis can be accomplished through the detection of transverse currents as the molecule or DNA base translocates through the nanopore. To increase the overall signal-to-noise ratio and the accuracy, we implement a new ‘multi-point cross-correlation’ technique for identification of DNA bases or other molecules on the single molecular level. We demonstrate that the cross-correlations between each nanopore will greatly enhance the transverse current signal for each molecule. We implement first-principles transport calculations for DNA bases surveyed across a multilayered graphene nanopore system to illustrate the advantages of the proposed geometry. A time-series analysis of the cross-correlation functions illustrates the potential of this method for enhancing the signal-to-noise ratio. This work constitutes a significant step forward in facilitating fingerprinting of single biomolecules using solid state technology.

  20. Efficient single photon source based on μ-fibre-coupled tunable microcavity

    PubMed Central

    Lee, Chang-Min; Lim, Hee-Jin; Schneider, Christian; Maier, Sebastian; Höfling, Sven; Kamp, Martin; Lee, Yong-Hee

    2015-01-01

    Efficient and fast on-demand single photon sources have been sought after as critical components of quantum information science. We report an efficient and tunable single photon source based on an InAs quantum dot (QD) embedded in a photonic crystal cavity coupled with a highly curved μ-fibre. Exploiting evanescent coupling between the μ-fibre and the cavity, a high collection efficiency of 23% and Purcell-enhanced spontaneous emissions are observed. In our scheme, the spectral position of a resonance can be tuned by as much as 1.5 nm by adjusting the contact position of the μ-fibre, which increases the spectral coupling probability between the QD and the cavity mode. Taking advantage of the high photon count rate and the tunability, the collection efficiencies and the decay rates are systematically investigated as a function of the QD–cavity detuning. PMID:26391607

  1. ENHANCED HYDROGEN PRODUCTION INTEGRATED WITH CO2 SEPARATION IN A SINGLE-STAGE REACTOR

    SciTech Connect

    Himanshu Gupta; Mahesh Iyer; Bartev Sakadjian; Liang-Shih Fan

    2005-04-01

    Hydrogen production by the water gas shift reaction (WGSR) is equilibrium limited due to thermodynamic constrains. However, this can be overcome by continuously removing the product CO{sub 2}, thereby driving the WGSR in the forward direction to enhance hydrogen production. This project aims at using a high reactivity, mesoporous calcium based sorbent (PCC-CaO) for removing CO{sub 2} using reactive separation scheme. Preliminary results have shown that PCC-CaO dominates in its performance over naturally occurring limestone towards enhanced hydrogen production. However, maintenance of high reactivity of the sorbent over several reaction-regeneration cycles warrants effective regeneration methods. We have identified sub-atmospheric calcination (vacuum) as vital regeneration technique that helps preserve the sorbent morphology. Sub-atmospheric calcination studies reveal the significance of vacuum level, diluent gas flow rate, thermal properties of diluent gas, and sorbent loading on the kinetics of calcination and the morphology of the resultant CaO sorbent. Steam, which can be easily separated from CO{sub 2}, has been envisioned as a potential diluent gas due to its better thermal properties resulting in effective heat transfer. A novel multi-fixed bed reactor was designed which isolates the catalyst bed from the sorbent bed during the calcination step. This should prevent any potential catalyst deactivation due to oxidation by CO{sub 2} during the regeneration phase.

  2. Single-step, high yield synthesis of gold nanoworms and their surface enhanced Raman scattering properties

    NASA Astrophysics Data System (ADS)

    Ahmed, Waqqar; van Ruitenbeek, Jan M.

    Rod-shaped gold nanoparticles have attracted enormous attention owing to their interesting optical properties arising from the surface plasmon resonances. Slight deviation from the rod morphology can markedly change the optical properties. For-example, worm-shaped gold nanoparticles can have more than two plasmon peaks. Furthermore, they show much higher local field enhancements as compared to their rod-shaped counterparts. We have devised a simple seedless, high-yield protocol for the synthesis of gold nanoworms (NWs). NWs were grown simply by reducing HAuCl4 with ascorbic acid in a high pH reaction medium, and in the presence of growth directional agents, cetyltrimethylammonium bromide and AgNO3. In contrast to the seed-mediated growth of gold nanorods where a seed grows into a rod, NWs grow by oriental attachment of nanoparticles. By varying different reaction parameters we were able to control the length of NWs from a few nanometers to micrometers. Furthermore, the aspect ratio can also be tuned over a wide range. Gold NWs show excellent surface enhanced Raman scattering (SERS) properties. Ultra-low concentrations of various target molecules were detected using NWs based SERS substrates.

  3. A Laplacian-based MMSE estimator for speech enhancement

    PubMed Central

    Chen, Bin; Loizou, Philipos C.

    2007-01-01

    This paper focuses on optimal estimators of the magnitude spectrum for speech enhancement. We present an analytical solution for estimating in the MMSE sense the magnitude spectrum when the clean speech DFT coefficients are modeled by a Laplacian distribution and the noise DFT coefficients are modeled by a Gaussian distribution. Furthermore, we derive the MMSE estimator under speech presence uncertainty and a Laplacian statistical model. Results indicated that the Laplacian-based MMSE estimator yielded less residual noise in the enhanced speech than the traditional Gaussian-based MMSE estimator. Overall, the present study demonstrates that the assumed distribution of the DFT coefficients can have a significant effect on the quality of the enhanced speech. PMID:18037977

  4. Double Layer Charging for Conductivity Enhancement of Pure Metallic and Semiconducting Single Wall Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Mayo, Nathanael; Kuznetsov, Alexander; Zakhidov, Anvar

    2011-03-01

    Injecting high electronic charge densities can profoundly change the optical, electrical, and magnetic properties of materials. Evidence suggests a possibility of significantly improving conductivity of carbon nanotubes through double layer charge injection. Double layer charge injection can prove to be a powerful method when applied to carbon nanotubes because of theirs high surface area and chemical stability. Investigation has commenced on the effect of charging on various types of carbon nanotubes, specifically 99% purified single wall semiconducting and single wall metallic tubes. An electrical double layer is electrochemically introduced upon a sheet of carbon nanotubes via application of potential (up to +/- 5 volts) to a sample immersed in ionic-liquid-based electrolyte. Resistance of carbon nanotube as a function of applied charging voltage is recorded to determine the effects of charge injection. Results show that the electrical double layer considerably reduces the resistance across both samples. ESR/LFMA studies combined with low temperature magnetic and transport measurements are conducted to search for charge injection induced superconductivity in carbon nanotubes. Supported by AFOSR grant FA 9550-09-1-0384.

  5. Nanosensors based on functionalized nanoparticles and surface enhanced raman scattering

    DOEpatents

    Talley, Chad E.; Huser, Thomas R.; Hollars, Christopher W.; Lane, Stephen M.; Satcher, Jr., Joe H.; Hart, Bradley R.; Laurence, Ted A.

    2007-11-27

    Surface-Enhanced Raman Spectroscopy (SERS) is a vibrational spectroscopic technique that utilizes metal surfaces to provide enhanced signals of several orders of magnitude. When molecules of interest are attached to designed metal nanoparticles, a SERS signal is attainable with single molecule detection limits. This provides an ultrasensitive means of detecting the presence of molecules. By using selective chemistries, metal nanoparticles can be functionalized to provide a unique signal upon analyte binding. Moreover, by using measurement techniques, such as, ratiometric received SERS spectra, such metal nanoparticles can be used to monitor dynamic processes in addition to static binding events. Accordingly, such nanoparticles can be used as nanosensors for a wide range of chemicals in fluid, gaseous and solid form, environmental sensors for pH, ion concentration, temperature, etc., and biological sensors for proteins, DNA, RNA, etc.

  6. Inferring Single Neuron Properties in Conductance Based Balanced Networks

    PubMed Central

    Pool, Román Rossi; Mato, Germán

    2011-01-01

    Balanced states in large networks are a usual hypothesis for explaining the variability of neural activity in cortical systems. In this regime the statistics of the inputs is characterized by static and dynamic fluctuations. The dynamic fluctuations have a Gaussian distribution. Such statistics allows to use reverse correlation methods, by recording synaptic inputs and the spike trains of ongoing spontaneous activity without any additional input. By using this method, properties of the single neuron dynamics that are masked by the balanced state can be quantified. To show the feasibility of this approach we apply it to large networks of conductance based neurons. The networks are classified as Type I or Type II according to the bifurcations which neurons of the different populations undergo near the firing onset. We also analyze mixed networks, in which each population has a mixture of different neuronal types. We determine under which conditions the intrinsic noise generated by the network can be used to apply reverse correlation methods. We find that under realistic conditions we can ascertain with low error the types of neurons present in the network. We also find that data from neurons with similar firing rates can be combined to perform covariance analysis. We compare the results of these methods (that do not requite any external input) to the standard procedure (that requires the injection of Gaussian noise into a single neuron). We find a good agreement between the two procedures. PMID:22016730

  7. Chip Based Single Cell Analysis for Nanotoxicity Assessment

    PubMed Central

    Shah, Pratikkumar; Kaushik, Ajeet; Zhu, Xuena; Zhang, Chengxiao; Li, Chen-Zhong

    2014-01-01

    Nanomaterials, because of their tunable properties and performances, have been utilized extensively in everyday life related consumable products and technology. On exposure, beyond physiological range, nanomaterials cause health risks via affecting the function of organisms, genomic systems, and even central nervous system. Thus, new analytical approaches for nanotoxicity assessment to verify the feasibility of nanomaterials for future use are in demand. The conventional analytical techniques, such as spectrophotometric assay-based techniques usually require a lengthy and time-consuming process and many times produces false positives, and many times cannot be implemented at a single cell level measurement for studying cell behavior without interference of their surrounding environment. Hence, there is demand of a precise, accurate, sensitive assessment for toxicity using single cell. Recently, due to advantages of automation of fluids and minimization of human error, the integration of cell-on-a-chip (CoC) with microfluidic system is in practice for nanotoxicity assessments. This review explains nanotoxicity and assessment approaches with advantages/limitations and new approaches to overcome the confines of traditional techniques. Recent advances in nanotoxicity assessment using CoC integrated with microfluidic system are also discussed in this review, which may be of use for nanotoxicity assessment and diagnostics. PMID:24567949

  8. Enhanced Heat Stability of α-Chymotrypsin through Single-Enzyme Confinement in Attoliter Liposomes.

    PubMed

    Yoshimoto, Makoto; Yamada, Jun; Baba, Misaki; Walde, Peter

    2016-07-01

    The entrapment of α-chymotrypsin (α-CT) within 70-140 nm liposomes formed from POPC (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine) leads to an unexpected and remarkable increase in the thermal stability of the enzyme. This finding is based on the observation that heating aqueous suspensions of α-CT-containing POPC liposomes to 80 °C for 30 minutes resulted in partial enzyme inactivation, whereas the same treatment of aqueous solutions of free α-CT inactivated the enzyme completely. The stabilizing effect of enzyme confinement in the attoliter volumes of the liposomes was found to increase with decreasing numbers of α-CT molecules per liposome. Single-enzyme confinement was particularly effective, as intermolecular interactions between heat-denatured α-CT molecules (causing irreversible inactivation) are not possible. PMID:27124158

  9. Photoluminescence Enhancement in CdSe/ZnS–DNA linked–Au Nanoparticle Heterodimers Probed by Single Molecule Spectroscopy

    SciTech Connect

    Cotlet, M.; Maye, M.M.; Gang, O.

    2010-07-26

    Photoluminescence enhancement of up to 20 fold is demonstrated at the single molecule level for heterodimers composed of a core/shell CdSe/ZnS semiconductive quantum dot and a gold nanoparticle of 60 nm size separated by a 32 nm-long dsDNA linker when employing optical excitation at wavelengths near the surface plasmon resonance of the gold nanoparticle.

  10. Anisotropy barrier enhancement via ligand substitution in tetranuclear {Co(III)2Ln(III)2} single molecule magnets.

    PubMed

    Langley, Stuart K; Chilton, Nicholas F; Moubaraki, Boujemaa; Murray, Keith S

    2013-08-11

    The replacement of coordinated acetylacetonate for nitrate around a Dy(III) ion results in the enhancement of the single molecule magnet properties of a {Co(III)2Dy(III)2} complex, resulting in a large thermal energy barrier and reduced quantum tunnelling at low temperatures. The analogous Tb(III) complex displays field induced SMM behaviour.

  11. A Microfluidic-based Hydrodynamic Trap for Single Particles

    PubMed Central

    Johnson-Chavarria, Eric M.; Tanyeri, Melikhan; Schroeder, Charles M.

    2011-01-01

    The ability to confine and manipulate single particles in free solution is a key enabling technology for fundamental and applied science. Methods for particle trapping based on optical, magnetic, electrokinetic, and acoustic techniques have led to major advancements in physics and biology ranging from the molecular to cellular level. In this article, we introduce a new microfluidic-based technique for particle trapping and manipulation based solely on hydrodynamic fluid flow. Using this method, we demonstrate trapping of micro- and nano-scale particles in aqueous solutions for long time scales. The hydrodynamic trap consists of an integrated microfluidic device with a cross-slot channel geometry where two opposing laminar streams converge, thereby generating a planar extensional flow with a fluid stagnation point (zero-velocity point). In this device, particles are confined at the trap center by active control of the flow field to maintain particle position at the fluid stagnation point. In this manner, particles are effectively trapped in free solution using a feedback control algorithm implemented with a custom-built LabVIEW code. The control algorithm consists of image acquisition for a particle in the microfluidic device, followed by particle tracking, determination of particle centroid position, and active adjustment of fluid flow by regulating the pressure applied to an on-chip pneumatic valve using a pressure regulator. In this way, the on-chip dynamic metering valve functions to regulate the relative flow rates in the outlet channels, thereby enabling fine-scale control of stagnation point position and particle trapping. The microfluidic-based hydrodynamic trap exhibits several advantages as a method for particle trapping. Hydrodynamic trapping is possible for any arbitrary particle without specific requirements on the physical or chemical properties of the trapped object. In addition, hydrodynamic trapping enables confinement of a "single" target object in

  12. Optimum wavelet based masking for the contrast enhancement of medical images using enhanced cuckoo search algorithm.

    PubMed

    Daniel, Ebenezer; Anitha, J

    2016-04-01

    Unsharp masking techniques are a prominent approach in contrast enhancement. Generalized masking formulation has static scale value selection, which limits the gain of contrast. In this paper, we propose an Optimum Wavelet Based Masking (OWBM) using Enhanced Cuckoo Search Algorithm (ECSA) for the contrast improvement of medical images. The ECSA can automatically adjust the ratio of nest rebuilding, using genetic operators such as adaptive crossover and mutation. First, the proposed contrast enhancement approach is validated quantitatively using Brain Web and MIAS database images. Later, the conventional nest rebuilding of cuckoo search optimization is modified using Adaptive Rebuilding of Worst Nests (ARWN). Experimental results are analyzed using various performance matrices, and our OWBM shows improved results as compared with other reported literature.

  13. Optimum wavelet based masking for the contrast enhancement of medical images using enhanced cuckoo search algorithm.

    PubMed

    Daniel, Ebenezer; Anitha, J

    2016-04-01

    Unsharp masking techniques are a prominent approach in contrast enhancement. Generalized masking formulation has static scale value selection, which limits the gain of contrast. In this paper, we propose an Optimum Wavelet Based Masking (OWBM) using Enhanced Cuckoo Search Algorithm (ECSA) for the contrast improvement of medical images. The ECSA can automatically adjust the ratio of nest rebuilding, using genetic operators such as adaptive crossover and mutation. First, the proposed contrast enhancement approach is validated quantitatively using Brain Web and MIAS database images. Later, the conventional nest rebuilding of cuckoo search optimization is modified using Adaptive Rebuilding of Worst Nests (ARWN). Experimental results are analyzed using various performance matrices, and our OWBM shows improved results as compared with other reported literature. PMID:26945462

  14. Color image enhancement based on HVS and MSRCR

    NASA Astrophysics Data System (ADS)

    Xue, Rong kun; Li, Yu feng

    2015-10-01

    Due to inclement weather caused frequently, such as clouds, fog , rain etc. The light intensity on the illuminated objects falls sharply, it make the scenes captured unclear, poor visual quality and low contrast degree. To improve the overall quality of these images, especially the bad illuminated images, the paper propose a new color image enhancement algorithm which is based on multi-scale Retinex theory with color recovering factor (MSRCR) and the human visual system (HVS). It can effectively solve the problem of the color balance of digital images by removing the influence of light and obtain component images reflected the reflex of the object surface, meanwhile, reduce the impact of non-artificial factors and overcome the Ringing effect and human interference. Through comparison and contrast among experiments, that combined evaluated parameters on enhancement image, such as variance, average gradient, sharpness and so forth with the traditional image enhancement methods, such as histogram enhancement, adaptive histogram enhancement, the MSRCR algorithm is proved to be effective in image contrast, detail enhancement and color fidelity, etc.

  15. Reproducible Ultrahigh SERS Enhancement in Single Deterministic Hotspots Using Nanosphere-Plane Antennas Under Radially Polarized Excitation.

    PubMed

    Long, Jing; Yi, Hui; Li, Hongquan; Lei, Zeyu; Yang, Tian

    2016-01-01

    Surface enhanced Raman scattering (SERS) in a nanometer size hotspot has empowered the investigation of chemical structures and dynamic behaviors of one and a few molecules. However, further advancement is hindered by lack of large enough yet reproducible enhancement in single deterministic hotspots. To resolve this problem, here we introduce a nanosphere-plane antenna under radially polarized laser excitation experiment, which provides an electromagnetic enhancement of 10(9~10) at the gap of each individual nanosphere-plane antenna and a root-mean-square error down to 10(0.08) between them. The experiment also reveals a nonlinear SERS behavior with less than one plasmon, which is also observed within a single hotspot. The unprecedented simultaneous achievement of ultrahigh enhancement and reproducibility in deterministic individual hotspots is attributed to the combination of a well-controlled hotspot geometry, the efficient coupling between vertical antenna and laser which produces orders of magnitude higher enhancement than previous excitation methods, and low power operation which is critical for high reproducibility. Our method opens a path for systematic studies on single and few molecule SERS and their surface chemistry in an in-situ and well-controlled manner. PMID:27621109

  16. Reproducible Ultrahigh SERS Enhancement in Single Deterministic Hotspots Using Nanosphere-Plane Antennas Under Radially Polarized Excitation.

    PubMed

    Long, Jing; Yi, Hui; Li, Hongquan; Lei, Zeyu; Yang, Tian

    2016-09-13

    Surface enhanced Raman scattering (SERS) in a nanometer size hotspot has empowered the investigation of chemical structures and dynamic behaviors of one and a few molecules. However, further advancement is hindered by lack of large enough yet reproducible enhancement in single deterministic hotspots. To resolve this problem, here we introduce a nanosphere-plane antenna under radially polarized laser excitation experiment, which provides an electromagnetic enhancement of 10(9~10) at the gap of each individual nanosphere-plane antenna and a root-mean-square error down to 10(0.08) between them. The experiment also reveals a nonlinear SERS behavior with less than one plasmon, which is also observed within a single hotspot. The unprecedented simultaneous achievement of ultrahigh enhancement and reproducibility in deterministic individual hotspots is attributed to the combination of a well-controlled hotspot geometry, the efficient coupling between vertical antenna and laser which produces orders of magnitude higher enhancement than previous excitation methods, and low power operation which is critical for high reproducibility. Our method opens a path for systematic studies on single and few molecule SERS and their surface chemistry in an in-situ and well-controlled manner.

  17. Reproducible Ultrahigh SERS Enhancement in Single Deterministic Hotspots Using Nanosphere-Plane Antennas Under Radially Polarized Excitation

    PubMed Central

    Long, Jing; Yi, Hui; Li, Hongquan; Lei, Zeyu; Yang, Tian

    2016-01-01

    Surface enhanced Raman scattering (SERS) in a nanometer size hotspot has empowered the investigation of chemical structures and dynamic behaviors of one and a few molecules. However, further advancement is hindered by lack of large enough yet reproducible enhancement in single deterministic hotspots. To resolve this problem, here we introduce a nanosphere-plane antenna under radially polarized laser excitation experiment, which provides an electromagnetic enhancement of 109~10 at the gap of each individual nanosphere-plane antenna and a root-mean-square error down to 100.08 between them. The experiment also reveals a nonlinear SERS behavior with less than one plasmon, which is also observed within a single hotspot. The unprecedented simultaneous achievement of ultrahigh enhancement and reproducibility in deterministic individual hotspots is attributed to the combination of a well-controlled hotspot geometry, the efficient coupling between vertical antenna and laser which produces orders of magnitude higher enhancement than previous excitation methods, and low power operation which is critical for high reproducibility. Our method opens a path for systematic studies on single and few molecule SERS and their surface chemistry in an in-situ and well-controlled manner. PMID:27621109

  18. Reproducible Ultrahigh SERS Enhancement in Single Deterministic Hotspots Using Nanosphere-Plane Antennas Under Radially Polarized Excitation

    NASA Astrophysics Data System (ADS)

    Long, Jing; Yi, Hui; Li, Hongquan; Lei, Zeyu; Yang, Tian

    2016-09-01

    Surface enhanced Raman scattering (SERS) in a nanometer size hotspot has empowered the investigation of chemical structures and dynamic behaviors of one and a few molecules. However, further advancement is hindered by lack of large enough yet reproducible enhancement in single deterministic hotspots. To resolve this problem, here we introduce a nanosphere-plane antenna under radially polarized laser excitation experiment, which provides an electromagnetic enhancement of 109~10 at the gap of each individual nanosphere-plane antenna and a root-mean-square error down to 100.08 between them. The experiment also reveals a nonlinear SERS behavior with less than one plasmon, which is also observed within a single hotspot. The unprecedented simultaneous achievement of ultrahigh enhancement and reproducibility in deterministic individual hotspots is attributed to the combination of a well-controlled hotspot geometry, the efficient coupling between vertical antenna and laser which produces orders of magnitude higher enhancement than previous excitation methods, and low power operation which is critical for high reproducibility. Our method opens a path for systematic studies on single and few molecule SERS and their surface chemistry in an in-situ and well-controlled manner.

  19. Optical sensor based on a single CdS nanobelt.

    PubMed

    Li, Lei; Yang, Shuming; Han, Feng; Wang, Liangjun; Zhang, Xiaotong; Jiang, Zhuangde; Pan, Anlian

    2014-04-23

    In this paper, an optical sensor based on a cadmium sulfide (CdS) nanobelt has been developed. The CdS nanobelt was synthesized by the vapor phase transportation (VPT) method. X-Ray Diffraction (XRD) and Transmission Electron Microscopy (TEM) results revealed that the nanobelt had a hexagonal wurtzite structure of CdS and presented good crystal quality. A single nanobelt Schottky contact optical sensor was fabricated by the electron beam lithography (EBL) technique, and the device current-voltage results showed back-to-back Schottky diode characteristics. The photosensitivity, dark current and the decay time of the sensor were 4 × 10⁴, 31 ms and 0.2 pA, respectively. The high photosensitivity and the short decay time were because of the exponential dependence of photocurrent on the number of the surface charges and the configuration of the back to back Schottky junctions.

  20. Algal-based, single-step treatment of urban wastewaters.

    PubMed

    Henkanatte-Gedera, S M; Selvaratnam, T; Caskan, N; Nirmalakhandan, N; Van Voorhies, W; Lammers, Peter J

    2015-08-01

    Currently, urban wastewaters (UWW) laden with organic carbon (BOD) and nutrients (ammoniacal nitrogen, N, and phosphates, P) are treated in multi-stage, energy-intensive process trains to meet the mandated discharge standards. This study presents a single-step process based on mixotrophic metabolism for simultaneous removal of carbon and nutrients from UWWs. The proposed system is designed specifically for hot, arid environments utilizing an acidophilic, thermotolerant algal species, Galdieria sulphuraria, and an enclosed photobioreactor to limit evaporation. Removal rates of BOD, N, and P recorded in this study (14.93, 7.23, and 1.38 mg L(-1) d(-1), respectively) are comparable to literature reports. These results confirm that the mixotrophic system can reduce the energy costs associated with oxygen supply in current UWW treatment systems, and has the potential to generate more energy-rich biomass for net energy extraction from UWW.

  1. Single Base-Resolution Methylome of the Dizygotic Sheep

    PubMed Central

    Liu, Bin; Su, Rui; Jiang, Yu; Wang, Wen; Dong, Yang

    2015-01-01

    Sheep is an important livestock in the world for meat, dairy and wool production. The third version of sheep reference genome has been recently assembled, but sheep DNA methylome has not been profiled yet. In this study, we report the comprehensive sheep methylome with 94.38% cytosine coverage at single base resolution by sequencing DNA samples from Longissimus dorsi of dizygotic Sunit sheep, which were bred in different habitats. We also compared methylomes between the twin sheep. DNA methylation status at genome-scale differentially methylated regions (DMRs), functional genomic regions and 248 DMR-containing genes were identified between the twin sheep. Gene ontology (GO) and KEGG annotations of these genes were performed to discover computationally predicted function. Lipid metabolism, sexual maturity and tumor-associated categories were observed to significantly enrich DMR-containing genes. These findings could be used to illustrate the relationship between phenotypic variations and gene methylation patterns. PMID:26536671

  2. Mars laser altimeter based on a single photon ranging technique

    NASA Technical Reports Server (NTRS)

    Prochazka, Ivan; Hamal, Karel; Sopko, B.; Pershin, S.

    1993-01-01

    The Mars 94/96 Mission will carry, among others things, the balloon probe experiment. The balloon with the scientific cargo in the gondola underneath will drift in the Mars atmosphere, its altitude will range from zero, in the night, up to 5 km at noon. The accurate gondola altitude will be determined by an altimeter. As the Balloon gondola mass is strictly limited, the altimeter total mass and power consumption are critical; maximum allowed is a few hundred grams a few tens of mWatts of average power consumption. We did propose, design, and construct the laser altimeter based on the single photon ranging technique. Topics covered include the following: principle of operation, altimeter construction, and ground tests.

  3. Single-wall carbon nanotubes based anticancer drug delivery system

    NASA Astrophysics Data System (ADS)

    Tripisciano, C.; Kraemer, K.; Taylor, A.; Borowiak-Palen, E.

    2009-08-01

    Conventional administration of chemotherapeutic agents is compromised by their lack of selectivity which is the cause of a lethal effect accomplishment on healthy tissues. Since therapeutic and diagnostic agents could functionalize the structure of carbon nanotubes (CNTs), the development of CNTs as drug containers would pave the way to their employment as nanovectors into the cells. Here a study on cisplatin (Cis-Diamminedichloroplatinum (CDDP) - a platinum-based chemotherapy drug) embedding to single-wall CNTs (SWCNTs) is shown.Being sure that the anticancer drug discharge occurred, in vitro analysis have been performed. The inhibition of prostate cancer cells (PC3 and DU145) viability from tubes encapsulating cisplatin proved the efficiency of the produced delivery system.

  4. Wavelet Speech Enhancement Based on Nonnegative Matrix Factorization

    NASA Astrophysics Data System (ADS)

    Wang, Syu-Siang; Chern, Alan; Tsao, Yu; Hung, Jeih-weih; Lu, Xugang; Lai, Ying-Hui; Su, Borching

    2016-08-01

    For most of the state-of-the-art speech enhancement techniques, a spectrogram is usually preferred than the respective time-domain raw data since it reveals more compact presentation together with conspicuous temporal information over a long time span. However, the short-time Fourier transform (STFT) that creates the spectrogram in general distorts the original signal and thereby limits the capability of the associated speech enhancement techniques. In this study, we propose a novel speech enhancement method that adopts the algorithms of discrete wavelet packet transform (DWPT) and nonnegative matrix factorization (NMF) in order to conquer the aforementioned limitation. In brief, the DWPT is first applied to split a time-domain speech signal into a series of subband signals without introducing any distortion. Then we exploit NMF to highlight the speech component for each subband. Finally, the enhanced subband signals are joined together via the inverse DWPT to reconstruct a noise-reduced signal in time domain. We evaluate the proposed DWPT-NMF based speech enhancement method on the MHINT task. Experimental results show that this new method behaves very well in prompting speech quality and intelligibility and it outperforms the convnenitional STFT-NMF based method.

  5. Wavelet based image visibility enhancement of IR images

    NASA Astrophysics Data System (ADS)

    Jiang, Qin; Owechko, Yuri; Blanton, Brendan

    2016-05-01

    Enhancing the visibility of infrared images obtained in a degraded visibility environment is very important for many applications such as surveillance, visual navigation in bad weather, and helicopter landing in brownout conditions. In this paper, we present an IR image visibility enhancement system based on adaptively modifying the wavelet coefficients of the images. In our proposed system, input images are first filtered by a histogram-based dynamic range filter in order to remove sensor noise and convert the input images into 8-bit dynamic range for efficient processing and display. By utilizing a wavelet transformation, we modify the image intensity distribution and enhance image edges simultaneously. In the wavelet domain, low frequency wavelet coefficients contain original image intensity distribution while high frequency wavelet coefficients contain edge information for the original images. To modify the image intensity distribution, an adaptive histogram equalization technique is applied to the low frequency wavelet coefficients while to enhance image edges, an adaptive edge enhancement technique is applied to the high frequency wavelet coefficients. An inverse wavelet transformation is applied to the modified wavelet coefficients to obtain intensity images with enhanced visibility. Finally, a Gaussian filter is used to remove blocking artifacts introduced by the adaptive techniques. Since wavelet transformation uses down-sampling to obtain low frequency wavelet coefficients, histogram equalization of low-frequency coefficients is computationally more efficient than histogram equalization of the original images. We tested the proposed system with degraded IR images obtained from a helicopter landing in brownout conditions. Our experimental results show that the proposed system is effective for enhancing the visibility of degraded IR images.

  6. Enhanced photocatalytic efficiency in zirconia buffered n-NiO/p-NiO single crystalline heterostructures by nanosecond laser treatment

    NASA Astrophysics Data System (ADS)

    Molaei, R.; Bayati, M. R.; Alipour, H. M.; Nori, S.; Narayan, J.

    2013-06-01

    We report the formation of NiO based single crystalline p-n junctions with enhanced photocatalytic activity induced by pulsed laser irradiation. The NiO epilayers were grown on Si(001) substrates buffered with cubic yttria-stabilized zirconia (c-YSZ) by using pulsed laser deposition. The NiO/c-YSZ/Si heterostructures were subsequently laser treated by 5 pulses of KrF excimer laser (pulse duration = 25 × 10-9 s) at lower energies. Microstructural studies, conducted by X-ray diffraction (θ-2θ and φ techniques) and high resolution transmission electron microscope, showed a cube-on-cube epitaxial relationship at the c-YSZ/Si interface; the epitaxial relationship across the NiO/c-YSZ interface was established as NiO⟨111 ⟩||c-YSZ⟨001⟩ and in-plane NiO⟨110⟩||c-YSZ⟨100⟩. Electron microscopy studies showed that the interface between the laser annealed and the pristine region as well as the NiO/c-YSZ interface was atomically sharp and crystallographically continuous. The formation of point defects, namely oxygen vacancies and NiO, due to the coupling of the laser photons with the NiO epilayers was confirmed by XPS. The p-type electrical characteristics of the pristine NiO epilayers turned to an n-type behavior and the electrical conductivity was increased by one order of magnitude after laser treatment. Photocatalytic activity of the pristine (p-NiO/c-YSZ/Si) and the laser-annealed (n-NiO/p-NiO/c-YSZ/Si) heterostructures were assessed by measuring the decomposition rate of 4-chlorophenol under UV light. The photocatalytic reaction rate constants were determined to be 0.0059 and 0.0092 min-1 for the as-deposited and the laser-treated samples, respectively. The enhanced photocatalytic efficiency was attributed to the suppressed charge carrier recombination in the NiO based p-n junctions and higher electrical conductivity. Besides, the oxygen vacancies ease the adsorption of 4-chlorophenol, hydroxyl, and water molecules to the surface. Thus, n

  7. Enhanced magnetic hysteresis in Ni-Mn-Ga single crystal and its influence on magnetic shape memory effect

    SciTech Connect

    Heczko, O. Drahokoupil, J.; Straka, L.

    2015-05-07

    Enhanced magnetic hysteresis due to boron doping in combination with magnetic shape memory effect in Ni-Mn-Ga single crystal results in new interesting functionality of magnetic shape memory (MSM) alloys such as mechanical demagnetization. In Ni{sub 50.0}Mn{sub 28.5}Ga{sub 21.5} single crystal, the boron doping increased magnetic coercivity from few Oe to 270 Oe while not affecting the transformation behavior and 10 M martensite structure. However, the magnetic field needed for MSM effect also increased in doped sample. The magnetic behavior is compared to undoped single crystal of similar composition. The evidence from the X-ray diffraction, magnetic domain structure, magnetization loops, and temperature evolution of the magnetic coercivity points out that the enhanced hysteresis is caused by stress-induced anisotropy.

  8. Alternative Induction of Meiotic Recombination From Single-Base Lesions of DNA Deaminases

    PubMed Central

    Pauklin, Siim; Burkert, Julia S.; Martin, Julie; Osman, Fekret; Weller, Sandra; Boulton, Simon J.; Whitby, Matthew C.; Petersen-Mahrt, Svend K.

    2009-01-01

    Meiotic recombination enhances genetic diversity as well as ensures proper segregation of homologous chromosomes, requiring Spo11-initiated double-strand breaks (DSBs). DNA deaminases act on regions of single-stranded DNA and deaminate cytosine to uracil (dU). In the immunoglobulin locus, this lesion will initiate point mutations, gene conversion, and DNA recombination. To begin to delineate the effect of induced base lesions on meiosis, we analyzed the effect of expressing DNA deaminases (activation-induced deaminase, AID, and APOBEC3C) in germ cells. We show that meiotic dU:dG lesions can partially rescue a spo11Δ phenotype in yeast and worm. In rec12 Schizosaccharomyces pombe, AID expression increased proper chromosome segregation, thereby enhancing spore viability, and induced low-frequency meiotic crossovers. Expression of AID in the germ cells of Caenorhabditis elegans spo-11 induced meiotic RAD-51 foci formation and chromosomal bivalency and segregation, as well as an increase in viability. RNAi experiments showed that this rescue was dependent on uracil DNA-glycosylase (Ung). Furthermore, unlike ionizing radiation-induced spo-11 rescue, AID expression did not induce large numbers of DSBs during the rescue. This suggests that the products of DNA deamination and base excision repair, such as uracil, an abasic site, or a single-stranded nick, are sufficient to initiate and alter meiotic recombination in uni- and multicellular organisms. PMID:19237686

  9. Enhanced vapor-phase processing in fluorinated Fe4 single-molecule magnets.

    PubMed

    Rigamonti, Luca; Piccioli, Marco; Malavolti, Luigi; Poggini, Lorenzo; Mannini, Matteo; Totti, Federico; Cortigiani, Brunetto; Magnani, Agnese; Sessoli, Roberta; Cornia, Andrea

    2013-05-20

    A new tetrairon(III) single-molecule magnet with enhanced volatility and processability was obtained by partial fluorination of the ancillary β-diketonato ligands. Fluorinated proligand Hpta = pivaloyltrifluoroacetone was used to assemble the bis(alkoxido)-bridged dimer [Fe2(OEt)2(pta)4] (1) in crystalline form, from which the new tetranuclear complex [Fe4(L)2(pta)6] (2) was synthesized in a one-pot reaction with H3L = 2-hydroxymethyl-2-phenylpropane-1,3-diol, NaOEt, and FeCl3 in a Et2O:EtOH solvent mixture. The structure of compound 2 was inferred from (1)H NMR, mass spectrometry, magnetic measurements, and DFT calculations. Direct current magnetic data are consistent with the expected metal-centered triangular topology for the iron(III) ions, with an antiferromagnetic coupling constant J = 16.20(6) cm(-1) between the central iron and the peripheral ones and consequent stabilization of an S = 5 spin ground state. Alternating current (ac) susceptibility measurements in 0 and 1 kOe static applied fields show the presence of a thermally activated process for magnetic relaxation, with τ0 = 2.3(1) 10(-7) s and U(eff)/kB = 9.9(1) K at zero static field and τ0 = 2.0(2) 10(-7) s and U(eff)/kB = 13.0(2) K at 1 kOe. At a pressure of 10(-7) mbar, compound 2 sublimates at (440 ± 5) K vs (500 ± 10) K for the nonfluorinated variant [Fe4(L)2(dpm)6] (Hdpm = dipivaloylmethane). According to XPS, ToF-SIMS, and ac susceptibility studies, the chemical composition, fragmentation pattern, and slow magnetic relaxation of the pristine material are retained in sublimated samples, suggesting that the molecular structure remains totally unaffected upon vapor-phase processing.

  10. Performance benefits of telerobotics and teleoperation - enhancements for an arm-based tank waste retrieval system

    SciTech Connect

    Horschel, D.S.; Gibbons, P.W.; Draper, J.V.

