WorldWideScience

Sample records for surface sensitive analytical

  1. Encyclopedia of analytical surfaces

    CERN Document Server

    Krivoshapko, S N

    2015-01-01

    This encyclopedia presents an all-embracing collection of analytical surface classes. It provides concise definitions  and description for more than 500 surfaces and categorizes them in 38 classes of analytical surfaces. All classes are cross references to the original literature in an excellent bibliography. The encyclopedia is of particular interest to structural and civil engineers and serves as valuable reference for mathematicians.

  2. Sample handling in surface sensitive chemical and biological sensing: a practical review of basic fluidics and analyte transport.

    Science.gov (United States)

    Orgovan, Norbert; Patko, Daniel; Hos, Csaba; Kurunczi, Sándor; Szabó, Bálint; Ramsden, Jeremy J; Horvath, Robert

    2014-09-01

    This paper gives an overview of the advantages and associated caveats of the most common sample handling methods in surface-sensitive chemical and biological sensing. We summarize the basic theoretical and practical considerations one faces when designing and assembling the fluidic part of the sensor devices. The influence of analyte size, the use of closed and flow-through cuvettes, the importance of flow rate, tubing length and diameter, bubble traps, pressure-driven pumping, cuvette dead volumes, and sample injection systems are all discussed. Typical application areas of particular arrangements are also highlighted, such as the monitoring of cellular adhesion, biomolecule adsorption-desorption and ligand-receptor affinity binding. Our work is a practical review in the sense that for every sample handling arrangement considered we present our own experimental data and critically review our experience with the given arrangement. In the experimental part we focus on sample handling in optical waveguide lightmode spectroscopy (OWLS) measurements, but the present study is equally applicable for other biosensing technologies in which an analyte in solution is captured at a surface and its presence is monitored. Explicit attention is given to features that are expected to play an increasingly decisive role in determining the reliability of (bio)chemical sensing measurements, such as analyte transport to the sensor surface; the distorting influence of dead volumes in the fluidic system; and the appropriate sample handling of cell suspensions (e.g. their quasi-simultaneous deposition). At the appropriate places, biological aspects closely related to fluidics (e.g. cellular mechanotransduction, competitive adsorption, blood flow in veins) are also discussed, particularly with regard to their models used in biosensing.

  3. Analytic vortex solutions on compact hyperbolic surfaces

    CERN Document Server

    Maldonado, R

    2015-01-01

    We construct, for the first time, Abelian-Higgs vortices on certain compact surfaces of constant negative curvature. Such surfaces are represented by a tessellation of the hyperbolic plane by regular polygons. The Higgs field is given implicitly in terms of Schwarz triangle functions and analytic solutions are available for certain highly symmetric configurations.

  4. Analytic vortex solutions on compact hyperbolic surfaces

    Science.gov (United States)

    Maldonado, Rafael; Manton, Nicholas S.

    2015-06-01

    We construct, for the first time, abelian Higgs vortices on certain compact surfaces of constant negative curvature. Such surfaces are represented by a tessellation of the hyperbolic plane by regular polygons. The Higgs field is given implicitly in terms of Schwarz triangle functions and analytic solutions are available for certain highly symmetric configurations.

  5. Conducting polymer nanofibers for high sensitivity detection of chemical analytes.

    Science.gov (United States)

    Kumar, Abhishek; Leshchiner, Ignaty; Nagarajan, Subhalakshmi; Nagarajan, Ramaswamy; Kumar, Jayant

    2008-03-01

    Possessing large surface area materials is vital for high sensitivity detection of analyte. We report a novel, inexpensive and simple technique to make high surface area sensing interfaces using electrospinning. Conducting polymers (CP) nanotubes were made by electrospinning a solution of a catalyst (ferric tosylate) along with poly (lactic acid), which is an environment friendly biodegradable polymer. Further vapor deposition polymerization of the monomer ethylenedioxy thiophene (EDOT) on the nanofiber surface yielded poly (EDOT) covered fibers. X-ray photo electron spectroscopy (XPS) study reveals the presence of PEDOT predominantly on the surface of nanofibers. Conducting nanotubes had been received by dissolving the polymer in the fiber core. By a similar technique we had covalently incorporated fluorescent dyes on the nanofiber surface. The materials obtained show promise as efficient sensing elements. UV-Vis characterization confirms the formation of PEDOT nanotubes and incorporation of chromophores on the fiber surface. The morphological characterization was carried out using scanning electron microscopy (SEM) and transmission electron microscopy (TEM).

  6. Surface Sensitive Microfluidic Optomechanical Sensors

    CERN Document Server

    Kim, Kyu Hyun

    2014-01-01

    The microfluidic optomechanical resonator (uFOMR) based on a thin-walled glass capillary supports high Q-factor (>1000) mechanical modes in the presence of liquids. In this Letter, the sensitivity of the uFOMR to the surface change is studied by layer-by-layer removal of SiO2 molecules from the uFOMR inner surface using various concentrations of hydrofluoric acid solutions. A frequency downshift is observed with a sensitivity of 1.2 Hz/(pg/mm2), which translates to a surface density detection limit of 83 pg/mm2. This work opens a door to using the optomechanical mode for detection and characterization of molecules present near the resonator surface.

  7. On accuracy problems for semi-analytical sensitivity analyses

    DEFF Research Database (Denmark)

    Pedersen, P.; Cheng, G.; Rasmussen, John

    1989-01-01

    The semi-analytical method of sensitivity analysis combines ease of implementation with computational efficiency. A major drawback to this method, however, is that severe accuracy problems have recently been reported. A complete error analysis for a beam problem with changing length is carried ou...... pseudo loads in order to obtain general load equilibrium with rigid body motions. Such a method would be readily applicable for any element type, whether analytical expressions for the element stiffnesses are available or not. This topic is postponed for a future study....

  8. An analytic method for sensitivity analysis of complex systems

    Science.gov (United States)

    Zhu, Yueying; Wang, Qiuping Alexandre; Li, Wei; Cai, Xu

    2017-03-01

    Sensitivity analysis is concerned with understanding how the model output depends on uncertainties (variances) in inputs and identifying which inputs are important in contributing to the prediction imprecision. Uncertainty determination in output is the most crucial step in sensitivity analysis. In the present paper, an analytic expression, which can exactly evaluate the uncertainty in output as a function of the output's derivatives and inputs' central moments, is firstly deduced for general multivariate models with given relationship between output and inputs in terms of Taylor series expansion. A γ-order relative uncertainty for output, denoted by Rvγ, is introduced to quantify the contributions of input uncertainty of different orders. On this basis, it is shown that the widely used approximation considering the first order contribution from the variance of input variable can satisfactorily express the output uncertainty only when the input variance is very small or the input-output function is almost linear. Two applications of the analytic formula are performed to the power grid and economic systems where the sensitivities of both actual power output and Economic Order Quantity models are analyzed. The importance of each input variable in response to the model output is quantified by the analytic formula.

  9. A new and consistent parameter for measuring the quality of multivariate analytical methods: Generalized analytical sensitivity.

    Science.gov (United States)

    Fragoso, Wallace; Allegrini, Franco; Olivieri, Alejandro C

    2016-08-24

    Generalized analytical sensitivity (γ) is proposed as a new figure of merit, which can be estimated from a multivariate calibration data set. It can be confidently applied to compare different calibration methodologies, and helps to solve literature inconsistencies on the relationship between classical sensitivity and prediction error. In contrast to the classical plain sensitivity, γ incorporates the noise properties in its definition, and its inverse is well correlated with root mean square errors of prediction in the presence of general noise structures. The proposal is supported by studying simulated and experimental first-order multivariate calibration systems with various models, namely multiple linear regression, principal component regression (PCR) and maximum likelihood PCR (MLPCR). The simulations included instrumental noise of different types: independently and identically distributed (iid), correlated (pink) and proportional noise, while the experimental data carried noise which is clearly non-iid.

  10. An analytic method for sensitivity analysis of complex systems

    CERN Document Server

    Zhu, Yueying; Li, Wei; Cai, Xu

    2016-01-01

    Sensitivity analysis is concerned with understanding how the model output depends on uncertainties (variances) in inputs and then identifies which inputs are important in contributing to the prediction imprecision. Uncertainty determination in output is the most crucial step in sensitivity analysis. In the present paper, an analytic expression, which can exactly evaluate the uncertainty in output as a function of the output's derivatives and inputs' central moments, is firstly deduced for general multivariate models with given relationship between output and inputs in terms of Taylor series expansion. A $\\gamma$-order relative uncertainty for output, denoted by $\\mathrm{R^{\\gamma}_v}$, is introduced to quantify the contributions of input uncertainty of different orders. On this basis, it is shown that the widely used approximation considering the first order contribution from the variance of input variable can satisfactorily express the output uncertainty only when the input variance is very small or the inpu...

  11. Surface enhanced raman spectroscopy analytical, biophysical and life science applications

    CERN Document Server

    Schlücker, Sebastian

    2013-01-01

    Covering everything from the basic theoretical and practical knowledge to new exciting developments in the field with a focus on analytical and life science applications, this monograph shows how to apply surface-enhanced Raman scattering (SERS) for solving real world problems. From the contents: * Theory and practice of SERS * Analytical applications * SERS combined with other analytical techniques * Biophysical applications * Life science applications including various microscopies Aimed at analytical, surface and medicinal chemists, spectroscopists, biophysicists and materials scientists. Includes a Foreword by the renowned Raman spectroscopist Professor Wolfgang Kiefer, the former Editor-in-Chief of the Journal of Raman Spectroscopy.

  12. Adequacy of surface analytical tools for studying the tribology of ceramics

    Science.gov (United States)

    Sliney, H. E.

    1986-01-01

    Surface analytical tools are very beneficial in tribological studies of ceramics. Traditional methods of optical microscopy, XRD, XRF, and SEM should be combined with newer surface sensitive techniques especially AES and XPS. ISS and SIMS can also be useful in providing additional compositon details. Tunneling microscopy and electron energy loss spectroscopy are less known techniques that may also prove useful.

  13. Applications of surface analytical techniques in Earth Sciences

    Science.gov (United States)

    Qian, Gujie; Li, Yubiao; Gerson, Andrea R.

    2015-03-01

    This review covers a wide range of surface analytical techniques: X-ray photoelectron spectroscopy (XPS), scanning photoelectron microscopy (SPEM), photoemission electron microscopy (PEEM), dynamic and static secondary ion mass spectroscopy (SIMS), electron backscatter diffraction (EBSD), atomic force microscopy (AFM). Others that are relatively less widely used but are also important to the Earth Sciences are also included: Auger electron spectroscopy (AES), low energy electron diffraction (LEED) and scanning tunnelling microscopy (STM). All these techniques probe only the very top sample surface layers (sub-nm to several tens of nm). In addition, we also present several other techniques i.e. Raman microspectroscopy, reflection infrared (IR) microspectroscopy and quantitative evaluation of minerals by scanning electron microscopy (QEMSCAN) that penetrate deeper into the sample, up to several μm, as all of them are fundamental analytical tools for the Earth Sciences. Grazing incidence synchrotron techniques, sensitive to surface measurements, are also briefly introduced at the end of this review. (Scanning) transmission electron microscopy (TEM/STEM) is a special case that can be applied to characterisation of mineralogical and geological sample surfaces. Since TEM/STEM is such an important technique for Earth Scientists, we have also included it to draw attention to the capability of TEM/STEM applied as a surface-equivalent tool. While this review presents most of the important techniques for the Earth Sciences, it is not an all-inclusive bibliography of those analytical techniques. Instead, for each technique that is discussed, we first give a very brief introduction about its principle and background, followed by a short section on approaches to sample preparation that are important for researchers to appreciate prior to the actual sample analysis. We then use examples from publications (and also some of our known unpublished results) within the Earth Sciences

  14. Ball assisted device for analytical surface sampling

    Science.gov (United States)

    ElNaggar, Mariam S; Van Berkel, Gary J; Covey, Thomas R

    2015-11-03

    A system for sampling a surface includes a sampling probe having a housing and a socket, and a rolling sampling sphere within the socket. The housing has a sampling fluid supply conduit and a sampling fluid exhaust conduit. The sampling fluid supply conduit supplies sampling fluid to the sampling sphere. The sampling fluid exhaust conduit has an inlet opening for receiving sampling fluid carried from the surface by the sampling sphere. A surface sampling probe and a method for sampling a surface are also disclosed.

  15. On stratification, barotropic tides, and secular changes in surface tidal elevations: Two-layer analytical models

    CERN Document Server

    Wetzel, Alfredo N; Cerovecki, Ivana; Hendershott, Myrl C; Karsten, Richard H; Miller, Peter D

    2013-01-01

    In this study the influence of stratification on surface tidal elevations in a two-layer analytical model is examined. The model assumes linearized, non-rotating, shallow-water dynamics in one dimension with astronomical forcing and allows for arbitrary topography. Both large scale (barotropic) and small scale (baroclinic) components of the surface tidal elevation are shown to be affected by stratification. It is also shown that the topography and basin boundaries affect the sensitivity of the barotropic surface tide to stratification significantly. In a companion paper it is shown that the barotropic tide in two-layer numerical models run in realistic global domains differs from its value in one-layer numerical models by amounts qualitatively consistent with analytic predictions from this paper. The analytical model also roughly predicts the sensitivity to perturbations in stratification in the two-layer domain model. Taken together, this paper and the companion paper therefore provide a framework to underst...

  16. Mass-Sensitive Biosensor Systems to Determine the Membrane Interaction of Analytes.

    Science.gov (United States)

    Hoß, Sebastian G; Bendas, Gerd

    2017-01-01

    Biosensors are devices that transform a biological interaction into a readout signal, which is evaluable for analytical purposes. The general strength of biosensor approaches is the avoidance of time-consuming and cost-intensive labeling procedures of the analytes. In this chapter, we give insight into a mass-sensitive surface-acoustic wave (SAW) biosensor, which represents an elegant and highly sensitive method to investigate binding events at a molecular level. The principle of SAW technology is based on the piezoelectric properties of the sensors, so as to binding events and their accompanied mass increase at the sensor surface are detectable by a change in the oscillation of the surface acoustic wave. In combination with model membranes, transferred to the sensor surface, the analytical value of SAW biosensors has strongly been increased and extended to different topics of biomedical investigations, including antibiotic research. The interaction with the bacterial membrane or certain target structures therein is the essential mode of action for various antibacterial compounds. Beside targeted interaction, an unspecific membrane binding or membrane insertion of drugs can contribute to the antibacterial activity by changing the lateral order of membrane constituents or by interfering with the membrane barrier function. Those pleiotropic effects are hardly to illustrate in the bacterial systems and need a detailed view at the in vitro level. Here, we illustrate the usefulness of a SAW biosensor in combination with model membranes to investigate the mode of membrane interaction of antibiotic active peptides. Using two different peptides we exemplary describe the interaction analysis in a two-step gain of information: (1) a binding intensity or affinity by analyzing the phase changes of oscillation, and (2) mode of membrane interaction, i.e., surface binding or internalization of the peptide by following the amplitude of oscillation.

