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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. Laser Induced Breakdown Spectroscopy Based on Single Beam Splitting and Geometric Configuration for Effective Signal Enhancement

    PubMed Central

    Yang, Guang; Lin, Qingyu; Ding, Yu; Tian, Di; Duan, Yixiang

    2015-01-01

    A new laser induced breakdown spectroscopy (LIBS) based on single-beam-splitting (SBS) and proper optical geometric configuration has been initially explored in this work for effective signal enhancement. In order to improve the interaction efficiency of laser energy with the ablated material, a laser beam operated in pulse mode was divided into two streams to ablate/excite the target sample in different directions instead of the conventional one beam excitation in single pulse LIBS (SP-LIBS). In spatial configuration, the laser beam geometry plays an important role in the emission signal enhancement. Thus, an adjustable geometric configuration with variable incident angle between the two splitted laser beams was constructed for achieving maximum signal enhancement. With the optimized angles of 60° and 70° for Al and Cu atomic emission lines at 396.15 nm and 324.75 nm respectively, about 5.6- and 4.8-folds signal enhancements were achieved for aluminum alloy and copper alloy samples compared to SP-LIBS. Furthermore, the temporal analysis, in which the intensity of atomic lines in SP-LIBS decayed at least ten times faster than the SBS-LIBS, proved that the energy coupling efficiency of SBS-LIBS was significantly higher than that of SP-LIBS. PMID:25557721

  3. Laser induced breakdown spectroscopy based on single beam splitting and geometric configuration for effective signal enhancement.

    PubMed

    Yang, Guang; Lin, Qingyu; Ding, Yu; Tian, Di; Duan, Yixiang

    2015-01-05

    A new laser induced breakdown spectroscopy (LIBS) based on single-beam-splitting (SBS) and proper optical geometric configuration has been initially explored in this work for effective signal enhancement. In order to improve the interaction efficiency of laser energy with the ablated material, a laser beam operated in pulse mode was divided into two streams to ablate/excite the target sample in different directions instead of the conventional one beam excitation in single pulse LIBS (SP-LIBS). In spatial configuration, the laser beam geometry plays an important role in the emission signal enhancement. Thus, an adjustable geometric configuration with variable incident angle between the two splitted laser beams was constructed for achieving maximum signal enhancement. With the optimized angles of 60° and 70° for Al and Cu atomic emission lines at 396.15 nm and 324.75 nm respectively, about 5.6- and 4.8-folds signal enhancements were achieved for aluminum alloy and copper alloy samples compared to SP-LIBS. Furthermore, the temporal analysis, in which the intensity of atomic lines in SP-LIBS decayed at least ten times faster than the SBS-LIBS, proved that the energy coupling efficiency of SBS-LIBS was significantly higher than that of SP-LIBS.

  4. Piezoelectric peptide-based nanogenerator enhanced by single-electrode triboelectric nanogenerator

    NASA Astrophysics Data System (ADS)

    Nguyen, Vu; Kelly, Steve; Yang, Rusen

    2017-07-01

    Peptide has recently been demonstrated as a sustainable and smart material for piezoelectric energy conversion. Although the power output was improved compared to other biomaterials, the use of a piezoelectric device alone can only capture the energy from the minute deformation in materials. In comparison, the triboelectric effect can convert mechanical energy from large motion. Consequently, utilizing both piezoelectric and triboelectric effects is of significant research interest due to their complementary energy conversion mechanisms. Here we demonstrated a hybrid nanogenerator that combined a peptide-based piezoelectric nanogenerator with a single-electrode triboelectric nanogenerator. Our device structure enabled the voltage and current outputs of each individual type of nanogenerator to be superposed in the hybrid nanogenerator, producing overall constructive outputs. The design of our device also enabled a simplified configuration of hybrid nanogenerator. This study is important not only for the enhancement of peptide-based piezoelectric device but also for the future design of hybrid piezoelectric and triboelectric nanogenerators.

  5. 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

  6. 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.

  7. Platinum plasmonic nanostructure arrays for massively parallel single-molecule detection based on enhanced fluorescence measurements.

    PubMed

    Saito, Toshiro; Takahashi, Satoshi; Obara, Takayuki; Itabashi, Naoshi; Imai, Kazumichi

    2011-11-04

    We fabricated platinum bowtie nanostructure arrays producing fluorescence enhancement and evaluated their performance using two-photon photoluminescence and single-molecule fluorescence measurements. A comprehensive selection of suitable materials was explored by electromagnetic simulation and Pt was chosen as the plasmonic material for visible light excitation near 500 nm, which is preferable for multicolor dye-labeling applications like DNA sequencing. The observation of bright photoluminescence (λ = 500-600 nm) from each Pt nanostructure, induced by irradiation at 800 nm with a femtosecond laser pulse, clearly indicates that a highly enhanced local field is created near the Pt nanostructure. The attachment of a single dye molecule was attempted between the Pt triangles of each nanostructure by using selective immobilization chemistry. The fluorescence intensities of the single dye molecule localized on the nanostructures were measured. A highly enhanced fluorescence, which was increased by a factor of 30, was observed. The two-photon photoluminescence intensity and fluorescence intensity showed qualitatively consistent gap size dependence. However, the average fluorescence enhancement factor was rather repressed even in the nanostructure with the smallest gap size compared to the large growth of photoluminescence. The variation of the position of the dye molecule attached to the nanostructure may influence the wide distribution of the fluorescence enhancement factor and cause the rather small average value of the fluorescence enhancement factor.

  8. Genome-wide assessment of sequence-intrinsic enhancer responsiveness at single-base-pair resolution.

    PubMed

    Arnold, Cosmas D; Zabidi, Muhammad A; Pagani, Michaela; Rath, Martina; Schernhuber, Katharina; Kazmar, Tomáš; Stark, Alexander

    2017-02-01

    Gene expression is controlled by enhancers that activate transcription from the core promoters of their target genes. Although a key function of core promoters is to convert enhancer activities into gene transcription, whether and how strongly they activate transcription in response to enhancers has not been systematically assessed on a genome-wide level. Here we describe self-transcribing active core promoter sequencing (STAP-seq), a method to determine the responsiveness of genomic sequences to enhancers, and apply it to the Drosophila melanogaster genome. We cloned candidate fragments at the position of the core promoter (also called minimal promoter) in reporter plasmids with or without a strong enhancer, transfected the resulting library into cells, and quantified the transcripts that initiated from each candidate for each setup by deep sequencing. In the presence of a single strong enhancer, the enhancer responsiveness of different sequences differs by several orders of magnitude, and different levels of responsiveness are associated with genes of different functions. We also identify sequence features that predict enhancer responsiveness and discuss how different core promoters are employed for the regulation of gene expression.

  9. Wavelength tunable single nanowire lasers based on surface plasmon polariton enhanced Burstein-Moss effect.

    PubMed

    Liu, Xinfeng; Zhang, Qing; Yip, Jing Ngei; Xiong, Qihua; Sum, Tze Chien

    2013-01-01

    Wavelength tunable semiconductor nanowire (NW) lasers are promising for multifunctional applications ranging from optical communication to spectroscopy analysis. Here, we present a demonstration of utilizing the surface plasmon polariton (SPP) enhanced Burstein-Moss (BM) effect to tune the lasing wavelength of a single semiconductor NW. The photonic lasing mode of the CdS NW (with length ~10 μm and diameter ~220 nm) significantly blue shifts from 504 to 483 nm at room temperature when the NW is in close proximity to the Au film. Systematic steady state power dependent photoluminescence (PL) and time-resolved PL studies validate that the BM effect in the hybrid CdS NW devices is greatly enhanced as a consequence of the strong coupling between the SPP and CdS excitons. With decreasing dielectric layer thickness h from 100 to 5 nm, the enhancement of the BM effect becomes stronger, leading to a larger blue shift of the lasing wavelength. Measurements of enhanced exciton emission intensities and recombination rates in the presence of Au film further support the strong interaction between SPP and excitons, which is consistent with the simulation results.

  10. Cavity-Enhanced Single-Photon Source Based on the Silicon-Vacancy Center in Diamond

    NASA Astrophysics Data System (ADS)

    Benedikter, Julia; Kaupp, Hanno; Hümmer, Thomas; Liang, Yuejiang; Bommer, Alexander; Becher, Christoph; Krueger, Anke; Smith, Jason M.; Hänsch, Theodor W.; Hunger, David

    2017-02-01

    Single-photon sources are an integral part of various quantum technologies, and solid-state quantum emitters at room temperature appear to be a promising implementation. We couple the fluorescence of individual silicon-vacancy centers in nanodiamonds to a tunable optical microcavity to demonstrate a single-photon source with high efficiency, increased emission rate, and improved spectral purity compared to the intrinsic emitter properties. We use a fiber-based microcavity with a mode volume as small as 3.4 λ3 and a quality factor of 1.9 ×1 04 and observe an effective Purcell factor of up to 9.2. Furthermore, we study modifications of the internal rate dynamics and propose a rate model that closely agrees with the measurements. We observe lifetime changes of up to 31%, limited by the finite quantum efficiency of the emitters studied here. With improved materials, our achieved parameters predict single-photon rates beyond 1 GHz.

  11. Insulating NiO enhanced MgZnO-based single-barrier 340 nm photodetector

    NASA Astrophysics Data System (ADS)

    Wang, Lei; Gu, Dawei; Shen, Linjiang

    2017-10-01

    Combining pulsed laser deposition and thermal oxidation techniques, an enhanced MgZnO-based photodetector was achieved by inserting an insulating NiO layer between Au electrode and the Mg0.21Zn0.79O active layer. Bias voltage dependent spectral response of the Au/NiO/MgZnO/In photodetector was investigated systematically and it exhibited a peak response of 340 nm with a cutoff wavelength at 355 nm. Under reverse bias, a negative differential resistance feature was observed in the dark and light current-voltage characteristic curves.

  12. 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.

  13. Enhancement of single guide RNA transcription for efficient CRISPR/Cas-based genomic engineering.

    PubMed

    Ui-Tei, Kumiko; Maruyama, Shohei; Nakano, Yuko

    2017-01-26

    Genomic engineering using clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated (Cas) protein is a promising approach for targeting the genomic DNA of virtually any organism in a sequence-specific manner. Recent remarkable advances in CRISPR/Cas technology have made it a feasible system for use in therapeutic applications and biotechnology. In the CRISPR/Cas system, a guide RNA (gRNA), interacting with the Cas protein, recognizes a genomic region with sequence complementarity, and the double-stranded DNA at the target site is cleaved by the Cas protein. A widely used gRNA is an RNA polymerase III (pol III)-driven single gRNA (sgRNA), which is produced by artificial fusion of CRISPR RNA (crRNA) and trans-activation crRNA (tracrRNA). However, we identified a TTTT stretch, known as a termination signal of RNA pol III, in the scaffold region of the sgRNA. Here, we revealed that sgRNA carrying a TTTT stretch reduces the efficiency of sgRNA transcription due to premature transcriptional termination, and decreases the efficiency of genome editing. Unexpectedly, it was also shown that the premature terminated sgRNA may have an adverse effect of inducing RNA interference. Such disadvantageous effects were avoided by substituting one base in the TTTT stretch.

  14. Quantitative surface-enhanced Raman spectroscopy of single bases in oligodeoxynucleotides.

    PubMed

    Dick, S; Bell, S E J

    2017-09-11

    To address the question of whether the SERS signals of ss-DNA are simply combinations of the signals from the individual bases that comprise the sequence, SERS spectra of unmodified ss-DNA sequences were obtained using a hydroxylamine-reduced Ag colloid aggregated with MgSO4. Initially, synthetic oligodeoxynucleotides with systematic structural variations were used to investigate the effect of adding single nucleobases to the 3' terminus of 10-mer and 20-mer sequences. It was found that the resulting SERS difference spectra could be used to identify the added nucleobases since they closely matched reference spectra of the same nucleobase. Investigation of the variation in intensity of an adenine probe which was moved along a test sequence showed there was a small end effect where nucleobases near the 3' terminus gave slightly larger signals but the effect was minor (30%). More significantly, in a sample set comprising 25-mer sequences where A, T or G nucleobases were substituted either near the centres of the sequences or the 5' or 3' ends, the SERS difference spectra only matched the expected form in approximately half the cases tested. This variation appeared to be due to changes in secondary structure induced by altering the sequences since uncoiling the sequences in a thermal pre-treatment step gave difference spectra which in all cases matched the expected form. Multivariate analysis of the set of substitution data showed that 99% of the variance could be accounted for in a model with just three factors whose loadings matched the spectra of the A, T, and G nucleobases and which contained no positional information. This suggests that aside from the differences in secondary structure which can be eliminated by thermal pre-treatment, the SERS spectra of the 25-mers studied here are simply the sum of their component parts. Although this means that SERS provides very little information on the primary sequence it should be excellent for the detection of post

  15. Aptamer-Based Single-Step Assay by the Fluorescence Enhancement on Electroless Plated Nano Au Substrate.

    PubMed

    Nambi Krishnan, Jegatha; Park, Sang-Hwi; Kim, Sang Kyung

    2017-09-07

    A new single-step aptamer-based surface-enhanced fluorescent optical sensor is built, by combining an aptamer-target interaction for target recognition and a fluorophore interaction for signal enhancement. The developed aptasensor is simple, sensitive, specific and stable for the detection of thrombin. A new nanometallic Au structure in the range of 100 nm was constructed through effective electroless plating method on a Cu thin film. Cu⁺ ions act as sacrificial seeds for the reduction of Au(2+/3+) ions to form Au nanolawns. In order to utilize the structure for a fluorescence-based sensor, aptamer conjugated with Cy3 was immobilized on the nanogold substrate through electrostatic attraction. The Au substrate was coated with chitosan (molecular weight 1000 Da). Thrombin binding aptamer (TBA) was applied as a model system demonstrating the aptamer-based fluorescence assay on nanogold substrates. Thrice-enhanced fluorescence emission was achieved with Cy3-conjugated TBA stably immobilized on the chitosan-coated Au substrate. The intensity change was proportional to the concentration of thrombin from 10 μM to 10 pM, whereas the intensity change was ignorable for other proteins such as human serum albumin (HSA). Aptamer-based assay benefited from simple immobilization of receptors and Au nanostructure contributed in building an effective surface enhancing/positively charged substrate was proved. Such an aptasensor holding high utilities for point-of-care devices by incorporating simplicity, sensitivity and selectivity in detection, low-cost for test, small sample volumes has been developed.

  16. 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.

  17. 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.

  18. Enhanced vasculotoxic metal excretion in post-myocardial infarction patients following a single edetate disodium-based infusion.

    PubMed

    Arenas, Ivan A; Navas-Acien, Ana; Ergui, Ian; Lamas, Gervasio A

    2017-10-01

    Toxic metals have been associated with cardiovascular mortality and morbidity. We have hypothesized that enhanced excretion of vasculotoxic metals might explain the positive results of the Trial to Assess Chelation Therapy (TACT). The purpose of this study was to determine whether a single infusion of the edetate disodium- based infusion used in TACT led to enhanced excretion of toxic metals known to be associated with cardiovascular events. Twenty six patients (post-MI, age > 50 years, serum creatinine ≤ 2.0mg/dL) were enrolled in this open-label study. Urinary levels of 20 toxic metals normalized to urinary creatinine concentrations were measured at baseline in overnight urine collections, for 6h following a placebo infusion of 500mL normal saline and 1.2% dextrose, and for 6h following a 3g edetate disodium-based infusion. Self-reported metal exposure, smoking status, food frequency, occupational history, drinking water source, housing and hobbies were collected at baseline by a metal exposure questionnaire. The mean age was 65 years (range 51-81 years). All patients were male. 50% had diabetes mellitus and 58% were former smokers. Mean (SD) serum creatinine was 0.95 (0.31) mg/dL. Toxic metals were detected in the baseline urine of >80% of patients. After placebo infusion there were no significant changes in total urinary metal levels. After edetate infusion, total urinary metal level increased by 71% compared to baseline (1500 vs. 2580µg/g creatinine; P<0.0001). The effect of edetate was particularly large for lead (3835% increase) and cadmium (633% increase). Edetate disodium-based infusions markedly enhanced the urinary excretion of lead and cadmium, toxic metals with established epidemiologic evidence and mechanisms linking them to coronary and vascular events. Copyright © 2017 Elsevier Inc. All rights reserved.

  19. Neurofeedback-Based Enhancement of Single Trial Auditory Evoked Potentials: Feasibility in Healthy Subjects.

    PubMed

    Rieger, Kathryn; Rarra, Marie-Helene; Moor, Nicolas; Diaz Hernandez, Laura; Baenninger, Anja; Razavi, Nadja; Dierks, Thomas; Hubl, Daniela; Koenig, Thomas

    2017-05-01

    Previous studies showed a global reduction of the event-related potential component N100 in patients with schizophrenia, a phenomenon that is even more pronounced during auditory verbal hallucinations. This reduction assumingly results from dysfunctional activation of the primary auditory cortex by inner speech, which reduces its responsiveness to external stimuli. With this study, we tested the feasibility of enhancing the responsiveness of the primary auditory cortex to external stimuli with an upregulation of the event-related potential component N100 in healthy control subjects. A total of 15 healthy subjects performed 8 double-sessions of EEG-neurofeedback training over 2 weeks. The results of the used linear mixed effect model showed a significant active learning effect within sessions ( t = 5.99, P < .001) against an unspecific habituation effect that lowered the N100 amplitude over time. Across sessions, a significant increase in the passive condition ( t = 2.42, P = .03), named as carry-over effect, was observed. Given that the carry-over effect is one of the ultimate aims of neurofeedback, it seems reasonable to apply this neurofeedback training protocol to influence the N100 amplitude in patients with schizophrenia. This intervention could provide an alternative treatment option for auditory verbal hallucinations in these patients.

  20. Structure-based Molecular Simulations Reveal the Enhancement of Biased Brownian Motions in Single-headed Kinesin

    PubMed Central

    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.” PMID:23459019

  1. Multiple enhanced self-protected spanning trees based architecture for recovery from single failure in metro ethernet

    NASA Astrophysics Data System (ADS)

    Li, Yong; Chen, Wentao; Jin, Depeng; Su, Li; Zeng, Lieguang

    2008-11-01

    Carriers and service providers are rushing to provide Ethernet-based virtual private network services in metro area network (MAN) as the most cost effective way to address the needs of the enterprise network market. To address the fast recovery from any signal failure issue in the Metro Ethernet, we propose a metro Ethernet architecture based on multiple Enhanced Self-protected Spanning Trees (ESST). The recovery mechanism, named Birthday-based Link Replacing Mechanism (BLRM), in this architecture is able to transform a self-protected spanning tree into another spanning tree after any signal link or node failure. Simulation result demonstrates the effectiveness of the BLRM in achieving fast recovery.

  2. 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

  3. 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.

  4. Gold-nanopatterned single interleukin-6 sandwich immunoassay chips with zeptomolar detection capability based on evanescent field-enhanced fluorescence imaging.

    PubMed

    Lee, Seungah; Kang, Seong Ho

    2013-06-21

    We developed a gold-nanopatterned immunoassay chip for single-molecule detection of interleukin-6 based on evanescent field-enhanced fluorescence imaging. The detection limit (496 zM) means that only four molecules need to be present per spot for detection. The sensitivity of this chip is ~5.4 × 10(4)-fold greater than that of a commercial ELISA for IL-6.

  5. Enhanced ultraviolet-visible light responses of phototransistors based on single and a few ZrS₃ nanobelts.

    PubMed

    Tao, You-Rong; Wu, Jia-Jing; Wu, Xing-Cai

    2015-09-14

    Phototransistors based on single and three ZrS3 nanobelts were fabricated on SiO2/Si wafers by photolithography and the lift-off technique, respectively, and their light-induced electric properties were investigated in detail. Both the devices demonstrate a remarkable photoresponse from ultraviolet to near infrared light. The photoswitch current ratio (PCR) of the single-nanobelt phototransistor is 13 under the illumination of 405 nm light with an optical power of 10.5 mW cm(-2) at a bias of 5 V, while the PCR of the three-nanobelt device is 210 under the illumination of 405 nm light with an optical power of 5.57 mW cm(-2) at a bias of 1 V. On comparison of the photoresponses under the same conditions, the latter is found to be superior to the former, and both the devices show a much better photoresponse than the reported flexible ZrS3-nanobelt-film photodetector.

  6. Sensitivity enhancement of graphene/zinc oxide nanocomposite-based electrochemical impedance genosensor for single stranded RNA detection.

    PubMed

    Low, Sze Shin; Loh, Hwei-San; Boey, Jian Sheng; Khiew, Poi Sim; Chiu, Wee Siong; Tan, Michelle T T

    2017-08-15

    An efficient electrochemical impedance genosensing platform has been constructed based on graphene/zinc oxide nanocomposite produced via a facile and green approach. Highly pristine graphene was synthesised from graphite through liquid phase sonication and then mixed with zinc acetate hexahydrate for the synthesis of graphene/zinc oxide nanocomposite by solvothermal growth. The as-synthesised graphene/zinc oxide nanocomposite was characterised with scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy and X-ray diffractometry (XRD) to evaluate its morphology, crystallinity, composition and purity. An amino-modified single stranded DNA oligonucleotide probe synthesised based on complementary Coconut Cadang-Cadang Viroid (CCCVd) RNA sequence, was covalently bonded onto the surface of graphene/zinc oxide nanocomposite by the bio-linker 1-pyrenebutyric acid N-hydroxysuccinimide ester. The hybridisation events were monitored by electrochemical impedance spectroscopy (EIS). Under optimised sensing conditions, the single stranded CCCVd RNA oligonucleotide target could be quantified in a wide range of 1.0×10(-11)M to 1.0×10(-6) with good linearity (R =0.9927), high sensitivity with low detection limit of 4.3×10(-12)M. Differential pulse voltammetry (DPV) was also performed for the estimation of nucleic acid density on the graphene/zinc oxide nanocomposite-modified sensing platform. The current work demonstrates an important advancement towards the development of a sensitive detection assay for various diseases involving RNA agents such as CCCVd in the future. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. On the enhancement of training session performance via attention for single-frequency/multi-commands based steady state auditory evoked potential BCI.

    PubMed

    Punsawad, Yunyong; Wongsawat, Yodchanan

    2012-01-01

    To solve the eye fatigue problem on using the well known steady state visual evoked potential (SSVEP)-based brain-computer interface (BCI) system, the steady state auditory evoked potential (SSAEP) becomes one of the promising BCI modalities. However, SSAEP-based BCI system still suffers from the low accuracy. To increase the accuracy, in this paper, we propose the new training method to enhance the SSAEP training session. The training process is enhanced by making the users control their attention levels simultaneously with the detected auditory stimulus frequency. Furthermore, with the proposed training method, we also propose the corresponding single-frequency/multi-commands BCI paradigm. With the proposed paradigm, four commands can be detected by using only one auditory stimulus frequency. The proposed training system yields approximately 81% accuracy compared with 66% of the session without performing the proposed training.

  8. Can template-based protein models guide the design of sequence fitness for enhanced thermal stability of single domain antibodies?

    PubMed

    Olson, Mark A; Zabetakis, Dan; Legler, Patricia M; Turner, Kendrick B; Anderson, George P; Goldman, Ellen R

    2015-10-01

    We investigate the practical use of comparative (template-based) protein models in replica-exchange simulations of single-domain antibody (sdAb) chains to evaluate if the models can correctly predict in rank order the thermal susceptibility to unfold relative to experimental melting temperatures. The baseline model system is the recently determined crystallographic structure of a llama sdAb (denoted as A3), which exhibits an unusually high thermal stability. An evaluation of the simulation results for the A3 comparative model and crystal structure shows that, despite the overall low Cα root-mean-square deviation between the two structures, the model contains misfolded regions that yields a thermal profile of unraveling at a lower temperature. Yet comparison of the simulations of four different comparative models for sdAb A3, C8, A3C8 and E9, where A3C8 is a design of swapping the sequence of the complementarity determining regions of C8 onto the A3 framework, discriminated among the sequences to detect the highest and lowest experimental melting transition temperatures. Further structural analysis of A3 for selected alanine substitutions by a combined computational and experimental study found unexpectedly that the comparative model performed admirably in recognizing substitution 'hot spots' when using a support-vector machine algorithm.

  9. Double-diffusion-based synthesis of BiVO4 mesoporous single crystals with enhanced photocatalytic activity for oxygen evolution.

    PubMed

    Wu, Qiangfang; Bao, Shenyuan; Tian, Baozhu; Xiao, Yifei; Zhang, Jinlong

    2016-06-14

    BiVO4 mesoporous single crystals (MSCs) were successfully prepared, for the first time, by a one-step hydrothermal method using the acidified BiVO4 precursor solution pre-impregnated silica as the template. It was revealed that the BiVO4 MSCs were formed by a double-diffusion mechanism. The O2 evolution rate over BiVO4 MSCs was improved nearly 10 times than that over BiVO4 bulk single crystals.

  10. 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.

  11. Using surface-enhanced Raman spectroscopy and electrochemically driven melting to discriminate Yersinia pestis from Y. pseudotuberculosis based on single nucleotide polymorphisms within unpurified polymerase chain reaction amplicons.

    PubMed

    Papadopoulou, Evanthia; Goodchild, Sarah A; Cleary, David W; Weller, Simon A; Gale, Nittaya; Stubberfield, Michael R; Brown, Tom; Bartlett, Philip N

    2015-02-03

    The development of sensors for the detection of pathogen-specific DNA, including relevant species/strain level discrimination, is critical in molecular diagnostics with major impacts in areas such as bioterrorism and food safety. Herein, we use electrochemically driven denaturation assays monitored by surface-enhanced Raman spectroscopy (SERS) to target single nucleotide polymorphisms (SNPs) that distinguish DNA amplicons generated from Yersinia pestis, the causative agent of plague, from the closely related species Y. pseudotuberculosis. Two assays targeting SNPs within the groEL and metH genes of these two species have been successfully designed. Polymerase chain reaction (PCR) was used to produce Texas Red labeled single-stranded DNA (ssDNA) amplicons of 262 and 251 bases for the groEL and metH targets, respectively. These amplicons were used in an unpurified form to hybridize to immobilized probes then subjected to electrochemically driven melting. In all cases electrochemically driven melting was able to discriminate between fully homologous DNA and that containing SNPs. The metH assay was particularly challenging due to the presence of only a single base mismatch in the middle of the 251 base long PCR amplicon. However, manipulation of assay conditions (conducting the electrochemical experiments at 10 °C) resulted in greater discrimination between the complementary and mismatched DNA. Replicate data were collected and analyzed for each duplex on different days, using different batches of PCR product and different sphere segment void (SSV) substrates. Despite the variability introduced by these differences, the assays are shown to be reliable and robust providing a new platform for strain discrimination using unpurified PCR samples.

  12. 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.

  13. 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).

  14. Enhancing Problem-Based Learning Designs with a Single E-Learning Scaffolding Tool: Two Case Studies Using Challenge FRAP

    ERIC Educational Resources Information Center

    Stewart, Terry M.; MacIntyre, William R.; Galea, Victor J.; Steel, Caroline H.

    2007-01-01

    Problem-based learning (PBL) is a powerful instructional approach. By working through assessable complex problem-solving tasks learners can be encouraged to actively engage in investigation and inquiry and to use high level cognitive thought processes to solve real-life problems in professional contexts. A critical element of a successful PBL…

  15. Enhancing Problem-Based Learning Designs with a Single E-Learning Scaffolding Tool: Two Case Studies Using Challenge FRAP

    ERIC Educational Resources Information Center

    Stewart, Terry M.; MacIntyre, William R.; Galea, Victor J.; Steel, Caroline H.

    2007-01-01

    Problem-based learning (PBL) is a powerful instructional approach. By working through assessable complex problem-solving tasks learners can be encouraged to actively engage in investigation and inquiry and to use high level cognitive thought processes to solve real-life problems in professional contexts. A critical element of a successful PBL…

  16. 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.

  17. Enhancement of Ag-Based Plasmonic Photocatalysis in Hydrogen Production from Ammonia Borane by the Assistance of Single-Site Ti-Oxide Moieties within a Silica Framework.

    PubMed

    Verma, Priyanka; Kuwahara, Yasutaka; Mori, Kohsuke; Yamashita, Hiromi

    2017-03-13

    Ag nanoparticles (NPs) have gained great attention owing to their interesting plasmonic properties and efficient catalysis under visible-light irradiation. In this study, an Ag-based plasmonic catalyst supported on mesoporous silica with isolated and tetrahedrally coordinated single-site Ti-oxide moieties, namely, Ag/Ti-SBA-15, was designed with the purpose of utilizing the broad spectral range of solar energy. The Ti-SBA-15 support allows the deposition of small Ag NPs with a narrow size distribution. The chemical structure, morphology, and optical properties of the prepared catalyst were characterized by techniques such as UV/Vis, FT extended X-ray absorption fine structure, and X-ray photoelectron spectroscopy, field-emission SEM, TEM, and N2 physisorption studies. The catalytic activity of Ag/Ti-SBA-15 in hydrogen production from ammonia borane by hydrolysis was significantly enhanced in comparison with Ag/SBA-15 without Ti-oxide moieties and Ag/TiO2 /SBA-15 involving agglomerated TiO2 , both in the dark and under light irradiation. Improved electron transfer under light irradiation caused by the creation of heterojunctions between Ag NPs and Ti-oxide moieties explains the results obtained in the present study.

  18. Non-contrast-enhanced MR angiography in critical limb ischemia: performance of quiescent-interval single-shot (QISS) and TSE-based subtraction techniques.

    PubMed

    Altaha, Mustafa A; Jaskolka, Jeffrey D; Tan, Kongteng; Rick, Manuela; Schmitt, Peter; Menezes, Ravi J; Wintersperger, Bernd J

    2017-03-01

    The aim of this study was to evaluate diagnostic performance of non-contrast-enhanced 2D quiescent-interval single-shot (QISS) and 3D turbo spin-echo (TSE)-based subtraction magnetic resonance angiography (MRA) in the assessment of peripheral arteries in patients with critical limb ischemia (CLI). Nineteen consecutive patients (74 % male, 72.8 ± 9.9 years) with CLI underwent 2D QISS and 3D TSE-based subtraction MRA at 1.5 T. Axial-overlapping QISS MRA (3 mm/2 mm; 1 × 1 mm(2)) covered from the toes to the aortic bifurcation while coronal 3D TSE-based subtraction MRA (1.3 × 1.2 × 1.3 mm(3)) was restricted to the calf only. MRA data sets (two readers) were evaluated for stenosis (≥50 %) and image quality. Results were compared with digital subtraction angiography (DSA). Two hundred and sixty-seven (267) segments were available for MRA-DSA comparison, with a prevalence of stenosis ≥50 % of 41.9 %. QISS MRA was rated as good to excellent in 79.5-96.0 % of segments without any nondiagnostic segments; 89.8-96.1 % of segments in 3D TSE-based subtraction MRA were rated as nondiagnostic or poor. QISS MRA sensitivities and specificities (segmental) were 92 % and 95 %, respectively, for reader one and 81-97 % for reader two. Due to poor image quality of 3D TSE-based subtraction MRA, diagnostic performance measures were not calculated. QISS MRA demonstrates excellent diagnostic performance and higher robustness than 3D TSE-based subtraction MRA in the challenging patient population with CLI. • QISS MRA allows reliable diagnosis of peripheral artery stenosis in critical limb ischemia. • Robustness of TSE-based subtraction MRA is limited in critical limb ischemia. • QISS MRA allows robust therapy planning in PAD patients with resting leg pain.

  19. 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

  20. Surface enhanced raman spectroscopy studies on triglycine sulphate single crystals

    NASA Astrophysics Data System (ADS)

    Parameswari, A.; Mohamed Asath, R.; Premkumar, R.; Milton Franklin Benial, A.

    2017-01-01

    Adsorption characteristics of triglycine sulphate (TGS) on silver (Ag) surface were investigated based on density functional theory calculations and surface enhanced Raman spectroscopy (SERS) technique. The single crystals of TGS were grown by slow evaporation method. Ag nanoparticles (Ag NPs) were prepared by solution combustion method and characterized. The calculated and observed structural parameters of TGS molecule were compared. Raman and SERS spectra for TGS single crystal were studied experimentally and validated theoretically. Frontier molecular orbitals (FMOs) analysis was carried out for TGS and TGS adsorbed on Ag surface. The second harmonic generation measurements confirm the nonlinear optical (NLO) activity of the TGS molecule. SERS spectral analysis reveals that the TGS adsorbed as tilted orientation on the silver surface. The theoretical and experimental results evidence the suitability of the grown TGS single crystal for optoelectronic applications.

  1. 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.

  2. Vacuum ultraviolet lamp based magnetic field enhanced photoelectron ionization and single photon ionization source for online time-of-flight mass spectrometry.

    PubMed

    Wu, Qinghao; Hua, Lei; Hou, Keyong; Cui, Huapeng; Chen, Wendong; Chen, Ping; Wang, Weiguo; Li, Jinghua; Li, Haiyang

    2011-12-01

    A magnetic field enhanced photoelectron ionization (MEPEI) source combined with single photon ionization (SPI) was developed for an orthogonal acceleration time-of-flight mass spectrometer (oaTOFMS). A commercial radio frequency (rf) powered vacuum ultraviolet (VUV) lamp was used as SPI light source, and the photoelectrons generated by photoelectric effect were accelerated to induce electron ionization (EI). The MEPEI was obtained by applying a magnetic field of about 800 G with a permanent annular magnet. Compared to a nonmagnetic field photoelectron ionization source, the signal intensities for SO(2), SF(6), O(2), and N(2) in MEPEI were improved more than 2 orders with the photoelectron energy around 20 eV, while most of the characteristics of soft ionization still remained. Simulation with SIMION showed that the sensitivity enhancement in MEPEI was ascribed to the increase of the electron moving path and the improvement of the electrons transmission. The limits of detection for SO(2) and benzene were 750 and 80 ppbv within a detection time of 4 s, respectively. The advantages of the source, including broad range of ionizable compounds, reduced fragments, and good sensitivity with low energy MEPEI, were demonstrated by monitoring pyrolysis products of polyvinyl chloride (PVC) and the intermediate products in discharging of the SF(6) gas inpurity.

  3. Single-site surface-enhanced Raman scattering beyond spectroscopy

    NASA Astrophysics Data System (ADS)

    Takase, Mai; Yasuda, Satoshi; Murakoshi, Kei

    2016-04-01

    Recent progress in the observation of surface-enhanced Raman scattering (SERS) is reviewed to examine the possibility of finding a novel route for the effective photoexcitation of materials. The importance of well-controlled SERS experiments on a single molecule at a single site is discussed based on the difference in the information obtained from ensemble SERS measurements using multiple active sites with an uncontrolled number of molecules. A single-molecule SERS observation performed at a mechanically controllable breaking junction with a simultaneous conductivity measurement provides clear evidence of the drastic changes both in the intensity and in the Raman mode selectivity of the electromagnetic field generated by localized surface plasmon resonance. Careful control of the field at a few-nanometer-wide gap of a metal nanodimer results in the modification of the selection rule of electronic excitation of an isolated single-walled carbon nanotube. The examples shown in this review suggest that a single-site SERS observation could be used as a novel tool to find, develop, and implement applications of plasmon-induced photoexcitation of materials.

  4. 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.

  5. 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.

  6. Enhancing single-molecule fluorescence with nanophotonics.

    PubMed

    Acuna, Guillermo; Grohmann, Dina; Tinnefeld, Philip

    2014-10-01

    Single-molecule fluorescence spectroscopy has become an important research tool in the life sciences but a number of limitations hinder the widespread use as a standard technique. The limited dynamic concentration range is one of the major hurdles. Recent developments in the nanophotonic field promise to alleviate these restrictions to an extent that even low affinity biomolecular interactions can be studied. After motivating the need for nanophotonics we introduce the basic concepts of nanophotonic devices such as zero mode waveguides and nanoantennas. We highlight current applications and the future potential of nanophotonic approaches when combined with biological systems and single-molecule spectroscopy.

  7. 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.

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

    PubMed

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

    2012-05-01

    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.

  9. Single-material multilayer with enhanced photoactivity

    SciTech Connect

    Beydaghyan, Gisia; Boudreau, Mathieu; Riordon, Jason; Hache, Alain; Ashrit, P. V.

    2010-10-18

    Molybdenum trioxide (MoO{sub 3}) patterned at the nanometer scale is combined with the same material in its bulk form to produce Bragg mirrors with enhanced photoactive properties. MoO{sub 3} undergoes coloration with exposure to UV light but a multilayer structure which alternates between nanostructured and bulk MoO{sub 3} is 2.5 times more effective. Measurements with various multilayer arrangements suggest the proximity of bulk and nanostructured MoO{sub 3} favors the photoreaction with structural water. A possible minor contribution from electronic band shifting is also discussed.

  10. Substrate catalysis enhances single-enzyme diffusion.

    PubMed

    Muddana, Hari S; Sengupta, Samudra; Mallouk, Thomas E; Sen, Ayusman; Butler, Peter J

    2010-02-24

    We show that diffusion of single urease enzyme molecules increases in the presence of urea in a concentration-dependent manner and calculate the force responsible for this increase. Urease diffusion measured using fluorescence correlation spectroscopy increased by 16-28% over buffer controls at urea concentrations ranging from 0.001 to 1 M. This increase was significantly attenuated when urease was inhibited with pyrocatechol, demonstrating that the increase in diffusion was the result of enzyme catalysis of urea. Local molecular pH changes as measured using the pH-dependent fluorescence lifetime of SNARF-1 conjugated to urease were not sufficient to explain the increase in diffusion. Thus, a force generated by self-electrophoresis remains the most plausible explanation. This force, evaluated using Brownian dynamics simulations, was 12 pN per reaction turnover. These measurements demonstrate force generation by a single enzyme molecule and lay the foundation for a further understanding of biological force generation and the development of enzyme-driven nanomotors.

  11. Enhanced magnetochiral effects at microwave frequencies by a single metamolecule

    NASA Astrophysics Data System (ADS)

    Tomita, Satoshi; Kurosawa, Hiroyuki; Sawada, Kei; Ueda, Tetsuya

    2017-02-01

    We have experimentally and numerically studied the directional birefringence of X -band microwaves by magnetochiral (MCh) effects of a single metamolecule under dc magnetic fields at room temperature. Phase and amplitude transmission coefficients from top and bottom, i.e., S parameters of S21 and S12, are measured for the single metamolecule consisting of a copper chiral structure and ferrite cylinder in a waveguide. By applying a dc magnetic field, we observe a difference between S21 and S12, which is an emergence of the MCh effects with simultaneous space-inversion and time-reversal symmetry breaking. Numerical calculation based on a finite element method reproduces well the experimental results of the MCh effects. The MCh effect can be enhanced by using the magnetic resonance of the ferrite cylinder. Notably, numerical calculation predicts that the MCh effect is extremely enhanced by interacting magnetic resonance with a specific resonant structural optical activity, leading to a giant MCh effect. The giant MCh effect observed in the present study originates from the one-way transparency caused by the Fano resonance in the metamolecule.

  12. Strongly enhanced field-dependent single-molecule electroluminescence

    NASA Astrophysics Data System (ADS)

    Lee, Tae-Hee; Gonzalez, Jose I.; Dickson, Robert M.

    2002-08-01

    Individual, strongly electroluminescent Agn molecules (n = 28 atoms) have been electrically written within otherwise nonemissive silver oxide films. Exhibiting characteristic single-molecule behavior, these individual room-temperature molecules exhibit extreme electroluminescence enhancements (>104 vs. bulk and dc excitation on a per molecule basis) when excited with specific ac frequencies. Occurring through field extraction of electrons with subsequent reinjection and radiative recombination, single-molecule electroluminescence is enhanced by a general mechanism that avoids slow bulk material response. Thus, while we detail strong electroluminescence from single, highly fluorescent Agn molecules, this mechanism also yields strong ac-excited electroluminescence from similarly prepared, but otherwise nonemissive, individual Cu nanoclusters.

  13. Enhancing the mechanical properties of single-crystal CVD diamond.

    PubMed

    Liang, Qi; Yan, Chih-Shiue; Meng, Yufei; Lai, Joseph; Krasnicki, Szczesny; Mao, Ho-Kwang; Hemley, Russell J

    2009-09-09

    Approaches for enhancing the strength and toughness of single-crystal diamond produced by chemical vapor deposition (CVD) at high growth rates are described. CVD processes used to grow single-crystal diamond in high density plasmas were modified to incorporate boron and nitrogen. Semi-quantitative studies of mechanical properties were carried out using Vickers indentation techniques. The introduction of boron in single-crystal CVD diamond can significantly enhance the fracture toughness of this material without sacrificing its high hardness (∼78 GPa). Growth conditions were varied to investigate its effect on boron incorporation and optical properties by means of photoluminescence, infrared, and ultraviolet-visible absorption spectroscopy. Boron can be readily incorporated into single-crystal diamond by the methods used, but with nitrogen addition, the incorporation of boron was hindered. The spectroscopic measurements indicate that nitrogen and boron coexist in the diamond structure, which helps explain the origin of the enhanced fracture toughness of this material. Further, low pressure/high temperature annealing can enhance the intrinsic hardness of single-crystal CVD diamond by a factor of two without appreciable loss in fracture toughness. This doping and post-growth treatment of diamond may lead to new technological applications that require enhanced mechanical properties of diamond.