    1995-06-01

    This report evaluates telerobotic and teleoperational arm-based retrieval systems that require advanced robotic controls. These systems will be deployed in waste retrieval activities in Hanford`s Single Shell Tanks (SSTs). The report assumes that arm-based, retrieval systems will combine a teleoperational arm and control system enhanced by a number of advanced and telerobotic controls. The report describes many possible enhancements, spanning the full range of the control spectrum with the potential for technical maturation. The enhancements considered present a variety of choices and factors including: the enhancements to be included in the actual control system, safety, detailed task analyses, human factors, cost-benefit ratios, and availability and maturity of technology. Because the actual system will be designed by an offsite vendor, the procurement specifications must have the flexibility to allow bidders to propose a broad range of ideas, yet build in enough restrictions to filter out infeasible and undesirable approaches. At the same time they must allow selection of a technically promising proposal. Based on a preliminary analysis of the waste retrieval task, and considering factors such as operator limitations and the current state of robotics technology, the authors recommend a set of enhancements that will (1) allow the system to complete its waste retrieval mission, and (2) enable future upgrades in response to changing mission needs and technological advances.

  11. Enhanced Absorption of Nasulin™, an Ultrarapid-Acting Intranasal Insulin Formulation, Using Single Nostril Administration in Normal Subjects

    PubMed Central

    Stote, Robert; Miller, Michael; Marbury, Thomas; Shi, Leon; Strange, Poul

    2011-01-01

    Background This pharmacokinetic (PK) study was designed to investigate the maximum intranasal insulin dose that could be achieved by repeated doses in a single nostril of a nasal spray of recombinant regular human insulin 1% in combination with cyclopentadecalactone (CPE-215) 2%, a compound that enhances absorption of molecules across mucous membranes (Nasulin™, CPEX Pharmaceuticals, Inc.). Method A nine-period crossover study of 8 healthy, nonsmoking subjects (ages 18–50, body mass index <33 kg/m2, weight >70 kg) were studied. In a fasted state, subjects were randomly given 25, 50, and 75 U in a single nostril on the first day and randomly given 50, 75, and 100 U doses utilizing both nostrils on two subsequent days. After a 45-minute PK assessment, subjects were given a meal. To determine the mechanism of enhanced absorption in a single nostril, a second study utilizing 24 subjects under similar conditions received 25 U, placebo (P) that included CPE-215 plus 25 U, and 50 U in a single nostril. Results Single nostril administration revealed enhanced absorption with maximum concentrations (Cmax) of 13, 65, and 96 µU/ml for the 25, 50, and 75 U doses, respectively. Dual nostril administration in two cohorts resulted in Cmax of 31/42, 65/52, and 88/79 µU/ml for the 50, 75, and 100 U, respectively. In the second cohort, Cmax was 23, 19, 56 µU/ml for the 25, P + 25, and 50 U doses, respectively. Conclusions Repeated dosing in a single nostril resulted in enhanced absorption; this was not due to the increased CPE-215 but to the increased insulin administered. PMID:21303633

  12. Performance enhancement of thin film silicon solar cells based on distributed Bragg reflector and diffraction grating

    SciTech Connect

    Dubey, R. S.; Saravanan, S.; Kalainathan, S.

    2014-12-15

    The influence of various designing parameters were investigated and explored for high performance solar cells. Single layer grating based solar cell of 50 μm thickness gives maximum efficiency up to 24 % whereas same efficiency is achieved with the use of three bilayers grating based solar cell of 30 μm thickness. Remarkably, bilayer grating based solar cell design not only gives broadband absorption but also enhancement in efficiency with reduced cell thickness requirement. This absorption enhancement is attributed to the high reflection and diffraction from DBR and grating respectively. The obtained short-circuit current were 29.6, 32.9, 34.6 and 36.05 mA/cm{sup 2} of 5, 10, 20 and 30 μm cell thicknesses respectively. These presented designing efforts would be helpful to design and realize new generation of solar cells.

  13. Recent Advances on Luminescent Enhancement-Based Porous Silicon Biosensors.

    PubMed

    Jenie, S N Aisyiyah; Plush, Sally E; Voelcker, Nicolas H

    2016-10-01

    Luminescence-based detection paradigms have key advantages over other optical platforms such as absorbance, reflectance or interferometric based detection. However, autofluorescence, low quantum yield and lack of photostability of the fluorophore or emitting molecule are still performance-limiting factors. Recent research has shown the need for enhanced luminescence-based detection to overcome these drawbacks while at the same time improving the sensitivity, selectivity and reducing the detection limits of optical sensors and biosensors. Nanostructures have been reported to significantly improve the spectral properties of the emitting molecules. These structures offer unique electrical, optic and magnetic properties which may be used to tailor the surrounding electrical field of the emitter. Here, the main principles behind luminescence and luminescence enhancement-based detections are reviewed, with an emphasis on europium complexes as the emitting molecule. An overview of the optical porous silicon microcavity (pSiMC) as a biosensing platform and recent proof-of-concept examples on enhanced luminescence-based detection using pSiMCs are provided and discussed.

  14. Single-Particle Spectroscopic Study on Fluorescence Enhancement by Plasmon Coupled Gold Nanorod Dimers Assembled on DNA Origami.

    PubMed

    Zhang, Taishi; Gao, Nengyue; Li, Shuang; Lang, Matthew J; Xu, Qing-Hua

    2015-06-01

    Metal-enhanced fluorescence has attracted much attention due to its scientific importance and lots of potential applications. Plasmon coupled metal nanoparticles have been demonstrated to further improve the enhancement effects. Conventional studies of metal-enhanced fluorescence on the bulk systems are complicated by the ensemble average effects over many critical factors with large variations. Here, fluorescence enhancement of ATTO-655 by a plasmon coupled gold nanorod dimer fixed on a DNA origami nanobreadboard was studied on the single-particle level. A series of gold nanorod dimers with linear orientation and different gap distances ranging from 6.1 to 26.0 nm were investigated to explore the plasmon coupling effect on fluorescence enhancement. The results show that the dimer with the smallest gap (6.1 nm) gives the highest enhancement (470-fold), and the enhancement gradually decreases as the gap distance increases and eventually approaches that from a monomer (120-fold). This trend is consistent with the numerical calculation results. This study indicates that plasmon coupling in gold nanorod dimers offers further increased excitation efficiency to achieve large fluorescence enhancement.

  15. Functional long circulating single walled carbon nanotubes for fluorescent/photoacoustic imaging-guided enhanced phototherapy.

    PubMed

    Xie, Lisi; Wang, Guohao; Zhou, Hao; Zhang, Fan; Guo, Zhide; Liu, Chuan; Zhang, Xianzhong; Zhu, Lei

    2016-10-01

    Nanotherapeutics have been investigated for years, but only modest survival benefits were observed clinic. This is partially attributed to the short and rapid elimination of nanodrug after intravenous administration. In this study, a long circulation single wall carbon nanotube (SWCNT) complex was successfully fabricated through a new SWCNT dispersion agent, evans blue (EB). The complex was endowed with fluorescent imaging and photodynamic therapy ability by self-assembly loading an albumin coupled fluorescent photosensitizer, Chlorin e6 (Ce6) via the high affinity between EB and albumin. The yielding multifunctional albumin/Ce6 loaded EB/carbon nanotube-based delivery system, named ACEC, is capable of providing fluorescent and photoacoustic imaging of tumors for optimizing therapeutic time window. Synergistic photodynamic therapy (PDT) and photothermal therapy (PTT) were carried out as guided by imaging results at 24 h post-injection and achieved an efficient tumor ablation effect. Compared to PDT or PTT alone, the combined phototherapy managed to damage tumor and diminish tumor without recurrence. Overall, our study presents a SWCNT based theranostic system with great promising in dual modalities imaging guided PTT/PDT combined treatment of tumor. The applications of EB on SWCNT functionalization can be easily extended to the other nanomaterials for improving their in vivo stability and circulation time.

  16. Nanovectorization of TRAIL with single wall carbon nanotubes enhances tumor cell killing.

    PubMed

    Zakaria, Al Batoul; Picaud, Fabien; Rattier, Thibault; Pudlo, Marc; Dufour, Florent; Saviot, Lucien; Chassagnon, Rémi; Lherminier, Jeannine; Gharbi, Tijani; Micheau, Olivier; Herlem, Guillaume

    2015-02-11

    Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL or Apo2L) is a member of the tumor necrosis factor (TNF) superfamily. This type II transmembrane protein is able to bound specifically to cancer cell receptors (i.e., TRAIL-R1 (or DR4) and TRAIL-R2 (or DR5)) and to induce apoptosis without being toxic for healthy cells. Because membrane-bound TRAIL induces stronger receptor aggregation and apoptosis than soluble TRAIL, we proposed here to vectorize TRAIL using single-walled carbon nanotubes (SWCNTs) to mimic membrane TRAIL. Owing to their exceptional and revolutional properties, carbon nanotubes, especially SWCNTs, are used in a wide range of physical or, now, medical applications. Indeed due to their high mechanical resistance, their high flexibility and their hydrophobicity, SWCNTs are known to rapidly diffuse in an aqueous medium such as blood, opening the way of development of new drug nanovectors (or nanocarriers). Our TRAIL-based SWCNTs nanovectors proved to be more efficient than TRAIL alone death receptors in triggering cancer cell killing. These NPTs increased TRAIL pro-apoptotic potential by nearly 20-fold in different Human tumor cell lines including colorectal, nonsmall cell lung cancer, or hepatocarcinomas. We provide thus a proof-of-concept that TRAIL nanovector derivatives based on SWCNT may be useful to future nanomedicine therapies.

  17. Detailed Observation of Multiphoton Emission Enhancement from a Single Colloidal Quantum Dot Using a Silver-Coated AFM Tip.

    PubMed

    Takata, Hiroki; Naiki, Hiroyuki; Wang, Li; Fujiwara, Hideki; Sasaki, Keiji; Tamai, Naoto; Masuo, Sadahiro

    2016-09-14

    The enhancement of multiphoton emission from a single colloidal nanocrystal quantum dot (NQD) interacting with a plasmonic nanostructure was investigated using a silver-coated atomic force microscopy tip (AgTip) as the plasmonic nanostructure. Using the AgTip, which exhibited a well-defined localized surface plasmon (LSP) resonance band, we controlled the spectral overlap and the distance between the single NQD and the AgTip. The emission behavior of the single NQD when approaching the AgTip at the nanometer scale was measured using off-resonance (405 nm) and resonance (465 nm) excitation of the LSP. We directly observed the conversion of the single-photon emission from a single NQD to multiphoton emission with reduction of the emission lifetime at both excitation wavelengths as the NQD-AgTip distance decreased, whereas a decrease and increase in the emission intensity were observed at 405 and 465 nm excitation, respectively. By combining theoretical analysis and the numerical simulation of the AgTip, we deduced that the enhancement of the multiphoton emission was caused by the quenching of the single-exciton state due to the energy transfer from the NQD to the AgTip and that the emission intensity was increased by enhancement of the excitation rate due to the electric field of the LSP on the AgTip. These results provide evidence that the photon statistics and the photon flux from the single NQD can be manipulated by the plasmonic nanostructure through control of the spectral overlap and the distance.

  18. Peering into Cells One Molecule at a Time: Single-molecule and plasmon-enhanced fluorescence super-resolution imaging

    NASA Astrophysics Data System (ADS)

    Biteen, Julie

    2013-03-01

    Single-molecule fluorescence brings the resolution of optical microscopy down to the nanometer scale, allowing us to unlock the mysteries of how biomolecules work together to achieve the complexity that is a cell. This high-resolution, non-destructive method for examining subcellular events has opened up an exciting new frontier: the study of macromolecular localization and dynamics in living cells. We have developed methods for single-molecule investigations of live bacterial cells, and have used these techniques to investigate thee important prokaryotic systems: membrane-bound transcription activation in Vibrio cholerae, carbohydrate catabolism in Bacteroides thetaiotaomicron, and DNA mismatch repair in Bacillus subtilis. Each system presents unique challenges, and we will discuss the important methods developed for each system. Furthermore, we use the plasmon modes of bio-compatible metal nanoparticles to enhance the emissivity of single-molecule fluorophores. The resolution of single-molecule imaging in cells is generally limited to 20-40 nm, far worse than the 1.5-nm localization accuracies which have been attained in vitro. We use plasmonics to improve the brightness and stability of single-molecule probes, and in particular fluorescent proteins, which are widely used for bio-imaging. We find that gold-coupled fluorophores demonstrate brighter, longer-lived emission, yielding an overall enhancement in total photons detected. Ultimately, this results in increased localization accuracy for single-molecule imaging. Furthermore, since fluorescence intensity is proportional to local electromagnetic field intensity, these changes in decay intensity and rate serve as a nm-scale read-out of the field intensity. Our work indicates that plasmonic substrates are uniquely advantageous for super-resolution imaging, and that plasmon-enhanced imaging is a promising technique for improving live cell single-molecule microscopy.

  19. Detailed Observation of Multiphoton Emission Enhancement from a Single Colloidal Quantum Dot Using a Silver-Coated AFM Tip.

    PubMed

    Takata, Hiroki; Naiki, Hiroyuki; Wang, Li; Fujiwara, Hideki; Sasaki, Keiji; Tamai, Naoto; Masuo, Sadahiro

    2016-09-14

    The enhancement of multiphoton emission from a single colloidal nanocrystal quantum dot (NQD) interacting with a plasmonic nanostructure was investigated using a silver-coated atomic force microscopy tip (AgTip) as the plasmonic nanostructure. Using the AgTip, which exhibited a well-defined localized surface plasmon (LSP) resonance band, we controlled the spectral overlap and the distance between the single NQD and the AgTip. The emission behavior of the single NQD when approaching the AgTip at the nanometer scale was measured using off-resonance (405 nm) and resonance (465 nm) excitation of the LSP. We directly observed the conversion of the single-photon emission from a single NQD to multiphoton emission with reduction of the emission lifetime at both excitation wavelengths as the NQD-AgTip distance decreased, whereas a decrease and increase in the emission intensity were observed at 405 and 465 nm excitation, respectively. By combining theoretical analysis and the numerical simulation of the AgTip, we deduced that the enhancement of the multiphoton emission was caused by the quenching of the single-exciton state due to the energy transfer from the NQD to the AgTip and that the emission intensity was increased by enhancement of the excitation rate due to the electric field of the LSP on the AgTip. These results provide evidence that the photon statistics and the photon flux from the single NQD can be manipulated by the plasmonic nanostructure through control of the spectral overlap and the distance. PMID:27501388

  20. Single-Walled Carbon-Nanotubes-Based Organic Memory Structures.

    PubMed

    Fakher, Sundes; Nejm, Razan; Ayesh, Ahmad; Al-Ghaferi, Amal; Zeze, Dagou; Mabrook, Mohammed

    2016-01-01

    The electrical behaviour of organic memory structures, based on single-walled carbon-nanotubes (SWCNTs), metal-insulator-semiconductor (MIS) and thin film transistor (TFT) structures, using poly(methyl methacrylate) (PMMA) as the gate dielectric, are reported. The drain and source electrodes were fabricated by evaporating 50 nm gold, and the gate electrode was made from 50 nm-evaporated aluminium on a clean glass substrate. Thin films of SWCNTs, embedded within the insulating layer, were used as the floating gate. SWCNTs-based memory devices exhibited clear hysteresis in their electrical characteristics (capacitance-voltage (C-V) for MIS structures, as well as output and transfer characteristics for transistors). Both structures were shown to produce reliable and large memory windows by virtue of high capacity and reduced charge leakage. The hysteresis in the output and transfer characteristics, the shifts in the threshold voltage of the transfer characteristics, and the flat-band voltage shift in the MIS structures were attributed to the charging and discharging of the SWCNTs floating gate. Under an appropriate gate bias (1 s pulses), the floating gate is charged and discharged, resulting in significant threshold voltage shifts. Pulses as low as 1 V resulted in clear write and erase states.

  1. Single nucleotide polymorphism-based dispersal estimates using noninvasive sampling

    PubMed Central

    Norman, Anita J; Spong, Göran

    2015-01-01

    Quantifying dispersal within wild populations is an important but challenging task. Here we present a method to estimate contemporary, individual-based dispersal distance from noninvasively collected samples using a specialized panel of 96 SNPs (single nucleotide polymorphisms). One main issue in conducting dispersal studies is the requirement for a high sampling resolution at a geographic scale appropriate for capturing the majority of dispersal events. In this study, fecal samples of brown bear (Ursus arctos) were collected by volunteer citizens, resulting in a high sampling resolution spanning over 45,000 km2 in Gävleborg and Dalarna counties in Sweden. SNP genotypes were obtained for unique individuals sampled (n = 433) and subsequently used to reconstruct pedigrees. A Mantel test for isolation by distance suggests that the sampling scale was appropriate for females but not for males, which are known to disperse long distances. Euclidean distance was estimated between mother and offspring pairs identified through the reconstructed pedigrees. The mean dispersal distance was 12.9 km (SE 3.2) and 33.8 km (SE 6.8) for females and males, respectively. These results were significantly different (Wilcoxon’s rank-sum test: P-value = 0.02) and are in agreement with the previously identified pattern of male-biased dispersal. Our results illustrate the potential of using a combination of noninvasively collected samples at high resolution and specialized SNPs for pedigree-based dispersal models. PMID:26357536

  2. Single-Walled Carbon-Nanotubes-Based Organic Memory Structures.

    PubMed

    Fakher, Sundes; Nejm, Razan; Ayesh, Ahmad; Al-Ghaferi, Amal; Zeze, Dagou; Mabrook, Mohammed

    2016-01-01

    The electrical behaviour of organic memory structures, based on single-walled carbon-nanotubes (SWCNTs), metal-insulator-semiconductor (MIS) and thin film transistor (TFT) structures, using poly(methyl methacrylate) (PMMA) as the gate dielectric, are reported. The drain and source electrodes were fabricated by evaporating 50 nm gold, and the gate electrode was made from 50 nm-evaporated aluminium on a clean glass substrate. Thin films of SWCNTs, embedded within the insulating layer, were used as the floating gate. SWCNTs-based memory devices exhibited clear hysteresis in their electrical characteristics (capacitance-voltage (C-V) for MIS structures, as well as output and transfer characteristics for transistors). Both structures were shown to produce reliable and large memory windows by virtue of high capacity and reduced charge leakage. The hysteresis in the output and transfer characteristics, the shifts in the threshold voltage of the transfer characteristics, and the flat-band voltage shift in the MIS structures were attributed to the charging and discharging of the SWCNTs floating gate. Under an appropriate gate bias (1 s pulses), the floating gate is charged and discharged, resulting in significant threshold voltage shifts. Pulses as low as 1 V resulted in clear write and erase states. PMID:27598112

  3. Evolution-Operator-Based Single-Step Method for Image Processing

    PubMed Central

    Wu, Peiru; Wei, G. W.; Wang, Ge

    2006-01-01

    This work proposes an evolution-operator-based single-time-step method for image and signal processing. The key component of the proposed method is a local spectral evolution kernel (LSEK) that analytically integrates a class of evolution partial differential equations (PDEs). From the point of view PDEs, the LSEK provides the analytical solution in a single time step, and is of spectral accuracy, free of instability constraint. From the point of image/signal processing, the LSEK gives rise to a family of lowpass filters. These filters contain controllable time delay and amplitude scaling. The new evolution operator-based method is constructed by pointwise adaptation of anisotropy to the coefficients of the LSEK. The Perona-Malik-type of anisotropic diffusion schemes is incorporated in the LSEK for image denoising. A forward-backward diffusion process is adopted to the LSEK for image deblurring or sharpening. A coupled PDE system is modified for image edge detection. The resulting image edge is utilized for image enhancement. Extensive computer experiments are carried out to demonstrate the performance of the proposed method. The major advantages of the proposed method are its single-step solution and readiness for multidimensional data analysis. PMID:23165051

  4. Surface Enhanced Raman Spectroscopy (SERS) of Atmospheric Particles and Single Particle pH from Raman Microspectroscopy: Tools to Provide Greater Chemical Detail about Secondary Organic Aerosol

    NASA Astrophysics Data System (ADS)

    Ault, A. P.; Craig, R. L.; Bondy, A. L.

    2015-12-01

    The ability to probe the chemical complexity and physicochemical properties of individual organic aerosols and organic-inorganic mixtures is needed to improve our understanding of their formation and evolution in the atmosphere, as well as their impacts on climate. This work will describe two new methods being developed to probe individual particles with Raman microspectroscopy: SERS provides unprecedented sensitivity regarding the functional groups present and single particle pH provide a direct probe of atmospheric particle acidity Surface enhanced Raman spectroscopy (SERS) generates enhanced Raman signal and has been applied to atmospheric aerosol particles and model systems in the laboratory, leading to enhancements of 101-102. This has allowed rich vibrational spectra to be observed for submicron particles, with detailed functional group and phase state information. Single particle pH is been developed to allow direct observation of individual particle pH through a combination of a spectral approach and an independent method based on changes in diameter at different relative humidities. Together these provide an independent check and an important improvement on indirect methods to allow detailed chemical studies. Together, the new SERS and single particle pH methods have the potential to improve our understanding of atmospheric organic aerosol mechanisms and evolution in the atmosphere.

  5. Adaptive image contrast enhancement algorithm for point-based rendering

    NASA Astrophysics Data System (ADS)

    Xu, Shaoping; Liu, Xiaoping P.

    2015-03-01

    Surgical simulation is a major application in computer graphics and virtual reality, and most of the existing work indicates that interactive real-time cutting simulation of soft tissue is a fundamental but challenging research problem in virtual surgery simulation systems. More specifically, it is difficult to achieve a fast enough graphic update rate (at least 30 Hz) on commodity PC hardware by utilizing traditional triangle-based rendering algorithms. In recent years, point-based rendering (PBR) has been shown to offer the potential to outperform the traditional triangle-based rendering in speed when it is applied to highly complex soft tissue cutting models. Nevertheless, the PBR algorithms are still limited in visual quality due to inherent contrast distortion. We propose an adaptive image contrast enhancement algorithm as a postprocessing module for PBR, providing high visual rendering quality as well as acceptable rendering efficiency. Our approach is based on a perceptible image quality technique with automatic parameter selection, resulting in a visual quality comparable to existing conventional PBR algorithms. Experimental results show that our adaptive image contrast enhancement algorithm produces encouraging results both visually and numerically compared to representative algorithms, and experiments conducted on the latest hardware demonstrate that the proposed PBR framework with the postprocessing module is superior to the conventional PBR algorithm and that the proposed contrast enhancement algorithm can be utilized in (or compatible with) various variants of the conventional PBR algorithm.

  6. Enhancing and controlling single-atom high-harmonic generation spectra: a time-dependent density-functional scheme

    NASA Astrophysics Data System (ADS)

    Castro, Alberto; Rubio, Angel; Gross, Eberhard K. U.

    2015-08-01

    High harmonic generation (HHG) provides a flexible framework for the development of coherent light sources in the extreme-ultraviolet and soft X-ray regimes. However it suffers from low conversion efficiencies as the control of the HHG spectral and temporal characteristics requires manipulating electron trajectories on attosecond time scale. The phase matching mechanism has been employed to selectively enhance specific quantum paths leading to HHG. A few important fundamental questions remain open, among those how much of the enhancement can be achieved by the single-emitter and what is the role of correlations (or the electronic structure) in the selectivity and control of HHG generation. Here we address those questions by examining computationally the possibility of optimizing the HHG spectrum of isolated hydrogen and helium atoms by shaping the slowly varying envelope of a 800 nm, 200-cycles long laser pulse. The spectra are computed with a fully quantum mechanical description, by explicitly computing the time-dependent dipole moment of the systems using a time-dependent density-functional approach (or the single-electron Schrödinger equation for the case of H), on top of a one-dimensional model. The sought optimization corresponds to the selective enhancement of single harmonics, which we find to be significant. This selectivity is entirely due to the single atom response, and not to any propagation or phase-matching effect. Moreover, we see that the electronic correlation plays a role in the determining the degree of optimization that can be obtained.

  7. Adaptive enhancement method of infrared image based on scene feature

    NASA Astrophysics Data System (ADS)

    Zhang, Xiao; Bai, Tingzhu; Shang, Fei

    2008-12-01

    All objects emit radiation in amounts related to their temperature and their ability to emit radiation. The infrared image shows the invisible infrared radiation emitted directly. Because of the advantages, the technology of infrared imaging is applied to many kinds of fields. But compared with visible image, the disadvantages of infrared image are obvious. The characteristics of low luminance, low contrast and the inconspicuous difference target and background are the main disadvantages of infrared image. The aim of infrared image enhancement is to improve the interpretability or perception of information in infrared image for human viewers, or to provide 'better' input for other automated image processing techniques. Most of the adaptive algorithm for image enhancement is mainly based on the gray-scale distribution of infrared image, and is not associated with the actual image scene of the features. So the pertinence of infrared image enhancement is not strong, and the infrared image is not conducive to the application of infrared surveillance. In this paper we have developed a scene feature-based algorithm to enhance the contrast of infrared image adaptively. At first, after analyzing the scene feature of different infrared image, we have chosen the feasible parameters to describe the infrared image. In the second place, we have constructed the new histogram distributing base on the chosen parameters by using Gaussian function. In the last place, the infrared image is enhanced by constructing a new form of histogram. Experimental results show that the algorithm has better performance than other methods mentioned in this paper for infrared scene images.

  8. Sequence-Dependent Elasticity and Electrostatics of Single-Stranded DNA: Signatures of Base-Stacking

    PubMed Central

    McIntosh, Dustin B.; Duggan, Gina; Gouil, Quentin; Saleh, Omar A.

    2014-01-01

    Base-stacking is a key factor in the energetics that determines nucleic acid structure. We measure the tensile response of single-stranded DNA as a function of sequence and monovalent salt concentration to examine the effects of base-stacking on the mechanical and thermodynamic properties of single-stranded DNA. By comparing the elastic response of highly stacked poly(dA) and that of a polypyrimidine sequence with minimal stacking, we find that base-stacking in poly(dA) significantly enhances the polymer’s rigidity. The unstacking transition of poly(dA) at high force reveals that the intrinsic electrostatic tension on the molecule varies significantly more weakly on salt concentration than mean-field predictions. Further, we provide a model-independent estimate of the free energy difference between stacked poly(dA) and unstacked polypyrimidine, finding it to be ∼−0.25 kBT/base and nearly constant over three orders of magnitude in salt concentration. PMID:24507606

  9. Sequence-dependent elasticity and electrostatics of single-stranded DNA: signatures of base-stacking.

    PubMed

    McIntosh, Dustin B; Duggan, Gina; Gouil, Quentin; Saleh, Omar A

    2014-02-01

    Base-stacking is a key factor in the energetics that determines nucleic acid structure. We measure the tensile response of single-stranded DNA as a function of sequence and monovalent salt concentration to examine the effects of base-stacking on the mechanical and thermodynamic properties of single-stranded DNA. By comparing the elastic response of highly stacked poly(dA) and that of a polypyrimidine sequence with minimal stacking, we find that base-stacking in poly(dA) significantly enhances the polymer's rigidity. The unstacking transition of poly(dA) at high force reveals that the intrinsic electrostatic tension on the molecule varies significantly more weakly on salt concentration than mean-field predictions. Further, we provide a model-independent estimate of the free energy difference between stacked poly(dA) and unstacked polypyrimidine, finding it to be ∼-0.25 kBT/base and nearly constant over three orders of magnitude in salt concentration.

  10. Use of Single-Layer g-C3N4/Ag Hybrids for Surface-Enhanced Raman Scattering (SERS)

    NASA Astrophysics Data System (ADS)

    Jiang, Jizhou; Zou, Jing; Wee, Andrew Thye Shen; Zhang, Wenjing

    2016-09-01

    Surface-enhanced Raman scattering (SERS) substrates with high activity and stability are desirable for SERS sensing. Here, we report a new single atomic layer graphitic-C3N4 (S-g-C3N4) and Ag nanoparticles (NPs) hybrid as high-performance SERS substrates. The SERS mechanism of the highly stable S-g-C3N4/Ag substrates was systematically investigated by a combination of experiments and theoretical calculations. From the results of XPS and Raman spectroscopies, it was found that there was a strong interaction between S-g-C3N4 and Ag NPs, which facilitates the uniform distribution of Ag NPs over the edges and surfaces of S-g-C3N4 nanosheets, and induces a charge transfer from S-g-C3N4 to the oxidizing agent through the silver surface, ultimately protecting Ag NPs from oxidation. Based on the theoretical calculations, we found that the net surface charge of the Ag atoms on the S-g-C3N4/Ag substrates was positive and the Ag NPs presented high dispersibility, suggesting that the Ag atoms on the S-g-C3N4/Ag substrates were not likely to be oxidized, thereby ensuring the high stability of the S-g-C3N4/Ag substrate. An understanding of the stability mechanism in this system can be helpful for developing other effective SERS substrates with long-term stability.

  11. Use of Single-Layer g-C3N4/Ag Hybrids for Surface-Enhanced Raman Scattering (SERS)

    PubMed Central

    Jiang, Jizhou; Zou, Jing; Wee, Andrew Thye Shen; Zhang, Wenjing

    2016-01-01

    Surface-enhanced Raman scattering (SERS) substrates with high activity and stability are desirable for SERS sensing. Here, we report a new single atomic layer graphitic-C3N4 (S-g-C3N4) and Ag nanoparticles (NPs) hybrid as high-performance SERS substrates. The SERS mechanism of the highly stable S-g-C3N4/Ag substrates was systematically investigated by a combination of experiments and theoretical calculations. From the results of XPS and Raman spectroscopies, it was found that there was a strong interaction between S-g-C3N4 and Ag NPs, which facilitates the uniform distribution of Ag NPs over the edges and surfaces of S-g-C3N4 nanosheets, and induces a charge transfer from S-g-C3N4 to the oxidizing agent through the silver surface, ultimately protecting Ag NPs from oxidation. Based on the theoretical calculations, we found that the net surface charge of the Ag atoms on the S-g-C3N4/Ag substrates was positive and the Ag NPs presented high dispersibility, suggesting that the Ag atoms on the S-g-C3N4/Ag substrates were not likely to be oxidized, thereby ensuring the high stability of the S-g-C3N4/Ag substrate. An understanding of the stability mechanism in this system can be helpful for developing other effective SERS substrates with long-term stability. PMID:27687573

  12. Spatially uniform enhancement of single quantum dot emission using plasmonic grating decoupler

    PubMed Central

    Kumar, Arunandan; Weeber, Jean-Claude; Bouhelier, Alexandre; Eloi, Fabien; Buil, Stéphanie; Quélin, Xavier; Nasilowski, Michel; Dubertret, Benoit; Hermier, Jean-Pierre; Colas des Francs, Gérard

    2015-01-01

    We demonstrate a spatially uniform enhancement of individual quantum dot (QD) fluorescence emission using plasmonic grating decouplers on thin gold or silver films. Individual QDs are deposited within the grating in a controlled way to investigate the position dependency on both the radiation pattern and emission enhancement. We also describe the optimization of the grating decoupler. We achieve a fluorescence enhancement ~3 times higher than using flat plasmon film, for any QD position in the grating. PMID:26577533

  13. Calix[4]arene Based Single-Molecule Magnets

    SciTech Connect

    Karotsis, Georgios; Teat, Simon J.; Wernsdorfer, Wolfgang; Piligkos, Stergios; Dalgarno, Scott J.; Brechin, Euan K.

    2009-06-04

    Single-molecule magnets (SMMs) have been the subject of much interest in recent years because their molecular nature and inherent physical properties allow the crossover between classical and quantum physics to be observed. The macroscopic observation of quantum phenomena - tunneling between different spin states, quantum interference between tunnel paths - not only allows scientists to study quantum mechanical laws in great detail, but also provides model systems with which to investigate the possible implementation of spin-based solid state qubits and molecular spintronics. The isolation of small, simple SMMs is therefore an exciting prospect. To date almost all SMMs have been made via the self-assembly of 3d metal ions in the presence of bridging/chelating organic ligands. However, very recently an exciting new class of SMMs, based on 3d metal clusters (or single lanthanide ions) housed within polyoxometalates, has appeared. These types of molecule, in which the SMM is completely encapsulated within (or shrouded by) a 'protective' organic or inorganic sheath have much potential for design and manipulation: for example, for the removal of unwanted dipolar interactions, the introduction of redox activity, or to simply aid functionalization for surface grafting. Calix[4]arenes are cyclic (typically bowl-shaped) polyphenols that have been used extensively in the formation of versatile self-assembled supramolecular structures. Although many have been reported, p-{sup t}But-calix[4]arene and calix[4]arene (TBC4 and C4 respectively, Figure 1A) are frequently encountered due to (a) synthetic accessibility, and (b) vast potential for alteration at either the upper or lower rim of the macrocyclic framework. Within the field of supramolecular chemistry, TBC4 is well known for interesting polymorphic behavior and phase transformations within anti-parallel bi-layer arrays, while C4 often forms self-included trimers. The polyphenolic nature of calix[n]arenes (where n = 4

  14. Compressive Video Recovery Using Block Match Multi-Frame Motion Estimation Based on Single Pixel Cameras

    PubMed Central

    Bi, Sheng; Zeng, Xiao; Tang, Xin; Qin, Shujia; Lai, King Wai Chiu

    2016-01-01

    Compressive sensing (CS) theory has opened up new paths for the development of signal processing applications. Based on this theory, a novel single pixel camera architecture has been introduced to overcome the current limitations and challenges of traditional focal plane arrays. However, video quality based on this method is limited by existing acquisition and recovery methods, and the method also suffers from being time-consuming. In this paper, a multi-frame motion estimation algorithm is proposed in CS video to enhance the video quality. The proposed algorithm uses multiple frames to implement motion estimation. Experimental results show that using multi-frame motion estimation can improve the quality of recovered videos. To further reduce the motion estimation time, a block match algorithm is used to process motion estimation. Experiments demonstrate that using the block match algorithm can reduce motion estimation time by 30%. PMID:26950127

  15. An accurate single-electron pump based on a highly tunable silicon quantum dot.

    PubMed

    Rossi, Alessandro; Tanttu, Tuomo; Tan, Kuan Yen; Iisakka, Ilkka; Zhao, Ruichen; Chan, Kok Wai; Tettamanzi, Giuseppe C; Rogge, Sven; Dzurak, Andrew S; Möttönen, Mikko

    2014-06-11

    Nanoscale single-electron pumps can be used to generate accurate currents, and can potentially serve to realize a new standard of electrical current based on elementary charge. Here, we use a silicon-based quantum dot with tunable tunnel barriers as an accurate source of quantized current. The charge transfer accuracy of our pump can be dramatically enhanced by controlling the electrostatic confinement of the dot using purposely engineered gate electrodes. Improvements in the operational robustness, as well as suppression of nonadiabatic transitions that reduce pumping accuracy, are achieved via small adjustments of the gate voltages. We can produce an output current in excess of 80 pA with experimentally determined relative uncertainty below 50 parts per million.

  16. Vertically Conductive Single-Crystal SiC-Based Bragg Reflector Grown on Si Wafer.

    PubMed

    Massoubre, David; Wang, Li; Hold, Leonie; Fernandes, Alanna; Chai, Jessica; Dimitrijev, Sima; Iacopi, Alan

    2015-01-01

    Single-crystal silicon carbide (SiC) thin-films on silicon (Si) were used for the fabrication and characterization of electrically conductive distributed Bragg reflectors (DBRs) on 100 mm Si wafers. The DBRs, each composed of 3 alternating layers of SiC and Al(Ga)N grown on Si substrates, show high wafer uniformity with a typical maximum reflectance of 54% in the blue spectrum and a stopband (at 80% maximum reflectance) as large as 100 nm. Furthermore, high vertical electrical conduction is also demonstrated resulting to a density of current exceeding 70 A/cm(2) above 1.5 V. Such SiC/III-N DBRs with high thermal and electrical conductivities could be used as pseudo-substrate to enhance the efficiency of SiC-based and GaN-based optoelectronic devices on large Si wafers. PMID:26601894

  17. Compressive Video Recovery Using Block Match Multi-Frame Motion Estimation Based on Single Pixel Cameras.

    PubMed

    Bi, Sheng; Zeng, Xiao; Tang, Xin; Qin, Shujia; Lai, King Wai Chiu

    2016-01-01

    Compressive sensing (CS) theory has opened up new paths for the development of signal processing applications. Based on this theory, a novel single pixel camera architecture has been introduced to overcome the current limitations and challenges of traditional focal plane arrays. However, video quality based on this method is limited by existing acquisition and recovery methods, and the method also suffers from being time-consuming. In this paper, a multi-frame motion estimation algorithm is proposed in CS video to enhance the video quality. The proposed algorithm uses multiple frames to implement motion estimation. Experimental results show that using multi-frame motion estimation can improve the quality of recovered videos. To further reduce the motion estimation time, a block match algorithm is used to process motion estimation. Experiments demonstrate that using the block match algorithm can reduce motion estimation time by 30%.