  17. Analytic central path, sensitivity analysis and parametric linear programming

    NARCIS (Netherlands)

    A.G. Holder; J.F. Sturm; S. Zhang (Shuzhong)

    1998-01-01

    textabstractIn this paper we consider properties of the central path and the analytic center of the optimal face in the context of parametric linear programming. We first show that if the right-hand side vector of a standard linear program is perturbed, then the analytic center of the optimal face

  18. Metallic superhydrophobic surfaces via thermal sensitization

    Science.gov (United States)

    Vahabi, Hamed; Wang, Wei; Popat, Ketul C.; Kwon, Gibum; Holland, Troy B.; Kota, Arun K.

    2017-06-01

    Superhydrophobic surfaces (i.e., surfaces extremely repellent to water) allow water droplets to bead up and easily roll off from the surface. While a few methods have been developed to fabricate metallic superhydrophobic surfaces, these methods typically involve expensive equipment, environmental hazards, or multi-step processes. In this work, we developed a universal, scalable, solvent-free, one-step methodology based on thermal sensitization to create appropriate surface texture and fabricate metallic superhydrophobic surfaces. To demonstrate the feasibility of our methodology and elucidate the underlying mechanism, we fabricated superhydrophobic surfaces using ferritic (430) and austenitic (316) stainless steels (representative alloys) with roll off angles as low as 4° and 7°, respectively. We envision that our approach will enable the fabrication of superhydrophobic metal alloys for a wide range of civilian and military applications.

  19. Uncertainty and Sensitivity in Surface Dynamics Modeling

    Science.gov (United States)

    Kettner, Albert J.; Syvitski, James P. M.

    2016-05-01

    Papers for this special issue on 'Uncertainty and Sensitivity in Surface Dynamics Modeling' heralds from papers submitted after the 2014 annual meeting of the Community Surface Dynamics Modeling System or CSDMS. CSDMS facilitates a diverse community of experts (now in 68 countries) that collectively investigate the Earth's surface-the dynamic interface between lithosphere, hydrosphere, cryosphere, and atmosphere, by promoting, developing, supporting and disseminating integrated open source software modules. By organizing more than 1500 researchers, CSDMS has the privilege of identifying community strengths and weaknesses in the practice of software development. We recognize, for example, that progress has been slow on identifying and quantifying uncertainty and sensitivity in numerical modeling of earth's surface dynamics. This special issue is meant to raise awareness for these important subjects and highlight state-of-the-art progress.

  20. Analytic central path, sensitivity analysis and parametric linear programming

    OpenAIRE

    A.G. Holder; Sturm, J.F.; Zhang, Shuzhong

    1998-01-01

    textabstractIn this paper we consider properties of the central path and the analytic center of the optimal face in the context of parametric linear programming. We first show that if the right-hand side vector of a standard linear program is perturbed, then the analytic center of the optimal face is one-side differentiable with respect to the perturbation parameter. In that case we also show that the whole analytic central path shifts in a uniform fashion. When the objective vector is pertur...

  1. Mineral saturation states in natural waters and their sensitivity to thermodynamic and analytic errors

    Science.gov (United States)

    Nordstrom, D.K.; Ball, J.W.

    1989-01-01

    Saturation indices computed with WATEQ4F for chemical analyses from a groundwater in crystalline bedrock and a surface water receiving acid mine drainage are frequently at or above saturation with respect to calcite, fluorite, barite, gibbsite and ferrihydrite. A sensitivity analysis has been performed by varying the analytic and thermodynamic parameters for which the saturation indices are most sensitive. For calcite, fluorite and barite, the supersaturation effect appears to be real because it is only slightly decreased by sources of uncertainty. Apparent supersaturation for gibbsite is most likely caused by the degree of crystallinity on solubility behavior. Apparent supersaturation for ferric hydroxide is likely caused by small colloidal particles (<0.1 ??m) in the water sample that cannot be removed by standard field filtration, although several other possible explanations cannot be easily excluded. -from Authors

  2. Sensitivity of aerosol retrieval over snow surfaces

    Science.gov (United States)

    Seidel, F. C.; Painter, T. H.

    2011-12-01

    Significant amounts of black carbon and dust aerosols are transported to and accumulated in snowpacks of mountain ranges around the globe. The direct climate forcing of these particles is increasingly understood, whereas its indirect radiative forcing due to snow albedo and snow cover changes is still under investigation. In-situ and new remote sensing techniques are used to estimate snowpack properties from local to regional scales. Nevertheless, orbital and suborbital Earth observation data are difficult to analyze due to high spatial variability of the snowpack in rugged terrain. In addition, changes in atmospheric turbidity significantly complicate the estimation of snow cover characteristics and requires prior retrieval of optical and microphysical aerosol properties. Unfortunately, most aerosol retrieval techniques work only over dark surfaces. We therefore present a study on the sensitivity of aerosol optical depth (AOD) retrieval over snow surfaces. Radiative transfer calculations show that the sensitivity to surface spectral albedo depends strongly on the aerosol single scattering albedo (ratio of scattering efficiency to total extinction efficiency). Absorbing aerosol types (e.g. soot) provide a relatively good AOD retrieval sensitivity for very bright surfaces. The findings provide a basis for the development of future techniques and algorithms, which are able to concurrently retrieve snow and aerosol properties using remote sensing data. We explore these sensitivities with synthetic data and a time series of imaging spectrometer data, in situ spectral irradiance measurements, and sunphotometer measurements of AOD in the mountains of the Upper Colorado River Basin, USA. Ultimately, this research is important to map and better understand regional influences of aerosol and climate forcings on the cryosphere and water cycle in mountainous and other cold regions.

  3. Usage of analytical diagnostics when evaluating functional surface material defects

    Directory of Open Access Journals (Sweden)

    R. Frischer

    2015-10-01

    Full Text Available There are occurring defects due to defects mechanisms on parts of production devices surfaces. Outer defects pronouncement is changing throw the time with unequal speed. This variability of defect’s mechanism development cause that is impossible to evaluate technical state of the device in any moment, without the necessary underlying information. Proposed model is based on analytical diagnostics basis. Stochastic model with usage of Weibull probability distribution can assign probability of function surface defect occurrence on the operational information in any moment basis. The knowledge of defect range limiting moment, then enable when and in what range will be necessary to make renewal.

  4. Haze of surface random systems: An approximate analytic approach

    CERN Document Server

    Simonsen, Ingve; Andreassen, Erik; Ommundsen, Espen; Nord-Varhaug, Katrin

    2009-01-01

    Approximate analytic expressions for haze (and gloss) of Gaussian randomly rough surfaces for various types of correlation functions are derived within phase-perturbation theory. The approximations depend on the angle of incidence, polarization of the incident light, the surface roughness, $\\sigma$, and the average of the power spectrum taken over a small angular interval about the specular direction. In particular it is demonstrated that haze(gloss) increase(decrease) with $\\sigma/\\lambda$ as $\\exp(-A(\\sigma/\\lambda)^2)$ and decreases(increase) with $a/\\lambda$, where $a$ is the correlation length of the surface roughness, in a way that depends on the specific form of the correlation function being considered. These approximations are compared to what can be obtained from a rigorous Monte Carlo simulation approach, and good agreement is found over large regions of parameter space. Some experimental results for the angular distribution of the transmitted light through polymer films, and their haze, are presen...

  5. Analytical study of surface states caused by the edge decoration

    Institute of Scientific and Technical Information of China (English)

    Zhao Yuan-Yuan; Li Wei; Tao Rui-Bao

    2012-01-01

    Analytical studies of the effect of edge decoration on the energy spectrum of semi-infinite one-dimensional (1D) model and zigzag edged graphene (ZEG) are presented by means of transfer matrix method,in the frame of which the conditions for the existence of edge states are determined.For 1D model,the zero-energy surface state occurs regardless of whether the decorations exist or not,while the non-zero-energy surface states can be induced and manipulated through adjusting the edge decoration.On the other hand,the case for the semi-infinite ZEG model with nearestneighbour interaction is discussed in the analogous way.The non-zero-energy surface states can be induced by the edge decoration and moreover,the ratio between the edge hopping and the bulk hopping amplitudes should be within a certain threshold.

  6. A Bayesian Multi-Level Factor Analytic Model of Consumer Price Sensitivities across Categories

    Science.gov (United States)

    Duvvuri, Sri Devi; Gruca, Thomas S.

    2010-01-01

    Identifying price sensitive consumers is an important problem in marketing. We develop a Bayesian multi-level factor analytic model of the covariation among household-level price sensitivities across product categories that are substitutes. Based on a multivariate probit model of category incidence, this framework also allows the researcher to…

  7. The efficacy of cognitive-behavioral interventions for reducing anxiety sensitivity: A meta-analytic review

    NARCIS (Netherlands)

    Smits, J.A.J.; Berry, A.C.; Tart, C.D.; Powers, M.B.

    2008-01-01

    The present study meta-analytically reviewed the efficacy of cognitive-behavioral therapy (CBT) vs. control conditions in the reduction of anxiety sensitivity. A computerized search was conducted to indentify CBT outcome studies that included the Anxiety Sensitivity Index as a dependent variable. Of

  8. A Bayesian Multi-Level Factor Analytic Model of Consumer Price Sensitivities across Categories

    Science.gov (United States)

    Duvvuri, Sri Devi; Gruca, Thomas S.

    2010-01-01

    Identifying price sensitive consumers is an important problem in marketing. We develop a Bayesian multi-level factor analytic model of the covariation among household-level price sensitivities across product categories that are substitutes. Based on a multivariate probit model of category incidence, this framework also allows the researcher to…

  9. Analysis III analytic and differential functions, manifolds and Riemann surfaces

    CERN Document Server

    Godement, Roger

    2015-01-01

    Volume III sets out classical Cauchy theory. It is much more geared towards its innumerable applications than towards a more or less complete theory of analytic functions. Cauchy-type curvilinear integrals are then shown to generalize to any number of real variables (differential forms, Stokes-type formulas). The fundamentals of the theory of manifolds are then presented, mainly to provide the reader with a "canonical'' language and with some important theorems (change of variables in integration, differential equations). A final chapter shows how these theorems can be used to construct the compact Riemann surface of an algebraic function, a subject that is rarely addressed in the general literature though it only requires elementary techniques. Besides the Lebesgue integral, Volume IV will set out a piece of specialized mathematics towards which the entire content of the previous volumes will converge: Jacobi, Riemann, Dedekind series and infinite products, elliptic functions, classical theory of modular fun...

  10. Advantages of analytically computing the ground heat flux in land surface models

    Science.gov (United States)

    Pauwels, Valentijn R. N.; Daly, Edoardo

    2016-11-01

    It is generally accepted that the ground heat flux accounts for a significant fraction of the surface energy balance. In land surface models, the ground heat flux is typically estimated through a numerical solution of the heat conduction equation. Recent research has shown that this approach introduces errors in the estimation of the energy balance. In this paper, we calibrate a land surface model using a numerical solution of the heat conduction equation with four different vertical spatial resolutions. It is found that the thermal conductivity is the most sensitive parameter to the spatial resolution. More importantly, the thermal conductivity values are directly related to the spatial resolution, thus rendering any physical interpretation of this value irrelevant. The numerical solution is then replaced by an analytical solution. The results of the numerical and analytical solutions are identical when fine spatial and temporal resolutions are used. However, when using resolutions that are typical of land surface models, significant differences are found. When using the analytical solution, the ground heat flux is directly calculated without calculating the soil temperature profile. The calculation of the temperature at each node in the soil profile is thus no longer required, unless the model contains parameters that depend on the soil temperature, which in this study is not the case. The calibration is repeated, and thermal conductivity values independent of the vertical spatial resolution are obtained. The main conclusion of this study is that care must be taken when interpreting land surface model results that have been obtained using numerical ground heat flux estimates. The use of exact analytical solutions, when available, is recommended.

  11. Surface plasmon resonance biosensor for enzymatic detection of small analytes

    Science.gov (United States)

    Massumi Miyazaki, Celina; Makoto Shimizu, Flávio; Mejía-Salazar, J. R.; Oliveira, Osvaldo N., Jr.; Ferreira, Marystela

    2017-04-01

    Surface plasmon resonance (SPR) biosensing is based on the detection of small changes in the refractive index on a gold surface modified with molecular recognition materials, thus being mostly limited to detecting large molecules. In this paper, we report on a SPR biosensing platform suitable to detect small molecules by making use of the mediator-type enzyme microperoxidase-11 (MP11) in layer-by-layer films. By depositing a top layer of glucose oxidase or uricase, we were able to detect glucose or uric acid with limits of detection of 3.4 and 0.27 μmol l‑1, respectively. Measurable SPR signals could be achieved because of the changes in polarizability of MP11, as it is oxidized upon interaction with the analyte. Confirmation of this hypothesis was obtained with finite difference time domain simulations, which also allowed us to discard the possible effects from film roughness changes observed in atomic force microscopy images. The main advantage of this mediator-type enzyme approach is in the simplicity of the experimental method that does not require an external potential, unlike similar approaches for SPR biosensing of small molecules. The detection limits reported here were achieved without optimizing the film architecture, and therefore the performance can in principle be further enhanced, while the proposed SPR platform may be extended to any system where hydrogen peroxide is generated in enzymatic reactions.

  12. Analytical analysis of the Pennes bioheat transfer equation with sinusoidal heat flux condition on skin surface.

    Science.gov (United States)

    Shih, Tzu-Ching; Yuan, Ping; Lin, Win-Li; Kou, Hong-Sen

    2007-11-01

    This study focuses on the effect of the temperature response of a semi-infinite biological tissue due to a sinusoidal heat flux at the skin. The Pennes bioheat transfer equation such as rho(t)c(t)( partial differentialT/ partial differentialt)+W(b)c(b)(T-T(a))=k partial differential(2)T/ partial differentialx(2) with the oscillatory heat flux boundary condition such as q(0,t)=q(0)e(iomegat) was investigated. By using the Laplace transform, the analytical solution of the Pennes bioheat transfer equation with surface sinusoidal heating condition is found. This analytical expression is suitable for describing the transient temperature response of tissue for the whole time domain from the starting periodic oscillation to the final steady periodic oscillation. The results show that the temperature oscillation due to the sinusoidal heating on the skin surface is unstable in the initial period. Further, it is unavailable to predict the blood perfusion rate via the phase shifting between the surface heat flux and the surface temperature. Moreover, the lower frequency of sinusoidal heat flux on the skin surface induces a more sensitive phase shift response to the blood perfusion rate change, but extends the beginning time of sampling because of the avoidance of the unavailable first cyclic oscillation.

  13. An analytical sensitivity method for use in integrated aeroservoelastic aircraft design

    Science.gov (United States)

    Gilbert, Michael G.

    1989-01-01

    Interdisciplinary analysis capabilities have been developed for aeroservoelastic aircraft and large flexible spacecraft, but the requisite integrated design methods are only beginning to be developed. One integrated design method which has received attention is based on hierarchal problem decompositions, optimization, and design sensitivity analyses. This paper highlights a design sensitivity analysis method for Linear Quadratic Gaussian (LQG) optimal control laws, enabling the use of LQG techniques in the hierarchal design methodology. The LQG sensitivity analysis method calculates the change in the optimal control law and resulting controlled system responses due to changes in fixed design integration parameters using analytical sensitivity equations. Numerical results of a LQG design sensitivity analysis for a realistic aeroservoelastic aircraft example are presented. In this example, the sensitivity of the optimal control law and aircraft response for various parameters such as wing bending natural frequency is determined. The sensitivity results computed from the analytical expressions are used to estimate changes in response resulting from changes in the parameters. Comparisons of the estimates with exact calculated responses show they are reasonably accurate for + or - 15 percent changes in the parameters. Evaluation of the analytical expressions is computationally faster than equivalent finite difference calculations.