  14. Enhancing the Mechanical Properties of Single-Crystal CVD Diamond

    SciTech Connect

    Liang, Q.; Yan, C; Meng, Y; Lai, J; Krasnicki, S; Mao, H; Hemley, R

    2009-01-01

    Approaches for enhancing the strength and toughness of single-crystal diamond produced by chemical vapor deposition (CVD) at high growth rates are described. CVD processes used to grow single-crystal diamond in high density plasmas were modified to incorporate boron and nitrogen. Semi-quantitative studies of mechanical properties were carried out using Vickers indentation techniques. The introduction of boron in single-crystal CVD diamond can significantly enhance the fracture toughness of this material without sacrificing its high hardness ({approx}78 GPa). Growth conditions were varied to investigate its effect on boron incorporation and optical properties by means of photoluminescence, infrared, and ultraviolet-visible absorption spectroscopy. Boron can be readily incorporated into single-crystal diamond by the methods used, but with nitrogen addition, the incorporation of boron was hindered. The spectroscopic measurements indicate that nitrogen and boron coexist in the diamond structure, which helps explain the origin of the enhanced fracture toughness of this material. Further, low pressure/high temperature annealing can enhance the intrinsic hardness of single-crystal CVD diamond by a factor of two without appreciable loss in fracture toughness. This doping and post-growth treatment of diamond may lead to new technological applications that require enhanced mechanical properties of diamond.

  15. Single-shot adaptive measurement for quantum-enhanced metrology

    NASA Astrophysics Data System (ADS)

    Palittpongarnpim, Pantita; Wittek, Peter; Sanders, Barry C.

    2016-09-01

    Quantum-enhanced metrology aims to estimate an unknown parameter such that the precision scales better than the shot-noise bound. Single-shot adaptive quantum-enhanced metrology (AQEM) is a promising approach that uses feedback to tweak the quantum process according to previous measurement outcomes. Techniques and formalism for the adaptive case are quite different from the usual non-adaptive quantum metrology approach due to the causal relationship between measurements and outcomes. We construct a formal framework for AQEM by modeling the procedure as a decision-making process, and we derive the imprecision and the Craḿer- Rao lower bound with explicit dependence on the feedback policy. We also explain the reinforcement learning approach for generating quantum control policies, which is adopted due to the optimal policy being non-trivial to devise. Applying a learning algorithm based on differential evolution enables us to attain imprecision for adaptive interferometric phase estimation, which turns out to be SQL when non-entangled particles are used in the scheme.

  16. Alignment enhanced photoconductivity in single wall carbon nanotube films.

    PubMed

    Liu, Ye; Lu, Shaoxin; Panchapakesan, Balaji

    2009-01-21

    In this paper we report, for the first time, the alignment enhanced photoconductivity of single wall carbon nanotube films upon laser illumination. The photoconductivity exhibited an increase, decrease or even 'negative' values when the laser spot was on different positions between contact electrodes, showing a 'position' dependent photoconductivity of partially aligned films of carbon nanotubes. Photon induced charge carrier generation in single wall carbon nanotubes and subsequent charge separation across the metal-carbon nanotube contacts is believed to cause the photoconductivity changes. A net photovoltage of approximately 4 mV and a photocurrent of approximately 10 microA were produced under the laser intensity of approximately 273 mW with a quantum efficiency of approximately 7.8% in vacuum. The photocurrent was observed to be in the direction of nanotube alignment. Finally, there was a strong dependence of the polarization of the incident light on the photocurrent and the orientation of the films influenced the dynamics of the rise and fall of the photocurrent. All of these phenomena clearly have significance in the area of design and fabrication of solar cells, micro-opto-mechanical systems and photodetectors based on carbon nanotubes.

  17. Photoluminescence enhancement of the single InAs quantum dots through plasmonic Au island films

    SciTech Connect

    Wang, H. Y.; Dou, X. M.; Yang, Sh.; Su, D.; Jiang, D. S.; Ni, H. Q.; Niu, Z. C.; Sun, B. Q.

    2014-03-28

    The approach of optical positioning the single InAs quantum dots (QDs) was used for investigating QD photoluminescence (PL) enhancement based on plasmonic effect of nanometer-sized Au island films. It is found that the maximum increase of QD PL intensity is about thirty-eight fold after 5-nm thick Au island films are evaporated on the QD sample surface. The enhanced localized excitation field and increased QD radiative decay rate are responsible for this PL enhancement. This provides an alternative way of preparing bright single photon sources based on the plasmonic effect.

  18. 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.

  19. Nanoantenna Enhancement for Telecom-Wavelength Superconducting Single Photon Detectors

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

    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 nm 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.

  20. 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.

  1. The potential of virtual reality-based training to enhance the functional autonomy of Alzheimer's disease patients in cooking activities: A single case study.

    PubMed

    Foloppe, Déborah A; Richard, Paul; Yamaguchi, Takehiko; Etcharry-Bouyx, Frédérique; Allain, Philippe

    2015-10-20

    Impairments in performing activities of daily living occur early in the course of Alzheimer's disease (AD). There is a great need to develop non-pharmacological therapeutic interventions likely to reduce dependency in everyday activities in AD patients. This study investigated whether it was possible to increase autonomy in these patients in cooking activities using interventions based on errorless learning, vanishing-cue, and virtual reality techniques. We recruited a 79-year-old woman who met NINCDS-ADRDA criteria for probable AD. She was trained in four cooking tasks for four days per task, one hour per day, in virtual and in real conditions. Outcome measures included subjective data concerning the therapeutic intervention and the experience of virtual reality, repeated assessments of training activities, neuropsychological scores, and self-esteem and quality of life measures. The results indicated that our patient could relearn some cooking activities using virtual reality techniques. Transfer to real life was also observed. Improvement of the task performance remained stable over time. This case report supports the value of a non-immersive virtual kitchen to help people with AD to relearn cooking activities.

  2. Enhancement of below gap transmission of InAs single crystal via suppression of native defects

    NASA Astrophysics Data System (ADS)

    Shen, Guiying; Zhao, Youwen; Dong, Zhiyuan; Liu, Jingming; Xie, Hui; Bai, Yongbiao; Chen, Xiaoyu

    2017-03-01

    As-grown and annealed undoped n type InAs single crystals have been studied by Hall effect measurement, infrared transmission (IR) spectroscopy, photoluminescence spectroscopy (PL) and glow discharge mass spectroscopy (GDMS). After annealing, below-gap infrared transmittance of the InAs single crystal increases significantly with the annihilation of a 0.383 eV PL peak related defect. Mechanism of the transmission enhancement and the attribution of the defect is discussed based on the experimental results.

  3. Novel single-tube agar-based test system for motility enhancement and immunocapture of Escherichia coli O157:H7 by H7 flagellar antigen-specific antibodies.

    PubMed

    Murinda, Shelton E; Nguyen, Lien T; Ivey, Susan J; Almeida, Raul A; Oliver, Stephen P

    2002-12-01

    This paper describes a novel single-tube agar-based technique for motility enhancement and immunoimmobilization of Escherichia coli O157:H7. Motility indole ornithine medium and agar (0.4%, wt/vol) media containing either nutrient broth, tryptone broth, or tryptic soy broth (TSBA) were evaluated for their abilities to enhance bacterial motility. Twenty-six E. coli strains, including 19 O157:H7 strains, 1 O157:H(-) strain, and 6 generic E. coli strains, were evaluated. Test bacteria were stab inoculated in the center of the agar column, and tubes were incubated at 37 degrees C for 18 to 96 h. Nineteen to 24 of the 26 test strains (73.1 to 92.3%) were motile in the different media. TSBA medium performed best and was employed in subsequent studies of motility enhancement and H7 flagellar immunocapture. H7 flagellar antiserum (30 and 60 micro l) mixed with TSBA was placed as a band (1 ml) in the middle of an agar column separating the top (3-ml) and bottom (3-ml) agar layers. The top agar layer was inoculated with the test bacterial strains. The tubes were incubated at 37 degrees C for 12 to 18 h and for 18 to 96 h. The specificity and sensitivity of the H7 flagellar immunocapture tests were 75 and 100%, respectively. The procedure described is simple and sensitive and could be adapted easily for routine use in laboratories that do not have sophisticated equipment and resources for confirming the presence of H7 flagellar antigens. Accurate and rapid identification of H7 flagellar antigen is critical for the complete characterization of E. coli O157:H7, owing to the immense clinical, public health, and economic significance of this food-borne pathogen.

  4. 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.

  5. 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

  6. Surface enhanced single-molecule magnetism involving 4f spin

    SciTech Connect

    Zhang, Yachao

    2016-03-28

    We study the magnetic anisotropy energy (MAE) of the isolated and deposited Eu(C{sub 8}H{sub 8}){sub 2} by first-principles calculations considering the van der Waals correction and the strong correlation effects. We find that both the molecular spin moment and the easy-axis magnetic anisotropy are enhanced upon deposition on Cu(111). We propose a mechanism in terms of the weakened spin polarization of the π-2p orbitals and the induced anisotropic occupations of the 4f orbitals. Our findings pave the way for raising the MAE of 4f-element single-molecule magnets by tailoring the molecule–surface contacts.

  7. Surface enhanced single-molecule magnetism involving 4f spin

    NASA Astrophysics Data System (ADS)

    Zhang, Yachao

    2016-03-01

    We study the magnetic anisotropy energy (MAE) of the isolated and deposited Eu(C8H8)2 by first-principles calculations considering the van der Waals correction and the strong correlation effects. We find that both the molecular spin moment and the easy-axis magnetic anisotropy are enhanced upon deposition on Cu(111). We propose a mechanism in terms of the weakened spin polarization of the π-2p orbitals and the induced anisotropic occupations of the 4f orbitals. Our findings pave the way for raising the MAE of 4f-element single-molecule magnets by tailoring the molecule-surface contacts.

  8. Force enhancement following stretch in a single sarcomere.

    PubMed

    Leonard, T R; DuVall, M; Herzog, W

    2010-12-01

    It has been accepted for half a century that, for a given level of activation, the steady-state isometric force of a muscle sarcomere depends exclusively on the amount of overlap between the contractile filaments actin and myosin, or equivalently sarcomere length (Gordon AM et al., J Physiol 184: 170-192, 1966). Moreover, according to the generally accepted paradigm of muscle contraction, the cross-bridge theory (Huxley AF, Prog Biophys Biophys Chem 7: 255-318, 1957), this steady-state isometric sarcomere force is independent of the muscle's contractile history (Huxley AF, Prog Biophys Biophys Chem 7: 255-318, 1957; Walcott S and Herzog W, Math Biosci 216: 172-186, 2008); i.e., it is independent of whether a muscle is held at a constant length before and during the contraction or whether the muscle is shortened or lengthened to the same constant length. This, however, is not the case, as muscles and single fibers that are stretched show greatly increased steady-state isometric forces compared with preparations that are held at a constant length (Abbott BC and Aubert XM, J Physiol 117: 77-86, 1952; De Ruiter CJ et al., J Physiol 526.3: 671-681, 2000; Edman KAP et al., J Physiol 281: 139-155, 1978; Edman KAP et al., J Gen Physiol 80: 769-784, 1982; Edman KAP and Tsuchiya T, J Physiol 490.1: 191-205, 1996). This so-called "residual force enhancement" (Edman KAP et al., J Gen Physiol 80: 769-784, 1982) offers a perplexing puzzle for muscle physiologists. Many theories have been advanced to address the discrepancy between prediction and observation with the most popular and accepted being the sarcomere length nonuniformity theory (Morgan DL, Biophys J 57: 209-221, 1990), which explains the residual force enhancement with the development of large nonuniformities in sarcomere lengths during muscle stretching. Here, we performed experiments in mechanically isolated sarcomeres and observed that the residual force enhancement following active stretching is preserved. Since

  9. 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.

  10. Polarization-controlled gap-mode surface-enhanced Raman scattering with a single nanoparticle

    NASA Astrophysics Data System (ADS)

    Dou, Xiujie; Yang, Aiping; Min, Changjun; Du, Luping; Zhang, Yuquan; Weng, Xiaoyu; Yuan, Xiaocong

    2017-06-01

    Metallic nanoparticle-film gaps are widely used as high-efficiency surface-enhanced Raman scattering (SERS) substrates owing to the plasmonic hybridization of the propagating surface plasmon polaritons on the films and the localized surface plasmons on the nanoparticles. Here, based on both theoretical and experimental studies, we reveal the enhancement mechanism of gap-mode SERS in a single nanoparticle-film gap by comparing the SERS intensity under different incident polarizations. The results demonstrate that the SERS signal can be significantly enhanced under illumination with radial polarization and can be significantly suppressed under azimuthal polarization (as compared with under traditional linear polarization). This is attributed to the distinct longitudinal electric field distributions of the excited surface plasmon polaritons. The results of our work will be of great interest for single-particle SERS research and quantitative molecular detection.

  11. Rapid ultrasensitive single particle surface-enhanced Raman spectroscopy using metallic nanopores.

    PubMed

    Cecchini, Michael P; Wiener, Aeneas; Turek, Vladimir A; Chon, Hyangh; Lee, Sangyeop; Ivanov, Aleksandar P; McComb, David W; Choo, Jaebum; Albrecht, Tim; Maier, Stefan A; Edel, Joshua B

    2013-10-09

    Nanopore sensors embedded within thin dielectric membranes have been gaining significant interest due to their single molecule sensitivity and compatibility of detecting a large range of analytes, from DNA and proteins, to small molecules and particles. Building on this concept we utilize a metallic Au solid-state membrane to translocate and rapidly detect single Au nanoparticles (NPs) functionalized with 589 dye molecules using surface-enhanced resonance Raman spectroscopy (SERRS). We show that, due to the plasmonic coupling between the Au metallic nanopore surface and the NP, signal intensities are enhanced when probing analyte molecules bound to the NP surface. Although not single molecule, this nanopore sensing scheme benefits from the ability of SERRS to provide rich vibrational information on the analyte, improving on current nanopore-based electrical and optical detection techniques. We show that the full vibrational spectrum of the analyte can be detected with ultrahigh spectral sensitivity and a rapid temporal resolution of 880 μs.

  12. 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.

  13. Single nanoparticle detection using photonic crystal enhanced microscopy.

    PubMed

    Zhuo, Yue; Hu, Huan; Chen, Weili; Lu, Meng; Tian, Limei; Yu, Hojeong; Long, Kenneth D; Chow, Edmond; King, William P; Singamaneni, Srikanth; Cunningham, Brian T

    2014-03-07

    We demonstrate a label-free biosensor imaging approach that utilizes a photonic crystal (PC) surface to detect surface attachment of individual dielectric and metal nanoparticles through measurement of localized shifts in the resonant wavelength and resonant reflection magnitude from the PC. Using a microscopy-based approach to scan the PC resonant reflection properties with 0.6 μm spatial resolution, we show that metal nanoparticles attached to the biosensor surface with strong absorption at the resonant wavelength induce a highly localized reduction in reflection efficiency and are able to be detected by modulation of the resonant wavelength. Experimental demonstrations of single-nanoparticle imaging are supported by finite-difference time-domain computer simulations. The ability to image surface-adsorption of individual nanoparticles offers a route to single molecule biosensing, in which the particles can be functionalized with specific recognition molecules and utilized as tags.

  14. Combination of MVDR beamforming and single-channel spectral processing for enhancing noisy and reverberant speech

    NASA Astrophysics Data System (ADS)

    Cauchi, Benjamin; Kodrasi, Ina; Rehr, Robert; Gerlach, Stephan; Jukić, Ante; Gerkmann, Timo; Doclo, Simon; Goetze, Stefan

    2015-12-01

    This paper presents a system aiming at joint dereverberation and noise reduction by applying a combination of a beamformer with a single-channel spectral enhancement scheme. First, a minimum variance distortionless response beamformer with an online estimated noise coherence matrix is used to suppress noise and reverberation. The output of this beamformer is then processed by a single-channel spectral enhancement scheme, based on statistical room acoustics, minimum statistics, and temporal cepstrum smoothing, to suppress residual noise and reverberation. The evaluation is conducted using the REVERB challenge corpus, designed to evaluate speech enhancement algorithms in the presence of both reverberation and noise. The proposed system is evaluated using instrumental speech quality measures, the performance of an automatic speech recognition system, and a subjective evaluation of the speech quality based on a MUSHRA test. The performance achieved by beamforming, single-channel spectral enhancement, and their combination are compared, and experimental results show that the proposed system is effective in suppressing both reverberation and noise while improving the speech quality. The achieved improvements are particularly significant in conditions with high reverberation times.

  15. Thermoelectric ZT enhanced by asymmetric configuration in single-molecule-magnet junctions

    NASA Astrophysics Data System (ADS)

    Niu, Pengbin; Shi, Yunlong; Sun, Zhu; Nie, Yi-Hang; Luo, Hong-Gang

    2016-02-01

    In mesoscopic devices, many factors like the Coulomb and spin interactions can enhance the thermoelectric figure of merit ZT. Here we use a system consisting of a single-molecule magnet (SMM) connected to two ferromagnetic electrodes to consider the possible enhancement effects of thermoelectric efficiency. By introducing an asymmetric configuration to the transport junction, we find that this configuration can significantly enhance the thermoelectric ZT. The optimized asymmetric thermoelectric ZT is five times that of the ZT with a symmetric configuration or non-magnetic case. Due to this asymmetry, a non-zero charge thermopower at the electron-hole symmetry point is also found. These results demonstrate that the asymmetry of the transport junction helps to enhance thermoelectric efficiency and is useful for fabricating SMM-based thermoelectric devices.

  16. Advanced piezoelectric single crystal based actuators

    NASA Astrophysics Data System (ADS)

    Jiang, Xiaoning; Rehrig, Paul W.; Hackenberger, Wesley S.; Smith, Edward; Dong, Shuxiang; Viehland, Dwight; Moore, Jim, Jr.; Patrick, Brian

    2005-05-01

    TRS is developing new actuators based on single crystal piezoelectric materials such as Pb(Zn1/3Nb2/3)1-xTixO3 (PZN-PT) and Pb(Mg1/3Nb2/3)x-1TixO3 (PMN-PT) which exhibit very high piezoelectric coefficients (d33 = 1800-2200 pC/N) and electromechanical coupling factors (k33 > 0.9), respectively, for a variety of applications, including active vibration damping, active flow control, high precision positioning, ultrasonic motors, deformable mirrors, and adaptive optics. The d32 cut crystal plate actuators showed d32 ~ -1600 pC/N, inter-digital electroded (IDE) plate actuators showed effective d33 ~ 1100 pC/N. Single crystal stack actuators with stroke of 10 μm-100 μm were developed and tested at both room temperature and cryogenic temperatures. Flextensional single crystal piezoelectric actuators with either stack driver or plate driver were developed with stroke 70 μm - > 250 μm. For large stroke cryogenic actuation (> 1mm), a single crystal piezomotor was developed and tested at temperature of 77 K-300K and stroke of > 10mm and step resolution of 20 nm were achieved. In order to demonstrate the significance of developed single crystal actuators, modeling on single crystal piezoelectric deformable mirrors and helicopter flap control using single crystal actuators were conducted and the modeling results show that more than 20 wavelength wavefront error could be corrected by using the single crystal deformable mirrors and +/- 5.8 ° flap deflection will be obtained for a 36" flap using single crystal stack actuators.

  17. Enhanced Thermoelectric Performance of Hybrid Nanoparticle-Single-Molecule Junctions

    NASA Astrophysics Data System (ADS)

    Zerah-Harush, Elinor; Dubi, Yonatan

    2015-06-01

    It was recently suggested that molecular junctions would be excellent elements for efficient and high-power thermoelectric energy-conversion devices. However, experimental measurements of thermoelectric conversion in molecular junctions indicate rather poor efficiency, raising the question of whether it is indeed possible to design a setup for molecular junctions that will exhibit enhanced thermoelectric performance. Here we suggest that hybrid single-molecule-nanoparticle junctions can serve as efficient thermoelectric converters. The introduction of a semiconducting nanoparticle introduces new tuning capabilities, which are absent in conventional metal-molecule-metal junctions. Using a generic model for the molecule and nanoparticle with realistic parameters, we demonstrate that the thermopower can be of the order of hundreds of microvolts per degree kelvin and that the thermoelectric figure of merit can reach values close to 1, an improvement of 4 orders of magnitude over existing measurements. This favorable performance persists over a wide range of experimentally relevant parameters and is robust against disorder (in the form of surface-attached molecules) and against electron decoherence at the nanoparticle-molecule interface.

  18. Spectral shapes of surface-enhanced resonance Raman scattering sensitive to the refractive index of media around single Ag nanoaggregates

    NASA Astrophysics Data System (ADS)

    Yoshida, Ken-ichi; Itoh, Tamitake; Biju, Vasudevanpillai; Ishikawa, Mitsuru; Ozaki, Yukihiro

    2009-12-01

    We found large spectral changes in surface-enhanced resonance Raman scattering (SERRS) with increasing refractive index of media around single Ag nanoaggregates. We analyzed relationship between the spectral changes in SERRS and those in plasma (plasmon) resonance based on the twofold electromagnetic (EM) enhancement theory. The analysis revealed that the changes in SERRS spectra are induced by changes in spectral shapes of twofold EM enhancement factors, which arise from coupling of plasma resonance with both incident and Raman scattering light.

  19. Rapid single-cell detection and identification of pathogens by using surface-enhanced Raman spectroscopy.

    PubMed

    Dina, N E; Zhou, H; Colniţă, A; Leopold, N; Szoke-Nagy, T; Coman, C; Haisch, C

    2017-05-21

    For the successful treatment of infections, real-time analysis and enhanced multiplex capacity, sensitivity and cost-effectiveness of the developed detection method are critical. In this work, surface-enhanced Raman scattering (SERS) was employed with the final aim of identification and discrimination of pathogenic bacteria, based on their detected SERS fingerprint at the single-cell level. Several genera of bacteria that are found in most of the isolated infections in bacteraemia were successfully identified in less than 5 minutes without the use of antibodies or other specific receptors. The key element of the SERS direct detection platform is the SERS substrate, which combines easy production at low costs with a high enhancement enabling single-cell detection. The innovative approach of detection required the in situ synthesis of silver nanoparticles (NPs), ensuring an intimate contact with the bacterial membrane. This protocol provided a good reproducibility of the single-cell SERS spectra and was successfully applied both on Gram-negative and Gram-positive microorganisms (E. coli, M. morganii, E. lactis, L. casei). Thus, a label-free SERS-based biosensor for pathogen detection was developed with low costs, minimal sample preparation, high-accuracy and a very short analysis time of less than 5 min, which is crucial for infection diagnosis.

  20. 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.

  1. Enhanced FMAM based on empirical kernel map.

    PubMed

    Wang, Min; Chen, Songcan

    2005-05-01

    The existing morphological auto-associative memory models based on the morphological operations, typically including morphological auto-associative memories (auto-MAM) proposed by Ritter et al. and our fuzzy morphological auto-associative memories (auto-FMAM), have many attractive advantages such as unlimited storage capacity, one-shot recall speed and good noise-tolerance to single erosive or dilative noise. However, they suffer from the extreme vulnerability to noise of mixing erosion and dilation, resulting in great degradation on recall performance. To overcome this shortcoming, we focus on FMAM and propose an enhanced FMAM (EFMAM) based on the empirical kernel map. Although it is simple, EFMAM can significantly improve the auto-FMAM with respect to the recognition accuracy under hybrid-noise and computational effort. Experiments conducted on the thumbnail-sized faces (28 x 23 and 14 x 11) scaled from the ORL database show the average accuracies of 92%, 90%, and 88% with 40 classes under 10%, 20%, and 30% randomly generated hybrid-noises, respectively, which are far higher than the auto-FMAM (67%, 46%, 31%) under the same noise levels.

  2. Direct synthesis of single-walled aminoaluminosilicate nanotubes with enhanced molecular adsorption selectivity

    NASA Astrophysics Data System (ADS)

    Kang, Dun-Yen; Brunelli, Nicholas A.; Yucelen, G. Ipek; Venkatasubramanian, Anandram; Zang, Ji; Leisen, Johannes; Hesketh, Peter J.; Jones, Christopher W.; Nair, Sankar

    2014-02-01

    Internal functionalization of single-walled nanotubes is an attractive, yet difficult challenge in nanotube materials chemistry. Here we report single-walled metal oxide nanotubes with covalently bonded primary amine moieties on their inner wall, synthesized through a one-step approach. Conclusive molecular-level structural information on the amine-functionalized nanotubes is obtained through multiple solid-state techniques. The amine-functionalized nanotubes maintain a high carbon dioxide adsorption capacity while significantly suppressing the adsorption of methane and nitrogen, thereby leading to a large enhancement in adsorption selectivity over unfunctionalized nanotubes (up to four-fold for carbon dioxide/methane and ten-fold for carbon dioxide/nitrogen). The successful synthesis of single-walled nanotubes with functional, covalently-bound organic moieties may open up possibilities for new nanotube-based applications that are currently inaccessible to carbon nanotubes and other related materials.

  3. Linearly enhanced response of thermopower in cascaded array of dual-stripe single-metal thermocouples

    NASA Astrophysics Data System (ADS)

    Li, Gang; Han, Danhong; Yang, Fan; Wang, Zhenhai; Pi, Yudan; Wang, Wei; Xu, Shengyong

    2017-05-01

    Based on the width dependence of thermopower, cascaded single-metal thermocouples were demonstrated in this report. The cascaded thermocouples were made from 100 nm thick Ni films with a 100 μm wide stripe and a 5 μm narrow stripe. The experiment results showed a linearly enhanced response of thermopower. The 64-cascaded thermocouple achieved an equivalent Seebeck coefficient of up to 55.69 μV/K, which is higher than that of a commercial type-K thermocouple (39.6 μV/K). The single-metal thermocouples were also fabricated on flexible substrates. With the simple fabrication process and remarkable temperature sensing ability, the cascaded single-metal thermocouples may find promising applications in temperature measurement of modern flexible electronic products and wearable devices.

  4. Single carrier frequency domain equalization based on SSB modulation

    NASA Astrophysics Data System (ADS)

    Zhang, Junwen; Fang, Wuliang; Shao, Yufeng; Huang, Bo; Chi, Nan

    2009-11-01

    Single-carrier frequency domain equalization (SC-FDE), as a mature technique in wireless commutation, is widely researched for signal equalization and compensation utilizing high speed electronic devices such as DSP. In this paper, for the first time, we propose and demonstrate a SC-FDE technique in optical communication system. By adopting SCFDE technique, after 50km, 80km, 100km transmission for a 10Gb/s ASK single sideband (SSB) signal on a single mode fiber (SMF), the dispersion of optical signa1 is effectively compensated. The SSB signal is generated by a dual-arm Mach-Zehnder modulator (MZM) cascading a phase modulator (PM) based on Hilbert Finite impulse response (FIR) digital filter. The results demonstrate, in our proposed SC-FDE model, the eye opening and the clock recovery is improved, and the effect of compensation is enhanced as the transmission distance increases.

  5. Polarised Raman spectroscopy on a single class of single-wall nanotubes by nano surface-enhanced scattering

    NASA Astrophysics Data System (ADS)

    Azoulay, J.; Débarre, A.; Richard, A.; Tchénio, P.; Bandow, S.; Iijima, S.

    2000-12-01

    We report on the opportunity of performing polarised Raman spectroscopy on nanotubes by using surface-enhanced Raman scattering (SERS) mechanisms at the scale of a single hot site. In conjunction with the opportunity of selecting a single class of single wall nanotubes (SWNTs), it opens the way to fine spectroscopic studies of carbon nanotubes. Results obtained on a single class of nanotubes demonstrate first that polarised Raman spectroscopy is possible when a single hot site of a SERS substrate is selected and second that in this situation, unambiguous assignment of the modes is possible.

  6. 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

    2015-12-09

    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.

  7. 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.

  8. 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.

  9. 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.

  10. Enhancement of single particle rare earth doped NaYF4: Yb, Er emission with a gold shell

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

    Upconversion of infrared light to visible light has important implications for bioimaging. However, the small absorption cross-section of rare earth dopants has limited the efficiency of these anti-Stokes nanomaterials. We present enhanced excitation absorption and single particle fluorescent emission of sodium yttrium fluoride, NaYF4: Yb, Er based upconverting nanoparticles coated with a gold nanoshell through surface plasmon resonance. The single gold-shell coated nanoparticles show enhanced absorption in the near infrared, enhanced total emission intensity, and increased green relative to red emission. We also show differences in enhancement between single and aggregated gold shell nanoparticles. The surface plasmon resonance of the gold-shell coated nanoparticle is shown to be dependent on the shell thickness. In contrast to other reported results, our single particle experimental observations are corroborated by finite element calculations that show where the green/red emission enhancement occurs, and what portion of the enhancement is due to electromagnetic effects. We find that the excitation enhancement and green/red emission ratio enhancement occurs at the corners and edges of the doped emissive core.

  11. Enhanced Catalysis Activity in a Coordinatively Unsaturated Cobalt-MOF Generated via Single-Crystal-to-Single-Crystal Dehydration.

    PubMed

    Ren, Hai-Yun; Yao, Ru-Xin; Zhang, Xian-Ming

    2015-07-06

    Hydrothermal reaction of Co(NO3)2 and terphenyl-3,2",5",3'-tetracarboxyate (H4tpta) generated Co3(OH)2 chains based 3D coordination framework Co3(OH)2(tpta)(H2O)4 (1) that suffered from single-crystal-to-single-crystal dehydration by heating at 160 °C and was transformed into dehydrated Co3(OH)2(tpta) (1a). During the dehydration course, the local coordination environment of part of the Co atoms was transformed from saturated octahedron to coordinatively unsaturated tetrahedron. Heterogenous catalytic experiments on allylic oxidation of cyclohexene show that dehydrated 1a has 6 times enhanced catalytic activity than as-synthesized 1 by using tert-butyl hydroperoxide (t-BuOOH) as oxidant. The activation energy for the oxidation of cylcohexene with 1a catalyst was 67.3 kJ/mol, far below the value with 1 catalysts, which clearly suggested that coordinatively unsaturated Co(II) sites in 1a have played a significant role in decreasing the activation energy. It is interestingly found that heterogeneous catalytic oxidation of cyclohexene in 1a not only gives the higher conversion of 73.6% but also shows very high selectivity toward 2-cyclohexene-1-one (ca. 64.9%), as evidenced in high turnover numbers (ca. 161) based on the open Co(II) sites of 1a catalyst. Further experiments with a radical trap indicate a radical chain mechanism. This work demonstrates that creativity of coordinatively unsaturated metal sites in MOFs could significantly enhance heterogeneous catalytic activity and selectivity.

  12. Enhanced Light Emitters Based on Metamaterials

    DTIC Science & Technology

    2015-03-30

    Enhanced Light Emitters based on Metamaterials We report the development of light emitters based on hyperbolic metamaterials . During the 18 month...layer, use of a high refractive index contrast grating to out-couple light from active hyperbolic metamaterials . We also successfully demonstrated for...the first time simultaneous enhancement in spontaneous emission ad light extraction from active metamaterial structures. The views, opinions and/or

  13. Short Peptides Enhance Single Cell Adhesion and Viability on Microarrays

    PubMed Central

    Veiseh, Mandana; Veiseh, Omid; Martin, Michael C.; Asphahani, Fareid; Zhang, Miqin

    2011-01-01

    Single cell patterning holds important implications for biology, biochemistry, biotechnology, medicine, and bioinformatics. The challenge for single cell patterning is to produce small islands hosting only single cells and retaining their viability for a prolonged period of time. This study demonstrated a surface engineering approach that uses a covalently-bound short peptide as a mediator to pattern cells with improved single cell adhesion and prolonged cellular viability on gold patterned SiO2 substrates. The underlying hypothesis is that cell adhesion is regulated by the type, availability and stability of effective cell adhesion peptides, and thus covalently bound short peptides would promote cell spreading and thus, single cell adhesion and viability. The effectiveness of this approach and the underlying mechanism for the increased probability of single cell adhesion and prolonged cell viability by short peptides were studied by comparing cellular behavior of human umbilical cord vein endothelial cells on three model surfaces whose gold electrodes were immobilized with fibronectin, physically adsorbed Arg-Glu-Asp-Val-Tyr, and covalently-bound Lys-Arg-Glu-Asp-Val-Tyr, respectively. The surface chemistry and binding properties were characterized by reflectance Fourier transform infrared spectroscopy. Both short peptides were superior to fibronectin in producing adhesion of only single cells, while the covalently bound peptide also reduced apoptosis and necrosis of adhered cells. Controlling cell spreading by peptide binding domains to regulate apoptosis and viability represents a fundamental mechanism in cell-materials interaction and provides an effective strategy in engineering arrays of single cells. PMID:17371055

  14. 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

  15. One-dimensional arrays of nanoshell dimers for single molecule spectroscopy via surface-enhanced Raman scattering.

    PubMed

    Zhao, Ke; Xu, Hongxing; Gu, Baohua; Zhang, Zhenyu

    2006-08-28

    The optical properties of one-dimensional arrays of metal nanoshell dimers are studied systematically using the T-matrix method based on Mie theory, within the context of surface enhanced Raman scattering (SERS). It is shown that the local electromagnetic enhancement can be as high as approximately 4.5 x 10(13) for nanoshell dimer arrays with optimal geometry, and sensitive tunability in the resonant frequency can be gained by varying the geometrical parameters, making such structures appealing templates for SERS measurements with single molecule sensitivity. The extraordinarily high enhancement is attributed to a collective photonic effect constructively superposed onto the intrinsic enhancement associated with an isolated nanoshell dimer.

  16. One-dimensional arrays of nanoshell dimers for single molecule spectroscopy via surface-enhanced raman scattering

    NASA Astrophysics Data System (ADS)

    Zhao, Ke; Xu, Hongxing; Gu, Baohua; Zhang, Zhenyu

    2006-08-01

    The optical properties of one-dimensional arrays of metal nanoshell dimers are studied systematically using the T-matrix method based on Mie theory, within the context of surface enhanced Raman scattering (SERS). It is shown that the local electromagnetic enhancement can be as high as ˜4.5×1013 for nanoshell dimer arrays with optimal geometry, and sensitive tunability in the resonant frequency can be gained by varying the geometrical parameters, making such structures appealing templates for SERS measurements with single molecule sensitivity. The extraordinarily high enhancement is attributed to a collective photonic effect constructively superposed onto the intrinsic enhancement associated with an isolated nanoshell dimer.

  17. First observation of enhanced luminescence from single lanthanide chelates on silver nanorods.

    PubMed

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

    2014-08-25

    We used near-field interactions with a silver nanorod (AgNR) to greatly enhance luminescence of a lanthanide (Ln) chelate. The enhancement factor was 280-fold, making single lanthanide luminescence detectable. This is also the first observation on single molecule detection (SMD) of a lanthanide dye.

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

    PubMed

    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.

  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 single-cell printing by acoustophoretic cell focusing

    PubMed Central

    Leibacher, I.; Schoendube, J.; Dual, J.; Zengerle, R.; Koltay, P.

    2015-01-01

    Recent years have witnessed a strong trend towards analysis of single-cells. To access and handle single-cells, many new tools are needed and have partly been developed. Here, we present an improved version of a single-cell printer which is able to deliver individual single cells and beads encapsulated in free-flying picoliter droplets at a single-bead efficiency of 96% and with a throughput of more than 10 beads per minute. By integration of acoustophoretic focusing, the cells could be focused in x and y direction. This way, the cells were lined-up in front of a 40 μm nozzle, where they were analyzed individually by an optical system prior to printing. In agreement with acoustic simulations, the focusing of 10 μm beads and Raji cells has been achieved with an efficiency of 99% (beads) and 86% (Raji cells) to a 40 μm wide center region in the 1 mm wide microfluidic channel. This enabled improved optical analysis and reduced bead losses. The loss of beads that ended up in the waste (because printing them as single beads arrangements could not be ensured) was reduced from 52% ± 6% to 28% ± 1%. The piezoelectric transducer employed for cell focusing could be positioned on an outer part of the device, which proves the acoustophoretic focusing to be versatile and adaptable. PMID:25945135

  2. Cavity enhanced telecom heralded single photons for spin-wave solid state quantum memories

    NASA Astrophysics Data System (ADS)

    Rieländer, Daniel; Lenhard, Andreas; Mazzera, Margherita; de Riedmatten, Hugues

    2016-12-01

    We report on a source of heralded narrowband (≈ 3 MHz) single photons compatible with solid-state spin-wave quantum memories based on praseodymium doped crystals. Widely non-degenerate narrow-band photon pairs are generated using cavity enhanced down conversion. One photon from the pair is at telecom wavelengths and serves as heralding signal, while the heralded single photon is at 606 nm, resonant with an optical transition of Pr3+:Y2SiO5. The source offers a heralding efficiency of 28% and a generation rate exceeding 2000 pairs mW-1 in a single-mode. The single photon nature of the heralded field is confirmed by a direct antibunching measurement, with a measured antibunching parameter down to 0.010(4). Moreover, we investigate in detail photon cross- and autocorrelation functions proving non-classical correlations between the two photons. The results presented in this paper offer prospects for the demonstration of single photon spin-wave storage in an on-demand solid state quantum memory, heralded by a telecom photon.

  3. Plasmon Coupling Enhanced Raman Scattering Nanobeacon for Single-Step, Ultrasensitive Detection of Cholera Toxin.

    PubMed

    Zhang, Chong-Hua; Liu, Ling-Wei; Liang, Ping; Tang, Li-Juan; Yu, Ru-Qin; Jiang, Jian-Hui

    2016-08-02

    We report the development of a novel plasmon coupling enhanced Raman scattering (PCERS) method, PCERS nanobeacon, for ultrasensitive, single-step, homogeneous detection of cholera toxin (CT). This method relies on our design of the plasmonic nanoparticles, which have a bilayer phospholipid coating with embedded Raman indicators and CT-binding ligands of monosialoganglioside (GM1). This design allows a facile synthesis of the plasmonic nanoparticle via two-step self-assembly without any specific modification or chemical immobilization. The realization of tethering GM1 on the surface imparts the plasmonic nanoparticles with high affinity, excellent specificity, and multivalence for interaction with CT. The unique lipid-based bilayer coated structure also affords excellent biocompatibility and stability for the plasmonic nanoparticles. The plasmonic nanoparticles are able to show substantial enhancement of the surface-enhanced Raman scattering (SERS) signals in a single-step interaction with CT, because of their assembly into aggregates in response to the CT-sandwiched interactions. The results reveal that the developed nanobeacon provides a simple but ultrasensitive sensor for rapid detection of CT with a large signal-to-background ratio and excellent reproducibility in a wide dynamic range, implying its potential for point-of-care applications in preventive and diagnostic monitoring of cholera.

  4. Permeability enhancement of Escherichia coli by single-walled carbon nanotube treatment.

    PubMed

    Mosleh, Abdollah; Heintz, Anna; Lim, Ki-Taek; Kim, Jin-Woo; Beitle, Robert

    2017-03-06

    This research investigated the use of single-walled carbon nanotubes (SWNTs) as an additive to increase the permeability of a bacterial cell wall. Recombinant Escherichia coli BL21 (DE3) that expressed β-lactamase were exposed to SWNTs under various levels of concentration and agitation. Activity of β-lactamase in the culture fluid and Transmission Electron Microscopy (TEM) were used to determine the amount of released protein, and visually examine the permeability enhancement of the cells. It was found that β-lactamase release in the culture fluid occurred in a dose dependent manner with treatment by SWNTs and was also dependent on agitation rate. Based on TEM, this treatment successfully caused an increase in permeability without significant damage to the cell wall. Consequently, SWNTs can be used as an enhancement agent to cause the release of intracellular proteins. This article is protected by copyright. All rights reserved.

  5. Double-dark-resonance-enhanced Kerr nonlinearity in a single layer of graphene nanostructure

    NASA Astrophysics Data System (ADS)

    Solookinejad, Gh.; Panahi, M.; Ahmadi Sangachin, E.; Hossein Asadpour, Seyyed

    2016-08-01

    In this paper, a novel scheme is proposed for the giant enhanced Kerr nonlinearity in a single layer of graphene nanostructure based on quantum optics and nonlinear optical sciences. The linear and the nonlinear susceptibility of the monolayer graphene system are presented in details by using the density matrix method and perturbation theory. After deriving the equations of motion in the steady-state regime, we analytically solve the linear and nonlinear susceptibility of the system. Our numerical results show that the giant enhanced Kerr nonlinearity can be obtained in the double-dark-resonance condition with zero linear and nonlinear absorption. Our results may have potential applications in quantum information science in infrared and terahertz regimes.

  6. 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.

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

    PubMed Central

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

    2014-01-01

    In cancer imaging, nanoparticle biodistribution is typically visualised in living subjects using ‘bulk’ imaging modalities such as magnetic resonance imaging, computerized tomography and whole-body fluorescence. As such the 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 ie, 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. Next, we 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 p.i.). The remarkable selectivity of this tumour targeting mechanism demonstrates an advanced immune-based delivery strategy for enhancing specific tumour delivery with substantial penetration. PMID:24727688

  8. Effective energy harvesting from a single electrode based triboelectric nanogenerator

    NASA Astrophysics Data System (ADS)

    Kaur, Navjot; Bahadur, Jitendra; Panwar, Vinay; Singh, Pushpendra; Rathi, Keerti; Pal, Kaushik

    2016-12-01

    The arch-shaped single electrode based triboelectric nanogenerator (TENG) is fabricated using thin film of reduced graphene oxide nanoribbons (rGONRs) with polyvinylidene fluoride (PVDF) polymer used as binder to effectively convert mechanical energy into electrical energy. The incorporation of rGONRs in PVDF polymer enhances average surface roughness of rGONRs/PVDF thin film. With the combination of the enhancement of average roughness and production of functional groups, which indicate improve charge storage capacity of prepared film. Furthermore, the redox peaks obtained through cyclic voltammetry were identified more in rGONRs/PVDF composite in comparison to pristine rGONRs to confirm charge transfer capability of film. Herein, the output performance was discussed experimentally as well as theoretically, maximum voltage was obtained to be 0.35 V. The newly designed TENG to harvest mechanical energy and opens up many new avenues of research in the energy harvesting applications.