  18. Vertically Conductive Single-Crystal SiC-Based Bragg Reflector Grown on Si Wafer

    PubMed Central

    Massoubre, David; Wang, Li; Hold, Leonie; Fernandes, Alanna; Chai, Jessica; Dimitrijev, Sima; Iacopi, Alan

    2015-01-01

    Single-crystal silicon carbide (SiC) thin-films on silicon (Si) were used for the fabrication and characterization of electrically conductive distributed Bragg reflectors (DBRs) on 100 mm Si wafers. The DBRs, each composed of 3 alternating layers of SiC and Al(Ga)N grown on Si substrates, show high wafer uniformity with a typical maximum reflectance of 54% in the blue spectrum and a stopband (at 80% maximum reflectance) as large as 100 nm. Furthermore, high vertical electrical conduction is also demonstrated resulting to a density of current exceeding 70 A/cm2 above 1.5 V. Such SiC/III-N DBRs with high thermal and electrical conductivities could be used as pseudo-substrate to enhance the efficiency of SiC-based and GaN-based optoelectronic devices on large Si wafers. PMID:26601894

  19. Anatomical noise in contrast-enhanced digital mammography. Part I. Single-energy imaging

    SciTech Connect

    Hill, Melissa L.; Yaffe, Martin J.; Mainprize, James G.; Carton, Ann-Katherine; Muller, Serge; Ebrahimi, Mehran; Jong, Roberta A.; Dromain, Clarisse

    2013-05-15

    Purpose: The use of an intravenously injected iodinated contrast agent could help increase the sensitivity of digital mammography by adding information on tumor angiogenesis. Two approaches have been made for clinical implementation of contrast-enhanced digital mammography (CEDM), namely, single-energy (SE) and dual-energy (DE) imaging. In each technique, pairs of mammograms are acquired, which are then subtracted with the intent to cancel the appearance of healthy breast tissue to permit sensitive detection and specific characterization of lesions. Patterns of contrast agent uptake in the healthy parenchyma, and uncanceled signal from background tissue create a 'clutter' that can mask or mimic an enhancing lesion. This type of 'anatomical noise' is often the limiting factor in lesion detection tasks, and thus, noise quantification may be useful for cascaded systems analysis of CEDM and for phantom development. In this work, the authors characterize the anatomical noise in CEDM clinical images and the authors evaluate the influence of the x-ray energy used for acquisition, the presence of iodine in the breast, and the timing of imaging postcontrast administration on anatomical noise. The results are presented in a two-part report, with SE CEDM described here, and DE CEDM in Part II. Methods: A power law is used to model anatomical noise in CEDM images. The exponent, {beta}, which describes the anatomical structure, and the constant {alpha}, which represents the magnitude of the noise, are determined from Wiener spectra (WS) measurements on images. A total of 42 SE CEDM cases from two previous clinical pilot studies are assessed. The parameters {alpha} and {beta} are measured both from unprocessed images and from subtracted images. Results: Consistent results were found between the two SE CEDM pilot studies, where a significant decrease in {beta} from a value of approximately 3.1 in the unprocessed images to between about 1.1 and 1.8 in the subtracted images was

  20. ENHANCED HYDROGEN PRODUCTION INTEGRATED WITH CO2 SEPARATION IN A SINGLE-STAGE REACTOR

    SciTech Connect

    Himanshu Gupta; Mahesh Iyer; Bartev Sakadjian; Liang-Shih Fan

    2005-03-10

    The water gas shift reaction (WGSR) plays a major role in increasing the hydrogen production from fossil fuels. However, the enhanced hydrogen production is limited by thermodynamic constrains posed by equilibrium limitations of WGSR. This project aims at using a mesoporous, tailored, highly reactive calcium based sorbent system for incessantly removing the CO{sub 2} product which drives the equilibrium limited WGSR forward. In addition, a pure sequestration ready CO{sub 2} stream is produced simultaneously. A detailed project vision with the description of integration of this concept with an existing coal gasification process for hydrogen production is presented. Conceptual reactor designs for investigating the simultaneous water gas shift and the CaO carbonation reactions are presented. In addition, the options for conducting in-situ sorbent regeneration under vacuum or steam are also reported. Preliminary, water gas shift reactions using high temperature shift catalyst and without any sorbent confirmed the equilibrium limitation beyond 600 C demonstrating a carbon monoxide conversion of about 80%. From detailed thermodynamic analyses performed for fuel gas streams from typical gasifiers the optimal operating temperature range to prevent CaO hydration and to effect its carbonation is between 575-830 C.

  1. Fingerprint enhancement based on MRF with curve accumulation

    NASA Astrophysics Data System (ADS)

    Huang, Zhongwen; Qi, Feihu

    2001-09-01

    The uniqueness of fingerprints has been used for identification for a long time. Automatic fingerprint identification system (AFIS) depends on minutiae to identify a person that rely heavily on the quality of fingerprint image. This paper presents a novel fingerprint enhancement scheme based on a Markov Random Field (MRF). The MRF model is applied to capture local statistical regularities of ridges and then the curve accumulation based on the MRF model is presented to enhance the fingerprint. Such procedure is repeated until the statistics difference can be got between fingerprint ridges and valleys (accumulation). In the end, the adaptive binarisation is made. The results of experiments show that this method can effectively improve the clarity of ridge and valley structures of input fingerprint images and meanwhile preserve the minutiae very well.

  2. Magnetic field induced extraordinary photoluminescence enhancement in Er{sup 3+}:YVO{sub 4} single crystal

    SciTech Connect

    Zhang, Junpei; Wang, Xia; Tang, Chaoqun; Zhong, Zhiqiang; Ma, Zongwei; Wang, Shaoliang; Han, Yibo; Han, Jun-Bo Li, Liang

    2015-08-28

    A bright green photoluminescence (PL) from {sup 4}S{sub 3∕2} → {sup 4}I{sub 15∕2} emission band in Er{sup 3+}:YVO{sub 4} single crystal has been observed with the excitation of an argon laser at 488.0 nm. More than two orders of PL enhancement have been obtained under the effect of magnetic fields, and the enhancement factor f reaches 170 when the applied magnetic field is 7.7 T under the sample temperature of 4.2 K. Unusually, the PL enhancements only happen at some certain magnetic fields (B{sub c}s), and a decrease of sample temperature will lead to the increase of f and decrease of B{sub c}. The results confirm that this PL enhancement originates from the resonance excitation of the electron transitions induced by the cross of the laser energy and the absorption energy modulated by both the magnetic field and temperature. This special PL enhancement in Er{sup 3+}:YVO{sub 4} single crystal can be applied in the calibration of pulsed high magnetic field, detection of material fine energy structures, and modulation of magneto-optical devices.

  3. Enhancing the heralded single-photon rate from a silicon nanowire by time and wavelength division multiplexing pump pulses.

    PubMed

    Zhang, X; Jizan, I; He, J; Clark, A S; Choi, D-Y; Chae, C J; Eggleton, B J; Xiong, C

    2015-06-01

    Heralded single photons produced on a silicon chip represent an integrated photon source solution for scalable photonic quantum technologies. The key limitation of such sources is their non-deterministic nature introduced by the stochastic spontaneous four-wave mixing (SFWM) process. Active spatial and temporal multiplexing can improve this by enhancing the single-photon rate without degrading the quantum signal-to-noise ratio. Here, taking advantage of the broad bandwidth of SFWM in a silicon nanowire, we experimentally demonstrate heralded single-photon generation from a silicon nanowire pumped by time and wavelength division multiplexed pulses. We show a 90±5% enhancement on the heralded photon rate at the cost of only 14±2% reduction to the signal-to-noise ratio, close to the performance found using only time division multiplexed pulses. As single-photon events are distributed to multiple wavelength channels, this new scheme overcomes the saturation limit of avalanche single-photon detectors and will improve the ultimate performance of such photon sources. PMID:26030539

  4. Enhancement of Tb(III) -Cu(II) Single-Molecule Magnet Performance through Structural Modification.

    PubMed

    Heras Ojea, María José; Milway, Victoria A; Velmurugan, Gunasekaran; Thomas, Lynne H; Coles, Simon J; Wilson, Claire; Wernsdorfer, Wolfgang; Rajaraman, Gopalan; Murrie, Mark

    2016-08-26

    We report a series of 3d-4f complexes {Ln2 Cu3 (H3 L)2 Xn } (X=OAc(-) , Ln=Gd, Tb or X=NO3 (-) , Ln=Gd, Tb, Dy, Ho, Er) using the 2,2'-(propane-1,3-diyldiimino)bis[2-(hydroxylmethyl)propane-1,3-diol] (H6 L) pro-ligand. All complexes, except that in which Ln=Gd, show slow magnetic relaxation in zero applied dc field. A remarkable improvement of the energy barrier to reorientation of the magnetisation in the {Tb2 Cu3 (H3 L)2 Xn } complexes is seen by changing the auxiliary ligands (X=OAc(-) for NO3 (-) ). This leads to the largest reported relaxation barrier in zero applied dc field for a Tb/Cu-based single-molecule magnet. Ab initio CASSCF calculations performed on mononuclear Tb(III) models are employed to understand the increase in energy barrier and the calculations suggest that the difference stems from a change in the Tb(III) coordination environment (C4v versus Cs ). PMID:27484259

  5. Enhanced sidewall functionalization of single-wall carbon nanotubes using nitric acid.

    PubMed

    Tobias, Gerard; Shao, Lidong; Ballesteros, Belin; Green, Malcolm L H

    2009-10-01

    When a sample of as-made single-walled carbon nanotubes (SWNTs) is treated with nitric acid, oxidation debris are formed due to the functionalization (mainly carboxylation) of the amorphous carbon present in the sample and a continuous coating along the carbon nanotube walls is created preventing the sidewall functionalization of the SWNTs. This oxidation debris can be easily removed by an aqueous base wash leaving behind a sample with a low degree of functionality. After removal of the amorphous carbon (by steam purification) from a sample of as-made SWNTs, the resulting purified SWNTs are readily carboxylated on the walls by nitric acid treatment. The use of steam for the purification of SWNTs samples allows the removal of the amorphous carbon and graphitic layers coating the metal particles present in the sample without altering the tubular structure of the SWNTs. The exposed metal particles can then be easily removed by an acid wash. Comparison between the steam treatment and molten sodium hydroxide treatment is made.

  6. Enhancement of catalysis and functional expression of a bacterial laccase by single amino acid replacement.

    PubMed

    Nasoohi, Nikoo; Khajeh, Khosro; Mohammadian, Mahdi; Ranjbar, Bijan

    2013-09-01

    Structure-function relationships underlying laccases properties are very limited that makes these enzymes interesting for protein engineering approaches. Therefore in the current study, a thermostable laccase that was isolated from Bacillus sp. HR03 with the ability of bilirubin oxidation besides its laccase and tyrosinase activity is used. The extensive application of this enzyme is limited by its low expression level in Escherichia coli. Based on sequence alignments and structural studies, three single amino acid substitutions, D500G, D500E, D500S and a glycine insertion, are introduced using site-directed mutagenesis to evaluate the role of Asp(500) located in the C-terminal segment close to the T1 copper center. Substitution of aspartic acid with less sterically hindered, conserved residue such as glycine increase kcat (2.3 fold) and total activity (7.3 fold) which is accompanied by a significant increase in the expression level up to 3 fold. Biochemical characterization and structural studies using far-UV CD and fluorescence spectroscopy reveal the importance of C-terminal copper-binding loop in the laccase functional expression and catalytic efficiency. Kinetic characterization of the purified mutants toward 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), syringaldazine (SGZ) and bilirubin, shows that substrate specificity is left unchanged. PMID:23707861

  7. Silicon nanohybrid-based surface-enhanced Raman scattering sensors.

    PubMed

    Wang, Houyu; Jiang, Xiangxu; Lee, Shuit-Tong; He, Yao

    2014-11-01

    Nanomaterial-based surface-enhanced Raman scattering (SERS) sensors are highly promising analytical tools, capable of ultrasensitive, multiplex, and nondestructive detection of chemical and biological species. Extensive efforts have been made to design various silicon nanohybrid-based SERS substrates such as gold/silver nanoparticle (NP)-decorated silicon nanowires, Au/Ag NP-decorated silicon wafers (AuNP@Si), and so forth. In comparison to free AuNP- and AgNP-based SERS sensors, the silicon nanohybrid-based SERS sensors feature higher enhancement factors (EFs) and excellent reproducibility, since SERS hot spots are efficiently coupled and stabilized through interconnection to the semiconducting silicon substrates. Consequently, in the past decade, giant advancements in the development of silicon nanohybrid-based SERS sensors have been witnessed for myriad sensing applications. In this review, the representative achievements related to the design of high-performance silicon nanohybrid-based SERS sensors and their use for chemical and biological analysis are reviewed in a detailed way. Furthermore, the major opportunities and challenges in this field are discussed from a broad perspective and possible future directions.

  8. Plasmon resonance-based optical trapping of single and multiple Au nanoparticles.

    SciTech Connect

    Toussaint, K. C.; Liu, M.; Pelton, M.; Pesic, J.; Guffey, M.; Guyot-Sionnest, P.; Scherer, N. F.; Univ. of Chicago

    2007-01-01

    The plasmon resonance-based optical trapping (PREBOT) method is used to achieve stable trapping of metallic nanoparticles of different shapes and composition, including Au bipyramids and Au/Ag core/shell nanorods. In all cases the longitudinal plasmon mode of these anisotropic particles is used to enhance the gradient force of an optical trap, thereby increasing the strength of the trap potential. Specifically, the trapping laser is slightly detuned to the long-wavelength side of the longitudinal plasmon resonance where the sign of the real component of the polarizability leads to an attractive gradient force. A second (femtosecond pulsed) laser is used to excite two-photon fluorescence for detection of the trapped nanoparticles. Two-photon fluorescence time trajectories are recorded for up to 20 minutes for single and multiple particles in the trap. In the latter case, a stepwise increase reflects sequential loading of single Au bipyramids. The nonlinearity of the amplitude and noise with step number are interpreted as arising from interactions or enhanced local fields among the trapped particles and fluctuations in the arrangements thereof.

  9. Single molecule transistor based nanopore for the detection of nicotine

    SciTech Connect

    Ray, S. J.

    2014-12-28

    A nanopore based detection methodology was proposed and investigated for the detection of Nicotine. This technique uses a Single Molecular Transistor working as a nanopore operational in the Coulomb Blockade regime. When the Nicotine molecule is pulled through the nanopore area surrounded by the Source(S), Drain (D), and Gate electrodes, the charge stability diagram can detect the presence of the molecule and is unique for a specific molecular structure. Due to the weak coupling between the different electrodes which is set by the nanopore size, the molecular energy states stay almost unaffected by the electrostatic environment that can be realised from the charge stability diagram. Identification of different orientation and position of the Nicotine molecule within the nanopore area can be made from specific regions of overlap between different charge states on the stability diagram that could be used as an electronic fingerprint for detection. This method could be advantageous and useful to detect the presence of Nicotine in smoke which is usually performed using chemical chromatography techniques.

  10. An Autonomous Underwater Recorder Based on a Single Board Computer

    PubMed Central

    Caldas-Morgan, Manuel; Alvarez-Rosario, Alexander; Rodrigues Padovese, Linilson

    2015-01-01

    As industrial activities continue to grow on the Brazilian coast, underwater sound measurements are becoming of great scientific importance as they are essential to evaluate the impact of these activities on local ecosystems. In this context, the use of commercial underwater recorders is not always the most feasible alternative, due to their high cost and lack of flexibility. Design and construction of more affordable alternatives from scratch can become complex because it requires profound knowledge in areas such as electronics and low-level programming. With the aim of providing a solution; a well succeeded model of a highly flexible, low-cost alternative to commercial recorders was built based on a Raspberry Pi single board computer. A properly working prototype was assembled and it demonstrated adequate performance levels in all tested situations. The prototype was equipped with a power management module which was thoroughly evaluated. It is estimated that it will allow for great battery savings on long-term scheduled recordings. The underwater recording device was successfully deployed at selected locations along the Brazilian coast, where it adequately recorded animal and manmade acoustic events, among others. Although power consumption may not be as efficient as that of commercial and/or micro-processed solutions, the advantage offered by the proposed device is its high customizability, lower development time and inherently, its cost. PMID:26076479

  11. An Autonomous Underwater Recorder Based on a Single Board Computer.

    PubMed

    Caldas-Morgan, Manuel; Alvarez-Rosario, Alexander; Rodrigues Padovese, Linilson

    2015-01-01

    As industrial activities continue to grow on the Brazilian coast, underwater sound measurements are becoming of great scientific importance as they are essential to evaluate the impact of these activities on local ecosystems. In this context, the use of commercial underwater recorders is not always the most feasible alternative, due to their high cost and lack of flexibility. Design and construction of more affordable alternatives from scratch can become complex because it requires profound knowledge in areas such as electronics and low-level programming. With the aim of providing a solution; a well succeeded model of a highly flexible, low-cost alternative to commercial recorders was built based on a Raspberry Pi single board computer. A properly working prototype was assembled and it demonstrated adequate performance levels in all tested situations. The prototype was equipped with a power management module which was thoroughly evaluated. It is estimated that it will allow for great battery savings on long-term scheduled recordings. The underwater recording device was successfully deployed at selected locations along the Brazilian coast, where it adequately recorded animal and manmade acoustic events, among others. Although power consumption may not be as efficient as that of commercial and/or micro-processed solutions, the advantage offered by the proposed device is its high customizability, lower development time and inherently, its cost.

  12. Single molecule transistor based nanopore for the detection of nicotine

    NASA Astrophysics Data System (ADS)

    Ray, S. J.

    2014-12-01

    A nanopore based detection methodology was proposed and investigated for the detection of Nicotine. This technique uses a Single Molecular Transistor working as a nanopore operational in the Coulomb Blockade regime. When the Nicotine molecule is pulled through the nanopore area surrounded by the Source(S), Drain (D), and Gate electrodes, the charge stability diagram can detect the presence of the molecule and is unique for a specific molecular structure. Due to the weak coupling between the different electrodes which is set by the nanopore size, the molecular energy states stay almost unaffected by the electrostatic environment that can be realised from the charge stability diagram. Identification of different orientation and position of the Nicotine molecule within the nanopore area can be made from specific regions of overlap between different charge states on the stability diagram that could be used as an electronic fingerprint for detection. This method could be advantageous and useful to detect the presence of Nicotine in smoke which is usually performed using chemical chromatography techniques.

  13. CFD-Based Design Optimization for Single Element Rocket Injector

    NASA Technical Reports Server (NTRS)

    Vaidyanathan, Rajkumar; Tucker, Kevin; Papila, Nilay; Shyy, Wei

    2003-01-01

    To develop future Reusable Launch Vehicle concepts, we have conducted design optimization for a single element rocket injector, with overall goals of improving reliability and performance while reducing cost. Computational solutions based on the Navier-Stokes equations, finite rate chemistry, and the k-E turbulence closure are generated with design of experiment techniques, and the response surface method is employed as the optimization tool. The design considerations are guided by four design objectives motivated by the consideration in both performance and life, namely, the maximum temperature on the oxidizer post tip, the maximum temperature on the injector face, the adiabatic wall temperature, and the length of the combustion zone. Four design variables are selected, namely, H2 flow angle, H2 and O2 flow areas with fixed flow rates, and O2 post tip thickness. In addition to establishing optimum designs by varying emphasis on the individual objectives, better insight into the interplay between design variables and their impact on the design objectives is gained. The investigation indicates that improvement in performance or life comes at the cost of the other. Best compromise is obtained when improvements in both performance and life are given equal importance.

  14. An Autonomous Underwater Recorder Based on a Single Board Computer.

    PubMed

    Caldas-Morgan, Manuel; Alvarez-Rosario, Alexander; Rodrigues Padovese, Linilson

    2015-01-01

    As industrial activities continue to grow on the Brazilian coast, underwater sound measurements are becoming of great scientific importance as they are essential to evaluate the impact of these activities on local ecosystems. In this context, the use of commercial underwater recorders is not always the most feasible alternative, due to their high cost and lack of flexibility. Design and construction of more affordable alternatives from scratch can become complex because it requires profound knowledge in areas such as electronics and low-level programming. With the aim of providing a solution; a well succeeded model of a highly flexible, low-cost alternative to commercial recorders was built based on a Raspberry Pi single board computer. A properly working prototype was assembled and it demonstrated adequate performance levels in all tested situations. The prototype was equipped with a power management module which was thoroughly evaluated. It is estimated that it will allow for great battery savings on long-term scheduled recordings. The underwater recording device was successfully deployed at selected locations along the Brazilian coast, where it adequately recorded animal and manmade acoustic events, among others. Although power consumption may not be as efficient as that of commercial and/or micro-processed solutions, the advantage offered by the proposed device is its high customizability, lower development time and inherently, its cost. PMID:26076479

  15. Single domain PEMFC model based on agglomerate catalyst geometry

    NASA Astrophysics Data System (ADS)

    Siegel, N. P.; Ellis, M. W.; Nelson, D. J.; von Spakovsky, M. R.

    A steady two-dimensional computational model for a proton exchange membrane (PEM) fuel cell is presented. The model accounts for species transport, electrochemical kinetics, energy transport, current distribution, and water uptake and release in the catalyst layer. The governing differential equations are solved over a single computational domain, which consists of a gas channel, gas diffusion layer, and catalyst layer for both the anode and cathode sides of the cell as well as the solid polymer membrane. The model for the catalyst regions is based on an agglomerate geometry, which requires water species to exist in both dissolved and gaseous forms simultaneously. Data related to catalyst morphology, which was required by the model, was obtained via a microscopic analysis of a commercially available membrane electrode assembly (MEA). The coupled set of differential equations is solved with the commercial computational fluid dynamics (CFD) solver, CFDesign™, and is readily adaptable with respect to geometry and material property definitions. The results show that fuel cell performance is highly dependent on catalyst structure, specifically the relative volume fractions of gas pores and polymer membrane contained within the active region as well as the geometry of the individual agglomerates.

  16. Compositional Effects on Nickel-Base Superalloy Single Crystal Microstructures

    NASA Technical Reports Server (NTRS)

    MacKay, Rebecca A.; Gabb, Timothy P.; Garg,Anita; Rogers, Richard B.; Nathal, Michael V.

    2012-01-01

    Fourteen nickel-base superalloy single crystals containing 0 to 5 wt% chromium (Cr), 0 to 11 wt% cobalt (Co), 6 to 12 wt% molybdenum (Mo), 0 to 4 wt% rhenium (Re), and fixed amounts of aluminum (Al) and tantalum (Ta) were examined to determine the effect of bulk composition on basic microstructural parameters, including gamma' solvus, gamma' volume fraction, volume fraction of topologically close-packed (TCP) phases, phase chemistries, and gamma - gamma'. lattice mismatch. Regression models were developed to describe the influence of bulk alloy composition on the microstructural parameters and were compared to predictions by a commercially available software tool that used computational thermodynamics. Co produced the largest change in gamma' solvus over the wide compositional range used in this study, and Mo produced the largest effect on the gamma lattice parameter and the gamma - gamma' lattice mismatch over its compositional range, although Re had a very potent influence on all microstructural parameters investigated. Changing the Cr, Co, Mo, and Re contents in the bulk alloy had a significant impact on their concentrations in the gamma matrix and, to a smaller extent, in the gamma' phase. The gamma phase chemistries exhibited strong temperature dependencies that were influenced by the gamma and gamma' volume fractions. A computational thermodynamic modeling tool significantly underpredicted gamma' solvus temperatures and grossly overpredicted the amount of TCP phase at 982 C. Furthermore, the predictions by the software tool for the gamma - gamma' lattice mismatch were typically of the wrong sign and magnitude, but predictions could be improved if TCP formation was suspended within the software program. However, the statistical regression models provided excellent estimations of the microstructural parameters based on bulk alloy composition, thereby demonstrating their usefulness.

  17. Quantitative single-mode fiber based PS-OCT with single input polarization state using Mueller matrix.

    PubMed

    Ding, Zhenyang; Liang, Chia-Pin; Tang, Qinggong; Chen, Yu

    2015-05-01

    We present a simple but effective method to quantitatively measure the birefringence of tissue by an all single-mode fiber (SMF) based polarization-sensitive optical coherence tomography (PS-OCT) with single input polarization state. We theoretically verify that our SMF based PS-OCT system can quantify the phase retardance and optic axis orientation after a simple calibration process using a quarter wave plate (QWP). Based on the proposed method, the quantification of the phase retardance and optic axis orientation of a Berek polarization compensator and biological tissues were demonstrated. PMID:26137383

  18. Enhancing Traditional Behavioral Parent Training for Single Mothers of Children with ADHD

    ERIC Educational Resources Information Center

    Chacko, Anil; Wymbs, Brian T.; Wymbs, Frances A.; Pelham, William E.; Swanger-Gagne, Michelle S.; Girio, Erin; Pirvics, Lauma; Herbst, Laura; Guzzo, Jamie; Phillips, Carlie; O'Connor, Briannon

    2009-01-01

    Behavioral parent training is an efficacious treatment for attention-deficit/hyperactivity disorder (ADHD). However, single-mother households are at high risk for poor outcomes during and following behavioral parent training. This study randomly assigned cohorts of 120 single mothers of children (ages 5-12 years) with ADHD to a waitlist control…

  19. Enhancing Accountability in Behavioral Consultation through the Use of Single-Case Designs

    ERIC Educational Resources Information Center

    Segool, Natasha K.; Brinkman, Tara M.; Carlson, John S.

    2007-01-01

    Single-case design and progress monitoring methodologies are efficient and cost-effective strategies for increasing accountability for indirect service provision. Single-case design conceptualizes the treatment of an individual as an experimental process that can be monitored over time and evaluated for effectiveness. Increasingly in clinical,…

  20. Optical Sensors Based on Single Arm Thin Film Waveguide Interferometer

    NASA Technical Reports Server (NTRS)

    Sarkisov, S. S.; Diggs, D.; Curley, M.; Adamovsky, Grigory (Technical Monitor)

    2001-01-01

    Single-arm double-mode double-order optical waveguide interferometer utilizes interference between two propagating modes of different orders. Sensing effect results from the change in propagation conditions of the modes caused by the environment. The waveguide is made as an open asymmetric slab structure containing a dye-doped polymer film onto a fused quartz substrate. It is more sensitive to the change of environment than its conventional polarimetric analog using orthogonal modes (TE and TM) of the same order. The sensor still preserves the option of operating in polarimetric regime using a variety of mode combinations such as TE(sub 0)/TM(sub 0) (conventional), TE(sub 0)/TM(sub 1), TE(sub 1)/TM(sub 0), or TE(sub 1)/TM(sub 1) but can also work in nonpolarimetric regime using combinations TE(sub 0)/TM(sub 1) or TE(sub 0)/TM(sub 1). Utilization of different mode combinations simultaneously makes the device more versatile. Application of the sensor to gas sensing is based on doping polymer film with an organic indicator dye sensitive to a particular gas. Change of optical absorption spectrum of the dye caused by the gaseous pollutant results change of the reactive index of the dye-doped polymer film that can be detected by the sensor. As an indicator dyes, we utilize Bromocresol Purple doped into polymer poly(methyl) methacrylate, which shows a reversible growth of the absorption peak neat 600 nm after exposure to wet ammonia. We have built a breadboard prototype of the sensor with He-Ne laser as a light source and with a single mode fiber input and a multimode fiber output. The prototype showed sensitivity to temperature change of the order of 2 C per one full oscillation of the signal. The sensitivity of the sensor to the presence of wet ammonia is 200 ppm per one full oscillation of the signal. The further improvements include switching to a longer wavelength laser source (750-nm semiconductor laser), substitution of poly(methyl) methacrylate with hydrophilic

  1. Nanoscale mapping of excitonic processes in single-layer MoS2 using tip-enhanced photoluminescence microscopy.

    PubMed

    Su, Weitao; Kumar, Naresh; Mignuzzi, Sandro; Crain, Jason; Roy, Debdulal

    2016-05-19

    In two-dimensional (2D) semiconductors, photoluminescence originating from recombination processes involving neutral electron-hole pairs (excitons) and charged complexes (trions) is strongly affected by the localized charge transfer due to inhomogeneous interactions with the local environment and surface defects. Herein, we demonstrate the first nanoscale mapping of excitons and trions in single-layer MoS2 using the full spectral information obtained via tip-enhanced photoluminescence (TEPL) microscopy along with tip-enhanced Raman spectroscopy (TERS) imaging of a 2D flake. Finally, we show the mapping of the PL quenching centre in single-layer MoS2 with an unprecedented spatial resolution of 20 nm. In addition, our research shows that unlike in aperture-scanning near field microscopy, preferential exciton emission mapping at the nanoscale using TEPL and Raman mapping using TERS can be obtained simultaneously using this method that can be used to correlate the structural and excitonic properties. PMID:27152366

  2. Nanoscale mapping of excitonic processes in single-layer MoS2 using tip-enhanced photoluminescence microscopy.

    PubMed

    Su, Weitao; Kumar, Naresh; Mignuzzi, Sandro; Crain, Jason; Roy, Debdulal

    2016-05-19

    In two-dimensional (2D) semiconductors, photoluminescence originating from recombination processes involving neutral electron-hole pairs (excitons) and charged complexes (trions) is strongly affected by the localized charge transfer due to inhomogeneous interactions with the local environment and surface defects. Herein, we demonstrate the first nanoscale mapping of excitons and trions in single-layer MoS2 using the full spectral information obtained via tip-enhanced photoluminescence (TEPL) microscopy along with tip-enhanced Raman spectroscopy (TERS) imaging of a 2D flake. Finally, we show the mapping of the PL quenching centre in single-layer MoS2 with an unprecedented spatial resolution of 20 nm. In addition, our research shows that unlike in aperture-scanning near field microscopy, preferential exciton emission mapping at the nanoscale using TEPL and Raman mapping using TERS can be obtained simultaneously using this method that can be used to correlate the structural and excitonic properties.

  3. Osmium-Based Pyrimidine Contrast Tags for Enhanced Nanopore-Based DNA Base Discrimination

    PubMed Central

    Henley, Robert Y.; Vazquez-Pagan, Ana G.; Johnson, Michael; Kanavarioti, Anastassia; Wanunu, Meni

    2015-01-01

    Nanopores are a promising platform in next generation DNA sequencing. In this platform, an individual DNA strand is threaded into nanopore using an electric field, and enzyme-based ratcheting is used to move the strand through the detector. During this process the residual ion current through the pore is measured, which exhibits unique levels for different base combinations inside the pore. While this approach has shown great promise, accuracy is not optimal because the four bases are chemically comparable to one another, leading to small differences in current obstruction. Nucleobase-specific chemical tagging can be a viable approach to enhancing the contrast between different bases in the sequence. Herein we show that covalent modification of one or both of the pyrimidine bases by an osmium bipyridine complex leads to measureable differences in the blockade amplitudes of DNA molecules. We qualitatively determine the degree of osmylation of a DNA strand by passing it through a solid-state nanopore, and are thus able to gauge T and C base content. In addition, we show that osmium bipyridine reacts with dsDNA, leading to substantially different current blockade levels than exhibited for bare dsDNA. This work serves as a proof of principle for nanopore sequencing and mapping via base-specific DNA osmylation. PMID:26657869

  4. Osmium-Based Pyrimidine Contrast Tags for Enhanced Nanopore-Based DNA Base Discrimination.

    PubMed

    Henley, Robert Y; Vazquez-Pagan, Ana G; Johnson, Michael; Kanavarioti, Anastassia; Wanunu, Meni

    2015-01-01

    Nanopores are a promising platform in next generation DNA sequencing. In this platform, an individual DNA strand is threaded into nanopore using an electric field, and enzyme-based ratcheting is used to move the strand through the detector. During this process the residual ion current through the pore is measured, which exhibits unique levels for different base combinations inside the pore. While this approach has shown great promise, accuracy is not optimal because the four bases are chemically comparable to one another, leading to small differences in current obstruction. Nucleobase-specific chemical tagging can be a viable approach to enhancing the contrast between different bases in the sequence. Herein we show that covalent modification of one or both of the pyrimidine bases by an osmium bipyridine complex leads to measureable differences in the blockade amplitudes of DNA molecules. We qualitatively determine the degree of osmylation of a DNA strand by passing it through a solid-state nanopore, and are thus able to gauge T and C base content. In addition, we show that osmium bipyridine reacts with dsDNA, leading to substantially different current blockade levels than exhibited for bare dsDNA. This work serves as a proof of principle for nanopore sequencing and mapping via base-specific DNA osmylation.

  5. Osmium-Based Pyrimidine Contrast Tags for Enhanced Nanopore-Based DNA Base Discrimination.

    PubMed

    Henley, Robert Y; Vazquez-Pagan, Ana G; Johnson, Michael; Kanavarioti, Anastassia; Wanunu, Meni

    2015-01-01

    Nanopores are a promising platform in next generation DNA sequencing. In this platform, an individual DNA strand is threaded into nanopore using an electric field, and enzyme-based ratcheting is used to move the strand through the detector. During this process the residual ion current through the pore is measured, which exhibits unique levels for different base combinations inside the pore. While this approach has shown great promise, accuracy is not optimal because the four bases are chemically comparable to one another, leading to small differences in current obstruction. Nucleobase-specific chemical tagging can be a viable approach to enhancing the contrast between different bases in the sequence. Herein we show that covalent modification of one or both of the pyrimidine bases by an osmium bipyridine complex leads to measureable differences in the blockade amplitudes of DNA molecules. We qualitatively determine the degree of osmylation of a DNA strand by passing it through a solid-state nanopore, and are thus able to gauge T and C base content. In addition, we show that osmium bipyridine reacts with dsDNA, leading to substantially different current blockade levels than exhibited for bare dsDNA. This work serves as a proof of principle for nanopore sequencing and mapping via base-specific DNA osmylation. PMID:26657869

  6. Sensitivity enhancement of grating interferometer based two-dimensional sensor arrays using two-wavelength readout

    SciTech Connect

    Ferhanoglu, Onur; Urey, Hakan

    2011-07-01

    Diffraction gratings integrated with microelectromechanical systems (MEMS) sensors offer displacement measurements with subnanometer sensitivity. However, the sensitivity of the interferometric readout may drop significantly based on the gap between the grating and the reference surface. A two-wavelength (2-{lambda}) readout method was previously tested using a single MEMS sensor for illustrating increased displacement measurement capability. This work demonstrates sensitivity enhancement on a sensor array with large scale parallelization ({approx}20,000 sensors). The statistical representation, which is developed to model sensitivity enhancement within a grating based sensor array, is supported by experimental results using a thermal sensor array. In the experiments, two lasers at different wavelengths (633 and 650 nm) illuminate the thermal sensor array from the backside, time-sequentially. The diffracted first order light from the array is imaged onto a single CCD camera. The target scene is reconstructed by observing the change in the first diffracted order diffraction intensity for both wavelengths. Merging of the data from two measurements with two lasers was performed by taking the larger of the two CCD measurements with respect to the reference image for each sensor. {approx}30% increase in the average sensitivity was demonstrated for a 160x120 pixel IR sensor array. Proposed architecture is also applicable to a variety of sensing applications, such as parallel biosensing and atomic force microscopy, for improved displacement measurements and enhanced sensitivity.

  7. Dengue Virus prM-Specific Human Monoclonal Antibodies with Virus Replication-Enhancing Properties Recognize a Single Immunodominant Antigenic Site

    PubMed Central

    Smith, Scott A.; Nivarthi, Usha K.; de Alwis, Ruklanthi; Kose, Nurgun; Sapparapu, Gopal; Bombardi, Robin; Kahle, Kristen M.; Pfaff, Jennifer M.; Lieberman, Sherri; Doranz, Benjamin J.

    2015-01-01

    ABSTRACT The proposed antibody-dependent enhancement (ADE) mechanism for severe dengue virus (DENV) disease suggests that non-neutralizing serotype cross-reactive antibodies generated during a primary infection facilitate entry into Fc receptor bearing cells during secondary infection, resulting in enhanced viral replication and severe disease. One group of cross-reactive antibodies that contributes considerably to this serum profile target the premembrane (prM) protein. We report here the isolation of a large panel of naturally occurring human monoclonal antibodies (MAbs) obtained from subjects following primary DENV serotype 1, 2, or 3 or secondary natural DENV infections or following primary DENV serotype 1 live attenuated virus vaccination to determine the antigenic landscape on the prM protein that is recognized by human antibodies. We isolated 25 prM-reactive human MAbs, encoded by diverse antibody-variable genes. Competition-binding studies revealed that all of the antibodies bound to a single major antigenic site on prM. Alanine scanning-based shotgun mutagenesis epitope mapping studies revealed diverse patterns of fine specificity of various clones, suggesting that different antibodies use varied binding poses to recognize several overlapping epitopes within the immunodominant site. Several of the antibodies interacted with epitopes on both prM and E protein residues. Despite the diverse genetic origins of the antibodies and differences in the fine specificity of their epitopes, each of these prM-reactive antibodies was capable of enhancing the DENV infection of Fc receptor-bearing cells. IMPORTANCE Antibodies may play a critical role in the pathogenesis of enhanced DENV infection and disease during secondary infections. A substantial proportion of enhancing antibodies generated in response to natural dengue infection are directed toward the prM protein. The fine specificity of human prM antibodies is not understood. Here, we isolated a panel of dengue pr

  8. 3D nanostar dimers with a sub-10-nm gap for single-/few-molecule surface-enhanced raman scattering.