  14. Monitoring temperature and pressure over surfaces using sensitive paints

    Science.gov (United States)

    Guerrero-Viramontes, J. Ascención; Moreno Hernández, David; Mendoza Santoyo, Fernando; Morán Loza, José Miguel; García Arreola, Alicia

    2007-03-01

    Two techniques for monitoring temperature and pressure variations over surfaces using sensitive paints are presented. The analysis is done by the acquisition of a set of images of the surface under analysis. The surface is painted by a paint called Pressure Sensitive Paint (PSP) for pressure measurements and Temperature Sensitive Paints (TSP) for temperature measurements. These kinds of paints are deposited over the surface under analysis. The recent experimental advances in calibration process are presented in this paper.

  15. Analytical modelling for ultrasonic surface mechanical attrition treatment

    Directory of Open Access Journals (Sweden)

    Guan-Rong Huang

    2015-07-01

    Full Text Available The grain refinement, gradient structure, fatigue limit, hardness, and tensile strength of metallic materials can be effectively enhanced by ultrasonic surface mechanical attrition treatment (SMAT, however, never before has SMAT been treated with rigorous analytical modelling such as the connection among the input energy and power and resultant temperature of metallic materials subjected to SMAT. Therefore, a systematic SMAT model is actually needed. In this article, we have calculated the averaged speed, duration time of a cycle, kinetic energy and kinetic energy loss of flying balls in SMAT for structural metallic materials. The connection among the quantities such as the frequency and amplitude of attrition ultrasonic vibration motor, the diameter, mass and density of balls, the sample mass, and the height of chamber have been considered and modelled in details. And we have introduced the one-dimensional heat equation with heat source within uniform-distributed depth in estimating the temperature distribution and heat energy of sample. In this approach, there exists a condition for the frequency of flying balls reaching a steady speed. With these known quantities, we can estimate the strain rate, hardness, and grain size of sample.

  16. Sensitivity of surface acoustic wave devices

    Science.gov (United States)

    Filipiak, Jerzy; Zubko, Konrad

    2001-08-01

    The SAW devices are widely used as filters, delay lines, resonators and gas sensors. It is possible to use it as mechanical force. The paper describes sensitivity of acceleration sensor based on SAW using the Rayleigh wave propagation. Since characteristic of acceleration SAW sensors are largely determined by piezoelectric materials, it is very important to select substrate with required characteristics. Researches and numerical modeling based on simply sensor model include piezoelectric beam with unilateral free end. An aggregated mass is connected to the one. The dimension and aggregated mass are various. In this case a buckling stress and sensitivity are changed. Sensitivity in main and perpendicular axis are compare for three sensor based on SiO2, LiNbO3, Li2B4O7. Influences of phase velocity, electro-mechanical coupling constant and density on sensitivity are investigated. Some mechanical parameters of the substrates in dynamic work mode are researched using sensor model and Rayleigh model of vibrations without vibration damping. The model is useful because it simply determines dependencies between sensor parameters and substrate parameters. Differences between measured and evaluated quantities are less than 5 percent. Researches based on sensor modes, which fulfilled mechanical specifications similarly to aircraft navigation.

  17. Recent analytical applications of nanoparticle sensitized lucigenin and luminol chemiluminescent reactions

    Indian Academy of Sciences (India)

    S M Wabaidur; Mu Naushad; Z A Alothman

    2012-02-01

    There is an ever-increasing demand for rapid, sensitive, cost effective and selective detection methods for the analysis of many essential compounds.When chemiluminescence has been introduced to analytical chemistry as a detection technique, it has been shown to meet many of these requirements. This method has become a powerful tool for the determination of many compounds. Using this method, low detection limits can be obtained with simple and inexpensive instrumentation. Coupled with flow injection technique the method has become more popular for wider applications. Since many excellent reviews on the chemiluminogenic techniques have appeared in the literature in recent years, the present paper does not intend to cover the exhaustive studies in this area, but will selectively describe the analytical applications of nanoparticle sensitized lucigenin and luminol chemiluminescent reactions and evaluate their recent progress together with our present work.

  18. Toward Analytic Solution of Nonlinear Differential Difference Equations via Extended Sensitivity Approach

    Institute of Scientific and Technical Information of China (English)

    G. Darmani; S. Setayeshi; H. Ramezanpour

    2012-01-01

    In this paper an efficient computational method based on extending the sensitivity approach (SA) is proposed to find an analytic exact solution of nonlinear differential difference equations. In this manner we avoid solving the nonlinear problem directly. By extension of sensitivity approach for differential difference equations (DDEs), the nonlinear original problem is transformed into infinite linear differential difference equations, which should be solved in a recursive manner. Then the exact solution is determined in the form of infinite terms series and by intercepting series an approximate solution is obtained. Numerical examples are employed to show the effectiveness of the proposed approach.

  19. Analytical sensitivities and energies of thermal-neutron-capture gamma rays

    Science.gov (United States)

    Duffey, D.; El-Kady, A.; Senftle, F.E.

    1970-01-01

    A table of the analytical sensitivities of the principal lines in the thermal-neutron-capture gamma ray spectrum has been compiled for most of the elements. In addition a second table of the full-energy, single-escape, and double-escape peaks has been compiled according to energy for all significant lines above 3 MeV. Lines that contrast well with adjacent lines are noted as prominent. The tables are useful for spectral interpretation and calibration. ?? 1970.

  20. Analytical sensitivities and energies of thermal neutron capture gamma rays II

    Science.gov (United States)

    Senftle, F.E.; Moore, H.D.; Leep, D.B.; El-Kady, A.; Duffey, D.

    1971-01-01

    A table of the analytical sensitivities of the principal lines in the thermal neutron capture gamma-ray spectrum from 0 to 3 MeV has been compiled for most of the elements. A tabulation of the full-energy, single-escape, and double-escape peaks has also been made according to energy. The tables are useful for spectral interpretation and calibration. ?? 1971.

  1. Function-weighted frequency response function sensitivity method for analytical model updating

    Science.gov (United States)

    Lin, R. M.

    2017-09-01

    Since the frequency response function (FRF) sensitivity method was first proposed [26], it has since become a most powerful and practical method for analytical model updating. Nevertheless, the original formulation of the FRF sensitivity method does suffer the limitation that the initial analytical model to be updated should be reasonably close to the final updated model to be sought, due the assumed mathematical first order approximation implicit to most sensitivity based methods. Convergence to correct model is not guaranteed when large modelling errors exist and blind application often leads to optimal solutions which are truly sought. This paper seeks to examine all the important numerical characteristics of the original FRF sensitivity method including frequency data selection, numerical balance and convergence performance. To further improve the applicability of the method to cases of large modelling errors, a new novel function-weighted sensitivity method is developed. The new method has shown much superior performance on convergence even in the presence of large modelling errors. Extensive numerical case studies based on a mass-spring system and a GARTEUR structure have been conducted and very encouraging results have been achieved. Effect of measurement noise has been examined and the method works reasonably well in the presence of measurement uncertainties. The new method removes the restriction of modelling error magnitude being of second order in Euclidean norm as compared with that of system matrices, thereby making it a truly general method applicable to most practical model updating problems.

  2. Analytical Round Robin for Elastic-Plastic Analysis of Surface Cracked Plates: Phase I Results

    Science.gov (United States)

    Wells, D. N.; Allen, P. A.

    2012-01-01

    An analytical round robin for the elastic-plastic analysis of surface cracks in flat plates was conducted with 15 participants. Experimental results from a surface crack tension test in 2219-T8 aluminum plate provided the basis for the inter-laboratory study (ILS). The study proceeded in a blind fashion given that the analysis methodology was not specified to the participants, and key experimental results were withheld. This approach allowed the ILS to serve as a current measure of the state of the art for elastic-plastic fracture mechanics analysis. The analytical results and the associated methodologies were collected for comparison, and sources of variability were studied and isolated. The results of the study revealed that the J-integral analysis methodology using the domain integral method is robust, providing reliable J-integral values without being overly sensitive to modeling details. General modeling choices such as analysis code, model size (mesh density), crack tip meshing, or boundary conditions, were not found to be sources of significant variability. For analyses controlled only by far-field boundary conditions, the greatest source of variability in the J-integral assessment is introduced through the constitutive model. This variability can be substantially reduced by using crack mouth opening displacements to anchor the assessment. Conclusions provide recommendations for analysis standardization.

  3. Numerical analysis of a photonic crystal fiber based on a surface plasmon resonance sensor with an annular analyte channel

    Science.gov (United States)

    Liu, Chao; Yang, Lin; Su, Weiquan; Wang, Famei; Sun, Tao; Liu, Qiang; Mu, Haiwei; Chu, Paul K.

    2017-01-01

    A sensing structure is designed with a photonic crystal fiber based on a surface plasmon resonance (PCF-SPR) sensor using gold as the sensitive material. The benefit of the structure is to reduce the difficulty in gold deposition, because the Au film is deposited on the outside of the fiber core instead of on the holes filled with analyte inside the core. The properties of the sensor are numerically calculated by the finite element method. The results show that the thickness of the gold film, refractive index of the analyte, and radius of the central hole affect the sensing performance of the PCF-SPR. By optimizing the model, an extra graphene layer with the thickness of 20 nm is deposited on the gold film in the model. The maximum spectral sensitivity can be as high as 7500 nm/RIU for the sensor with the gold-graphene composite film as the sensitive material.

  4. Surface sensitivity of the spin Seebeck effect

    NARCIS (Netherlands)

    Aqeel, Aisha; Vera Marun, Ivan; van Wees, Bart; Palstra, Thomas

    2014-01-01

    We have investigated the influence of the interface quality on the spin Seebeck effect (SSE) of the bilayer system yttrium iron garnet (YIG)-platinum (Pt). The magnitude and shape of the SSE is strongly influenced by mechanical treatment of the YIG single crystal surface. We observe that the saturat

  5. Analytical sensitivity of four commonly used hCG point of care devices.

    Science.gov (United States)

    Kamer, Sandy M; Foley, Kevin F; Schmidt, Robert L; Greene, Dina N

    2015-04-01

    Point of care (POC) hCG assays are often used to rule-out pregnancy and therefore diagnostic sensitivity, especially at low concentrations of hCG, is important. There are very few studies in the literature that seek to verify the claimed analytical sensitivity of hCG POC devices. The analytical sensitivity of four commonly used hCG POC devices (Alere hCG Combo Cassette, ICON 20 hCG, OSOM hCG Combo Test, and Sure-Vue Serum/Urine hCG-STAT) was challenged using urine samples (n=50) selected based on quantitative hCG concentrations. The majority of these specimens (n=40) had an hCG concentration between 20 and 200 U/L. Each specimen/device combination was reviewed by three individuals. Statistical calculations were performed using Stata 12. The analytical sensitivity of the OSOM was significantly lower inferior than that of the other POC devices. There was no significant difference in the sensitivity of the Alere, ICON 20 and Sure-Vue devices. There was no significant difference in the individual interpretation of the hCG POC results. All hCG POC devices evaluated in this study were susceptible to false negative results at low concentrations of urine hCG. Laboratorians and clinicians should be aware that there are limitations when using urine hCG POC devices to rule out early pregnancy. Copyright © 2014 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.

  6. Associations between rejection sensitivity and mental health outcomes: A meta-analytic review.

    Science.gov (United States)

    Gao, Shuling; Assink, Mark; Cipriani, Andrea; Lin, Kangguang

    2017-08-15

    Rejection sensitivity is a personality disposition characterized by oversensitivity to social rejection. Using a three-level meta-analytic model, 75 studies were reviewed that examined associations between rejection sensitivity and five mental health outcomes: depression, anxiety, loneliness, borderline personality disorder, and body dysmorphic disorder. The results showed significant and moderate associations between rejection sensitivity and depression (pooled r=0.332; p<0.001), anxiety (pooled r=0.407; p<0.001), loneliness (pooled r=0.386; p<0.001), borderline personality disorder (pooled r=0.413; p<0.001), and body dysmorphic disorder (pooled r=0.428; p<0.001). The associations between rejection sensitivity and depression, anxiety, and borderline personality disorder varied by type of sample, but the associations were similar for clinical and non-clinical (i.e., community) samples. The association between rejection sensitivity and anxiety was negatively moderated by percentage of females in samples. The association between rejection sensitivity and depression was negatively moderated by length of follow-up. The longitudinal associations between rejection sensitivity and depression, anxiety, and loneliness were stable over time. Implications of the findings for both risk assessment and prevention and intervention strategies in mental health practice are discussed. Copyright © 2017. Published by Elsevier Ltd.

  7. Surface sensitivity of the spin Seebeck effect

    Energy Technology Data Exchange (ETDEWEB)

    Aqeel, A.; Vera-Marun, I. J.; Wees, B. J. van; Palstra, T. T. M., E-mail: t.t.m.palstra@rug.nl [Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen (Netherlands)

    2014-10-21

    We have investigated the influence of the interface quality on the spin Seebeck effect (SSE) of the bilayer system yttrium iron garnet (YIG)–platinum (Pt). The magnitude and shape of the SSE is strongly influenced by mechanical treatment of the YIG single crystal surface. We observe that the saturation magnetic field (H{sub sat}{sup SSE}) for the SSE signal increases from 55.3 mT to 72.8 mT with mechanical treatment. The change in the magnitude of H{sub sat}{sup SSE} can be attributed to the presence of a perpendicular magnetic anisotropy due to the treatment induced surface strain or shape anisotropy in the Pt/YIG system. Our results show that the SSE is a powerful tool to investigate magnetic anisotropy at the interface.

  8. [Sensitivity of surface microorganisms to disinfectants].

    Science.gov (United States)

    Krzywicka, H; Janowska, J; Tadeusiak, B

    1991-01-01

    The influence of humidity and temperature on survival of S. aureus and P. aeruginosa on the surfaces of titles, glass and blanket carriers has been estimated. The number of CFU was examined after exposure time 6 and 24 hours in temperatures of 21 degrees C, 37 degrees C and RH 35%, 95%. It was observed: 1. The important reduction of numbers of both microorganisms at temperature 37 degrees C and RH 95%, 2. The relatively high number of survival cells of P. aeruginosa on the surface of blankets at temp. 21 degrees C and RH 95%. The microorganisms on the carriers were previously kept for 24 h at temp. 21 degrees C, RH 35% and 95% and then exposed to solutions of chloramine, formalin, lysol and Sterinol (QAC). It was observed that there was a great dependence of the disinfecting effect on the degree of dessication of the surfaces. In all cases the resistance of contaminated carriers stored 24 h was higher at 95% RH than at 35% RH.

  9. Photonic crystal fiber-based surface plasmon resonance sensor with selective analyte channels and graphene-silver deposited core.