  9. Effective energy harvesting from a single electrode based triboelectric nanogenerator

    PubMed Central

    Kaur, Navjot; Bahadur, Jitendra; Panwar, Vinay; Singh, Pushpendra; Rathi, Keerti; Pal, Kaushik

    2016-01-01

    The arch-shaped single electrode based triboelectric nanogenerator (TENG) is fabricated using thin film of reduced graphene oxide nanoribbons (rGONRs) with polyvinylidene fluoride (PVDF) polymer used as binder to effectively convert mechanical energy into electrical energy. The incorporation of rGONRs in PVDF polymer enhances average surface roughness of rGONRs/PVDF thin film. With the combination of the enhancement of average roughness and production of functional groups, which indicate improve charge storage capacity of prepared film. Furthermore, the redox peaks obtained through cyclic voltammetry were identified more in rGONRs/PVDF composite in comparison to pristine rGONRs to confirm charge transfer capability of film. Herein, the output performance was discussed experimentally as well as theoretically, maximum voltage was obtained to be 0.35 V. The newly designed TENG to harvest mechanical energy and opens up many new avenues of research in the energy harvesting applications. PMID:27958317

  10. 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.

  11. 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.

  12. Single bead-based electrochemical biosensor

    PubMed Central

    Liu, Changchun; Schrlau, Michael G.; Bau, Haim H.

    2009-01-01

    A simple, robust, single bead-based electrochemical biosensor was fabricated and characterized. The sensor’s working electrode consists of an electrochemically-etched platinum wire, with a nominal diameter of 25 μm, hermetically heat-fusion sealed in a pulled glass capillary (micropipette). The sealing process does not require any epoxy or glue. A commercially available, densely functionalized agarose bead was mounted on the tip of the etched platinum wire. The use of a pre-functionalized bead eliminates the tedious and complicated surface functionalization process that is often the bottleneck in the development of electrochemical biosensors. We report on the use of a biotin agarose bead-based, micropipette, electrochemical (Bio-BMP) biosensor to monitor H2O2 concentration and the use of a streptavidin bead-based, micropipette, electrochemical (SA-BMP) biosensor to detect DNA amplicons. The Bio-BMP biosensor’s response increased linearly as the H2O2 concentration increased in the range from 1×10−6 to 1.2×10−4 M with a detection limit of 5×10−7 M. The SA-BMP was able to detect the amplicons of 1 pg DNA template of B. Cereus bacteria, thus providing better detection sensitivity than conventional gel-based electropherograms. PMID:19767195

  13. Nanowire-based single-cell endoscopy

    NASA Astrophysics Data System (ADS)

    Yan, Ruoxue; Park, Ji-Ho; Choi, Yeonho; Heo, Chul-Joon; Yang, Seung-Man; Lee, Luke P.; Yang, Peidong

    2012-03-01

    One-dimensional smart probes based on nanowires and nanotubes that can safely penetrate the plasma membrane and enter biological cells are potentially useful in high-resolution and high-throughput gene and drug delivery, biosensing and single-cell electrophysiology. However, using such probes for optical communication across the cellular membrane at the subwavelength level remains limited. Here, we show that a nanowire waveguide attached to the tapered tip of an optical fibre can guide visible light into intracellular compartments of a living mammalian cell, and can also detect optical signals from subcellular regions with high spatial resolution. Furthermore, we show that through light-activated mechanisms the endoscope can deliver payloads into cells with spatial and temporal specificity. Moreover, insertion of the endoscope into cells and illumination of the guided laser did not induce any significant toxicity in the cells.

  14. Multisensory enhancement of electromotor responses to a single moving object.

    PubMed

    Pluta, Scott R; Kawasaki, Masashi

    2008-09-01

    Weakly electric fish possess three cutaneous sensory organs structured in arrays with overlapping receptive fields. Theoretically, these tuberous electrosensory, ampullary electrosensory and mechanosensory lateral line receptors receive spatiotemporally congruent stimulation in the presence of a moving object. The current study is the first to quantify the magnitude of multisensory enhancement across these mechanosensory and electrosensory systems during moving-object recognition. We used the novelty response of a pulse-type weakly electric fish to quantitatively compare multisensory responses to their component unisensory responses. Principally, we discovered that multisensory novelty responses are significantly larger than their arithmetically summed component unisensory responses. Additionally, multimodal stimulation yielded a significant increase in novelty response amplitude, probability and the rate of a high-frequency burst, known as a ;scallop'. Supralinear multisensory enhancement of the novelty response may signify an augmentation of perception driven by the ecological significance of multimodal stimuli. Scalloping may function as a sensory scan aimed at rapidly facilitating the electrolocation of novel stimuli.

  15. Systematic investigation of resonance-induced single-harmonic enhancement in the extreme-ultraviolet range

    SciTech Connect

    Ganeev, R. A.; Bom, L. B. Elouga; Kieffer, J.-C.; Ozaki, T.

    2007-06-15

    We demonstrate the intensity enhancement of single harmonics in high-order harmonic generation from laser plasma. We identified several targets (In, Sn, Sb, Cr, and Mn) that demonstrate resonance-induced enhancement of single harmonic, that are spectrally close to ionic transitions with strong oscillator strengths. We optimized and obtained enhancements of the 13th, 17th, 21st, 29th, and 33rd harmonics from the above targets, by varying the chirp of the 800 nm wavelength femtosecond laser. We also observe harmonic enhancement by using frequency-doubled pump laser (400 nm wavelength). For Mn plasma pumped by the 400 nm wavelength laser, the maximum order of the enhanced harmonic observed was the 17th order ({lambda}=23.5 nm), which corresponds to the highest photon energy (52.9 eV) reported for an enhanced single harmonic.

  16. 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.

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

    SciTech Connect

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

    2014-10-06

    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.

  18. Single-Walled Carbon Nanotubes Enhance the Efficiency and Stability of Mesoscopic Perovskite Solar Cells.

    PubMed

    Batmunkh, Munkhbayar; Shearer, Cameron J; Bat-Erdene, Munkhjargal; Biggs, Mark J; Shapter, Joseph G

    2017-06-14

    Carbon nanotubes are 1D nanocarbons with excellent properties and have been extensively used in various electronic and optoelectronic device applications including solar cells. Herein, we report a significant enhancement in the efficiency and stability of perovskite solar cells (PSCs) by employing single-walled carbon nanotubes (SWCNTs) in the mesoporous photoelectrode. It was found that SWCNTs provide both rapid electron transfer and advantageously shifts the conduction band minimum of the TiO2 photoelectrode and thus enhances all photovoltaic parameters of PSCs. The TiO2-SWCNTs photoelectrode based PSC device exhibited a power conversion efficiency (PCE) of up to 16.11%, while the device fabricated without SWCNTs displayed an efficiency of 13.53%. More importantly, we found that the SWCNTs in the TiO2 nanoparticles (TiO2 NPs) based photoelectrode suppress the hysteresis behavior and significantly enhance both the light and long-term storage stability of the PSC devices. The present work provides important guidance for future investigations in utilizing carbonaceous materials for solar cells.

  19. Single-molecule FRET experiments with a red-enhanced custom technology SPAD

    PubMed Central

    Panzeri, Francesco; Ingargiola, Antonino; Lin, Ron R.; Sarkhosh, Niusha; Gulinatti, Angelo; Rech, Ivan; Ghioni, Massimo; Cova, Sergio; Weiss, Shimon; Michalet, Xavier

    2013-01-01

    Single-molecule fluorescence spectroscopy of freely diffusing molecules in solution is a powerful tool used to investigate the properties of individual molecules. Single-Photon Avalanche Diodes (SPADs) are the detectors of choice for these applications. Recently a new type of SPAD detector was introduced, dubbed red-enhanced SPAD (RE-SPAD), with good sensitivity throughout the visible spectrum and with excellent timing performance. We report a characterization of this new detector for single-molecule fluorescence resonant energy transfer (smFRET) studies on freely diffusing molecules in a confocal geometry and alternating laser excitation (ALEX) scheme. We use a series of doubly-labeled DNA molecules with donor-to-acceptor distances covering the whole range of useful FRET values. Both intensity-based (μs-ALEX) and lifetime-based (ns-ALEX) measurements are presented and compared to identical measurements performed with standard thick SPADs. Our results demonstrate the great potential of this new detector for smFRET measurements and beyond. PMID:24371508

  20. Quantum-Dot Single-Photon Sources for Entanglement Enhanced Interferometry.

    PubMed

    Müller, M; Vural, H; Schneider, C; Rastelli, A; Schmidt, O G; Höfling, S; Michler, P

    2017-06-23

    Multiphoton entangled states such as "N00N states" have attracted a lot of attention because of their possible application in high-precision, quantum enhanced phase determination. So far, N00N states have been generated in spontaneous parametric down-conversion processes and by mixing quantum and classical light on a beam splitter. Here, in contrast, we demonstrate superresolving phase measurements based on two-photon N00N states generated by quantum dot single-photon sources making use of the Hong-Ou-Mandel effect on a beam splitter. By means of pulsed resonance fluorescence of a charged exciton state, we achieve, in postselection, a quantum enhanced improvement of the precision in phase uncertainty, higher than prescribed by the standard quantum limit. An analytical description of the measurement scheme is provided, reflecting requirements, capability, and restraints of single-photon emitters in optical quantum metrology. Our results point toward the realization of a real-world quantum sensor in the near future.

  1. 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.

  2. 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

  3. Quantum-Dot Single-Photon Sources for Entanglement Enhanced Interferometry

    NASA Astrophysics Data System (ADS)

    Müller, M.; Vural, H.; Schneider, C.; Rastelli, A.; Schmidt, O. G.; Höfling, S.; Michler, P.

    2017-06-01

    Multiphoton entangled states such as "N00N states" have attracted a lot of attention because of their possible application in high-precision, quantum enhanced phase determination. So far, N00N states have been generated in spontaneous parametric down-conversion processes and by mixing quantum and classical light on a beam splitter. Here, in contrast, we demonstrate superresolving phase measurements based on two-photon N00N states generated by quantum dot single-photon sources making use of the Hong-Ou-Mandel effect on a beam splitter. By means of pulsed resonance fluorescence of a charged exciton state, we achieve, in postselection, a quantum enhanced improvement of the precision in phase uncertainty, higher than prescribed by the standard quantum limit. An analytical description of the measurement scheme is provided, reflecting requirements, capability, and restraints of single-photon emitters in optical quantum metrology. Our results point toward the realization of a real-world quantum sensor in the near future.

  4. Electromagnetic contributions to single-molecule sensitivity in surface-enhanced Raman scattering

    NASA Astrophysics Data System (ADS)

    Xu, Hongxing; Aizpurua, Javier; Käll, Mikael; Apell, Peter

    2000-09-01

    We examine whether single molecule sensitivity in surface-enhanced Raman scattering (SERS) can be explained in the framework of classical electromagnetic theory. The influence of colloid particle shape and size, composition (Ag or Au) and interparticle separation distance on the wavelength-dependent SERS enhancement factor is reported. Our calculations indicate that the maximum enhancement factor achievable through electromagnetics is of the order 1011. This is obtained only under special circumstances, namely at interstitial sites between particles and at locations outside sharp surface protrusions. The comparative rarity of such sites, together with the extreme spatial localization of the enhancement they provide, can qualitatively explain why only very few surface sites seem to contribute to the measured signal in single-molecule SERS experiments. Enhancement factors of the order 1014-1015, which have been reported in recent experiments, are likely to involve additional enhancement mechanisms such as chemisorption induced resonance Raman effects.

  5. 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.

  6. 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.

  7. 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.

  8. Incorporating single-step strategy into random regression model to enhance genomic prediction of longitudinal trait.

    PubMed

    Kang, H; Zhou, L; Mrode, R; Zhang, Q; Liu, J-F

    2016-12-28

    In prediction of genomic values, single-step method has been demonstrated to outperform multi-step methods. In statistical analyses of longitudinal traits, random regression test-day model (RR-TDM) has clear advantages over other models. Our goal in this study was to evaluate the performance of the model integrating both single-step and RR-TDM prediction methods, called single-step random regression test-day model (SS RR-TDM), in comparison with the pedigree-based RR-TDM and genomic best linear unbiased prediction (GBLUP) model. We performed extensive simulations to exploit potential advantages of SS RR-TDM over the other two models under various scenarios with different level of heritability, number of quantitative trait loci as well as selection scheme. SS RR-TDM was found to achieve the highest accuracy and unbiasedness under all scenarios, exhibiting robust prediction ability in longitudinal trait analyses. Moreover, SS RR-TDM showed better persistency of accuracy over generations than GBLUP model. In addition, we also found that the SS RR-TDM had advantages over RR-TDM and GBLUP in terms of a real data set of human contributed by the Genetic Analysis Workshop 18. The findings in our study firstly proved the feasibility and advantages of the SS RR-TDM, and further enhanced strategies for the genomic prediction of longitudinal traits in the future.Heredity advance online publication, 28 December 2016; doi:10.1038/hdy.2016.91.

  9. Analysis and enhancement of 3D shape accuracy in a single-shot LIDAR sensor

    NASA Astrophysics Data System (ADS)

    Han, Munhyun; Choi, Gudong; Song, Minhyup; Seo, Hongseok; Mheen, Bongki

    2017-02-01

    The accuracy of timing jitter is of prime importance in the prevalent utilization of Light Detection and Ranging (LiDAR) technology for the real-time high-resolution three-dimensional (3D) image sensor, especially for relatively small object detection in various applications, such as in the fully automated car navigation and military surveillance. To assess the accuracy of timing, that is, the accuracy of the distance or three-dimensional shape, the standard deviation method can be used in the Time-of-Flight (ToF) LiDAR technology. While most timing jitter analyses are mainly based on a fiber-network or open space at a relatively short range distance, more accurate analyses are required to extract more information about the timing jitter at in a 3D image sensor long-range free space conditions for extended LiDAR-related applications. In this paper, utilizing a Single-Shot LiDAR System (SSLs) model with a 400 MHz wideband InGaAs Avalanche Photodiode and a 1550 nm 2 nsec full width at half maximum MOPA fiber laser, we analyzed the precise timing jitter for the implemented SSLs to characterize the measurement results. Additionally, we report the enhanced results for the resolution and precision in the given SSLs using the spline interpolation method from the measured results, and multiple-shot averaging (MSA). Finally, by adapting the proposed method to an implemented high resolution 3D LiDAR prototype, called the STUD LiDAR prototype, which can be understood as one kind of SSLs because it has a single source and a single detector as in a SSLs, we observed and analyzed the 3D resolution enhancement.

  10. Plasmonic-enhanced two-photon fluorescence with single gold nanoshell

    NASA Astrophysics Data System (ADS)

    Zhang, TianYue; Lu, GuoWei; Shen, HongMing; Perriat, P.; Martini, M.; Tillement, O.; Gong, QiHuang

    2014-06-01

    Single gold nanoshell with mutilpolar plasmon resonances is proposed to enhance two-photon fluorescence efficiently. The single emitter single nanoshell configuration is studied systematically by employing the finite-difference time-domain method. The emitter located inside or outside the nanoshell at various positions leads to a significantly different enhancement effect. The fluorescent emitter placed outside the nanoshell can achieve large fluorescence intensity given that both the position and orientation of the emission dipole are optimally controlled. In contrast, for the case of the emitter placed inside the nanoshell, it can experience substantial two-photon fluorescence enhancement without strict requirements upon the position and dipole orientations. Metallic nanoshell encapsulating many fluorescent emitters should be a promising nanocomposite configuration for bright two-photon fluorescence label. The results provide a comprehensive understanding about the plasmonic-enhanced two-photon fluorescence behaviors, and the nanocomposite configuration has great potential for optical detecting, imaging and sensing in biological applications.

  11. 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

  12. Single-Crystalline Ultrathin Co3O4 Nanosheets with Massive Vacancy Defects for Enhanced Electrocatalysis

    DOE PAGES

    Cai, Zhao; Bi, Yongmin; Hu, Enyuan; ...

    2017-09-18

    The role of vacancy defects is demonstrated to be positive in various energy-related processes. However, introducing vacancy defects into single-crystalline nanostructures with given facets and studying their defect effect on electrocatalytic properties remains a great challenge. Here this paper deliberately introduces oxygen defects into single-crystalline ultrathin Co3O4 nanosheets with O-terminated {111} facets by mild solvothermal reduction using ethylene glycol under alkaline condition. As-prepared defect-rich Co3O4 nanosheets show a low overpotential of 220 mV with a small Tafel slope of 49.1 mV dec-1 for the oxygen evolution reaction (OER), which is among the best Co-based OER catalysts to date and evenmore » more active than the state-of-the-art IrO2 catalyst. Such vacancy defects are formed by balancing with reducing environments under solvothermal conditions, but are surprisingly stable even after 1000 cycles of scanning under OER working conditions. Density functional theory plus U calculation attributes the enhanced performance to the oxygen vacancies and consequently exposed second-layered Co metal sites, which leads to the lowered OER activation energy of 2.26 eV and improved electrical conductivity. Finally, this mild solvothermal reduction concept opens a new door for the understanding and future designing of advanced defect-based electrocatalysts.« less

  13. Single-transducer dual-frequency ultrasound generation to enhance acoustic cavitation.

    PubMed

    Liu, Hao-Li; Hsieh, Chao-Ming

    2009-03-01

    Dual- or multiple-frequency ultrasound stimulation is capable of effectively enhancing the acoustic cavitation effect over single-frequency ultrasound. Potential application of this sonoreactor design has been widely proposed such as on sonoluminescence, sonochemistry enhancement, and transdermal drug release enhancement. All currently available sonoreactor designs employed multiple piezoelectric transducers for generating single-frequency ultrasonic waves separately and then these waves were mixed and interfered in solutions. The purpose of this research is to propose a novel design of generating dual-frequency ultrasonic waves with single piezoelectric elements, thereby enhancing acoustic cavitation. Macroscopic bubbles were detected optically, and they were quantified at either a single-frequency or for different frequency combinations for determining their efficiency for enhancing acoustic cavitation. Visible bubbles were optically detected and hydrogen peroxide was measured to quantify acoustic cavitation. Test water samples with different gas concentrations and different power levels were used to determine the efficacy of enhancing acoustic cavitation of this design. The spectrum obtained from the backscattered signals was also recorded and examined to confirm the occurrence of stable cavitation. The results confirmed that single-element dual-frequency ultrasound stimulation can enhance acoustic cavitation. Under certain testing conditions, the generation of bubbles can be enhanced up to a level of five times higher than the generation of bubbles in single-frequency stimulation, and can increase the hydrogen peroxide production up to an increase of one fold. This design may serve as a useful alternative for future sonoreactor design owing to its simplicity to produce dual- or multiple-frequency ultrasound.

  14. 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.

  15. 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

  16. Investigation of maximum optical enhancement in single gold nanowires and triple nanowire arrays

    NASA Astrophysics Data System (ADS)

    Saylor, Cameron; Novak, Eric; Debu, Desalegn; Herzog, Joseph B.

    2015-01-01

    This work thoroughly investigates gold nanowires with various cross-sectional geometries and patterns. The study has determined the effect of the cross section aspect ratio on its maximum optical enhancement. The plasmonic optical enhancement properties of single gold nanowires and an array of three nanowires were investigated using finite element method simulations. The results indicate a significant dependence of the optical enhancement on both the thickness and width of the nanowires. From the simulation data, an equation for each geometry (single and triple array) was found that relates the dimensions and incident wavelength to the optical enhancement. These relationships can be a valuable resource while designing nanowires to optimize the dimensions and provide the maximum possible optical enhancement.

  17. 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.

  18. Intensity based sensor based on single mode optical fiber patchcords

    NASA Astrophysics Data System (ADS)

    Bayuwati, Dwi; Waluyo, Tomi Budi; Mulyanto, Imam

    2016-11-01

    This paper describes the use of several single mode (SM) fiber patchcords available commercially in the market for intensity based sensor by taking the benefit of bending loss phenomenon. Firtsly, the full transmission spectrum of all fiber patchcords were measured and analyzed to examine its bending properties at a series of wavelength using white light source and optical spectrum analyzer. Bending spectral at various bending diameter using single wavelength light sources were then measured for demonstration.Three good candidates for the intensity based sensor are SM600 fiber patchcord with 970 nm LED, SMF28 fiber patchcord with 1050 nm LED and 780HP fiber patchcord with 1310 nm LED which have noticeable bending sensitive area. Experiments show that the combination of the SMF28with 1050 nm LED has 30 mm measurement range which is the widest; with sensitivity 0.107 dB/mm and resolution 0.5 mm compared with combination of SM600 patchcord and LED 970 nm which has the best sensitivity (0.891 dB/mm) and resolution (0.06 mm) but smaller range measurement (10 mm). Some suitable applications for each fiber patchcord - light source pair have also been discussed.

  19. Enhanced Telecom Emission from Single Group-IV Quantum Dots by Precise CMOS-Compatible Positioning in Photonic Crystal Cavities.

    PubMed

    Schatzl, Magdalena; Hackl, Florian; Glaser, Martin; Rauter, Patrick; Brehm, Moritz; Spindlberger, Lukas; Simbula, Angelica; Galli, Matteo; Fromherz, Thomas; Schäffler, Friedrich

    2017-03-15

    Efficient coupling to integrated high-quality-factor cavities is crucial for the employment of germanium quantum dot (QD) emitters in future monolithic silicon-based optoelectronic platforms. We report on strongly enhanced emission from single Ge QDs into L3 photonic crystal resonator (PCR) modes based on precise positioning of these dots at the maximum of the respective mode field energy density. Perfect site control of Ge QDs grown on prepatterned silicon-on-insulator substrates was exploited to fabricate in one processing run almost 300 PCRs containing single QDs in systematically varying positions within the cavities. Extensive photoluminescence studies on this cavity chip enable a direct evaluation of the position-dependent coupling efficiency between single dots and selected cavity modes. The experimental results demonstrate the great potential of the approach allowing CMOS-compatible parallel fabrication of arrays of spatially matched dot/cavity systems for group-IV-based data transfer or quantum optical systems in the telecom regime.

  20. 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

    2007-05-08

    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.

  1. 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.

  2. Enhancing atlas based segmentation with multiclass linear classifiers.

    PubMed

    Sdika, Michaël

    2015-12-01

    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. 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. 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. 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.

  3. Classification of single particle optical scattering patterns by the spectrum enhancement algorithm

    NASA Astrophysics Data System (ADS)

    Crosta, Giovanni F.

    2005-11-01

    Airborne material particles in the 5μm size range have been collected, resuspended and analyzed by the TAOS (two-dimensional angular optical scattering) technique. The corresponding patterns of light intensity scattered by single particles have been automatically classified by an algorithm based on "spectrum enhancement", multivariate statistics and supervised optimization. The enhanced spectrum has resulted from some non-linear operations on fractional spatial derivatives of the pattern. It has yielded morphological descriptors of the pattern. A multiobjective optimization algorithm has included principal components analysis and has maximized pairwise discrimination between classes. The classifier has been trained by TAOS patterns from 10μm polystyrene spheres (P) and background aerosol particles (B). Then it has been applied to recognize patterns from airborne debris (A) sampled on a car racing track. Training with at least 10 patterns per class has discriminated P and B from A at confidence levels >=90%. Training by samples of smaller sizes (e.g., 5P and 12B patterns) has obviously yielded lower confidence levels (65% in B-A discrimination).

  4. 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

  5. Enhanced single-photon emission from a diamond-silver aperture

    NASA Astrophysics Data System (ADS)

    Choy, Jennifer T.; Hausmann, Birgit J. M.; Babinec, Thomas M.; Bulu, Irfan; Khan, Mughees; Maletinsky, Patrick; Yacoby, Amir; Lončar, Marko

    2011-12-01

    Solid-state quantum emitters, such as the nitrogen-vacancy centre in diamond, are robust systems for practical realizations of various quantum information processing protocols and nanoscale magnetometry schemes at room temperature. Such applications benefit from the high emission efficiency and flux of single photons, which can be achieved by engineering the electromagnetic environment of the emitter. One attractive approach is based on plasmonic resonators, in which sub-wavelength confinement of optical fields can strongly modify the spontaneous emission of a suitably embedded dipole despite having only modest quality factors. Meanwhile, the scalability of solid-state quantum systems critically depends on the ability to control such emitter-cavity interaction in a number of devices arranged in parallel. Here, we demonstrate a method to enhance the radiative emission rate of single nitrogen-vacancy centres in ordered arrays of plasmonic apertures that promises greater scalability over the previously demonstrated bottom-up approaches for the realization of on-chip quantum networks.

  6. Nanoantenna-enhanced ultrafast nonlinear spectroscopy of a single gold nanoparticle

    PubMed Central

    Schumacher, Thorsten; Kratzer, Kai; Molnar, David; Hentschel, Mario; Giessen, Harald; Lippitz, Markus

    2011-01-01

    Optical nanoantennas, just like their radio-frequency equivalents, enhance the light-matter interaction in their feed gap. Antenna enhancement of small signals promises to open a new regime in linear and nonlinear spectroscopy on the nanoscale. Without antennas especially the nonlinear spectroscopy of single nanoobjects is very demanding. Here we present the first antenna-enhanced ultrafast nonlinear optical spectroscopy. In particular, we use the antenna to determine the nonlinear transient absorption signal of a single gold nanoparticle caused by mechanical breathing oscillations. We increase the signal amplitu-de by an order of magnitude, which is in good agreement with our analytical and numerical models. Our method will find applications in linear and nonlinear spectroscopy of single nanoobjects, especially in simplifying such challenging experiments as transient absorption or multiphoton excitation.

  7. Livewire based single still image segmentation

    NASA Astrophysics Data System (ADS)

    Zhang, Jun; Yang, Rong; Liu, Xiaomao; Yue, Hao; Zhu, Hao; Tian, Dandan; Chen, Shu; Li, Yiquan; Tian, Jinwen

    2011-11-01

    In the application of the video contactless measurement, the quality of the image taken from underwater is not very well. It is well known that automatic image segmental method cannot provide acceptable segmentation result with low quality single still image. Snake algorithm can provide better result in this case with the aiding of human. However, sometimes the segmental result of Snake may far from the initial segmental contour drawn by user. Livewire algorithm can keep the location of the seed points that user selected nailed from the beginning to the end. But the contour may have burrs when the image's noise is quite high and the contrast is low. In this paper, we modified the cost function of Livewire algorithm and proposed a new segmentation method that can be used for single still image segmentation with high noise and low contrast.

  8. Spatially resolved study of InGaN photoluminescence enhancement by single Ag nanoparticles

    NASA Astrophysics Data System (ADS)

    Dobrovolskas, D.; Mickevičius, J.; Tamulaitis, G.; Chen, H. S.; Chen, C. P.; Jung, Y. L.; Kiang, Y. W.; Yang, C. C.

    2013-04-01

    Spatially resolved photoluminescence (PL) of an InGaN/GaN multiple quantum well (QW) structure covered by Ag nanoparticles (NPs) is studied using confocal microscopy. Up to fourfold enhancement of PL intensity due to the coupling of the QWs with localized surface plasmons (LSPs) induced on single Ag NPs is demonstrated. The enhancement is accompanied by a redshift of the PL spectral peak position towards the LSP resonance wavelength. The correlation between PL intensity and spectral position indicates that the enhancement is stronger in the sample areas emitting at wavelengths that are a better match with the LSP resonance wavelength. The enhancement of light emission and extraction facilitated by photon coupling with LSP in a single Ag NP is demonstrated.

  9. 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.

  10. Enhanced photoluminescence from single nitrogen-vacancy defects in nanodiamonds coated with phenol-ionic complexes.

    PubMed

    Bray, Kerem; Previdi, Rodolfo; Gibson, Brant C; Shimoni, Olga; Aharonovich, Igor

    2015-03-21

    Fluorescent nanodiamonds are attracting major attention in the field of bio-sensing and bio-labeling. In this work we demonstrate a robust approach to achieve an encapsulation of individual nanodiamonds with phenol-ionic complexes that enhance the photoluminescence from single nitrogen vacancy (NV) centers. We show that single NV centres in the coated nanodiamonds also exhibit shorter lifetimes, opening another channel for high resolution sensing. We propose that the nanodiamond encapsulation reduces the non-radiative decay pathways of the NV color centers. Our results provide a versatile and assessable way to enhance photoluminescence from nanodiamond defects that can be used in a variety of sensing and imaging applications.

  11. Excitation enhancement of CdSe quantum dots by single metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Chen, Yeechi; Munechika, Keiko; Jen-La Plante, Ilan; Munro, Andrea M.; Skrabalak, Sara E.; Xia, Younan; Ginger, David S.

    2008-08-01

    We study plasmon-enhanced fluorescence from CdSe /CdS/CdZnS/ZnS core/shell quantum dots near a variety of Ag and Au nanoparticles. The photoluminescence excitation (PLE) spectrum of quantum dots closely follows the localized surface plasmon resonance (LSPR) scattering spectrum of the nanoparticles. We measure excitation enhancement factors of ˜3 to 10 for different shapes of single metal nanoparticles.

  12. Purcell-Enhanced Single-Photon Emission from Nitrogen-Vacancy Centers Coupled to a Tunable Microcavity

    NASA Astrophysics Data System (ADS)

    Kaupp, Hanno; Hümmer, Thomas; Mader, Matthias; Schlederer, Benedikt; Benedikter, Julia; Haeusser, Philip; Chang, Huan-Cheng; Fedder, Helmut; Hänsch, Theodor W.; Hunger, David

    2016-11-01

    Optical microcavities are a powerful tool for enhancing the fluorescence of individual quantum emitters. However, the broad emission spectra encountered in the solid state at room temperature limit the influence of a cavity, calling for an ultrasmall mode volume. We demonstrate Purcell-enhanced single-photon emission from nitrogen-vacancy centers in nanodiamonds coupled to a tunable fiber-based microcavity with a mode volume down to 1.0 λ3. We record cavity-enhanced fluorescence images and study several single emitters with one cavity. The Purcell effect is evidenced by enhanced fluorescence collection and tunable lifetime modification, and we infer an effective Purcell factor of up to 2. Furthermore, we show an alternative regime for light confinement, where a Fabry-Perot mode is combined with additional mode confinement by the nanocrystal itself. Simulations predict effective Purcell factors of up to 11 for nitrogen-vacancy centers and 63 for silicon-vacancy centers, holding promise for bright single-photon sources and efficient spin readout under ambient conditions.

  13. 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.

  14. Sensitivity Enhancement in Static Solid-State NMR Experiments VIA Single and Multiple Quantum Dipolar Coherences

    PubMed Central

    Gopinath, T.; Veglia, Gianluigi

    2012-01-01

    We present a new method to enhance the sensitivity in static solid-state NMR for a gain in signal-to-noise ratio up to 40%. This sensitivity enhancement is different from the corresponding solution NMR sensitivity enhancement schemes and is achieved by combining single and multiple quantum dipolar coherences. While this new approach is demonstrated for the PISEMA (polarization inversion spin exchange at magic angle) experiment, it can be generalized to the other separated local field experiments for solid-state NMR spectroscopy. This method will have a direct impact on solid-state NMR spectroscopy of liquid crystals as well as membrane proteins aligned in lipid membranes. PMID:19351170

  15. 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.

  16. 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.

  17. Enhancement of spin polarization in transport through protein-like single-helical molecules

    NASA Astrophysics Data System (ADS)

    Wu, Hai-Na; Wang, Xiao; Zhang, Ya-Jing; Yi, Guang-Yu; Gong, Wei-Jiang

    2016-06-01

    We investigate the spin-polarized electron transport through the single-helical molecules connected with two normal metallic leads. On the basis of an effective model Hamiltonian, influences of the structural parameters on the conductance and the spin polarization are calculated by using the Landauer-Büttiker formula. The optimal structural parameters for the maximal spin polarization are analyzed. Our results show that the dephasing term is an important factor to enhance the spin polarization, in addition to the intrinsic parameters of the single-helical molecule. This work can be helpful in optimizing the spin polarization in the protein-like single-helical molecules.

  18. 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.

  19. Fluorescence signals of core-shell quantum dots enhanced by single crystalline gold caps on silicon nanowires

    NASA Astrophysics Data System (ADS)

    Christiansen, S. H.; Chou, J. W.; Becker, M.; Sivakov, V.; Ehrhold, K.; Berger, A.; Chou, W. C.; Chuu, D. S.; Gösele, U.

    2009-04-01

    We use nanoscale (20-300 nm in diameter) single crystalline gold (Au)-caps on silicon nanowires (NWs) grown by the vapor-liquid-solid (VLS) growth mechanism to enhance the fluorescence photoluminescence (PL) signals of highly dilute core/shell CdSeTe/ZnS quantum dots (QDs) in aqueous solution (10-5 M). For NWs without Au-caps, as they appear, for example, after Au etching in aqua regia or buffered KI/I2-solution, essentially no fluorescence signal of the same diluted QDs could be observed. Fluorescence PL signals were measured using excitation with a laser wavelength of 633 nm. The signal enhancement by single crystalline, nanoscale Au-caps is discussed and interpreted based on finite element modeling (FEM).

  20. Mechanical Trap Surface-Enhanced Raman Spectroscopy for Three-Dimensional Surface Molecular Imaging of Single Live Cells.

    PubMed

    Jin, Qianru; Li, Ming; Polat, Beril; Paidi, Santosh K; Dai, Aimee; Zhang, Amy; Pagaduan, Jayson V; Barman, Ishan; Gracias, David H

    2017-03-27

    Reported is a new shell-based spectroscopic platform, named mechanical trap surface-enhanced Raman spectroscopy (MTSERS), for simultaneous capture, profiling, and 3D microscopic mapping of the intrinsic molecular signatures on the membrane of single live cells. By leveraging the functionalization of the inner surfaces of the MTs with plasmonic gold nanostars, and conformal contact of the cell membrane, MTSERS permits excellent signal enhancement, reliably detects molecular signatures, and allows non-perturbative, multiplex 3D surface imaging of analytes, such as lipids and proteins on the surface of single cells. The demonstrated ability underscores the potential of MTSERS to perform 3D spectroscopic microimaging and to furnish biologically interpretable, quantitative, and dynamic molecular maps in live cell populations.

  1. 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…

  2. Enhanced photoluminescence from single nitrogen-vacancy defects in nanodiamonds coated with phenol-ionic complexes

    NASA Astrophysics Data System (ADS)

    Bray, Kerem; Previdi, Rodolfo; Gibson, Brant C.; Shimoni, Olga; Aharonovich, Igor

    2015-03-01

    Fluorescent nanodiamonds are attracting major attention in the field of bio-sensing and bio-labeling. In this work we demonstrate a robust approach to achieve an encapsulation of individual nanodiamonds with phenol-ionic complexes that enhance the photoluminescence from single nitrogen vacancy (NV) centers. We show that single NV centres in the coated nanodiamonds also exhibit shorter lifetimes, opening another channel for high resolution sensing. We propose that the nanodiamond encapsulation reduces the non-radiative decay pathways of the NV color centers. Our results provide a versatile and assessable way to enhance photoluminescence from nanodiamond defects that can be used in a variety of sensing and imaging applications.Fluorescent nanodiamonds are attracting major attention in the field of bio-sensing and bio-labeling. In this work we demonstrate a robust approach to achieve an encapsulation of individual nanodiamonds with phenol-ionic complexes that enhance the photoluminescence from single nitrogen vacancy (NV) centers. We show that single NV centres in the coated nanodiamonds also exhibit shorter lifetimes, opening another channel for high resolution sensing. We propose that the nanodiamond encapsulation reduces the non-radiative decay pathways of the NV color centers. Our results provide a versatile and assessable way to enhance photoluminescence from nanodiamond defects that can be used in a variety of sensing and imaging applications. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr07510b

  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. 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

  5. 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.

  6. Enhanced single-particle brightness and photostability of semiconductor polymer dots by enzymatic oxygen scavenging system

    NASA Astrophysics Data System (ADS)

    Liu, Zhihe; Yang, Yingkun; Sun, Zezhou; Wu, Changfeng

    2016-12-01

    Semiconductor polymer dots (Pdots) are emerging as an excellent fluorescent probe in biology and medicine. However, the photostability of Pdots can't meet the requirements of long term single-particle imaging and tracking applications. Here we describe the enhanced single-particle brightness and photostability of Pdots by using an efficient enzymatic oxygen scavenging system (OSS). Pdots with particle diameters of 21 nm and 43 nm (PFBT21 and PFBT43) were prepared by a nanoprecipitation method. Single-particle imaging and photobleaching were performed to investigate the effect of OSS on the per-particle brightness and photostability of Pdots. Our results indicate that the single-particle brightness of the PFBT21 Pdots in OSS was enhanced nearly two times as compare to the PFBT21 Pdots in water. The photobleaching percentages of PFBT21 and PFBT43 in OSS were determined to be 29% and 33%, respectively. These values are decreased by 2-3 times as compared to those of the same Pdots in water, indicating the significantly improved photostability of Pdots by OSS. This study provides a promising approach for enhancing photostability of Pdots in long term single-particle tracking.

  7. Enhancement of single-walled nanotubes luminescence intensity upon dithiothreitol doping

    NASA Astrophysics Data System (ADS)

    Kurnosov, N. V.; Linnik, A. S.; Leontiev, V. S.; Karachevtsev, V. A.

    2014-09-01

    In the present work the influence of reducing agent dithiothreitol doping on photoluminescence spectra of nanotubes with adsorbed biopolymers (single-stranded DNA and polyC) in aqueous suspensions and films was studied. It is revealed that greater intensity enhancement at 10-3 mol/L dithiothreitol concentration is observed for (7,5) and (6,5) nanotubes in suspension with single-stranded DNA (by more than 150% of initial intensity) comparing to polyC suspension (less than 60%) while for (6,4) and (9,1) nanotubes enhancement is less than 50% for both suspensions. Photoluminescence intensity increasing for nanotube film with DNA is less than 50% without noticeable dependence on nanotube chirality. It is assumed, that different influence of biopolymers on nanotube luminescence intensity enhancement is due to their different coverage of nanotube surface.

  8. Identifying single bases in a DNA oligomer with electron tunnelling

    NASA Astrophysics Data System (ADS)

    Huang, Shuo; He, Jin; Chang, Shuai; Zhang, Peiming; Liang, Feng; Li, Shengqin; Tuchband, Michael; Fuhrmann, Alexander; Ros, Robert; Lindsay, Stuart

    2010-12-01

    It has been proposed that single molecules of DNA could be sequenced by measuring the physical properties of the bases as they pass through a nanopore. Theoretical calculations suggest that electron tunnelling can identify bases in single-stranded DNA without enzymatic processing, and it was recently experimentally shown that tunnelling can sense individual nucleotides and nucleosides. Here, we report that tunnelling electrodes functionalized with recognition reagents can identify a single base flanked by other bases in short DNA oligomers. The residence time of a single base in a recognition junction is on the order of a second, but pulling the DNA through the junction with a force of tens of piconewtons would yield reading speeds of tens of bases per second.

  9. Color hologram reconstruction based on single DMD

    NASA Astrophysics Data System (ADS)

    Xing, Jiang; Zhou, Hao; Wu, Dan; Hou, Jun-jian; Gu, Ji-hua

    2016-09-01

    Because of the magnification chromatic aberration and the transverse chromatic aberration caused from different wavelengths of color lasers in the process of color holographic optoelectronic reconstruction based on DMD, the reconstructed holograms of three color components can not coincide. Firstly, on the reference of blue color component, the magnification chromatic aberration of the original image is eliminated. Secondly, according to the analysis of the incident angles of three lasers, the transverse chromatic aberration is eliminated by adjusting the incident angles. At last, the synthesized color hologram is obtained by means of the experiments based on DMD. The method proposed in this paper does not use any lens, so there is no axial chromatic aberration.

  10. 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.

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

    NASA Astrophysics Data System (ADS)

    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) mg L- 1. The work experimentally evidenced that α-FeOOH colloid does enhance transport of Pu through fractured granites. The fraction of mobile 239Pu (RPu, m = 41.5%) associated with the α-FeOOH of an extremely low colloid concentration (0.2 mg L- 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 1.0 mg L- 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.

  12. Single-quantum-dot-based DNA nanosensor

    NASA Astrophysics Data System (ADS)

    Zhang, Chun-Yang; Yeh, Hsin-Chih; Kuroki, Marcos T.; Wang, Tza-Huei

    2005-11-01

    Rapid and highly sensitive detection of DNA is critical in diagnosing genetic diseases. Conventional approaches often rely on cumbersome, semi-quantitative amplification of target DNA to improve detection sensitivity. In addition, most DNA detection systems (microarrays, for example), regardless of their need for target amplification, require separation of unhybridized DNA strands from hybridized stands immobilized on a solid substrate, and are thereby complicated by solution-surface binding kinetics. Here, we report an ultrasensitive nanosensor based on fluorescence resonance energy transfer (FRET) capable of detecting low concentrations of DNA in a separation-free format. This system uses quantum dots (QDs) linked to DNA probes to capture DNA targets. The target strand binds to a dye-labelled reporter strand thus forming a FRET donor-acceptor ensemble. The QD also functions as a concentrator that amplifies the target signal by confining several targets in a nanoscale domain. Unbound nanosensors produce near-zero background fluorescence, but on binding to even a small amount of target DNA (~50 copies or less) they generate a very distinct FRET signal. A nanosensor-based oligonucleotide ligation assay has been demonstrated to successfully detect a point mutation typical of some ovarian tumours in clinical samples.