    PubMed

    Chirumamilla, Manohar; Toma, Andrea; Gopalakrishnan, Anisha; Das, Gobind; Zaccaria, Remo Proietti; Krahne, Roman; Rondanina, Eliana; Leoncini, Marco; Liberale, Carlo; De Angelis, Francesco; Di Fabrizio, Enzo

    2014-04-16

    Plasmonic nanostar-dimers, decoupled from the substrate, have been fabricated by combining electron-beam lithography and reactive-ion etching techniques. The 3D architecture, the sharp tips of the nanostars and the sub-10 nm gap size promote the formation of giant electric-field in highly localized hot-spots. The single/few molecule detection capability of the 3D nanostar-dimers has been demonstrated by Surface-Enhanced Raman Scattering.

  9. Enhanced sputtering yields from single-ion impacts on gold nanorods.

    PubMed

    Greaves, G; Hinks, J A; Busby, P; Mellors, N J; Ilinov, A; Kuronen, A; Nordlund, K; Donnelly, S E

    2013-08-01

    Sputtering yields, enhanced by more than an order of magnitude, have been observed for 80 keV Xe ion irradiation of monocrystalline Au nanorods. Yields are in the range 100-1900  atoms/ion compared with values for a flat surface of ≈50. This enhancement results in part from the proximity of collision cascades and ensuing thermal spikes to the nanorod surfaces. Molecular dynamic modeling reveals that the range of incident angles occurring for irradiation of nanorods and the larger number of atoms in "explosively ejected" atomic clusters make a significant contribution to the enhanced yield. PMID:23971585

  10. Short Peptides Enhance Single Cell Adhesion and Viability onMicroarrays

    SciTech Connect

    Veiseh, Mandana; Veiseh, Omid; Martin, Michael C.; Asphahani,Fareid; Zhang, Miqin

    2007-01-19

    Single cell patterning holds important implications forbiology, biochemistry, biotechnology, medicine, and bioinformatics. Thechallenge for single cell patterning is to produce small islands hostingonly single cells and retaining their viability for a prolonged period oftime. This study demonstrated a surface engineering approach that uses acovalently bound short peptide as a mediator to pattern cells withimproved single cell adhesion and prolonged cellular viabilityon goldpatterned SiO2 substrates. The underlying hypothesis is that celladhesion is regulated bythe type, availability, and stability ofeffective cell adhesion peptides, and thus covalently bound shortpeptides would promote cell spreading and, thus, single cell adhesion andviability. The effectiveness of this approach and the underlyingmechanism for the increased probability of single cell adhesion andprolonged cell viability by short peptides were studied by comparingcellular behavior of human umbilical cord vein endothelial cells on threemodelsurfaces whose gold electrodes were immobilized with fibronectin,physically adsorbed Arg-Glu-Asp-Val-Tyr, and covalently boundLys-Arg-Glu-Asp-Val-Tyr, respectively. The surface chemistry and bindingproperties were characterized by reflectance Fourier transform infraredspectroscopy. Both short peptides were superior to fibronectin inproducing adhesion of only single cells, whereas the covalently boundpeptide also reduced apoptosis and necrosisof adhered cells. Controllingcell spreading by peptide binding domains to regulate apoptosis andviability represents a fundamental mechanism in cell-materialsinteraction and provides an effective strategy in engineering arrays ofsingle cells.

  11. Highly sensitive immunoassay of protein molecules based on single nanoparticle fluorescence detection in a nanowell

    NASA Astrophysics Data System (ADS)

    Han, Jin-Hee; Kim, Hee-Joo; Lakshmana, Sudheendra; Gee, Shirley J.; Hammock, Bruce D.; Kennedy, Ian M.

    2011-03-01

    A nanoarray based-single molecule detection system was developed for detecting proteins with extremely high sensitivity. The nanoarray was able to effectively trap nanoparticles conjugated with biological sample into nanowells by integrating with an electrophoretic particle entrapment system (EPES). The nanoarray/EPES is superior to other biosensor using immunoassays in terms of saving the amounts of biological solution and enhancing kinetics of antibody binding due to reduced steric hindrance from the neighboring biological molecules. The nanoarray patterned onto a layer of PMMA and LOL on conductive and transparent indium tin oxide (ITO)-glass slide by using e-beam lithography. The suspension of 500 nm-fluorescent (green emission)-carboxylated polystyrene (PS) particles coated with protein-A followed by BDE 47 polyclonal antibody was added to the chip that was connected to the positive voltage. The droplet was covered by another ITO-coated-glass slide and connected to a ground terminal. After trapping the particles into the nanowells, the solution of different concentrations of anti-rabbit- IgG labeled with Alexa 532 was added for an immunoassay. A single molecule detection system could quantify the anti-rabbit IgG down to atto-mole level by counting photons emitted from the fluorescent dye bound to a single nanoparticle in a nanowell.

  12. DNA-Directed Antibody Immobilization for Enhanced Detection of Single Viral Pathogens.

    PubMed

    Seymour, Elif; Daaboul, George G; Zhang, Xirui; Scherr, Steven M; Ünlü, Nese Lortlar; Connor, John H; Ünlü, M Selim

    2015-10-20

    Here, we describe the use of DNA-conjugated antibodies for rapid and sensitive detection of whole viruses using a single-particle interferometric reflectance imaging sensor (SP-IRIS), a simple, label-free biosensor capable of imaging individual nanoparticles. First, we characterize the elevation of the antibodies conjugated to a DNA sequence on a three-dimensional (3-D) polymeric surface using a fluorescence axial localization technique, spectral self-interference fluorescence microscopy (SSFM). Our results indicate that using DNA linkers results in significant elevation of the antibodies on the 3-D polymeric surface. We subsequently show the specific detection of pseudotyped vesicular stomatitis virus (VSV) as a model virus on SP-IRIS platform. We demonstrate that DNA-conjugated antibodies improve the capture efficiency by achieving the maximal virus capture for an antibody density as low as 0.72 ng/mm(2), whereas for unmodified antibody, the optimal virus capture requires six times greater antibody density on the sensor surface. We also show that using DNA conjugated anti-EBOV GP (Ebola virus glycoprotein) improves the sensitivity of EBOV-GP carrying VSV detection compared to directly immobilized antibodies. Furthermore, utilizing a DNA surface for conversion to an antibody array offers an easier manufacturing process by replacing the antibody printing step with DNA printing. The DNA-directed immobilization technique also has the added advantages of programmable sensor surface generation based on the need and resistance to high temperatures required for microfluidic device fabrication. These capabilities improve the existing SP-IRIS technology, resulting in a more robust and versatile platform, ideal for point-of-care diagnostics applications. PMID:26378807

  13. Superconducting transport in single and parallel double InAs quantum dot Josephson junctions with Nb-based superconducting electrodes

    SciTech Connect

    Baba, Shoji Sailer, Juergen; Deacon, Russell S.; Oiwa, Akira; Shibata, Kenji; Hirakawa, Kazuhiko; Tarucha, Seigo

    2015-11-30

    We report conductance and supercurrent measurements for InAs single and parallel double quantum dot Josephson junctions contacted with Nb or NbTiN superconducting electrodes. Large superconducting gap energy, high critical field, and large switching current are observed, all reflecting the features of Nb-based electrodes. For the parallel double dots, we observe an enhanced supercurrent when both dots are on resonance, which may reflect split Cooper pair tunneling.

  14. Gold nanoparticles with tipped surface structures as substrates for single-particle surface-enhanced Raman spectroscopy: concave nanocubes, nanotrisoctahedra, and nanostars.

    PubMed

    Zhang, Qingfeng; Large, Nicolas; Wang, Hui

    2014-10-01

    We demonstrate that Au nanoparticles with tipped surface structures, such as concave nanocubes, nanotrisoctahedra, and nanostars, possess size-dependent tunable plasmon resonances and intense near-field enhancements exploitable for single-particle surface-enhanced Raman spectroscopy (spSERS) under near-infrared excitation. We report a robust seed-mediated growth method for the selective fabrication of Au concave nanocubes, nanotrisoctahedra, and nanostars with fine-controlled particle sizes and narrow size distributions. Through tight control over particle sizes, the plasmon resonances of the nanoparticles can be fine-tuned over a broad spectral range with respect to the excitation laser, allowing us to systematically quantify the SERS enhancements on individual nanoparticles as a function of particle size for each particle geometry. Understanding of the geometry-dependent plasmonic characteristics and SERS activities of the nanoparticles is further enhanced by finite-difference time-domain (FDTD) calculations. Our results clearly show that strong SERS enhancements can be obtained and further optimized on individual Au nanoparticles with nanoengineered "hot spots" on their tipped surfaces when the plasmon resonances of the nanoparticles are tuned to the optimal spectral regions with respect to the excitation laser wavelength. Using tunable plasmonic nanoparticles with tipped surface structures as substrates for spSERS represents a highly promising and feasible approach to the optimization of SERS-based sensing and imaging applications.

  15. Peripheral nerve enhancement based on multi-scale Hessian matrix

    NASA Astrophysics Data System (ADS)

    Ma, Xiuli; Li, Hui; Zhou, Xueli; Wan, Wanggen

    2011-06-01

    To improve the precision of nerve segmentation in CT images, a new comparability function is proposed in this paper to enhance the contrast between nerve structure and other surrounding tissues. It is based on nerve's characteristic, i.e. dark tubular structure, and a thorough analysis of the multi-scale Hessian matrix. By comparability function, the gray range of interested nerve structure can be automatically determined, which combines the multi-scale Hessian matrix eigenvalues with intensity information of original nerve CT images. The experimental results show that the improved algorithm can not only enhance the continuous nerve of tubular structure, but also clearly reflect its bifurcations and crossovers. It is very important and significant to the computer-aided disease diagnosis of peripheral nervous system.

  16. Image contrast enhancement based on a local standard deviation model

    SciTech Connect

    Chang, Dah-Chung; Wu, Wen-Rong

    1996-12-31

    The adaptive contrast enhancement (ACE) algorithm is a widely used image enhancement method, which needs a contrast gain to adjust high frequency components of an image. In the literature, the gain is usually inversely proportional to the local standard deviation (LSD) or is a constant. But these cause two problems in practical applications, i.e., noise overenhancement and ringing artifact. In this paper a new gain is developed based on Hunt`s Gaussian image model to prevent the two defects. The new gain is a nonlinear function of LSD and has the desired characteristic emphasizing the LSD regions in which details are concentrated. We have applied the new ACE algorithm to chest x-ray images and the simulations show the effectiveness of the proposed algorithm.

  17. Transition from single to multi-walled carbon nanotubes grown by inductively coupled plasma enhanced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Bissett, Mark A.; Barlow, Anders J.; Shapter, Joe G.; Quinton, Jamie S.

    2011-08-01

    In this work a simple and up-scalable technique for creating arrays of high purity carbon nanotubes via plasma enhanced chemical vapor deposition is demonstrated. Inductively coupled plasma enhanced chemical vapor deposition was used with methane and argon mixtures to grow arrays in a repeatable and controllable way. Changing the growth conditions such as temperature and growth time led to a transition between single and multi-walled carbon nanotubes and was investigated. This transition from single to multi-walled carbon nanotubes is attributed to a decrease in catalytic activity with time due to amorphous carbon deposition combined with a higher susceptibility of single-walled nanotubes to plasma etching. Patterning of these arrays was achieved by physical masking during the iron catalyst deposition process. The low growth pressure of 100 mTorr and lack of reducing gas such as ammonia or hydrogen or alumina supporting layer further show this to be a simple yet versatile procedure. These arrays were then characterized using scanning electron microscopy, Raman spectroscopy and x-ray photoelectron spectroscopy. It was also observed that at high temperature (550 °C) single-walled nanotube growth was preferential while lower temperatures (450 °C) produced mainly multi-walled arrays.

  18. Hydrogel Pore-Size Modulation for Enhanced Single-Cell Western Blotting.

    PubMed

    Duncombe, Todd A; Kang, Chi-Chih; Maity, Santanu; Ward, Toby M; Pegram, Mark D; Murthy, Niren; Herr, Amy E

    2016-01-13

    Pore-gradient microgel arrays enable thousands of parallel high-resolution single-cell protein electrophoresis separations for targets accross a wide molecular mass (25-289 kDa), yet within 1 mm separation distances. Dual crosslinked hydrogels facilitate gel-pore expansion after electrophoresis for efficient and uniform immunoprobing. The photopatterned, light-activated, and acid-expandable hydrogel underpins single-cell protein analysis, here for oncoprotein-related signaling in human breast biopsy.

  19. Transmission enhancement based on strong interference in metal-semiconductor layered film for energy harvesting

    PubMed Central

    Li, Qiang; Du, Kaikai; Mao, Kening; Fang, Xu; Zhao, Ding; Ye, Hui; Qiu, Min

    2016-01-01

    A fundamental strategy to enhance optical transmission through a continuous metallic film based on strong interference dominated by interface phase shift is developed. In a metallic film coated with a thin semiconductor film, both transmission and absorption are simultaneously enhanced as a result of dramatically reduced reflection. For a 50-nm-thick Ag film, experimental transmission enhancement factors of 4.5 and 9.5 are realized by exploiting Ag/Si non-symmetric and Si/Ag/Si symmetric geometries, respectively. These planar layered films for transmission enhancement feature ultrathin thickness, broadband and wide-angle operation, and reduced resistance. Considering one of their potential applications as transparent metal electrodes in solar cells, a calculated 182% enhancement in the total transmission efficiency relative to a single metallic film is expected. This strategy relies on no patterned nanostructures and thereby may power up a wide spectrum of energy-harvesting applications such as thin-film photovoltaics and surface photocatalysis. PMID:27404510

  20. Transmission enhancement based on strong interference in metal-semiconductor layered film for energy harvesting.

    PubMed

    Li, Qiang; Du, Kaikai; Mao, Kening; Fang, Xu; Zhao, Ding; Ye, Hui; Qiu, Min

    2016-01-01

    A fundamental strategy to enhance optical transmission through a continuous metallic film based on strong interference dominated by interface phase shift is developed. In a metallic film coated with a thin semiconductor film, both transmission and absorption are simultaneously enhanced as a result of dramatically reduced reflection. For a 50-nm-thick Ag film, experimental transmission enhancement factors of 4.5 and 9.5 are realized by exploiting Ag/Si non-symmetric and Si/Ag/Si symmetric geometries, respectively. These planar layered films for transmission enhancement feature ultrathin thickness, broadband and wide-angle operation, and reduced resistance. Considering one of their potential applications as transparent metal electrodes in solar cells, a calculated 182% enhancement in the total transmission efficiency relative to a single metallic film is expected. This strategy relies on no patterned nanostructures and thereby may power up a wide spectrum of energy-harvesting applications such as thin-film photovoltaics and surface photocatalysis. PMID:27404510

  1. Fiber-integrated diamond-based single photon source.

    PubMed

    Schröder, Tim; Schell, Andreas W; Kewes, Günter; Aichele, Thomas; Benson, Oliver

    2011-01-12

    An alignment free, micrometer-scale single photon source consisting of a single quantum emitter on an optical fiber operating at room temperature is demonstrated. It easily integrates into fiber optic networks for quantum cryptography or quantum metrology applications.(1) Near-field coupling of a single nitrogen-vacancy center is achieved in a bottom-up approach by placing a preselected nanodiamond directly on the fiber facet. Its high photon collection efficiency is equivalent to a far-field collection via an objective with a numerical aperture of 0.82. Furthermore, simultaneous excitation and re-collection through the fiber is possible by introducing a fiber-connected single emitter sensor. PMID:21138271

  2. Design for an efficient single photon source based on a single quantum dot embedded in a parabolic solid immersion lens.

    PubMed

    Devaraj, Vasanthan; Baek, Jongseo; Jang, Yudong; Jeong, Hyuk; Lee, Donghan

    2016-04-18

    We have designed a single photon emitter based on a single quantum dot embedded within a single mode parabolic solid immersion lens (pSIL) and a capping low-index pSIL. Numerical simulations predicted that the emitter performance should exhibit a high photon collection efficiency with excellent far-field emission properties, broadband operation, and good tolerance in its geometric (spatial configuration) parameters. Good geometric tolerance in a single-mode pSIL without yielding significant losses in the photon collection efficiency is advantageous for device fabrication. The low-index top pSIL layer provided this structure with a high photon collection efficiency, even in the case of a small numerical aperture (NA). Photon collection efficiencies of 64% and 78% were expected for NA values of 0.41 and 0.5, respectively. In addition to the benefits listed above, our combined pSIL design provided excellent broadband performance in a 100 nm range.

  3. An organic-inorganic broadband photodetector based on a single polyaniline nanowire doped with quantum dots.

    PubMed

    Yang, Xianguang; Liu, Yong; Lei, Hongxiang; Li, Baojun

    2016-08-25

    The capability to detect light over a broad waveband is highly important for practical optoelectronic applications and has been achieved with photodetectors of one-dimensional inorganic nanomaterials such as Si, ZnO, and GaN. However, achieving high speed responsivity over an entire waveband within such a photodetector remains a challenge. Here we demonstrate a broadband photodetector using a single polyaniline nanowire doped with quantum dots that is highly responsive over a broadband from 350 to 700 nm. The high responsivity is due to the high density of trapping states at the enormous interfaces between polyaniline and quantum dots. The interface trapping can effectively reduce the recombination rate and enhance the efficiency for light detection. Furthermore, a tunable spectral range can be achieved by size-based spectral tuning of quantum dots. The use of organic-inorganic hybrid polyaniline nanowires in broadband photodetection may offer novel functionalities in optoelectronic devices and circuits. PMID:27417337

  4. An organic-inorganic broadband photodetector based on a single polyaniline nanowire doped with quantum dots.

    PubMed

    Yang, Xianguang; Liu, Yong; Lei, Hongxiang; Li, Baojun

    2016-08-25

    The capability to detect light over a broad waveband is highly important for practical optoelectronic applications and has been achieved with photodetectors of one-dimensional inorganic nanomaterials such as Si, ZnO, and GaN. However, achieving high speed responsivity over an entire waveband within such a photodetector remains a challenge. Here we demonstrate a broadband photodetector using a single polyaniline nanowire doped with quantum dots that is highly responsive over a broadband from 350 to 700 nm. The high responsivity is due to the high density of trapping states at the enormous interfaces between polyaniline and quantum dots. The interface trapping can effectively reduce the recombination rate and enhance the efficiency for light detection. Furthermore, a tunable spectral range can be achieved by size-based spectral tuning of quantum dots. The use of organic-inorganic hybrid polyaniline nanowires in broadband photodetection may offer novel functionalities in optoelectronic devices and circuits.

  5. A Triplex Ribozyme Expression System Based on a Single Hairpin Ribozyme

    PubMed Central

    Aquino-Jarquin, Guillermo; Benítez-Hess, María Luisa; DiPaolo, Joseph A.

    2008-01-01

    Triplex ribozyme (RZ) configurations allow for the individual activity of trans-acting RZs in multiple expression cassettes (multiplex), thereby increasing target cleavage relative to conventionally expressed RZs. Although hairpin RZs have been advantageously compared to hammerhead RZs, their longer size and structural features complicated triplex design. We present a triplex expression system based on a single hairpin RZ with trans-cleavage capability and simple engineering. The system was tested in vitro using cis- and trans-cleavage kinetic assays against a known target RNA from HPV-16 E6/E7 mRNA. Single and multiplex triplex RZ constructs were more efficient in cleaving the target than tandem-cloned hairpin RZs, suggesting that the release of individual RZs enhanced trans-cleavage kinetics. Multiplex systems constructed with two different hairpin RZs resulted in better trans-cleavage compared to standard double-RZ constructs. In addition, the triplex RZ performed cis- and trans-cleavage in cervical cancer cells. The use of triplex configurations with multiplex RZs permit differential targeting of the same or different RNA, thus improving potential use against unstable targets. This prototype will provide the basis for the development of future RZ-based therapies and technologies. PMID:18707243

  6. Ultrasensitive organic phototransistors with multispectral response based on thin-film/single-crystal bilayer structures

    NASA Astrophysics Data System (ADS)

    Pinto, R. M.; Gouveia, W.; Neves, A. I. S.; Alves, H.

    2015-11-01

    We report on highly efficient organic phototransistors (OPTs) based on thin-film/single-crystal planar bilayer junctions between 5,6,11,12-tetraphenyltetracene (rubrene) and [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM). The OPTs show good field-effect characteristics in the dark, with high hole-mobility (4-5 cm2 V-1 s-1), low-contact resistance (20 kΩ cm), and low-operating voltage (≤5 V). Excellent sensing capabilities allow for light detection in the 400-750 nm range, with photocurrent/dark current ratio as high as 4 × 104, responsivity on the order of 20 AW-1 at 27 μW cm-2, and an external quantum efficiency of 52 000%. Photocurrent generation is attributed to enhanced electron and hole transfer at the interface between rubrene and PC61BM, and fast response times are observed as a consequence of the high-mobility of the interfaces. The optoelectronic properties exhibited in these OPTs outperform those typically provided by a-Si based devices, enabling future applications where multifunctionality in a single-device is sought.

  7. Ultrasensitive organic phototransistors with multispectral response based on thin-film/single-crystal bilayer structures

    SciTech Connect

    Pinto, R. M.; Gouveia, W.; Neves, A. I. S.; Alves, H.

    2015-11-30

    We report on highly efficient organic phototransistors (OPTs) based on thin-film/single-crystal planar bilayer junctions between 5,6,11,12-tetraphenyltetracene (rubrene) and [6,6]-phenyl-C{sub 61}-butyric acid methyl ester (PC{sub 61}BM). The OPTs show good field-effect characteristics in the dark, with high hole-mobility (4–5 cm{sup 2} V{sup −1} s{sup −1}), low-contact resistance (20 kΩ cm), and low-operating voltage (≤5 V). Excellent sensing capabilities allow for light detection in the 400–750 nm range, with photocurrent/dark current ratio as high as 4 × 10{sup 4}, responsivity on the order of 20 AW{sup −1} at 27 μW cm{sup −2}, and an external quantum efficiency of 52 000%. Photocurrent generation is attributed to enhanced electron and hole transfer at the interface between rubrene and PC{sub 61}BM, and fast response times are observed as a consequence of the high-mobility of the interfaces. The optoelectronic properties exhibited in these OPTs outperform those typically provided by a-Si based devices, enabling future applications where multifunctionality in a single-device is sought.

  8. Enhanced Genetic Analysis of Single Human Bioparticles Recovered by Simplified Micromanipulation from Forensic ‘Touch DNA’ Evidence

    PubMed Central

    Farash, Katherine; Hanson, Erin K.; Ballantyne, Jack

    2015-01-01

    DNA profiles can be obtained from ‘touch DNA’ evidence, which comprises microscopic traces of human biological material. Current methods for the recovery of trace DNA employ cotton swabs or adhesive tape to sample an area of interest. However, such a ‘blind-swabbing’ approach will co-sample cellular material from the different individuals, even if the individuals’ cells are located in geographically distinct locations on the item. Thus, some of the DNA mixtures encountered in touch DNA samples are artificially created by the swabbing itself. In some instances, a victim’s DNA may be found in significant excess thus masking any potential perpetrator’s DNA. In order to circumvent the challenges with standard recovery and analysis methods, we have developed a lower cost, ‘smart analysis’ method that results in enhanced genetic analysis of touch DNA evidence. We describe an optimized and efficient micromanipulation recovery strategy for the collection of bio-particles present in touch DNA samples, as well as an enhanced amplification strategy involving a one-step 5 µl microvolume lysis/STR amplification to permit the recovery of STR profiles from the bio-particle donor(s). The use of individual or few (i.e., “clumps”) bioparticles results in the ability to obtain single source profiles. These procedures represent alternative enhanced techniques for the isolation and analysis of single bioparticles from forensic touch DNA evidence. While not necessary in every forensic investigation, the method could be highly beneficial for the recovery of a single source perpetrator DNA profile in cases involving physical assault (e.g., strangulation) that may not be possible using standard analysis techniques. Additionally, the strategies developed here offer an opportunity to obtain genetic information at the single cell level from a variety of other non-forensic trace biological material. PMID:25867046

  9. Optimization of Polarimetric Contrast Enhancement Based on Fisher Criterion

    NASA Astrophysics Data System (ADS)

    Deng, Qiming; Chen, Jiong; Yang, Jian

    The optimization of polarimetric contrast enhancement (OPCE) is a widely used method for maximizing the received power ratio of a desired target versus an undesired target (clutter). In this letter, a new model of the OPCE is proposed based on the Fisher criterion. By introducing the well known two-class problem of linear discriminant analysis (LDA), the proposed model is to enlarge the normalized distance of mean value between the target and the clutter. In addition, a cross-iterative numerical method is proposed for solving the optimization with a quadratic constraint. Experimental results with the polarimetric SAR (POLSAR) data demonstrate the effectiveness of the proposed method.

  10. Room-temperature single photon sources with definite circular and linear polarizations based on single-emitter fluorescence in liquid crystal hosts

    NASA Astrophysics Data System (ADS)

    Bissell, Luke J.; Lukishova, Svetlana G.; Schmid, Ansgar W.; Hahn, Megan A.; Evans, Chris M.; Krauss, Todd D.; Stroud, Carlos R., Jr.; Boyd, Robert W.

    2010-09-01

    Experimental results of two room-temperature, robust and efficient single-photon sources with definite circular and linear polarization using single-emitter fluorescence in cholesteric and nematic liquid crystal hosts are discussed. For single emitters, we used nanocrystal quantum dots, single color centers in nanodiamonds, and single dye molecules. Single-photon sources based on single emitters in liquid crystals are the room temperature alternatives to cryogenic single-photon sources base on semiconductor heterostructured quantum dots in microcavities prepared by molecular beam epitaxy.

  11. Thin film transistors using preferentially grown semiconducting single-walled carbon nanotube networks by water-assisted plasma-enhanced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Kim, Un Jeong; Lee, Eun Hong; Kim, Jong Min; Min, Yo-Sep; Kim, Eunseong; Park, Wanjun

    2009-07-01

    Nearly perfect semiconducting single-walled carbon nanotube random network thin film transistors were fabricated and their reproducible transport properties were investigated. The networked single-walled carbon nanotubes were directly grown by water-assisted plasma-enhanced chemical vapor deposition. Optical analysis confirmed that the nanotubes were mostly semiconductors without clear metallic resonances in both the Raman and the UV-vis-IR spectroscopy. The transistors made by the nanotube networks whose density was much larger than the percolation threshold also showed no metallic paths. Estimation based on the conductance change of semiconducting nanotubes in the SWNT network due to applied gate voltage difference (conductance difference for on and off state) indicated a preferential growth of semiconducting nanotubes with an advantage of water-assisted PECVD. The nanotube transistors showed 10-5 of on/off ratio and ~8 cm2 V-1 s-1 of field effect mobility.

  12. Thin film transistors using preferentially grown semiconducting single-walled carbon nanotube networks by water-assisted plasma-enhanced chemical vapor deposition.

    PubMed

    Kim, Un Jeong; Lee, Eun Hong; Kim, Jong Min; Min, Yo-Sep; Kim, Eunseong; Park, Wanjun

    2009-07-22

    Nearly perfect semiconducting single-walled carbon nanotube random network thin film transistors were fabricated and their reproducible transport properties were investigated. The networked single-walled carbon nanotubes were directly grown by water-assisted plasma-enhanced chemical vapor deposition. Optical analysis confirmed that the nanotubes were mostly semiconductors without clear metallic resonances in both the Raman and the UV-vis-IR spectroscopy. The transistors made by the nanotube networks whose density was much larger than the percolation threshold also showed no metallic paths. Estimation based on the conductance change of semiconducting nanotubes in the SWNT network due to applied gate voltage difference (conductance difference for on and off state) indicated a preferential growth of semiconducting nanotubes with an advantage of water-assisted PECVD. The nanotube transistors showed 10(-5) of on/off ratio and approximately 8 cm2 V(-1) s(-1) of field effect mobility. PMID:19567966

  13. {116} faceted anatase single-crystalline nanosheet arrays: facile synthesis and enhanced electrochemical performances

    NASA Astrophysics Data System (ADS)

    Li, Feng; Li, Xiaoning; Peng, Ranran; Zhai, Xiaofang; Yang, Shangfeng; Fu, Zhengping; Lu, Yalin

    2014-10-01

    Single-crystalline anatase TiO2 nanosheet arrays were synthesized on a transparent conductive fluorine-doped tin oxide (FTO) substrate with a unique one-step alcohol-thermal process. The nanosheets were nearly vertically grown on the FTO substrate along their <11&cmb.macr;0> zone, and they were dominated by {116} facets. The as-fabricated {116} faceted single-crystalline anatase nanosheet arrays exhibit a much higher reduction capacity and a much better electrochemical reversibility than both {001} faceted anatase single-crystalline nanosheet arrays and P25 film. The results indicate a promising application potential for the new material in the photoelectrochemical field.Single-crystalline anatase TiO2 nanosheet arrays were synthesized on a transparent conductive fluorine-doped tin oxide (FTO) substrate with a unique one-step alcohol-thermal process. The nanosheets were nearly vertically grown on the FTO substrate along their <11&cmb.macr;0> zone, and they were dominated by {116} facets. The as-fabricated {116} faceted single-crystalline anatase nanosheet arrays exhibit a much higher reduction capacity and a much better electrochemical reversibility than both {001} faceted anatase single-crystalline nanosheet arrays and P25 film. The results indicate a promising application potential for the new material in the photoelectrochemical field. Electronic supplementary information (ESI) available: Photo of the large area STNA-116, FESEM images of STNA-001 and STNA-116 with a series of growth time, the enlarged XRD pattern, the simulated SAED pattern, the reflectance spectra, the cyclic voltammograms of P25 on the FTO substrate. See DOI: 10.1039/c4nr04248d

  14. Single-atom based coherent quantum interference device structure.

    PubMed

    Naydenov, Borislav; Rungger, Ivan; Mantega, Mauro; Sanvito, Stefano; Boland, John J

    2015-05-13

    We describe the fabrication, operation principles, and simulation of a coherent single-atom quantum interference device (QID) structure on Si(100) controlled by the properties of single atoms. The energy and spatial distribution of the wave functions associated with the device are visualized by scanning tunneling spectroscopy and the amplitude and phase of the evanescent wave functions that couple into the quantum well states are directly measured, including the action of an electrostatic gate. Density functional theory simulations were employed to simulate the electronic structure of the device structure, which is in excellent agreement with the measurements. Simulations of device transmission demonstrate that our coherent single-atom QID can have ON-OFF ratios in excess of 10(3) with potentially minimal power dissipation.

  15. Single-atom based coherent quantum interference device structure.

    PubMed

    Naydenov, Borislav; Rungger, Ivan; Mantega, Mauro; Sanvito, Stefano; Boland, John J

    2015-05-13

    We describe the fabrication, operation principles, and simulation of a coherent single-atom quantum interference device (QID) structure on Si(100) controlled by the properties of single atoms. The energy and spatial distribution of the wave functions associated with the device are visualized by scanning tunneling spectroscopy and the amplitude and phase of the evanescent wave functions that couple into the quantum well states are directly measured, including the action of an electrostatic gate. Density functional theory simulations were employed to simulate the electronic structure of the device structure, which is in excellent agreement with the measurements. Simulations of device transmission demonstrate that our coherent single-atom QID can have ON-OFF ratios in excess of 10(3) with potentially minimal power dissipation. PMID:25826690

  16. Two different factors act separately or together to specify functionally distinct activities at a single transcriptional enhancer.

    PubMed Central

    DeFranco, D; Yamamoto, K R

    1986-01-01

    The expression of genes fused downstream of the Moloney murine sarcoma virus (MoMSV) long terminal repeat is stimulated by glucocorticoids. We mapped the glucocorticoid response element that conferred this hormonal regulation and found that it is a hormone-dependent transcriptional enhancer, designated Sg; it resides within DNA fragments that also carry a previously described enhancer element (B. Levinson, G. Khoury, G. Vande Woude, and P. Gruss, Nature [London] 295:568-572, 1982), here termed Sa, whose activity is independent of the hormone. Nuclease footprinting revealed that purified glucocorticoid receptor bound at multiple discrete sites within and at the borders of the tandemly repeated sequence motif that defines Sa. The Sa and Sg activities stimulated the apparent efficiency of cognate or heterologous promoter utilization, individually providing modest enhancement and in concert yielding higher levels of activity. A deletion mutant lacking most of the tandem repeat but retaining a single receptor footprint sequence lost Sa activity but still conferred Sg activity. The two enhancer components could also be distinguished physiologically: both were operative within cultured rat fibroblasts, but only Sg activity was detectable in rat exocrine pancreas cells. Therefore, the sequence determinants of Sa and Sg activity may be interdigitated, and when both components are active, the receptor and a putative Sa factor can apparently bind and act simultaneously. We concluded that MoMSV enhancer activity is effected by at least two distinct binding factors, suggesting that combinatorial regulation of promoter function can be mediated even from a single genetic element. Images PMID:3023887

  17. Nano-manipulation of diamond-based single photon sources.

    PubMed

    Ampem-Lassen, E; Simpson, D A; Gibson, B C; Trpkovski, S; Hossain, F M; Huntington, S T; Ganesan, K; Hollenberg, L C L; Prawer, S

    2009-07-01

    The ability to manipulate nano-particles at the nano-scale is critical for the development of active quantum systems. This paper presents a technique to manipulate diamond nano-crystals at the nano-scale using a scanning electron microscope, nano-manipulator and custom tapered optical fibre probes. The manipulation of a approximately 300 nm diamond crystal, containing a single nitrogen-vacancy centre, onto the endface of an optical fibre is demonstrated. The emission properties of the single photon source post manipulation are in excellent agreement with those observed on the original substrate.

  18. Enhanced deammonification of livestock wastewater using Brocadia caroliniensis and HPNS in single tank process

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In this work we describe new findings that allowed rapid implementation of deammonification reaction in livestock anaerobic digestion effluents using mixtures of two bacterial cultures and a one-stage process (partial nitritation and anammox in a single tank). The bacterial cultures were high perf...

  19. Plasmonic antennas and zero-mode waveguides to enhance single molecule fluorescence detection and fluorescence correlation spectroscopy toward physiological concentrations.

    PubMed

    Punj, Deep; Ghenuche, Petru; Moparthi, Satish Babu; de Torres, Juan; Grigoriev, Victor; Rigneault, Hervé; Wenger, Jérôme

    2014-01-01

    Single-molecule approaches to biology offer a powerful new vision to elucidate the mechanisms that underpin the functioning of living cells. However, conventional optical single molecule spectroscopy techniques such as Förster fluorescence resonance energy transfer (FRET) or fluorescence correlation spectroscopy (FCS) are limited by diffraction to the nanomolar concentration range, far below the physiological micromolar concentration range where most biological reaction occur. To breach the diffraction limit, zero-mode waveguides (ZMW) and plasmonic antennas exploit the surface plasmon resonances to confine and enhance light down to the nanometer scale. The ability of plasmonics to achieve extreme light concentration unlocks an enormous potential to enhance fluorescence detection, FRET, and FCS. Single molecule spectroscopy techniques greatly benefit from ZMW and plasmonic antennas to enter a new dimension of molecular concentration reaching physiological conditions. The application of nano-optics to biological problems with FRET and FCS is an emerging and exciting field, and is promising to reveal new insights on biological functions and dynamics.

  20. Internet-based assessment of image sharpness enhancement

    NASA Astrophysics Data System (ADS)

    MacDonald, Lindsay; Bouzit, Samira

    2008-01-01

    Two internet-based psychophysical experiments were conducted to investigate the performance of an image sharpness enhancement method, based on adjustment of spatial frequencies in the image according to the contrast sensitivity function and compensation of MTF losses of the display. The method was compared with the widely-used unsharp mask (USM) filter from PhotoShop. The experiment was performed in two locations with different groups of observers: one in the UK, and the second in the USA. Three Apple LCD displays (15" studio, 23" HD cinema and 15" PowerBook) were used at both sites. Observers assessed the sharpness and pleasantness of the displayed images. Analysis of the results led to four major conclusions: (1) Performance of the sharpening methods; (2) Influence of MTF compensation; (3) Image dependency; and (4) Comparison between sharpness perception and preference judgement at both sites.

  1. Enhanced Weight based DSR for Mobile Ad Hoc Networks

    NASA Astrophysics Data System (ADS)

    Verma, Samant; Jain, Sweta

    2011-12-01

    Routing in ad hoc network is a great problematic, since a good routing protocol must ensure fast and efficient packet forwarding, which isn't evident in ad hoc networks. In literature there exists lot of routing protocols however they don't include all the aspects of ad hoc networks as mobility, device and medium constraints which make these protocols not efficient for some configuration and categories of ad hoc networks. Thus in this paper we propose an improvement of Weight Based DSR in order to include some of the aspects of ad hoc networks as stability, remaining battery power, load and trust factor and proposing a new approach Enhanced Weight Based DSR.