    Science.gov (United States)

    Rifat, Ahmmed A; Mahdiraji, G Amouzad; Chow, Desmond M; Shee, Yu Gang; Ahmed, Rajib; Adikan, Faisal Rafiq Mahamd

    2015-05-19

    We propose a surface plasmon resonance (SPR) sensor based on photonic crystal fiber (PCF) with selectively filled analyte channels. Silver is used as the plasmonic material to accurately detect the analytes and is coated with a thin graphene layer to prevent oxidation. The liquid-filled cores are placed near to the metallic channel for easy excitation of free electrons to produce surface plasmon waves (SPWs). Surface plasmons along the metal surface are excited with a leaky Gaussian-like core guided mode. Numerical investigations of the fiber's properties and sensing performance are performed using the finite element method (FEM). The proposed sensor shows maximum amplitude sensitivity of 418 Refractive Index Units (RIU-1) with resolution as high as 2.4 × 10(-5) RIU. Using the wavelength interrogation method, a maximum refractive index (RI) sensitivity of 3000 nm/RIU in the sensing range of 1.46-1.49 is achieved. The proposed sensor is suitable for detecting various high RI chemicals, biochemical and organic chemical analytes. Additionally, the effects of fiber structural parameters on the properties of plasmonic excitation are investigated and optimized for sensing performance as well as reducing the sensor's footprint.

  10. Photonic Crystal Fiber-Based Surface Plasmon Resonance Sensor with Selective Analyte Channels and Graphene-Silver Deposited Core

    Directory of Open Access Journals (Sweden)

    Ahmmed A. Rifat

    2015-05-01

    Full Text Available We propose a surface plasmon resonance (SPR sensor based on photonic crystal fiber (PCF with selectively filled analyte channels. Silver is used as the plasmonic material to accurately detect the analytes and is coated with a thin graphene layer to prevent oxidation. The liquid-filled cores are placed near to the metallic channel for easy excitation of free electrons to produce surface plasmon waves (SPWs. Surface plasmons along the metal surface are excited with a leaky Gaussian-like core guided mode. Numerical investigations of the fiber’s properties and sensing performance are performed using the finite element method (FEM. The proposed sensor shows maximum amplitude sensitivity of 418 Refractive Index Units (RIU−1 with resolution as high as 2.4 × 10−5 RIU. Using the wavelength interrogation method, a maximum refractive index (RI sensitivity of 3000 nm/RIU in the sensing range of 1.46–1.49 is achieved. The proposed sensor is suitable for detecting various high RI chemicals, biochemical and organic chemical analytes. Additionally, the effects of fiber structural parameters on the properties of plasmonic excitation are investigated and optimized for sensing performance as well as reducing the sensor’s footprint.

  11. Photonic Crystal Fiber-Based Surface Plasmon Resonance Sensor with Selective Analyte Channels and Graphene-Silver Deposited Core

    Science.gov (United States)

    Rifat, Ahmmed A.; Mahdiraji, G. Amouzad; Chow, Desmond M.; Shee, Yu Gang; Ahmed, Rajib; Adikan, Faisal Rafiq Mahamd

    2015-01-01

    We propose a surface plasmon resonance (SPR) sensor based on photonic crystal fiber (PCF) with selectively filled analyte channels. Silver is used as the plasmonic material to accurately detect the analytes and is coated with a thin graphene layer to prevent oxidation. The liquid-filled cores are placed near to the metallic channel for easy excitation of free electrons to produce surface plasmon waves (SPWs). Surface plasmons along the metal surface are excited with a leaky Gaussian-like core guided mode. Numerical investigations of the fiber’s properties and sensing performance are performed using the finite element method (FEM). The proposed sensor shows maximum amplitude sensitivity of 418 Refractive Index Units (RIU−1) with resolution as high as 2.4 × 10−5 RIU. Using the wavelength interrogation method, a maximum refractive index (RI) sensitivity of 3000 nm/RIU in the sensing range of 1.46–1.49 is achieved. The proposed sensor is suitable for detecting various high RI chemicals, biochemical and organic chemical analytes. Additionally, the effects of fiber structural parameters on the properties of plasmonic excitation are investigated and optimized for sensing performance as well as reducing the sensor’s footprint. PMID:25996510

  12. Engineering of Surface Chemistry for Enhanced Sensitivity in Nanoporous Interferometric Sensing Platforms.

    Science.gov (United States)

    Law, Cheryl Suwen; Sylvia, Georgina M; Nemati, Madieh; Yu, Jingxian; Losic, Dusan; Abell, Andrew D; Santos, Abel

    2017-03-15

    We explore new approaches to engineering the surface chemistry of interferometric sensing platforms based on nanoporous anodic alumina (NAA) and reflectometric interference spectroscopy (RIfS). Two surface engineering strategies are presented, namely (i) selective chemical functionalization of the inner surface of NAA pores with amine-terminated thiol molecules and (ii) selective chemical functionalization of the top surface of NAA with dithiol molecules. The strong molecular interaction of Au(3+) ions with thiol-containing functional molecules of alkane chain or peptide character provides a model sensing system with which to assess the sensitivity of these NAA platforms by both molecular feature and surface engineering. Changes in the effective optical thickness of the functionalized NAA photonic films (i.e., sensing principle), in response to gold ions, are monitored in real-time by RIfS. 6-Amino-1-hexanethiol (inner surface) and 1,6-hexanedithiol (top surface), the most sensitive functional molecules from approaches i and ii, respectively, were combined into a third sensing strategy whereby the NAA platforms are functionalized on both the top and inner surfaces concurrently. Engineering of the surface according to this approach resulted in an additive enhancement in sensitivity of up to 5-fold compared to previously reported systems. This study advances the rational engineering of surface chemistry for interferometric sensing on nanoporous platforms with potential applications for real-time monitoring of multiple analytes in dynamic environments.

  13. Boron doped diamond sensor for sensitive determination of metronidazole: Mechanistic and analytical study by cyclic voltammetry and square wave voltammetry

    Energy Technology Data Exchange (ETDEWEB)

    Ammar, Hafedh Belhadj, E-mail: hbelhadjammar@yahoo.fr; Brahim, Mabrouk Ben; Abdelhédi, Ridha; Samet, Youssef

    2016-02-01

    The performance of boron-doped diamond (BDD) electrode for the detection of metronidazole (MTZ) as the most important drug of the group of 5-nitroimidazole was proven using cyclic voltammetry (CV) and square wave voltammetry (SWV) techniques. A comparison study between BDD, glassy carbon and silver electrodes on the electrochemical response was carried out. The process is pH-dependent. In neutral and alkaline media, one irreversible reduction peak related to the hydroxylamine derivative formation was registered, involving a total of four electrons. In acidic medium, a prepeak appears probably related to the adsorption affinity of hydroxylamine at the electrode surface. The BDD electrode showed higher sensitivity and reproducibility analytical response, compared with the other electrodes. The higher reduction peak current was registered at pH 11. Under optimal conditions, a linear analytical curve was obtained for the MTZ concentration in the range of 0.2–4.2 μmol L{sup −1}, with a detection limit of 0.065 μmol L{sup −1}. - Highlights: • SWV for the determination of MTZ • Boron-doped diamond as a new electrochemical sensor • Simple and rapid detection of MTZ • Efficiency of BDD for sensitive determination of MTZ.

  14. Analytical performance of molecular beacons on surface immobilized gold nanoparticles of varying size and density.

    Science.gov (United States)

    Uddayasankar, Uvaraj; Krull, Ulrich J

    2013-11-25

    The high quenching efficiency of metal nanoparticles has facilitated its use as quenchers in molecular beacons. To optimize this system, a good understanding of the many factors that influence molecular beacon performance is required. In this study, molecular beacon performance was evaluated as a function of gold nanoparticle size and its immobilization characteristics. Gold nanoparticles of 4 nm, 15 nm and 87 nm diameter, were immobilized onto glass slides. Each size regime offered distinctive optical properties for fluorescence quenching of molecular dyes that were conjugated to oligonucleotides that were immobilized to the gold nanoparticles. Rigid double stranded DNA was used as a model to place fluorophores at different distances from the gold nanoparticles. The effect of particle size and also the immobilization density of nanoparticles was evaluated. The 4 nm and 87 nm gold nanoparticles offered the highest sensitivity in terms of the change in fluorescence intensity as a function of distance (3-fold improvement for Cy5). The optical properties of the molecular fluorophore was of significance, with Cy5 offering higher contrast ratios than Cy3 due to the red-shifted emission spectrum relative to the plasmon peak. A high density of gold nanoparticles reduced contrast ratios, indicating preference for a monolayer of immobilized nanoparticles when considering analytical performance. Molecular beacon probes were then used in place of the double stranded oligonucleotides. There was a strong dependence of molecular beacon performance on the length of a linker used for attachment to the nanoparticle surface. The optimal optical performance was obtained with 4 nm gold nanoparticles that were immobilized as monolayers of low density (5.7×10(11)particles cm(-2)) on glass surfaces. These nanoparticle surfaces offered a 2-fold improvement in analytical performance of the molecular beacons when compared to other nanoparticle sizes investigated. The principles developed

  15. Intracavity optogalvanic spectroscopy. An analytical technique for 14C analysis with subattomole sensitivity.

    Science.gov (United States)

    Murnick, Daniel E; Dogru, Ozgur; Ilkmen, Erhan

    2008-07-01

    We show a new ultrasensitive laser-based analytical technique, intracavity optogalvanic spectroscopy, allowing extremely high sensitivity for detection of (14)C-labeled carbon dioxide. Capable of replacing large accelerator mass spectrometers, the technique quantifies attomoles of (14)C in submicrogram samples. Based on the specificity of narrow laser resonances coupled with the sensitivity provided by standing waves in an optical cavity and detection via impedance variations, limits of detection near 10(-15) (14)C/(12)C ratios are obtained. Using a 15-W (14)CO2 laser, a linear calibration with samples from 10(-15) to >1.5 x 10(-12) in (14)C/(12)C ratios, as determined by accelerator mass spectrometry, is demonstrated. Possible applications include microdosing studies in drug development, individualized subtherapeutic tests of drug metabolism, carbon dating and real time monitoring of atmospheric radiocarbon. The method can also be applied to detection of other trace entities.

  16. Quasi-analytical solutions of hybrid platform and the optimization of highly sensitive thin-film sensors for terahertz radiation

    CERN Document Server

    Tapsanit, Piyawath; Ishihara, Teruya; Otani, Chiko

    2016-01-01

    We present quasi-analytical solutions (QANS) of hybrid platform (HP) comprising metallic grating (MG) and stacked-dielectric layers for terahertz (THz) radiation. The QANS are validated by finite difference time domain simulation. It is found that the Wood anomalies induce the high-order spoof surface plasmon resonances in the HP. The QANS are applied to optimize new perfect absorber for THz sensing of large-area thin film with ultrahigh figure of merit reaching fifth order of magnitude for the film thickness 0.0001p (p: MG period). The first-order Wood's anomaly of the insulator layer and the Fabry-Perot in the slit's cavity account for the resonance of the perfect absorber. The QANS and the new perfect absorber may lead to highly sensitive and practical nano-film refractive index sensor for THz radiation.

  17. Linear Analytical Solutions of Mechanical Sensitivity in Large Deflection of Unsymmetrically Layered Piezoelectric Plate under Pretension

    Directory of Open Access Journals (Sweden)

    Chun-Fu Chen

    2014-03-01

    Full Text Available Linear analytical study on the mechanical sensitivity in large deflection of unsymmetrically layered and laterally loaded piezoelectric plate under pretension is conducted. von Karman plate theory for large deflection is utilized but extended to the case of an unsymmetrically layered plate embedded with a piezoelectric layer. The governing equations thus obtained are simplified by omitting the arising nonlinear terms, yielding a Bessel or modified Bessel equation for the lateral slope. Depending on the relative magnitude of the piezoelectric effect, for both cases, analytical solutions of various geometrical responses are developed and formulated via Bessel and modified Bessel functions. The associated ultimate radial stresses are further derived following lamina constitutive law to evaluate the mechanical sensitivity of the considered plate. For a nearly monolithic plate under a very low applied voltage, the results are in good agreement with those for a single-layered case due to pure mechanical load available in literature, and thus the present approach is checked. For a two-layered unsymmetric plate made of typical silicon-based materials, a sound piezoelectric effect is illustrated particularly in a low pretension condition.

  18. Sensitivity of the NMR density matrix to pulse sequence parameters: a simplified analytic approach.

    Science.gov (United States)

    Momot, Konstantin I; Takegoshi, K

    2012-08-01

    We present a formalism for the analysis of sensitivity of nuclear magnetic resonance pulse sequences to variations of pulse sequence parameters, such as radiofrequency pulses, gradient pulses or evolution delays. The formalism enables the calculation of compact, analytic expressions for the derivatives of the density matrix and the observed signal with respect to the parameters varied. The analysis is based on two constructs computed in the course of modified density-matrix simulations: the error interrogation operators and error commutators. The approach presented is consequently named the Error Commutator Formalism (ECF). It is used to evaluate the sensitivity of the density matrix to parameter variation based on the simulations carried out for the ideal parameters, obviating the need for finite-difference calculations of signal errors. The ECF analysis therefore carries a computational cost comparable to a single density-matrix or product-operator simulation. Its application is illustrated using a number of examples from basic NMR spectroscopy. We show that the strength of the ECF is its ability to provide analytic insights into the propagation of errors through pulse sequences and the behaviour of signal errors under phase cycling. Furthermore, the approach is algorithmic and easily amenable to implementation in the form of a programming code. It is envisaged that it could be incorporated into standard NMR product-operator simulation packages.

  19. ICL-Based OF-CEAS: A Sensitive Tool for Analytical Chemistry.

    Science.gov (United States)

    Manfred, Katherine M; Hunter, Katharine M; Ciaffoni, Luca; Ritchie, Grant A D

    2017-01-03

    Optical-feedback cavity-enhanced absorption spectroscopy (OF-CEAS) using mid-infrared interband cascade lasers (ICLs) is a sensitive technique for trace gas sensing. The setup of a V-shaped optical cavity operating with a 3.29 μm cw ICL is detailed, and a quantitative characterization of the injection efficiency, locking stability, mode matching, and detection sensitivity is presented. The experimental data are supported by a model to show how optical feedback affects the laser frequency as it is scanned across several longitudinal modes of the optical cavity. The model predicts that feedback enhancement effects under strongly absorbing conditions can cause underestimations in the measured absorption, and these predictions are verified experimentally. The technique is then used in application to the detection of nitrous oxide as an exemplar of the utility of this technique for analytical gas phase spectroscopy. The analytical performance of the spectrometer, expressed as noise equivalent absorption coefficient, was estimated as 4.9 × 10(-9) cm (-1) Hz(-1/2), which compares well with recently reported values.