  13. Single Quantum-dot-based Aptameric Nanosensor for Cocaine

    PubMed Central

    Zhang, Chun-yang; Johnson, Lawrence W

    2009-01-01

    Recent advances in single-molecule detection, nanotechnology and aptameric sensors hold exciting promise for many potential applications. By functionalizing the surface of a quantum dot (QD) with aptamers which can recognize cocaine, and taking advantage of single-molecule detection and fluorescence resonance energy transfer (FRET) between 605QD and Cy5 and Iowa Black RQ, we develop a single-QD-based aptameric sensor that is capable of sensing the presence of cocaine through both signal-off and signal-on modes. In comparison with the established aptameric sensors, this single-QD-based aptameric sensor has the significant advantages of simple sample preparation, high sensitivity and extremely low sample consumption. With the advance in the development of varieties of aptamers for small molecules, nucleic acids, metal ions and proteins, this single-QD-based aptameric sensor might find wide application in forensic analysis, environmental monitoring and clinic diagnostics. PMID:19298058

  14. The contribution of nonlocal electro-opto-thermal interaction to single molecule nonlinear Raman enhancement.

    PubMed

    Tai, Chao-Yi; Yu, Wen-Hsiang

    2013-10-21

    we develop a precise modelling where nonlocal electro-opto-thermal interactions are comprehensively included for the analysis of nonlinear Raman enhancement and plasmonic heating. An interaction enhancement factor G(IEF) is introduced to quantify the coupling between the electromagnetic field and the temperature field which is rarely considered in the estimation of Raman enhancement. For the case of isolated single nanosphere, G(IEF) can be up to ten, indicating a thermal origin which well explains the observed temperature rise, shortened blinking period, and the nonlinearly enhanced Raman cross-section. For the case of nanodimer, the suppression of plasmon heating was analyzed, demonstrating the great capability to mitigate biomolecular degradation and blinking.

  15. Plasmon assisted enhanced second-harmonic generation in single hybrid Au/ZnS nanowires

    NASA Astrophysics Data System (ADS)

    Jassim, Nadia M.; Wang, Kai; Han, Xiaobo; Long, Hua; Wang, Bing; Lu, Peixiang

    2017-02-01

    We demonstrate the enhanced second-harmonic generation (SHG) in single ZnS nanowires (NWs) attached with gold nanoparticles (Au NPs). The hybrid Au/ZnS NWs with different densities of the attached Au NPs were prepared by a simple solution impregnation method. By comparing with bare ZnS NWs, ∼1.3, ∼6.6, ∼7 and ∼2 times enhancement of SH intensity was achieved in the hybrid Au/ZnS NWs with low, moderate, high and ultrahigh densities of the attached Au NPs, respectively. The enhanced SHG in the hybrid Au/ZnS NWs is attributed to the strong local-fields from the Au cluster under the near-resonant condition, which is supported by the related dark-field scattering spectra. This hybrid Au/ZnS NWs provide a simple platform for enhancing nonlinear optical responses, which have potential applications in nano-probing and nano-sensing.

  16. Systems nanobiology: from quantitative single molecule biophysics to microfluidic-based single cell analysis.

    PubMed

    Martini, Joerg; Hellmich, Wibke; Greif, Dominik; Becker, Anke; Merkle, Thomas; Ros, Robert; Ros, Alexandra; Toensing, Katja; Anselmetti, Dario

    2007-01-01

    Detailed and quantitative information about structure-function relation, concentrations and interaction kinetics of biological molecules and subcellular components is a key prerequisite to understand and model cellular organisation and temporal dynamics. In systems nanobi-ology, cellular processes are quantitatively investigated at the sensitivity level of single molecules and cells. This approach provides direct access to biomolecular information without being statistically ensemble-averaged, their associated distribution functions, and possible subpopulations. Moreover at the single cell level, the interplay of regulated genomic information and proteomic variabilities can be investigated and attributed to functional peculiarities. These requirements necessitate the development of novel and ultrasensitive methods and instruments for single molecule detection, microscopy and spectroscopy for analysis without the need of amplification and preconcentration. In this chapter, we present three methodological applications that demonstrate how quantitative informations can be accessed that are representative for cellular processes or single cell analysis like gene expression regulation, intracellular protein translocation dynamics, and single cell protein fingerprinting. First, the interaction kinetics of transcriptionally regulated DNA-protein interaction can be quantitatively investigated with single molecule force spectroscopy allowing a molecular affinity ranking. Second, intracellular protein dynamics for a transcription regulator migrating form the nucleus to the cytoplasm can be quantitatively monitored by photoactivable GFP and two-photon laser scanning microscopy. And third, a microfluidic-based method for label-free single cell proteomics and fingerprinting and first label-free single cell electropherograms are presented which include the manipulation and steering of single cells in a microfluidic device.

  17. 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.

  18. 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.

  19. Marangoni Convection Assisted Single Molecule Detection with Nanojet Surface Enhanced Raman Spectroscopy.

    PubMed

    Chang, Te-Wei; Wang, Xinhao; Mahigir, Amirreza; Veronis, Georgios; Liu, Gang Logan; Gartia, Manas Ranjan

    2017-08-25

    Many single-molecule (SM) label-free techniques such as scanning probe microscopies (SPM) and magnetic force spectroscopies (MFS) provide high resolution surface topography information, but lack chemical information. Typical surface enhanced Raman spectroscopy (SERS) systems provide chemical information on the analytes, but lack spatial resolution. In addition, a challenge in SERS sensors is to bring analytes into the so-called "hot spots" (locations where the enhancement of electromagnetic field amplitude is larger than 10(3)). Previously described methods of fluid transport around hot spots like thermophoresis, thermodiffusion/Soret effect, and electrothermoplasmonic flow are either too weak or detrimental in bringing new molecules to hot spots. Herein, we combined the resonant plasmonic enhancement and photonic nanojet enhancemnet of local electric field on nonplanar SERS structures, to construct a stable, high-resolution, and below diffraction limit platform for single molecule label-free detection. In addition, we utilize Marangoni convection (mass transfer due to surface tension gradient) to bring new analytes into the hotspot. An enhancement factor of ∼3.6 × 10(10) was obtained in the proposed system. Rhodamine-6G (R6G) detection of up to a concentration of 10(-12) M, an improvement of two orders of magnitude, was achieved using the nanojet effect. The proposed system could provide a simple, high throughput SERS system for single molecule analysis at high spatial resolution.

  20. Variable-Temperature Tip-Enhanced Raman Spectroscopy of Single-Molecule Fluctuations and Dynamics.

    PubMed

    Park, Kyoung-Duck; Muller, Eric A; Kravtsov, Vasily; Sass, Paul M; Dreyer, Jens; Atkin, Joanna M; Raschke, Markus B

    2016-01-13

    Structure, dynamics, and coupling involving single-molecules determine function in catalytic, electronic or biological systems. While vibrational spectroscopy provides insight into molecular structure, rapid fluctuations blur the molecular trajectory even in single-molecule spectroscopy, analogous to spatial averaging in measuring large ensembles. To gain insight into intramolecular coupling, substrate coupling, and dynamic processes, we use tip-enhanced Raman spectroscopy (TERS) at variable and cryogenic temperatures, to slow and control the motion of a single molecule. We resolve intrinsic line widths of individual normal modes, allowing detailed and quantitative investigation of the vibrational modes. From temperature dependent line narrowing and splitting, we quantify ultrafast vibrational dephasing, intramolecular coupling, and conformational heterogeneity. Through statistical correlation analysis of fluctuations of individual modes, we observe rotational motion and spectral fluctuations of the molecule. This work demonstrates single-molecule vibrational spectroscopy beyond chemical identification, opening the possibility for a complete picture of molecular motion ranging from femtoseconds to minutes.

  1. Elucidating the localized plasmonic enhancement effects from a single Ag nanowire in organic solar cells.

    PubMed

    Liu, Xinfeng; Wu, Bo; Zhang, Qing; Yip, Jing Ngei; Yu, Guannan; Xiong, Qihua; Mathews, Nripan; Sum, Tze Chien

    2014-10-28

    The origins of performance enhancement in hybrid plasmonic organic photovoltaic devices are often embroiled in a complex interaction of light scattering, localized surface plasmon resonances, exciton-plasmon energy transfer and even nonplasmonic effects. To clearly deconvolve the plasmonic contributions from a single nanostructure, we herein investigate the influence of a single silver nanowire (NW) on the charge carriers in bulk heterojunction polymer solar cells using spatially resolved optical spectroscopy, and correlate to electrical device characterization. Polarization-dependent photocurrent enhancements with a maximum of ∼ 36% over the reference are observed when the transverse mode of the plasmonic excitations in the Ag NW is activated. The ensuing higher absorbance and light scattering induced by the electronic motion perpendicular to the NW long axis lead to increased exciton and polaron densities instead of direct surface plasmon-exciton energy transfer. Finite-difference time-domain simulations also validate these findings. Importantly, our study at the single nanostructure level explores the fundamental limits of plasmonic enhancement achievable in organic solar cells with a single plasmonic nanostructure.

  2. 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

  3. 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.

  4. Reliability of high power diode laser systems based on single emitters

    NASA Astrophysics Data System (ADS)

    Leisher, Paul; Reynolds, Mitch; Brown, Aaron; Kennedy, Keith; Bao, Ling; Wang, Jun; Grimshaw, Mike; DeVito, Mark; Karlsen, Scott; Small, Jay; Ebert, Chris; Martinsen, Rob; Haden, Jim

    2011-03-01

    Diode laser modules based on arrays of single emitters offer a number of advantages over bar-based solutions including enhanced reliability, higher brightness, and lower cost per bright watt. This approach has enabled a rapid proliferation of commercially available high-brightness fiber-coupled diode laser modules. Incorporating ever-greater numbers of emitters within a single module offers a direct path for power scaling while simultaneously maintaining high brightness and minimizing overall cost. While reports of long lifetimes for single emitter diode laser technology are widespread, the complex relationship between the standalone chip reliability and package-induced failure modes, as well as the impact of built-in redundancy offered by multiple emitters, are not often discussed. In this work, we present our approach to the modeling of fiber-coupled laser systems based on single-emitter laser diodes.

  5. Mobility enhancement and temperature dependence in top-gated single-layer MoS2

    NASA Astrophysics Data System (ADS)

    Ong, Zhun-Yong; Fischetti, Massimo V.

    2013-10-01

    The deposition of a high-κ oxide overlayer is known to significantly enhance the room-temperature electron mobility in single-layer MoS2 (SLM) but not in single-layer graphene. We give a quantitative account of how this mobility enhancement is due to the nondegeneracy of the two-dimensional electron gas system in SLM at accessible temperatures. Using our charged impurity scattering model [Ong and Fischetti, Phys. Rev. BPRBMDO1098-012110.1103/PhysRevB.86.121409 86, 121409 (2012)] and temperature-dependent polarizability, we calculate the charged impurity-limited mobility (μimp) in SLM with and without a high-κ (HfO2) top-gate oxide at different electron densities and temperatures. We find that the mobility enhancement is larger at low electron densities and high temperatures because of finite-temperature screening, thus explaining the enhancement of the mobility observed at room temperature. μimp is shown to decrease significantly with increasing temperature, suggesting that the strong temperature dependence of measured mobilities should not be interpreted as being solely due to inelastic scattering with phonons. We also reproduce the recently seen experimental trend in which the temperature scaling exponent (γ) of μimp∝T-γ is smaller in top-gated SLM than in bare SLM. Finally, we show that ˜37% mobility enhancement can be achieved by reducing the HfO2 thickness from 20 to 2 nm.

  6. 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

  7. Enhanced electrochemical nanoring electrode for analysis of cytosol in single cells.

    PubMed

    Zhuang, Lihong; Zuo, Huanzhen; Wu, Zengqiang; Wang, Yu; Fang, Danjun; Jiang, Dechen

    2014-12-02

    A microelectrode array has been applied for single cell analysis with relatively high throughput; however, the cells were typically cultured on the microelectrodes under cell-size microwell traps leading to the difficulty in the functionalization of an electrode surface for higher detection sensitivity. Here, nanoring electrodes embedded under the microwell traps were fabricated to achieve the isolation of the electrode surface and the cell support, and thus, the electrode surface can be modified to obtain enhanced electrochemical sensitivity for single cell analysis. Moreover, the nanometer-sized electrode permitted a faster diffusion of analyte to the surface for additional improvement in the sensitivity, which was evidenced by the electrochemical characterization and the simulation. To demonstrate the concept of the functionalized nanoring electrode for single cell analysis, the electrode surface was deposited with prussian blue to detect intracellular hydrogen peroxide at a single cell. Hundreds of picoamperes were observed on our functionalized nanoring electrode exhibiting the enhanced electrochemical sensitivity. The success in the achievement of a functionalized nanoring electrode will benefit the development of high throughput single cell electrochemical analysis.

  8. 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 ~\

  9. Heating-Enhanced Dielectrophoresis for Aligned Single-Walled Carbon Nanotube Film of Ultrahigh Density.

    PubMed

    Gu, Qingyuan; Guezo, Maud; Folliot, Hervé; Batte, Thomas; Loualiche, Slimane; Stervinou, Julie

    2017-12-01

    In this paper, we demonstrate that the alignment density of individualized single-walled carbon nanotubes (SWCNTs) can be greatly improved by heating-enhanced dielectrophoresis (HE-DEP) process. The observations by scanning electron microscope (SEM) suggest ultrahigh alignment density and good alignment quality of SWCNTs. The intuitive alignment density of individualized SWCNTs is much higher than the currently reported best results. The reason of this HE-DEP process is explained by simulation work and ascribed to the heating-enhanced convection process, and the "convection force" induced by the heating effect is assessed in a novel way.

  10. 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 .

  11. 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.

  12. 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

  13. Introducing an enhanced recovery after surgery program in colorectal surgery: a single center experience.

    PubMed

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

    2014-12-14

    To study the implementation of an enhanced recovery after surgery (ERAS) program at a large University Hospital from "pilot study" to "standard of care". 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. 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 were observed in 11 cases (7

  14. Enhanced Raman scattering of single nanoparticles in a high-Q whispering-gallery microresonator

    NASA Astrophysics Data System (ADS)

    Liu, Rui-Shan; Jin, Wei-Liang; Yu, Xiao-Chong; Liu, Yong-Chun; Xiao, Yun-Feng

    2015-04-01

    We study Raman scattering of single nanoparticles coupled to a high-Q whispering-gallery microresonator. It is found that cavity resonances greatly enhance the Raman signal, and the enhancement factor is as high as 108. Unlike the noncavity case, the signal power exhibits a nonmonotonic dependence on particle size, and it reaches the maximum when the Rayleigh scattering loss and the cavity intrinsic loss are comparable. We further analyze how the Raman signal intensity is influenced by different parameters including cavity quality factors and taper-cavity coupling strength. The detection limit of observing single-nanoparticle Raman signal is discussed finally. As a potential application, this mechanism may provide an alternative way to detect specific biological targets without the need of precovered biorecognitions.

  15. Largely Enhanced Single-molecule Fluorescence in Plasmonic Nanogaps formed by Hybrid Silver Nanostructures

    PubMed Central

    Zhang, Jian; Lakowicz, Joseph R.

    2013-01-01

    It has been suggested that narrow gaps between metallic nanostructures can be practical for producing large field enhancement. We design a hybrid silver nanostructure geometry in which fluorescent emitters are sandwiched between silver nanoparticles and silver island film (SIF). A desired number of polyelectrolyte layers are deposited on the SIF surface before the self-assembly of a second silver nanoparticle layer. Layer-by-layer configuration provides a well-defined dye position. It allows us to study the photophyical behaviors of fluorophores in the resulting gap at the single molecule level. The enhancement factor of a fluorophore located in the gap is much higher than those on silver surfaces alone and on glass. These effects may be used for increased detectability of single molecules bound to surfaces which contain metallic structures for either biophysical studies or high sensitivity assays. PMID:23373787

  16. 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.

  17. Laser writing of single-crystalline gold substrates for surface enhanced Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Singh, Astha; Sharma, Geeta; Ranjan, Neeraj; Mittholiya, Kshitij; Bhatnagar, Anuj; Singh, B. P.; Mathur, Deepak; Vasa, Parinda

    2017-07-01

    Surface enhanced Raman scattering (SERS) spectroscopy, a powerful contemporary tool for studying low-concentration analytes via surface plasmon induced enhancement of local electric field, is of utility in biochemistry, material science, threat detection, and environmental studies. We have developed a simple, fast, scalable, and relatively low-cost optical method of fabricating and characterizing large-area, reusable and broadband SERS substrates with long storage lifetime. We use tightly focused, intense infra-red laser pulses to write gratings on single-crystalline, Au (1 1 1) gold films on mica which act as SERS substrates. Our single-crystalline SERS substrates compare favourably, in terms of surface quality and roughness, to those fabricated in poly-crystalline Au films. Tests show that our SERS substrates have the potential of detecting urea and 1,10-phenantroline adulterants in milk and water, respectively, at 0.01 ppm (or lower) concentrations.

  18. Enhanced light-harvesting capability for silicon single-nanowire solar cells coupled with metallic cavity.

    PubMed

    Gai, Feng; Zhang, Cheng; Zhan, Yaohui; Li, Xiaofeng

    2016-12-26

    Single-nanowire solar cells (SNSCs) are attracting increasing interest due to their unique optical antenna effect beneficial for achieving higher light-trapping capability. However, for conventional circular-cross-sectional SNSCs, the light-trapping performance is still far from the expectation. Here we demonstrate that integrating a silicon single nanowire into a metallic slit can dramatically enhance the absorption efficiency over almost the whole spectral band due to strengthened optical antenna effect. Especially, it is found that by using finite-size metallic blocks to form a nanoscale metallic cavity, the light-trapping performance of the SNSCs can be further improved. Through examining the detailed optical spectral response, electric field distribution, and cavity dispersion characteristics, the metallic-coupled SNSC system is optimized and the underlying physics are provided. Simulation results indicate that the photocurrent density of the SNSCs coupled with the designed metallic cavity can be enhanced by 44.4% than that of the conventional bare SNSCs.

  19. Plasmonic resonators for enhanced diamond NV-center single photon sources.

    PubMed

    Bulu, Irfan; Babinec, Thomas; Hausmann, Birgit; Choy, Jennifer T; Loncar, Marko

    2011-03-14

    We propose a novel source of non-classical light consisting of plasmonic aperture with single-crystal diamond containing a single Nitrogen-Vacancy (NV) color center. Theoretical calculations of optimal structures show that these devices can simultaneously enhance optical pumping by a factor of 7, spontaneous emission rates by Fp~50 (Purcell factor), and offer collection efficiencies up to 40%. These excitation and collection enhancements occur over a broad range of wavelengths (~30 nm), and are independently tunable with device geometry, across the excitation (~530 nm) and emission (~600-800 nm) spectrum of the NV center. Implementing this system with top-down techniques in bulk diamond crystals will provide a scalable architecture for a myriad of diamond NV center applications.

  20. 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.

  1. Enhancing traditional behavioral parent training for single mothers of children with ADHD.

    PubMed

    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

    2009-03-01

    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 group, a traditional behavioral parent training program, or an enhanced behavioral parent training program -- the Strategies to Enhance Positive Parenting (STEPP) program. Intent-to-treat analysis demonstrated benefits of participating in behavioral parent training, in general, and the STEPP program more specifically at immediate posttreatment on child and parental functioning. Moreover, the STEPP program resulted in increased engagement to treatment. However, results indicated that behavioral parent training does not normalize behavior for most children and treatment gains are not maintained.

  2. 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.

  3. 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

  4. 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.

  5. Base-by-base Ratcheting of Single Stranded DNA through a Solid-State Nanopore

    PubMed Central

    Luan, Binquan; Peng, Hongbo; Polonsky, Stas; Rossnagel, Steve; Stolovitzky, Gustavo; Martyna, Glenn

    2011-01-01

    We investigate the base-by-base translocation dynamics of single-stranded DNA (ssDNA) confined in a solid-state nanopore dressed with an electrostatic trap, using all-atom molecular dynamics (MD) simulation. We observe on the simulation time scale of tens of nanoseconds that ssDNA can be driven through the nanopore in a ratchet-like fashion, with a step size equal to the spacing between neighboring phosphate groups in the ssDNA backbone. A 1D-Langevin-like model is derived from atomistic dynamics which can quantitatively describe simulation results and can be used to study dynamics on longer time-scales. The controlled ratcheting motion of DNA could potentially enhance the signal-to-noise ratio for nanoelectronic DNA sensing technologies. PMID:20867275

  6. 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.

  7. Enhancing radiation tolerance by controlling defect mobility and migration pathways in multicomponent single-phase alloys

    PubMed Central

    Lu, Chenyang; Niu, Liangliang; Chen, Nanjun; Jin, Ke; Yang, Taini; Xiu, Pengyuan; Zhang, Yanwen; Gao, Fei; Bei, Hongbin; Shi, Shi; He, Mo-Rigen; Robertson, Ian M.; Weber, William J.; Wang, Lumin

    2016-01-01

    A grand challenge in material science is to understand the correlation between intrinsic properties and defect dynamics. Radiation tolerant materials are in great demand for safe operation and advancement of nuclear and aerospace systems. Unlike traditional approaches that rely on microstructural and nanoscale features to mitigate radiation damage, this study demonstrates enhancement of radiation tolerance with the suppression of void formation by two orders magnitude at elevated temperatures in equiatomic single-phase concentrated solid solution alloys, and more importantly, reveals its controlling mechanism through a detailed analysis of the depth distribution of defect clusters and an atomistic computer simulation. The enhanced swelling resistance is attributed to the tailored interstitial defect cluster motion in the alloys from a long-range one-dimensional mode to a short-range three-dimensional mode, which leads to enhanced point defect recombination. The results suggest design criteria for next generation radiation tolerant structural alloys. PMID:27976669

  8. 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).

  9. Momentum angular mapping of enhanced Raman scattering of single-walled carbon nanotube

    NASA Astrophysics Data System (ADS)

    Rai, Padmnabh; Singh, Tapender; Brulé, Thibault; Bouhelier, Alexandre; Finot, Eric

    2017-07-01

    We perform momentum mapping of the Raman scattering of individual single-walled carbon nanotubes (SWNTs) or thin ropes of SWNTs enhanced by surface plasmons sustained by either a linear chain of nanoantennas or flower-shaped nanoparticles. The momentum spectroscopy of Raman scattering of the carbon nanotube (CNT) demonstrates the direct verification of momentum selection rules and identifies the characteristic bands of the molecules or the nanomaterials under scrutiny. The characteristic vibrational signatures of the D, G-, and G bands provide an isotropic response in k-space irrespective of the arrangement of the enhancing platform. However, other dispersive or double resonance bands, such as D-, D+, D', M, and iTOLA bands appear as a dipolar emission oriented towards the long axis of the CNT regardless of the CNT orientation but strongly depend on the patterning of enhancement of the electromagnetic field.

  10. Enhancing radiation tolerance by controlling defect mobility and migration pathways in multicomponent single-phase alloys

    SciTech Connect

    Lu, Chenyang; Niu, Liangliang; Chen, Nanjun; Jin, Ke; Yang, Taini; Xiu, Pengyuan; Zhang, Yanwen; Gao, Fei; Bei, Hongbin; Shi, Shi; He, Mo-Rigen; Robertson, Ian M.; Weber, William J.; Wang, Lumin

    2016-12-15

    A grand challenge in material science is to understand the correlation between intrinsic properties and defect dynamics. Radiation tolerant materials are in great demand for safe operation and advancement of nuclear and aerospace systems. Unlike traditional approaches that rely on microstructural and nanoscale features to mitigate radiation damage, this study demonstrates enhancement of radiation tolerance with the suppression of void formation by two orders magnitude at elevated temperatures in equiatomic single-phase concentrated solid solution alloys, and more importantly, reveals its controlling mechanism through a detailed analysis of the depth distribution of defect clusters and an atomistic computer simulation. The enhanced swelling resistance is attributed to the tailored interstitial defect cluster motion in the alloys from a long-range one-dimensional mode to a short-range three-dimensional mode, which leads to enhanced point defect recombination. Finally, the results suggest design criteria for next generation radiation tolerant structural alloys.

  11. Enhancing radiation tolerance by controlling defect mobility and migration pathways in multicomponent single-phase alloys

    NASA Astrophysics Data System (ADS)

    Lu, Chenyang; Niu, Liangliang; Chen, Nanjun; Jin, Ke; Yang, Taini; Xiu, Pengyuan; Zhang, Yanwen; Gao, Fei; Bei, Hongbin; Shi, Shi; He, Mo-Rigen; Robertson, Ian M.; Weber, William J.; Wang, Lumin

    2016-12-01

    A grand challenge in material science is to understand the correlation between intrinsic properties and defect dynamics. Radiation tolerant materials are in great demand for safe operation and advancement of nuclear and aerospace systems. Unlike traditional approaches that rely on microstructural and nanoscale features to mitigate radiation damage, this study demonstrates enhancement of radiation tolerance with the suppression of void formation by two orders magnitude at elevated temperatures in equiatomic single-phase concentrated solid solution alloys, and more importantly, reveals its controlling mechanism through a detailed analysis of the depth distribution of defect clusters and an atomistic computer simulation. The enhanced swelling resistance is attributed to the tailored interstitial defect cluster motion in the alloys from a long-range one-dimensional mode to a short-range three-dimensional mode, which leads to enhanced point defect recombination. The results suggest design criteria for next generation radiation tolerant structural alloys.

  12. Surface-enhanced Raman spectroscopy of dyes: from single molecules to the artists' canvas.

    PubMed

    Wustholz, Kristin L; Brosseau, Christa L; Casadio, Francesca; Van Duyne, Richard P

    2009-09-14

    This perspective presents recent surface-enhanced Raman spectroscopy (SERS) studies of dyes, with applications to the fields of single-molecule spectroscopy and art conservation. First we describe the development and outlook of single-molecule SERS (SMSERS). Rather than providing an exhaustive review of the literature, SMSERS experiments that we consider essential for its future development are emphasized. Shifting from single-molecule to ensemble-averaged experiments, we describe recent efforts toward SERS analysis of colorants in precious artworks. Our intention is to illustrate through these examples that the forward development of SERS is dependent upon both fundamental (e.g., SMSERS) and applied (e.g., on-the-specimen SERS of historical art objects) investigations and that the future of SERS is very bright indeed.

  13. 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

  14. Single-Dose Lignocaine-Based Blood Cardioplegia in Single Valve Replacement Patients.

    PubMed

    Ramani, Jaydip; Malhotra, Amber; Wadhwa, Vivek; Sharma, Pranav; Garg, Pankaj; Tarsaria, Malkesh; Pandya, Himani

    2017-01-01

    Myocardial protection is the most important in cardiac surgery. We compared our modified single-dose long-acting lignocaine-based blood cardioplegia with short-acting St Thomas 1 blood cardioplegia in patients undergoing single valve replacement. A total of 110 patients who underwent single (aortic or mitral) valve replacement surgery were enrolled. Patients were divided in two groups based on the cardioplegia solution used. In group 1 (56 patients), long-acting lignocaine based-blood cardioplegia solution was administered as a single dose while in group 2 (54 patients), standard St Thomas IB (short-acting blood-based cardioplegia solution) was administered and repeated every 20 minutes. All the patients were compared for preoperative baseline parameters, intraoperative and all the postoperative parameters. We did not find any statistically significant difference in preoperative baseline parameters. Cardiopulmonary bypass time were 73.8±16.5 and 76.4±16.9 minutes (P=0.43) and cross clamp time were 58.9±10.3 and 66.3±11.2 minutes (P=0.23) in group 1 and group 2, respectively. Mean of maximum inotrope score was 6.3±2.52 and 6.1±2.13 (P=0.65) in group 1 and group 2, respectively. We also did not find any statistically significant difference in creatine-phosphokinase-MB (CPK-MB), Troponin-I levels, lactate level and cardiac functions postoperatively. This study proves the safety and efficacy of long-acting lignocaine-based single-dose blood cardioplegia compared to the standard short-acting multi-dose blood cardioplegia in patients requiring the single valve replacement. Further studies need to be undertaken to establish this non-inferiority in situations of complex cardiac procedures especially in compromised patients.

  15. Oblivious transfer based on single-qubit rotations

    NASA Astrophysics Data System (ADS)

    Rodrigues, João; Mateus, Paulo; Paunković, Nikola; Souto, André

    2017-05-01

    We present a bit-string quantum oblivious transfer protocol based on single-qubit rotations. Our protocol is built upon a previously proposed quantum public-key protocol and its practical security relies on the laws of Quantum Mechanics. Practical security is reflected in the fact that, due to technological limitations, the receiver (Bob) of the transferred bit-string is restricted to performing only ‘few-qubit’ coherent measurements. We also present a single-bit oblivious transfer based on the proposed bit-string protocol. The protocol can be implemented with current technology based on optics.

  16. 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.

  17. Experimental synchronization of single-transistor-based chaotic circuits.

    PubMed

    Fortuna, Luigi; Frasca, Mattia

    2007-12-01

    This work deals with nonautonomous chaotic circuits and, in particular, with the experimental characterization of the synchronization properties of two simple nonautonomous circuits. Two single-transistor chaotic circuits, which are among the simplest chaotic oscillators, are investigated. We studied synchronization of these circuits and found that the most appropriate technique to synchronize two single-transistor chaotic circuits is that based on the design of an inverse circuit.

  18. Separation of single-base sequential isomers of single-stranded DNA by capillary electrophoresis and its application in the discrimination of single-base DNA mutations.

    PubMed

    Sakurai, Takao; Hoshino, Hitoshi; Takahashi, Toru

    2017-08-01

    Separation of single-base substitution sequential DNA isomers remains one of the most challenging tasks in DNA separation by capillary electrophoresis. We developed a simple, versatile capillary electrophoresis technique for the separation of single-base sequential isomers of DNA having the same chain length. This technique is based on charge differences resulting from the different protonation (acid dissociation) properties of the four DNA bases. A mixture of 13 single-base sequential isomers of 12-mer single-stranded DNA was separated by using an electrophoretic buffer solution containing 20 mM phosphoric acid (pH 2.0) and 8 M urea. We demonstrated that our method could separate all possible mutation patterns under identical experimental conditions. In addition, application of our method to the separation of the polymerase chain reaction product of a 68-mer gene fragment and its single-base isomers indicates that in combination with the appropriate genomic DNA extraction techniques, the method can detect single-base gene mutations. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Speech enhancement based on nonlinear models using particle filters.

    PubMed

    Mustière, Frédéric; Bolić, Miodrag; Bouchard, Martin

    2009-12-01

    Motivated by the reportedly strong performance of particle filters (PFs) for noise reduction on essentially linear speech production models, and the mounting evidence that the introduction of nonlinearities can lead to a refined speech model, this paper presents a study of PF solutions to the problem of speech enhancement in the context of nonlinear, neural-type speech models. Several variations of a global model are presented (single/multiple neurons; bias/no bias), and corresponding PF solutions are derived. Different importance functions are given when beneficial, Rao-Blackwellization is proposed when possible, and dual/nondual versions of each algorithms are presented. The method shown can handle both white and colored noise. Using a variety of speech and noise signals and different objective quality measures, the performance of these algorithms are evaluated against other PF solutions running on linear models, as well as some traditional enhancement algorithms. A certain hierarchy in performance is established between each algorithm in the paper. Depending on the experimental conditions, the best-performing algorithms are a classical Rao-Blackwellized particle filter (RBPF) running on a linear model, and a proposed PF employing a nondual, nonlinear model with multiple neurons and no biases. With consistence, the neural-network-based PF outperforms RBPF at low signal-to-noise ratio (SNR).

  20. Enhanced Telecom Emission from Single Group-IV Quantum Dots by Precise CMOS-Compatible Positioning in Photonic Crystal Cavities

    PubMed Central

    2017-01-01

    Efficient coupling to integrated high-quality-factor cavities is crucial for the employment of germanium quantum dot (QD) emitters in future monolithic silicon-based optoelectronic platforms. We report on strongly enhanced emission from single Ge QDs into L3 photonic crystal resonator (PCR) modes based on precise positioning of these dots at the maximum of the respective mode field energy density. Perfect site control of Ge QDs grown on prepatterned silicon-on-insulator substrates was exploited to fabricate in one processing run almost 300 PCRs containing single QDs in systematically varying positions within the cavities. Extensive photoluminescence studies on this cavity chip enable a direct evaluation of the position-dependent coupling efficiency between single dots and selected cavity modes. The experimental results demonstrate the great potential of the approach allowing CMOS-compatible parallel fabrication of arrays of spatially matched dot/cavity systems for group-IV-based data transfer or quantum optical systems in the telecom regime. PMID:28345012

  1. Surface-enhanced photocycle studied in a single photoreceptor protein molecule

    NASA Astrophysics Data System (ADS)

    Kalkan, Kaan; Xie, Aihua

    2009-03-01

    Photoactive yellow protein (PYP) functions as a blue light sensor for bacterial vision (phototaxis). The photocycle of PYP is initiated by the absorption of a blue photon (absorption peak at 446 nm) by its para-coumaric acid (pCA) chromophore. The photon energy is stored in the pCA through photoisomerization which is subsequently transferred to the rest of the protein through a series of conformational states, finally leading to its partial unfolding (signaling). The present work captures the distinct conformational changes of PYP at the single molecule level, during the execution of its photocycle. In particular, the present work employs surface-enhanced Raman scattering (SERS) active substrates and non-resonant excitation at 514 nm. As we confirm with regular Raman spectroscopy, the photocycle of PYP cannot be excited under 514 nm irradiation. On the contrary, 514 nm photons can excite the photocycle when PYP is adsorbed on silver, as we evidence from single molecule as well as ensemble-averaged SERS. In this case, the optical absorption of PYP shows a dramatic broadening (full width at half maximum shifting from 0.4 to 0.9 eV) such that electronic excitation can occur significantly at 514 nm. Therefore, the origin of the observed ``surface-enhanced photocycle'' is understood to be of the same as ``chemical enhancement'' in SERS in view of the ``adsorbate-induced resonance states'' model (Persson, 1993).

  2. 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.

  3. Enhancing yields of low and single copy number plasmid DNAs from Escherichia coli cells.

    PubMed

    Wood, Whitney N; Smith, Kyle D; Ream, Jennifer A; Kevin Lewis, L

    2017-02-01

    Many plasmids used for gene cloning and heterologous protein expression in Escherichia coli cells are low copy number or single copy number plasmids. The extraction of these types of plasmids from small bacterial cell cultures produces low DNA yields. In this study, we have quantitated yields of low copy and single copy number plasmid DNAs after growth of cells in four widely used broths (SB, SOC, TB, and 2xYT) and compared results to those obtained with LB, the most common E. coli cell growth medium. TB (terrific broth) consistently generated the greatest amount of plasmid DNA, in agreement with its ability to produce higher cell titers. The superiority of TB was primarily due to its high levels of yeast extract (24g/L) and was independent of glycerol, a unique component of this broth. Interestingly, simply preparing LB with similarly high levels of yeast extract (LB24 broth) resulted in plasmid yields that were equivalent to those of TB. By contrast, increasing ampicillin concentration to enhance plasmid retention did not improve plasmid DNA recovery. These experiments demonstrate that yields of low and single copy number plasmid DNAs from minipreps can be strongly enhanced using simple and inexpensive media.

  4. 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

  5. Alcohol sensor based on single-mode-multimode-single-mode fiber structure

    NASA Astrophysics Data System (ADS)

    Mefina Yulias, R.; Hatta, A. M.; Sekartedjo, Sekartedjo

    2016-11-01

    Alcohol sensor based on Single-mode -Multimode-Single-mode (SMS) fiber structure is being proposed to sense alcohol concentration in alcohol-water mixtures. This proposed sensor uses refractive index sensing as its sensing principle. Fabricated SMS fiber structure had 40 m of multimode length. With power input -6 dBm and wavelength 1550 nm, the proposed sensor showed good response with sensitivity 1,983 dB per % v/v with measurement range 05 % v/v and measurement span 0,5% v/v.

  6. Graphene-Based Josephson-Junction Single-Photon Detector

    NASA Astrophysics Data System (ADS)

    Walsh, Evan D.; Efetov, Dmitri K.; Lee, Gil-Ho; Heuck, Mikkel; Crossno, Jesse; Ohki, Thomas A.; Kim, Philip; Englund, Dirk; Fong, Kin Chung

    2017-08-01

    We propose to use graphene-based Josephson junctions (GJJs) to detect single photons in a wide electromagnetic spectrum from visible to radio frequencies. Our approach takes advantage of the exceptionally low electronic heat capacity of monolayer graphene and its constricted thermal conductance to its phonon degrees of freedom. Such a system could provide high-sensitivity photon detection required for research areas including quantum information processing and radio astronomy. As an example, we present our device concepts for GJJ single-photon detectors in both the microwave and infrared regimes. The dark count rate and intrinsic quantum efficiency are computed based on parameters from a measured GJJ, demonstrating feasibility within existing technologies.

  7. Genetic interaction mapping with microfluidic-based single cell sequencing.

    PubMed

    Haliburton, John R; Shao, Wenjun; Deutschbauer, Adam; Arkin, Adam; Abate, Adam R

    2017-01-01

    Genetic interaction mapping is useful for understanding the molecular basis of cellular decision making, but elucidating interactions genome-wide is challenging due to the massive number of gene combinations that must be tested. Here, we demonstrate a simple approach to thoroughly map genetic interactions in bacteria using microfluidic-based single cell sequencing. Using single cell PCR in droplets, we link distinct genetic information into single DNA sequences that can be decoded by next generation sequencing. Our approach is scalable and theoretically enables the pooling of entire interaction libraries to interrogate multiple pairwise genetic interactions in a single culture. The speed, ease, and low-cost of our approach makes genetic interaction mapping viable for routine characterization, allowing the interaction network to be used as a universal read out for a variety of biology experiments, and for the elucidation of interaction networks in non-model organisms.

  8. Genetic interaction mapping with microfluidic-based single cell sequencing

    PubMed Central

    Haliburton, John R.; Shao, Wenjun; Deutschbauer, Adam; Arkin, Adam; Abate, Adam R.

    2017-01-01

    Genetic interaction mapping is useful for understanding the molecular basis of cellular decision making, but elucidating interactions genome-wide is challenging due to the massive number of gene combinations that must be tested. Here, we demonstrate a simple approach to thoroughly map genetic interactions in bacteria using microfluidic-based single cell sequencing. Using single cell PCR in droplets, we link distinct genetic information into single DNA sequences that can be decoded by next generation sequencing. Our approach is scalable and theoretically enables the pooling of entire interaction libraries to interrogate multiple pairwise genetic interactions in a single culture. The speed, ease, and low-cost of our approach makes genetic interaction mapping viable for routine characterization, allowing the interaction network to be used as a universal read out for a variety of biology experiments, and for the elucidation of interaction networks in non-model organisms. PMID:28170417

  9. 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.

  10. ABCG2 regulatory single-nucleotide polymorphisms alter in-vivo enhancer activity and expression.

    PubMed

    Eclov, Rachel J; Kim, Mee J; Chhibber, Aparna; Smith, Robin P; Ahituv, Nadav; Kroetz, Deanna L

    2017-09-18

    The expression and activity of the breast cancer resistance protein (ABCG2) contributes toward the pharmacokinetics of endogenous and xenobiotic substrates. The effect of genetic variation on the activity of cis-regulatory elements and nuclear response elements in the ABCG2 locus and their contribution toward ABCG2 expression have not been investigated systematically. In this study, the effect of genetic variation on the in-vitro and in-vivo enhancer activity of six previously identified liver enhancers in the ABCG2 locus was examined. Reference and variant liver enhancers were tested for their ability to alter luciferase activity in vitro in HepG2 and HEK293T cell lines and in vivo using a hydrodynamic tail vein assay. Positive in-vivo single-nucleotide polymorphisms (SNPs) were tested for association with gene expression and for altered protein binding in electrophoretic mobility shift assays. Multiple SNPs were found to alter enhancer activity in vitro. Four of these variants (rs9999111, rs12508471, ABCG2RE1*2, and rs149713212) decreased and one (rs2725263) increased enhancer activity in vivo. In addition, rs9999111 and rs12508471 were associated with ABCG2 expression in lymphoblastoid cell lines, lymphocytes, and T cells, and showed increased HepG2 nuclear protein binding. This study identifies SNPs within regulatory regions of the ABCG2 locus that alter enhancer activity in vitro and in vivo. Several of these SNPs correlate with tissue-specific ABCG2 expression and alter DNA/protein binding. These SNPs could contribute toward reported tissue-specific variability in ABCG2 expression and may influence the correlation between ABCG2 expression and disease risk or the pharmacokinetics and pharmacodynamics of breast cancer resistance protein substrates.

  11. Enhanced electrocaloric cooling in ferroelectric single crystals by electric field reversal

    NASA Astrophysics Data System (ADS)

    Ma, Yang-Bin; Novak, Nikola; Koruza, Jurij; Yang, Tongqing; Albe, Karsten; Xu, Bai-Xiang

    2016-09-01

    An improved thermodynamic cycle is validated in ferroelectric single crystals, where the cooling effect of an electrocaloric refrigerant is enhanced by applying a reversed electric field. In contrast to the conventional adiabatic heating or cooling by on-off cycles of the external electric field, applying a reversed field is significantly improving the cooling efficiency, since the variation in configurational entropy is increased. By comparing results from computer simulations using Monte Carlo algorithms and experiments using direct electrocaloric measurements, we show that the electrocaloric cooling efficiency can be enhanced by more than 20% in standard ferroelectrics and also relaxor ferroelectrics, like Pb (Mg1 /3 /Nb2 /3)0.71Ti0.29O3 .

  12. 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.

  13. Enhancing the Elasticity of Ultrathin Single-Wall Carbon Nanotube Films with Colloidal Nanocrystals.

    PubMed

    Alzaid, Meshal; Roth, Joseph; Wang, Yuezhou; Almutairi, Eid; Brown, Samuel L; Dumitrică, Traian; Hobbie, Erik K

    2017-08-15

    Thin bilayers of contrasting nanomaterials are ubiquitous in solution-processed electronic devices and have potential relevance to a number of applications in flexible electronics. Motivated by recent mesoscopic simulations demonstrating synergistic mechanical interactions between thin films of single-wall carbon nanotubes (SWCNTs) and spherical nanocrystal (NC) inclusions, we use a thin-film wrinkling approach to query the compressive mechanics of hybrid nanotube/nanocrystal coatings adhered to soft polymer substrates. Our results show an almost 2-fold enhancement in the Young modulus of a sufficiently thin SWCNT film associated with the presence of a thin interpenetrating overlayer of semiconductor NCs. Mesoscopic distinct-element method simulations further support the experimental findings by showing that the additional noncovalent interfaces introduced by nanocrystals enhance the modulus of the SWCNT network and hinder network wrinkling.