  2. Enhancing interprofessional student practice through a case-based model.

    PubMed

    Cahill, Mairead; O'Donnell, Marie; Warren, Alison; Taylor, Ann; Gowan, Olive

    2013-07-01

    Healthcare workers are increasingly being called upon to work collaboratively in practice to improve patient care and it seems imperative that interprofessional working should be mirrored in student education, especially during placements. This short report describes a qualitative evaluation of a client-centered, case-based model of interprofessional education (IPE) which aimed to improve interprofessional communication and team working skills for the students and therapists involved in practice placements. The IPE project implemented the meet, assess, goal set, plan, implement, evaluate (MAGPIE) framework for interprofessional case-based teaching (Queensland-Health (2008)) alongside the International Classification of Function, Disability and Health (ICF) (WHO, 2001). Three separate focus groups explored the experiences of the students, therapists and placement facilitators from the disciplines of occupational therapy, physiotherapy and speech and language therapy. Three themes emerged: IPE as a motivating experience, IPE enhancing the depth of learning and clarity of expectations. This report concluded that IPE in the clinical setting, using the client-centered MAGPIE model, provided a strong foundation for enhanced learning in practice education contexts. PMID:23398325

  3. Detail enhancement of blurred infrared images based on frequency extrapolation

    NASA Astrophysics Data System (ADS)

    Xu, Fuyuan; Zeng, Deguo; Zhang, Jun; Zheng, Ziyang; Wei, Fei; Wang, Tiedan

    2016-05-01

    A novel algorithm for enhancing the details of the blurred infrared images based on frequency extrapolation has been raised in this paper. Unlike other researchers' work, this algorithm mainly focuses on how to predict the higher frequency information based on the Laplacian pyramid separation of the blurred image. This algorithm uses the first level of the high frequency component of the pyramid of the blurred image to reverse-generate a higher, non-existing frequency component, and adds back to the histogram equalized input blurred image. A simple nonlinear operator is used to analyze the extracted first level high frequency component of the pyramid. Two critical parameters are participated in the calculation known as the clipping parameter C and the scaling parameter S. The detailed analysis of how these two parameters work during the procedure is figure demonstrated in this paper. The blurred image will become clear, and the detail will be enhanced due to the added higher frequency information. This algorithm has the advantages of computational simplicity and great performance, and it can definitely be deployed in the real-time industrial applications. We have done lots of experiments and gave illustrations of the algorithm's performance in this paper to convince its effectiveness.

  4. Prism-based single-camera system for stereo display

    NASA Astrophysics Data System (ADS)

    Zhao, Yue; Cui, Xiaoyu; Wang, Zhiguo; Chen, Hongsheng; Fan, Heyu; Wu, Teresa

    2016-06-01

    This paper combines the prism and single camera and puts forward a method of stereo imaging with low cost. First of all, according to the principle of geometrical optics, we can deduce the relationship between the prism single-camera system and dual-camera system, and according to the principle of binocular vision we can deduce the relationship between binoculars and dual camera. Thus we can establish the relationship between the prism single-camera system and binoculars and get the positional relation of prism, camera, and object with the best effect of stereo display. Finally, using the active shutter stereo glasses of NVIDIA Company, we can realize the three-dimensional (3-D) display of the object. The experimental results show that the proposed approach can make use of the prism single-camera system to simulate the various observation manners of eyes. The stereo imaging system, which is designed by the method proposed by this paper, can restore the 3-D shape of the object being photographed factually.

  5. Single-step, paper-based concentration and detection of a malaria biomarker.

    PubMed

    Pereira, David Y; Chiu, Ricky Y T; Zhang, Samantha C L; Wu, Benjamin M; Kamei, Daniel T

    2015-07-01

    The lateral-flow immunoassay (LFA) is an inexpensive and rapid paper-based assay that can potentially detect infectious disease biomarkers in resource-poor settings. Despite its many advantages that make it suitable for point-of-care diagnosis, LFA is limited by its inferior sensitivity relative to sophisticated laboratory-based assays. Our group previously introduced the use of a micellar aqueous two-phase system (ATPS), comprised of the nonionic Triton X-114 surfactant, to concentrate biomarkers in a sample and enhance their detection with LFA. However, achieving complete phase separation and target concentration using the Triton X-114 system required many hours, and the concentrated sample needed to be manually extracted and applied to LFA. Here, we successfully integrated the concentration and detection steps into a single step that occurs entirely within a portable paper-based diagnostic strip. In a novel approach, we applied the micellar ATPS to a 3-D paper design and effectively reduced the macroscopic phase separation time from 8 h to approximately 3 min. The 3-D design was integrated with LFA to simultaneously concentrate and detect Plasmodium lactate dehydrogenase (pLDH), a malaria biomarker, in both phosphate-buffered saline and fetal bovine serum within 20 min at room temperature. Compared to a conventional LFA setup with a pLDH detection limit of 10 ng μL(-1), our single-step diagnostic successfully detected pLDH at 1.0 ng μL(-1), demonstrating a 10-fold detection limit improvement and resulting in a sensitive and user-friendly assay that can be used at the point-of-care. The integration of a micellar ATPS and LFA represents a new platform that can improve and promote the use of paper-based diagnostic assays for malaria and other diseases within resource-poor settings.

  6. Giant enhancement in critical current density, up to a hundredfold, in superconducting NaFe0.97Co0.03 As single crystals under hydrostatic pressure

    PubMed Central

    Shabbir, Babar; Wang, Xiaolin; Ghorbani, S. R.; Wang, A. F.; Dou, Shixue; Chen, X. H.

    2015-01-01

    Tremendous efforts towards improvement in the critical current density “Jc” of iron based superconductors (FeSCs), especially at relatively low temperatures and magnetic fields, have been made so far through different methods, resulting in real progress. Jc at high temperatures in high fields still needs to be further improved, however, in order to meet the requirements of practical applications. Here, we demonstrate a simple approach to achieve this. Hydrostatic pressure can significantly enhance Jc in NaFe0.97Co0.03As single crystals by at least tenfold at low field and more than a hundredfold at high fields. Significant enhancement in the in-field performance of NaFe0.97Co0.03As single crystal in terms of pinning force density (Fp) is found at high pressures. At high fields, the Fp is over 20 and 80 times higher than under ambient pressure at12 K and 14 K, respectively, at P = 1 GPa. We believe that the Co-doped NaFeAs compounds are very exciting and deserve to be more intensively investigated. Finally, it is worthwhile to say that by using hydrostatic pressure, we can achieve more milestones in terms of high Jc values in tapes, wires or films of other Fe-based superconductors. PMID:26030085

  7. Epitaxial lift-off of quantum dot enhanced GaAs single junction solar cells

    SciTech Connect

    Bennett, Mitchell F.; Bittner, Zachary S.; Forbes, David V.; Hubbard, Seth M.; Rao Tatavarti, Sudersena; Wibowo, Andree; Pan, Noren; Chern, Kevin; Phillip Ahrenkiel, S.

    2013-11-18

    InAs/GaAs strain-balanced quantum dot (QD) n-i-p solar cells were fabricated by epitaxial lift-off (ELO), creating thin and flexible devices that exhibit an enhanced sub-GaAs bandgap current collection extending into the near infrared. Materials and optical analysis indicates that QD quality after ELO processing is preserved, which is supported by transmission electron microscopy images of the QD superlattice post-ELO. Spectral responsivity measurements depict a broadband resonant cavity enhancement past the GaAs bandedge, which is due to the thinning of the device. Integrated external quantum efficiency shows a QD contribution to the short circuit current density of 0.23 mA/cm{sup 2}.

  8. Indium plasma in single- and two-color mid-infrared fields: Enhancement of tunable harmonics

    NASA Astrophysics Data System (ADS)

    Ganeev, R. A.; Wang, Zhe; Lan, Pengfei; Lu, Peixiang; Suzuki, M.; Kuroda, H.

    2016-04-01

    The tuning of odd and even high-order harmonics of ultrashort pulses along the strong resonance of laser-produced indium plasma using an optical parametric amplifier of white-light continuum radiation (1250-1400 nm) allowed observation of different harmonics enhanced in the vicinity of the 4 d105 s21S0→4 d95 s25 p 1P1 transition of In ii ions. We demonstrate various peculiarities and discuss the theoretical model of the phenomenon of tunable harmonics enhancement in the region of 62 nm using indium plasma. With the theoretical analysis we can reproduce the experimental observations and characterize the dynamics of the resonant harmonic emissions.

  9. Enhanced photoluminescence from self-organized rubrene single crystal surface structures

    NASA Astrophysics Data System (ADS)

    Stöhr, R. J.; Beirne, G. J.; Michler, P.; Scholz, R.; Wrachtrup, J.; Pflaum, J.

    2010-06-01

    We report on crystalline pyramidal structures grown via self-organization on the rubrene (001) surface. The analysis of their spectral response by means of photoluminescence with micrometer lateral resolution reveals an intensity enhancement on-top of the surface structures. As we demonstrate this intensity increase can be related to the excitation processes at the molecular level in combination with exciton confinement within the pyramids.

  10. Single molecule fluorescence studies of ribosome dynamics: An application of metal enhanced fluorescence

    NASA Astrophysics Data System (ADS)

    Bharill, Shashank

    Metal enhanced fluorescence (MEF), in which a surface plasmon near a noble metal alters the spectral properties of an organic fluorophore, has been reported to increase fluorescence intensity without a concomitant increase in photobleaching rate. The fluorescence intensities of Cy3- and Cy5-labeled ribosomal initiation complexes (ICs) near 50 nm silver particles were increased 4 - 7-fold compared to ICs in the absence of silver colloids. Photobleaching lifetime was not significantly decreased, resulting in 4 - 5.5-fold enhancement in total photon emission prior to photobleaching. Fluorophores showing enhanced fluorescence were located within ˜280 nm of the colloidal particles, as detected by light scattering and scanning probe microscopy. Aggregates of silver particles or larger colloids themselves produced wavelength-shifted luminescence similar to fluorescence, presumably due to resonant extinction between nearby metal particles. Intensity fluctuations above shot noise, at 0.1 - 5 Hz, were greater from slides containing colloidal particles than from plain glass. Overall signal to noise ratio was similar or slightly better near the silver particles. Proximity to silver particles did not compromise ribosome function, as measured by codon-dependent binding of fluorescent tRNA to the A site of fluorescent labeled ribosomes, dynamics of fluorescence resonance energy transfer between adjacent tRNAs in the ribosomal A and P sites, and elongation factor G catalyzed translocation.

  11. Efficiency enhancement in a single-pass Raman free electron laser

    SciTech Connect

    Rouhani, M. H.; Maraghechi, B.

    2009-09-15

    Efficiency enhancement in free electron laser (FEL) with ion channel and axial magnetic field is compared. By using Maxwell's equations and nonwiggler averaged equation of motion of electron beam, a set of coupled nonlinear differential equations is derived in the slowly varying amplitude and wave number approximation. Because of using nonwiggler averaged equation of motion, it is possible to treat the injection of the beam into the wiggler. The electron beam propagates with a relativistic velocity, ions are assumed immobile and slippage is ignored. The final set of nonlinear first-order differential equations describing the nonlinear evolution of the FEL is solved by the Runge-Kutta method. Efficiency enhancement in group I orbits is almost the same for both ion channel and axial magnetic field cases, with somewhat larger growth rate for the latter. In group II orbits, efficiency enhancement is not possible for the ion-channel guiding; however, the intrinsic efficiency can be larger than that of the axial magnetic field case.

  12. Large Grained Perovskite Solar Cells Derived from Single-Crystal Perovskite Powders with Enhanced Ambient Stability.

    PubMed

    Yen, Hung-Ju; Liang, Po-Wei; Chueh, Chu-Chen; Yang, Zhibin; Jen, Alex K-Y; Wang, Hsing-Lin

    2016-06-15

    In this study, we demonstrate the large grained perovskite solar cells prepared from precursor solution comprising single-crystal perovskite powders for the first time. The resultant large grained perovskite thin film possesses a negligible physical (structural) gap between each large grain and is highly crystalline as evidenced by its fan-shaped birefringence observed under polarized light, which is very different from the thin film prepared from the typical precursor route (MAI + PbI2).

  13. Brightness-enhanced high-efficiency single emitters for fiber laser pumping

    NASA Astrophysics Data System (ADS)

    Yanson, Dan; Rappaport, Noam; Shamay, Moshe; Cohen, Shalom; Berk, Yuri; Klumel, Genadi; Don, Yaroslav; Peleg, Ophir; Levy, Moshe

    2013-02-01

    Reliable single emitters delivering <10W in the 9xx nm spectral range, are common energy sources for fiber laser pumps. The brightness (radiance) of a single emitter, which connotes the angular concentration of the emitted energy, is just as important a parameter as the output power alone for fiber coupling applications. We report on the development of high-brightness single emitters that demonstrate <12W output with 60% wall-plug efficiency and a lateral emission angle that is compatible with coupling into 0.15 NA delivery fiber. Using a purpose developed active laser model, simulation of far-field patterns in the lateral (slow) axis can be performed for different epitaxial wafer structures. By optimizing both the wafer and chip designs, we have both increased the device efficiency and improved the slow-axis divergence in high-current operation. Device reliability data are presented. The next-generation emitters will be integrated in SCD's NEON fiber pump modules to upgrade the pump output towards higher ex-fiber powers with high efficiency.

  14. Convergence enhancement of single-pixel PIV with symmetric double correlation

    NASA Astrophysics Data System (ADS)

    Avallone, Francesco; Discetti, Stefano; Astarita, Tommaso; Cardone, Gennaro

    2015-04-01

    A symmetric correlation approach is proposed to improve the convergence of the single-pixel technique for particle image velocimetry (PIV). Nogueira et al. (Exp Fluids 30:309-316, 2001) introduced this method to remove a source of random errors in PIV when small interrogation windows are used; it consists in applying the cross-correlation operator by considering fixed the first exposure and moving the second one, and vice versa, and then calculating the cross-correlation map as the average of the two maps. The symmetric correlation suppresses the effects of truncation of the particles lying on the border of the interrogation windows. In this paper, the application of symmetric correlation to single-pixel PIV algorithms is reported. Since symmetric direct correlation provides a significant improvement in the cross-correlation peak shape with respect to the standard asymmetric single-pixel implementation, a faster convergence in estimating the average velocity components and turbulence statistics is achieved. An additional improvement is due to the possibly limited correlation between the background noise for the two exposures. The algorithm is tested via synthetic images with imposed constant and sinusoidal displacement and then tested with real data of a jet flow. The technique has shown that the same accuracy of the standard asymmetric approach can be achieved with 50 % of the samples and that a reduction in the measurement error by 30 % is obtained when using the same number of samples.

  15. Enhanced Macroscopic Quantum Tunneling in Capacitively Coupled BiPb2201 Single-Layered Intrinsic Josephson Junctions

    NASA Astrophysics Data System (ADS)

    Nomura, Yoshiki; Mizuno, Takaaki; Kambara, Hitoshi; Nakagawa, Yuya; Kakeya, Itsuhiro

    2015-01-01

    Macroscopic quantum tunneling (MQT) in an intrinsic Josephson junction (IJJ) stack of Bi1.9Pb0.1Sr1.39La0.63CuO6+δ (BiPb2201) has been investigated. For the first switch, from superconducting to the first resistive branch in current-voltage characteristics, the crossover between MQT and thermal activation (TA) takes place at 0.6 K. On the other hand, for the second switch, the MQT-TA crossover temperature is increased to 2.0 K. This result is interpreted as follows: the MQT rate of the second switch is enhanced by the charge coupling between adjacent IJJs as well as in Bi2Sr2CaCu2O8+δ. We consider that the enhancement of the MQT rate is a common feature among bismuth-cuprates with single and double CuO2 layers in their crystal structures.

  16. Single plasma mirror providing 104 contrast enhancement and 70% reflectivity for intense femtosecond lasers.

    PubMed

    Inoue, Shunsuke; Maeda, Kazuya; Tokita, Shigeki; Mori, Kazuaki; Teramoto, Kensuke; Hashida, Masaki; Sakabe, Shuji

    2016-07-20

    To efficiently eliminate picosecond pre-pulses that accompany ultrashort pulses emitted from high-power chirped-pulse-amplification laser systems, we have developed a high-performance plasma mirror system. By reducing the reflectivity of the antireflection coating on the substrate for the plasma mirror to the limit of current technology (∼0.006%), we achieved the highest pre-pulse contrast enhancement reported to date for a single plasma mirror of 104 at 1 ps before the pulse peak. By optimizing the laser incidence to the plasma mirror and the laser fluence, the reflectivity of the plasma mirror has been improved to 70%. The contrast improvement indicates extensibility to 100 PW class lasers by doubling this plasma mirror system. Contrast enhancement of 108 should be possible without a serious reduction in energy (no more than 50%). PMID:27463920

  17. Enhancement of ambipolar characteristics in single-walled carbon nanotubes using C{sub 60} and fabrication of logic gates

    SciTech Connect

    Park, Steve; Nam, Ji Hyun; Koo, Ja Hoon; Lei, Ting; Bao, Zhenan

    2015-03-09

    We demonstrate a technique to convert p-type single-walled carbon nanotube (SWNT) network transistor into ambipolar transistor by thermally evaporating C{sub 60} on top. The addition of C{sub 60} was observed to have two effects in enhancing ambipolar characteristics. First, C{sub 60} served as an encapsulating layer that enhanced the ambipolar characteristics of SWNTs. Second, C{sub 60} itself served as an electron transporting layer that contributed to the n-type conduction. Such a dual effect enables effective conversion of p-type into ambipolar characteristics. We have fabricated inverters using our SWNT/C{sub 60} ambipolar transistors with gain as high as 24, along with adaptive NAND and NOR logic gates.

  18. Enhanced Photoelectrical Response of Hydrogenated Amorphous Silicon Single-Nanowire Solar Cells by Front-Opening Crescent Design

    NASA Astrophysics Data System (ADS)

    Yang, Zhenhai; Cao, Guoyang; Shang, Aixue; Lei, Dang Yuan; Zhang, Cheng; Gao, Pingqi; Ye, Jichun; Li, Xiaofeng

    2016-04-01

    We report an approach for substantially enhancing the light-trapping and photoconversion efficiency of hydrogenated amorphous silicon (a-Si:H) single-nanowire solar cells (SNSCs) by engineering the cross section of the nanowire from circular into a front-opening crescent shape. The proposed SNSCs show a broadband and highly tunable optical absorption compared to the conventional circular counterparts under both transverse electric and transverse magnetic incidences, enabling an enhancement ratio of over 40 % in both the photocurrent density and the photoconversion efficiency in a-Si:H SNSCs with a diameter of 200 nm. We further show that the superior performance can be well maintained under a wide range of incident angle and is robust to the blunt crescent edges.

  19. Enhanced Photoelectrical Response of Hydrogenated Amorphous Silicon Single-Nanowire Solar Cells by Front-Opening Crescent Design.

    PubMed

    Yang, Zhenhai; Cao, Guoyang; Shang, Aixue; Lei, Dang Yuan; Zhang, Cheng; Gao, Pingqi; Ye, Jichun; Li, Xiaofeng

    2016-12-01

    We report an approach for substantially enhancing the light-trapping and photoconversion efficiency of hydrogenated amorphous silicon (a-Si:H) single-nanowire solar cells (SNSCs) by engineering the cross section of the nanowire from circular into a front-opening crescent shape. The proposed SNSCs show a broadband and highly tunable optical absorption compared to the conventional circular counterparts under both transverse electric and transverse magnetic incidences, enabling an enhancement ratio of over 40 % in both the photocurrent density and the photoconversion efficiency in a-Si:H SNSCs with a diameter of 200 nm. We further show that the superior performance can be well maintained under a wide range of incident angle and is robust to the blunt crescent edges. PMID:27129685

  20. Enhanced Photoelectrical Response of Hydrogenated Amorphous Silicon Single-Nanowire Solar Cells by Front-Opening Crescent Design.

    PubMed

    Yang, Zhenhai; Cao, Guoyang; Shang, Aixue; Lei, Dang Yuan; Zhang, Cheng; Gao, Pingqi; Ye, Jichun; Li, Xiaofeng

    2016-12-01

    We report an approach for substantially enhancing the light-trapping and photoconversion efficiency of hydrogenated amorphous silicon (a-Si:H) single-nanowire solar cells (SNSCs) by engineering the cross section of the nanowire from circular into a front-opening crescent shape. The proposed SNSCs show a broadband and highly tunable optical absorption compared to the conventional circular counterparts under both transverse electric and transverse magnetic incidences, enabling an enhancement ratio of over 40 % in both the photocurrent density and the photoconversion efficiency in a-Si:H SNSCs with a diameter of 200 nm. We further show that the superior performance can be well maintained under a wide range of incident angle and is robust to the blunt crescent edges.

  1. Single-shot thermometry and OH detection via femtosecond fully resonant electronically enhanced CARS (FREE-CARS).

    PubMed

    Wrzesinski, Paul J; Stauffer, Hans U; Schmidt, Jacob B; Roy, Sukesh; Gord, James R

    2016-05-01

    Femtosecond time-resolved, fully resonant electronically enhanced coherent anti-Stokes Raman scattering (FREE-CARS) spectroscopy, incorporating a two-color excitation scheme, is used to demonstrate selective and sensitive gas-phase detection of the hydroxyl (OH) radical in a reacting flow. Spectral resolution of the emitted FREE-CARS signal allows simultaneous detection of temperature and relative OH mole fraction under single-laser-shot conditions in a laminar ethylene-air flame. By comparison to previously reported OH concentration and temperature measurements, we demonstrate excellent single-shot temperature accuracies (∼2% deviation from adiabatic flame temperature) and precisions (∼2% standard deviation), with simultaneous relative OH concentration measurements that demonstrate high detection sensitivity (100-300 ppm). PMID:27128064

  2. Enhanced magnetic anisotropies of single transition-metal adatoms on a defective MoS2 monolayer.

    PubMed

    Cong, W T; Tang, Z; Zhao, X G; Chu, J H

    2015-03-23

    Single magnetic atoms absorbed on an atomically thin layer represent the ultimate limit of bit miniaturization for data storage. To approach the limit, a critical step is to find an appropriate material system with high chemical stability and large magnetic anisotropic energy. Here, on the basis of first-principles calculations and the spin-orbit coupling theory, it is elucidated that the transition-metal Mn and Fe atoms absorbed on disulfur vacancies of MoS2 monolayers are very promising candidates. It is analysed that these absorption systems are of not only high chemical stabilities but also much enhanced magnetic anisotropies and particularly the easy magnetization axis is changed from the in-plane one for Mn to the out-of-plane one for Fe by a symmetry-lowering Jahn-Teller distortion. The results point out a promising direction to achieve the ultimate goal of single adatomic magnets with utilizing the defective atomically thin layers.

  3. Enhanced Magnetic Anisotropies of Single Transition-Metal Adatoms on a Defective MoS2 Monolayer

    PubMed Central

    Cong, W. T.; Tang, Z.; Zhao, X. G.; Chu, J. H.

    2015-01-01

    Single magnetic atoms absorbed on an atomically thin layer represent the ultimate limit of bit miniaturization for data storage. To approach the limit, a critical step is to find an appropriate material system with high chemical stability and large magnetic anisotropic energy. Here, on the basis of first-principles calculations and the spin-orbit coupling theory, it is elucidated that the transition-metal Mn and Fe atoms absorbed on disulfur vacancies of MoS2 monolayers are very promising candidates. It is analysed that these absorption systems are of not only high chemical stabilities but also much enhanced magnetic anisotropies and particularly the easy magnetization axis is changed from the in-plane one for Mn to the out-of-plane one for Fe by a symmetry-lowering Jahn-Teller distortion. The results point out a promising direction to achieve the ultimate goal of single adatomic magnets with utilizing the defective atomically thin layers. PMID:25797135

  4. Enhanced photodegradation of pentachlorophenol by single and mixed nonionic and anionic surfactants using graphene-TiO₂ as catalyst.

    PubMed

    Zhang, Yaxin; He, Xin; Zeng, Guangming; Chen, Tan; Zhou, Zeyu; Wang, Hongtao; Lu, Wenjing

    2015-11-01

    The photodegradation of pentachlorophenol (PCP) in a surfactant-containing (single and mixed) complex system using graphene-TiO2 (GT) as catalyst was investigated. The objective was to better understand the behavior of surfactants in a GT catalysis system for its possible use in remediation technology of soil contaminated by hydrophobic organic compounds (HOCs). In a single-surfactant system, surfactant molecules aggregated on GT via hydrogen bonding and electrostatic force; nonideal mixing between nonionic and anionic surfactants rendered GT surface with mixed admicelles in a mixed surfactant system. Both effects helped incorporating PCP molecules into surfactant aggregates on catalyst surface. Hence, the targeted pollutants were rendered easily available to photo-yielded oxidative radicals, and photodegradation efficiency was significantly enhanced. Finally, real soil washing-photocatalysis trials proved that anionic-nonionic mixed surfactant soil washing coupled with graphene-TiO2 photocatalysis can be one promising technology for HOC-polluted soil remediation. PMID:26194233

  5. Single-nucleotide polymorphisms and activity analysis of the promoter and enhancer of the pig lactase gene.

    PubMed

    Du, Hai-Ting; Zhu, Hong-Yan; Wang, Jia-Mei; Zhao, Wei; Tao, Xiao-Li; Ba, Cai-Feng; Tian, Yu-Min; Su, Yu-Hong

    2014-07-15

    Lactose intolerance in northern Europeans is strongly associated with a single-nucleotide polymorphism (SNP) located 14 kb upstream of the human lactase gene: -13,910 C/T. We examined whether SNPs in the 5' flanking region of the pig lactase gene are similar to those in the human gene and whether these polymorphisms play a functional role in regulating pig lactase gene expression. The 5' flanking region of the lactase gene from several different breeds of pigs was cloned and analyzed for gene regulatory activity of a luciferase reporter gene. One SNP was found in the enhancer region (-797 G/A) and two were found in the promoter region (-308G/C and -301 A/G). The promoter C-308,G-301(Pro-CG) strongly promotes the expression of the lactase gene, but the promoter G-308,A-301(Pro-GA) does not. The enhancer A-797(Enh-A) genotype for Pro-GA can significantly enhance promoter activity, but has an inhibitory effect on Pro-CG. The Enhancer G-797(Enh-G) has a significant inhibitory effect on both promoters. In conclusion, the order of effectiveness on the pig lactase gene is Enh-A+Pro-GA>Enh-A/G+Pro-CG>Enh-G+Pro-GA.

  6. Dendrimer-templated Fe nanoparticles for the growth of single-wall carbon nanotubes by plasma-enhanced CVD.

    PubMed

    Amama, Placidus B; Maschmann, Matthew R; Fisher, Timothy S; Sands, Timothy D

    2006-06-01

    A fourth-generation (G4) poly(amidoamine) (PAMAM) dendrimer (G4-NH2) has been used as a template to deliver nearly monodispersed catalyst nanoparticles to SiO2/Si, Ti/Si, sapphire, and porous anodic alumina (PAA) substrates. Fe2O3 nanoparticles obtained after calcination of the immobilized Fe3+/G4-NH2 composite served as catalytic "seeds" for the growth of single-wall carbon nanotubes (SWNTs) by microwave plasma-enhanced CVD (PECVD). To surmount the difficulty associated with SWNT growth via PECVD, reaction conditions that promote the stabilization of Fe nanoparticles, resulting in enhanced SWNT selectivity and quality, have been identified. In particular, in situ annealing of Fe catalyst in an N2 atmosphere was found to improve SWNT selectivity and quality. H2 prereduction at 900 degrees C for 5 min was also found to enhance SWNT selectivity and quality for SiO2/Si supported catalyst, albeit of lower quality for sapphire supported catalyst. The application of positive dc bias voltage (+200 V) during SWNT growth was shown to be very effective in removing amorphous carbon impurities while enhancing graphitization, SWNT selectivity, and vertical alignment. The results of this study should promote the use of exposed Fe nanoparticles supported on different substrates for the growth of high-quality SWNTs by PECVD. PMID:16771309

  7. Single-nucleotide polymorphisms and activity analysis of the promoter and enhancer of the pig lactase gene.

    PubMed

    Du, Hai-Ting; Zhu, Hong-Yan; Wang, Jia-Mei; Zhao, Wei; Tao, Xiao-Li; Ba, Cai-Feng; Tian, Yu-Min; Su, Yu-Hong

    2014-07-15

    Lactose intolerance in northern Europeans is strongly associated with a single-nucleotide polymorphism (SNP) located 14 kb upstream of the human lactase gene: -13,910 C/T. We examined whether SNPs in the 5' flanking region of the pig lactase gene are similar to those in the human gene and whether these polymorphisms play a functional role in regulating pig lactase gene expression. The 5' flanking region of the lactase gene from several different breeds of pigs was cloned and analyzed for gene regulatory activity of a luciferase reporter gene. One SNP was found in the enhancer region (-797 G/A) and two were found in the promoter region (-308G/C and -301 A/G). The promoter C-308,G-301(Pro-CG) strongly promotes the expression of the lactase gene, but the promoter G-308,A-301(Pro-GA) does not. The enhancer A-797(Enh-A) genotype for Pro-GA can significantly enhance promoter activity, but has an inhibitory effect on Pro-CG. The Enhancer G-797(Enh-G) has a significant inhibitory effect on both promoters. In conclusion, the order of effectiveness on the pig lactase gene is Enh-A+Pro-GA>Enh-A/G+Pro-CG>Enh-G+Pro-GA. PMID:24809963

  8. Superconducting detector of IR single-photons based on thin WSi films

    NASA Astrophysics Data System (ADS)

    Seleznev, V. A.; Divochiy, A. V.; Vakhtomin, Yu B.; Morozov, P. V.; Zolotov, P. I.; Vasil'ev, D. D.; Moiseev, K. M.; Malevannaya, E. I.; Smirnov, K. V.

    2016-08-01

    We have developed the deposition technology of WSi thin films 4 to 9 nm thick with high temperature values of superconducting transition (Tc~4 K). Based on deposed films there were produced nanostructures with indicative planar sizes ~100 nm, and the research revealed that even on nanoscale the films possess of high critical temperature values of the superconducting transition (Tc~3.3-3.7 K) which certifies high quality and homogeneity of the films created. The first experiments on creating superconducting single-photon detectors showed that the detectors’ SDE (system detection efficiency) with increasing bias current (I b) reaches a constant value of ~30% (for X=1.55 micron) defined by infrared radiation absorption by the superconducting structure. To enhance radiation absorption by the superconductor there were created detectors with cavity structures which demonstrated a practically constant value of quantum efficiency >65% for bias currents Ib>0.6-Ic. The minimal dark counts level (DC) made 1 s-1 limited with background noise. Hence WSi is the most promising material for creating single-photon detectors with record SDE/DC ratio and noise equivalent power (NEP).

  9. Mechanical and Electrical Properties of a Polyimide Film Significantly Enhanced by the Addition of Single-Wall Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Meador, Michael A.

    2005-01-01

    Single-wall carbon nanotubes have been shown to possess a combination of outstanding mechanical, electrical, and thermal properties. The use of carbon nanotubes as an additive to improve the mechanical properties of polymers and/or enhance their thermal and electrical conductivity has been a topic of intense interest. Nanotube-modified polymeric materials could find a variety of applications in NASA missions including large-area antennas, solar arrays, and solar sails; radiation shielding materials for vehicles, habitats, and extravehicular activity suits; and multifunctional materials for vehicle structures and habitats. Use of these revolutionary materials could reduce vehicle weight significantly and improve vehicle performance and capabilities.

  10. Averaging of Replicated Pulses for Enhanced-Dynamic-Range Single-Shot Measurement of Nanosecond Optical Pulses

    SciTech Connect

    Marciante, J.R.; Donaldson, W.R.; Roides, R.G.

    2007-10-04

    Measuring optical pulse shapes beyond the dynamic range of oscilloscopes is achieved by temporal pulse stacking in a low-loss, passive, fiber-optic network. Optical pulses are averaged with their time-delayed replicas without introducing additional noise or jitter, allowing for high-contrast pulse-shape measurements of single-shot events. A dynamic-range enhancement of three bits is experimentally demonstrated and compared with conventional multi-shot averaging. This technique can be extended to yield an increase of up to seven bits of additional dynamic range over nominal oscilloscope performance.

  11. Silver-Gold Nanocomposite Substrates for Metal-Enhanced Fluorescence: Ensemble and Single-Molecule Spectroscopic Studies.

    PubMed

    Choudhury, Sharmistha Dutta; Badugu, Ramachandram; Ray, Krishanu; Lakowicz, Joseph R

    2012-03-01

    In recent years, there has been a growing interest in the studies involving the interactions of fluorophores with plasmonic nanostructures or nanoparticles. These interactions lead to several favorable effects such as increase in the fluorescence intensities, increased photostabilities, and reduced excited-state lifetimes that can be exploited to improve the capabilities of present fluorescence methodologies. In this regard, we report the use of newly developed silver-gold nanocomposite (Ag-Au-NC) structures as substrates for metal-enhanced fluorescence (MEF). The Ag-Au-NC substrates have been prepared by a one-step galvanic replacement reaction from thin silver films coated on glass slides. This approach is simple and suitable for the fabrication of MEF substrates with large area. We have observed about 15-fold enhancement in the fluorescence intensity of ATTO655 from ensemble fluorescence measurements using these substrates. The fluorescence enhancement on the Ag-Au-NC substrates is also accompanied by a reduction in the fluorescence lifetime of ATTO655, which is consistent with the fluorophore-plasmon coupling mechanism. Single-molecule fluorescence measurements have been performed to gain more insight into the metal-fluorophore interactions and to unravel the heterogeneity in the interaction of individual fluorophores with the fabricated substrates. The single-molecule studies are in good agreement with the ensemble measurements and show maximum enhancements of ~50-fold for molecules located in proximity to the "hotspots" on the substrates. In essence, the Ag-Au-NC substrates have a very good potential for various MEF applications.

  12. Silver–Gold Nanocomposite Substrates for Metal-Enhanced Fluorescence: Ensemble and Single-Molecule Spectroscopic Studies

    PubMed Central

    Choudhury, Sharmistha Dutta; Badugu, Ramachandram; Ray, Krishanu; Lakowicz, Joseph R.

    2012-01-01

    In recent years, there has been a growing interest in the studies involving the interactions of fluorophores with plasmonic nanostructures or nanoparticles. These interactions lead to several favorable effects such as increase in the fluorescence intensities, increased photostabilities, and reduced excited-state lifetimes that can be exploited to improve the capabilities of present fluorescence methodologies. In this regard, we report the use of newly developed silver–gold nanocomposite (Ag–Au–NC) structures as substrates for metal-enhanced fluorescence (MEF). The Ag–Au–NC substrates have been prepared by a one-step galvanic replacement reaction from thin silver films coated on glass slides. This approach is simple and suitable for the fabrication of MEF substrates with large area. We have observed about 15-fold enhancement in the fluorescence intensity of ATTO655 from ensemble fluorescence measurements using these substrates. The fluorescence enhancement on the Ag–Au–NC substrates is also accompanied by a reduction in the fluorescence lifetime of ATTO655, which is consistent with the fluorophore–plasmon coupling mechanism. Single-molecule fluorescence measurements have been performed to gain more insight into the metal–fluorophore interactions and to unravel the heterogeneity in the interaction of individual fluorophores with the fabricated substrates. The single-molecule studies are in good agreement with the ensemble measurements and show maximum enhancements of ~50-fold for molecules located in proximity to the “hotspots” on the substrates. In essence, the Ag–Au–NC substrates have a very good potential for various MEF applications. PMID:22707999

  13. Enhanced Single Seed Trait Predictions in Soybean (Glycine max) and Robust Calibration Model Transfer with Near-Infrared Reflectance Spectroscopy.

    PubMed

    Hacisalihoglu, Gokhan; Gustin, Jeffery L; Louisma, Jean; Armstrong, Paul; Peter, Gary F; Walker, Alejandro R; Settles, A Mark

    2016-02-10

    Single seed near-infrared reflectance (NIR) spectroscopy predicts soybean (Glycine max) seed quality traits of moisture, oil, and protein. We tested the accuracy of transferring calibrations between different single seed NIR analyzers of the same design by collecting NIR spectra and analytical trait data for globally diverse soybean germplasm. X-ray microcomputed tomography (μCT) was used to collect seed density and shape traits to enhance the number of soybean traits that can be predicted from single seed NIR. Partial least-squares (PLS) regression gave accurate predictive models for oil, weight, volume, protein, and maximal cross-sectional area of the seed. PLS models for width, length, and density were not predictive. Although principal component analysis (PCA) of the NIR spectra showed that black seed coat color had significant signal, excluding black seeds from the calibrations did not impact model accuracies. Calibrations for oil and protein developed in this study as well as earlier calibrations for a separate NIR analyzer of the same design were used to test the ability to transfer PLS regressions between platforms. PLS models built from data collected on one NIR analyzer had minimal differences in accuracy when applied to spectra collected from a sister device. Model transfer was more robust when spectra were trimmed from 910 to 1679 nm to 955-1635 nm due to divergence of edge wavelengths between the two devices. The ability to transfer calibrations between similar single seed NIR spectrometers facilitates broader adoption of this high-throughput, nondestructive, seed phenotyping technology.