  20. Analytic methods for predicting biosettlement on patterned surfaces

    Science.gov (United States)

    Long, Christopher James

    Marine organism fouling of surfaces has significant impact on our environment and the economy. Increased fuel use due to drag costs approximately $600 million annually in the United States alone. The efficiency of marine vessels substantially decreases due to fouling. Toxins in some antifouling paints accumulate in the marine environment and produce negative effects on the marine ecology. There is a critical need for effective non-toxic, anti-fouling, marine coatings that reduce operational costs and the overall environmental impact of ocean vessels on the environment. Our approach is to investigate the interaction between the wettability of surfaces with the response of fouling organisms. One of the ways the wettability can be influenced is through the use of topography. Since the topographies have directionality, the direction dependence of the wettability was determined on several microscale topographies that have previously shown antifouling potential. Breaking microscale ridges into the discontinuous features in the antifouling topographies reduced the anisotropies in the contact angles, but did not eliminate anisotropy. The number of distinct features in the design and the area fraction of the topographic features were found to influence settlement of the fouling alga Ulva linza. A biosettlement model, refined from previous work, predicts the settlement of Ulva linza to three previously untested surfaces. These surfaces significantly reduced the settlement of these spores in vitro by up to 78%. The attachment of another species of fouler, the diatom Navicula perminuta, was reduced by approximately 35% on several surfaces that reduced Ulva linza settlement. The Navicula cells responded differently to the topographies than the Ulva linza spores. A mapping technique was developed to determine the two-dimensional settlement pattern of cells on the topographical surfaces. This technique revealed and quantified several preferential locations for Ulva linza

  1. Multi-parameter singular Radon transforms III: real analytic surfaces

    CERN Document Server

    Stein, Elias M

    2011-01-01

    The goal of this paper is to study operators of the form, \\[ Tf(x)= \\psi(x)\\int f(\\gamma_t(x))K(t)\\: dt, \\] where $\\gamma$ is a real analytic function defined on a neighborhood of the origin in $(t,x)\\in \\R^N\\times \\R^n$, satisfying $\\gamma_0(x)\\equiv x$, $\\psi$ is a cutoff function supported near $0\\in \\R^n$, and $K$ is a "multi-parameter singular kernel" supported near $0\\in \\R^N$. A main example is when $K$ is a "product kernel." We also study maximal operators of the form, \\[ \\mathcal{M} f(x) = \\psi(x)\\sup_{0<\\delta_1,..., \\delta_N<<1} \\int_{|t|<1} |f(\\gamma_{\\delta_1 t_1,...,\\delta_N t_N}(x))|\\: dt. \\] We show that $\\mathcal{M}$ is bounded on $L^p$ ($1

  2. European multicenter analytical evaluation of the Abbott ARCHITECT STAT high sensitive troponin I immunoassay

    DEFF Research Database (Denmark)

    Krintus, Magdalena; Kozinski, Marek; Boudry, Pascal

    2014-01-01

    high sensitive cardiac troponin I (hs-cTnI) assay and its 99th percentile upper reference limit (URL). METHODS: Laboratories from nine European countries evaluated the ARCHITECT STAT high sensitive troponin I (hs-TnI) immunoassay on the ARCHITECT i2000SR/i1000SR immunoanalyzers. Imprecision, limit...... hs-cTnI assay and contemporary cTnI assay at 99th percentile cut-off was found to be 95%. TnI was detectable in 75% and 57% of the apparently healthy population using the lower (1.1 ng/L) and upper (1.9 ng/L) limit of the LoD range provided by the ARCHITECT STAT hs-TnI package insert, respectively....... The 99th percentile values were gender dependent. CONCLUSIONS: The new ARCHITECT STAT hs-TnI assay with improved analytical features meets the criteria of high sensitive Tn test and will be a valuable diagnostic tool....

  3. Interfacial characterization and analytical applications of chemically-modified surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jianhong [Iowa State Univ., Ames, IA (United States)

    1998-02-23

    The goal of this work is to explore several new strategies and approaches to the surface modification and the microscopic characterization of interfaces in the areas mainly targeting sensor technologies that are of interest to environmental control or monitoring, and scanning probe microscopies techniques that can monitor interfacial chemical reactions in real time. Centered on the main theme, four specific topics are presented as four chapters in this dissertation following the general introduction. Chapter 1 describes the development of two immobilization schemes for covalently immobilizing fluoresceinamine at cellulose acetate and its application as a pH sensing film. Chapter 2 investigates the applicability of SFM to following the base-hydrolysis of a dithio-bis(succinimidylundecanoate) monolayer at gold in situ. Chapter 3 studies the mechanism for the accelerated rate of hydrolysis of the dithio-bis(succinimidylundecanoate) monolayer at Au(111) surface. Chapter 4 focuses on the development of an electrochemical approach to the elimination of chloride interference in Chemical Oxygen Demand (COD) analysis of waste water. The procedures, results and conclusions are described in each chapter. This report contains the introduction, references, and general conclusions. Chapters have been processed separately for inclusion on the data base. 95 refs.

  4. Boron doped diamond sensor for sensitive determination of metronidazole: Mechanistic and analytical study by cyclic voltammetry and square wave voltammetry.

    Science.gov (United States)

    Ammar, Hafedh Belhadj; Brahim, Mabrouk Ben; Abdelhédi, Ridha; Samet, Youssef

    2016-02-01

    The performance of boron-doped diamond (BDD) electrode for the detection of metronidazole (MTZ) as the most important drug of the group of 5-nitroimidazole was proven using cyclic voltammetry (CV) and square wave voltammetry (SWV) techniques. A comparison study between BDD, glassy carbon and silver electrodes on the electrochemical response was carried out. The process is pH-dependent. In neutral and alkaline media, one irreversible reduction peak related to the hydroxylamine derivative formation was registered, involving a total of four electrons. In acidic medium, a prepeak appears probably related to the adsorption affinity of hydroxylamine at the electrode surface. The BDD electrode showed higher sensitivity and reproducibility analytical response, compared with the other electrodes. The higher reduction peak current was registered at pH11. Under optimal conditions, a linear analytical curve was obtained for the MTZ concentration in the range of 0.2-4.2μmolL(-1), with a detection limit of 0.065μmolL(-1). Copyright © 2015 Elsevier B.V. All rights reserved.

  5. Surface reactivity of minerals illustrated by observations from surface analytical techniques

    Energy Technology Data Exchange (ETDEWEB)

    Stipp, S.L.S. [Copenhagen Univ., Copenhagen (Denmark). Interface Geochemistry, Geological Institute

    2000-07-01

    Over the decades that geochemists have been studying solution/solid interactions, the traditional geochemical and mineralogical methods have taught everyone a great deal about reactions that take place at mineral surfaces. Whether Earth Scientists are interested in the accumulation of precious elements to form an ore deposit or a hydrocarbon reservoir, or in the wide dispersal of contaminants throughout environmental systems, the chemical processes that control uptake and release of trace components during fluid transport are the same. Data describing bulk solid and solution composition have allowed to make conceptual models of molecular processes and to produce computer models where behaviour in reactive systems can be simulated. However, with traditional techniques alone, it can be difficult to unambiguously select a single model to fit a set of data because several individual processes may be masked by the averaging that is inherent in the macroscopic approach. The traditional bulk analytical methods, such as X-ray diffraction (XRD), Microprobe, Scanning electron microscopy (SEM), Atomic absorption spectroscopy (AAS), potentiometry, chromatography and other wet chemistry methods give information about the identity and structure of minerals and the composition of solutions.

  6. Analytical expression for position sensitivity of linear response beam position monitor having inter-electrode cross talk

    Science.gov (United States)

    Kumar, Mukesh; Ojha, A.; Garg, A. D.; Puntambekar, T. A.; Senecha, V. K.

    2017-02-01

    According to the quasi electrostatic model of linear response capacitive beam position monitor (BPM), the position sensitivity of the device depends only on the aperture of the device and it is independent of processing frequency and load impedance. In practice, however, due to the inter-electrode capacitive coupling (cross talk), the actual position sensitivity of the device decreases with increasing frequency and load impedance. We have taken into account the inter-electrode capacitance to derive and propose a new analytical expression for the position sensitivity as a function of frequency and load impedance. The sensitivity of a linear response shoe-box type BPM has been obtained through simulation using CST Studio Suite to verify and confirm the validity of the new analytical equation. Good agreement between the simulation results and the new analytical expression suggest that this method can be exploited for proper designing of BPM.

  7. Sensitivity analysis of radiative transfer for atmospheric remote sensing in thermal IR: atmospheric weighting functions and surface partials

    Science.gov (United States)

    Ustinov, E. A.

    2003-01-01

    In this presentation, we apply the adjoint sensitivity analysis of radiative transfer in thermal IR to the general case of the analytic evaluation of the weighting functions of atmospheric parameters together with the partial derivatives for the surface parameters. Applications to remote sensing of atmospheres of Mars and Venus are discussed.

  8. Surface modification of polyacrylonitrile fiber for immobilization of antibodies and detection of analyte

    Energy Technology Data Exchange (ETDEWEB)

    Jain, Swati, E-mail: swatijain.iitd@gmail.com [Center for Biomedical Engineering, Indian Institute of Technology, New Delhi, 110016 (India); Chattopadhyay, Sruti, E-mail: srutic@hotmail.com [Center for Biomedical Engineering, Indian Institute of Technology, New Delhi, 110016 (India); Jackeray, Richa, E-mail: richajackeray.iitd@gmail.com [Center for Biomedical Engineering, Indian Institute of Technology, New Delhi, 110016 (India); Singh, Harpal, E-mail: harpal2000@yahoo.com [Center for Biomedical Engineering, Indian Institute of Technology, New Delhi, 110016 (India)

    2009-11-10

    Pendent nitrile groups of multifilamentous polyacrylonitrile (PAN) fibers were reduced to amino groups using lithium aluminum hydride for different time of reduction and amine content was estimated by performing acid-base titrations. Attenuated total reflection-fourier transform infrared spectroscopy (ATR-FTIR) and Differential Scanning Calorimetry (DSC) were used for the characterization of the generated amino groups and thermal properties of the reduced fibers, respectively. The surface morphology of the fibers after reduction and immobilization was characterized using Scanning Electron Microscope (SEM). The newly formed amino groups of the fibers were activated by using glutaraldehyde for the covalent linking of Goat anti-Rabbit IgG-HRP (GAR-HRP) antibody enzyme conjugate. Modified PAN fibers were evaluated as a matrix for sandwich ELISA by using Goat anti-Rabbit antibody (GAR-IgG), Rabbit anti-Goat (RAG-IgG) as analyte and enzyme conjugate GAR-HRP. The fibers reduced for 24 h were able to detect the analyte RAG-IgG at a concentration as low as 3.75 ng mL{sup -1} with 12% skimmed milk as blocking reagent for the optimized concentration of primary antibody GAR-IgG 3 {mu}g mL{sup -1} and peroxidase conjugate GAR-HRP dilution of 8000 fold. The sensitivity, specificity and reproducibility of the developed immunoassay was further established with antibodies present in human blood using Rabbit anti-Human (RAH-IgG) antibody and the corresponding HRP enzyme conjugate. As low as 0.1 {mu}L of human blood was sufficient to perform the assay with the modified fibers.

  9. Transient flow between aquifers and surface water: analytically derived field-scale hydraulic heads and fluxes

    Directory of Open Access Journals (Sweden)

    G. H. de Rooij

    2012-03-01

    Full Text Available The increasing importance of catchment-scale and basin-scale models of the hydrological cycle makes it desirable to have a simple, yet physically realistic model for lateral subsurface water flow. As a first building block towards such a model, analytical solutions are presented for horizontal groundwater flow to surface waters held at prescribed water levels for aquifers with parallel and radial flow. The solutions are valid for a wide array of initial and boundary conditions and additions or withdrawals of water, and can handle discharge into as well as lateral infiltration from the surface water. Expressions for the average hydraulic head, the flux to or from the surface water, and the aquifer-scale hydraulic conductivity are developed to provide output at the scale of the modelled system rather than just point-scale values. The upscaled conductivity is time-variant. It does not depend on the magnitude of the flux but is determined by medium properties as well as the external forcings that drive the flow. For the systems studied, with lateral travel distances not exceeding 10 m, the circular aquifers respond very differently from the infinite-strip aquifers. The modelled fluxes are sensitive to the magnitude of the storage coefficient. For phreatic aquifers a value of 0.2 is argued to be representative, but considerable variations are likely. The effect of varying distributions over the day of recharge damps out rapidly; a soil water model that can provide accurate daily totals is preferable over a less accurate model hat correctly estimates the timing of recharge peaks.

  10. Polymer Inclusion Membranes with Condensed Phase Membrane Introduction Mass Spectrometry (CP-MIMS): Improved Analytical Response Time and Sensitivity.

    Science.gov (United States)

    Vandergrift, Gregory W; Krogh, Erik T; Gill, Chris G

    2017-05-16

    Condensed phase membrane introduction mass spectrometry (CP-MIMS) is an online, in situ analysis technique for low volatility analytes. Analytes diffuse through a hollow fiber membrane, where they are then dissolved by a liquid (condensed) acceptor phase flowing through the membrane lumen. Permeating analytes are entrained to an atmospheric pressure ionization source for subsequent measurement by a mass spectrometer. Larger analytes, with inherently lower diffusivities, suffer from lengthy response times and lower sensitivity, limiting the use of CP-MIMS for their online, real-time measurement. We present the use of a heptane cosolvent in a methanol acceptor phase in combination with a polydimethylsiloxane (PDMS) membrane. The heptane generates an in situ polymer inclusion membrane (PIM) with the PDMS. We report improved measurement response times and greater sensitivity across a suite of analytes studied (gemfibrozil, nonylphenol, triclosan, 2,4,6-trichlorophenol, and naphthenic acids), with detection limits in the low parts per trillion (ppt) range. These improvements are attributed to increasing analyte diffusivities, as well as increased analyte partitioning across the PIM. Response times are ∼3× faster for the larger analytes studied, and calibration sensitivity is improved by up to ∼3.5× using 0.046 mole fraction heptane in the methanol acceptor. We report the use of short sample exposure times and the use of non-steady-state signals to reduce the analytical duty cycle, and illustrate that the use of a PIM provides a simple and robust variant of CP-MIMS amenable to rapid screening of analytes in complex samples.

  11. An efficient analytical decomposition and numerical procedure for boundary layer flow on a continuous stretching surface

    Institute of Scientific and Technical Information of China (English)

    Xuehui Chen; Liancun Zheng; Xinxin Zhang

    2006-01-01

    An efficient Adomian analytical decomposition technique for studying the momentum and heat boundary layer equations with exponentially stretching surface conditions was presented and an approximate analytical solution was obtained, which can be represented in terms of a rapid convergent power series with elegantly computable terms. The reliability and efficiency of the approximate solution were verified using numerical solutions in the literature. The approximate solution can be successfully applied to provide the values of skin friction and the temperature gradient coefficient.

  12. Determination of temperature of moving surface by sensitivity analysis

    CERN Document Server

    Farhanieh, B

    2002-01-01

    In this paper sensitivity analysis in inverse problem solutions is employed to estimate the temperature of a moving surface. Moving finite element method is used for spatial discretization. Time derivatives are approximated using Crank-Nicklson method. The accuracy of the solution is assessed by simulation method. The convergence domain is investigated for the determination of the temperature of a solid fuel.

  13. A Highly Sensitive Gold-Coated Photonic Crystal Fiber Biosensor Based on Surface Plasmon Resonance

    Directory of Open Access Journals (Sweden)

    Md. Rabiul Hasan

    2017-03-01

    Full Text Available In this paper, we numerically demonstrate a two-layer circular lattice photonic crystal fiber (PCF biosensor based on the principle of surface plasmon resonance (SPR. The finite element method (FEM with circular perfectly matched layer (PML boundary condition is applied to evaluate the performance of the proposed sensor. A thin gold layer is deposited outside the PCF structure, which acts as the plasmonic material for this design. The sensing layer (analyte is implemented in the outermost layer, which permits easy and more practical fabrication process compared to analyte is put inside the air holes. It is demonstrated that, at gold layer thickness of 40 nm, the proposed sensor shows maximum sensitivity of 2200 nm/RIU using the wavelength interrogation method in the sensing range between 1.33–1.36. Besides, using an amplitude interrogation method, a maximum sensitivity of 266 RIU−1 and a maximum sensor resolution of 3.75 × 10−5 RIU are obtained. We also discuss how phase matching points are varied with different fiber parameters. Owing to high sensitivity and simple design, the proposed sensor may find important applications in biochemical and biological analyte detection.