  14. Enhancing radiation tolerance by controlling defect mobility and migration pathways in multicomponent single-phase alloys

    DOE PAGES

    Lu, Chenyang; Niu, Liangliang; Chen, Nanjun; ...

    2016-12-15

    A grand challenge in material science is to understand the correlation between intrinsic properties and defect dynamics. Radiation tolerant materials are in great demand for safe operation and advancement of nuclear and aerospace systems. Unlike traditional approaches that rely on microstructural and nanoscale features to mitigate radiation damage, this study demonstrates enhancement of radiation tolerance with the suppression of void formation by two orders magnitude at elevated temperatures in equiatomic single-phase concentrated solid solution alloys, and more importantly, reveals its controlling mechanism through a detailed analysis of the depth distribution of defect clusters and an atomistic computer simulation. The enhancedmore » swelling resistance is attributed to the tailored interstitial defect cluster motion in the alloys from a long-range one-dimensional mode to a short-range three-dimensional mode, which leads to enhanced point defect recombination. Finally, the results suggest design criteria for next generation radiation tolerant structural alloys.« less

  15. 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

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

    PubMed

    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.

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

    PubMed

    McAndrew, Calum F; Baxendale, Mark

    2013-08-02

    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.

  18. 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.…

  19. Quantum-interference-enhanced thermoelectricity in single molecules and molecular films

    NASA Astrophysics Data System (ADS)

    Lambert, Colin J.; Sadeghi, Hatef; Al-Galiby, Qusiy H.

    2016-12-01

    We provide a brief overview of recent measurements and predictions of thermoelectric properties of single-molecules and porous nanoribbons and discuss some principles underpinning strategies for enhancing their thermoelectric performance. The latter include (a) taking advantage of steep slopes in the electron transmission coefficient T (E), (b) creating structures with delta-function-like transmission coefficients and (c) utilising step-like features in T (E). To achieve high performance, we suggest that the latter may be the most fruitful, since it is less susceptible to inhomogeneous broadening. For the purpose of extrapolating thermoelectric properties of single or few molecules to monolayer molecular films, we also discuss the relevance of the conductance-weighted average Seebeck coefficient. xml:lang="fr"

  20. 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).

  1. 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.

  2. Surface-enhanced Raman signal for terbium single-molecule magnets grafted on graphene.

    PubMed

    Lopes, Manuel; Candini, Andrea; Urdampilleta, Matias; Reserbat-Plantey, Antoine; Bellini, Valerio; Klyatskaya, Svetlana; Marty, Laëtitia; Ruben, Mario; Affronte, Marco; Wernsdorfer, Wolfgang; Bendiab, Nedjma

    2010-12-28

    We report the preparation and characterization of monolayer graphene decorated with functionalized single-molecule magnets (SMMs). The grafting ligands provide a homogeneous and selective deposition on graphene. The grafting is characterized by combined Raman microspectroscopy, atomic force microscopy (AFM), and electron transport measurements. We observe a surface-enhanced Raman signal that allowed us to study the grafting down to the limit of a few isolated molecules. The weak interaction through charge transfer is in agreement with ab initio DFT calculations. Our results indicate that both molecules and graphene are essentially intact and the interaction is driven by van der Waals forces.

  3. An evaluation of the perceptual quality of phase-aware single-channel speech enhancement.

    PubMed

    Krawczyk-Becker, Martin; Gerkmann, Timo

    2016-10-01

    For the enhancement of single-channel speech corrupted by acoustic noise, recently short-time Fourier transform domain clean speech estimators were proposed that incorporate prior information about the clean speech spectral phase. Instrumental measures predict quality improvements for the phase-aware estimators over their conventional phase-blind counterparts. In this letter, these predictions are verified by means of listening experiments. The phase-aware amplitude estimator on average achieves a stronger noise reduction and is significantly preferred over its phase-blind counterpart in a pairwise comparison even if the clean spectral phase is estimated blindly on the noisy signal.

  4. 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.

  5. 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

  6. 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.

  7. 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…

  8. 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…

  9. Enhancing the scientific credibility of single-case intervention research: randomization to the rescue.

    PubMed

    Kratochwill, Thomas R; Levin, Joel R

    2010-06-01

    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 multiple-participant experimental designs, there are procedures that can be adopted to create a randomized experiment in this class of experimental design. Our two major purposes in writing this article were (a) to review the various types of single-case design that have been and can be used in psychological and educational intervention research and (b) to incorporate randomized experimental schemes into these designs, thereby improving them so that investigators can draw more valid conclusions from their research. For each traditional single-case design type reviewed, we provide illustrations of how various forms of randomization can be introduced into the basic design structure. We conclude by recommending that traditional single-case intervention designs be transformed into more scientifically credible randomized single-case intervention designs whenever the research conditions under consideration permit.

  10. 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.

  11. 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.

  12. A novel permalloy based magnetic single cell micro array.

    PubMed

    Liu, William; Dechev, Nikolai; Foulds, Ian G; Burke, Robert; Parameswaran, Ash; Park, Edward J

    2009-08-21

    Devices capable of automatically aligning cells onto geometrical arrays are of great interest to biomedical researchers. Such devices can facilitate the study of numerous cells while the cells remain physically separated from one another. In this way, cell arrays reduce cell-to-cell interactions while the cells are all subjected to common stimuli, which allows individual cell behaviour to be revealed. The use of arrays allows for the parallel analysis of single cells, facilitates data logging, and opens the door to the use of automated machine-based single cell analysis techniques. A novel permalloy based magnetic single cell micro array (MSCMA) is presented in this paper. The MSCMA creates an array of magnetic traps by generating magnetic flux density peaks at predefined locations. When using cells labelled with immunomagnetic labels, the cells will interact with the magnetic fields, and can be captured at the magnetic trap sites. Prototypes of the MSCMA have been successfully fabricated and tested using both fixed and live Jurkat cells (10 microm average diameter) that were labelled. The prototypes performed as predicted during experimental trials. The experimental results show that the MSCMA can randomly array up to 136 single cells per square mm. The results also show that the number of single cells captured is a function of the trap site density of the MSCMA design and the cell density in the fluid sample.

  13. Metamaterial-based single pixel imaging system (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Padilla, Willie; Watts, Claire M.; Nadell, Christian; Montoya, John A.; Krishna, Sanjay

    2015-09-01

    Single pixel cameras are useful imaging devices where it is difficult or infeasible to fashion focal plan arrays. For example in the Far Infrared (FIR) it is difficult to perform imaging by conventional detector arrays, owing to the cost and size of such an array. The typical single pixel camera uses a spatial light modulator (SLM) - placed in the conjugate image plane - and is used to sample various portions of the image. The spatially modulated light emerging from the SLM is then sent to a single detector where the light is condensed with suitable optics for detection. Conventional SLMs are either based on liquid crystals or digital mirror devices. As such these devices are limited in modulation speeds of order 30 kHz. Further there is little control over the type of light that is modulated. We present metamaterial based spatial light modulators which provide the ability to digitally encode images - with various measurement matrix coefficients - thus permitting high speed and fidelity imaging capability. In particular we use the Hadamard matrix and related S-matrix to encode images for single pixel imaging. Metamaterials thus permit imaging in regimes of the electromagnetic spectrum where conventional SLMs are not available. Additionally, metamaterials offer several salient features that are not available with commercial SLMs. For example, metamaterials may be used to enable hyperspectral, polarimetric, and phase sensitive imaging. We present the theory and experimental results of single pixel imaging with digital metamaterials in the far infrared and highlight the future of this exciting field.

  14. Crossbridge properties during force enhancement by slow stretching in single intact frog muscle fibres

    PubMed Central

    Colombini, Barbara; Nocella, Marta; Benelli, Giulia; Cecchi, Giovanni; Bagni, Maria Angela

    2007-01-01

    The mechanism of force enhancement during lengthening was investigated on single frog muscle fibres by using fast stretches to measure the rupture tension of the crossbridge ensemble. Fast stretches were applied to one end of the activated fibre and force responses were measured at the other. Sarcomere length was measured by a striation follower device. Fast stretching induced a linear increase of tension that reached a peak and fell before the end of the stretch indicating that a sudden increase of fibre compliance occurred due to forced crossbridge detachment induced by the fast loading. The peak tension (critical tension, Pc) and the sarcomere length needed to reach Pc (critical length, Lc) were measured at various tensions during the isometric tetanus rise and during force enhancement by slow lengthening. The data showed that Pc was proportional to the tension generated by the fibre under both isometric and slow lengthening conditions. However, for a given tension increase, Pc was 6.5 times greater during isometric than during lengthening conditions. Isometric critical length was 13.04 ± 0.17 nm per half-sarcomere (nm hs−1) independently of tension. During slow lengthening critical length fell as the force enhancement increased. For 90% enhancement, Lc reduced to 8.19 ± 0.039 nm hs−1. Assuming that the rupture force of the individual crossbridge is constant, these data indicate that the increase of crossbridge number during lengthening accounts for only 15.4% of the total force enhancement. The remaining 84.6% is accounted for by the increased mean strain of the crossbridges. PMID:17932153

  15. Polarization manipulation in single refractive prism based holography lithography

    NASA Astrophysics Data System (ADS)

    Xiong, Wenjie; Xu, Yi; Xiao, Yujian; Lv, Xiaoxu; Wu, Lijun

    2015-01-01

    We propose theoretically and demonstrate experimentally a simple but effective strategy for polarization manipulation in single refractive prism based holographic lithography. By tuning the polarization of a single laser beam, we can obtain the pill shape interference pattern with a high-contrast where a complex optical setup and multiple polarizers are needed in the conventional holography lithography. Fabrication of pill shape two-dimensional polymer photonic crystals using one beam and one shoot holography lithography is shown as an example to support our theoretical results. This integrated polarization manipulation technique can release the crucial stability restrictions imposed on the multiple beams holography lithography.

  16. Is Tb3+ fluorescence enhancement only due to binding to single stranded polynucleotides.

    PubMed Central

    Haertlé, T; Augustyniak, J; Guschlbauer, W

    1981-01-01

    Enhancement of Tb3+ fluorescence upon binding to double-stranded ribo- and deoxyribo-duplexes was investigated. It was observed that certain double stranded ribopolynucleotides completely quenched the Tb3+ fluorescence and others did not. It is concluded that the nature of the base in the duplex is critical for this enhancement. - Polydeoxyduplexes also showed enhancement of Tb3+ fluorescence, but much higher terbium concentrations were necessary to obtain similar fluorescence signals, indicative of unspecific effects. CD spectra evidence considerable conformational changes of these duplexes, in particular poly(dG-C) . poly(dG-C( which assumes the Z-form in 0.1 nM Tb3+. PMID:7312634

  17. Contrast Enhancement Based on Intrinsic Image Decomposition.

    PubMed

    Yue, Huanjing; Yang, Jingyu; Sun, Xiaoyan; Wu, Feng; Hou, Chunping

    2017-05-10

    In this paper, we propose to introduce intrinsic image decomposition priors into decomposition models for contrast enhancement. Since image decomposition is a highly ill-posed problem, we introduce constraints on both reflectance and illumination layers to yield a highly reliable solution. We regularize the reflectance layer to be piecewise constant by introducing a weighted `1 norm constraint on neighboring pixels according to the color similarity, so that the decomposed reflectance would not be affected much by the illumination information. The illumination layer is regularized by a piecewise smoothness constraint. The proposed model is effectively solved by the Split Bregman algorithm. Then, by adjusting the illumination layer, we obtain the enhancement result. To avoid potential color artifacts introduced by illumination adjusting and reduce computing complexity, the proposed decomposition model is performed on the value channel in HSV space. Experiment results demonstrate that the proposed method performs well for a wide variety of images, and achieves better or comparable subjective and objective quality compared with state-of-the-art methods.

  18. Single qubit operations with base squeezed coherent states

    NASA Astrophysics Data System (ADS)

    Podoshvedov, Sergey A.

    2013-03-01

    In quantum computing with base either coherent or squeezed coherent states, information is encoded into coherent states with opposite amplitudes. To exploit the base states in quantum computation, we need arbitrary qubit rotations plus a two-qubit gate such as controlled-Z gate to simulate any multiqubit unitary transformations. We develop an approach to realize single qubit operations with the base squeezed coherent states. The optical setup requires a resource of the base squeezed coherent states, unbalanced beam splitter whose transmittance tends to unity and photon counters in auxiliary modes. A successful two-photon subtraction from transmitted beam is heralded by two-photon click in auxiliary modes where tiny part of the initial beam is detected. The thrust of the method is that it achieves a high fidelity without photodetectors with a high efficiency or a single-photon resolution. We observe that there is wide diapason of values of the parameters that provide performance of single qubit operations with the base states. The problem is resolved in Wigner representation to take into account imperfections of the optical devices.

  19. Aerosol optical properties measurement by recently developed cavity-enhanced aerosol single scattering albedometer

    NASA Astrophysics Data System (ADS)

    Zhao, Weixiong; Xu, Xuezhe; Zhang, Qilei; Fang, Bo; Qian, Xiaodong; Chen, Weidong; Gao, Xiaoming; Zhang, Weijun

    2015-04-01

    Development of appropriate and well-adapted measurement technologies for real-time in-situ measurement of aerosol optical properties is an important step towards a more accurate and quantitative understanding of aerosol impacts on climate and the environment. Aerosol single scattering albedo (SSA, ω), the ratio between the scattering (αscat) and extinction (αext) coefficients, is an important optical parameter that governs the relative strength of the aerosol scattering and absorption capacity. Since the aerosol extinction coefficient is the sum of the absorption and scattering coefficients, a commonly used method for the determination of SSA is to separately measure two of the three optical parameters - absorption, scattering and extinction coefficients - with different instruments. However, as this method involves still different instruments for separate measurements of extinction and absorption coefficients under different sampling conditions, it might cause potential errors in the determination of SSA value, because aerosol optical properties are very sensitive to the sampling conditions such as temperature and relative humidity (RH). In this paper, we report on the development of a cavity-enhanced aerosol single scattering albedometer incorporating incoherent broad-band cavity-enhanced spectroscopy (IBBCEAS) and an integrating sphere (IS) for direct in-situ measurement of aerosol scattering and extinction coefficients on the exact same sample volume. The cavity-enhanced albedometer holds great promise for high-sensitivity and high-precision measurement of ambient aerosol scattering and extinction coefficients (hence absorption coefficient and SSA determination) and for absorbing trace gas concentration. In addition, simultaneous measurements of aerosol scattering and extinction coefficients enable a potential application for the retrieval of particle number size distribution and for faster retrieval of aerosols' complex RI. The albedometer was deployed to

  20. 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.

  1. Wafer-scale metasurface for total power absorption, local field enhancement and single molecule Raman spectroscopy.

    PubMed

    Wang, Dongxing; Zhu, Wenqi; Best, Michael D; Camden, Jon P; Crozier, Kenneth B

    2013-10-04

    The ability to detect molecules at low concentrations is highly desired for applications that range from basic science to healthcare. Considerable interest also exists for ultrathin materials with high optical absorption, e.g. for microbolometers and thermal emitters. Metal nanostructures present opportunities to achieve both purposes. Metal nanoparticles can generate gigantic field enhancements, sufficient for the Raman spectroscopy of single molecules. Thin layers containing metal nanostructures ("metasurfaces") can achieve near-total power absorption at visible and near-infrared wavelengths. Thus far, however, both aims (i.e. single molecule Raman and total power absorption) have only been achieved using metal nanostructures produced by techniques (high resolution lithography or colloidal synthesis) that are complex and/or difficult to implement over large areas. Here, we demonstrate a metasurface that achieves the near-perfect absorption of visible-wavelength light and enables the Raman spectroscopy of single molecules. Our metasurface is fabricated using thin film depositions, and is of unprecedented (wafer-scale) extent.

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

    SciTech Connect

    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-crystal 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.

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

    DOE PAGES

    Muhrer, Guenter; Schönfeldt, Troels; Iverson, Erik B.; ...

    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

  4. Silver Embedded Nanomesas as Enhanced Single Quantum Dot Emitters in the Telecommunication C Band

    NASA Astrophysics Data System (ADS)

    Huh, Jae-Hoon; Hermannstädter, Claus; Akahane, Kouichi; Jahan, Nahid A.; Sasaki, Masahide; Suemune, Ikuo

    2012-06-01

    We use high-density InAs quantum dots, which were grown by molecular beam epitaxy on InP(311)B substrates, as photon sources in the telecommunication C band at approximately 1.55 µm. To select a small numbers of dots, we fabricate sub-micrometer sized mesas by electron beam lithography and reactive ion etching. The benefit of using high-density quantum dot samples is that at least one optically active quantum dot can be expected in every single mesa. We show that the etching rate and resulting mesa shape of the In0.53Al0.22Ga0.25As epitaxial layer can be varied with the chamber pressure during the etching process. Furthermore, under constant pressure and with increasing etching time, the sequential etching of the epitaxial layer and the underneath substrate leads to a significant modification in the mesa shape, too. We demonstrate that the isolation of a small number of quantum dots within one mesa results in the appearance of single quantum dot emission with a narrow line width and minimal spectral overlap between different emission lines. We moreover present significant enhancement of the luminescence collected from single dots in silver-embedded nanomesas when compared with as-etched mesas.

  5. 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.

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

    SciTech Connect

    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-crystal 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.

  7. An enhanced single-channel algorithm for retrieving land surface temperature from Landsat series data

    NASA Astrophysics Data System (ADS)

    Wang, Mengmeng; Zhang, Zhaoming; He, Guojin; Wang, Guizhou; Long, Tengfei; Peng, Yan

    2016-10-01

    Land surface temperature (LST) is a critical parameter in the physics of Earth surface processes and is required for many applications related to ecology and environment. Landsat series satellites have provided more than 30 years of thermal information at medium spatial resolution. This paper proposes an enhanced single-channel algorithm (SCen) for retrieving LST from Landsat series data (Landsat 4 to Landsat 8). The SCen algorithm includes three atmospheric functions (AFs), and the latitude and acquisition month of Landsat image were added to the AF models to improve LST retrieval. Performance of the SCen algorithm was assessed with both simulated and in situ data, and accuracy of three single-channel algorithms (including the monowindow algorithm developed by Qin et al., SCQin, and the generalized single-channel algorithm developed by Jiménez-Muñoz and Sobrino, SCJ&S) were compared. The accuracy assessments with simulated data had root-mean-square deviations (RMSDs) for the SCen, SCJ&S, and SCQin algorithms of 1.363 K, 1.858 K, and 2.509 K, respectively. Validation with in situ data showed RMSDs for the SCen and SCJ&S algorithms of 1.04 K and 1.49 K, respectively. It was concluded that the SCen algorithm is very operational, has good precision, and can be used to develop an LST product for Landsat series data.

  8. ELQ-300 prodrugs for enhanced delivery and single-dose cure of malaria.

    PubMed

    Miley, Galen P; Pou, Sovitj; Winter, Rolf; Nilsen, Aaron; Li, Yuexin; Kelly, Jane X; Stickles, Allison M; Mather, Michael W; Forquer, Isaac P; Pershing, April M; White, Karen; Shackleford, David; Saunders, Jessica; Chen, Gong; Ting, Li-Min; Kim, Kami; Zakharov, Lev N; Donini, Cristina; Burrows, Jeremy N; Vaidya, Akhil B; Charman, Susan A; Riscoe, Michael K

    2015-09-01

    ELQ-300 is a preclinical candidate that targets the liver and blood stages of Plasmodium falciparum, as well as the forms that are crucial to transmission of disease: gametocytes, zygotes, and ookinetes. A significant obstacle to the clinical development of ELQ-300 is related to its physicochemical properties. Its relatively poor aqueous solubility and high crystallinity limit absorption to the degree that only low blood concentrations can be achieved following oral dosing. While these low blood concentrations are sufficient for therapy, the levels are too low to establish an acceptable safety margin required by regulatory agencies for clinical development. One way to address the challenging physicochemical properties of ELQ-300 is through the development of prodrugs. Here, we profile ELQ-337, a bioreversible O-linked carbonate ester prodrug of the parent molecule. At the molar equivalent dose of 3 mg/kg of body weight, the delivery of ELQ-300 from ELQ-337 is enhanced by 3- to 4-fold, reaching a maximum concentration of drug in serum (C max) of 5.9 μM by 6 h after oral administration, and unlike ELQ-300 at any dose, ELQ-337 provides single-dose cures of patent malaria infections in mice at low-single-digit milligram per kilogram doses. Our findings show that the prodrug strategy represents a viable approach to overcome the physicochemical limitations of ELQ-300 to deliver the active drug to the bloodstream at concentrations sufficient for safety and toxicology studies, as well as achieving single-dose cures.

  9. Cavity-enhanced single photons from a quantum dot (Invited Paper)

    NASA Astrophysics Data System (ADS)

    Vuckovic, Jelena; Fattal, David; Englund, Dirk; Waks, Edo; Santori, Charles; Solomon, Glenn; Yamamoto, Yoshihisa

    2005-04-01

    Single-photon sources rarely emit two or more photons in the same pulse, compared to a Poisson-distributed source of the same intensity, and have numerous applications in quantum information science. The quality of such a source is evaluated based on three criteria: high efficiency, small multi-photon probability, and quantum indistinguishability. We have demonstrated a single-photon source based on a quantum dot in a micropost microcavity that exhibits a large Purcell factor together with a small multi-photon probability. For a quantum dot on resonance with the cavity, the spontaneous emission rate has been increased by a factor of five, while the probability to emit two or more photons in the same pulse has been reduced to 2% compared to a Poisson-distributed source of the same intensity. The indistinguishability of emitted single photons from one of our devices has been tested through a Hong-Ou-Mandel-type two-photon interference experiment; consecutive photons emitted from such a source have been largely indistinguishable, with a mean wave-packet overlap as large as 0.81. We have also designed and demonstrated two-dimensional photonic crystal GaAs cavities containing InAs quantum dots that exhibit much higher quality factors together with much smaller mode volumes than microposts, and therefore present an ideal platform for construction of single photon sources of even higher quality.

  10. Autofocusing system based on signal processing of single chip microprocessor

    NASA Astrophysics Data System (ADS)

    Xu, Xiangdong; Zeng, Chao; Li, Feng; Huang, GuiZao

    2002-09-01

    In this paper, an auto-focusing system based on Signal Processing of Single-chip Microprocessor is introduced to realize auto-focusing. The system can automatically get the distance information of the worktable and drive the step motor to reach the aim of auto-focusing. The auto-focusing system is loaded in the original CMOS-based measuring system. After the AV signals from CMOS image sensor pass through the analog filter, the single-chip microprocessor samples and processes them, then controls the lens to be in focus. As a result, this method can not only achieve all functions of focusing, but also avoid complicated calculations. The system is low power consuming, programming rapidly. Here we analyse the key technique of the system and the results of the experiments are given. It can be practical applied and the further perfection of algorithm and software will result in the system having more function.

  11. 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

    2016-07-12

    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.

  12. 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.

  13. Single-trial effective brain connectivity patterns enhance discriminability of mental imagery tasks

    NASA Astrophysics Data System (ADS)

    Rathee, Dheeraj; Cecotti, Hubert; Prasad, Girijesh

    2017-10-01

    Objective. The majority of the current approaches of connectivity based brain-computer interface (BCI) systems focus on distinguishing between different motor imagery (MI) tasks. Brain regions associated with MI are anatomically close to each other, hence these BCI systems suffer from low performances. Our objective is to introduce single-trial connectivity feature based BCI system for cognition imagery (CI) based tasks wherein the associated brain regions are located relatively far away as compared to those for MI. Approach. We implemented time-domain partial Granger causality (PGC) for the estimation of the connectivity features in a BCI setting. The proposed hypothesis has been verified with two publically available datasets involving MI and CI tasks. Main results. The results support the conclusion that connectivity based features can provide a better performance than a classical signal processing framework based on bandpass features coupled with spatial filtering for CI tasks, including word generation, subtraction, and spatial navigation. These results show for the first time that connectivity features can provide a reliable performance for imagery-based BCI system. Significance. We show that single-trial connectivity features for mixed imagery tasks (i.e. combination of CI and MI) can outperform the features obtained by current state-of-the-art method and hence can be successfully applied for BCI applications.

  14. How VASP enhances actin-based motility

    PubMed Central

    Samarin, Stanislav; Romero, Stéphane; Kocks, Christine; Didry, Dominique; Pantaloni, Dominique; Carlier, Marie-France

    2003-01-01

    The function of vasodilator-stimulated phosphoprotein (VASP) in motility is analyzed using a biomimetic motility assay in which ActA-coated microspheres propel themselves in a medium containing actin, the Arp2/3 complex, and three regulatory proteins in the absence or presence of VASP. Propulsion is linked to cycles of filament barbed end attachment-branching-detachment-growth in which the ActA-activated Arp2/3 complex incorporates at the junctions of branched filaments. VASP increases the velocity of beads. VASP increases branch spacing of filaments in the actin tail, as it does in lamellipodia in living cells. The effect of VASP on branch spacing of Arp2/3-induced branched actin arrays is opposed to the effect of capping proteins. However, VASP does not compete with capping proteins for binding barbed ends of actin filaments. VASP enhances branched actin polymerization only when ActA is immobilized on beads or on Listeria. VASP increases the rate of dissociation of the branch junction from immobilized ActA, which is the rate-limiting step in the catalytic cycle of site-directed filament branching. PMID:14557252

  15. Quantum Chemical Characterization of Single Molecule Magnets Based on Uranium.

    PubMed

    Spivak, Mariano; Vogiatzis, Konstantinos D; Cramer, Christopher J; Graaf, Coen de; Gagliardi, Laura

    2017-03-02

    Multiconfigurational electronic structure theory calculations including spin-orbit coupling effects were performed on four uranium-based single-molecule-magnets. Several quartet and doublet states were computed and the energy gaps between spin-orbit states were then used to determine magnetic susceptibility curves. Trends in experimental magnetic susceptibility curves were well reproduced by the calculations, and key factors affecting performance were identified.

  16. 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.

  17. 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…

  18. 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.

  19. Histological skin morphology enhancement base on molecular hyperspectral imaging technology.

    PubMed

    Li, Q; Sun, Z; Wang, Y; Liu, H; Guo, F; Zhu, J

    2014-08-01

    Most traditional skin histological analysis methods are based on the light microscopy images, which can only provide limited information and low contrast results for pathology evaluation. Molecular hyperspectral imaging technology can provide both spatial and spectral information of skin sections, which is a new method for histological skin analysis. The molecular hyperspectral imaging system was developed by coupling an acousto-optic tunable filters adapter to microscopy and the molecular hyperspectral images were analyzed by home-written software with image processing algorithms. Then, the histological structures in skin sections were investigated in several locations to evaluate the potential application of the molecular hyperspectral imaging technique to dermatology. Molecular hyperspectral images of skin sections were obtained. Single-band images, false color images, virtual 3D surface view images, and color-coded spectral clustering results were produced to highlight the skin structures for histological evaluation. Unlike traditional histological analysis with light microscopy, the molecular hyperspectral imaging technology can enhance the visualization of skin structures using their spectral signatures and their gray values. This technology has potential for the diagnosis and histopathologic characterization of different kind of skin cells. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  20. Optical single-sideband modulation based on silicon-on-insulator coupled-resonator optical waveguides

    NASA Astrophysics Data System (ADS)

    Song, Shijie; Yi, Xiaoke; Chew, Suen Xin; Li, Liwei; Nguyen, Linh; Zheng, Rongkun

    2016-03-01

    We propose and demonstrate for the first time an optical single-sideband (OSSB) modulation generation based on silicon-on-insulator coupled-resonator optical waveguides (CROWs) capable of operating at wide bandwidth with enhanced sideband suppression. The optimum order of the CROW filter was synthesized based on comprehensive performance analysis including optical sideband suppression and electrical power variation. Experimental results demonstrate an OSSB signal with sideband suppression as large as 23 dB. The performance of the proposed OSSB was demonstrated via compensating radio frequency (RF) power degradation in the transmission of the RF signal within the fiber.

  1. Multiscale toggle contrast operator-based mineral image enhancement.

    PubMed

    Bai, X; Zhou, F

    2011-08-01

    Mineral image is one type of crucial data for mineral research and analysis. However, some mineral images are not clear in some cases. To efficiently enhance mineral images and therefore benefit the applications of these images, a multiscale toggle contrast operator based algorithm is proposed in this paper. First, the toggle contrast operator is discussed. Secondly, the multiscale toggle contrast operator using structuring elements with different sizes is given. Thirdly, the multiscale toggle contrast operator is used to enhance the original image at different scales. Finally, the final enhanced image is constructed from the multiscale enhanced results. Because multiscale structuring elements are used, the algorithm performs efficiently and produces few noises. Experimental results show that the proposed algorithm is efficient for mineral image enhancement. More importantly, the proposed algorithm could be also used in other types of images, such as visual image, medical image and so on, for image enhancement. © 2011 The Authors Journal of Microscopy © 2011 Royal Microscopical Society.

  2. Enhanced magnetostriction derived from magnetic single domain structures in cluster-assembled SmCo films.

    PubMed

    Bai, Yulong; Yang, Bo; Guo, Fei; Lu, Qingshan; Zhao, Shifeng

    2017-09-13

    Cluster-assembled SmCo alloy films were prepared by low energy cluster beam deposition. The structure, magnetic domain, magnetization, and magnetostriction of the films were characterized. It is shown that the as-prepared films are assembled in compact and uniformly distributed spherical cluster nanoparticles, most of which, after vacuum in-situ annealing at 700 K, aggregated to form cluster islands. These cluster islands result in transformations from superparamagnetic states to magnetic single domain (MSD) states in the films. Such MSD structures contribute to the enhanced magnetostrictive behaviors with a saturation magnetostrictive coefficient of 160×10-6 in comparison to 105×10-6 for the as-prepared films. This work demonstrates candidate materials that could be applied in nano-electro-mechanical systems (NEMS), low power information storage, and weak magnetic detecting devices. © 2017 IOP Publishing Ltd.

  3. 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.

  4. Graphene enhances Li storage capacity of porous single-crystalline silicon nanowires.

    PubMed

    Wang, Xiao-Liang; Han, Wei-Qiang

    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/AgNO3 etching process. The Si porous nanowire/graphene electrode realized a charge capacity of 2470 mAh g(-1) that is much higher than the 1256 mAh g(-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. Surface-enhanced Raman spectroscopy at single-molecule scale and its implications in biology.

    PubMed

    Wang, Yuling; Irudayaraj, Joseph

    2013-02-05

    Single-molecule (SM) spectroscopy has been an exciting area of research offering significant promise and hope in the field of sensor development to detect targets at ultra-low levels down to SM resolution. To the experts and developers in the field of surface-enhanced Raman spectroscopy (SERS), this has often been a challenge and a significant opportunity for exploration. Needless to say, the opportunities and excitement of this multidisciplinary area impacts span the fields of physics, chemistry and engineering, along with a significant thrust in applications constituting areas in medicine, biology, environment and agriculture among others. In this review, we will attempt to provide a quick snapshot of the basics of SM-SERS, nanostructures and devices that can enable SM Raman measurement. We will conclude with a discussion on SERS implications in biomedical sciences.

  6. 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.

  7. Single-molecule electrical biosensors based on single-walled carbon nanotubes.

    PubMed

    Guo, Xuefeng

    2013-07-05

    Interactions between biological molecules are fundamental to biology. Probing the complex behaviors of biological systems at the molecular level provides new opportunities to uncover the wealth of molecular information that is usually hidden in conventional ensemble experiments and address the "unanswerable" questions in the physical, chemical and biological sciences. Nanometer-scale materials are particularly well matched with biomolecular interactions due to their biocompatibility, size comparability, and remarkable electrical properties, thus setting the basis for biological sensing with ultrahigh sensitivity. This brief review aims to highlight the recent progress of the burgeoning field of single-molecule electrical biosensors based on nanomaterials, with a particular focus on single-walled carbon nanotubes (SWNTs), for better understanding of the molecular structure, interacting dynamics, and molecular functions. The perspectives and key issues that will be critical to the success of next-generation single-molecule biosensors toward practical applications are also discussed, such as the device reproducibility, system integration, and theoretical simulation. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Single image super-resolution based on image patch classification

    NASA Astrophysics Data System (ADS)

    Xia, Ping; Yan, Hua; Li, Jing; Sun, Jiande

    2017-06-01

    This paper proposed a single image super-resolution algorithm based on image patch classification and sparse representation where gradient information is used to classify image patches into three different classes in order to reflect the difference between the different types of image patches. Compared with other classification algorithms, gradient information based algorithm is simpler and more effective. In this paper, each class is learned to get a corresponding sub-dictionary. High-resolution image patch can be reconstructed by the dictionary and sparse representation coefficients of corresponding class of image patches. The result of the experiments demonstrated that the proposed algorithm has a better effect compared with the other algorithms.

  9. 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.

  10. 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.

  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 molecule thermodynamics and nanopore-based thermometry

    NASA Astrophysics Data System (ADS)

    Reiner, Joseph E.; Robertson, Joseph W. F.; Burden, Lisa K.; Burden, Daniel L.; Kasianowicz, John J.

    2012-02-01

    The nanopore-based resistive pulse method measures the reduction in ionic current caused by the interaction of single molecules with the pore. It has great promise in addressing problems across a range of fields that include biomedicine and genomics. The technique requires the residence time of the molecules in the pore to exceed the inverse bandwidth of the detection system (˜ 10 μs). Efforts are underway to improve this by molecular modification of the pore wall, but little effort has focused on modifying the solution conditions in and around the pore. We address this issue by precisely controlling the solution temperature around a protein ion channel (alpha hemolysin) via laser-induced heating of gold nanoparticles. In this technique, the nanopore serves dual roles as both a highly local thermometer and single molecule sensor. Preliminary data suggests that the solution temperature can be controlled over a wide range, the nanopore conductance can be used to directly measure rapid changes in temperature, and the temperature change can dramatically alter the interaction kinetics of single molecules with the nanopore. The method will improve the development of biochip sensors and lead to a new platform for single molecule thermodynamic studies.

  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

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

    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.

  15. A single-layer peptide nanofiber for enhancing the cytotoxicity of trastuzumab (anti-HER)

    NASA Astrophysics Data System (ADS)

    Malik, Ruchi; Wagh, Anil; Qian, Steven; Law, Benedict

    2013-06-01

    A multivalent system is often employed to enhance the effectiveness of a targeted therapy. In the present study, we report a single-layer peptide nanofiber (NFP) as a multivalent targeting platform to improve the cytotoxicity of trastuzumab (anti-HER), a monoclonal antibody targeting the human epidermal growth factor receptor 2 (HER-2) in approximately 20 % of breast cancer patients. The trastuzumab-conjugated nanofiber (anti-HER/NFP) was 100 × 4 nm in size and was assembled from multiple peptide units (mPEG-BK( FITC)SGASNRA-kldlkldlkldl-CONH2). The optimized preparation was attached with approximately 10 antibodies at the surface. Because of an increase in the multivalency, anti-HER/NFP was able to truncate more cell surface HER-2 and, thus, showed an enhanced cytotoxicity toward HER-2 positive SKBr-3 human breast cancer as compared to the free anti-HER. Western blot analysis and fluorescence microscopic studies confirmed that there was a significant downregulation of the HER-2 level and also inhibition of the cell survival cell signaling pathways including the phosphatidylinositol 3-kinase (PI3K) and the mitogen activated protein kinase (MAPK) pathway. Our data suggested that NFP can be useful as a multivalent platform for immunotherapy, especially in combination with other chemotherapeutic agents in the future.

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

    PubMed

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

    2016-09-23

    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.

  17. ZnO nanoflowers with single crystal structure towards enhanced gas sensing and photocatalysis.

    PubMed

    Zhang, Sha; Chen, Hsueh-Shih; Matras-Postolek, Katarzyna; Yang, Ping

    2015-11-11

    In this paper, ZnO nanoflowers (NFs) were fabricated by thermal decomposition in an organic solvent and their application in gas sensors and photocatalysis was investigated. These single crystal ZnO NFs, which were observed for the first time, with an average size of ∼60 nm and were grown along the {100} facet. It was suggested that oleylamine used in the synthesis inhibited the growth and agglomeration of ZnO through the coordination of the oleylamine N atoms. The NFs exhibited excellent selectivity to acetone with a concentration of 25 ppm at 300 °C because they had a high specific surface area that provided more active sites and the surface adsorbed oxygen species for interaction with acetone. In addition, the ZnO NFs showed enhanced gas sensing response which was also ascribed to abundant oxygen vacancies at the junctions between petals of the NFs. Furthermore, ZnO-reduced graphene oxide (RGO) composites were fabricated by loading the ZnO NFs on the surface of the stratiform RGO sheet. In the photodegradation of rhodamine B tests, the composite revealed an enhanced photocatalytic performance compared with ZnO NFs under UV light irradiation.

  18. 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

  19. The structural basis for giant enhancement enabling single-molecule Raman scattering

    PubMed Central

    Wang, Zhenjia; Pan, Shanlin; Krauss, Todd D.; Du, Hui; Rothberg, Lewis J.

    2003-01-01

    We find that giant surface-enhanced Raman scattering for adsorbates on silver surfaces is present only on surfaces that exhibit self-similar fractal topology as inferred from atomic force microscopy. The fractal character results in localizing the energy of incident photons to volumes of a few nanometers on a side, millions of times smaller than the diffraction limit. Consistent with this finding, we have found an enhancement in spontaneous Raman cross section of >13 orders of magnitude for adsorbates on silver surfaces demonstrated to be fractal. The location of “hot spots” on the fractal surfaces is found to be hypersensitive to incident wavelength and polarization even though the observed Raman scattering is strictly linear in incident intensity. These observations are consistent with localization of the photon energy facilitated by the disordered nature of fractal organization through interference between the incident wave and scattered radiation from silver nanoparticle surface plasmons. We also present a surface preparation method that consistently produces fractal topologies that support single-molecule Raman scattering. PMID:12840144

  20. Enhancing Air Base Defense Through Joint Doctrine

    DTIC Science & Technology

    2009-01-01

    Security Forces, "Security Forces Transformation" brief to the Air Force CORONA Conference, Dec 2004. -- 2 Alan Vick, Snakes in the Eagles Nest (Santa Monica...Threat to U.S. Air Force Bases (Santa Monica, CA: Rand Publishing,1995),21. 4 Vick, Snakes in the Eagles Nest" 21. 5 Ibid, 112. 6 Ibid, 62. 7 Joseph N...Publishing, 50th Anniversary ed., 2000), 115. 10 Vick, Snakes in the Eagles Nest, 14. 11 Ibid, 71. 12 Ibid, 19. 13 Phillip B. Davidson, Vietnam at War

  1. 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.

  2. Single crystalline β-SiAlON nanowhiskers: preparation and enhanced properties at high temperature.

    PubMed

    Hou, Xinmei; Yu, Ziyou; Chen, Zhiyuan; Zhao, Baojun; Chou, Kuo-Chih

    2012-06-21

    Single crystalline β-SiAlON (z = 1.0) nanowhiskers with uniform morphology were prepared using a reaction sintering method at 1773 K for 6 h under flowing nitrogen atmosphere. The as-synthesized whiskers were well-crystallized with about 100-200 nm in diameter and a few hundred microns in length. According to the thermodynamic calculation, Al(g) and SiO(g) are important intermediate reactants to synthesize β-SiAlON whiskers. In the experiment, the two phases was controlled by changing the flow rate of nitrogen to make β-SiAlON whiskers grow in a stable way. The formation of β-SiAlON whiskers occurred through a vapor-solid (VS) mechanism. SiAlON was found to grow as a single crystal whisker from the (10 ̅10) plane of the granule. Furthermore, an enhanced oxidation resistance for β-SiAlON whiskers at high temperature was also observed using the thermogravimetry method (TG), demonstrating that β-SiAlON whiskers with uniform morphology is a promising candidate as a reinforcing agent in composite.

  3. A single mutation in Securin induces chromosomal instability and enhances cell invasion.

    PubMed

    Mora-Santos, Mar; Castilla, Carolina; Herrero-Ruiz, Joaquín; Giráldez, Servando; Limón-Mortés, M Cristina; Sáez, Carmen; Japón, Miguel Á; Tortolero, Maria; Romero, Francisco

    2013-01-01

    Pituitary tumour transforming gene (pttg1) encodes Securin, a protein involved in the inhibition of sister chromatid separation binding to Separase until the onset of anaphase. Separase is a cysteine-protease that degrades cohesin to segregate the sister chromatids to opposite poles of the cell. The amount of Securin is strongly regulated because it should allow Separase activation when it is degraded by the anaphase promoting complex/cyclosome, should arrest the cell cycle after DNA damage, when it is degraded through SKP1-CUL1-βTrCP ubiquitin ligase, and its overexpression induces tumour formation and correlates with metastasis in multiple tumours. Securin is a phosphoprotein that contains 32 potentially phosphorylatable residues. We mutated and analysed most of them, and found a single mutant, hSecT60A, that showed enhanced oncogenic properties. Our fluorescence activated cell sorting analysis, fluorescence in situ hybridisation assays, tumour cell migration and invasion experiments and gene expression by microarrays analysis clearly involved hSecT60A in chromosomal instability and cell invasion. These results show, for the first time, that a single mutation in pttg1 is sufficient to trigger the oncogenic properties of Securin. The finding of this point mutation in patients might be used as an effective strategy for early detection of cancer. Copyright © 2012 Elsevier Ltd. All rights reserved.