  14. Localized tip enhanced Raman spectroscopic study of impurity incorporated single GaN nanowire in the sub-diffraction limit

    SciTech Connect

    Patsha, Avinash E-mail: dhara@igcar.gov.in; Dhara, Sandip; Tyagi, A. K.

    2015-09-21

    The localized effect of impurities in single GaN nanowires in the sub-diffraction limit is reported using the study of lattice vibrational modes in the evanescent field of Au nanoparticle assisted tip enhanced Raman spectroscopy (TERS). GaN nanowires with the O impurity and the Mg dopants were grown by the chemical vapor deposition technique in the catalyst assisted vapor-liquid-solid process. Symmetry allowed Raman modes of wurtzite GaN are observed for undoped and doped nanowires. Unusually very strong intensity of the non-zone center zone boundary mode is observed for the TERS studies of both the undoped and the Mg doped GaN single nanowires. Surface optical mode of A{sub 1} symmetry is also observed for both the undoped and the Mg doped GaN samples. A strong coupling of longitudinal optical (LO) phonons with free electrons, however, is reported only in the O rich single nanowires with the asymmetric A{sub 1}(LO) mode. Study of the local vibration mode shows the presence of Mg as dopant in the single GaN nanowires.

  15. Combined 3 Tesla MRI Biomarkers Improve the Differentiation between Benign vs Malignant Single Ring Enhancing Brain Masses

    PubMed Central

    Salice, Simone; Esposito, Roberto; Ciavardelli, Domenico; delli Pizzi, Stefano; di Bastiano, Rossella; Tartaro, Armando

    2016-01-01

    Purpose To evaluate whether the combination of imaging biomarkers obtained by means of different 3 Tesla (3T) Magnetic Resonance Imaging (MRI) advanced techniques can improve the diagnostic accuracy in the differentiation between benign and malignant single ring-enhancing brain masses. Materials and Methods 14 patients presenting at conventional 3T MRI single brain mass with similar appearance as regard ring enhancement, presence of peri-lesional edema and absence of hemorrhage signs were included in the study. All lesions were histologically proven: 5 pyogenic abscesses, 6 glioblastomas, and 3 metastases. MRI was performed at 3 Tesla and included Diffusion Weighted Imaging (DWI), Dynamic Susceptibility Contrast -Perfusion Weighted Imaging (DSC-PWI), Magnetic Resonance Spectroscopy (MRS), and Diffusion Tensor Imaging (DTI). Imaging biomarkers derived by those advanced techniques [Cerebral Blood Flow (CBF), relative Cerebral Blood Volume (rCBV), relative Main Transit Time (rMTT), Choline (Cho), Creatine (Cr), Succinate, N-Acetyl Aspartate (NAA), Lactate (Lac), Lipids, relative Apparent Diffusion Coefficient (rADC), and Fractional Anisotropy (FA)] were detected by two experienced neuroradiologists in joint session in 4 areas: Internal Cavity (IC), Ring Enhancement (RE), Peri-Lesional edema (PL), and Contralateral Normal Appearing White Matter (CNAWM). Significant differences between benign (n = 5) and malignant (n = 9) ring enhancing lesions were tested with Mann-Withney U test. The diagnostic accuracy of MRI biomarkers taken alone and MRI biomarkers ratios were tested with Receiver Operating Characteristic (ROC) analysis with an Area Under the Curve (AUC) ≥ 0.9 indicating a very good diagnostic accuracy of the variable. Results Five MRI biomarker ratios achieved excellent accuracy: IC-rADC/PL-NAA (AUC = 1), IC-rADC/IC-FA (AUC = 0.978), RE-rCBV/RE-FA (AUC = 0.933), IC-rADC/RE-FA (AUC = 0.911), and IC-rADC/PL-FA (AUC = 0.911). Only IC-rADC achieved a very good

  16. A realistic fabrication and design concept for quantum gates based on single emitters integrated in plasmonic-dielectric waveguide structures

    NASA Astrophysics Data System (ADS)

    Kewes, Günter; Schoengen, Max; Neitzke, Oliver; Lombardi, Pietro; Schönfeld, Rolf-Simon; Mazzamuto, Giacomo; Schell, Andreas W.; Probst, Jürgen; Wolters, Janik; Löchel, Bernd; Toninelli, Costanza; Benson, Oliver

    2016-07-01

    Tremendous enhancement of light-matter interaction in plasmonic-dielectric hybrid devices allows for non-linearities at the level of single emitters and few photons, such as single photon transistors. However, constructing integrated components for such devices is technologically extremely challenging. We tackle this task by lithographically fabricating an on-chip plasmonic waveguide-structure connected to far-field in- and out-coupling ports via low-loss dielectric waveguides. We precisely describe our lithographic approach and characterize the fabricated integrated chip. We find excellent agreement with rigorous numerical simulations. Based on these findings we perform a numerical optimization and calculate concrete numbers for a plasmonic single-photon transistor.

  17. A realistic fabrication and design concept for quantum gates based on single emitters integrated in plasmonic-dielectric waveguide structures.

    PubMed

    Kewes, Günter; Schoengen, Max; Neitzke, Oliver; Lombardi, Pietro; Schönfeld, Rolf-Simon; Mazzamuto, Giacomo; Schell, Andreas W; Probst, Jürgen; Wolters, Janik; Löchel, Bernd; Toninelli, Costanza; Benson, Oliver

    2016-01-01

    Tremendous enhancement of light-matter interaction in plasmonic-dielectric hybrid devices allows for non-linearities at the level of single emitters and few photons, such as single photon transistors. However, constructing integrated components for such devices is technologically extremely challenging. We tackle this task by lithographically fabricating an on-chip plasmonic waveguide-structure connected to far-field in- and out-coupling ports via low-loss dielectric waveguides. We precisely describe our lithographic approach and characterize the fabricated integrated chip. We find excellent agreement with rigorous numerical simulations. Based on these findings we perform a numerical optimization and calculate concrete numbers for a plasmonic single-photon transistor. PMID:27364604

  18. A realistic fabrication and design concept for quantum gates based on single emitters integrated in plasmonic-dielectric waveguide structures

    PubMed Central

    Kewes, Günter; Schoengen, Max; Neitzke, Oliver; Lombardi, Pietro; Schönfeld, Rolf-Simon; Mazzamuto, Giacomo; Schell, Andreas W.; Probst, Jürgen; Wolters, Janik; Löchel, Bernd; Toninelli, Costanza; Benson, Oliver

    2016-01-01

    Tremendous enhancement of light-matter interaction in plasmonic-dielectric hybrid devices allows for non-linearities at the level of single emitters and few photons, such as single photon transistors. However, constructing integrated components for such devices is technologically extremely challenging. We tackle this task by lithographically fabricating an on-chip plasmonic waveguide-structure connected to far-field in- and out-coupling ports via low-loss dielectric waveguides. We precisely describe our lithographic approach and characterize the fabricated integrated chip. We find excellent agreement with rigorous numerical simulations. Based on these findings we perform a numerical optimization and calculate concrete numbers for a plasmonic single-photon transistor. PMID:27364604

  19. Fracture of single crystals of the nickel-base superalloy PWA 1480E in hydrogen at 22 C

    NASA Technical Reports Server (NTRS)

    Chen, P. S.; Wilcox, R. C.

    1991-01-01

    The present study investigates the hydrogen-induced fracture behavior of notched single crystals of the PWA 1480E nickel-based superalloy. Notched single crystals with seven different crystal orientations were tensile tested at 22 C in a hydrogen atmosphere at 34 MPa. Hydrogen-enhanced cleavage along 100-line planes in the notched region was found to be due to cracking along the gamma/gamma-prime interfaces. Cleavage on 111-line-type planes was observed only outside the notch region. The occurrence of 100- and 111-line-types of cleavage was independent of the single-crystal orientation. Outside the notch region, the fracture surfaces of specimens tested in hydrogen appeared very similar to those tested in helium. Differences in the fracture surfaces were located primarily near the notch region.

  20. Gas cloud infrared image enhancement based on anisotropic diffusion

    NASA Astrophysics Data System (ADS)

    Li, Jiakun; Wang, Lingxue; Zhang, Changxing; Long, Yunting; Zhang, Bei

    2011-05-01

    Leakage of dangerous gases will not only pollute the environment, but also seriously threat public safety. Thermal infrared imaging has been proved to be an efficient method to qualitatively detect the gas leakage. But some problems are remained, especially when monitoring the leakage in a passive way. For example, the signal is weak and the edge of gas cloud in the infrared image is not obvious enough. However, we notice some important characteristics of the gas plume and therefore propose a gas cloud infrared image enhancement method based on anisotropic diffusion. As the gas plume presents a large gas cloud in the image and the gray value is even inside the cloud, strong forward diffusion will be used to reduce the noise and to expand the range of the gas cloud. Frames subtraction and K-means cluttering pop out the gas cloud area. Forward-and-Backward diffusion is to protect background details. Additionally, the best iteration times and the time step parameters are researched. Results show that the gas cloud can be marked correctly and enhanced by black or false color, and so potentially increase the possibility of gas leakage detection.

  1. HOW A SINGLE-POINT MUTATION IN HORSERADISH PEROXIDASE MARKEDLY ENHANCES ENANTIOSELECTIVITY

    PubMed Central

    Antipov, Eugene; Cho, Art E.; Klibanov, Alexander M.

    2009-01-01

    The effect of all possible mutations at position 178 on the enantioselectivity of yeast surface-bound horseradish peroxidase (HRP) toward chiral phenols has been investigated. In contrast to their wild-type predecessor, most HRP mutants are enantioselective, with the Arg178Glu variant exhibiting the greatest, 25-fold (S)/(R) preference. Using kinetic analysis of enzymatic oxidation of various substrate analogs and molecular modeling of enzyme-substrate complexes, this enantioselectivity enhancement is attributed to changes in the transition state energy due to electrostatic repulsion between the carboxylates of the enzyme's Glu178 and the substrate's (R)-enantiomer. PMID:19610634

  2. Cysticerci-related single parenchymal brain enhancing lesions in non-endemic countries

    PubMed Central

    Del Brutto, Oscar H.; Nash, Theodore E.; Garcia, Hector H.

    2012-01-01

    Objective Review of case reports and case series of patients with single cysticercus granulomas in non-endemic countries to determine the characteristics of this form of neurocysticercosis in these regions. Methods MEDLINE and manual search of patients with single cysticercus granulomas diagnosed in non-endemic countries from 1991 to 2011. Abstracted data included: demographic profile, clinical manifestations, form of neurocysticercosis, and whether the disease occurred in immigrants, international travelers, or citizens from non-endemic countries who had never been abroad. Results A total of 77 patients were found. Of these, 61 (79%) were diagnosed since the year 2000. Thirty-four patients (44%) patients were immigrants from endemic countries, 18 (23%) were international travelers returning from disease-endemic areas, and the remaining 25 (33%) were citizens from non-endemic countries who had never been abroad. Most immigrants and international travelers became symptomatic two or more years after returning home. Countries with the most reported patients were Kuwait (n=18), UK (n=11), Australia (n=8), USA (n=7), Japan (n=6), and Israel (n=5). Conclusions A single cerebral cysticercus granuloma in a non-endemic country is not a rare event. As seen in endemic regions, these cases have a good prognosis although more surgical procedures are performed in non-endemic countries, likely reflecting a decrease of diagnostic suspicion for cysticercosis and an increased availability of surgical options. The mean age of the reported cases was 25 years, and immigrants most often developed the disease greater than two years after arrival into a non-endemic area, suggesting a significant delay between infection and symptoms. However, some may have been infected and developed the disease while residing in non-endemic countries. PMID:22658897

  3. Counting rate enhancements in superconducting nanowire single-photon detectors with improved readout circuits.

    PubMed

    Zhao, Qingyuan; Jia, Tao; Gu, Min; Wan, Chao; Zhang, Labao; Xu, Weiwei; Kang, Lin; Chen, Jian; Wu, Peiheng

    2014-04-01

    Counting rates of superconducting nanowire single-photon detectors are usually estimated at hundreds of MHz by their kinetic-inductive reset time. This maximum is also limited by capacitor coupling effects in conventional readout circuits. In this Letter, we design and demonstrate an improved readout circuit that reduces the reset time and removes circuit limits. The counting rate at the 3 dB compression point is increased by four times for a large active area detector. We also discuss nonlinear dependences of the counting rate on the incident continuous-wave optical power and give a numerical model to explain our observations.

  4. Troika of single particle tracking programing: SNR enhancement, particle identification, and mapping.

    PubMed

    Shuang, Bo; Chen, Jixin; Kisley, Lydia; Landes, Christy F

    2014-01-14

    Single particle tracking (SPT) techniques provide a microscopic approach to probe in vivo and in vitro structure and reactions. Automatic analysis of SPT data with high efficiency and accuracy spurs the development of SPT algorithms. In this perspective, we review a range of available techniques used in SPT analysis programs. In addition, we present an example SPT program step-by-step to provide a guide so that researchers can use, modify, and/or write a SPT program for their own purposes. PMID:24263676

  5. Effect of single walled carbon nanotubes on the threshold voltage of dye based photovoltaic devices

    NASA Astrophysics Data System (ADS)

    Chakraborty, S.; Manik, N. B.

    2016-01-01

    Carbon nanotubes are being widely used in organic photovoltaic (OPV) devices as their usage has been reported to enhance the device efficiency along with other related parameters. In this work we have studied the energy (Ec) effect of single walled carbon nanotubes (SWCNT) on the threshold voltage (Vth) and also on the trap states of dye based photovoltaic devices. SWCNT is added in a series of dyes such as Rose Bengal (RB), Methyl Red (MR), Malachite Green (MG) and Crystal Violet (CV). By analysing the steady state dark current-voltage (I-V) characteristics Vth and Ec is estimated for the different devices with and without addition of SWCNT. It is observed that on an average for all the dyes Vth is reduced by about 30% in presence of SWCNT. The trap energy Ec also reduces in case of all the dyes. The relation between Vth, Ec and total trap density is discussed. From the photovoltaic measurements it is seen that the different photovoltaic parameters change with addition of SWCNT to the dye based devices. Both the short circuit current density and fill factor are found to increase for all the dye based devices in presence of SWCNT.

  6. Improving the Oxidation Resistance in Advanced Single Crystal Nickel-Based Superalloys for Turbine Applications

    SciTech Connect

    Alexander, K.B.; Kenik, E.A.; Miller, M.K.; Lin, L.S.; Cetel, A.D.

    1999-07-01

    The focus of this project was the examination of the role of yttrium and other alloying elements on the microstructure and oxidation performance of improved single crystal nickel-based superalloys for advanced turbine applications. The microstructure and microchemistry of both base and modified alloys and their surface oxides have been measured with state-of-the-art microanalytical techniques (atom probe field ion microscopy) and then correlated with identifying the partitioning behavior of the elemental additions in these superalloys before and after burner rig and engine-test oxidation performance. The overall technical goals included; (1) identifying the partitioning behavior of the elemental additions in these superalloys before and after burner rig and engine tests and the effect on the misfit energy between the phases in the alloys; (2) examining the oxidation performance of these newly-developed alloys; (3) identifying the influence of pre-oxidation processing on the subsequent oxidation performance; and (4) relating the microstructural and microchemical observations to the observed performance of these superalloys. The comparison of the base and modified alloys will produce a better understanding of the interaction between chemistry, structure, and performance in superalloys. In addition, it will lead to optimized alloys with improved performance including enhanced durability in the operating environments at the elevated temperature required to improve energy efficiency. The availability of alloys capable of higher temperature operation will minimize the need for expensive coatings in extreme temperature applications.

  7. Approaching the alloy limit of thermal conductivity in single-crystalline Si-based thermoelectric nanocomposites: A molecular dynamics investigation

    PubMed Central

    Guo, Ruiqiang; Huang, Baoling

    2015-01-01

    Single-crystalline Si-based nanocomposites have become promising candidates for thermoelectric applications due to their prominent merits. Reducing the thermal conductivity κ without deteriorating the electrical properties is the key to improve their performance. Through non-equilibrium molecular dynamics simulations, we show that κ of single-crystalline Si-based nanocomposites can be reduced to the alloy limit by embedding various nanoinclusions of similar lattice constants but different lattice orientations or space symmetries with respect to the matrix. The surprisingly low κ is mainly due to the large acoustic phonon density of states mismatch caused by the destruction of lattice periodicity at the interfaces between the nanoinclusions and matrix, which leads to the substantial reduction of phonon group velocity and relaxation time, as well as the enhancement of phonon localization. The resulting κ is also temperature-insensitive due to the dominance of boundary scattering. The increase in thermal resistance induced by lattice structure mismatch mainly comes from the nanoinclusions and the channels between them and is caused by the enhanced boundary scattering at the interfaces parallel to the heat flux. Approaching the alloy limit of κ with potentially improved electrical properties by fillers will remarkably improve ZT of single-crystalline Si-based nanocomposites and extend their application. PMID:25851401

  8. [Enhanced recovery after surgery based on medical ethics].

    PubMed

    Zhao, Qingchuan

    2016-03-01

    Enhanced recovery after surgery (ERAS), a new model of perioperative management developed in recent years, can shorten hospital stay, reduce medical cost and postoperative discomfort. However, some of these measures under the strategy are negation of the traditional recommendation and many surgeons are concerned about the medical tangle by the complications coming with the ERAS strategy. In this paper, ERAS strategy is evaluated from an ethical standpoint and the assessment factors of medical behavior are introduced based on medical virtues and medical ethnics. It is also analyzed that how to deal with the conflicts between the textbooks and the ERAS strategy, and elaborated that the medical ethics should be observed if the ERAS strategy is implemented. The scientific principles must be followed, the rights and interests of the patients need to be protected, and the informed consent should be guaranteed. PMID:27003639

  9. ESammon: A Computationaly Enhanced Sammon Mapping based on Data Density

    PubMed Central

    Wang, Chanpaul Jin; Fang, Hua; Wang, Honggang

    2016-01-01

    Sammon mapping is a widely used visualization technique to display complex data from high- to low-dimensional space. However, its extensive computational cost may pose potential computational challenges to big data visualization. This paper proposes a computationally-enhanced Sammon mapping (ESammon) by leveraging the characteristics of spatial data density. Unlike the conventional Sammon, ESammon preserves critical pairwise distances between data points in the process of projection, instead of all distances. Specifically, we integrated the Directed-Acyclic-Graph (DAG) based data density characterization method to select the critical distances. The numerical results demonstrated that our ESammon can achieve comparable projection results as the conventional Sammon mapping while reducing the computational cost from O(N2) to O(N).

  10. [Enhanced recovery after surgery based on medical ethics].

    PubMed

    Zhao, Qingchuan

    2016-03-01

    Enhanced recovery after surgery (ERAS), a new model of perioperative management developed in recent years, can shorten hospital stay, reduce medical cost and postoperative discomfort. However, some of these measures under the strategy are negation of the traditional recommendation and many surgeons are concerned about the medical tangle by the complications coming with the ERAS strategy. In this paper, ERAS strategy is evaluated from an ethical standpoint and the assessment factors of medical behavior are introduced based on medical virtues and medical ethnics. It is also analyzed that how to deal with the conflicts between the textbooks and the ERAS strategy, and elaborated that the medical ethics should be observed if the ERAS strategy is implemented. The scientific principles must be followed, the rights and interests of the patients need to be protected, and the informed consent should be guaranteed.

  11. Enhancing exposure-based therapy from a translational research perspective

    PubMed Central

    Hofmann, Stefan G.

    2007-01-01

    Combining an effective psychological treatment with conventional anxiolytic medication is typically not more effective than unimodal therapy for treating anxiety disorders. However, recent advances in the neuroscience of fear reduction have led to novel approaches for combining psychological therapy and pharmacological agents. Exposure-based treatments in humans partly rely on extinction to reduce the fear response in anxiety disorders. Animal studies have shown that d-cycloserine (DCS), a partial agonist at the glycine recognition site of the glutamatergic N-methyl- d-aspartate receptor facilitates extinction learning. Similarly, recent human trials have shown that DCS enhances fear reduction during exposure therapy of some anxiety disorders. This article discusses the biological and psychological mechanisms of extinction learning and the therapeutic value of DCS as an augmentation strategy for exposure therapy. Areas of future research will be identified. PMID:17659253

  12. Detection of explosives based on surface-enhanced Raman spectroscopy.

    PubMed

    Wackerbarth, Hainer; Salb, Christian; Gundrum, Lars; Niederkrüger, Matthias; Christou, Konstantin; Beushausen, Volker; Viöl, Wolfgang

    2010-08-10

    In this study we present a device based on surface-enhanced Raman scattering (SERS) for the detection of airborne explosives. The explosives are resublimated on a cooled nanostructured gold substrate. The explosives trinitrotoluene (TNT) and triacetone triperoxide (TATP) are used. The SERS spectrum of the explosives is analyzed. Thus, TNT is deposited from an acetonitrile solution on the gold substrate. In the case of TATP, first the bulk TATP Raman spectrum was recorded and compared with the SERS spectrum, generated by deposition out of the gas phase. The frequencies of the SERS spectrum are hardly shifted compared to the spectrum of bulk TATP. The influence of the nanostructured gold substrate temperature on the signals of TATP was studied. A decrease in temperature up to 200 K increased the intensities of the TATP bands in the SERS spectrum; below 200 K, the TATP fingerprint disappeared. PMID:20697437

  13. Polyacrylamide based ICG nanocarriers for enhanced fluorescence and photoacoustic imaging

    NASA Astrophysics Data System (ADS)

    Ray, Aniruddha; Yoon, Hyung Ki; Ryu, HeeJu; Koo Lee, Yong-Eun; Kim, Gwangseong; Wang, Xueding; Kopelman, Raoul

    2013-02-01

    Indocyanine green (ICG) is an FDA approved tricarbocyanine dye. This dye, with a strong absorbance in the near infrared (NIR) region, has been extensively used for fluorescence and photoacoustic imaging in vivo. ICG in its free form, however, has a few drawbacks that limit its in vivo applications, such as non-targetability, tendency to form aggregates which changes its optical properties, fast degradation, short plasma lifetime and reduced fluorescence at body temperature. In order to bypass these inherent drawbacks, we demonstrate a polyacrylamide based nanocarrier that was particularly designed to carry the negatively charged ICG molecules. These nanocarriers are biodegradable, biocompatible and can be specifically targeted to any cell or tissue. Using these nanocarriers we avoid all the problems associated with free ICG, such as degradation, aggregation and short plasma lifetime, and also enhance demonstrate its ability towards photoacoustics and fluorescence imaging.

  14. Enhanced Corrosion Resistance of Iron-Based Amorphous Alloys

    SciTech Connect

    Rebak, R B; Day, S D; Lian, T; Aprigliano, L F; Hailey, P D; Farmer, J C

    2007-02-18

    Iron-based amorphous alloys possess enhanced hardness and are highly resistant to corrosion, which make them desirable for wear applications in corrosive environments. It was of interest to examine the behavior of amorphous alloys during anodic polarization in concentrated salt solutions and in the salt-fog testing. Results from the testing of one amorphous material (SAM2X5) both in ribbon form and as an applied coating are reported here. Cyclic polarization tests were performed on SAM2X5 ribbon as well as on other nuclear engineering materials. SAM2X5 showed the highest resistance to localized corrosion in 5 M CaCl{sub 2} solution at 105 C. Salt fog tests of 316L SS and Alloy 22 coupons coated with amorphous SAM2X5 powder showed resistance to rusting. Partial devitrification may be responsible for isolated pinpoint rust spots in some coatings.

  15. Enhancing exposure-based therapy from a translational research perspective.

    PubMed

    Hofmann, Stefan G

    2007-09-01

    Combining an effective psychological treatment with conventional anxiolytic medication is typically not more effective than unimodal therapy for treating anxiety disorders. However, recent advances in the neuroscience of fear reduction have led to novel approaches for combining psychological therapy and pharmacological agents. Exposure-based treatments in humans partly rely on extinction to reduce the fear response in anxiety disorders. Animal studies have shown that D-cycloserine (DCS), a partial agonist at the glycine recognition site of the glutamatergic N-methyl-D-aspartate receptor facilitates extinction learning. Similarly, recent human trials have shown that DCS enhances fear reduction during exposure therapy of some anxiety disorders. This article discusses the biological and psychological mechanisms of extinction learning and the therapeutic value of DCS as an augmentation strategy for exposure therapy. Areas of future research will be identified.

  16. Detection of explosives based on surface-enhanced Raman spectroscopy.

    PubMed

    Wackerbarth, Hainer; Salb, Christian; Gundrum, Lars; Niederkrüger, Matthias; Christou, Konstantin; Beushausen, Volker; Viöl, Wolfgang

    2010-08-10

    In this study we present a device based on surface-enhanced Raman scattering (SERS) for the detection of airborne explosives. The explosives are resublimated on a cooled nanostructured gold substrate. The explosives trinitrotoluene (TNT) and triacetone triperoxide (TATP) are used. The SERS spectrum of the explosives is analyzed. Thus, TNT is deposited from an acetonitrile solution on the gold substrate. In the case of TATP, first the bulk TATP Raman spectrum was recorded and compared with the SERS spectrum, generated by deposition out of the gas phase. The frequencies of the SERS spectrum are hardly shifted compared to the spectrum of bulk TATP. The influence of the nanostructured gold substrate temperature on the signals of TATP was studied. A decrease in temperature up to 200 K increased the intensities of the TATP bands in the SERS spectrum; below 200 K, the TATP fingerprint disappeared.

  17. Enhancement of hydrogen production in a single chamber microbial electrolysis cell through anode arrangement optimization.

    PubMed

    Liang, Da-Wei; Peng, Si-Kan; Lu, Shan-Fu; Liu, Yan-Yan; Lan, Fei; Xiang, Yan

    2011-12-01

    Reducing the inner resistances is crucial for the enhancement of hydrogen generation in microbial electrolysis cells (MECs). This study demonstrates that the optimization of the anode arrangement is an effective strategy to reduce the system resistances. By changing the normal MEC configuration into a stacking mode, namely separately placing the contacted anodes from one side to both sides of cathode in parallel, the solution, biofilm and polarization resistances of MECs were greatly reduced, which was also confirmed with electrochemical impedance spectroscopy analysis. After the anode arrangement optimization, the current and hydrogen production rate (HPR) of MEC could be enhanced by 72% and 118%, reaching 621.3±20.6 A/m3 and 5.56 m3/m3 d respectively, under 0.8 V applied voltage. A maximum current density of 1355 A/m3 with a HPR of 10.88 m3/m3 d can be achieved with 1.5 V applied voltage.

  18. Recognition of novel faces after single exposure is enhanced during pregnancy.

    PubMed

    Anderson, Marla V; Rutherford, M D

    2011-01-01

    Protective mechanisms in pregnancy include Nausea and Vomiting in Pregnancy (NVP) (Fessler, 2002; Flaxman and Sherman, 2000), increased sensitivity to health cues (Jones et al., 2005), and increased vigilance to out-group members (Navarette, Fessler, and Eng, 2007). While common perception suggests that pregnancy results in decreased cognitive function, an adaptationist perspective might predict that some aspects of cognition would be enhanced during pregnancy if they help to protect the reproductive investment. We propose that a reallocation of cognitive resources from nonessential to critical areas engenders the cognitive decline observed in some studies. Here, we used a recognition task disguised as a health rating to determine whether pregnancy facilitates face recognition. We found that pregnant women were significantly better at recognizing faces and that this effect was particularly pronounced for own-race male faces. In human evolutionary history, and today, males present a significant threat to females. Thus, enhanced recognition of faces, and especially male faces, during pregnancy may serve a protective function.

  19. Structural examination of iridium-based single-crystal preparations

    NASA Astrophysics Data System (ADS)

    Axler, K. M.; Roof, R. B.

    A high-temperature crystal growth experiment produced discrete single-crystal products of AlIr and IrSi. The preparation and examination of these phases is described within. This project is part of a materials compatibility study relating to radioisotopic heat sources. These heat sources are comprised of a PuO2 fuel pellet encapsulated in an Ir alloy containment shell. Th is introduced as an additive within the Ir to maintain ductility. Si and P are picked up inadvertently in the fuel processing. The compatibility of the heat sources with Al is of interest because of potential interactions with Al alloy hardware associated with the heat source environment.

  20. Photon-activated electron hopping in a single-electron trap enhanced by Josephson radiation

    NASA Astrophysics Data System (ADS)

    Lotkhov, S. V.; Jalali-Jafari, B.; Zorin, A. B.

    2016-04-01

    Using a Josephson junction interferometer (DC SQUID) as a microwave source for irradiating a single-electron trap, both devices fabricated on the same chip, we study the process of photon-assisted tunneling as an effective mechanism of single photon detection. High sensitivity down to a very small oscillation amplitude v J ˜ 10 nV ≪ E act ≲ h f J and down to low photon absorption rates Γph ˜ (1-50) Hz, as well as a clear threshold type of operation with an activation energy Eact ˜ 400 μeV, is demonstrated for the trap with respect to the microwave photons of frequency fJ ˜ (100-200) GHz. Tunable generation is demonstrated with respect to the power and frequency of the microwave signal produced by the SQUID source biased within the subgap voltage range. A much weaker effect is observed at the higher junction voltages along the quasiparticle branch of the I-V curve; this response mostly appears due to the recombination phonons.

  1. Weak Ligand-Field Effect from Ancillary Ligands on Enhancing Single-Ion Magnet Performance.

    PubMed

    Meng, Yin-Shan; Zhang, Yi-Quan; Wang, Zhe-Ming; Wang, Bing-Wu; Gao, Song

    2016-08-26

    A series of bis-pentamethylcyclopentadienyl-supported Dy complexes containing different ancillary ligands were synthesized and characterized. Magnetic studies showed that 1 Dy [Cp*2 DyCl(THF)], 1 Dy' [Cp*2 DyCl2 K(THF)]n , 2 Dy [Cp*2 DyBr(THF)], 3 Dy [Cp*2 DyI(THF)] and 4 Dy [Cp*2 DyTp] (Tp=hydrotris(1-pyrazolyl)borate) were single-ion magnets (SIMs). The 1D dysprosium chain 1 Dy' exhibited a hysteresis at up to 5 K. Furthermore, 3 Dy featured the highest energy barrier (419 cm(-1) ) among the complexes. The effects of ancillary ligands on single-ion magnetic properties were studied by experimental, ab initio calculations and electrostatic analysis methods in detail. These results demonstrated that the QTM rate was strongly dependent on the ancillary ligands and that a weak equatorial ligand field could be beneficial for constructing Dy-SIMs. PMID:27417884

  2. Single-walled carbon nanotube incorporated novel three phase carbon/epoxy composite with enhanced properties.

    PubMed

    Rana, Sohel; Alagirusamy, Ramasamy; Joshi, Mangala

    2011-08-01

    In the present work, single-walled carbon nanotubes were dispersed within the matrix of carbon fabric reinforced epoxy composites in order to develop novel three phase carbon/epoxy/single-walled carbon nanotube composites. A combination of ultrasonication and high speed mechanical stirring at 2000 rpm was used to uniformly disperse carbon nanotubes in the epoxy resin. The state of carbon nanotube dispersion in the epoxy resin and within the nanocomposites was characterized with the help of optical microscopy and atomic force microscopy. Pure carbon/epoxy and three phase composites were characterized for mechanical properties (tensile and compressive) as well as for thermal and electrical conductivity. Fracture surfaces of composites after tensile test were also studied in order to investigate the effect of dispersed carbon nanotubes on the failure behavior of composites. Dispersion of only 0.1 wt% nanotubes in the matrix led to improvements of 95% in Young's modulus, 31% in tensile strength, 76% in compressive modulus and 41% in compressive strength of carbon/epoxy composites. In addition to that, electrical and thermal conductivity also improved significantly with addition of carbon nanotubes.

  3. Spiro-OMeTAD single crystals: Remarkably enhanced charge-carrier transport via mesoscale ordering

    PubMed Central

    Shi, Dong; Qin, Xiang; Li, Yuan; He, Yao; Zhong, Cheng; Pan, Jun; Dong, Huanli; Xu, Wei; Li, Tao; Hu, Wenping; Brédas, Jean-Luc; Bakr, Osman M.

    2016-01-01

    We report the crystal structure and hole-transport mechanism in spiro-OMeTAD [2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenyl-amine)9,9′-spirobifluorene], the dominant hole-transporting material in perovskite and solid-state dye-sensitized solar cells. Despite spiro-OMeTAD’s paramount role in such devices, its crystal structure was unknown because of highly disordered solution-processed films; the hole-transport pathways remained ill-defined and the charge carrier mobilities were low, posing a major bottleneck for advancing cell efficiencies. We devised an antisolvent crystallization strategy to grow single crystals of spiro-OMeTAD, which allowed us to experimentally elucidate its molecular packing and transport properties. Electronic structure calculations enabled us to map spiro-OMeTAD’s intermolecular charge-hopping pathways. Promisingly, single-crystal mobilities were found to exceed their thin-film counterparts by three orders of magnitude. Our findings underscore mesoscale ordering as a key strategy to achieving breakthroughs in hole-transport material engineering of solar cells. PMID:27152342

  4. Single-pulse enhanced coherent diffraction imaging of bacteria with an X-ray free-electron laser

    PubMed Central

    Fan, Jiadong; Sun, Zhibin; Wang, Yaling; Park, Jaehyun; Kim, Sunam; Gallagher-Jones, Marcus; Kim, Yoonhee; Song, Changyong; Yao, Shengkun; Zhang, Jian; Zhang, Jianhua; Duan, Xiulan; Tono, Kensuke; Yabashi, Makina; Ishikawa, Tetsuya; Fan, Chunhai; Zhao, Yuliang; Chai, Zhifang; Gao, Xueyun; Earnest, Thomas; Jiang, Huaidong

    2016-01-01

    High-resolution imaging offers one of the most promising approaches for exploring and understanding the structure and function of biomaterials and biological systems. X-ray free-electron lasers (XFELs) combined with coherent diffraction imaging can theoretically provide high-resolution spatial information regarding biological materials using a single XFEL pulse. Currently, the application of this method suffers from the low scattering cross-section of biomaterials and X-ray damage to the sample. However, XFELs can provide pulses of such short duration that the data can be collected using the “diffract and destroy” approach before the effects of radiation damage on the data become significant. These experiments combine the use of enhanced coherent diffraction imaging with single-shot XFEL radiation to investigate the cellular architecture of Staphylococcus aureus with and without labeling by gold (Au) nanoclusters. The resolution of the images reconstructed from these diffraction patterns were twice as high or more for gold-labeled samples, demonstrating that this enhancement method provides a promising approach for the high-resolution imaging of biomaterials and biological systems. PMID:27659203

  5. Single-pulse enhanced coherent diffraction imaging of bacteria with an X-ray free-electron laser

    NASA Astrophysics Data System (ADS)

    Fan, Jiadong; Sun, Zhibin; Wang, Yaling; Park, Jaehyun; Kim, Sunam; Gallagher-Jones, Marcus; Kim, Yoonhee; Song, Changyong; Yao, Shengkun; Zhang, Jian; Zhang, Jianhua; Duan, Xiulan; Tono, Kensuke; Yabashi, Makina; Ishikawa, Tetsuya; Fan, Chunhai; Zhao, Yuliang; Chai, Zhifang; Gao, Xueyun; Earnest, Thomas; Jiang, Huaidong

    2016-09-01

    High-resolution imaging offers one of the most promising approaches for exploring and understanding the structure and function of biomaterials and biological systems. X-ray free-electron lasers (XFELs) combined with coherent diffraction imaging can theoretically provide high-resolution spatial information regarding biological materials using a single XFEL pulse. Currently, the application of this method suffers from the low scattering cross-section of biomaterials and X-ray damage to the sample. However, XFELs can provide pulses of such short duration that the data can be collected using the “diffract and destroy” approach before the effects of radiation damage on the data become significant. These experiments combine the use of enhanced coherent diffraction imaging with single-shot XFEL radiation to investigate the cellular architecture of Staphylococcus aureus with and without labeling by gold (Au) nanoclusters. The resolution of the images reconstructed from these diffraction patterns were twice as high or more for gold-labeled samples, demonstrating that this enhancement method provides a promising approach for the high-resolution imaging of biomaterials and biological systems.

  6. The effects of a single session of upper alpha neurofeedback for cognitive enhancement: a sham-controlled study.

    PubMed

    Escolano, C; Navarro-Gil, M; Garcia-Campayo, J; Minguez, J

    2014-12-01

    The minimization of the non-specific factors of neurofeedback (NF) is an important aspect to further advance in the understanding of the effects of these types of procedures. This paper investigates the NF effects of a single session (25 min) of individual upper alpha enhancement following a sham-controlled experimental design (19 healthy participants). We measured immediate effects after the training and 1-day lasting EEG effects (eyes closed resting state and task-related activity), as well as the event-locked EEG effects during the execution of a mental rotation task. These metrics were computed in trained (upper alpha) and non-trained EEG parameters (lower alpha and lower beta). Several cognitive functions were assessed such as working memory and mental rotation abilities. The NF group showed increased upper alpha power after training in task-related activity (not significantly sustained 1 day after) and higher pre-stimulus power during the mental rotation task. Both groups improved cognitive performance, with a more prominent improvement for the NF group, however a single session seems to be insufficient to yield significant differences between groups. A higher number of training sessions seems necessary to achieve long-lasting effects on the electrophysiology and to enhance the behavioral effects.