  14. Ernst Equation and Riemann Surfaces: Analytical and Numerical Methods

    Energy Technology Data Exchange (ETDEWEB)

    Ernst, Frederick J [FJE Enterprises, 511 County Route 59, Potsdam, NY 13676 (United States)

    2007-06-18

    . Finally, in chapter 8, the difficulties associated with extending the techniques espoused by these authors to other physica lly interesting problems (e.g., when electromagnetic fields are involved) are discussed. In addition to these eight chapters, there are two appendices. The first concerns the theory of Riemann surfaces and the second describes the relationship between the Ernst equation and twistor theory. It should be mentioned that this book may be considered to be an homage to Olaf Richter, whose very promising research life ended prematurely in November 2003. Indeed, a substantial part of the book is based upon his habilitation thesis. It is the reviewer's opinion that the resulting book will be more useful as a resource for those who are already well versed in the subject of integrable systems than as an educational tool for novices who would like to enter this exciting branch of mathematical physics. (book review)

  15. Hafnium dioxide as a dielectric for highly-sensitive waveguide-coupled surface plasmon resonance sensors

    Directory of Open Access Journals (Sweden)

    Kunal Tiwari

    2016-04-01

    Full Text Available Hafnium dioxide has been recognized as an excellent dielectric for microelectronics. However, its usefulness for the surface plasmon based sensors has not yet been tested. Here we investigate its usefulness for waveguide-coupled bi-metallic surface plasmon resonance sensors. Several Ag/HfO2/Au multilayer structure sensors were fabricated and evaluated by optical measurements and computer simulations. The resulting data establish correlations between the growth parameters and sensor performance. The sensor sensitivity to refractive index of analytes is determined to be S n = ∂ θ SPR ∂ n ≥ 4 7 0 . The sensitivity data are supported by simulations, which also predict 314 nm for the evanescent field decay length in air.

  16. 3D Ag/ZnO hybrids for sensitive surface-enhanced Raman scattering detection

    Science.gov (United States)

    Huang, Chenyue; Xu, Chunxiang; Lu, Junfeng; Li, Zhaohui; Tian, Zhengshan

    2016-03-01

    To combine the surface plasma resonance of metal and local field enhancement in metal/semiconductor interface, Ag nanoparticles (NPs) were assembled on a ZnO nanorod array which was grown by hydrothermally on carbon fibers. The construction of dimensional (3D) Surface-Enhanced Raman Scattering (SERS) substrate is used for the sensitive detection of organic pollutants with the advantages such as facile synthesis, short detection time and low cost. The hybrid substrate was manifested a high sensitivity to phenol red at a lower concentration of 1 × 10-9 M and a higher enhancement factor of 3.18 × 109. Moreover, the ZnO nanostructures decorated with Ag NPs were demonstrated self-cleaning function under UV irradiation via photocatalytic degradation of the analytic molecules. The fabrication process of the materials and sensors, optimization of the SERS behaviors for different sized Ag NPs, the mechanism of SERS and recovery were presented with a detailed discussion.

  17. Analytic height correlation function of rough surfaces derived from light scattering

    CERN Document Server

    Zamani, M; Fazeli, S M; Downer, M C; Jafari, G R

    2015-01-01

    We obtain an analytic expression for the height correlation function of a rough surface based on the inverse wave scattering method of Kirchhoff theory. The expression directly relates the height correlation function to diffuse scattered intensity. We test the solution by measuring the angular distribution of light scattered from rough silicon surfaces, solving for the height correlation functions, and comparing them to functions derived from AFM measurements. The results show good agreement. The advantages of this method are its accurate analytical equation for the height correlation function and the simplicity of the experimental setup required to measure it.

  18. Photoactive Fluoropolymer Surfaces that Release Sensitizer Drug Molecules

    Science.gov (United States)

    Ghosh, Goutam; Minnis, Mihaela; Ghogare, Ashwini A.; Abramova, Inna; Cengel, Keith; Busch, Theresa M.; Greer, Alexander

    2015-01-01

    We describe a physical-organic study of two fluoropolymers bearing a photoreleasable PEGylated photosensitizer which generates 1O2(1Δg) [chlorin e6 methoxy tri(ethylene glycol) triester]. The surfaces are Teflon/polyvinylalcohol (PVA) nanocomposite and fluorinated silica. The relative efficiency of these surfaces to photorelease the PEGylated sensitizer [shown previously to be phototoxic to ovarian cancer cells (Kimani, S. et al J. Org. Chem 2012, 77, 10638)] was slightly higher for the nanocomposite. In the presence of red light and O2, 1O2 is formed, which cleaves an ethene linkage to liberate the sensitizer in 68–92% yields. The fluoropolymers were designed to deal with multiple problems. Namely, their success relied not only high O2 solubility and drug repellency, but that the C−F bonds physically quench little 1O2 for its productive use away from the surface. The results obtained here indicate that Teflon-like surfaces have potential uses of delivering sensitizer and singlet oxygen for applications in tissue repair and photodynamic therapy (PDT). PMID:25686407

  19. Photoactive fluoropolymer surfaces that release sensitizer drug molecules.

    Science.gov (United States)

    Ghosh, Goutam; Minnis, Mihaela; Ghogare, Ashwini A; Abramova, Inna; Cengel, Keith A; Busch, Theresa M; Greer, Alexander

    2015-03-12

    We describe a physical-organic study of two fluoropolymers bearing a photoreleasable PEGylated photosensitizer that generates (1)O2((1)Δg) [chlorin e6 methoxy tri(ethylene glycol) triester]. The surfaces are Teflon/poly(vinyl alcohol) (PVA) nanocomposite and fluorinated silica. The relative efficiency of these surfaces to photorelease the PEGylated sensitizer [shown previously to be phototoxic to ovarian cancer cells (Kimani, S. et al. J. Org. Chem 2012, 77, 10638)] was slightly higher for the nanocomposite. In the presence of red light and O2, (1)O2 is formed, which cleaves an ethene linkage to liberate the sensitizer in 68-92% yield. The fluoropolymers were designed to deal with multiple problems. Namely, their success relied not only on high O2 solubility and drug repellency but also on the C-F bonds, which physically quench little (1)O2, for singlet oxygen's productive use away from the surface. The results obtained here indicate that Teflon-like surfaces have potential uses in delivering sensitizer and singlet oxygen for applications in tissue repair and photodynamic therapy (PDT).

  20. Sensitivity Analysis and Optimization of Aerodynamic Configurations with Blend Surfaces

    Science.gov (United States)

    Thomas, A. M.; Tiwari, S. N.

    1997-01-01

    A novel (geometrical) parametrization procedure using solutions to a suitably chosen fourth order partial differential equation is used to define a class of airplane configurations. Inclusive in this definition are surface grids, volume grids, and grid sensitivity. The general airplane configuration has wing, fuselage, vertical tail and horizontal tail. The design variables are incorporated into the boundary conditions, and the solution is expressed as a Fourier series. The fuselage has circular cross section, and the radius is an algebraic function of four design parameters and an independent computational variable. Volume grids are obtained through an application of the Control Point Form method. A graphic interface software is developed which dynamically changes the surface of the airplane configuration with the change in input design variable. The software is made user friendly and is targeted towards the initial conceptual development of any aerodynamic configurations. Grid sensitivity with respect to surface design parameters and aerodynamic sensitivity coefficients based on potential flow is obtained using an Automatic Differentiation precompiler software tool ADIFOR. Aerodynamic shape optimization of the complete aircraft with twenty four design variables is performed. Unstructured and structured volume grids and Euler solutions are obtained with standard software to demonstrate the feasibility of the new surface definition.

  1. Optical cavity coupled surface plasmon resonance sensing for enhanced sensitivity

    Institute of Scientific and Technical Information of China (English)

    Zheng Zheng; Xin Zhao; Jinsong Zhu; Jim Diamond

    2008-01-01

    A surface plasmon resonance (SPR) sensing system based on the optical cavity enhanced detection tech-nique is experimentally demonstrated. A fiber-optic laser cavity is built with a SPR sensor inside. By measuring the laser output power when the cavity is biased near the threshold point, the sensitivity, defined as the dependence of the output optical intensity on the sample variations, can be increased by about one order of magnitude compared to that of the SPR sensor alone under the intensity interrogation scheme. This could facilitate ultra-high sensitivity SPR biosensing applications. Further system miniaturization is possible by using integrated optical components and waveguide SPR sensors.

  2. Surface Binding and Organization of Sensitizing Dyes on Metal Oxide Single Crystal Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Parkinson, Bruce

    2010-06-04

    Even though investigations of dye-sensitized nanocrystalline semiconductors in solar cells has dominated research on dye-sensitized semiconductors over the past two decades. Single crystal electrodes represent far simpler model systems for studying the sensitization process with a continuing train of studies dating back more than forty years. Even today single crystal surfaces prove to be more controlled experimental models for the study of dye-sensitized semiconductors than the nanocrystalline substrates. We analyzed the scientific advances in the model sensitized single crystal systems that preceded the introduction of nanocrystalline semiconductor electrodes. It then follows the single crystal research to the present, illustrating both their striking simplicity of use and clarity of interpretation relative to nanocrystalline electrodes. Researchers have employed many electrochemical, photochemical and scanning probe techniques for studying monolayer quantities of sensitizing dyes at specific crystallographic faces of different semiconductors. These methods include photochronocoulometry, electronic spectroscopy and flash photolysis of dyes at potential-controlled semiconductor electrodes and the use of total internal reflection methods. In addition, we describe the preparation of surfaces of single crystal SnS2 and TiO2 electrodes to serve as reproducible model systems for charge separation at dye sensitized solar cells. This process involves cleaving the SnS2 electrodes and a photoelectrochemical surface treatment for TiO2 that produces clean surfaces for sensitization (as verified by AFM) resulting in near unity yields for electron transfer from the molecular excited dyes into the conduction band.

  3. Surface Sensitive Techniques for Advanced Characterization of Luminescent Materials.

    Science.gov (United States)

    Swart, Hendrik C

    2017-08-04

    The important role of surface sensitive characterization techniques such as Auger electron spectroscopy (AES), X-ray photo electron spectroscopy (XPS), time of flight scanning ion mass spectrometry (TOF-SIMS) and High resolution transmission electron microscopy (HRTEM) for the characterization of different phosphor materials is discussed in this short review by giving selective examples from previous obtained results. AES is used to monitor surface reactions during electron bombardment and also to determine the elemental composition of the surfaces of the materials, while XPS and TOF-SIMS are used for determining the surface chemical composition and valence state of the dopants. The role of XPS to determine the presence of defects in the phosphor matrix is also stated with the different examples. The role of HRTEM in combination with Energy dispersive spectroscopy (EDS) for nanoparticle characterization is also pointed out.

  4. Phonon dispersion on Ag (100) surface: A modified analytic embedded atom method study

    Science.gov (United States)

    Xiao-Jun, Zhang; Chang-Le, Chen

    2016-01-01

    Within the harmonic approximation, the analytic expression of the dynamical matrix is derived based on the modified analytic embedded atom method (MAEAM) and the dynamics theory of surface lattice. The surface phonon dispersions along three major symmetry directions , and X¯M¯ are calculated for the clean Ag (100) surface by using our derived formulas. We then discuss the polarization and localization of surface modes at points X¯ and M¯ by plotting the squared polarization vectors as a function of the layer index. The phonon frequencies of the surface modes calculated by MAEAM are compared with the available experimental and other theoretical data. It is found that the present results are generally in agreement with the referenced experimental or theoretical results, with a maximum deviation of 10.4%. The agreement shows that the modified analytic embedded atom method is a reasonable many-body potential model to quickly describe the surface lattice vibration. It also lays a significant foundation for studying the surface lattice vibration in other metals. Project supported by the National Natural Science Foundation of China (Grant Nos. 61471301 and 61078057), the Scientific Research Program Funded by Shaanxi Provincial Education Department, China (Grant No. 14JK1301), and the Specialized Research Fund for the Doctoral Program of Higher Education, China (Grant No. 20126102110045).

  5. High-sensitivity cardiac troponin assays: From improved analytical performance to enhanced risk stratification.

    Science.gov (United States)

    Kozinski, Marek; Krintus, Magdalena; Kubica, Jacek; Sypniewska, Grazyna

    2017-05-01

    Implementation of cardiac troponin (cTn) assays has revolutionized the diagnosis, risk stratification, triage and management of patients with suspected myocardial infarction (MI). The Universal Definition of MI brought about a shift in the diagnostics of MI, from an approach primarily based on electrocardiography (ECG) to one primarily based on biomarkers. Currently, detection of a rise and/or fall in concentration or activity of myocardial necrosis biomarkers, preferentially cTns, with at least one value above the 99th percentile upper reference limit (URL), is the essential component for the diagnosis of MI. High-sensitivity cardiac troponin (hs-cTn) assays with their superior analytical performance were designed to further facilitate clinical decision making. The ability of hs-cTn assays to detect measurable cTn concentrations in at least 50% of healthy individuals, along with their improved precision (expressed as coefficient of variation ≤10% at the 99th percentile URL) associated with increased recognition of changing values, leads to enhanced risk stratification of patients with suspected MI, and also enables them to be used as prognostic tools potentially useful in other patient subsets. In this comprehensive review, we aim to integrate updated laboratory and clinical knowledge regarding hs-cTn assays in order to promote their optimal use in daily practice. We primarily focus on the role of hs-cTn assays in patients with suspected MI, discussing recommended diagnostic algorithms and result interpretation. Emphasis is also placed on the release of cTns following myocardial injury, the characteristics of antibodies used in available cTn immunoassays, and analytical performance of hs-cTn assays. In this paper, we also review potential challenges related to the selection of a healthy reference population in determining 99th percentile values, biological variation of hs-cTns, inequality between hs-cTn assays, and outline the current status of c

  6. Analytical Study on Impingement Heat Transfer with Single—Phase Free—Surface Circular Liquid Jets

    Institute of Scientific and Technical Information of China (English)

    C.F.Ma; T.Masuoka; 等

    1996-01-01

    An analytical research was conducted to study heat transfer from horizontal surfaces to normally impinging circular jets under arbitrary-heat-flux conditions.The laminar thermal and hydraulic bound ary layers were divided into five regions of flow.General expressions of heat transfer coefficients were obtained in all the four regions of stagnation and wall jet zones before the hydraulic jump.

  7. Quantifying Measurement Fluctuations from Stochastic Surface Processes on Sensors with Heterogeneous Sensitivity

    Science.gov (United States)

    Charmet, Jérôme; Michaels, Thomas C. T.; Daly, Ronan; Prasad, Abhinav; Thiruvenkathanathan, Pradyumna; Langley, Robin S.; Knowles, Tuomas P. J.; Seshia, Ashwin A.