  4. Self-enhancement processing in the default network: a single-pulse TMS study.

    PubMed

    Luber, Bruce; Lou, Hans C; Keenan, Julian P; Lisanby, Sarah H

    2012-11-01

    Much research has been done on positive self-evaluation and its relationship to mental health. However, little is known about its neural underpinnings. Imaging studies have suggested that the brain's default network is involved with self-related processing and that one portion of the default network, medial prefrontal cortex (MPFC), is particularly involved with self-evaluation. Here, we used transcranial magnetic stimulation (TMS) to causally demonstrate that this network, and particularly MPFC, is involved with self-evaluative processing. In a first experiment, 27 healthy volunteers judged whether adjectives, evenly divided between desirable and undesirable traits, described themselves or their best friends, and a robust self-enhancement bias effect was found. In a second experiment, single-pulse TMS was applied targeting three locations (MPFC and left and right parietal cortex) in a different group of healthy volunteers while they performed the adjective task. In each trial, TMS was applied at one of five different times relative to onset of the adjective ranging from 0 to 480 ms. TMS affected self-enhancement bias in a site- and latency-specific manner: at MPFC, the self-enhancement bias actually reversed at 160 ms, with subjects favoring their best friend over themselves. TMS may thus be of use in investigating areas of mental illness in which self-evaluation is abnormal, potentially as a diagnostic tool. In addition, the present study, combined with our previous reports (Lou et al., Proc Natl Acad Sci USA 101(17):6827-6832, 2004, Exp Brain Res 207:27-38, 2010), causally demonstrates two kinds of self-related processing within the default network, one centered in parietal cortex and concerned with retrieval of self-related associations, and the other MPFC-centered and involved in self-evaluative processing.

  5. Sensitivity-enhanced temperature sensor with cascaded fiber optic Sagnac interferometers based on Vernier-effect

    NASA Astrophysics Data System (ADS)

    Shao, Li-Yang; Luo, Yuan; Zhang, Zhiyong; Zou, Xihua; Luo, Bin; Pan, Wei; Yan, Lianshan

    2015-02-01

    A novel fiber optic temperature sensor has been proposed and experimentally demonstrated with ~9 times sensitivity enhancement by using two cascaded Sagnac interferometers. These two Sagnac interferometers consist of the same type of polarization maintaining fibers with slightly different lengths. The working principle is analogous to a Vernier scale. One interferometer acts as filter, while the other is for temperature sensing. The envelope of the cascaded sensor shifts much more than single one with a certain enhancement factor, which related to the free space range difference between the filter and sensor interferometers. Experimental results show that the temperature sensitivity is enhanced from -1.46 nm/°C based on single Sagnac configuration to -13.36 nm/°C.

  6. Segregation in water-based stable single-bubble sonoluminescence.

    PubMed

    Levinsen, Mogens T

    2012-01-01

    A long-standing issue in the field of long-time-stable, water-based, single-bubble sonoluminescence has been the close similarity of the spectra to that of blackbody radiation, the question being whether the similarity is just a weird coincidence, with the bubbles being, on the whole, transparent to their own radiation. One mechanism that has been suggested is the generation of a shock or, at least, a compression wave in the gas of the bubble. A footprint of such a wave would be segregation of species. We have investigated spectra from bubbles seeded with various mixtures of helium or neon with xenon or argon using a transformation, specific to our experimental setup and spectrometer, that was shown to allow for a single-parameter characterization of the spectra in some simpler situations. The surprising result of this investigation is that although no trace of segregation is found, the radiation seems to be highly thermalized in all cases.

  7. Understanding the kinetic mechanism of RNA single base pair formation

    PubMed Central

    Xu, Xiaojun; Yu, Tao; Chen, Shi-Jie

    2016-01-01

    RNA functions are intrinsically tied to folding kinetics. The most elementary step in RNA folding is the closing and opening of a base pair. Understanding this elementary rate process is the basis for RNA folding kinetics studies. Previous studies mostly focused on the unfolding of base pairs. Here, based on a hybrid approach, we investigate the folding process at level of single base pairing/stacking. The study, which integrates molecular dynamics simulation, kinetic Monte Carlo simulation, and master equation methods, uncovers two alternative dominant pathways: Starting from the unfolded state, the nucleotide backbone first folds to the native conformation, followed by subsequent adjustment of the base conformation. During the base conformational rearrangement, the backbone either retains the native conformation or switches to nonnative conformations in order to lower the kinetic barrier for base rearrangement. The method enables quantification of kinetic partitioning among the different pathways. Moreover, the simulation reveals several intriguing ion binding/dissociation signatures for the conformational changes. Our approach may be useful for developing a base pair opening/closing rate model. PMID:26699466

  8. 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

  9. Too Hot for Photon-Assisted Transport: Hot-Electrons Dominate Conductance Enhancement in Illuminated Single-Molecule Junctions.

    PubMed

    Fung, E-Dean; Adak, Olgun; Lovat, Giacomo; Scarabelli, Diego; Venkataraman, Latha

    2017-02-08

    We investigate light-induced conductance enhancement in single-molecule junctions via photon-assisted transport and hot-electron transport. Using 4,4'-bipyridine bound to Au electrodes as a prototypical single-molecule junction, we report a 20-40% enhancement in conductance under illumination with 980 nm wavelength radiation. We probe the effects of subtle changes in the transmission function on light-enhanced current and show that discrete variations in the binding geometry result in a 10% change in enhancement. Importantly, we prove theoretically that the steady-state behavior of photon-assisted transport and hot-electron transport is identical but that hot-electron transport is the dominant mechanism for optically induced conductance enhancement in single-molecule junctions when the wavelength used is absorbed by the electrodes and the hot-electron relaxation time is long. We confirm this experimentally by performing polarization-dependent conductance measurements of illuminated 4,4'-bipyridine junctions. Finally, we perform lock-in type measurements of optical current and conclude that currents due to laser-induced thermal expansion mask optical currents. This work provides a robust experimental framework for studying mechanisms of light-enhanced transport in single-molecule junctions and offers tools for tuning the performance of organic optoelectronic devices by analyzing detailed transport properties of the molecules involved.

  10. 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.

  11. 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.

  12. Rectifying enhancement induced by conjugation breaking in thiolated arylethynylene single-molecular diodes

    NASA Astrophysics Data System (ADS)

    Zuo, Xi; Chu, Lei; Zhang, Guang-Ping; Wang, Chuan-Kui

    2016-10-01

    Rectifying properties of three cyano side group substituted arylethynylene thiolate molecules are theoretically investigated based on abinitio calculations. The current-voltage curves show that rectifying performance of the junctions correlates negatively with conjugation of the molecules, which reveals a much more pronounced rectification behavior for that with broken-conjugated dihydroanthracene core (sAH) than the counterpart with linearly-conjugated anthracene core (sAC) or cross-conjugated anthraquinone core (sAQ). It is demonstrated that the conjugation breaking induced localization of molecular orbital and asymmetric evolution of its spatial distribution under positive and negative biases play the key role for the rectification enhancement in sAH.

  13. Efficiency enhancement for the orbital angular momentum photon quantum interface via single photon frequency upconversion

    NASA Astrophysics Data System (ADS)

    Wu, Wen-jie; Ma, Jian-hui; Pan, Hai-feng; Wu, E.; Chen, Huai-xi; Dismas, K. Choge; Liang, Wan-guo

    2017-03-01

    As the application of orbital angular momentum ( OAM) of photon quantum in quantum communication, the OAM photon quantum interface for the transmission wavelength from the telecom communication quantum information storage in visible regime is required. Here we demonstrate the efficiency enhancement for the OAM photon quantum interface based on the frequency upconversion from telecom wavelength to visible regime by sum-frequency generation. The infrared photons at 1 558 nm carrying different OAM values could be converted to the visible regime at 622.2 nm with the optimal efficiency via adjusting the pump beam waist radius and intensity.

  14. Hyperspectral surface-enhanced Raman imaging of labeled silver nanoparticles in single cells

    NASA Astrophysics Data System (ADS)

    Wabuyele, Musundi B.; Yan, Fei; Griffin, Guy D.; Vo-Dinh, Tuan

    2005-06-01

    We describe the development of an acousto-optic tunable filter (AOTF)-based hyperspectral surface-enhanced Raman imaging (HSERI) system equipped with an intensified charged coupled device and an avalanche photodiode. The AOTF device is a miniature rapid-scanning solid-state device that has no moving parts and can be rapidly tuned (microseconds) either sequentially or randomly, over a wide spectral range between 600 and 900nm [corresponding to a large relative wave number range (˜0-4500cm-1)], with respect to a 632.8nm excitation and can also acquire images at a fairly narrow band of ˜7cm-1. In this article we describe a confocal surface-enhanced Raman imaging (SERI) system developed in our laboratory that combines hyperspectral imaging capabilities with surface-enhanced Raman scattering (SERS) to identify cellular components with high spatial and temporal resolution. The HSERI system's application to cellular imaging is demonstrated using SERS-labeled nanoparticles in cellular systems.

  15. Enhancing ionic conductivity of bulk single-crystal yttria-stabilized zirconia by tailoring dopant distribution

    SciTech Connect

    Lee, E.; Prinz, F. B.; Cai, W.

    2011-02-11

    We present an ab initio–based kinetic Monte Carlo model for ionic conductivity in single-crystal yttria-stabilized zirconia. Ionic interactions are taken into account by combining density functional theory calculations and the cluster expansion method and are found to be essential in reproducing the effective activation energy observed in experiments. The model predicts that the effective energy barrier can be reduced by 0.15–0.25 eV by arranging the dopant ions into a superlattice.

  16. 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.

  17. The Relationship of Learning to Technology-Based Enhancements.

    ERIC Educational Resources Information Center

    Christensen, Dean L.; Tennyson, Robert D.

    1988-01-01

    Discussion of educational technology and its impact on instructional methodology and the learning process focuses on six basic educational components necessary to trace technology variables directly to specific learning processes. Highlights include learning objectives; knowledge bases; instructional strategies; computer-based enhancements; and…

  18. 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.

  19. Single-ion dosemeter based on floating gate memories.

    PubMed

    Cellere, G; Paccagnella, A; Visconti, A; Bonanomi, M; McNulty, P J

    2006-01-01

    Floating Gate (FG) nonvolatile memories are based on a tiny polysilicon layer (the FG) which can be permanently charged with electrons or holes, thus changing the threshold voltage of a MOSFET. Every time a FG is hit by a high energy ion, it experiences a charge loss, depending on the ion linear energy transfer (LET) and on the transistor geometrical and electrical characteristics. This paper discusses the opportunities to use this devices as single an ion dosemeter with sub-micrometer spatial resolution and capable of distinguish the impinging ion LET.

  20. Physically Based Kinematic Hardening Modelling of Single Crystal

    NASA Astrophysics Data System (ADS)

    Balland, P.; Déprés, C.; Billard, R.; Tabourot, L.

    2011-05-01

    This paper suggests a new method to take into account the kinematic hardening in constitutive behaviour of metallic face centred cubic single crystal. The keystone of this model is that kinematic effect arises from a description of the crystal dislocation microstructure based on a heterogeneous distribution of slip strength. In this paper, these concepts are applied to crystalline plasticity models. In particular, simulations of monotonous tensile test and cyclic loading are analysed to show that implementation of the proposed concepts, without any additional complexity, gives the current model a wide range of applications from small cycled strains to large monotonous ones.

  1. ZnO single nanowire-based UV detectors

    NASA Astrophysics Data System (ADS)

    Das, Sachindra Nath; Moon, Kyeong-Ju; Kar, Jyoti Prakash; Choi, Ji-Hyuk; Xiong, Junjie; Lee, Tae Il; Myoung, Jae-Min

    2010-07-01

    In this report, ZnO single nanowire (NW)-based devices were fabricated on the same nanowire by e-beam lithography so that both sides had Ohmic contact and one side had Schottky contact. Information about the mechanism for low-power UV detection by these devices was unambiguously provided by I-V measurements. Adsorption and desorption of oxygen molecules at the NW surface are responsible for the UV detection by the device with Ohmic contacts on both sides. Barrier height modulations and interface states are responsible for UV detection by the device with Schottky contact on one side.

  2. Phototransistor based on single In₂Se₃ nanosheets.

    PubMed

    Li, Qin-Liang; Liu, Chang-Hai; Nie, Yu-Ting; Chen, Wen-Hua; Gao, Xu; Sun, Xu-Hui; Wang, Sui-Dong

    2014-11-06

    Micrometer-sized single-crystalline In₂Se₃ nanosheets are synthesized by epitaxial growth from In₂Se₃nanowires. The In₂Se₃ nanosheets possess anisotropic structural configuration with intralayer covalent bonding and interlayer van der Waals bonding. Phototransistors based on the In₂Se₃ nanosheets are realized, and the devices show high photoresponsivity and high photo On/Off ratio up to two orders. The photo-gating effect can be modulated by the gate bias, indicating potential utility of the In₂Se₃ nanosheets in a variety of optoelectronic applications.

  3. Performance enhancement of a silicon MEMS piezoresistive single axis accelerometer with electroplated gold on a proof mass

    NASA Astrophysics Data System (ADS)

    Sankar, A. Ravi; Lahiri, S. K.; Das, S.

    2009-02-01

    Performance enhancement of a silicon MEMS piezoresistive single axis accelerometer with electroplated gold on a proof mass is presented in this paper. The fabricated accelerometer device consists of a heavy proof mass supported by four thin flexures. Boron-diffused piezoresistors located near the fixed ends of the flexures are used for sensing the developed stress and hence acceleration. Performance enhancement is achieved by electroplating a gold mass of 20 µm thickness on top of the proof mass. A commercially available sulfite-based solution TSG-250™ was used for the electroplating process. Aluminum metal lines were used to form a Wheatstone bridge for signal pick-up. To avoid galvanic corrosion between two dissimilar metals having contact in an electrolyte, a shadow mask technique was used to selectively deposit a Cr/Au seed layer on an insulator atop the proof mass for subsequent electrodeposition. Bulk micromachining was performed using a 5% dual-doped TMAH solution. Fabricated devices with different electroplated gold areas were tested up to ±13 g acceleration. For electroplated gold dimensions of 2500 µm × 2500 µm × 20 µm on a proof mass, sensitivity along the Z-axis is increased by 21.8% as compared to the structure without gold. Off-axis sensitivities along the X- and Y-axes are reduced by 7.6% and 6.9%, respectively.

  4. 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

  5. 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.

  6. Single-Pass Clustering Algorithm Based on Storm

    NASA Astrophysics Data System (ADS)

    Fang, LI; Longlong, DAI; Zhiying, JIANG; Shunzi, LI

    2017-02-01

    The dramatically increasing volume of data makes the computational complexity of traditional clustering algorithm rise rapidly accordingly, which leads to the longer time. So as to improve the efficiency of the stream data clustering, a distributed real-time clustering algorithm (S-Single-Pass) based on the classic Single-Pass [1] algorithm and Storm [2] computation framework was designed in this paper. By employing this kind of method in the Topic Detection and Tracking (TDT) [3], the real-time performance of topic detection arises effectively. The proposed method splits the clustering process into two parts: one part is to form clusters for the multi-thread parallel clustering, the other part is to merge the generated clusters in the previous process and update the global clusters. Through the experimental results, the conclusion can be drawn that the proposed method have the nearly same clustering accuracy as the traditional Single-Pass algorithm and the clustering accuracy remains steady, computing rate increases linearly when increasing the number of cluster machines and nodes (processing threads).

  7. 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.

  8. Enhancing Interprofessional Education With Team-based Learning.

    PubMed

    Buhse, Marijean; Della Ratta, Carol

    2017-03-01

    Interprofessional education (IPE) has gained momentum across health profession schools in simulation and clinical settings. Exploring interprofessional experiences in the classroom setting may further enhance collaborative skills while advancing clinical knowledge. The authors describe an innovative approach to IPE to teach chronic care concepts to graduate nursing, physician assistant, and public health students. Enhancing IPE with a team-based learning approach resulted in improved knowledge of chronic care management, student perceptions of mutual respect, and perceived development of communication and teamwork skills.

  9. 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.

  10. 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

  11. 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.

  12. 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.

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

    PubMed

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

    2016-06-27

    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.

  14. Panoramic stereo photography based on single-lens with a double-symmetric prism.

    PubMed

    Chen, Chien-Yue; Deng, Qing-Long; Sun, Wen-Shing; Cheng, Qiao-Yao; Lin, Bor-Shyh; Su, Ching-Lung

    2013-04-08

    Different from traditional panorama stereo acquisition technique shooting with numerous cameras, this study equips a double-symmetric prism in front of a single-lens camera to acquire images from four different angles of view, and the images acquired from the cameras every 20 degrees complete a pair of panorama stereo images with vertical angle of view ( ± 16 degrees) by image-based rendering. The panorama stereo acquisition technique reduces the number of cameras by three-fourth, and the acquired images contain vertical angles of view. Moreover, the image resolution is enhanced several times of the resolution of integral photography without moiré effect.

  15. Enhancement of fiber orientation distribution reconstruction in diffusion-weighted imaging by single channel blind source separation.

    PubMed

    Jing, Min; McGinnity, T Martin; Coleman, Sonya; Zhang, Huaizhong; Fuchs, Armin; Kelso, J A Scott

    2012-02-01

    In diffusion-weighted imaging (DWI), reliable fiber tracking results rely on the accurate reconstruction of the fiber orientation distribution function (fODF) in each individual voxel. For high angular resolution diffusion imaging (HARDI), deconvolution-based approaches can reconstruct the complex fODF and have advantages in terms of computational efficiency and no need to estimate the number of distinct fiber populations. However, HARDI-based methods usually require relatively high b-values and a large number of gradient directions to produce good results. Such requirements are not always easy to meet in common clinical studies due to limitations in MRI facilities. Moreover, most of these approaches are sensitive to noise. In this study, we propose a new framework to enhance the performance of the spherical deconvolution (SD) approach in low angular resolution DWI by employing a single channel blind source separation (BSS) technique to decompose the fODF initially estimated by SD such that the desired fODF can be extracted from the noisy background. The results based on numerical simulations and two phantom datasets demonstrate that the proposed method achieves better performance than SD in terms of robustness to noise and variation in b-values. In addition, the results show that the proposed method has the potential to be applied to low angular resolution DWI which is commonly used in clinical studies. © 2011 IEEE

  16. Surface recrystallization of a single crystal nickel-base superalloy

    NASA Astrophysics Data System (ADS)

    Meng, Jie; Jin, Tao; Sun, Xiao-Feng; Hu, Zhuang-Qi

    2011-04-01

    The recrystallization behavior of a single crystal nickel-base superalloy was investigated by shot peening and subsequent annealing. Two kinds of recrystallization microstructures, which are intensively dependent on the annealing temperature, are shown in the nickel-base superalloy after shot peening and subsequent annealing. Surface recrystallized grains are obtained when the superalloy is annealed at solution treatment temperature. The nucleation of recrystallization originates from the dendritic core, where rapid dissolution of γ' particles occurs. Cellular recrystallization is observed after annealing at lower temperatures. Cellular structures induced by high diffusivity of the moving boundary and more γ' particles dissolution led by residual stress are developed from the surface region. Recrystallized kinetics of the shot-peened alloy annealed at 1050°C accords with the Johnson-Mehl-Avrami-Kolmogorov equation. The low Avrami exponent is caused by the inhomogeneous distribution of stored energy, the decreasing of stored energy during recovery, and the strong resistance of boundary migration by γ' particles.

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

    PubMed Central

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

    2014-01-01

    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 discuss the requirements of each design, followed by advantages and disadvantages. The logic and methods for evaluating effects in SSED are reviewed as well as contemporary issues regarding data analysis with SSED data sets. Examples of challenges in executing SSEDs are included. Specific exemplars of how SSEDs have been used in speech-language pathology research are provided throughout. Conclusion SSED studies provide a flexible alternative to traditional group designs in the development and identification of evidence-based practice in the field of communication sciences and disorders. PMID:23071200

  18. Review of Electronics Based on Single-Walled Carbon Nanotubes.

    PubMed

    Cao, Yu; Cong, Sen; Cao, Xuan; Wu, Fanqi; Liu, Qingzhou; Amer, Moh R; Zhou, Chongwu

    2017-08-14

    Single-walled carbon nanotubes (SWNTs) are extremely promising materials for building next-generation electronics due to their unique physical and electronic properties. In this article, we will review the research efforts and achievements of SWNTs in three electronic fields, namely analog radio-frequency electronics, digital electronics, and macroelectronics. In each SWNT-based electronic field, we will present the major challenges, the evolutions of the methods to overcome these challenges, and the state-of-the-art of the achievements. At last, we will discuss future directions which could lead to the broad applications of SWNTs. We hope this review could inspire more research on SWNT-based electronics, and accelerate the applications of SWNTs.

  19. 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

  20. 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.

  1. 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.

  2. Enhanced thermoelectric performance of graphene nanoribbon-based devices

    SciTech Connect

    Hossain, Md Sharafat Huynh, Duc Hau; Nguyen, Phuong Duc; Jiang, Liming; Nguyen, Thanh Cong; Al-Dirini, Feras; Hossain, Faruque M.; Skafidas, Efstratios

    2016-03-28

    There have been numerous theoretical studies on exciting thermoelectric properties of graphene nano-ribbons (GNRs); however, most of these studies are mainly based on simulations. In this work, we measure and characterize the thermoelectric properties of GNRs and compare the results with theoretical predictions. Our experimental results verify that nano-structuring and patterning graphene into nano-ribbons significantly enhance its thermoelectric power, confirming previous predictions. Although patterning results in lower conductance (G), the overall power factor (S{sup 2}G) increases for nanoribbons. We demonstrate that edge roughness plays an important role in achieving such an enhanced performance and support it through first principles simulations. We show that uncontrolled edge roughness, which is considered detrimental in GNR-based electronic devices, leads to enhanced thermoelectric performance of GNR-based thermoelectric devices. The result validates previously reported theoretical studies of GNRs and demonstrates the potential of GNRs for the realization of highly efficient thermoelectric devices.

  3. 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.

  4. 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.

  5. Design of NbN Superconducting Nanowire Single-Photon Detectors with Enhanced Infrared Detection Efficiency

    NASA Astrophysics Data System (ADS)

    Wang, Q.; Renema, J. J.; Engel, A.; de Dood, M. J. A.

    2017-09-01

    We optimize the design of NbN nanowire superconducting single-photon detectors using the recently discovered position-dependent detection efficiency in these devices. This optimized design of meandering wire NbN detectors maximizes absorption at positions where photon detection is most efficient by altering the field distribution across the wire. In order to calculate the response of the detectors with different geometries, we use a monotonic local detection efficiency from a nanowire and optical absorption distribution via finite-difference-time-domain simulations. The calculations predict a trade-off between average absorption and absorption at the edge, leading to a predicted optimal wire width close to 100 nm for a 1550-nm wavelength, which drops to a 50-nm wire width for a 600-nm wavelength. The absorption at the edges can be enhanced by depositing a silicon nanowire on top of the superconducting nanowire, which improves both the total absorption efficiency and the internal detection efficiency of meandering wire structures. The proposed structure can be integrated in a relatively simple cavity structure to reach absorption efficiencies of 97% for perpendicular and 85% for parallel polarization.

  6. 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

  7. Optical Field Confinement Enhanced Single ZnO Microrod UV Photodetector

    NASA Astrophysics Data System (ADS)

    Wei, Ming; Xu, Chun-Xiang; Qin, Fei-Fei; Gowri Manohari, Arumugam; Lu, Jun-Feng; Zhu, Qiu-Xiang

    2017-07-01

    ZnO microrods are synthesized using the vapor phase transport method, and the magnetron sputtering is used to decorate the Al nanoparticles (NPs) on a single ZnO microrod. The micro-PL and I-V responses are measured before and after the decoration of Al NPs. The FDTD stimulation is also carried out to demonstrate the optical field distribution around the decoration of Al NPs on the surface of a ZnO microrod. Due to an implementation of Al NPs, the ZnO microrod exhibits an improved photoresponse behavior. In addition, Al NPs induced localized surface plasmons (LSPs) as well as improved optical field confinement can be ascribed to an enhancement of ultraviolet (UV) response. This research provides a method for improving the responsivity of photodetectors. Supported by the National Natural Science Foundation of China under Grant Nos 61475035 and 61275054, the Science and Technology Support Program of Jiangsu Province under Grant No BE2016177, and the Collaborative Innovation Center of Suzhou Nano Science and Technology.

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

    PubMed Central

    Crane, Cory A.; Eckhardt, Christopher I.

    2014-01-01

    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 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. PMID:23506510

  9. 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.

  10. Enhanced indistinguishability of in-plane single photons by resonance fluorescence on an integrated quantum dot

    NASA Astrophysics Data System (ADS)

    Kalliakos, Sokratis; Brody, Yarden; Bennett, Anthony J.; Ellis, David J. P.; Skiba-Szymanska, Joanna; Farrer, Ian; Griffiths, Jonathan P.; Ritchie, David A.; Shields, Andrew J.

    2016-10-01

    Integrated quantum light sources in photonic circuits are envisaged as the building blocks of future on-chip architectures for quantum logic operations. While semiconductor quantum dots have been proven to be the highly efficient emitters of quantum light, their interaction with the host material induces spectral decoherence, which decreases the indistinguishability of the emitted photons and limits their functionality. Here, we show that the indistinguishability of in-plane photons can be greatly enhanced by performing resonance fluorescence on a quantum dot coupled to a photonic crystal waveguide. We find that the resonant optical excitation of an exciton state induces an increase in the emitted single-photon coherence by a factor of 15. Two-photon interference experiments reveal a visibility of 0.80 ± 0.03, which is in good agreement with our theoretical model. Combined with the high in-plane light-injection efficiency of photonic crystal waveguides, our results pave the way for the use of this system for the on-chip generation and transmission of highly indistinguishable photons.

  11. Hydrogen enhanced cracking studies on Fe-3wt%Si single and bi-crystal microcantilevers

    NASA Astrophysics Data System (ADS)

    Hajilou, T.; Deng, Y.; Kheradmand, N.; Barnoush, A.

    2017-06-01

    Hydrogen (H) enhanced cracking was studied in Fe-3wt%Si by means of in situ electrochemical microcantilever bending test. It was clearly shown that the presence of H causes hydrogen embrittlement (HE) by triggering crack initiation and propagation at the notch where stress concentration is existing. Additionally, the effect of carbon content and the presence of a grain boundary (GB) in the cantilever were studied. It was shown that in the presence of H the effect of carbon atom on pinning the dislocations is reduced. On the other hand, the presence of a GB, while the chemical composition of material kept constant, will promote the HE. Crack initiation and propagation occur in the presence of H, while the notch blunting was observed for both single and bi-crystalline beams bent in air. Post-mortem analysis of the crack propagation path showed that a transition from transgranular fracture to intragranular fracture mechanism is highly dependent on the position of the stress concentration relative to the GB. This article is part of the themed issue 'The challenges of hydrogen and metals'.

  12. Enhanced expression and purification of camelid single domain VHH antibodies from classical inclusion bodies.

    PubMed

    Maggi, Maristella; Scotti, Claudia

    2017-08-01

    Single domain antibodies (sdAbs) are small antigen-binding domains derived from naturally occurring, heavy chain-only immunoglobulins isolated from camelid and sharks. They maintain the same binding capability of full-length IgGs but with improved thermal stability and permeability, which justifies their scientific, medical and industrial interest. Several described recombinant forms of sdAbs have been produced in different hosts and with different strategies. Here we present an optimized method for a time-saving, high yield production and extraction of a poly-histidine-tagged sdAb from Escherichia coli classical inclusion bodies. Protein expression and extraction were attempted using 4 different methods (e.g. autoinducing or IPTG-induced soluble expression, non-classical and classical inclusion bodies). The best method resulted to be expression in classical inclusion bodies and urea-mediated protein extraction which yielded 60-70 mg/l bacterial culture. The method we here describe can be of general interest for an enhanced and efficient heterologous expression of sdAbs for research and industrial purposes. Copyright © 2017 Elsevier Inc. All rights reserved.

  13. 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.

  14. Community-based applications to enhance road safety.

    PubMed

    Spiegel, Rainer

    2010-01-01

    Road safety plays an increasing role in communities throughout the entire world. According to estimates, road accidents will have moved from ninth to third in the worldwide ranking of burden of disease by 2020. This theme issue is dedicated to community-based applications that have the aim to enhance road safety. Although various interventions will be demonstrated, this issue provides by no means an exhaustive overview of community-based applications. The applications presented in this issue are predominantly meant to stimulate ideas and discussion on what can be done to enhance road safety.

  15. 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

  16. DNA methylation analysis of chromosome 21 gene promoters at single base pair and single allele resolution.

    PubMed

    Zhang, Yingying; Rohde, Christian; Tierling, Sascha; Jurkowski, Tomasz P; Bock, Christoph; Santacruz, Diana; Ragozin, Sergey; Reinhardt, Richard; Groth, Marco; Walter, Jörn; Jeltsch, Albert

    2009-03-01

    Differential DNA methylation is an essential epigenetic signal for gene regulation, development, and disease processes. We mapped DNA methylation patterns of 190 gene promoter regions on chromosome 21 using bisulfite conversion and subclone sequencing in five human cell types. A total of 28,626 subclones were sequenced at high accuracy using (long-read) Sanger sequencing resulting in the measurement of the DNA methylation state of 580427 CpG sites. Our results show that average DNA methylation levels are distributed bimodally with enrichment of highly methylated and unmethylated sequences, both for amplicons and individual subclones, which represent single alleles from individual cells. Within CpG-rich sequences, DNA methylation was found to be anti-correlated with CpG dinucleotide density and GC content, and methylated CpGs are more likely to be flanked by AT-rich sequences. We observed over-representation of CpG sites in distances of 9, 18, and 27 bps in highly methylated amplicons. However, DNA sequence alone is not sufficient to predict an amplicon's DNA methylation status, since 43% of all amplicons are differentially methylated between the cell types studied here. DNA methylation in promoter regions is strongly correlated with the absence of gene expression and low levels of activating epigenetic marks like H3K4 methylation and H3K9 and K14 acetylation. Utilizing the single base pair and single allele resolution of our data, we found that i) amplicons from different parts of a CpG island frequently differ in their DNA methylation level, ii) methylation levels of individual cells in one tissue are very similar, and iii) methylation patterns follow a relaxed site-specific distribution. Furthermore, iv) we identified three cases of allele-specific DNA methylation on chromosome 21. Our data shed new light on the nature of methylation patterns in human cells, the sequence dependence of DNA methylation, and its function as epigenetic signal in gene regulation

  17. Surface-Enhanced Raman Scattering: Comparison of Three Different Molecules on Single-Crystal Nanocubes and Nanospheres of Silver

    PubMed Central

    Rycenga, Matthew; Kim, Moon Ho; Camargo, Pedro H. C.; Cobley, Claire; Li, Zhi-Yuan; Xia, Younan

    2009-01-01

    We have investigated the surface-enhanced Raman scattering (SERS) of chemically prepared single-crystal nanocubes and nanospheres of Ag with three different molecules to quantitatively understand the effect of sharp features on the SERS enhancement factor. Both experimental measurements and theoretical calculations confirmed a higher SERS activity for the nanocubes as a result of sharp features on their surfaces. We also found major discrepancies between the measured SERS intensities and those predicted from the electromagnetic mechanism. Through analysis of SERS bands, we concluded that sharp features on the Ag nanocubes could greatly increase the contribution of the chemical enhancement to the SERS intensity. PMID:19175302

  18. 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.

  19. Advanced piezoelectric single crystal based transducers for naval sonar applications

    NASA Astrophysics Data System (ADS)

    Snook, Kevin A.; Rehrig, Paul W.; Hackenberger, Wesley S.; Jiang, Xiaoning; Meyer, Richard J., Jr.; Markley, Douglas

    2005-05-01

    TRS is developing new transducers based on single crystal piezoelectric materials such as Pb(Mg1/3Nb2/3)x-1TixO3 (PMN-PT). Single crystal piezoelectrics such as PMN-PT exhibit very high piezoelectric coefficients (d33 ~ 1800 to >2000 pC/N) and electromechanical coupling factors (k33 > 0.9), respectively, which may be exploited for improving the performance of broad bandwidth and high frequency sonar. Apart from basic performance, much research has been done on reducing the size and increasing the output power of tonpilz transducers for sonar applications. Results are presented from two different studies. "33" mode single crystal tonpilz transducers have reduced stack lengths due to their low elastic stiffness relative to PZTs, however, this produces non-ideal aspect ratios due to large lateral dimensions. Alternative "31" resonance mode tonpilz elements are proposed to improve performance over these "33" designs. d32 values as high as 1600 pC/N have been observed, and since prestress is applied perpendicular to the poling direction, "31" mode Tonpilz elements exhibit lower loss and higher reliability than "33" mode designs. Planar high power tonpilz arrays are the optimum way to obtain the required acoustic pressure and bandwidth for small footprint, high power sensors. An important issue for these sensors is temperature and prestress stability, since fluctuations in tonpilz properties affects power delivery and sensing electronic design. TRS used the approach of modifying the composition of PMN-PT to improve the temperature dependence of properties of the material. Results show up to a 50% decrease in temperature change while losing minimal source level.

  20. 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.

  1. Bithermal fatigue of a nickel-base superalloy single crystal

    NASA Technical Reports Server (NTRS)

    Verrilli, Michael J.

    1988-01-01

    The thermomechanical fatigue behavior of a nickel-base superalloy single crystal was investigated using a bithermal test technique. The bithermal fatigue test was used as a simple alternative to the more complex thermomechanical fatigue test. Both in-phase and out-of-phase bithermal tests were performed on (100)-oriented coated and bare Rene N4 single crystals. In out-of-plane bithermal tests, the tensile and compressive halves of the cycle were applied isothermally at 760 and 982 C, respectively, while for the in-phase bithermal tests the temperature-loading sequence was reversed. The bithermal fatigue lives of bare specimens were shorter than the isothermal fatigue lives at either temperature extreme when compared on an inelastic strain basis. Both in-phase and out-of-phase bithermal fatigue life curves converged in the large strain regime and diverged in the small strain regime, out-of-phase resulting in the shortest lives. The coating had no effect on life for specimens cycled in-phase; however, the coating was detrimental for isothermal fatigue at 760 C and for out-of-phase fatigue under large strains.

  2. Ice flood velocity calculating approach based on single view metrology

    NASA Astrophysics Data System (ADS)

    Wu, X.; Xu, L.

    2017-02-01

    Yellow River is the river in which the ice flood occurs most frequently in China, hence, the Ice flood forecasting has great significance for the river flood prevention work. In various ice flood forecast models, the flow velocity is one of the most important parameters. In spite of the great significance of the flow velocity, its acquisition heavily relies on manual observation or deriving from empirical formula. In recent years, with the high development of video surveillance technology and wireless transmission network, the Yellow River Conservancy Commission set up the ice situation monitoring system, in which live videos can be transmitted to the monitoring center through 3G mobile networks. In this paper, an approach to get the ice velocity based on single view metrology and motion tracking technique using monitoring videos as input data is proposed. First of all, River way can be approximated as a plane. On this condition, we analyze the geometry relevance between the object side and the image side. Besides, we present the principle to measure length in object side from image. Secondly, we use LK optical flow which support pyramid data to track the ice in motion. Combining the result of camera calibration and single view metrology, we propose a flow to calculate the real velocity of ice flood. At last we realize a prototype system by programming and use it to test the reliability and rationality of the whole solution.

  3. Vibrating property of single Ge based heterostructure nanowires

    NASA Astrophysics Data System (ADS)

    Zhang, Yao; Wang, Chunrui; Xu, Jing

    2013-12-01

    Raman spectrum of single heterostructure nanowire can reflect its unusual lattice vibrations as well as the junction features. In this paper, we report Raman spectra of two morphologies of single Ge based heterostructure nanowire, that is, one is CdSe/Ge biaxial heterostructure nanowires(sample I), another is Ge nanowires is surrounded by CdSe nanoparticles (sample II), which is fabricated by one step thermal evaporation of CdSe and Ge powder. A new mode was observed in Raman spectrum of Ge nanowires surrounded by CdSe nanoparticles, which caused by the interaction of LO mode of CdSe and LO (TO) mode of Ge. The LO (TO) mode of Ge nanowire in CdSe/Ge biaxial heterostructure nanowires and Ge nanowires surrounded by CdSe nanoparticles all has a red-shift in comparison with that of Ge nanowires. The vibrational mode of CdSe in CdSe/Ge biaxial heterostructure nanowires has a red-shift. The vibrational mode of CdSe in Ge nanowires surrounded by CdSe nanoparticles has a blue-shift. The red-shift mode may be caused by quantum confinement effect. The blue-shift mode may be originated from tensile stress or high density of stacking defects. The vibrating mode of the heterostructure nanowires was much sensitive to stacking fault than to quantum confinement effect when the diameter of nanowire is larger than 300nm.

  4. 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

  5. A crystallographic model for nickel base single crystal alloys

    NASA Technical Reports Server (NTRS)

    Dame, L. T.; Stouffer, D. C.

    1988-01-01

    The purpose of this research is to develop a tool for the mechanical analysis of nickel-base single-crystal superalloys, specifically Rene N4, used in gas turbine engine components. This objective is achieved by developing a rate-dependent anisotropic constitutive model and implementing it in a nonlinear three-dimensional finite-element code. The constitutive model is developed from metallurgical concepts utilizing a crystallographic approach. An extension of Schmid's law is combined with the Bodner-Partom equations to model the inelastic tension/compression asymmetry and orientation-dependence in octahedral slip. Schmid's law is used to approximate the inelastic response of the material in cube slip. The constitutive equations model the tensile behavior, creep response and strain-rate sensitivity of the single-crystal superalloys. Methods for deriving the material constants from standard tests are also discussed. The model is implemented in a finite-element code, and the computed and experimental results are compared for several orientations and loading conditions.

  6. 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

  7. 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.

  8. Photoacoustic bio-quantification of graphene based nanomaterials at a single cell level (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Nedosekin, Dmitry A.; Nolan, Jacqueline; Biris, Alexandru S.; Zharov, Vladimir P.

    2017-03-01

    Arkansas Nanomedicine Center at the University of Arkansas for Medical Sciences in collaboration with other Arkansas Universities and the FDA-based National Center of Toxicological Research in Jefferson, AR is developing novel techniques for rapid quantification of graphene-based nanomaterials (GBNs) in various biological samples. All-carbon GBNs have wide range of potential applications in industry, agriculture, food processing and medicine; however, quantification of GBNs is difficult in carbon reach biological tissues. The accurate quantification of GBNs is essential for research on material toxicity and the development of GBNs-based drug delivery platforms. We have developed microscopy and cytometry platforms for detection and quantification of GBNs in single cells, tissue and blood samples using photoacoustic contrast of GBNs. We demonstrated PA quantification of individual graphene uptake by single cells. High-resolution PA microscopy provided mapping of GBN distribution within live cells to establish correlation with intracellular toxic phenomena using apoptotic and necrotic assays. This new methodology and corresponding technical platform provide the insight on possible toxicological risks of GBNs at singe cells levels. In addition, in vivo PA image flow cytometry demonstrated the capability to monitor of GBNs pharmacokinetics in mouse model and to map the resulting biodistribution of GBNs in mouse tissues. The integrated PA platform provided an unprecedented sensitivity toward GBNs and allowed to enhance conventional toxicology research by providing a direct correlation between uptake of GBNs at a single cell level and cell viability status.

  9. SuSPect: Enhanced Prediction of Single Amino Acid Variant (SAV) Phenotype Using Network Features

    PubMed Central

    Yates, Christopher M.; Filippis, Ioannis; Kelley, Lawrence A.; Sternberg, Michael J.E.

    2014-01-01

    Whole-genome and exome sequencing studies reveal many genetic variants between individuals, some of which are linked to disease. Many of these variants lead to single amino acid variants (SAVs), and accurate prediction of their phenotypic impact is important. Incorporating sequence conservation and network-level features, we have developed a method, SuSPect (Disease-Susceptibility-based SAV Phenotype Prediction), for predicting how likely SAVs are to be associated with disease. SuSPect performs significantly better than other available batch methods on the VariBench benchmarking dataset, with a balanced accuracy of 82%. SuSPect is available at www.sbg.bio.ic.ac.uk/suspect. The Web site has been implemented in Perl and SQLite and is compatible with modern browsers. An SQLite database of possible missense variants in the human proteome is available to download at www.sbg.bio.ic.ac.uk/suspect/download.html. PMID:24810707

  10. SuSPect: enhanced prediction of single amino acid variant (SAV) phenotype using network features.

    PubMed

    Yates, Christopher M; Filippis, Ioannis; Kelley, Lawrence A; Sternberg, Michael J E

    2014-07-15

    Whole-genome and exome sequencing studies reveal many genetic variants between individuals, some of which are linked to disease. Many of these variants lead to single amino acid variants (SAVs), and accurate prediction of their phenotypic impact is important. Incorporating sequence conservation and network-level features, we have developed a method, SuSPect (Disease-Susceptibility-based SAV Phenotype Prediction), for predicting how likely SAVs are to be associated with disease. SuSPect performs significantly better than other available batch methods on the VariBench benchmarking dataset, with a balanced accuracy of 82%. SuSPect is available at www.sbg.bio.ic.ac.uk/suspect. The Web site has been implemented in Perl and SQLite and is compatible with modern browsers. An SQLite database of possible missense variants in the human proteome is available to download at www.sbg.bio.ic.ac.uk/suspect/download.html. Copyright © 2014. Published by Elsevier Ltd.

  11. A microfluidic-based hydrodynamic trap for single particles.

    PubMed

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

    2011-01-21

    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. Avidity-mediated enhancement of in vivo tumor targeting by single-chain Fv dimers.