  7. PSO Based Optimal Power Flow with FACTS Devices for Security Enhancement Considering Credible Network Contingencies

    NASA Astrophysics Data System (ADS)

    Rambabu, C.; Obulesu, Y. P.; Saibabu, Ch.

    2014-07-01

    This work presents particle swarm optimization (PSO) based method to solve the optimal power flow in power systems incorporating flexible AC transmission systems controllers such as thyristor controlled phase shifter, thyristor controlled series compensator and unified power flow controller for security enhancement under single network contingencies. A fuzzy contingency ranking method is used in this paper and observed that it effectively eliminates the masking effect when compared with other methods of contingency ranking. The fuzzy based network composite overall severity index is used as an objective to be minimized to improve the security of the power system. The proposed optimization process with PSO is presented with case study example using IEEE 30-bus test system to demonstrate its applicability. The results are presented to show the feasibility and potential of this new approach.

  8. Enhanced Surface Superconductivity in Single Crystal La2-xBaxCuO4

    NASA Astrophysics Data System (ADS)

    Martin, Ivar; Tee, Xian Yang; Ito, Toshimitsu; Ushiyama, Tomoharu; Tomioka, Yasuhide; Panagopoulos, Christos

    Surfaces of materials often possess properties which are distinctly different from their bulk. The atomic structure can develop intricate new patterns due to surface reconstruction and the electronic properties can be very distinct, as most dramatically manifested in topological insulators. However, more subtle collective phenomena such as superconductivity are not as strongly affected by the presence of surfaces. Here, we report an unprecedented finding of enhanced superconductivity at the ab-plane surface of high-Tc cuprate La2-xBaxCuO4. Spatially-resolved electrical and thermoelectric transport measurements detect a superconducting surface below the transition temperature Tcs which is considerably higher than the bulk Tc. The effect is pronounced in the region of charge carrier doping (x) with strong spin-charge stripe correlations. Notably, for x = 0 . 12 , Tcs reaches 36 K, exceeding even the highest reported bulk Tc in this material for any doping. Possible interpretations for the novel effect are discussed.

  9. Enhanced Hydrogen Production Integrated with CO2 Separation in a Single-Stage

    SciTech Connect

    Mahesh Iyer; Shwetha Ramkumar; Liang-Shih Fan

    2006-09-30

    Enhancement in the production of high purity hydrogen from fuel gas, obtained from coal gasification, is limited by thermodynamics of the Water Gas Shift Reaction. However, this constraint can be overcome by concurrent water-gas shift (WGS) and carbonation reactions to enhance H{sub 2} production by incessantly driving the equilibrium-limited WGS reaction forward and in-situ removing the CO2 product from the gas mixture. The spent sorbent is then regenerated by calcining it to produce a pure stream of CO{sub 2} and CaO which can be reused. However while performing the cyclic carbonation and calcination it was observed that the CO{sub 2} released during the in-situ calcination causes the deactivation of the iron oxide WGS catalyst. Detailed understanding of the iron oxide phase diagram helped in developing a catalyst pretreatment procedure using a H{sub 2}/H{sub 2}O system to convert the deactivated catalyst back to its active magnetite (Fe{sub 3}O{sub 4}) form. The water gas shift reaction was studied at different temperatures, different steam to carbon monoxide ratios (S/C) 3:1, 2:1, 1:1 and different total pressures ranging from 0-300 psig. The combined water gas shift and carbonation reaction was investigated at temperatures ranging from 600-700C, S/C ratio of 3:1 to 1:1 and at different pressures of 0-300 psig and the calcium looping process was found to produce high purity hydrogen with in-situ CO{sub 2} capture.

  10. Enhanced Hydrogen Production Integrated with CO2 Separation in a Single-Stage Reactor

    SciTech Connect

    Mahesh Iyer; Shwetha Ramkumar; Liang-Shih Fan

    2006-03-31

    Hydrogen production from coal gasification can be enhanced by driving the equilibrium limited Water Gas Shift reaction forward by incessantly removing the CO{sub 2} by-product via the carbonation of calcium oxide. This project uses the high-reactivity mesoporous precipitated calcium carbonate sorbent for removing the CO{sub 2} product to enhance H{sub 2} production. Preliminary experiments demonstrate the show the superior performance of the PCC sorbent over other naturally occurring calcium sorbents. It was observed that the CO{sub 2} released during the in-situ calcination causes the deactivation of the iron oxide WGS catalyst by changing the active phase of the catalyst from magnetite (F{sub 3}O{sub 4}). Detailed understanding of the iron oxide phase diagram helped in developing a catalyst pretreatment procedure using a H{sub 2}/H{sub 2}O system. Intermediate catalyst pretreatment helps prevent its deactivation by reducing the catalyst back to its active magnetite (Fe{sub 3}O{sub 4}) form. Multicyclic runs which consist of combined WGS/carbonation reaction followed by in-situ calcination with a subsequent catalyst pretreatment procedure sustains the catalytic activity and prevents deactivation. The water gas shift reaction was studied at different temperatures, different steam to carbon monoxide ratios (S/C) 3:1, 2:1, 1:1 and different total pressures ranging from 0-300 psig. The CO conversion was found to have an optimal value with increasing pressure, S/C ratio and temperatures. The combined water gas shift and carbonation reaction was investigated at 650 C, S/C ratio of 3:1and at different pressures of 0-300 psig.

  11. Enhanced Recovery after Surgery in a Single High-Volume Surgical Oncology Unit: Details Matter

    PubMed Central

    Vohra, Nasreen A.; Edwards, Kimberly V.; Zervos, Emmanuel E.

    2016-01-01

    Benefits of ERAS protocol have been well documented; however, it is unclear whether the improvement stems from the protocol or shifts in expectations. Interdisciplinary educational seminars were conducted for all health professionals. However, one test surgeon adopted the protocol. 394 patients undergoing elective abdominal surgery from June 2013 to April 2015 with a median age of 63 years were included. The implementation of ERAS protocol resulted in a decrease in the length of stay (LOS) and mortality, whereas the difference in cost was found to be insignificant. For the test surgeon, ERAS was associated with decreased LOS, cost, and mortality. For the control providers, the LOS, cost, mortality, readmission rates, and complications remained similar both before and after the implementation of ERAS. An ERAS protocol on the single high-volume surgical unit decreased the cost, LOS, and mortality. PMID:27648469

  12. Enhanced Recovery after Surgery in a Single High-Volume Surgical Oncology Unit: Details Matter.

    PubMed

    Fitzgerald, Timothy L; Mosquera, Catalina; Koutlas, Nicholas J; Vohra, Nasreen A; Edwards, Kimberly V; Zervos, Emmanuel E

    2016-01-01

    Benefits of ERAS protocol have been well documented; however, it is unclear whether the improvement stems from the protocol or shifts in expectations. Interdisciplinary educational seminars were conducted for all health professionals. However, one test surgeon adopted the protocol. 394 patients undergoing elective abdominal surgery from June 2013 to April 2015 with a median age of 63 years were included. The implementation of ERAS protocol resulted in a decrease in the length of stay (LOS) and mortality, whereas the difference in cost was found to be insignificant. For the test surgeon, ERAS was associated with decreased LOS, cost, and mortality. For the control providers, the LOS, cost, mortality, readmission rates, and complications remained similar both before and after the implementation of ERAS. An ERAS protocol on the single high-volume surgical unit decreased the cost, LOS, and mortality. PMID:27648469

  13. Enhanced Recovery after Surgery in a Single High-Volume Surgical Oncology Unit: Details Matter

    PubMed Central

    Vohra, Nasreen A.; Edwards, Kimberly V.; Zervos, Emmanuel E.

    2016-01-01

    Benefits of ERAS protocol have been well documented; however, it is unclear whether the improvement stems from the protocol or shifts in expectations. Interdisciplinary educational seminars were conducted for all health professionals. However, one test surgeon adopted the protocol. 394 patients undergoing elective abdominal surgery from June 2013 to April 2015 with a median age of 63 years were included. The implementation of ERAS protocol resulted in a decrease in the length of stay (LOS) and mortality, whereas the difference in cost was found to be insignificant. For the test surgeon, ERAS was associated with decreased LOS, cost, and mortality. For the control providers, the LOS, cost, mortality, readmission rates, and complications remained similar both before and after the implementation of ERAS. An ERAS protocol on the single high-volume surgical unit decreased the cost, LOS, and mortality.

  14. Toward chaperone-assisted crystallography: Protein engineering enhancement of crystal packing and X-ray phasing capabilities of a camelid single-domain antibody (VHH) scaffold

    PubMed Central

    Tereshko, Valentina; Uysal, Serdar; Koide, Akiko; Margalef, Katrina; Koide, Shohei; Kossiakoff, Anthony A.

    2008-01-01

    A crystallization chaperone is an auxiliary protein that binds to a target of interest, enhances and modulates crystal packing, and provides high-quality phasing information. We critically evaluated the effectiveness of a camelid single-domain antibody (VHH) as a crystallization chaperone. By using a yeast surface display system for VHH, we successfully introduced additional Met residues in the core of the VHH scaffold. We identified a set of SeMet-labeled VHH variants that collectively produced six new crystal forms as the complex with the model antigen, RNase A. The crystals exhibited monoclinic, orthorhombic, triclinic, and tetragonal symmetry and have one or two complexes in the asymmetric unit, some of which diffracted to an atomic resolution. The phasing power of the Met-enriched VHH chaperone allowed for auto-building the entire complex using single-anomalous dispersion technique (SAD) without the need for introducing SeMet into the target protein. We show that phases produced by combining SAD and VHH model-based phases are accurate enough to easily solve structures of the size reported here, eliminating the need to collect multiple wavelength multiple-anomalous dispersion (MAD) data. Together with the presence of high-throughput selection systems (e.g., phage display libraries) for VHH, the enhanced VHH domain described here will be an excellent scaffold for producing effective crystallization chaperones. PMID:18445622

  15. Single-Dose Electrospun Nanoparticles-in-Nanofibers Wound Dressings with Enhanced Epithelialization, Collagen Deposition, and Granulation Properties.

    PubMed

    Ali, Isra H; Khalil, Islam A; El-Sherbiny, Ibrahim M

    2016-06-15

    Phenytoin (Ph), an antiepileptic drug, was reported to exhibit high wound healing activity. However, its limited solubility, bioavailability, and inefficient distribution during topical administration limit its use. Therefore, this study aims to develop new single-dose electrospun nanoparticles-in-nanofibers (NPs-in-NFs) wound dressings that allow a well-controlled release of Ph. These NPs-in-NFs systems are based on enhanced chitosan (CS)/poly(ethylene oxide) (PEO) electrospun nanofibers (NFs) incorporating optimized Ph-loaded nanocarriers. First, a study was conducted to investigate Ph loading efficiency into polymeric nanocarriers of different types; pluronic nanomicelles and poly(lactic-co-glycolic) acids nanoparticles (PLGA NPs). The drug release profile from the nanocarriers was further optimized via lecithin coating. Second, different electrospinning parameters were manipulated to fabricate beads-free homogeneous NFs with optimized polymer ratios. Plain and Ph-loaded nanocarriers were characterized using Fourier transform infrared (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), dynamic light scattering (DLS), and scanning electron microscopy (SEM). Both entrapment efficiency of Ph (EE%) and its release profile in phosphate buffer saline (PBS; pH 5.5), simulating the wound environment, were studied. Biodegradability, swelling, vapor permeability, and porosity of the developed Ph-loaded NPs-in-NFs wound dressings were investigated. Morphology of the NPs-in-NFs was also studied using SEM and confocal laser microscopy (CLSM). Besides, the release profiles of Ph from the optimized NPs-in-NFs were assessed. The newly developed wound dressings were evaluated in vitro for their cytotoxicity using human fibroblasts and in vivo using a wound healing mice model. Nanocarriers with particle size ranging from 100 to 180 nm were successfully prepared. All nanocarriers attained a high drug entrapment efficiency exceeding 94% and showed

  16. Enhanced visible light photocatalytic performance of polyaniline modified mesoporous single crystal TiO2 microsphere

    NASA Astrophysics Data System (ADS)

    Deng, Yaocheng; Tang, Lin; Zeng, Guangming; Dong, Haoran; Yan, Ming; Wang, Jingjing; Hu, Wei; Wang, Jiajia; Zhou, Yaoyu; Tang, Jing

    2016-11-01

    Polyaniline (PANI) modified mesoporous single crystal TiO2 microsphere (PANI/MS-TiO2) with excellent photocatalytic activity was successfully prepared by a simple method of solution evaporation and chemisorption. The X-ray diffraction characterization demonstrated that the whole MS-TiO2 kept the crystal type of anatase. The nitrogen adsorption-desorption characterization coupled with scanning electron microscopy indicated that the MS-TiO2 possessed a unique mesoporous structure with high specific surface area, which resulted in the increased load of PANI on the surface of MS-TiO2 and multiple light reflection in the photocatalyst. The UV-vis diffuse reflectance spectra confirmed that PANI/MS-TiO2 presented more absorption ability in the visible light range than that of the pristine MS-TiO2. The transient photocurrent responses and electrochemical impedance spectroscopy (EIS) indicated the high photo responses and fast photogenerated charge separation efficiency of PANI/MS-TiO2. The photocatalytic activity of the PANI/MS-TiO2 was evaluated by the photodegradation of RhB and MB under visible light irradiation. MS-TiO2 photocatalyst with different molar ration of PANI had been prepared, and the results showed that the optimal photocatalyst (PANI/MS-TiO2 (1:40)) exhibited the highest photocatalytic efficiency which is nearly three times as great as that of pristine MS-TiO2 for the degradation of the RhB and MB under visible light irradiation. The remarkable performance of the PANI/MS-TiO2 under visible light was attributed to its mesoporous single crystal structure with large surface, conductivity, as well as the synergistic effect between PANI and MS-TiO2.

  17. Enhancing data exploitation through DTN-based data transmission protocols

    NASA Astrophysics Data System (ADS)

    Daglis, Ioannis A.; Tsaoussidis, Vassilis; Rontogiannis, Athanasios; Balasis, Georgios; Keramitsoglou, Iphigenia; Paronis, Dimitrios; Sykioti, Olga; Tsinganos, Antonios

    2014-05-01

    Data distribution and data access are major issues in space sciences and geosciences as they strongly influence the degree of data exploitation. Processing and analysis of large volumes of Earth observation and space/planetary data face two major impediments: limited access capabilities due to narrow connectivity windows between spacecraft and ground receiving stations and lack of sufficient communication and dissemination mechanisms between space data receiving centres and the end-user community. Real-time data assimilation that would be critical in a number of forecasting capabilities is particularly affected by such limitations. The FP7-Space project "Space-Data Routers" (SDR) has the aim of allowing space agencies, academic institutes and research centres to disseminate/share space data generated by single or multiple missions, in an efficient, secure and automated manner. The approach of SDR relies on space internetworking - and in particular on Delay-Tolerant Networking (DTN), which marks the new era in space communications, unifies space and earth communication infrastructures and delivers a set of tools and protocols for space-data exploitation. The project includes the definition of limitations imposed by typical space mission scenarios in which the National Observatory of Athens is currently involved, including space and planetary exploration, as well as satellite-supported geoscience applications. In this paper, we present the mission scenarios, the SDR-application and the evaluation of the associated impact from the space-data router enhancements. The work leading to this paper has received funding from the European Union's Seventh Framework Programme (FP7-SPACE-2010-1) under grant agreement no. 263330 for the SDR (Space-Data Routers for Exploiting Space Data) collaborative research project. This paper reflects only the authors' views and the Union is not liable for any use that may be made of the information contained therein.

  18. Single particle demultiplexer based on domain wall conduits

    NASA Astrophysics Data System (ADS)

    Torti, A.; Mondiali, V.; Cattoni, A.; Donolato, M.; Albisetti, E.; Haghiri-Gosnet, A. M.; Vavassori, Paolo; Bertacco, R.

    2012-10-01

    The remote manipulation of micro and nano-sized magnetic particles carrying molecules or biological entities over a chip surface is of paramount importance for future on-chip applications in biology and medicine. In this paper, we present a method for the on-chip demultiplexing of individual magnetic particles using bifurcated magnetic nano-conduits for the propagation of constrained domain walls (DWs). We demonstrate that the controlled injection and propagation of a domain wall in a bifurcation allow capturing, transporting, and sorting a single magnetic particle between two predefined paths. The cascade of n levels of such building blocks allows for the implementation of a variety of complex sorting devices as, e.g., a demultiplexer for the controlled sorting among 2n paths.

  19. Group velocity enhancement for guided lightwave by band-pulling effect in single-mode silicon comb photonic crystal wires

    NASA Astrophysics Data System (ADS)

    Thubthimthong, Borriboon; Hane, Kazuhiro

    2015-05-01

    Photonic crystal waveguides (PCWs), which usually exhibit the slow-light effect near the band edge frequency, may in fact be used to induce higher group velocity (vg). The presence of the band edge, due to periodically carving a strip waveguide (SW) into a PCW of a comb-shape dielectric wire, results in the band-pulling effect. The band-pulling effect, which lifts the fundamental photonic band toward the band gap, not only enhances vg by reducing the effective index but also prevents the band from bending toward the light cone of the core material, leading to additional vg enhancement. The maximum PCW vg (0.43c; c = vacuum light speed) found from numerical modeling was higher than SW vg at all widths and thicknesses, except for extremely low thickness below 80 nm. We found by numerical modeling and experiments that up to 75% enhancement at the 1550 nm wavelength may be achieved in a fabricated single-mode PCW (0.38c) compared with an SW (0.21c) of the same width and thickness. The higher vg was confirmed by measuring the PCW’s group index using ring resonators. The PCW propagation loss of 2.1 dB mm-1 and the bandwidth-distance product of 100 Gb/s-cm were deduced from experimental results. Our findings seemed encouraging for employing PCWs in optical interconnect applications.

  20. DNA-histone interactions are sufficient to position a single nucleosome juxtaposing Drosophila Adh adult enhancer and distal promoter.

    PubMed Central

    Jackson, J R; Benyajati, C

    1993-01-01

    The alcohol dehydrogenase gene (Adh) of Drosophila melanogaster is transcribed from two tandem promoters in distinct developmental and tissue-specific patterns. Both promoters are regulated by separate upstream enhancer regions. In its wild-type context the adult enhancer specifically stimulates only the distal promoter, approximately 400 bp downstream, and not the proximal promoter, which is approximately 700 bp further downstream. Genomic footprinting and micrococcal nuclease analyses have revealed a specifically positioned nucleosome between the distal promoter and adult enhancer. In vitro reconstitution of this nucleosome demonstrated that DNA-core histone interactions alone are sufficient to position the nucleosome. Based on this observation and sequence periodicities in the underlying DNA, the mechanism of positioning appears to involve specific DNA structural features (ie flexibility or curvature). We have observed this nucleosome positioned early during development, before tissue differentiation, and before non-histone protein-DNA interactions are established at the distal promoter or adult enhancer. This nucleosome positioning element in the Adh regulatory region could be involved in establishing a specific tertiary nucleoprotein structure that facilitates specific cis-element accessibility and/or distal promoter-adult enhancer interactions. Images PMID:8451195

  1. Vitamin B12 enhances the phase-response of circadian melatonin rhythm to a single bright light exposure in humans.

    PubMed

    Hashimoto, S; Kohsaka, M; Morita, N; Fukuda, N; Honma, S; Honma, K

    1996-12-13

    Eight young males were subjected to a single blind cross-over test to see the effects of vitamin B12 (methylcobalamin; VB12) on the phase-response of the circadian melatonin rhythm to a single bright light exposure. VB12 (0.5 mg/day) or vehicle was injected intravenously at 1230 h for 11 days, which was followed by oral administration (2 mg x 3/day) for 7 days. A serial blood sampling was performed under dim light condition (less than 200 lx) and plasma melatonin rhythm was determined before and after a single bright light exposure (2500 lx for 3 h) at 0700 h. The melatonin rhythm before the light exposure showed a smaller amplitude in the VB12 trial than in the placebo. The light exposure phase-advanced the melatonin rhythm significantly in the VB12 trail, but not in the placebo. These findings indicate that VB12 enhances the light-induced phase-shift in the human circadian rhythm. PMID:8981490

  2. Structural and dynamic changes associated with beneficial engineered single-amino-acid deletion mutations in enhanced green fluorescent protein

    SciTech Connect

    Arpino, James A. J.; Rizkallah, Pierre J.; Jones, D. Dafydd

    2014-08-01

    The beneficial engineered single-amino-acid deletion variants EGFP{sup D190Δ} and EGFP{sup A227Δ} have been studied. Single-amino-acid deletions are a common part of the natural evolutionary landscape but are rarely sampled during protein engineering owing to limited and prejudiced molecular understanding of mutations that shorten the protein backbone. Single-amino-acid deletion variants of enhanced green fluorescent protein (EGFP) have been identified by directed evolution with the beneficial effect of imparting increased cellular fluorescence. Biophysical characterization revealed that increased functional protein production and not changes to the fluorescence parameters was the mechanism that was likely to be responsible. The structure EGFP{sup D190Δ} containing a deletion within a loop revealed propagated changes only after the deleted residue. The structure of EGFP{sup A227Δ} revealed that a ‘flipping’ mechanism was used to adjust for residue deletion at the end of a β-strand, with amino acids C-terminal to the deletion site repositioning to take the place of the deleted amino acid. In both variants new networks of short-range and long-range interactions are generated while maintaining the integrity of the hydrophobic core. Both deletion variants also displayed significant local and long-range changes in dynamics, as evident by changes in B factors compared with EGFP. Rather than being detrimental, deletion mutations can introduce beneficial structural effects through altering core protein properties, folding and dynamics, as well as function.

  3. Multiplexed Detection of Cytokines Based on Dual Bar-Code Strategy and Single-Molecule Counting.

    PubMed

    Li, Wei; Jiang, Wei; Dai, Shuang; Wang, Lei

    2016-02-01

    Cytokines play important roles in the immune system and have been regarded as biomarkers. While single cytokine is not specific and accurate enough to meet the strict diagnosis in practice, in this work, we constructed a multiplexed detection method for cytokines based on dual bar-code strategy and single-molecule counting. Taking interferon-γ (IFN-γ) and tumor necrosis factor-α (TNF-α) as model analytes, first, the magnetic nanobead was functionalized with the second antibody and primary bar-code strands, forming a magnetic nanoprobe. Then, through the specific reaction of the second antibody and the antigen that fixed by the primary antibody, sandwich-type immunocomplex was formed on the substrate. Next, the primary bar-code strands as amplification units triggered multibranched hybridization chain reaction (mHCR), producing nicked double-stranded polymers with multiple branched arms, which were served as secondary bar-code strands. Finally, the secondary bar-code strands hybridized with the multimolecule labeled fluorescence probes, generating enhanced fluorescence signals. The numbers of fluorescence dots were counted one by one for quantification with epi-fluorescence microscope. By integrating the primary and secondary bar-code-based amplification strategy and the multimolecule labeled fluorescence probes, this method displayed an excellent sensitivity with the detection limits were both 5 fM. Unlike the typical bar-code assay that the bar-code strands should be released and identified on a microarray, this method is more direct. Moreover, because of the selective immune reaction and the dual bar-code mechanism, the resulting method could detect the two targets simultaneously. Multiple analysis in human serum was also performed, suggesting that our strategy was reliable and had a great potential application in early clinical diagnosis. PMID:26721199

  4. Compact, fiber-based, fast-light enhanced optical gyroscope

    NASA Astrophysics Data System (ADS)

    Christensen, Caleb A.; Zavriyev, Anton; Bashkansky, Mark; Beal, A. Craig

    2013-05-01

    It has been proposed that fast-light optical phenomena can increase the sensitivity of a Ring Laser Gyroscope (RLG) of a given size by several orders of magnitude. MagiQ is developing a compact fully-fibered fast light RLG using Stimulated Brillouin Scattering (SBS) in commercial optical fiber. We will discuss our experimental results on SBS pumped lasing in commercial fibers and analyze their implications to the fast light generation. Based on these results, we envision a fast light enhanced Ring Laser Gyroscope (RLG) that will use only a few meters of fiber and require moderate pump power (only a few 100's of mW). We will present the design that is based on proven, commercially available technologies. By using photonic integrated circuits and telecom-grade fiber components, we created a design that is appropriate for mass production in the near term. We eliminated all free-space optical elements (such as atomic vapor cells), in order to enable a compact, high sensitivity RLG stable against environmental disturbances. Results of this effort will have benefits in existing applications of RLGs (such as inertial navigation units, gyrocompasses, and stabilization techniques), and will allow wider use of RLGs in spacecraft, unmanned aerial vehicles or sensors, where the current size and weight of optical gyros are prohibitive.

  5. Enhanced photocoagulation with catheter-based diffusing optical device

    NASA Astrophysics Data System (ADS)

    Kang, Hyun Wook; Kim, Jeehyun; Oh, Jungwhan

    2012-11-01

    A novel balloon catheter-based diffusing optical device was designed and evaluated to assist in treating excessive menstrual bleeding. A synthetic fused-silica fiber was micro-machined precisely to create scattering segments on a 25 mm long fiber tip for uniform light distribution. A visible wavelength (λ=532 nm) was used to specifically target the endometrium due to the high vascularity of the uterine wall. Optical simulation presented 30% wider distribution of photons along with approximately 40% higher irradiance induced by addition of a glass cap to the diffuser tip. Incorporation of the optical diffuser with a polyurethane balloon catheter considerably enhanced coagulation depth and area (i.e., 3.5 mm and 18.9 cm2 at 1 min irradiation) in tissue in vitro. The prototype device demonstrated the coagulation necrosis of 2.8±1.2 mm (n=18) and no thermal damage to myometrium in in vivo caprine models. A prototype 5 cm long balloon catheter-assisted optical diffuser was also evaluated with a cadaveric human uterus to confirm the coagulative response of the uterine tissue as well as to identify the further design improvement and clinical applicability. The proposed catheter-based diffusing optical device can be a feasible therapeutic tool to photocoagulate endometrial cell layers in an efficient and safe manner.

  6. Enhanced vibration based energy harvesting using embedded acoustic black holes

    NASA Astrophysics Data System (ADS)

    Zhao, L.; Semperlotti, F.; Conlon, S. C.

    2014-03-01

    In this paper, we investigate the use of dynamic structural tailoring via the concept of an Acoustic Black Hole (ABH) to enhance the performance of piezoelectric based energy harvesting from operational mechanical vibrations. The ABH is a variable thickness structural feature that can be embedded in the host structure allowing a smooth reduction of the phase velocity while minimizing the amplitude of reflected waves. The ABH thickness variation is typically designed according to power-law profiles. As a propagating wave enters the ABH, it is progressively slowed down while its wavelength is compressed. This effect results in structural areas with high energy density that can be exploited effectively for energy harvesting. The potential of ABH for energy harvesting is shown via a numerical study based on fully coupled finite element electromechanical models of an ABH tapered plate with surface mounted piezo-transducers. The performances of the novel design are evaluated by direct comparison with a non-tapered structure in terms of energy ratios and attenuation indices. Results show that the tailored structural design allows a drastic increase in the harvested energy both for steady state and transient excitation. Performance dependencies of key design parameters are also investigated.

  7. An Enhanced Differential Evolution Algorithm Based on Multiple Mutation Strategies

    PubMed Central

    Xiang, Wan-li; Meng, Xue-lei; An, Mei-qing; Li, Yin-zhen; Gao, Ming-xia

    2015-01-01

    Differential evolution algorithm is a simple yet efficient metaheuristic for global optimization over continuous spaces. However, there is a shortcoming of premature convergence in standard DE, especially in DE/best/1/bin. In order to take advantage of direction guidance information of the best individual of DE/best/1/bin and avoid getting into local trap, based on multiple mutation strategies, an enhanced differential evolution algorithm, named EDE, is proposed in this paper. In the EDE algorithm, an initialization technique, opposition-based learning initialization for improving the initial solution quality, and a new combined mutation strategy composed of DE/current/1/bin together with DE/pbest/bin/1 for the sake of accelerating standard DE and preventing DE from clustering around the global best individual, as well as a perturbation scheme for further avoiding premature convergence, are integrated. In addition, we also introduce two linear time-varying functions, which are used to decide which solution search equation is chosen at the phases of mutation and perturbation, respectively. Experimental results tested on twenty-five benchmark functions show that EDE is far better than the standard DE. In further comparisons, EDE is compared with other five state-of-the-art approaches and related results show that EDE is still superior to or at least equal to these methods on most of benchmark functions. PMID:26609304

  8. Single-cell multiple gene expression analysis based on single-molecule-detection microarray assay for multi-DNA determination.

    PubMed

    Li, Lu; Wang, Xianwei; Zhang, Xiaoli; Wang, Jinxing; Jin, Wenrui

    2015-01-01

    We report a novel ultra-sensitive and high-selective single-molecule-detection microarray assay (SMA) for multiple DNA determination. In the SMA, a capture DNA (DNAc) microarray consisting of 10 subarrays with 9 spots for each subarray is fabricated on a silanized glass coverslip as the substrate. On the subarrays, the spot-to-spot spacing is 500 μm and each spot has a diameter of ∼300 μm. The sequence of the DNAcs on the 9 spots of a subarray is different, to determine 8 types of target DNAs (DNAts). Thus, 8 types of DNAts are captured to their complementary DNAcs at 8 spots of a subarray, respectively, and then labeled with quantum dots (QDs) attached to 8 types of detection DNAs (DNAds) with different sequences. The ninth spot is used to detect the blank value. In order to determine the same 8 types of DNAts in 10 samples, the 10 DNAc-modified subarrays on the microarray are identical. Fluorescence single-molecule images of the QD-labeled DNAts on each spot of the subarray are acquired using a home-made single-molecule microarray reader. The amounts of the DNAts are quantified by counting the bright dots from the QDs. For a microarray, 8 types of DNAts in 10 samples can be quantified in parallel. The limit of detection of the SMA for DNA determination is as low as 1.3×10(-16) mol L(-1). The SMA for multi-DNA determination can also be applied in single-cell multiple gene expression analysis through quantification of complementary DNAs (cDNAs) corresponding to multiple messenger RNAs (mRNAs) in single cells. To do so, total RNA in single cells is extracted and reversely transcribed into their cDNAs. Three types of cDNAs corresponding to beta-2-microglobulin, glyceraldehyde-3-phosphate dehydrogenase and ribosomal protein, large, P2 mRNAs in single human breast cancer cells and 5 random synthetic DNAts are simultaneously quantified to examine the SMA and SMA-based single-cell multiple gene expression analysis. PMID:25479875

  9. Single-cell multiple gene expression analysis based on single-molecule-detection microarray assay for multi-DNA determination.

    PubMed

    Li, Lu; Wang, Xianwei; Zhang, Xiaoli; Wang, Jinxing; Jin, Wenrui

    2015-01-01

    We report a novel ultra-sensitive and high-selective single-molecule-detection microarray assay (SMA) for multiple DNA determination. In the SMA, a capture DNA (DNAc) microarray consisting of 10 subarrays with 9 spots for each subarray is fabricated on a silanized glass coverslip as the substrate. On the subarrays, the spot-to-spot spacing is 500 μm and each spot has a diameter of ∼300 μm. The sequence of the DNAcs on the 9 spots of a subarray is different, to determine 8 types of target DNAs (DNAts). Thus, 8 types of DNAts are captured to their complementary DNAcs at 8 spots of a subarray, respectively, and then labeled with quantum dots (QDs) attached to 8 types of detection DNAs (DNAds) with different sequences. The ninth spot is used to detect the blank value. In order to determine the same 8 types of DNAts in 10 samples, the 10 DNAc-modified subarrays on the microarray are identical. Fluorescence single-molecule images of the QD-labeled DNAts on each spot of the subarray are acquired using a home-made single-molecule microarray reader. The amounts of the DNAts are quantified by counting the bright dots from the QDs. For a microarray, 8 types of DNAts in 10 samples can be quantified in parallel. The limit of detection of the SMA for DNA determination is as low as 1.3×10(-16) mol L(-1). The SMA for multi-DNA determination can also be applied in single-cell multiple gene expression analysis through quantification of complementary DNAs (cDNAs) corresponding to multiple messenger RNAs (mRNAs) in single cells. To do so, total RNA in single cells is extracted and reversely transcribed into their cDNAs. Three types of cDNAs corresponding to beta-2-microglobulin, glyceraldehyde-3-phosphate dehydrogenase and ribosomal protein, large, P2 mRNAs in single human breast cancer cells and 5 random synthetic DNAts are simultaneously quantified to examine the SMA and SMA-based single-cell multiple gene expression analysis.

  10. Environmentally enhanced crack growth in nickle-based superalloys

    NASA Astrophysics Data System (ADS)

    Huang, Zhifan Frank

    This dissertation research was designed to develop a better understand the role of niobium and other strengthening elements in enhancing crack growth by oxygen in nickel-based superalloys at high temperatures. It included modeling of diffusion controlled crack growth coupled with oxidation ahead of the crack tip, and an examination of the relationship between crack growth under sustained and fatigue loading. Three gamma' strengthened powder metallurgy (P/M) alloys (having about 53 vol. pct of gamma' precipitates), with 0, 2.5 and 5 wt pct niobium and with the formation of gamma″ precipitates suppressed, were specially designed for this study. Crack growth and supporting microstructural studies were conducted on the alloys. They were complemented by a separate surface chemistry study of the alloys, key precipitates, fracture surfaces of interrupted crack growth specimens by x-ray photoelectron spectroscopy (XPS). The results showed that sustained load and fatigue crack growth are directly related. Crack growth rates were significantly enhanced by oxygen, increasing by about 104 and 103 over those in argon (at 973 K) in the Nb containing and Nb free alloys, respectively. Crack growth was thermally activated, with an average apparent activation energy of about 250 kJ/mol; the actual values depended upon K and the alloys. The observed K dependence suggested oxygen diffusion control of crack growth, and was confirmed by results from the proposed model. Microstructural analyses of grain boundaries demonstrated that the Nb-containing phases were oxidized. The presence of zone of an oxygen affected region (OAR), or embrittled zone, ahead of the growing crack was established mechanically, and confirmed by XPS analyses. The XPS analyses showed preferential oxidization of Nb along with Al and Ti (principally of Nb-rich carbides, Ni3Al and Ni3Ti), but not Ni within the OAR. The results taken in toto show that embrittlement resulted from the formation and rupture of a brittle

  11. Ultrasound harmonic enhanced imaging using eigenspace-based coherence factor.

    PubMed

    Guo, Wei; Wang, Yuanyuan; Yu, Jinhua

    2016-12-01

    Tissue harmonic imaging (THI) utilizes harmonic signals generating within the tissue as the result of nonlinear acoustic wave propagation. With inadequate transmitting acoustic energy, THI is incapable to detect the small objects since poor harmonic signals have been generated. In most cases, high transmission energy cannot be guaranteed because of the imaging safety issue or specific imaging modality such as the plane wave imaging (PWI). Discrimination of small point targets such as calcification, however, is particularly important in the ultrasound diagnosis. Few efforts have been made to pursue the THI with high resolution and good small target visibility at the same time. In this paper, we proposed a new eigenspace-based coherence factor (ESBCF) beamformer to solve this problem. A new kind of coherence factor (CF), named as ESBCF, is firstly proposed to detect the point targets. The detected region-of-interest (ROI) is then enhanced adaptively by using a newly developed beamforming method. The ESBCF combines the information from signal eigenspace and coherence factor by expanding the CF to the covariance matrix of signal. Analogous to the image processing but in the radio frequency (RF) data domain, the proposed method fully utilizes the information from the fundamental and harmonic components. The performance of the proposed method is demonstrated by simulation and phantom experiments. The improvement of the point contrast ratio (PCR) is 7.6dB in the simulated data, and 6.0dB in the phantom experiment. Thanks to the improved small point detection ability of the ESBCF, the proposed beamforming algorithm can enhance the PCR considerably and maintain the high resolution of the THI at the same time. PMID:27513207

  12. Single passage in mouse organs enhances the survival and spread of Salmonella enterica.

    PubMed

    Dybowski, Richard; Restif, Olivier; Goupy, Alexandre; Maskell, Duncan J; Mastroeni, Piero; Grant, Andrew J

    2015-12-01

    Intravenous inoculation of Salmonella enterica serovar Typhimurium into mice is a prime experimental model of invasive salmonellosis. The use of wild-type isogenic tagged strains (WITS) in this system has revealed that bacteria undergo independent bottlenecks in the liver and spleen before establishing a systemic infection. We recently showed that those bacteria that survived the bottleneck exhibited enhanced growth when transferred to naive mice. In this study, we set out to disentangle the components of this in vivo adaptation by inoculating mice with WITS grown either in vitro or in vivo. We developed an original method to estimate the replication and killing rates of bacteria from experimental data, which involved solving the probability-generating function of a non-homogeneous birth-death-immigration process. This revealed a low initial mortality in bacteria obtained from a donor animal. Next, an analysis of WITS distributions in the livers and spleens of recipient animals indicated that in vivo-passaged bacteria started spreading between organs earlier than in vitro-grown bacteria. These results further our understanding of the influence of passage in a host on the fitness and virulence of Salmonella enterica and represent an advance in the power of investigation on the patterns and mechanisms of host-pathogen interactions. PMID:26701880

  13. Single passage in mouse organs enhances the survival and spread of Salmonella enterica

    PubMed Central

    Dybowski, Richard; Restif, Olivier; Goupy, Alexandre; Maskell, Duncan J.; Mastroeni, Piero; Grant, Andrew J.