    2016-06-01

    Recent advances in micro- and nanotechnology have enabled the development of ultrasensitive sensors capable of detecting small numbers of species. In general, however, the response induced by the random adsorption of a small number of objects onto the surface of such sensors results in significant fluctuations due to the heterogeneous sensitivity inherent to many such sensors coupled to statistical fluctuations in the particle number. At present, this issue is addressed by considering either the limit of very large numbers of analytes, where fluctuations vanish, or the converse limit, where the sensor response is governed by individual analytes. Many cases of practical interest, however, fall between these two limits and remain challenging to analyze. Here, we address this limitation by deriving a general theoretical framework for quantifying measurement variations on mechanical resonators resulting from statistical-number fluctuations of analyte species. Our results provide insights into the stochastic processes in the sensing environment and offer opportunities to improve the performance of mechanical-resonator-based sensors. This metric can be used, among others, to aid in the design of robust sensor platforms to reach ultrahigh-resolution measurements using an array of sensors. These concepts, illustrated here in the context of biosensing, are general and can therefore be adapted and extended to other sensors with heterogeneous sensitivity.

  8. Sensitivity of metal nanoparticle surface plasmon resonance to the dielectric environment.

    Science.gov (United States)

    Miller, Molly M; Lazarides, Anne A

    2005-11-24

    Electrodynamic simulations of gold nanoparticle spectra were used to investigate the sensitivity of localized surface plasmon band position to the refractive index, n, of the medium for nanoparticles of various shapes and nanoshells of various structures. Among single-component nanoparticles less than 130 nm in size, sensitivities of dipole resonance positions to bulk refractive index are found to depend only upon the wavelength of the resonance and the dielectric properties of the metal and the medium. Among particle plasmons that peak in the frequency range where the real part of the metal dielectric function varies linearly with wavelength and the imaginary part is small and slowly varying, the sensitivity of the peak wavelength, lambda, to refractive index, n, is found to be a linearly increasing function of lambda, regardless of the structural features of the particle that determine lambda. Quasistatic theory is used to derive an analytical expression for the refractive index sensitivity of small particle plasmon peaks. Through this analysis, the dependence of sensitivity on band position is found to be determined by the wavelength dependence of the real part, epsilon', of the particle dielectric function, and the sensitivity results are found to extend to all particles with resonance conditions of the form, epsilon' = -2chin(2), where chi is a function of geometric parameters and other constants. The sensitivity results observed using accurate computational methods for dipolar plasmon bands of gold nanodisks, nanorods, and hollow nanoshells extend, therefore, to particles of other shapes (such as hexagonal and chopped tetrahedral), composed of other metals, and to higher-order modes. The bulk refractive index sensitivity yielded by the theory serves as an upper bound to sensitivities of nanoparticles on dielectric substrates and sensitivities of nanoparticles to local refractive index changes, such as those associated with biomolecule sensing.

  9. Phase-sensitive surface plasmon resonance biosensors: methodology, instrumentation and applications

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Y.H. [Department of Electronic Engineering, The Chinese University of Hong Kong, Shatin, NT (China); Center for Environmental Sensing and Modeling, Singapore-MIT Alliance for Research and Technology (Singapore); Ho, H.P. [Department of Electronic Engineering, The Chinese University of Hong Kong, Shatin, NT (China); Kong, S.K. [Programme of Biochemistry, School of Life Sciences, The Chinese University of Hong Kong, Shatin, NT (China); Kabashin, A.V. [Laboratoire Lasers, Plasmas et Procedes Photoniques (LP3, UMR 7341 CNRS), Faculte des Sciences de Luminy, Aix-Marseille University, 163 Avenue de Luminy, C. P. 917, 13288 Marseille Cedex 09 (France)

    2012-11-15

    Surface Plasmon Resonance (SPR) has become a central tool for label-free characterization of biomolecular interactions. Based on monitoring of amplitude characteristics, conventional SPR sensors have been extensively explored, commercialized and applied for studies of many important interactions (antigen-antibody, protein-ligand etc), but this technology still lacks of sensitivity for the detection of relatively small and low copy number compounds. Phase-sensitive SPR has recently emerged as an upgrade of this technology to resolve the sensitivity issue. Profiting from a sharp phase jump under SPR and ultra-sensitive tools of its control, this technology offers up to 100-time improvement of the detection limit, giving access to the detection of trace amounts of small molecular weight analytes (drugs etc). This paper intends to provide a tutorial on basic concepts of phase detection in SPR sensing, compare the performance of phase- and amplitude-sensitive sensors, review recent progress in the development and applications of phase-sensitive SPR sensors, and outline future prospects and trends of this technology. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  10. Semi-automated De-identification of German Content Sensitive Reports for Big Data Analytics.

    Science.gov (United States)

    Seuss, Hannes; Dankerl, Peter; Ihle, Matthias; Grandjean, Andrea; Hammon, Rebecca; Kaestle, Nicola; Fasching, Peter A; Maier, Christian; Christoph, Jan; Sedlmayr, Martin; Uder, Michael; Cavallaro, Alexander; Hammon, Matthias

    2017-07-01

    reports enables reliable detection and labeling of sensitive data in different types of medical reports. Key Points:  · Collaborations between different institutions require de-identification of patients' data. · Software-based de-identification of content-sensitive reports grows in importance as a result of 'Big data'. · A de-identification software was developed and tested natively and after training. · The proposed de-identification software worked quite reliably, following training with roughly 100 edited reports. · A final check of the texts by an authorized person remains necessary. Citation Format · Seuss H, Dankerl P, Ihle M et al. Semi-automated De-identification of German Content Sensitive Reports for Big Data Analytics. Fortschr Röntgenstr 2017; 189: 661 - 671. © Georg Thieme Verlag KG Stuttgart · New York.

  11. Detailed analytical approach to the Gaussian surface bidirectional reflectance distribution function specular component applied to the sea surface.

    Science.gov (United States)

    Ross, Vincent; Dion, Denis; Potvin, Guy

    2005-11-01

    A statistical sea surface specular BRDF (bidirectional reflectance distribution function) model is developed that includes mutual shadowing by waves, wave facet hiding, and projection weighting. The integral form of the model is reduced to an analytical form by making minor and justifiable approximations. The new form of the BRDF thus allows one to compute sea reflected radiance more than 100 times faster than the traditional numerical solutions. The repercussions of the approximations used in the model are discussed. Using the analytical form of the BRDF, an analytical approximation is also obtained for the reflected sun radiance that is always good to within 1% of the numerical solution for sun elevations of more than 10 degrees above the horizon. The model is validated against measured sea radiances found in the literature and is shown to be in very good agreement.

  12. Shallow groundwater thermal sensitivity to climate change and land cover disturbances: derivation of analytical expressions and implications for stream temperature projections

    Directory of Open Access Journals (Sweden)

    B. L. Kurylyk

    2014-11-01

    Full Text Available Climate change is expected to increase stream temperatures, and the projected warming may alter the spatial extent of habitat for coldwater fish and other aquatic taxa. Recent studies have proposed that stream thermal sensitivities, derived from short term air temperature variations, can be employed to infer future stream warming due to long term climate change. However, this approach does not consider the potential for streambed heat fluxes to increase due to gradual warming of shallow groundwater. The temperature of shallow groundwater is particularly important for the thermal regimes of groundwater-dominated streams and rivers. Also, other recent stream temperature studies have investigated how land surface perturbations, such as wildfires or timber harvesting, can influence stream temperatures by changing surface heat fluxes, but these studies have typically not considered how these surface disturbances can also alter shallow groundwater temperatures and consequent streambed heat fluxes. In this study, several analytical solutions to the one-dimensional unsteady advection–diffusion equation for subsurface heat transport are employed to investigate the timing and magnitude of groundwater warming due to seasonal and long term variability in land surface temperatures. Novel groundwater thermal sensitivity formulae are proposed that accommodate different surface warming scenarios. The thermal sensitivity formulae demonstrate that shallow groundwater will warm in response to climate change and other surface perturbations, but the timing and magnitude of the warming depends on the rate of surface warming, subsurface thermal properties, aquifer depth, and groundwater velocity. The results also emphasize the difference between the thermal sensitivity of shallow groundwater to short term (e.g. seasonal and long term (e.g. multi-decadal land surface temperature variability, and thus demonstrate the limitations of using short term air and water

  13. Semi-analytical analysis of the response of the air temperature over the land surface to the global vegetation distribution

    Institute of Scientific and Technical Information of China (English)

    LIU Fei; CHAO JiPing

    2009-01-01

    Response of the air temperature over the land surface to the global vegetation distribution is investigated, using a three-dimensional governing equation to simulate the steady, large-scale, limited amplitude perturbation of the free, inviscid and adiabatic atmosphere. The adoption of the static equation leads to a temperature governing equation in the terrain following coordinate. With the prescribed temperature as the upper boundary condition and the radiation balance as the lower boundary condition, the semi-analytical solution of the global circulation temperature can be calculated. In this article, only the air temperature (at 2 m height) over the land surface is analyzed, and the result suggests that this model can simulate the air temperature pattern over the land surface reasonably. A better simulation occurs when a simple feedback of the albedo on the temperature is included. Two sensitivity experiments are analyzed through this model. One suggests that the air temperature over the land surface descends obviously when the land surface is covered with ice all over, while another suggests that the air temperature rises a little when the land surface is covered with forest except the ice-covered area. This model appears to be a good tool to study the response of the air temperature to the vegetation distribution. Limitations of the model are also discussed.

  14. Highly sensitive BTX detection using surface functionalized QCM sensor

    Energy Technology Data Exchange (ETDEWEB)

    Bozkurt, Asuman Aşıkoğlu; Özdemir, Okan; Altındal, Ahmet, E-mail: altindal@yildiz.edu.tr [Department of Physics, Yildiz Technical University, Davutpasa, 34210 Istanbul (Turkey)

    2016-03-25

    A novel organic compound was designed and successfully synthesized for the fabrication of QCM based sensors to detect the low concentrations of BTX gases in indoor air. The effect of the long-range electron orbital delocalization on the BTX vapour sensing properties of azo-bridged Pcs based chemiresistor-type sensors have also been investigated in this work. The sensing behaviour of the film for the online detection of volatile organic solvent vapors was investigated by utilizing an AT-cut quartz crystal resonator. It was observed that the adsorption of the target molecules on the coating surface cause a reversible negative frequency shift of the resonator. Thus, a variety of solvent vapors can be detected by using the phthalocyanine film as sensitive coating, with sensitivity in the ppm range and response times in the order of several seconds depending on the molecular structure of the organic solvent.

  15. SENSITIVITY OF IMPRESSION CYTOLOGY IN DIAGNOSING OCULAR SURFACE SQUAMOUS NEOPLASIA

    Directory of Open Access Journals (Sweden)

    Malleswari

    2015-10-01

    Full Text Available OSSN describes a spectrum of neoplastic lesions, originating from squamous epithelium ranging from simple dysplasia to invasive squamous cell carcinoma (SCC, involving the conjunctiva, limbus and the cornea. Impression cytology refers to the technique by which superficial layers of the ocular surface are removed through application of cellulose acetate filter material onto the ocular surface AIM: To Assess the Sensitivity of Impression Cytology in the Diagnosis of Ocular Surface Squamous Neoplasia Using Millipore Filter Paper. MATERIALS AND METHODS: This is a Prospective Observational and Interventional Study conducted at Sarojini Devi Eye Hospital and Gandhi Medical College/Hospital, Hyderabad. Study was conducted from July2013 to Feb2015 and included 50patients presenting with conjunctival mass at the limbus or on the conjunctiva Hospital ethics committee approval was obtained No financials involved in the study. RESULTS: A total of 50Excision biopsies of 50patients suspected for OSSN were performed there were 40 males and 10females Excision biopsy confirmed the Impression Cytology results in 44 cases. In 6 cases there was poor correlation among which 4cases showed mild dysplasia in Impression Cytology while HPE showed Invasive Squamous cell carcinoma in 2cases few dysplastic cells were noted in Impression cytology but HPE showed Carcinoma in situ. CONCLUSION: This study shows that Impression Cytology has a promising role in diagnosing Ocular Surface Squamous Neoplasia for its high positive predictive accuracy (95.65% compared with tissue histology.

  16. Surface acoustic wave based analytical system for the detection of liquid detergents

    OpenAIRE

    2012-01-01

    A novel analytical sensing system has been designed for the characterization and discrimination of different detergents in water. This micro-sensor system could play a key role in the development of more efficient and environmentally-friendly washing machines by enabling the measurement of residual detergents. The sensing system comprises a dual shear-horizontal surface acoustic wave (SH-SAW) resonator sensor housed within a poly-dimethylsiloxane (PDMS) microfluidic chamber. Free and electric...

  17. An analytical stability theory for Faraday waves and the observation of the harmonic surface response

    CERN Document Server

    Müller, H W; Wagner, C; Albers, J; Knorr, K

    1996-01-01

    We present an analytical stability theory for the onset of the Faraday instability, applying over a wide frequency range between shallow water gravity and deep water capillary waves. For sufficiently thin fluid layers the surface is predicted to occur in harmonic rather than subharmonic resonance with the forcing. An experimental confirmation of this result is given. PACS: 47.20.Ma, 47.20.Gv, 47.15.Cb

  18. Sensitivity of surface meteorological analyses to observation networks

    Science.gov (United States)

    Tyndall, Daniel Paul

    A computationally efficient variational analysis system for two-dimensional meteorological fields is developed and described. This analysis approach is most efficient when the number of analysis grid points is much larger than the number of available observations, such as for large domain mesoscale analyses. The analysis system is developed using MATLAB software and can take advantage of multiple processors or processor cores. A version of the analysis system has been exported as a platform independent application (i.e., can be run on Windows, Linux, or Macintosh OS X desktop computers without a MATLAB license) with input/output operations handled by commonly available internet software combined with data archives at the University of Utah. The impact of observation networks on the meteorological analyses is assessed by utilizing a percentile ranking of individual observation sensitivity and impact, which is computed by using the adjoint of the variational surface assimilation system. This methodology is demonstrated using a case study of the analysis from 1400 UTC 27 October 2010 over the entire contiguous United States domain. The sensitivity of this approach to the dependence of the background error covariance on observation density is examined. Observation sensitivity and impact provide insight on the influence of observations from heterogeneous observing networks as well as serve as objective metrics for quality control procedures that may help to identify stations with significant siting, reporting, or representativeness issues.

  19. 3D Ag/ZnO hybrids for sensitive surface-enhanced Raman scattering detection

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Chenyue, E-mail: 493958623@qq.com; Xu, Chunxiang, E-mail: xcxseu@seu.edu.cn; Lu, Junfeng, E-mail: ljf870813@126.com; Li, Zhaohui, E-mail: zhhuilee@sohu.com; Tian, Zhengshan, E-mail: tianzhengshan@163.com

    2016-03-01

    Graphical abstract: - Highlights: • Ag/ZnO hybrids are fabricated and optimized as SERS substrates. • The enhancement contribution of each component in the substrates is discussed. • The substrates have high reproducibility and sensitivity. • The substrates show good photocatalytic activity. - Abstract: To combine the surface plasma resonance of metal and local field enhancement in metal/semiconductor interface, Ag nanoparticles (NPs) were assembled on a ZnO nanorod array which was grown by hydrothermally on carbon fibers. The construction of dimensional (3D) Surface-Enhanced Raman Scattering (SERS) substrate is used for the sensitive detection of organic pollutants with the advantages such as facile synthesis, short detection time and low cost. The hybrid substrate was manifested a high sensitivity to phenol red at a lower concentration of 1 × 10{sup –9} M and a higher enhancement factor of 3.18 × 10{sup 9}. Moreover, the ZnO nanostructures decorated with Ag NPs were demonstrated self-cleaning function under UV irradiation via photocatalytic degradation of the analytic molecules. The fabrication process of the materials and sensors, optimization of the SERS behaviors for different sized Ag NPs, the mechanism of SERS and recovery were presented with a detailed discussion.