    PubMed

    Adams, Gregory P; Tai, Mei-Sheng; McCartney, John E; Marks, James D; Stafford, Walter F; Houston, L L; Huston, James S; Weiner, Louis M

    2006-03-01

    Radiolabeled single-chain Fv (sFv) molecules display highly specific tumor retention in the severe combined immunodeficient (SCID) mouse model; however, the absolute quantity of sFv retained in the tumors is diminished by the rapid renal elimination resulting from the small size of the sFv molecules (Mr 27,000) and by dissociation of the monovalent sFv from tumor-associated antigen. We previously reported significant improvement in tumor retention without a loss of targeting specificity on converting monovalent sFv into divalent [(sFv')2] dimers, linked by a disulfide bond between COOH-terminal cysteinyl peptides engineered into the sFv'. However, our data for enhanced dimer localization in tumors could not distinguish between the contributions of enhanced avidity and increased systemic retention associated with the larger size of 54 kDa [(sFv')2] dimers relative to 27-kDa sFv. In this investigation, we have compared tumor targeting of divalent anti-c-erbB-2/HER2/neu 741F8-1 (sFv')2 homodimers with monovalent 741F8/26-10 (sFv')2 heterodimers (Mr 54,000) and 741F8 sFv monomers (741F8 sFv has binding specificity for erbB-2/HER2/neu and 26-10 sFv specificity for digoxin and related cardiac glycosides). These studies allowed us to distinguish the dominant effect of valency over molecular weight in accounting for the superior tumor retention of 741F8-1 (sFv')2 homodimers. Each of the radioiodinated species was administered i.v. to SCID mice bearing SK-OV-3 human tumor xenografts and tumor localization at 24 hours post i.v. injection was determined for 125I-741F8-1 (sFv')2 (3.57 %ID/g), 125I-741F8/26-10 (sFv')2 (1.13 %ID/g), and 125I-741F8-1 sFv (1.25 %ID/g). These findings substantiate that the improved tumor retention of (sFv')2 homodimers over sFv monomers results from the availability of dual binding sites rather than from the slower systemic clearance of homodimers.

  13. 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.

  14. 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.

  15. 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

  16. Haplotyping a single triploid individual based on genetic algorithm.

    PubMed

    Wu, Jingli; Chen, Xixi; Li, Xianchen

    2014-01-01

    The minimum error correction model is an important combinatorial model for haplotyping a single individual. In this article, triploid individual haplotype reconstruction problem is studied by using the model. A genetic algorithm based method GTIHR is presented for reconstructing the triploid individual haplotype. A novel coding method and an effectual hill-climbing operator are introduced for the GTIHR algorithm. This relatively short chromosome code can lead to a smaller solution space, which plays a positive role in speeding up the convergence process. The hill-climbing operator ensures algorithm GTIHR converge at a good solution quickly, and prevents premature convergence simultaneously. The experimental results prove that algorithm GTIHR can be implemented efficiently, and can get higher reconstruction rate than previous algorithms.

  17. Optical Sensor Based on a Single CdS Nanobelt

    PubMed Central

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

    2014-01-01

    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. PMID:24763211

  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. 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

  20. Development and optimization of SERS-based immuno-nanosensor for single cell analyses

    NASA Astrophysics Data System (ADS)

    Li, Honggang; Cullum, Brian M.

    2004-03-01

    Surface enhanced Raman scattering (SERS) is an extremely sensitive and selective spectroscopic technique commonly employed for trace environmental analyses. We are currently developing and optimizing novel SERS based immuno-nanosensors for the monitoring of protein expression within individual living cells. These sensors, based upon antibody bound, silver coated silica nanospheres, can be inserted into individual cells and non-invasively positioned to the subcellular location of interest using optical tweezers. Because a HeNe laser is used for excitation, both photodamage to cells and cellular autofluorescence are minimized. Fabrication of the nanosensors is performed by first depositing a thin layer of silver on silica nanospheres by either homogeneous chemical deposition or vapor deposition. This is followed by binding an antibody against the analyte of interest to the sensor"s surface. In this paper we have investigated and optimized the reduction conditions of a chemical deposition substrate fabrication method and have compared these substrates to three types of vapor deposited substrates: (1) single layer silver film over nanosphere (SFON), (2) dual layer silver film over nanosphere (DUAL-FON) substrates (produced by coating an additional layer of silver film over the SFON), and (3) multilayer silver film over nanosphere (MULTI-FON) substrates (prepared by repeated coatings of several silver films over a SFON). In the case of chemical deposition, parameters optimized included silver nitrate concentration, reaction temperature, and silver coating time of substrates. In general, we have found SFON substrates yield better signal-to-noise ratios (S/N) with less background than the optimized, chemically prepared substrates. Even greater SERS enhancements have been found using multilayered SERS substrates (i.e., DUAL-FON substrates and MULTI-FON substrates). Both the stability and S/N of these substrates are enhanced by using multiple silver layers compared to SFON

  1. Magnetism of phthalocyanine-based organometallic single porous sheet.

    PubMed

    Zhou, Jian; Sun, Qiang

    2011-09-28

    A two-dimensional (2D) periodic Fe phthalocyanine (FePc) single-layer sheet has very recently been synthesized experimentally (Abel, M.; et al. J. Am. Chem. Soc.2011, 133, 1203), providing a novel pathway for achieving 2D atomic sheets with regularly and separately distributed transition-metal atoms for unprecedented applications. Here we present first-principles calculations based on density functional theory to investigate systematically the electronic and magnetic properties of such novel organometallics (labeled as TMPc, TM = Cr-Zn) as free-standing sheets. Among them, we found that only the 2D MnPc framework is ferromagnetic, while 2D CrPc, FePc, CoPc, and CuPc are antiferromagnetic and 2D NiPc and ZnPc are nonmagnetic. The difference in magnetic couplings for the studied systems is related to the different orbital interactions. Only MnPc displays metallic d(xz) and d(yz) orbitals that can hybridize with p electrons of Pc, which mediates the long-range ferromagnetic coupling. Monte Carlo simulations based on the Ising model suggest that the Curie temperature (T(C)) of the 2D MnPc framework is ∼150 K, which is comparable to the highest T(C) achieved experimentally, that of Mn-doped GaAs. The present study provides theoretical insight leading to a better understanding of novel phthalocyanine-based 2D structures beyond graphene and BN sheets.

  2. Enhancing durability of wood-based composites with nanotechnology

    Treesearch

    Carol Clausen

    2012-01-01

    Wood protection systems are needed for engineered composite products that are susceptible to moisture and biodeterioration. Protection systems using nano-materials are being developed to enhance the durability of wood-based composites through improved resistance to biodeterioration, reduced environmental impact from chemical leaching, and improved resistance to...

  3. SFM signal parameter estimation based on an enhanced DSFMT algorithm

    NASA Astrophysics Data System (ADS)

    Chen, Lei; Li, Xingguang; Chen, Dianren

    2017-01-01

    It is proposed a SFM signal parameter estimation method based on the Enhanced DSFMT(EDSFMT) algorithm and provided the derivation of transformation formulas in this paper .Analysis and simulations were performed, which proved its capability of arbitrary multi-component SFM signal parameter estimation.

  4. A model for single and multiple knowledge based networks.

    PubMed

    Bologna, G

    2003-06-01

    The inherent black-box nature of neural networks is an important drawback with respect to the problem of explanation of neural network responses. Although several articles have tackled the problem of rule extraction from a single neural network, just a few papers have investigated rule extraction from several combined neural networks. In this article we describe how to translate symbolic rules into the Discretized Interpretable Multi-Layer Perceptron (DIMLP) and how to extract rules from one or several combined neural networks. Our approach consists of characterizing discriminant hyperplane frontiers. Unordered rules are extracted in polynomial time with respect to the size of the problem and the size of the network. Moreover, the degree of matching between extracted rules and neural network responses is 100% on training examples. We applied single DIMLP networks to 17 data sets related to medical diagnosis and medical prognosis problems. Results based on 10-fold cross-validation showed that the DIMLP model was on average as accurate as standard multi-layer perceptrons (MLP). Furthermore, DIMLP networks were significantly more accurate than CN2 on eight problems, whereas only on one problem CN2 was better than DIMLP. Finally, a non-Hodgkin lymphoma diagnosis problem based on classification of electrophoresis gels was defined. It turned out that ensembles of DIMLP networks were significantly more accurate than CN2 (96.1% +/- 1.4 versus 82.7% +/- 4.0). Finally, symbolic rules revealed the presence of five important spots for the discrimination of the class of Lymphocyte Leukemia/Chronic Lymphoid Leukemia (Lc/LLc), and the class of Centrocytic Lymphoma (Cc).

  5. 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.

  6. Enhanced consumer goal achievement through strengths-based group supervision.

    PubMed

    Rapp, Charles A; Goscha, Richard J; Fukui, Sadaaki

    2015-09-01

    This article seeks to enhance and support consumer-centered care in psychiatric rehabilitation through the use of strengths-based group supervision (SBGS). The article is based on social science research findings, 30 years of experience with the model, and the literature on supervision. Relevant findings from research on the model are included. SBGS is a promising approach for improving consumer goal achievement and centeredness. It warrants further implementation and research. (c) 2015 APA, all rights reserved).

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

    SciTech Connect

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

    2013-06-21

    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 Multiplication-Sign 10{sup -9} s) at lower energies. Microstructural studies, conducted by X-ray diffraction ({theta}-2{theta} and {phi} 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 > Double-Vertical-Line Double-Vertical-Line c-YSZ<001> and in-plane NiO<110> Double-Vertical-Line Double-Vertical-Line 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{sup -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

  8. 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.

  9. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

    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 Ni50.0Mn28.5Ga21.5 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.

  11. 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.

  12. Carboplatin enhances the production and persistence of radiation-induced DNA single-strand breaks

    SciTech Connect

    Yang, L.; Douple, E.B.; O`Hara, J.A.; Wang, H.J.

    1995-09-01

    Fluorometric analysis of DNA unwinding and alkaline elution were used to investigate the production and persistence of DNA single-strand breaks (SSBs) in Chinese hamster V79 and xrs-5 cells treated with the chemotherapeutic agent carboplatin in combination with radiation. Carboplatin was administered to cells before irradiation in hypoxic conditions, or the drug was added immediately after irradiation during the postirradiation recovery period in air. The results of DNA unwinding studies suggest that carboplatin enhances the production of radiation-induced SSBs in hypoxic V79 cells and xrs-5 cells by a factor of 1.86 and 1.83, respectively, when combined with radiation compared to the SSBs produced by irradiation alone. Carboplatin alone did not produce a measureable number of SSBs. Alkaline elution profiles also indicated that the rate of elution of SSBs was higher in cells treated with the carboplatin is present after irradiation and during the postirradiation recovery period, the rejoining of radiation-induced SSBs by a factor of 1.46 in V79 cells with 20 Gy irradiation and by a factor of 2.02 in xrs-5 cells with 20 Gy irradiation. When carboplatin is present after irradiation and during the postirradiation recovery period, the rejoining of radiation-induced SSBs is inhibited during this postirradiation incubation period (radiopotentiation) with a relative inhibition factor at 1 h postirradiation of 1.25 in V79 cells and 1.15 in xrs-5 cells. An increased production and persistence of SSBs resulting from the interaction of carboplatin with radiation may be an important step in the mechanism responsible for the potentiated cell killing previously from studies in animal tumors and in cultured cells. 31 refs., 7 figs.

  13. Enhancing Stability of Camelid and Shark Single Domain Antibodies: An Overview

    PubMed Central

    Goldman, Ellen R.; Liu, Jinny L.; Zabetakis, Dan; Anderson, George P.

    2017-01-01

    Single domain antibodies (sdAbs) are gaining a reputation as superior recognition elements as they combine the advantages of the specificity and affinity found in conventional antibodies with high stability and solubility. Melting temperatures (Tms) of sdAbs cover a wide range from below 50 to over 80°C. Many sdAbs have been engineered to increase their Tm, making them stable until exposed to extreme temperatures. SdAbs derived from the variable heavy chains of camelid and shark heavy chain-only antibodies are termed VHH and VNAR, respectively, and generally exhibit some ability to refold and bind antigen after heat denaturation. This ability to refold varies from 0 to 100% and is a property dependent on both intrinsic factors of the sdAb and extrinsic conditions such as the sample buffer ionic strength, pH, and sdAb concentration. SdAbs have also been engineered to increase their solubility and refolding ability, which enable them to function even after exposure to temperatures that exceed their melting point. In addition, efforts to improve their stability at extreme pH and in the presence of chemical denaturants or proteases have been undertaken. Multiple routes have been employed to engineer sdAbs with these enhanced stabilities. The methods utilized to achieve these goals include grafting complementarity-determining regions onto stable frameworks, introduction of non-canonical disulfide bonds, random mutagenesis combined with stringent selection, point mutations such as inclusion of negative charges, and genetic fusions. Increases of up to 20°C have been realized, pushing the Tm of some sdAbs to over 90°C. Herein, we present an overview of the work done to stabilize sdAbs derived from camelids and sharks. Utilizing these various strategies sdAbs have been stabilized without significantly compromising their affinity, thereby providing superior reagents for detection, diagnostic, and therapeutic applications. PMID:28791022

  14. Single photon emission based on coherent state preparation

    NASA Astrophysics Data System (ADS)

    Ester, P.; Lackmann, L.; Michaelis de Vasconcellos, S.; Hübner, M. C.; Zrenner, A.; Bichler, M.

    2007-09-01

    The authors report here on deterministic single photon emission after coherent optical state preparation in the p-shell of a single InGaAs /GaAs quantum dot. In the approach, they use p-shell Rabi flopping followed by relaxation to the s-shell ground state with subsequent spontaneous single photon emission. Pulsed photon correlation experiments show complete suppression of the correlation peak at zero time delay and hence demonstrate clean single photon emission.

  15. 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.

  16. Sonoclot(®)-based method to detect iron enhanced coagulation.

    PubMed

    Nielsen, Vance G; Henderson, Jon

    2016-07-01

    Thrombelastographic methods have been recently introduced to detect iron mediated hypercoagulability in settings such as sickle cell disease, hemodialysis, mechanical circulatory support, and neuroinflammation. However, these inflammatory situations may have heme oxygenase-derived, coexistent carbon monoxide present, which also enhances coagulation as assessed by the same thrombelastographic variables that are affected by iron. This brief report presents a novel, Sonoclot-based method to detect iron enhanced coagulation that is independent of carbon monoxide influence. Future investigation will be required to assess the sensitivity of this new method to detect iron mediated hypercoagulability in clinical settings compared to results obtained with thrombelastographic techniques.

  17. Dual-chamber versus single-chamber detection enhancements for implantable defibrillator rhythm diagnosis: the detect supraventricular tachycardia study.

    PubMed

    Friedman, Paul A; McClelland, Robyn L; Bamlet, William R; Acosta, Helbert; Kessler, David; Munger, Thomas M; Kavesh, Neal G; Wood, Mark; Daoud, Emile; Massumi, Ali; Schuger, Claudio; Shorofsky, Stephen; Wilkoff, Bruce; Glikson, Michael

    2006-06-27

    Delivery of inappropriate shocks caused by misdetection of supraventricular tachycardia (SVT) remains a substantial complication of implanted cardioverter/defibrillator (ICD) therapy. Whether use of optimally programmed dual-chamber ICDs lowers this risk compared with that in single-chamber ICDs is not clear. Subjects with a clinical indication for ICD (n=400) at 27 participating centers received dual-chamber ICDs and were randomly assigned to strictly defined optimal single- or dual-chamber detection in a single-blind manner. Programming minimized ventricular pacing. The primary end point was the proportion of SVT episodes inappropriately detected from the time of programming until crossover or end of study. On a per-episode basis, 42% of the episodes in the single-chamber arm and 69% of the episodes in the dual-chamber arm were due to SVT. Mortality (3.5% in both groups) and early study withdrawal (14% single-chamber, 11% dual-chamber) were similar in both groups. The rate of inappropriate detection of SVT was 39.5% in the single-chamber detection arm compared with 30.9% in the dual-chamber arm. The odds of inappropriate detection were decreased by almost half with the use of the dual-chamber detection enhancements (odds ratio, 0.53; 95% confidence interval, 0.30 to 0.94; P=0.03). Dual-chamber ICDs, programmed to optimize detection enhancements and to minimize ventricular pacing, significantly decrease inappropriate detection.

  18. Sparse representation-based ECG signal enhancement and QRS detection.

    PubMed

    Zhou, Yichao; Hu, Xiyuan; Tang, Zhenmin; Ahn, Andrew C

    2016-12-01

    Electrocardiogram (ECG) signal enhancement and QRS complex detection is a critical preprocessing step for further heart disease analysis and diagnosis. In this paper, we propose a sparse representation-based ECG signal enhancement and QRS complex detection algorithm. Unlike traditional Fourier or wavelet transform-based methods, which use fixed bases, the proposed algorithm models the ECG signal as the superposition of a few inner structures plus additive random noise, where these structures (referred to here as atoms) can be learned from the input signal or a training set. Using these atoms and their properties, we can accurately approximate the original ECG signal and remove the noise and other artifacts such as baseline wandering. Additionally, some of the atoms with larger kurtosis values can be modified and used as an indication function to detect and locate the QRS complexes in the enhanced ECG signals. To demonstrate the robustness and efficacy of the proposed algorithm, we compare it with several state-of-the-art ECG enhancement and QRS detection algorithms using both simulated and real-life ECG recordings.

  19. 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.

  20. 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.

  1. 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.

  2. Compact Q-value enhanced bandpass filter based on the EIT-like effect accompanying application in downconversion APL.

    PubMed

    Yu, Hongchen; Chen, Minghua; Li, Pengxiao; Yang, Sigang; Chen, Hongwei; Xie, Shizhong

    2013-10-01

    A compact quality factor (Q)-enhanced bandpass filter based on the electromagnetically induced transparency (EIT)-like effect between two-ring resonators was proposed and experimental demonstrated. The enhancement in Q can be 2-3 orders of magnitude compared to the single ring bandpass filter, and a 27 times enhanced bandpass filter with a bandwidth of approximately 4.8 GHz was successfully realized. A downconversion analog photonic link (APL) based on the proposed filter has been presented and the spurious free dynamic range of the link was as high as 103.9 dB-Hz(2/3).

  3. Physics-based analytical model for ferromagnetic single electron transistor

    NASA Astrophysics Data System (ADS)

    Jamshidnezhad, K.; Sharifi, M. J.

    2017-03-01

    A physically based compact analytical model is proposed for a ferromagnetic single electron transistor (FSET). This model is based on the orthodox theory and solves the master equation, spin conservation equation, and charge neutrality equation simultaneously. The model can be applied to both symmetric and asymmetric devices and does not introduce any limitation on the applied bias voltages. This feature makes the model suitable for both analog and digital applications. To verify the accuracy of the model, its results regarding a typical FSET in both low and high voltage regimes are compared with the existing numerical results. Moreover, the model's results of a parallel configuration FSET, where no spin accumulation exists in the island, are compared with the results obtained from a Monte Carlo simulation using SIMON. These two comparisons show that our model is valid and accurate. As another comparison, the model is compared analytically with an existing model for a double barrier ferromagnetic junction (having no gate). This also verifies the accuracy of the model.

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

    PubMed

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

    2016-09-02

    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.

  5. Enhancements to the KATE model-based reasoning system

    NASA Technical Reports Server (NTRS)

    Thomas, Stan J.

    1994-01-01

    KATE (Knowledge-based Autonomous Test Engineer) is a model-based software system developed in the Artificial Intelligence Laboratory at the Kennedy Space Center for monitoring, fault detection, and control of launch vehicles and ground support systems. This report describes two software efforts which enhance the functionality and usability of KATE. The first addition, a flow solver, adds to KATE a tool for modeling the flow of liquid in a pipe system. The second addition adds support for editing KATE knowledge base files to the Emacs editor. The body of this report discusses design and implementation issues having to do with these two tools. It will be useful to anyone maintaining or extending either the flow solver or the editor enhancements.

  6. Colorimetry-based edge preservation approach for color image enhancement

    NASA Astrophysics Data System (ADS)

    Suresh, Merugu; Jain, Kamal

    2016-07-01

    "Subpixel-based downsampling" is an approach that can implicitly enhance perceptible image resolution of a downsampled image by managing subpixel-level representation preferably with individual pixel. A subpixel-level representation for color image sample at edge region and color image representation is focused with the problem of directional filtration based on horizontal and vertical orientations using colorimetric color space with the help of saturation and desaturation pixels. A diagonal tracing algorithm and an edge preserving approach with colorimetric color space were used for color image enhancement. Since, there exist high variations at the edge regions, it could not be considered as constant or zero, and when these variations are random the need to compensate these to minimum value and then process for image representation. Finally, the results of the proposed method show much better image information as compared with traditional direct pixel-based methods with increased luminance and chrominance resolutions.

  7. Enhancing intestinal drug solubilisation using lipid-based delivery systems.

    PubMed

    Porter, Christopher J H; Pouton, Colin W; Cuine, Jean F; Charman, William N

    2008-03-17

    Lipid-based delivery systems are finding increasing application in the oral delivery of poorly water-soluble, lipophilic drugs. Whilst lipidic dose forms may improve oral bioavailability via several mechanisms, enhancement of gastrointestinal solubilisation remains argueably the most important method of absorption enhancement. This review firstly describes the mechanistic rationale which underpins the use of lipid-based delivery systems to enhance drug solubilisation and briefly reviews the available literature describing increases in oral bioavailability after the administration of lipid solution, suspension and self-emulsifying formulations. The use of in vitro methods including dispersion tests and more complex models of in vitro lipolysis as indicators of potential in vivo performance are subsequently described, with particular focus on recent data which suggests that the digestion of surfactants present in lipid-based formulations may impact on formulation performance. Finally, a series of seven guiding principles for formulation design of lipid-based delivery systems are suggested based on an analysis of recent data generated in our laboratories and elsewhere.

  8. Efficient single-photon source based on a deterministically fabricated single quantum dot - microstructure with backside gold mirror

    NASA Astrophysics Data System (ADS)

    Fischbach, Sarah; Kaganskiy, Arsenty; Tauscher, Esra Burcu Yarar; Gericke, Fabian; Thoma, Alexander; Schmidt, Ronny; Strittmatter, André; Heindel, Tobias; Rodt, Sven; Reitzenstein, Stephan

    2017-07-01

    We present an efficient broadband single-photon source which is fabricated by a flip-chip gold-bonding technique and in-situ electron beam lithography. The device comprises a single InGaAs quantum dot that is centered at the bottom of a monolithic mesa structure and located above a gold mirror for enhanced photon-extraction efficiency. We show a photon-extraction efficiency of ηex t=(18 ±2 ) % into a numerical aperture of 0.4 and a high suppression of multi-photon events from this source with g(2 )(0 )=0.015 ±0.009 . Our deterministic device with a backside gold mirror can be combined with electrical contacts and piezo-tuning capabilities in future refinements, which represents an important step towards a spectrally tunable plug-and-play quantum-light source with broadband enhancement for photonic quantum networks.

  9. Single-session transcranial direct current stimulation induces enduring enhancement of visual processing speed in patients with major depression.

    PubMed

    Gögler, Nadine; Willacker, Lina; Funk, Johanna; Strube, Wolfgang; Langgartner, Simon; Napiórkowski, Natan; Hasan, Alkomiet; Finke, Kathrin

    2016-12-30

    Attentional deficits are considered key cognitive symptoms in major depressive disorder (MDD) arising from abnormal activation patterns within dorsolateral prefrontal cortex (dlPFC) alertness networks. Altering these activity patterns with transcranial direct current stimulation (tDCS) might thus ameliorate alertness-dependent cognitive deficits in MDD patients. In a double-blind, randomized, sham-controlled study, we investigated the effect of a single session of anodal tDCS (2 mA) applied to the left dlPFC on different parameters of visual attention based on Bundesen's theory of visual attention (Psychol Rev 97(4):523-547, 1990) in a group of 20 patients with MDD and a control group of 20 healthy participants. The parametric attention assessment took place before, immediately after and 24 h after tDCS intervention. It revealed a selective impairment in visual processing speed as a primary functional deficit in MDD at baseline assessment. Furthermore, a significant stimulation condition × time point interaction showed that verum tDCS over the left dlPFC resulted in a processing speed enhancement 24 h post-stimulation in MDD patients. In healthy control participants, we did not find similar tDCS-induced effects. Our results suggest that even a single session of tDCS over the dlPFC can induce enduring neurocognitive benefits that indicate an amelioration of cortical under-arousal in MDD patients in a time frame beyond that of immediate, excitability increases that are directly induced by the current.

  10. 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

  11. Evolution-operator-based single-step method for image processing.

    PubMed

    Sun, Yuhui; 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.

  12. Infrared image detail enhancement based on the gradient field specification.

    PubMed

    Zhao, Wenda; Xu, Zhijun; Zhao, Jian; Zhao, Fan; Han, Xizhen

    2014-07-01

    Human vision is sensitive to the changes of local image details, which are actually image gradients. To enhance faint infrared image details, this article proposes a gradient field specification algorithm. First we define the image gradient field and gradient histogram. Then, by analyzing the characteristics of the gradient histogram, we construct a Gaussian function to obtain the gradient histogram specification and therefore obtain the transform gradient field. In addition, subhistogram equalization is proposed based on the histogram equalization to improve the contrast of infrared images. The experimental results show that the algorithm can effectively improve image contrast and enhance weak infrared image details and edges. As a result, it can give qualified image information for different applications of an infrared image. In addition, it can also be applied to enhance other types of images such as visible, medical, and lunar surface.

  13. Infrared small target enhancement based on variance difference

    NASA Astrophysics Data System (ADS)

    Nasiri, Mahdi; Chehresa, Saeed

    2017-05-01

    In surveillance and early warning systems, the enhancement of targets is a very important stage for the high reliability detection and tracking in Infrared images with complex backgrounds. In order to enhance small targets in an Infrared image and suppress the background clutter, consequently increasing the contrast between them, this paper proposes a method using a model for the target area with a three-layer patch-image model and based on the difference between the variance of the layers in the neighboring areas of the investigated pixel. Results of the experiments indicate that the proposed method is quite effective on the enhancement of small targets as well as suppression of the background clutter in IR images with a minimum false alarm rate. This is realized while the runtime of the proposed method is minimal compared to other commonly used methods, which makes it effective to be used in real time applications.

  14. Unsupervised abnormality detection using saliency and Retinex based color enhancement.

    PubMed

    Deeba, Farah; Mohammed, Shahed K; Bui, Francis M; Wahid, Khan A

    2016-08-01

    An efficient and automated abnormality detection method can significantly reduce the burden of screening of the enormous visual information resulting from capsule endoscopic procedure. As a pre-processing stage, color enhancement could be useful to improve the image quality and the detection performance. Therefore, in this paper, we have proposed a two-stage automated abnormality detection algorithm. In the first stage, an adaptive color enhancement method based on Retinex theory is applied on the endoscopic images. In the second stage, an efficient salient region detection algorithm is applied to detect the clinically significant regions. The proposed algorithm is applied on a dataset containing images with diverse pathologies. The algorithm can successfully detect a significant percentage of the abnormal regions. From our experiment, it was evident that color enhancement method improves the performance of abnormality detection. The proposed algorithm can achieve a sensitivity of 97.33% and specificity of 79%, higher than state-of-the-art performance.

  15. Model-based speech enhancement using a bone-conducted signal.

    PubMed

    Kechichian, Patrick; Srinivasan, Sriram

    2012-03-01

    Codebook-based single-microphone noise suppressors, which exploit prior knowledge about speech and noise statistics, provide better performance in nonstationary noise. However, as the enhancement involves a joint optimization over speech and noise codebooks, this results in high computational complexity. A codebook-based method is proposed that uses a reference signal observed by a bone-conduction microphone, and a mapping between air- and bone-conduction codebook entries generated during an offline training phase. A smaller subset of air-conducted speech codebook entries that accurately models the clean speech signal is selected using this reference signal. Experiments support the expected improvement in performance at low computational complexity.

  16. Enhanced single strand breaks of supercoiled DNA in a matrix of gold nanotubes under X-ray irradiation.

    PubMed

    Carter, Joshua D; Cheng, Neal N; Qu, Yongquan; Suarez, George D; Guo, Ting

    2012-07-15

    Single-strand-breaks (SSBs) of supercoiled DNA (scDNA) molecules were used to probe the enhancement of X-ray radiation effect on scDNA mixed with gold nanotubes (AuNTs) in water. The amounts of measured enhancements using SSBs were significantly lower than the expected increase in energy deposition in water by AuNTs under hard X-ray irradiation. Three factors were identified to negatively affect the enhancement: (1) Attenuation of kinetic energies carried by electrons escaped from AuNTs, (2) Scavenging of OH radicals (˙OH) by the surface of bare AuNTs, and (3) Steric effect due to soluble scDNA molecules away from the surface of AuNTs. Benefits and limits of using gold nanomaterials as radiation enhancers and contrast agents are discussed. Copyright © 2012 Elsevier Inc. All rights reserved.

  17. Enhanced thermoelectric performance of template based nanostructured polyaniline

    NASA Astrophysics Data System (ADS)

    Maity, Shilpa; Rakshit, Subhra; Das, Sukhen; Chatterjee, Krishanu

    2017-05-01

    Nanostructured polyaniline doped with organic dopant has been synthesized employing a template based in-situ polymerization. Spectral analysis of the sample shows a more ordered structure. The transport properties are carried out for thermoelectric applications which shows that the template based synthesis plays an important role to influence the electrical transport properties of PANI. This template based synthesis of nanostructured PANI is proposed for enhancement of figure of merit through an increase in the electrical conductivity and thermoelectric power and decrease in thermal conductivity. Compared to the earlier works the figure of merit evaluated is much higher.

  18. ZnO-based microrockets with light-enhanced propulsion.

    PubMed

    Dong, Renfeng; Wang, Chun; Wang, Qinglong; Pei, Allen; She, Xueling; Zhang, Yuxian; Cai, Yuepeng

    2017-10-12

    Improving the propulsion of artificial micro-nanomotors represents an exciting nanotechnology challenge, especially considering their cargo delivery ability and fuel efficiency. In light of the excellent photocatalytic performance of zinc oxide (ZnO) and chemical catalytic properties of platinum (Pt), ZnO-Pt microrockets with light-enhanced propulsion have been developed by atomic layer deposition (ALD) technology. The velocity of such microrockets is dramatically doubled upon irradiation by 77 mW cm(-2) ultraviolet (UV) light in 10% H2O2 and is almost 3 times higher than the classic poly(3,4-ethylenedioxythiophene)-Pt microrockets (PEDOT-Pt microrockets) even in 6% H2O2 under the same UV light. In addition, such micromotors not only retain the standard approach to improve propulsion by varying the fuel concentration, but also demonstrate a simple way to enhance the movement velocity by adjusting the UV light intensity. High reversibility and controllable "weak/strong" propulsion can be easily achieved by switching the UV irradiation on or off. Finally, light-enhanced propulsion has been investigated by electrochemical measurements which further confirm the enhanced photocatalytic properties of ZnO and Pt. The successful demonstration of ZnO-based microrockets with excellent light-enhanced propulsion is significant for developing highly efficient synthetic micro-nanomotors which have strong delivery ability and economic fuel requirements for future practical applications in the micro-nanoscale world.

  19. Sequence-dependent elasticity and electrostatics of single-stranded DNA: signatures of base-stacking.

    PubMed

    McIntosh, Dustin B; Duggan, Gina; Gouil, Quentin; Saleh, Omar A

    2014-02-04

    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. Copyright © 2014 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  20. 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.

  1. Use of Single-Layer g-C3N4/Ag Hybrids for Surface-Enhanced Raman Scattering (SERS).

    PubMed

    Jiang, Jizhou; Zou, Jing; Wee, Andrew Thye Shen; Zhang, Wenjing

    2016-09-30

    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.

  2. 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

  3. 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

  4. Ion-track based single-channel templates for single-nanowire contacting

    NASA Astrophysics Data System (ADS)

    Chtanko, N.; Toimil-Molares, M. E.; Cornelius, T. W.; Dobrev, D.; Neumann, R.

    2005-07-01

    This work reports a procedure for the fabrication of membranes containing only one single channel with diameter down to 20 nm and with well-defined geometry. Foils of different types of polymer (polyethylene terephthalate (PET) and polycarbonate (PC)) were tested with respect to their suitability as ion-track template for single-nanowire growth. Membranes with one pore were created by the track-etching technique. The pore size was characterized by electrical conductivity measurements in 1 M KCl. Furthermore, we developed also a method for the preparation and electrical contacting of single metallic nanowires. Cylindrical single pores were filled with Bi by electrochemical deposition. The resulting wires, remaining embedded in the polymer foil, are very suitable for measurements of electrical resistance as a function of parameters such as wire diameter and temperature.

  5. Spatially uniform enhancement of single quantum dot emission using plasmonic grating decoupler

    NASA Astrophysics Data System (ADS)

    Kumar, Arunandan; Weeber, Jean-Claude; Bouhelier, Alexandre; Eloi, Fabien; Buil, Stéphanie; Quélin, Xavier; Nasilowski, Michel; Dubertret, Benoit; Hermier, Jean-Pierre; Colas Des Francs, Gérard

    2015-11-01

    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.

  6. Effect of intermittent hypoxic training on hypoxia tolerance based on single-channel EEG.

    PubMed

    Zhang, Tinglin; Wang, You; Li, Guang

    2016-03-23

    A single-channel algorithm was proposed in order to study effect of intermittent hypoxic training on hypoxia tolerance based on EEG pattern. EEG was decomposed by ensemble empirical mode decomposition into a finite number of intrinsic mode functions (IMFs) based on the intrinsic local characteristic time scale. Analytic amplitude, analytic frequency, and recurrence property quantified by recurrence quantification analysis were explored on IMFs, and the first two scales revealed difference between normal EEG and hypoxia EEG. Classification accuracy of hypoxia EEG and normal EEG could reach 67.8% before decline of neurobehavioral ability, which represented that hypoxia EEG pattern could be detected at an early stage. Classification accuracy of hypoxia EEG and normal EEG increased with time and deepened intensity of hypoxia was observed by regular shift of hypoxia EEG pattern with time in a three dimensional subspace. The reduced shift and classification accuracy after intermittent hypoxic training represented that hypoxia tolerance enhanced.

  7. 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

  8. 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

    2015-11-25

    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.

  9. 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

  10. Infrared image enhancement based on human visual properties

    NASA Astrophysics Data System (ADS)

    Chen, Hongyu; Hui, Bin

    2015-10-01

    With the development of modern military, infrared imaging technology is widely used in this field. However, limited by the mechanism of infrared imaging and the detector, infrared images have the disadvantages of low contrast and blurry edge by comparison with the visible image. These shortcomings lead infrared image unsuitable to be observed by both human and computer. Thus image enhancement is required. Traditional image enhancement methods on the application of infrared image, without taking into account the human visual properties, is not convenient for the human observation. This article purposes a new method that combines the layering idea with the human visual properties to enhance the infrared image. The proposed method relies on bilateral filtering to separate a base component, which contains the large amplitude signal and must be compressed, from a detail component, which must be expanded because it contains the small signal variations related to fine texture. The base component is mapped into the proper range which is 8-bit using the human visual properties, and the detail component is applied the method of adaptive gain control. Finally, the two parts are recombined and quantized to 8-bit domain. Experimental results show that this algorithm exceeds most current image enhancement methods in solving the problems of low contrast and blurry detail.

  11. 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

  12. Anatomical noise in contrast-enhanced digital mammography. Part I. Single-energy imaging.

    PubMed

    Hill, Melissa L; Mainprize, James G; Carton, Ann-Katherine; Muller, Serge; Ebrahimi, Mehran; Jong, Roberta A; Dromain, Clarisse; Yaffe, Martin J

    2013-05-01

    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. A power law is used to model anatomical noise in CEDM images. The exponent, β, which describes the anatomical structure, and the constant α, 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 α and β are measured both from unprocessed images and from subtracted images. Consistent results were found between the two SE CEDM pilot studies, where a significant decrease in β from a value of approximately 3.1 in the unprocessed images to between about 1.1 and 1.8 in the subtracted images was observed. Increasing the x-ray energy from that used

  13. 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.

  14. 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.

  15. Enhanced thermoelectric performance of Bi2Te3 through uniform dispersion of single wall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Ahmad, Kaleem; Wan, Chunlei

    2017-10-01

    The advancement in nanostructured powder processing has attracted great interest as a cost effective and scalable strategy for high performance thermoelectric bulk materials. However, the level of technical breakthrough realized in quantum dot supperlattices/wires has not yet been demonstrated in these materials. Here, we report the first ever study on the uniform dispersion of single wall carbon nanotubes (SWCNTs) in nanostructured Bi2Te3 bulk, and their effect on thermoelectric parameters above room temperature. The Bi2Te3 based SWCNT composites were prepared through controlled powder processing, and their thermoelectric properties were finely tuned at the nanoscale by regulating various (0.5, 0.75, 1.0 and 1.5) vol% of SWCNTs in the matrix. The flexible ropes of SWCNT, making an interconnected network through the inter/trans granular positions of Bi2Te3, thus substantially change the transport properties of the composites. The perfect one-dimensional (1D) conducting structure of SWCNTs acts as a source of electrical transport through a percolating network, with significantly suppressed lattice thermal conductivity, via intensified boundary scattering. The remarkable increase in power factor is ascribed to energy filtering effects and excellent electrical transport of 1D SWCNTs in the composites. Consequently, with a considerable reduction in thermal conductivity, the figure of merit culminates in a several-fold improvement, at 0.5 vol% of SWCNTs, over pristine bulk Bi2Te3.

  16. Enhanced thermoelectric performance of Bi2Te3 through uniform dispersion of single wall carbon nanotubes.

    PubMed

    Ahmad, Kaleem; Wan, Chunlei

    2017-10-13

    The advancement in nanostructured powder processing has attracted great interest as a cost effective and scalable strategy for high performance thermoelectric bulk materials. However, the level of technical breakthrough realized in quantum dot supperlattices/wires has not yet been demonstrated in these materials. Here, we report the first ever study on the uniform dispersion of single wall carbon nanotubes (SWCNTs) in nanostructured Bi2Te3 bulk, and their effect on thermoelectric parameters above room temperature. The Bi2Te3 based SWCNT composites were prepared through controlled powder processing, and their thermoelectric properties were finely tuned at the nanoscale by regulating various (0.5, 0.75, 1.0 and 1.5) vol% of SWCNTs in the matrix. The flexible ropes of SWCNT, making an interconnected network through the inter/trans granular positions of Bi2Te3, thus substantially change the transport properties of the composites. The perfect one-dimensional (1D) conducting structure of SWCNTs acts as a source of electrical transport through a percolating network, with significantly suppressed lattice thermal conductivity, via intensified boundary scattering. The remarkable increase in power factor is ascribed to energy filtering effects and excellent electrical transport of 1D SWCNTs in the composites. Consequently, with a considerable reduction in thermal conductivity, the figure of merit culminates in a several-fold improvement, at 0.5 vol% of SWCNTs, over pristine bulk Bi2Te3.

  17. Single dielectric barrier discharge plasma enhanced aerodynamics: physics, modeling and applications

    NASA Astrophysics Data System (ADS)

    Corke, Thomas C.; Post, Martiqua L.; Orlov, Dmitriy M.

    2009-01-01

    The term “plasma actuator” has been a part of the fluid dynamics flow control vernacular for more than a decade. A particular type of plasma actuator that has gained wide use is based on a single dielectric barrier discharge (SDBD) mechanism that has desirable features for use in air at atmospheric pressures. For these actuators, the mechanism of flow control is through a generated body force vector that couples with the momentum in the external flow. The body force can be derived from first principles and the plasma actuator effect can be easily incorporated into flow solvers so that their placement and operation can be optimized. They have been used in a wide range of applications that include bluff body wake control; lift augmentation and separation control on a variety of lifting surfaces ranging from fixed wings with various degrees of sweep, wind turbine rotors and pitching airfoils simulating helicopter rotors; flow separation and tip-casing clearance flow control to reduce losses in turbines, to control flow surge and stall in compressors; and in exciting instabilities in boundary layers at subsonic to supersonic Mach numbers for turbulent transition control. New applications continue to appear through programs in a growing number of US universities and government laboratories, as well as in Germany, France, England, Netherland, Russia, Japan and China. This paper provides an overview of the physics, design and modeling of SDBD plasma actuators. It then presents their use in a number of applications that includes both numerical flow simulations and experiments together.

  18. Ultrasound image enhancement using structure-based filtering.

    PubMed

    Ueng, Shyh-Kuang; Yen, Cho-Li; Chen, Guan-Zhi

    2014-01-01

    Ultrasound images are prone to speckle noises. Speckles blur features which are essential for diagnosis and assessment. Thus despeckling is a necessity in ultrasound image processing. Linear filters can suppress speckles, but they smooth out features. Median filter based despeckling algorithms produce better results. However, they may produce artifact patterns in the resulted images and oversmooth nonuniform regions. This paper presents an innovative despeckle procedure for ultrasound images. In the proposed method, the diffusion tensor of intensity is computed at each pixel at first. Then the eigensystem of the diffusion tensor is calculated and employed to detect and classify the underlying structure. Based on the classification result, a feasible filter is selected to suppress speckles and enhance features. Test results show that the proposed despeckle method reduces speckles in uniform areas and enhances tissue boundaries and spots.

  19. Two RFID-based solutions to enhance inpatient medication safety.

    PubMed

    Chien, Hung-Yu; Yang, Chia-Chuan; Wu, Tzong-Chen; Lee, Chin-Feng

    2011-06-01

    Owing to the low cost and convenience of identifying an object without physical contact, Radio Frequency Identification (RFID) systems provide innovative, promising and efficient applications in many domains. An RFID grouping protocol is a protocol that allows an off-line verifier to collect and verify the evidence of two or more tags simultaneously present. Recently, Huang and Ku (J. Med. Syst, 2009) proposed an efficient grouping protocol to enhance medication safety for inpatients based on low-cost tags. However, the Huang-Ku scheme is not secure; an attacker can easily make up fake grouping records to cheat the verifier. This weakness would seriously endanger the safety of inpatient medication safety. This paper will show the weaknesses, and then propose two RFID-based solutions to enhance medication safety for two different scenarios. The proposed schemes are practical, secure and efficient for medication applications.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. Quantum coherence in Mn-based single molecule magnets

    NASA Astrophysics Data System (ADS)

    Abeywardana, C.; Cho, F. H.; Mowson, A.; Christou, G.; Takahashi, S.