    2015-01-01

    Intravenous inoculation of Salmonella enterica serovar Typhimurium into mice is a prime experimental model of invasive salmonellosis. The use of wild-type isogenic tagged strains (WITS) in this system has revealed that bacteria undergo independent bottlenecks in the liver and spleen before establishing a systemic infection. We recently showed that those bacteria that survived the bottleneck exhibited enhanced growth when transferred to naive mice. In this study, we set out to disentangle the components of this in vivo adaptation by inoculating mice with WITS grown either in vitro or in vivo. We developed an original method to estimate the replication and killing rates of bacteria from experimental data, which involved solving the probability-generating function of a non-homogeneous birth–death–immigration process. This revealed a low initial mortality in bacteria obtained from a donor animal. Next, an analysis of WITS distributions in the livers and spleens of recipient animals indicated that in vivo-passaged bacteria started spreading between organs earlier than in vitro-grown bacteria. These results further our understanding of the influence of passage in a host on the fitness and virulence of Salmonella enterica and represent an advance in the power of investigation on the patterns and mechanisms of host–pathogen interactions. PMID:26701880

  14. Nitrogen-doped graphene: beyond single substitution and enhanced molecular sensing

    PubMed Central

    Lv, Ruitao; Li, Qing; Botello-Méndez, Andrés R.; Hayashi, Takuya; Wang, Bei; Berkdemir, Ayse; Hao, Qingzhen; Elías, Ana Laura; Cruz-Silva, Rodolfo; Gutiérrez, Humberto R.; Kim, Yoong Ahm; Muramatsu, Hiroyuki; Zhu, Jun; Endo, Morinobu; Terrones, Humberto; Charlier, Jean-Christophe; Pan, Minghu; Terrones, Mauricio

    2012-01-01

    Graphene is a two-dimensional network in which sp2-hybridized carbon atoms are arranged in two different triangular sub-lattices (A and B). By incorporating nitrogen atoms into graphene, its physico-chemical properties could be significantly altered depending on the doping configuration within the sub-lattices. Here, we describe the synthesis of large-area, highly-crystalline monolayer N-doped graphene (NG) sheets via atmospheric-pressure chemical vapor deposition, yielding a unique N-doping site composed of two quasi-adjacent substitutional nitrogen atoms within the same graphene sub-lattice (N2AA). Scanning tunneling microscopy and spectroscopy (STM and STS) of NG revealed the presence of localized states in the conduction band induced by N2AA-doping, which was confirmed by ab initio calculations. Furthermore, we demonstrated for the first time that NG could be used to efficiently probe organic molecules via a highly improved graphene enhanced Raman scattering. PMID:22905317

  15. Single passage in mouse organs enhances the survival and spread of Salmonella enterica.

    PubMed

    Dybowski, Richard; Restif, Olivier; Goupy, Alexandre; Maskell, Duncan J; Mastroeni, Piero; Grant, Andrew J

    2015-12-01

    Intravenous inoculation of Salmonella enterica serovar Typhimurium into mice is a prime experimental model of invasive salmonellosis. The use of wild-type isogenic tagged strains (WITS) in this system has revealed that bacteria undergo independent bottlenecks in the liver and spleen before establishing a systemic infection. We recently showed that those bacteria that survived the bottleneck exhibited enhanced growth when transferred to naive mice. In this study, we set out to disentangle the components of this in vivo adaptation by inoculating mice with WITS grown either in vitro or in vivo. We developed an original method to estimate the replication and killing rates of bacteria from experimental data, which involved solving the probability-generating function of a non-homogeneous birth-death-immigration process. This revealed a low initial mortality in bacteria obtained from a donor animal. Next, an analysis of WITS distributions in the livers and spleens of recipient animals indicated that in vivo-passaged bacteria started spreading between organs earlier than in vitro-grown bacteria. These results further our understanding of the influence of passage in a host on the fitness and virulence of Salmonella enterica and represent an advance in the power of investigation on the patterns and mechanisms of host-pathogen interactions.

  16. Enhanced Stability and Controllability of an Ionic Diode Based on Funnel-Shaped Nanochannels with an Extended Critical Region.

    PubMed

    Xiao, Kai; Xie, Ganhua; Zhang, Zhen; Kong, Xiang-Yu; Liu, Qian; Li, Pei; Wen, Liping; Jiang, Lei

    2016-05-01

    The enhanced stability and controllability of an ionic diode system based on funnel-shaped nanochannels with a much longer critical region is reported. The polarity of ion transport switching from anion/cation-selective to ambipolar can be controlled by tuning the length and charge of the critical region. This nanofluidic structure anticipates potential applications in single-molecule biosensing, water resource monitoring, and healthcare.

  17. A Single Nucleotide Polymorphism in Human APOBEC3C Enhances Restriction of Lentiviruses

    PubMed Central

    Wittkopp, Cristina J.; Adolph, Madison B.; Wu, Lily I.; Chelico, Linda; Emerman, Michael

    2016-01-01

    Humans express seven human APOBEC3 proteins, which can inhibit viruses and endogenous retroelements through cytidine deaminase activity. The seven paralogs differ in the potency of their antiviral effects, as well as in their antiviral targets. One APOBEC3, APOBEC3C, is exceptional as it has been found to only weakly block viruses and endogenous retroelements compared to other APOBEC3s. However, our positive selection analyses suggest that APOBEC3C has played a role in pathogen defense during primate evolution. Here, we describe a single nucleotide polymorphism in human APOBEC3C, a change from serine to isoleucine at position 188 (I188) that confers potent antiviral activity against HIV-1. The gain-of-function APOBEC3C SNP results in increased enzymatic activity and hypermutation of target sequences when tested in vitro, and correlates with increased dimerization of the protein. The I188 is widely distributed in human African populations, and is the ancestral primate allele, but is not found in chimpanzees or gorillas. Thus, while other hominids have lost activity of this antiviral gene, it has been maintained, or re-acquired, as a more active antiviral gene in a subset of humans. Taken together, our results suggest that APOBEC3C is in fact involved in protecting hosts from lentiviruses. PMID:27732658

  18. Enhancement of superconductivity under pressure and the magnetic phase diagram of tantalum disulfide single crystals.

    PubMed

    Abdel-Hafiez, M; Zhao, X-M; Kordyuk, A A; Fang, Y-W; Pan, B; He, Z; Duan, C-G; Zhao, J; Chen, X-J

    2016-08-18

    In low-dimensional electron systems, charge density waves (CDW) and superconductivity are two of the most fundamental collective quantum phenomena. For all known quasi-two-dimensional superconductors, the origin and exact boundary of the electronic orderings and superconductivity are still attractive problems. Through transport and thermodynamic measurements, we report on the field-temperature phase diagram in 2H-TaS2 single crystals. We show that the superconducting transition temperature (Tc) increases by one order of magnitude from temperatures at 0.98 K up to 9.15 K at 8.7 GPa when the Tc becomes very sharp. Additionally, the effects of 8.7 GPa illustrate a suppression of the CDW ground state, with critically small Fermi surfaces. Below the Tc the lattice of magnetic flux lines melts from a solid-like state to a broad vortex liquid phase region. Our measurements indicate an unconventional s-wave-like picture with two energy gaps evidencing its multi-band nature.

  19. Enhanced cold wall CVD reactor growth of horizontally aligned single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Mu, Wei; Kwak, Eun-Hye; Chen, Bingan; Huang, Shirong; Edwards, Michael; Fu, Yifeng; Jeppson, Kjell; Teo, Kenneth; Jeong, Goo-Hwan; Liu, Johan

    2016-05-01

    HASynthesis of horizontally-aligned single-walled carbon nanotubes (HA-SWCNTs) by chemical vapor deposition (CVD) directly on quartz seems very promising for the fabrication of future nanoelectronic devices. In comparison to hot-wall CVD, synthesis of HA-SWCNTs in a cold-wall CVD chamber not only means shorter heating, cooling and growth periods, but also prevents contamination of the chamber. However, since most synthesis of HA-SWCNTs is performed in hot-wall reactors, adapting this well-established process to a cold-wall chamber becomes extremely crucial. Here, in order to transfer the CVD growth technology from a hot-wall to a cold-wall chamber, a systematic investigation has been conducted to determine the influence of process parameters on the HA-SWCNT's growth. For two reasons, the cold-wall CVD chamber was upgraded with a top heater to complement the bottom substrate heater; the first reason to maintain a more uniform temperature profile during HA-SWCNTs growth, and the second reason to preheat the precursor gas flow before projecting it onto the catalyst. Our results show that the addition of a top heater had a significant effect on the synthesis. Characterization of the CNTs shows that the average density of HA-SWCNTs is around 1 - 2 tubes/ μm with high growth quality as shown by Raman analysis. [Figure not available: see fulltext.

  20. ENHANCED HYDROGEN PRODUCTION INTEGRATED WITH CO2 SEPARATION IN A SINGLE-STAGE REACTOR

    SciTech Connect

    Himanshu Gupta; Mahesh Iyer; Bartev Sakadjian; Liang-Shih Fan

    2005-03-10

    Hydrogen production cannot be maximized from fossil fuels (gas/coal) via the WGS reaction at high temperatures as the WGS-equilibrium constant K{sub WGS} (= [CO{sub 2}][H{sub 2}]/[CO][H{sub 2}O]), falls with increasing temperatures. However, CO{sub 2} removal down to ppm levels by the carbonation of CaO to CaCO{sub 3} in the temperature range 650-850 C, leads to the possibility of stoichiometric H{sub 2} production at high temperature/pressure conditions and at low steam to fuel ratios. Further, CO{sub 2} is also captured in the H{sub 2} generation process, making this coal to hydrogen process compatible with CO{sub 2} sequestration goals. While microporous CaO sorbents attain <50% conversion over cyclical carbonation-calcination, the OSU-patented, mesoporous CaO sorbents are able to achieve >95% conversion. Novel calcination techniques could lead to an ever-smaller footprint, single-stage reactors that achieve maximum theoretical H{sub 2} production at high temperatures and pressures for on/off site usage. Experimental results indicate that the PCC-CaO sorbent is able to achieve complete conversion of CO for 240 seconds as compared to only a few seconds with CaO derived from natural sources.

  1. Enhancement of superconductivity under pressure and the magnetic phase diagram of tantalum disulfide single crystals.

    PubMed

    Abdel-Hafiez, M; Zhao, X-M; Kordyuk, A A; Fang, Y-W; Pan, B; He, Z; Duan, C-G; Zhao, J; Chen, X-J

    2016-01-01

    In low-dimensional electron systems, charge density waves (CDW) and superconductivity are two of the most fundamental collective quantum phenomena. For all known quasi-two-dimensional superconductors, the origin and exact boundary of the electronic orderings and superconductivity are still attractive problems. Through transport and thermodynamic measurements, we report on the field-temperature phase diagram in 2H-TaS2 single crystals. We show that the superconducting transition temperature (Tc) increases by one order of magnitude from temperatures at 0.98 K up to 9.15 K at 8.7 GPa when the Tc becomes very sharp. Additionally, the effects of 8.7 GPa illustrate a suppression of the CDW ground state, with critically small Fermi surfaces. Below the Tc the lattice of magnetic flux lines melts from a solid-like state to a broad vortex liquid phase region. Our measurements indicate an unconventional s-wave-like picture with two energy gaps evidencing its multi-band nature. PMID:27534898

  2. Single-walled carbon nanotubes functionalized with sodium hyaluronate enhance bone mineralization.

    PubMed

    Sá, M A; Ribeiro, H J; Valverde, T M; Sousa, B R; Martins-Júnior, P A; Mendes, R M; Ladeira, L O; Resende, R R; Kitten, G T; Ferreira, A J

    2016-02-01

    The aim of this study was to evaluate the effects of sodium hyaluronate (HY), single-walled carbon nanotubes (SWCNTs) and HY-functionalized SWCNTs (HY-SWCNTs) on the behavior of primary osteoblasts, as well as to investigate the deposition of inorganic crystals on titanium surfaces coated with these biocomposites. Primary osteoblasts were obtained from the calvarial bones of male newborn Wistar rats (5 rats for each cell extraction). We assessed cell viability using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide assay and by double-staining with propidium iodide and Hoechst. We also assessed the formation of mineralized bone nodules by von Kossa staining, the mRNA expression of bone repair proteins, and the deposition of inorganic crystals on titanium surfaces coated with HY, SWCNTs, or HY-SWCNTs. The results showed that treatment with these biocomposites did not alter the viability of primary osteoblasts. Furthermore, deposition of mineralized bone nodules was significantly increased by cells treated with HY and HY-SWCNTs. This can be partly explained by an increase in the mRNA expression of type I and III collagen, osteocalcin, and bone morphogenetic proteins 2 and 4. Additionally, the titanium surface treated with HY-SWCNTs showed a significant increase in the deposition of inorganic crystals. Thus, our data indicate that HY, SWCNTs, and HY-SWCNTs are potentially useful for the development of new strategies for bone tissue engineering.

  3. Single-walled carbon nanotubes functionalized with sodium hyaluronate enhance bone mineralization

    PubMed Central

    Sá, M.A.; Ribeiro, H.J.; Valverde, T.M.; Sousa, B.R.; Martins-Júnior, P.A.; Mendes, R.M.; Ladeira, L.O.; Resende, R.R.; Kitten, G.T.; Ferreira, A.J.

    2015-01-01

    The aim of this study was to evaluate the effects of sodium hyaluronate (HY), single-walled carbon nanotubes (SWCNTs) and HY-functionalized SWCNTs (HY-SWCNTs) on the behavior of primary osteoblasts, as well as to investigate the deposition of inorganic crystals on titanium surfaces coated with these biocomposites. Primary osteoblasts were obtained from the calvarial bones of male newborn Wistar rats (5 rats for each cell extraction). We assessed cell viability using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide assay and by double-staining with propidium iodide and Hoechst. We also assessed the formation of mineralized bone nodules by von Kossa staining, the mRNA expression of bone repair proteins, and the deposition of inorganic crystals on titanium surfaces coated with HY, SWCNTs, or HY-SWCNTs. The results showed that treatment with these biocomposites did not alter the viability of primary osteoblasts. Furthermore, deposition of mineralized bone nodules was significantly increased by cells treated with HY and HY-SWCNTs. This can be partly explained by an increase in the mRNA expression of type I and III collagen, osteocalcin, and bone morphogenetic proteins 2 and 4. Additionally, the titanium surface treated with HY-SWCNTs showed a significant increase in the deposition of inorganic crystals. Thus, our data indicate that HY, SWCNTs, and HY-SWCNTs are potentially useful for the development of new strategies for bone tissue engineering. PMID:26648087

  4. Enhancement of superconductivity under pressure and the magnetic phase diagram of tantalum disulfide single crystals

    PubMed Central

    Abdel-Hafiez, M.; Zhao, X.-M.; Kordyuk, A. A.; Fang, Y.-W.; Pan, B.; He, Z.; Duan, C.-G.; Zhao, J.; Chen, X.-J.

    2016-01-01

    In low-dimensional electron systems, charge density waves (CDW) and superconductivity are two of the most fundamental collective quantum phenomena. For all known quasi-two-dimensional superconductors, the origin and exact boundary of the electronic orderings and superconductivity are still attractive problems. Through transport and thermodynamic measurements, we report on the field-temperature phase diagram in 2H-TaS2 single crystals. We show that the superconducting transition temperature (Tc) increases by one order of magnitude from temperatures at 0.98 K up to 9.15 K at 8.7 GPa when the Tc becomes very sharp. Additionally, the effects of 8.7 GPa illustrate a suppression of the CDW ground state, with critically small Fermi surfaces. Below the Tc the lattice of magnetic flux lines melts from a solid-like state to a broad vortex liquid phase region. Our measurements indicate an unconventional s-wave-like picture with two energy gaps evidencing its multi-band nature. PMID:27534898

  5. Enhancement of superconductivity under pressure and the magnetic phase diagram of tantalum disulfide single crystals

    NASA Astrophysics Data System (ADS)

    Abdel-Hafiez, M.; Zhao, X.-M.; Kordyuk, A. A.; Fang, Y.-W.; Pan, B.; He, Z.; Duan, C.-G.; Zhao, J.; Chen, X.-J.

    2016-08-01

    In low-dimensional electron systems, charge density waves (CDW) and superconductivity are two of the most fundamental collective quantum phenomena. For all known quasi-two-dimensional superconductors, the origin and exact boundary of the electronic orderings and superconductivity are still attractive problems. Through transport and thermodynamic measurements, we report on the field-temperature phase diagram in 2H-TaS2 single crystals. We show that the superconducting transition temperature (Tc) increases by one order of magnitude from temperatures at 0.98 K up to 9.15 K at 8.7 GPa when the Tc becomes very sharp. Additionally, the effects of 8.7 GPa illustrate a suppression of the CDW ground state, with critically small Fermi surfaces. Below the Tc the lattice of magnetic flux lines melts from a solid-like state to a broad vortex liquid phase region. Our measurements indicate an unconventional s-wave-like picture with two energy gaps evidencing its multi-band nature.

  6. Single-step preparation and deagglomeration of itraconazole microflakes by supercritical antisolvent method for dissolution enhancement.

    PubMed

    Sathigari, Sateesh Kumar; Ober, Courtney A; Sanganwar, Ganesh P; Gupta, Ram B; Babu, R Jayachandra

    2011-07-01

    Itraconazole (ITZ) microflakes were produced by supercritical antisolvent (SAS) method and simultaneously mixed with pharmaceutical excipients in a single step to prevent drug agglomeration. Simultaneous ITZ particle formation and mixing with fast-flo lactose (FFL) was performed in a high-pressure stirred vessel at 116 bar and 40 °C by the SAS-drug excipient mixing (SAS-DEM) method. The effects of stabilizers, such as sodium dodecyl sulfate and poloxamer 407 (PLX), on particle formation and drug dissolution were studied. Drug-excipient formulations were characterized for surface morphology, crystallinity, drug-excipient interactions, drug content uniformity, and drug dissolution rate. Mixture of drug microflakes and FFL formed by the SAS-DEM process shows that the process was successful in overcoming drug-drug agglomeration. PLX produced crystalline drug flakes in loose agglomerates with superior dissolution and flow properties even at higher drug loadings. Characterization studies confirmed the crystallinity of the drug and absence of chemical interactions during the SAS process. The dissolution of ITZ was substantially higher due to SAS and SAS-DEM processes; this improvement can be attributed to the microflake particle structures, effective deagglomeration, and wetting of the drug flakes with the excipients.

  7. A Pilot Study of the Feasibility and Efficacy of the Strategies to Enhance Positive Parenting (STEPP) Program for Single Mothers of Children with ADHD

    ERIC Educational Resources Information Center

    Chacko, Anil; Wymbs, Brian T.; Flammer-Rivera, Lizette M.; Pelham, William E.; Walker, Kathryn S.; Arnold, Fran W.; Visweswaraiah, Hema; Swanger-Gagne, Michelle; Girio, Erin L.; Pirvics, Lauma L.; Herbst, Laura

    2008-01-01

    Objective: The Strategies to Enhance Positive Parenting (STEPP) program was developed to address putative factors related to poor engagement in and outcomes following traditional behavioral parent training (BPT) for single mothers of children diagnosed with ADHD. Method: Twelve single mothers of children with ADHD were enrolled in an initial…

  8. Heat transfer of R-134a in single-tube spray evaporation including lubricant effects and enhanced surface results

    SciTech Connect

    Moeykens, S.A.; Huebsch, W.W.; Pate, M.B.

    1995-08-01

    Single-tube spray evaporation experimental tests were conducted in order to evaluate the average wall heat transfer coefficients for seven different commercially available tubes. Liquid film supply rates were held constant in order to evaluate the effects of the enhancement on shell-side heat transfer under similar conditions. Because the spray evaporation phenomenon is so different from pool boiling, both condensation-type and evaporation-type enhanced surfaces were evaluated. A comparison of the results for all of the tubes showed that the enhanced condensation surfaces performed better than the enhanced boiling surfaces. In addition, the 26-fpi surface tested marginally better than the 40-fpi surface. Small concentrations of a polyol-ester lubricant cause a foaming effect that increases the heat transfer performance. This tendency was seen with both 32-cs and 68-cs polyol-ester oils. The 68-cs lubricant was tested at concentrations of 0.0, 0.5, 1.0, 3.0, and 5.0 with the W-40 fpi and Tu-Cii surfaces. Results with this lubricant show the performance continues to increase through the 3% concentration for most of the heat flux range tested At the upper end of the range tested, the 1.0% mass fraction yielded the best performance. The 32-cs lubricant generated trends similar to those of the 68-cs lubricant. Lubricant concentrations of 1.0%, 2.0%, and 3.0% were evaluated with plain, W-40 fpi, and Tu-Cii surfaces. The 2.0% concentration, not the 1.0 %, generated the best performance at the highest heat flux tested. This difference must be attributed to the difference in the lubricant viscosity.

  9. Single and Multi-Channel Carbon-based Quantum Dragons

    NASA Astrophysics Data System (ADS)

    Inkoom, Godfred; Abdurazakov, Omadillo; Novotny, Mark

    2015-03-01

    In the coherent regime for electrical conductance measurements, two semi-infinite leads are connected to a finite nanostructure, and the nano-device conductance is calculated using the Landauer formula. Any channel k that has transmission for electrons with energy E, \\calTk (E) =1 contributes the conductance quantum G0 = 2e2 / h . Any nano-device with at least one \\calTk (E) =1 is called a quantum dragon. The transmission probability \\calTk (E) can be obtained from the solution of the time-independent Schrödinger equation. Uniform leads connected to armchair single-walled carbon nanotubes (SWCNTs) have calT (E) =1, while when connected to zigzag SWCNT the calT (E) is less than unity. Appropriately dimerized leads connected to zigzag SWCNTs are quantum dragons, while when connected to armchair SWCNTs calT (E) is less than unity. We have generalized the matrix method and mapping methods of in order to investigate SWCNTs that can be multi-channel quantum dragons. For example, one can use armchair SWCNT leads to connect to an armchair SWCNT to try to produce a multi-channel quantum dragon. Supported in part by NSF Grant DMR-1206233.

  10. Micromotion based single-qubit addressing with trapped-ions

    NASA Astrophysics Data System (ADS)

    Akerman, Nitzan; Navon, Nir; Kotler, Shlomi; Glickman, Yinnon; Almog, Ido; Ozeri, Roee

    2013-05-01

    Individual-particle addressing is a necessary capability in many quantum information experiments. For example, characterization of multi-qubit operations with quantum process tomography (QPT). We propose and demonstrate a scheme that exploits the inhomogeneous excess micromotion in ion trap to address single-qubits in a chain of several ion-qubits, separated by only few microns. The scheme uses a laser field which is resonant with the micromotion sideband of a narrow optical quadrupole transition and acts as a dressing field with a spatially-dependent coupling along the chain. As a consequence, the level spacing of each ion, in the dressed state picture, becomes position dependent and individual ions can be spectrally separated. We have demonstrated Individual Rabi flops with 85% fidelity in a three-ion chain. For the case of only two ions, the coupling can be tailored to vanish on one of the two. This allows preparing any two-qubit product state as well as completing state tomography without direct spatially-selective imaging. We demonstrate full QPT for two-qubit Sørensen-Mølmer entangling interaction (Bell-state preparation fidelity of 98%) which has not been process-analyzed yet. Our tomography resulted process fidelity of 92%. N. Navon et al. arXiv:1210.7336 (1012).

  11. Risk-based planning analysis for a single levee

    NASA Astrophysics Data System (ADS)

    Hui, Rui; Jachens, Elizabeth; Lund, Jay

    2016-04-01

    Traditional risk-based analysis for levee planning focuses primarily on overtopping failure. Although many levees fail before overtopping, few planning studies explicitly include intermediate geotechnical failures in flood risk analysis. This study develops a risk-based model for two simplified levee failure modes: overtopping failure and overall intermediate geotechnical failure from through-seepage, determined by the levee cross section represented by levee height and crown width. Overtopping failure is based only on water level and levee height, while through-seepage failure depends on many geotechnical factors as well, mathematically represented here as a function of levee crown width using levee fragility curves developed from professional judgment or analysis. These levee planning decisions are optimized to minimize the annual expected total cost, which sums expected (residual) annual flood damage and annualized construction costs. Applicability of this optimization approach to planning new levees or upgrading existing levees is demonstrated preliminarily for a levee on a small river protecting agricultural land, and a major levee on a large river protecting a more valuable urban area. Optimized results show higher likelihood of intermediate geotechnical failure than overtopping failure. The effects of uncertainty in levee fragility curves, economic damage potential, construction costs, and hydrology (changing climate) are explored. Optimal levee crown width is more sensitive to these uncertainties than height, while the derived general principles and guidelines for risk-based optimal levee planning remain the same.

  12. The AI Interdisciplinary Context: Single or Multiple Research Bases?

    ERIC Educational Resources Information Center

    Khawam, Yves J.

    1992-01-01

    This study used citation analysis to determine whether the disciplines contributing to the journal literature of artificial intelligence (AI)--philosophy, psychology, linguistics, computer science, and engineering--share a common AI research base. The idea that AI consists of a completely interdisciplinary endeavor was refuted. (MES)

  13. A single enhancer regulating the differential expression of duplicated red-sensitive opsin genes in zebrafish.

    PubMed

    Tsujimura, Taro; Hosoya, Tomohiro; Kawamura, Shoji

    2010-12-16

    A fundamental step in the evolution of the visual system is the gene duplication of visual opsins and differentiation between the duplicates in absorption spectra and expression pattern in the retina. However, our understanding of the mechanism of expression differentiation is far behind that of spectral tuning of opsins. Zebrafish (Danio rerio) have two red-sensitive cone opsin genes, LWS-1 and LWS-2. These genes are arrayed in a tail-to-head manner, in this order, and are both expressed in the long member of double cones (LDCs) in the retina. Expression of the longer-wave sensitive LWS-1 occurs later in development and is thus confined to the peripheral, especially ventral-nasal region of the adult retina, whereas expression of LWS-2 occurs earlier and is confined to the central region of the adult retina, shifted slightly to the dorsal-temporal region. In this study, we employed a transgenic reporter assay using fluorescent proteins and P1-artificial chromosome (PAC) clones encompassing the two genes and identified a 0.6-kb "LWS-activating region" (LAR) upstream of LWS-1, which regulates expression of both genes. Under the 2.6-kb flanking upstream region containing the LAR, the expression pattern of LWS-1 was recapitulated by the fluorescent reporter. On the other hand, when LAR was directly conjugated to the LWS-2 upstream region, the reporter was expressed in the LDCs but also across the entire outer nuclear layer. Deletion of LAR from the PAC clones drastically lowered the reporter expression of the two genes. These results suggest that LAR regulates both LWS-1 and LWS-2 by enhancing their expression and that interaction of LAR with the promoters is competitive between the two genes in a developmentally restricted manner. Sharing a regulatory region between duplicated genes could be a general way to facilitate the expression differentiation in duplicated visual opsins.

  14. Optical fiber tip-based quartz-enhanced photoacoustic sensor for trace gas detection

    NASA Astrophysics Data System (ADS)

    Li, Zhili; Wang, Zhen; Wang, Chao; Ren, Wei

    2016-05-01

    We reported the development of an evanescent-wave quartz-enhanced photoacoustic sensor (EW-QEPAS) using a single-mode optical fiber tip for sensitive gas detection in the extended near-infrared region. It is a spectroscopic technique based on the combination of quartz-enhanced photoacoustic spectroscopy with fiber-optic evanescent-wave absorption to achieve low optical noise, easy optical alignment, and high compactness. Carbon monoxide (CO) detection at 2.3 μm using a fiber-coupled, continuous-wave, distributed-feedback laser was selected for the sensor demonstration. By tapering the optical fiber down to 2.5 μm diameter using the flame-brushing technique, an evanescent field of ~0.6 mW around the fiber tip was absorbed by CO molecules. Besides an excellent linear response ( R 2 = 0.9996) to CO concentrations, the EW-QEPAS sensor achieved a normalized noise-equivalent absorption (NNEA) coefficient of 8.6 × 10-8 cm-1W/√Hz for an incident optical power of 1.8 mW and integration time of 1 s. The sensor detection sensitivity can be further improved by enhancing the evanescent-wave power on the fiber tip.

  15. Speech enhancement using an equivalent source inverse filtering-based microphone array.

    PubMed

    Bai, Mingsian R; Hur, Kur-Nan; Liu, Ying-Ting

    2010-03-01

    This paper presents a microphone array technique aimed at enhancing speech quality in a reverberant environment. This technique is based on the central idea of single-input-multiple-output equivalent source inverse filtering (SIMO-ESIF). The inverse filters required by the time-domain processing in the technique serve two purposes: de-reverberation and noise reduction. The proposed approach could be useful in telecommunication applications such as automotive hands-free systems, where noise-corrupted speech signal generally needs to be enhanced. SIMO-ESIF can be further enhanced against uncertainties and perturbations by including an adaptive generalized side-lobe canceller. The system is implemented and validated experimentally in a car. As indicated by numerous performance measures, the proposed system proved effective in reducing noise in human speech without significantly compromising the speech quality. In addition, listening tests were conducted to assess the subjective performance of the proposed system, with results processed by using the analysis of variance and a post hoc Fisher's least significant difference (LSD) test to assess the pairwise difference between the noise reduction (NR) algorithms.

  16. Color enhancement and image defogging in HSI based on Retinex model

    NASA Astrophysics Data System (ADS)

    Gao, Han; Wei, Ping; Ke, Jun

    2015-08-01

    Retinex is a luminance perceptual algorithm based on color consistency. It has a good performance in color enhancement. But in some cases, the traditional Retinex algorithms, both Single-Scale Retinex(SSR) and Multi-Scale Retinex(MSR) in RGB color space, do not work well and will cause color deviation. To solve this problem, we present improved SSR and MSR algorithms. Compared to other Retinex algorithms, we implement Retinex algorithms in HSI(Hue, Saturation, Intensity) color space, and use a parameter αto improve quality of the image. Moreover, the algorithms presented in this paper has a good performance in image defogging. Contrasted with traditional Retinex algorithms, we use intensity channel to obtain reflection information of an image. The intensity channel is processed using a Gaussian center-surround image filter to get light information, which should be removed from intensity channel. After that, we subtract the light information from intensity channel to obtain the reflection image, which only includes the attribute of the objects in image. Using the reflection image and a parameter α, which is an arbitrary scale factor set manually, we improve the intensity channel, and complete the color enhancement. Our experiments show that this approach works well compared with existing methods for color enhancement. Besides a better performance in color deviation problem and image defogging, a visible improvement in the image quality for human contrast perception is also observed.

  17. Dual-carbon enhanced silicon-based composite as superior anode material for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Wang, Jie; Liu, Dai-Huo; Wang, Ying-Ying; Hou, Bao-Hua; Zhang, Jing-Ping; Wang, Rong-Shun; Wu, Xing-Long

    2016-03-01

    Dual-carbon enhanced Si-based composite (Si/C/G) has been prepared via employing the widely distributed, low-cost and environmentally friendly Diatomite mineral as silicon raw material. The preparation processes are very simple, non-toxic and easy to scale up. Electrochemical tests as anode material for lithium ion batteries (LIBs) demonstrate that this Si/C/G composite exhibits much improved Li-storage properties in terms of superior high-rate capabilities and excellent cycle stability compared to the pristine Si material as well as both single-carbon modified composites. Specifically for the Si/C/G composite, it can still deliver a high specific capacity of about 470 mAh g-1 at an ultrahigh current density of 5 A g-1, and exhibit a high capacity of 938 mAh g-1 at 0.1 A g-1 with excellent capacity retention in the following 300 cycles. The significantly enhanced Li-storage properties should be attributed to the co-existence of both highly conductive graphite and amorphous carbon in the Si/C/G composite. While the former can enhance the electrical conductivity of the obtained composite, the latter acts as the adhesives to connect the porous Si particulates and conductive graphite flakes to form robust and stable conductive network.

  18. A single-point mutation enhances dual functionality of a scorpion toxin.

    PubMed

    Wang, Xueli; Gao, Bin; Zhu, Shunyi

    2016-01-01

    Scorpion venom represents a tremendous, hitherto partially explored peptide library that has been proven to be useful not only for understanding ion channels but also for drug design. MeuTXKα3 is a functionally unknown scorpion toxin-like peptide. Here we describe new transcripts of this gene arising from alternative polyadenylation and its biological function as well as a mutant with a single-point substitution at site 30. Native-like MeuTXKα3 and its mutant were produced in Escherichia coli and their toxic function against Drosophila Shaker K(+) channel and its mammalian counterparts (rKv1.1-rKv1.3) were assayed by two-electrode voltage clamp technique. The results show that MeuTXKα3 is a weak toxin with a wide-spectrum of activity on both Drosophila and mammalian K(+) channels. The substitution of a proline at site 30 by an asparagine, an evolutionarily conserved functional residue in the scorpion α-KTx family, led to an increased activity on rKv1.2 and rKv1.3 but a decreased activity on the Shaker channel without changing the potency on rKv1.1, suggesting a key role of this site in species selectivity of scorpion toxins. MeuTXKα3 was also active on a variety of bacteria with lethal concentrations ranging from 4.66 to 52.01μM and the mutant even had stronger activity on some of these bacterial species. To the best of our knowledge, this is the first report on a bi-functional short-chain peptide in the lesser Asian scorpion venom. Further extensive mutations of MeuTXKα3 at site 30 could help improve its K(+) channel-blocking and antibacterial functions.

  19. Enhanced pulsar and single pulse detection via automated radio frequency interference detection in multipixel feeds

    NASA Astrophysics Data System (ADS)

    Kocz, J.; Bailes, M.; Barnes, D.; Burke-Spolaor, S.; Levin, L.

    2012-02-01

    Single pixel feeds on large aperture radio telescopes have the ability to detect weak (˜10 mJy) impulsive bursts of radio emission and sub-mJy radio pulsars. Unfortunately, in large-scale blind surveys, radio frequency interference (RFI) mimics both radio bursts and radio pulsars, greatly reducing the sensitivity to new discoveries as real signals of astronomical origin get lost among the millions of false candidates. In this paper a technique that takes advantage of multipixel feeds to use eigenvector decomposition of common signals is used to greatly facilitate radio burst and pulsar discovery. Since the majority of RFI occurs with zero dispersion, the method was tested on the total power present in the 13 beams of the Parkes multibeam receiver using data from archival intermediate-latitude surveys. The implementation of this method greatly reduced the number of false candidates and led to the discovery of one new rotating radio transient or RRAT, six new pulsars and five new pulses that shared the swept-frequency characteristics similar in nature to the `Lorimer burst'. These five new signals occurred within minutes of 11 previous detections of a similar type. When viewed together, they display temporal characteristics related to integer seconds, with non-random distributions and characteristic 'gaps' between them, suggesting they are not from a naturally occurring source. Despite the success in removing RFI, false candidates present in the data that are only visible after integrating in time or at non-zero dispersion remained. It is demonstrated that with some computational penalty, the method can be applied iteratively at all trial dispersions and time resolutions to remove the vast majority of spurious candidates.

  20. Spectroscopy-Based Characterization of Single Wall Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Namkung, Min; Namkung, Juock S.; Wincheski, Russell A.; Seo, J.; Park, Cheol

    2003-01-01

    We present the initial results of our combined investigation of Raman scattering and optical absorption spectroscopy in a batch of single wall carbon nanotubes (SWNTs). The SWNT diameters are first estimated from the four radial breathing mode (RBM) peaks using a simple relation of omega(sub RBM) = 248/cm nm/d(sub t)(nm). The calculated diameter values are related to the optical absorption peaks through the expressions of first interband transition energies, i.e., E(sup S)(sub 11) = 2a gamma/d(sub t) for semiconducting and E(sup S)(sub 11) = 6a gamma/d(sub t) for metallic SWNTs, respectively, where a is the carbon-carbon bond length (0.144 nm) and gamma is the energy of overlapping electrons from nearest neighbor atoms, which is 2.9 eV for a SWNT. This analysis indicates that three RBM peaks are from semiconducting tubes, and the remaining one is from metallic tubes. The detailed analysis in the present study is focused on these three peaks of the first absorption band by determining the values of the representative (n,m) pairs. The first step of analysis is to construct a list of possible (n,m) pairs from the diameters calculated from the positions of the RBM peaks. The second step is to compute the first interband transition energy, E(sub 11), by substituting the constructed list of (n,m) into the expression of Reich and Thomsen, and Saito et al. Finally, the pairs with the energies closest to the experimental values are selected.