    2015-03-01

    As spin systems in solids, single-molecule magnets (SMMs) form a unique class of materials that have a high-spin, and their spin state and interaction can be easily tuned by changing peripheral organic ligands and solvate molecules. In addition, it has been shown that an individual or a small ensemble of SMMs can be transferred to surface with retention of their magnetic behavior. SMM is therefore a promising system for fundamental quantum science and for applications to dense and efficient quantum memory, computing, and molecular spintronics devices. In spite of diverse interests on quantum properties in SMMs, decoherence properties that ultimately limit such behaviors have not been understood yet. Until now, coherent manipulation of spin states in SMMs has been experimentally demonstrated only in a few SMMs. In this presentation, we investigate quantum coherence in Mn-based SMMs using a high-frequency pulsed EPR technique, which has a significant advantage to quench the spin decoherence due to electron spins.

  5. Terahertz single-photon detectors based on quantum wells

    NASA Astrophysics Data System (ADS)

    Kajihara, Yusuke; Nakajima, Takashi; Wang, Zhihai; Komiyama, Susumu

    2013-04-01

    Semiconductor charge-sensitive infrared phototransistors (CSIPs) based on quantum wells are described. They are the only detectors that are able to count single photons in the terahertz region at present. In terms of the noise equivalent power (NEP), the detectors show experimental values of 7 × 10-20 W/Hz1/2, while theoretically expected values are even much lower. These NEP values are by several orders of magnitude lower than any other state-of-the-art highly sensitive detectors. In addition to the outstanding sensitivity, the detectors are featured by strong advantage of huge current responsivity (>1 × 105 A/W) and low output impedance (<10 kΩ). This excellent performance in the above has been obtained for λ = 12-28 μm. By introducing a modified scheme of detection (called "lateral-escape") along with an improved coupler structure (bowtie antenna), we have achieved similar excellent performance for 45 μm. The CSIP provides extremely promising detectors for a variety of applications covering a wide spectral range of 12-100 μm.

  6. 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.

  7. Hybrid edge and feature-based single-image superresolution

    NASA Astrophysics Data System (ADS)

    Islam, Mohammad Moinul; Islam, Mohammed Nazrul; Asari, Vijayan K.; Karim, Mohammad A.

    2016-07-01

    A neighborhood-dependent component feature learning method for regression analysis in single-image superresolution is presented. Given a low-resolution input, the method uses a directional Fourier phase feature component to adaptively learn the regression kernel based on local covariance to estimate the high-resolution image. The unique feature of the proposed method is that it uses image features to learn about the local covariance from geometric similarity between the low-resolution image and its high-resolution counterpart. For each patch in the neighborhood, we estimate four directional variances to adapt the interpolated pixels. This gives us edge information and Fourier phase gives features, which are combined to interpolate using kernel regression. In order to compare quantitatively with other state-of-the-art techniques, root-mean-square error and measure mean-square similarity are computed for the example images, and experimental results show that the proposed algorithm outperforms similar techniques available in the literature, especially at higher resolution scales.

  8. Transport properties of hectorite based nanocomposite single ion conductors

    NASA Astrophysics Data System (ADS)

    Singhal, Ruchi Gupta; Capracotta, Michael D.; Martin, James D.; Khan, Saad A.; Fedkiw, Peter S.

    The ionic conductivity and rheological properties of clay filled nanocomposite electrolytes are reported. These electrolytes, which have potential use in lithium-ion batteries, consist of lithium-exchanged hectorite, a 2:1 layered smectite clay, dispersed in ethylene carbonate (EC) or a mixture of EC+polyethylene glycol di-methyl ether (PEG-dm, 250 MW). All samples exhibit elastic, gel-like characteristics and room temperature conductivities of order 0.1 mS/cm. A maximum in conductivity is observed at about 25 wt.% clay concentration. A maximum in hectorite basal layer spacing is also observed in the same concentration range, suggesting a direct correlation between conductivity and layer spacing. The elastic modulus and yield stress increase by two orders of magnitude and the conductivity increases by one order of magnitude with increase in hectorite concentration from 5 to 25%, which indicates the significant influence of hectorite content in determining the characteristics of these single-ion conductors. The solvent composition plays a secondary role in this regard, with addition of PEG-dm to the base EC+hectorite electrolyte producing moderate improvement in conductivity. Similarly, the addition of PEG-dm to EC+hectorite affects an increase by only a factor of three in the elastic modulus and yield stress of the electrolyte.

  9. Single Wall Carbon Nanotubes Based Cryogenic Temperature Sensor Platforms.

    PubMed

    Monea, Bogdan Florian; Ionete, Eusebiu Ilarian; Spiridon, Stefan Ionut; Leca, Aurel; Stanciu, Anda; Petre, Emil; Vaseashta, Ashok

    2017-09-10

    We present an investigation consisting of single walled carbon nanotubes (SWCNTs) based cryogenic temperature sensors, capable of measuring temperatures in the range of 2-77 K. Carbon nanotubes (CNTs) due to their extremely small size, superior thermal and electrical properties have suggested that it is possible to create devices that will meet necessary requirements for miniaturization and better performance, by comparison to temperature sensors currently available on the market. Starting from SWCNTs, as starting material, a resistive structure was designed. Employing dropcast method, the carbon nanotubes were deposited over pairs of gold electrodes and in between the structure electrodes from a solution. The procedure was followed by an alignment process between the electrodes using a dielectrophoretic method. Two sensor structures were tested in cryogenic field down to 2 K, and the resistance was measured using a standard four-point method. The measurement results suggest that, at temperatures below 20 K, the temperature coefficient of resistance average for sensor 1 is 1.473%/K and for sensor 2 is 0.365%/K. From the experimental data, it can be concluded that the dependence of electrical resistance versus temperature can be approximated by an exponential equation and, correspondingly, a set of coefficients are calculated. It is further concluded that the proposed approach described here offers several advantages, which can be employed in the fabrication of a microsensors for cryogenic applications.

  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. 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.

  12. Ionogram trace enhancement based on image pixel connectedness

    NASA Astrophysics Data System (ADS)

    Lu, Hongguang; Ji, Guangrong; Zheng, Haiyong; Zhao, Zhenwei; He, Shaohong

    2013-07-01

    This paper proposes a novel idea for ionogram trace enhancement to obtain the "clean" ionogram with real ionospheric echo signals, which is very important for further ionogram interpretation and scaling manually or automatically. Two methods based on ionogram trace pixel connectedness are adopted: max filter and connected components labeling. The experiments show that both methods are feasible and effective, and parameter selection and time complexity of the two methods are analyzed.

  13. Enhancing seismic P phase arrival picking based on wavelet denoising and kurtosis picker

    NASA Astrophysics Data System (ADS)

    Shang, Xueyi; Li, Xibing; Weng, Lei

    2017-09-01

    P phase arrival picking of weak signals is still challenging in seismology. A wavelet denoising is proposed to enhance seismic P phase arrival picking, and the kurtosis picker is applied on the wavelet-denoised signal to identify P phase arrival. It has been called the WD-K picker. The WD-K picker, which is different from those traditional wavelet-based pickers on the basis of a single wavelet component or certain main wavelet components, takes full advantage of the reconstruction of main detail wavelet components and the approximate wavelet component. The proposed WD-K picker considers more wavelet components and presents a better P phase arrival feature. The WD-K picker has been evaluated on 500 micro-seismic signals recorded in the Chinese Yongshaba mine. The comparison between the WD-K pickings and manual pickings shows the good picking accuracy of the WD-K picker. Furthermore, the WD-K picking performance has been compared with the main detail wavelet component combining-based kurtosis (WDC-K) picker, the single wavelet component-based kurtosis (SW-K) picker, and certain main wavelet component-based maximum kurtosis (MMW-K) picker. The comparison has demonstrated that the WD-K picker has better picking accuracy than the other three-wavelet and kurtosis-based pickers, thus showing the enhanced ability of wavelet denoising.

  14. 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. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Detecting Chemically Modified DNA Bases Using Surface Enhanced Raman Spectroscopy.

    PubMed

    Barhoumi, Aoune; Halas, Naomi J

    2011-12-15

    Post-translational modifications of DNA- changes in the chemical structure of individual bases that occur without changes in the DNA sequence- are known to alter gene expression. They are believed to result in frequently deleterious phenotypic changes, such as cancer. Methylation of adenine, methylation and hydroxymethylation of cytosine, and guanine oxidation are the primary DNA base modifications identified to date. Here we show it is possible to use surface enhanced Raman spectroscopy (SERS) to detect these primary DNA base modifications. SERS detection of modified DNA bases is label-free and requires minimal additional sample preparation, reducing the possibility of additional chemical modifications induced prior to measurement. This approach shows the feasibility of DNA base modification assessment as a potentially routine analysis that may be further developed for clinical diagnostics.

  16. Biosensors based on surface plasmon-enhanced fluorescence spectroscopy.

    PubMed

    Dostálek, Jakub; Knoll, Wolfgang

    2008-09-01

    The implementation of surface plasmon-enhanced fluorescence spectroscopy (SPFS) to surface plasmon resonance (SPR) biosensors enables increasing their sensitivity by several orders of magnitude. In SPR-based biosensors, surface plasmons probe the binding of target molecules contained in a liquid sample by their affinity partners attached to a metallic sensor surface. SPR biosensors relying on the detection of refractive index changes allow for direct observation of the binding of large and medium size molecules that produces sufficiently large refractive index changes. In SPR biosensors exploiting SPFS, the capture of fluorophore-labeled molecules to the sensor surface is observed by the detection of fluorescence light emitted from the surface. This technique takes advantage of the enhanced intensity of electromagnetic field accompanied with the resonant excitation of surface plasmons. The interaction with surface plasmons can greatly increase the measured fluorescence signal through enhancing the excitation rate of fluorophores and by more efficient collecting of fluorescence light. SPFS-based biosensors were shown to enable the analysis of samples with extremely low analyte concentrations and the detection of small molecules. In this review, we describe the fundamental principles, implementations, and current state of the art applications of SPFS biosensors. This review focuses on SPFS-based biosensors employing the excitation of surface plasmons on continuous metal-dielectric interfaces.

  17. 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…

  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. 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

  2. RNA-seq based transcriptomic analysis of single bacterial cells.

    PubMed

    Wang, Jiangxin; Chen, Lei; Chen, Zixi; Zhang, Weiwen

    2015-11-01

    Gene-expression heterogeneity among individual cells determines the fate of a bacterial population. Here we report the first bacterial single-cell RNA sequencing (RNA-seq), BaSiC RNA-seq, a method integrating RNA isolation, cDNA synthesis and amplification, and RNA-seq analysis of the whole transcriptome of single cyanobacterium Synechocystis sp. PCC 6803 cells which typically contain approximately 5-7 femtogram total RNA per cell. We applied the method to 3 Synechocystis single cells at 24 h and 3 single cells at 72 h after nitrogen-starvation stress treatment, as well as their bulk-cell controls under the same conditions, to determine the heterogeneity upon environmental stress. With 82-98% and 31-48% of all putative Synechocystis genes identified in single cells of 24 and 72 h, respectively, the results demonstrated that the method could achieve good identification of the transcripts in single bacterial cells. In addition, the preliminary results from nitrogen-starved cells also showed a possible increasing gene-expression heterogeneity from 24 h to 72 h after nitrogen starvation stress. Moreover, preliminary analysis of single-cell transcriptomic datasets revealed that genes from the "Mobile elements" functional category have the most significant increase of gene-expression heterogeneity upon stress, which was further confirmed by single-cell RT-qPCR analysis of gene expression in 24 randomly selected cells.

  3. Dynamics of single and multiple asteroids based on Gaia observations

    NASA Astrophysics Data System (ADS)

    Hestroffer, D.

    2014-07-01

    Solar System. Gaia will also, indirectly, enhance our knowledge of the Solar System based on the use of the stellar catalogue itself. It will generally improve the astrometry of these bodies (from new CCD measurements or old photographic plate rereduction) or prediction and observation of stellar occultations, opening again the way to new developments in the studies of Solar System bodies. Beyond the mission itself, the scientific exploitation of the collected data and the use of complementary observations (larger time span, higher spatial resolution, time frequency, etc.) will also bring major contributions to the study of Small Bodies of the Solar System.

  4. Quantitative Single-Molecule Surface-Enhanced Raman Scattering by Optothermal Tuning of DNA Origami-Assembled Plasmonic Nanoantennas.

    PubMed

    Simoncelli, Sabrina; Roller, Eva-Maria; Urban, Patrick; Schreiber, Robert; Turberfield, Andrew J; Liedl, Tim; Lohmüller, Theobald

    2016-11-22

    DNA origami is a powerful approach for assembling plasmonic nanoparticle dimers and Raman dyes with high yields and excellent positioning control. Here we show how optothermal-induced shrinking of a DNA origami template can be employed to control the gap sizes between two 40 nm gold nanoparticles in a range from 1 to 2 nm. The high field confinement achieved with this optothermal approach was demonstrated by detection of surface-enhanced Raman spectroscopy (SERS) signals from single molecules that are precisely placed within the DNA origami template that spans the nanoparticle gap. By comparing the SERS intensity with respect to the field enhancement in the plasmonic hot-spot region, we found good agreement between measurement and theory. Our straightforward approach for the fabrication of addressable plasmonic nanosensors by DNA origami demonstrates a path toward future sensing applications with single-molecule resolution.

  5. Does solitary incubation enhance egg water uptake and offspring quality in a lizard that produces single-egg clutches?

    PubMed

    Warner, Daniel A; Chapman, Michelle N

    2011-03-01

    Many organisms invariably produce one offspring per reproductive bout, but experimental tests of adaptive explanations for this reproductive pattern are rare. To address this issue, we studied a lizard (Anolis sagrei) that produces one egg at a time to test the hypothesis that solitary incubation (due to single-egg clutches) eliminates competition with adjacent eggs for moisture and thus enhances offspring quality via increased egg water uptake during development. Our findings suggest that solitary incubation does not affect rates of moisture uptake by eggs or offspring size. However, egg moisture uptake and offspring size were negatively affected when eggs were adjacent to an egg that died during development. Depending on rates of infertile eggs or embryo mortality in the field, single-egg clutches may improve developmental environments and enhance offspring fitness. These results highlight the importance of considering the role of plastic embryonic responses during development in explaining reproductive patterns.

  6. Influence of picosecond multiple/single line ablation on copper nanoparticles fabricated for surface enhanced Raman spectroscopy and photonics applications

    NASA Astrophysics Data System (ADS)

    Hamad, Syed; Krishna Podagatlapalli, G.; Tewari, Surya P.; Venugopal Rao, S.

    2013-12-01

    A comprehensive study comprising fabrication of copper nanoparticles (NPs) using picosecond (ps) multiple/single line ablation in various solvents such as acetone, dichloromethane (DCM), acetonitrile (ACN) and chloroform followed by optical, nonlinear optical (NLO), and surface enhanced Raman spectroscopy (SERS) characterization was performed. The influence of surrounding liquid media and the writing conditions resulted in fabrication of Cu NPs in acetone, CuCl NPs in DCM, CuO NPs in ACN and CuCl2 NPs in chloroform. Prepared colloids were characterized through transmission electron microscopy, energy dispersive x-ray spectra, selected area electron diffraction and UV-visible absorption spectra. A detailed investigation of the surface enhanced Raman scattering (SERS) activity and the ps NLO properties of the colloids prepared through multiple/single line ablation techniques revealed that the best performance was achieved by Cu NPs for SERS applications and CuCl2 NPs for NLO applications.

  7. Cavity-induced backaction in Purcell-enhanced photon emission of a single ion in an ultraviolet fiber cavity

    NASA Astrophysics Data System (ADS)

    Ballance, T. G.; Meyer, H. M.; Kobel, P.; Ott, K.; Reichel, J.; Köhl, M.

    2017-03-01

    We study the behavior of a single laser-driven trapped ion inside a microscopic optical Fabry-Perot cavity. In particular, we demonstrate a fiber Fabry-Perot cavity operating on the principal S1 /2→P1 /2 electric dipole transition of an Yb+ ion at 369 nm with an ion-cavity coupling strength of g =2 π ×67 (1 ) MHz. We employ the cavity to study the generation of single photons and observe cavity-induced backaction in the Purcell-enhanced emission of photons. Tuning of the amplitude and phase between the driving field and the cavity field built up from photons scattered into the cavity mode by the ion allows us to enhance or suppress the total rate of photon emission from the ion-cavity system.

  8. Single MIMO-OTA and single-grounded-capacitor-based first-order allpass filter design

    NASA Astrophysics Data System (ADS)

    Psychalinos, C.; Pal, K.; Khanday, F. A.

    2014-12-01

    A novel first-order voltage-mode allpass (AP) filter employing a single multiple-input-multiple-output operational-transconductance-amplifier (MIMO-OTA) and a single grounded capacitor is introduced in this article. Compared to the corresponding already published topologies, the offered benefits are as follows: it employs minimum number of active and passive components; the only capacitor is grounded, which is good for a monolithic integration of an IC; and the absence of any matching condition for its realisability. The performance of the proposed circuit has been evaluated through simulation results, utilising the analogue design environment of Cadence software.

  9. Surface plasmon enhanced photodetectors based on internal photoemission

    NASA Astrophysics Data System (ADS)

    Alavirad, Mohammad; Roy, Langis; Berini, Pierre

    2016-10-01

    Surface plasmon photodetectors are of broad interest. They are promising for several applications including telecommunications, photovoltaic solar cells, photocatalysis, color-sensitive detection, and sensing, as they can provide highly enhanced fields and strong confinement (to subwavelength scales). Such photodetectors typically combine a nanometallic structure that supports surface plasmons with a photodetection structure based on internal photoemission or electron-hole pair creation. Photodetector architectures are highly varied, including waveguides, gratings, nanoparticles, nanoislands, or nanoantennas. We review the operating principles behind surface plasmon photodetectors based on the internal photoelectric effect, and we survey and compare the most recent and leading edge concepts reported in the literature.

  10. 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

  11. Dual-energy computed tomography for the assessment of early treatment effects of regorafenib in a preclinical tumor model: comparison with dynamic contrast-enhanced CT and conventional contrast-enhanced single-energy CT.

    PubMed

    Knobloch, Gesine; Jost, Gregor; Huppertz, Alexander; Hamm, Bernd; Pietsch, Hubertus

    2014-08-01

    The potential diagnostic value of dual-energy computed tomography (DE-CT) compared to dynamic contrast-enhanced CT (DCE-CT) and conventional contrast-enhanced CT (CE-CT) in the assessment of early regorafenib treatment effects was evaluated in a preclinical setting. A rat GS9L glioma model was examined with contrast-enhanced dynamic DE-CT measurements (80 kV/140 kV) for 4 min before and on days 1 and 4 after the start of daily regorafenib or placebo treatment. Tumour time-density curves (0-240 s, 80 kV), DE-CT (60 s) derived iodine maps and the DCE-CT (0-30 s, 80 kV) based parameters blood flow (BF), blood volume (BV) and permeability (PMB) were calculated and compared to conventional CE-CT (60 s, 80 kV). The regorafenib group showed a marked decrease in the tumour time-density curve, a significantly lower iodine concentration and a significantly lower PMB on day 1 and 4 compared to baseline, which was not observed for the placebo group. CE-CT showed a significant decrease in tumour density on day 4 but not on day 1. The DE-CT-derived iodine concentrations correlated with PMB and BV but not with BF. DE-CT allows early treatment monitoring, which correlates with DCE-CT. Superior performance was observed compared to single-energy CE-CT. • Regorafenib treatment response was evaluated by CT in a rat tumour model. • Dual-energy contrast-enhanced CT allows early treatment monitoring of targeted anti-tumour therapies. • Dual-energy CT showed higher diagnostic potential than conventional contrast enhanced single-energy CT. • Dual-energy CT showed diagnostic potential comparable to dynamic contrast-enhanced CT. • Dual-energy CT is a promising method for efficient clinical treatment response evaluation.

  12. 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.

  13. Quenching and enhancement of single-molecule fluorescence under metallic and dielectric tips

    NASA Astrophysics Data System (ADS)

    Azoulay, J.; Débarre, A.; Richard, A.; Tchénio, P.

    2000-08-01

    We report on fluorescence experiments by apertureless near-field optical microscopy. We develop a simple model that demonstrates the importance of non-radiative transfer and that takes into account the dependence of non-radiative transfer on tip geometry. This process is in competition with field enhancement and it is a key process to understand the observed fluorescence enhancement factors. The analysis of the different factors involved in the global fluorescence enhancement or quenching leads to new strategies to reach resolution down to a few nanometers by apertureless fluorescence microscopy.

  14. Plasmonic enhancement of a whispering-gallery-mode biosensor for single nanoparticle detection

    NASA Astrophysics Data System (ADS)

    Shopova, S. I.; Rajmangal, R.; Holler, S.; Arnold, S.

    2011-06-01

    We describe and demonstrate a physical mechanism that substantially enhances the label-free sensitivity of a whispering-gallery-mode biosensor for the detection of individual nanoparticles in aqueous solution. It involves the interaction of dielectric nanoparticle in an equatorial carousel orbit with a plasmonic nanoparticle bound at the microparticle's equator. As the dielectric particle parks to hot spots on the plasmonic particle we observe frequency shifts that are enhanced by a factor of 4, consistent with a simple reactive model. Once optimized the enhancement by this mechanism should exceed several orders of magnitude, putting individual protein within reach.

  15. Recent Enhancements to the Development of CFD-Based Aeroelastic Reduced-Order Models

    NASA Technical Reports Server (NTRS)

    Silva, Walter A.

    2007-01-01

    Recent enhancements to the development of CFD-based unsteady aerodynamic and aeroelastic reduced-order models (ROMs) are presented. These enhancements include the simultaneous application of structural modes as CFD input, static aeroelastic analysis using a ROM, and matched-point solutions using a ROM. The simultaneous application of structural modes as CFD input enables the computation of the unsteady aerodynamic state-space matrices with a single CFD execution, independent of the number of structural modes. The responses obtained from a simultaneous excitation of the CFD-based unsteady aerodynamic system are processed using system identification techniques in order to generate an unsteady aerodynamic state-space ROM. Once the unsteady aerodynamic state-space ROM is generated, a method for computing the static aeroelastic response using this unsteady aerodynamic ROM and a state-space model of the structure, is presented. Finally, a method is presented that enables the computation of matchedpoint solutions using a single ROM that is applicable over a range of dynamic pressures and velocities for a given Mach number. These enhancements represent a significant advancement of unsteady aerodynamic and aeroelastic ROM technology.

  16. Sensitivity enhancement of grating interferometer based two-dimensional sensor arrays using two-wavelength readout.

    PubMed

    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-λ) 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 (~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. ~30% increase in the average sensitivity was demonstrated for a 160×120 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.

  17. 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.

  18. Chemiluminescence detector based on a single planar transparent digital microfluidic device.

    PubMed

    Zeng, Xiangyu; Zhang, Kaidi; Pan, Jian; Chen, Guoping; Liu, Ai-Qun; Fan, Shih-Kang; Zhou, Jia

    2013-07-21

    We report on a compact and portable prototype of chemiluminescence detector based on a single planar single polar transparent electrowetting-on-dielectrics (EWOD) device. The coupling ground model was proposed to build the EWOD device, which could be driven under a single polar voltage. Such a design not only simplified the chip construction and control circuit, but also had the potential for the ball-like droplet to focus the fluorescence and enhance the detection sensitivity. Simulations and experiments both confirmed that the greater the contact angle, the stronger the detected optical signal, and thus the higher the sensitivity. The sensitivity of the prototype detector to H2O2 was 5.45 mV (mmol L(-1))(-1) and the detection limit was 0.01 mmol L(-1) when the contact angle of the EWOD surface was 120°. To further increase the sensitivity and decrease the detection limit, the contact angle of the EWOD device could be increased and the dark current of the photomultiplier decreased. The prototype shows potential applications as highly sensitive, cost effective and portable immuno-detectors, especially as a blood glucose monitor.

  19. 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.

  20. 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.

  1. Enhanced smartcard-based password-authenticated key agreement using extended chaotic maps.

    PubMed

    Lee, Tian-Fu; Hsiao, Chia-Hung; Hwang, Shi-Han; Lin, Tsung-Hung

    2017-01-01

    A smartcard based password-authenticated key agreement scheme enables a legal user to log in to a remote authentication server and access remote services through public networks using a weak password and a smart card. Lin recently presented an improved chaotic maps-based password-authenticated key agreement scheme that used smartcards to eliminate the weaknesses of the scheme of Guo and Chang, which does not provide strong user anonymity and violates session key security. However, the improved scheme of Lin does not exhibit the freshness property and the validity of messages so it still fails to withstand denial-of-service and privileged-insider attacks. Additionally, a single malicious participant can predetermine the session key such that the improved scheme does not exhibit the contributory property of key agreements. This investigation discusses these weaknesses and proposes an enhanced smartcard-based password-authenticated key agreement scheme that utilizes extended chaotic maps. The session security of this enhanced scheme is based on the extended chaotic map-based Diffie-Hellman problem, and is proven in the real-or-random and the sequence of games models. Moreover, the enhanced scheme ensures the freshness of communicating messages by appending timestamps, and thereby avoids the weaknesses in previous schemes.

  2. Enhanced smartcard-based password-authenticated key agreement using extended chaotic maps

    PubMed Central

    Lee, Tian-Fu; Hsiao, Chia-Hung; Hwang, Shi-Han

    2017-01-01

    A smartcard based password-authenticated key agreement scheme enables a legal user to log in to a remote authentication server and access remote services through public networks using a weak password and a smart card. Lin recently presented an improved chaotic maps-based password-authenticated key agreement scheme that used smartcards to eliminate the weaknesses of the scheme of Guo and Chang, which does not provide strong user anonymity and violates session key security. However, the improved scheme of Lin does not exhibit the freshness property and the validity of messages so it still fails to withstand denial-of-service and privileged-insider attacks. Additionally, a single malicious participant can predetermine the session key such that the improved scheme does not exhibit the contributory property of key agreements. This investigation discusses these weaknesses and proposes an enhanced smartcard-based password-authenticated key agreement scheme that utilizes extended chaotic maps. The session security of this enhanced scheme is based on the extended chaotic map-based Diffie-Hellman problem, and is proven in the real-or-random and the sequence of games models. Moreover, the enhanced scheme ensures the freshness of communicating messages by appending timestamps, and thereby avoids the weaknesses in previous schemes. PMID:28759615

  3. 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.

  4. Toward Low-Voltage and Bendable X-Ray Direct Detectors Based on Organic Semiconducting Single Crystals.

    PubMed

    Ciavatti, Andrea; Capria, Ennio; Fraleoni-Morgera, Alessandro; Tromba, Giuliana; Dreossi, Diego; Sellin, Paul J; Cosseddu, Piero; Bonfiglio, Annalisa; Fraboni, Beatrice

    2015-11-25

    Organic materials have been mainly proposed as ionizing radiation detectors in the indirect conversion approach. The first thin and bendable X-ray direct detectors are realized (directly converting X-photons into an electric signal) based on organic semiconducting single crystals that possess enhanced sensitivity, low operating voltage (≈5 V), and a minimum detectable dose rate of 50 μGy s(-1) .

  5. Dielectrophoretic positioning of single nanoparticles on atomic force microscope tips for tip-enhanced Raman spectroscopy.

    PubMed

    Leiterer, Christian; Deckert-Gaudig, Tanja; Singh, Prabha; Wirth, Janina; Deckert, Volker; Fritzsche, Wolfgang

    2015-05-01

    Tip-enhanced Raman spectroscopy, a combination of Raman spectroscopy and scanning probe microscopy, is a powerful technique to detect the vibrational fingerprint of molecules at the nanometer scale. A metal nanoparticle at the apex of an atomic force microscope tip leads to a large enhancement of the electromagnetic field when illuminated with an appropriate wavelength, resulting in an increased Raman signal. A controlled positioning of individual nanoparticles at the tip would improve the reproducibility of the probes and is quite demanding due to usually serial and labor-intensive approaches. In contrast to commonly used submicron manipulation techniques, dielectrophoresis allows a parallel and scalable production, and provides a novel approach toward reproducible and at the same time affordable tip-enhanced Raman spectroscopy tips. We demonstrate the successful positioning of an individual plasmonic nanoparticle on a commercial atomic force microscope tip by dielectrophoresis followed by experimental proof of the Raman signal enhancing capabilities of such tips.

  6. A physically based constitutive model for FCC single crystals with a single state variable per slip system

    NASA Astrophysics Data System (ADS)

    Demir, Eralp

    2017-01-01

    A new, simple and physically consistent dislocation-density-based continuum model is developed in a large-strain crystal plasticity framework. All the constitutive laws are expressed in a simple and unique way in terms of a single state variable dislocation density. The proposed physically based model predicts experimental single-crystal stress-strain curves along different crystal directions more accurately than a classical model with widely accepted constitutive laws. The polycrystal texture predictions from the dislocation-density-based and classical models having the same single-crystal stress-strain characteristics are in good agreement with the classical model when Taylor-type homogenization is used in conjunction with enough number of grains.

  7. Enhanced solar energy conversion in Au-doped, single-wall carbon nanotube-Si heterojunction cells

    PubMed Central

    2013-01-01

    The power conversion efficiency (PCE) of single-wall carbon nanotube (SCNT)/n-type crystalline silicon heterojunction photovoltaic devices is significantly improved by Au doping. It is found that the overall PCE was significantly increased to threefold. The efficiency enhancement of photovoltaic devices is mainly the improved electrical conductivity of SCNT by increasing the carrier concentration and the enhancing the absorbance of active layers by Au nanoparticles. The Au doping can lead to an increase of the open circuit voltage through adjusting the Fermi level of SCNT and then enhancing the built-in potential in the SCNT/n-Si junction. This fabrication is easy, cost-effective, and easily scaled up, which demonstrates that such Au-doped SCNT/Si cells possess promising potential in energy harvesting application. PMID:23663755

  8. Sensitivity enhancement in static solid-state NMR experiments via single- and multiple-quantum dipolar coherences.

    PubMed

    Gopinath, T; Veglia, Gianluigi

    2009-04-29

    We present a new method for enhancing the sensitivity in static solid-state NMR experiments for a gain in signal-to-noise ratio of up to 40%. This sensitivity enhancement is different from the corresponding solution NMR sensitivity enhancement schemes and is achieved by combining single- and multiple-quantum dipolar coherences. While this new approach is demonstrated for the polarization inversion spin exchange at magic angle (PISEMA) experiment, it can be generalized to the other separated local field experiments for solid-state NMR spectroscopy. This method will have a direct impact on solid-state NMR spectroscopy of liquid crystals as well as of membrane proteins aligned in lipid membranes.

  9. Enhancing ammonium oxidizing bacteria activity was key to single-stage partial nitrification-anammox system treating low-strength sewage under intermittent aeration condition.

    PubMed

    Miao, Yuanyuan; Zhang, Liang; Li, Baikun; Zhang, Qian; Wang, Simeng; Peng, Yongzhen

    2017-05-01

    Intermittent aeration and bio-augmentation were integrated to enhance single-stage partial nitrification-anammox (SPN/A) stability over 235-day operational period treating low-strength sewage. The effect of bio-augmentation sludge (with different abundances of ammonium oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB)) was determined. Partial nitrification sludge based bio-augmentation increased the total nitrogen (TN) removal efficiency from 29.1% to 70%, followed by the nitrification sludge (from 38.1% to 65.4%), then the denitrifying phosphorus sludge (from 42.1% to 54.4%). The evolution of bacteria activity and communities showed that anammox activity increased with the enhancement of AOB activity, and higher AOB abundance led to higher anammox bacterial abundance despite high NOB abundance. The enhancement of AOB activity produced more nitrite, anammox bacteria gained more nitrite than NOB since intermittent aeration selectively inhibited NOB, thus the reactor stability enhanced substantially. This study highlights the significance of enhancing AOB activity to ensure long-term operational stability of SPN/A processes. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Atom devices based on single dopants in silicon nanostructures

    PubMed Central

    2011-01-01

    Silicon field-effect transistors have now reached gate lengths of only a few tens of nanometers, containing a countable number of dopants in the channel. Such technological trend brought us to a research stage on devices working with one or a few dopant atoms. In this work, we review our most recent studies on key atom devices with fundamental structures of silicon-on-insulator MOSFETs, such as single-dopant transistors, preliminary memory devices, single-electron turnstile devices and photonic devices, in which electron tunneling mediated by single dopant atoms is the essential transport mechanism. Furthermore, observation of individual dopant potential in the channel by Kelvin probe force microscopy is also presented. These results may pave the way for the development of a new device technology, i.e., single-dopant atom electronics. PMID:21801408

  11. Deep neural network and noise classification-based speech enhancement

    NASA Astrophysics Data System (ADS)

    Shi, Wenhua; Zhang, Xiongwei; Zou, Xia; Han, Wei

    2017-07-01

    In this paper, a speech enhancement method using noise classification and Deep Neural Network (DNN) was proposed. Gaussian mixture model (GMM) was employed to determine the noise type in speech-absent frames. DNN was used to model the relationship between noisy observation and clean speech. Once the noise type was determined, the corresponding DNN model was applied to enhance the noisy speech. GMM was trained with mel-frequency cepstrum coefficients (MFCC) and the parameters were estimated with an iterative expectation-maximization (EM) algorithm. Noise type was updated by spectrum entropy-based voice activity detection (VAD). Experimental results demonstrate that the proposed method could achieve better objective speech quality and smaller distortion under stationary and non-stationary conditions.

  12. Portable fiber sensors based on surface-enhanced Raman scattering.

    PubMed

    Yang, Xuan; Tanaka, Zuki; Newhouse, Rebecca; Xu, Qiao; Chen, Bin; Chen, Shaowei; Zhang, Jin Z; Gu, Claire

    2010-12-01

    Two portable molecular sensing systems based on surface-enhanced Raman scattering (SERS) have been experimentally demonstrated using either a tip-coated multimode fiber (TCMMF) or a liquid core photonic crystal fiber (LCPCF) as the SERS probe. With Rhodamine 6G as a test molecule, the TCMMF-portable SERS system achieved 2-3 times better sensitivity than direct sampling (focusing the laser light directly into the sample without the fiber probe), and a highly sensitive LCPCF-portable SERS system reached a sensitivity up to 59 times that of direct sampling, comparable to the sensitivity enhancement achieved using fiber probes in the bulky Renishaw system. These fiber SERS probes integrated with a portable Raman spectrometer provide a promising scheme for a compact and flexible molecular sensing system with high sensitivity and portability.

  13. 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.

  14. Single-cell printing based on impedance detection

    PubMed Central

    Schoendube, J.; Wright, D.; Zengerle, R.; Koltay, P.

    2015-01-01

    Label-free isolation of single cells is essential for the growing field of single-cell analysis. Here, we present a device which prints single living cells encapsulated in free-flying picoliter droplets. It combines inkjet printing and impedance flow cytometry. Droplet volume can be controlled in the range of 500 pl–800 pl by piezo actuator displacement. Two sets of parallel facing electrodes in a 50 μm × 55 μm channel are applied to measure the presence and velocity of a single cell in real-time. Polystyrene beads with <5% variation in diameter generated signal variations of 12%–17% coefficients of variation. Single bead efficiency (i.e., printing events with single beads vs. total number of printing events) was 73% ± 11% at a throughput of approximately 9 events/min. Viability of printed HeLa cells and human primary fibroblasts was demonstrated by culturing cells for at least eight days. PMID:25759750

  15. Single-cell printing based on impedance detection.

    PubMed

    Schoendube, J; Wright, D; Zengerle, R; Koltay, P

    2015-01-01

    Label-free isolation of single cells is essential for the growing field of single-cell analysis. Here, we present a device which prints single living cells encapsulated in free-flying picoliter droplets. It combines inkjet printing and impedance flow cytometry. Droplet volume can be controlled in the range of 500 pl-800 pl by piezo actuator displacement. Two sets of parallel facing electrodes in a 50 μm × 55 μm channel are applied to measure the presence and velocity of a single cell in real-time. Polystyrene beads with <5% variation in diameter generated signal variations of 12%-17% coefficients of variation. Single bead efficiency (i.e., printing events with single beads vs. total number of printing events) was 73% ± 11% at a throughput of approximately 9 events/min. Viability of printed HeLa cells and human primary fibroblasts was demonstrated by culturing cells for at least eight days.

  16. Development of Single-Molecule DNA Sequencing Platform Based on Single-Molecule Electrical Conductance

    DTIC Science & Technology

    2015-05-25

    suggests that gold nanoparticles (GNPs) activate B-cells and enhance immunoglobulin G secretion. GNP treatment upregulates blimp1, downregulates pax5...SUPPLEMENTARY NOTES 14. ABSTRACT The significant findings in this report come from the in vitro, ex vivo, and in vivo evidence data which suggests that gold ...nano interface on the immune system. The key component of the protein transistor is the binding interface of gold nanoparticles (GNPs) and antibody

  17. High-Throughput Single-Particle Analysis of Metal-Enhanced Fluorescence in Free Solution Using Ag@SiO2 Core-Shell Nanoparticles.

    PubMed

    Yan, Ya; Meng, Lingyan; Zhang, Wenqiang; Zheng, Yan; Wang, Shuo; Ren, Bin; Yang, Zhilin; Yan, Xiaomei

    2017-09-22

    Metal-enhanced fluorescence (MEF) based on localized surface plasmon resonance (LSPR) is an effective strategy to increase the detection sensitivity in biotechnology and biomedicine. Because plasmonic nanoparticles are intrinsically heterogeneous, high-throughput single-particle analysis of MEF in free solution are highly demanded for the mechanistic understanding and control of this nanoscale process. Here, we report the application of a laboratory-built high-sensitivity flow cytometer (HSFCM) to investigate the fluorescence-enhancing effect of individual plasmonic nanoparticles on nearby fluorophore molecules. Ag@SiO2 core-shell nanoparticles were used as the model system which comprised a silver core, a silica shell, and an FITC-doped thin layer of silica shell. FITC-doped silica nanoparticles of the same particle size but without silver core were used as the counterparts. Both the side scattering and fluorescence signals of single nanoparticles in suspension were measured simultaneously by the HSFCM at a speed of thousands of particles per minute. The roles of silver core size (40-100 nm) and fluorophore-metal distance (5-30 nm) were systematically examined. Fluorescence enhancement factor exceeding 30 was observed at silver core size of 70 nm and silica shell thickness of 5 nm. Compared with ensemble-averaged spectrofluorometric measurements, our experimental observation at the single-particle level was well supported by the finite difference time domain (FDTD) calculation. It allows us to achieve a fundamental understanding of MEF, which is important to the design and control of plasmonic nanostructures for efficient fluorescence enhancement.

  18. Discriminating single-molecule sensing by crown-ether-based molecular junctions

    NASA Astrophysics Data System (ADS)

    Ismael, Ali K.; Al-Jobory, Alaa; Grace, Iain; Lambert, Colin J.

    2017-02-01

    Crown-ether molecules are well known to selectively bind alkali atoms, so by incorporating these within wires, any change in electrical conductance of the wire upon binding leads to discriminating sensing. Using a density functional theory-based approach to quantum transport, we investigate the potential sensing capabilities of single-molecule junctions formed from crown ethers attached to anthraquinone units, which are in turn attached to gold electrodes via alkyl chains. We calculate the change in electrical conductance for binding of three different alkali ions (lithium, sodium, and potassium). Depending on the nature of the ionic analyte, the conductance is enhanced by different amounts. This change in electrical conductance is due to charge transfer from the ion to molecular wire causing the molecular resonances to shift closer to the electrode Fermi energy.

  19. Orientation dependence of electromechanical properties of relaxor based ferroelectric single crystals.

    PubMed

    Xiang, Yang; Zhang, Rui; Cao, Wenwu

    2011-01-01

    The orientation dependence of electromechanical properties of relaxor based ferroelectric single crystals Pb(Zn1/3Nb2/3)O3-(6-7)%PbTiO3 and Pb(Mg1/3Nb2/3)O3-33%PbTiO3 has been calculated by coordinate transformation. Different from previous studies, the optimum cutting orientations have been predicted in terms of their piezoelectric responses in the corresponding crystal planes. The calculation results indicated that the anisotropic piezoelectric effects of [001] c and [011] c poled multi-domain crystals mainly come from the intrinsic contribution. However, the strong dielectric anisotropy of [001] c poled multi-domain crystals mainly comes from extrinsic domain and domain wall contributions. For [011] c poled multi-domain crystals, the intrinsic orientation effect enhances the dielectric anisotropy.

  20. Enhanced thermoelectric performance of SnSe based composites with carbon black nanoinclusions

    NASA Astrophysics Data System (ADS)

    Li, J. C.; Li, D.; Xu, W.; Qin, X. Y.; Li, Y. Y.; Zhang, J.

    2016-10-01

    Recently, a single crystalline SnSe and its sodium doped compound are reported to have an ultralow thermal conductivity and a high thermoelectric figure of merit. However, the highest thermoelectric figure of merit for polycrystalline SnSe-based materials is not larger than 1. In this study, we report a high thermoelectric figure of merit 1.21 at 903 K for poly-crystalline SnSe, realized by incorporating a proper proportion of carbon black as nano-inclusions. The exceptional performance arises from the enhanced power factor, coming from an increased electrical conductivity at high temperatures.