  20. Nanometal particle reagents for sensitive, MEMS based fiber-optic, multi-analyte, immuno-biosensing

    Science.gov (United States)

    Hong, Bin

    Integration of nanotechnology to medical diagnostics has brought a new era to public health practice. An excellent example is the utilization of unique optoelectronic properties of nanoparticles to develop highly sensitive biosensing devices for point-of-care (POC) disease diagnosis/prognosis. Fluorophore mediated, immuno-biosensors are important disease detection tools. The property of intra-molecular fluorescence quenching of most fluorophores, however, limits the sensitivity of this type of sensors. A plasmon-rich nanometal particle (NMP) can transfer the lone pair electrons of a fluorophore, which normally participate in the fluorescence self-quenching, to its surface plasmon field, resulting in artificial fluorescence enhancement. The enhancement was found to depend on the metal type, the particle size, the distance between a particle and a fluorophore, and the quantum yield of a fluorophore. Some biocompatible solvents were also found to increase the fluorescence emission efficiency via effective dipole coupling between the fluorophore and the solvent molecule. The application of solvents in inmuno-sensing could additionally improve the fluorescence light retrieval by the conformational change of the protein complexes in solvent. The mixture of the NMP and the solvent, which we defined as nanometal particle reagent (NMPR), provided even higher enhancements. Cardiovascular diseases (CVDs) kill 1 person in every 6 seconds. Among the CVDs, acute myocardial infarction (AMI; commonly known as heart attack) is the most dangerous and time-sensitive killer. A rapid and accurate AMI diagnosis is crucial for saving many lives. For this purpose, a fluorophore mediated, immuno-reaction based, multi-cardiac-marker sensing device was developed, to quantify four myocardium-specific proteins simultaneously, accurately, rapidly, and user-friendly. The four cardiac markers of our choice were myoglobin (MG), C-reactive protein (CRP), cardiac troponin I (cTnI), and B

  1. Surface plasmon resonator using high sensitive resonance telecommunication wavelengths for DNA sensors of Mycobacterium tuberculosis with thiol-modified probes.

    Science.gov (United States)

    Hsu, Shih-Hsiang; Hung, Shao-Chiang; Chen, Yu-Kun; Jian, Zhi-Hao

    2014-12-25

    Various analytes can be verified by surface plasmon resonance, thus continuous improvement of this sensing technology is crucial for better sensing selection and higher sensitivity. The SPR sensitivity on the wavelength modulation is enhanced with increasing wavelengths. The telecommunication wavelength range was then utilized to detect Mycobacterium tuberculosis (MTB) deoxyribonucleic acid (DNA) under two situations, without immobilization and with 5'-thiol end labeled IS6100 DNA probes, for SPR sensitivity comparison. The experimental data demonstrated that the SPR sensitivity increased more than 13 times with the wavelength modulation after immobilization. Since the operating wavelength accuracy of a tunable laser source can be controlled within 0.001 nm, the sensitivity and resolution on immobilized MTB DNA were determined as 1.04 nm/(μg/mL) and 0.9 ng/mL, respectively.

  2. Protein adhesion on dental surfaces-a combined surface analytical approach.

    Science.gov (United States)

    Müller, Christine; Wald, Johanna; Hoth-Hannig, Wiebke; Umanskaya, Natalia; Scholz, Daniel; Hannig, Matthias; Ziegler, Christiane

    2011-05-01

    Protein adsorption is a field of huge interest in a number of application fields. Information on protein adhesion is accessible by a variety of methods. However, the results obtained are significantly influenced by the applied technique. The objective of this work was to understand the role of adhesion forces (obtained by scanning force spectroscopy, SFS) in the process of protein adsorption and desorption. In SFS, the protein is forced to and retracted from the surface, even under unfavorable conditions, in contrast to the natural situation. Furthermore, adhesion forces are correlated with adhesion energies, neglecting the entropic part in the Gibbs enthalpy. In this context, dynamic contact angle (DCA) measurements were performed to identify the potential of this method to complement SFS data. In DCA measurements, the protein diffuses voluntarily to the surface and information on surface coverage and reversibility of adsorption is obtained, including entropic effects (conformational changes and hydrophobic effect). It could be shown that the surface coverage (by DCA) of bovine serum albumin on dental materials correlates well with the adhesion forces (by SFS) if no hydrophobic surface is involved. On those, the entropic hydrophobic effect plays a major role. As a second task, the reversibility of the protein adsorption, i.e., the voluntary desorption as studied by DCA, was compared to the adhesion forces. Here, a correlation between low adhesion forces and good reversibility could be found as long as no covalent bonds were involved. The comparative study of DCA and SFS, thus, leads to a more detailed picture of the complete adsorption/desorption cycle.

  3. Sensitive carbohydrate detection using surface enhanced Raman tagging.

    Science.gov (United States)

    Vangala, Karthikeshwar; Yanney, Michael; Hsiao, Cheng-Te; Wu, Wells W; Shen, Rong-Fong; Zou, Sige; Sygula, Andrzej; Zhang, Dongmao

    2010-12-15

    Glycomic analysis is an increasingly important field in biological and biomedical research as glycosylation is one of the most important protein post-translational modifications. We have developed a new technique to detect carbohydrates using surface enhanced Raman spectroscopy (SERS) by designing and applying a Rhodamine B derivative as the SERS tag. Using a reductive amination reaction, the Rhodamine-based tag (RT) was successfully conjugated to three model carbohydrates (glucose, lactose, and glucuronic acid). SERS detection limits obtained with a 633 nm HeNe laser were ∼1 nM in concentration for all the RT-carbohydrate conjugates and ∼10 fmol in total sample consumption. The dynamic range of the SERS method is about 4 orders of magnitude, spanning from 1 nM to 5 μM. Ratiometric SERS quantification using isotope-substituted SERS internal references allows comparative quantifications of carbohydrates labeled with RT and deuterium/hydrogen substituted RT tags, respectively. In addition to enhancing the SERS detection of the tagged carbohydrates, the Rhodamine tagging facilitates fluorescence and mass spectrometric detection of carbohydrates. Current fluorescence sensitivity of RT-carbohydrates is ∼3 nM in concentration while the mass spectrometry (MS) sensitivity is about 1 fmol, achieved with a linear ion trap electrospray ionization (ESI)-MS instrument. Potential applications that take advantage of the high SERS, fluorescence, and MS sensitivity of this SERS tagging strategy are discussed for practical glycomic analysis where carbohydrates may be quantified with a fluorescence and SERS technique and then identified with ESI-MS techniques.

  4. Analytical investigation of the one dimensional heat transfer in logarithmic various surfaces

    Directory of Open Access Journals (Sweden)

    A. Vahabzadeh

    2016-03-01

    Full Text Available The purpose of the present study was to investigate of the effect of temperature variation on the logarithmic surface. By using the appropriate similarity transformation for the generation components and temperature, the basic equations governing flow and heat transfer are reduced to a set of ordinary differential equations. These equations have been solved approximately subject to the relevant boundary conditions with numerical and analytical techniques. The reliability and performance of the present method have been compared with the numerical method (Runge–Kutta fourth-rate to solve this problem. Then, LSM is used to solve nonlinear equation in heat transfer. This method is useful and practical for solving the nonlinear equation in heat transfer. It is observed that the obtained results by present analytical method are very close to result of the numerical method. Furthermore, the results show that the temperature profiles decreased by increasing the α number, and, temperature profiles increased by increasing the β number.

  5. An analytical formalism accounting for clouds and other "surfaces" for exoplanet transmission spectroscopy

    CERN Document Server

    Bétrémieux, Yan

    2016-01-01

    Although the formalism of Lecavelier des Etangs et al. (2008) is extremely useful to understand what shapes transmission spectra of exoplanets, it does not include the effects of a sharp change in flux with altitude generally associated with surfaces and optically thick clouds. Recent advances in understanding the effects of refraction in exoplanet transmission spectra have, however, demonstrated that even clear thick atmospheres have such a sharp change in flux due to a refractive boundary. We derive a more widely applicable analytical formalism by including first-order effects from all these "surfaces" to compute an exoplanet's effective radius, effective atmospheric thickness, and spectral modulation for an atmosphere with a constant scale height. We show that the effective radius cannot be located below these "surfaces" and that our formalism matches Lecavelier des Etangs et al. (2008)'s in the case of a clear atmosphere. Our formalism explains why clouds and refraction reduce the contrast of spectral fea...

  6. Characterization of Floating Surface Layers of Lipids and Lipopolymers by Surface-Sensitive Scattering

    Science.gov (United States)

    Krüger, Peter; Lösche, Mathias

    Nanotechnology and molecular (bio-)engineering are making ever deepening inroads into everybodys daily life. Physicochemical and biotechnological achievements in the design of physiologically active supramolecular assemblies have brought about the quest for their submolecular-level characterization. We employ surface-sensitive scattering techniques for the investigation of planar lipid membranes - floating monolayers on aqueous surfaces - to correlate structural, functional and dynamic aspects of biomembrane models. This chapter surveys recent work on the submolecular structure of floating phospholipid monolayers - where the advent of third-generation synchrotron X-ray sources has driven the development of realistic, submolecular-scale quasi-chemical models - as well as of more complex systems: cation binding to anionic lipid surfaces; conformational changes of lipopolymers undergoing phase transitions; the conformational organization of phosphatidylinositol and phosphatidylinositides, as examples of physiologically important lipids; and the adsorption of peptides (neuropeptide Y, NPY) or solvents (dimethylsulfoxide, DMSO) onto phospholipid surface layers.

  7. Loading of red blood cells with an analyte-sensitive dye for development of a long-term monitoring technique

    Science.gov (United States)

    Ritter, Sarah C.; Meissner, Kenith E.

    2012-03-01

    Measurement of blood analytes, such as pH and glucose, provide crucial information about a patient's health. Some such analytes, such as glucose in the case of diabetes, require long-term or near-continuous monitoring for proper disease management. However, current monitoring techniques are far from ideal: multiple-per-day finger stick tests are inconvenient and painful for the patient; implantable sensors have short functional life spans (i.e., 3-7 days). Red blood cells serve as an attractive alternative for carriers of analyte sensors. Once reintroduced to the blood stream, these carriers may continue to live for the remainder of their life span (120 days for humans). They are also biodegradable and biocompatible, thereby eliminating the immune system response common for many implanted devices. The proposed carrier system takes advantage of the ability of the red blood cells to swell in response to a decrease in the osmolarity of the extracellular solution. Just before the membranes lyse, they develop small pores on the scale of tens of nanometers. Analyte-sensitive dyes in the extracellular solution may then diffuse into the perforated red blood cells and become entrapped upon restoration of physiological temperature and osmolarity. Because the membranes contain various analyte transporters, intracellular analyte levels rapidly equilibrate to those of the extracellular solution. A fluorescent dye has been loaded inside of red blood cells using a preswelling technique. Alterations in preparation parameters have been shown to affect characteristics of the resulting dye-loaded red blood cells (e.g., intensity of fluorescence).

  8. A surface analytical examination of Stringer particles in Al-Li-Cu alloys

    Science.gov (United States)

    Larson, L. A.; Avalos-Borja, M.; Pizzo, P. P.

    1983-01-01

    A surface analytical examination of powder metallurgy processed Al-Li-Cu alloys was conducted. The oxide stringer particles often found in these alloys was characterized. Particle characterization is important to more fully understand their impact on the stress corrosion and fracture properties of the alloy. The techniques used were SIMS (Secondary Ion Mass Spectroscopy) and SAM (Scanning Auger Microscopy). The results indicate that the oxide stringer particles contain both Al and Li with relatively high Li content and the Li compounds may be associated with the stringer particles, thereby locally depleting the adjacent matrix of Li solute.

  9. Analytical modelling of modular and unequal tooth width surface-mounted permanent magnet machines

    OpenAIRE

    Li, G. J.; Zhu, Z-Q.

    2015-01-01

    This paper presents simple analytical modelling for 2 types of 3-phase surface-mounted permanent magnet (SPM) machines such as modular and unequal tooth width (UNET) machines with different slot/pole number combinations. It is based on the slotless open-circuit air-gap flux density and the slotted air-gap relative permeance calculations. This model allows calculating the open-circuit air-gap flux density, phase flux linkage and back electromotive force (EMF), average torque of both the modula...

  10. Analytic solution for fluxons in a long Josephson junction with surface losses

    DEFF Research Database (Denmark)

    Sakai, S.; Pedersen, Niels Falsig

    1986-01-01

    Analytic solutions for a fluxon in a long Josephson junction in the presence of surface losses (β term) as well as shunt losses (α term) are obtained by assuming a triangular current-phase relation. This theoretical result provides exact information on fluxon properties (e.g., the line shape, vel......, velocity, etc.), independent of the magnitude of α and β. We find that if β is smaller than a critical value, the fluxon behavior is similar to that of the β=0 case, but if β is larger, quite different behavior is observed, particularly in the high-velocity region....

  11. Analytical modeling and thermodynamic analysis of robust superhydrophobic surfaces with inverse-trapezoidal microstructures.

    Science.gov (United States)

    Im, Maesoon; Im, Hwon; Lee, Joo-Hyung; Yoon, Jun-Bo; Choi, Yang-Kyu

    2010-11-16

    A polydimethylsiloxane (PDMS) elastomer surface with perfectly ordered microstructures having an inverse-trapezoidal cross-sectional profile (simply PDMS trapezoids) showed superhydrophobic and transparent characteristics under visible light as reported in our previous work. The addition of a fluoropolymer (Teflon) coating enhances both features and provides oleophobicity. This paper focuses on the analytical modeling of the fabricated PDMS trapezoids structure and thermodynamic analysis based on the Gibbs free energy analysis. Additionally, the wetting characteristics of the fabricated PDMS trapezoids surface before and after the application of the Teflon coating are analytically explained. The Gibbs free energy analysis reveals that, due to the Teflon coating, the Cassie-Baxter state becomes energetically more favorable than the Wenzel state and the contact angle difference between the Cassie-Baxter state and the Wenzel state decreases. These two findings support the robustness of the superhydrophobicity of the fabricated Teflon-coated PDMS trapezoids. This is then verified via the impinging test of a water droplet at a high speed. The dependencies of the design parameters in the PDMS trapezoids on the hydrophobicity are also comprehensively studied through a thermodynamic analysis. Geometrical dependency on the hydrophobicity shows that overhang microstructures do not have a significant influence on the hydrophobicity. In contrast, the intrinsic contact angle of the structural material is most important in determining the apparent contact angle. On the other hand, the experimental results showed that the side angles of the overhangs are critical not for the hydrophobic but for the oleophobic property with liquids of a low surface tension. Understanding of design parameters in the PDMS trapezoids surface gives more information for implementation of superhydrophobic surfaces.

  12. The sensitivity of surface mass loading displacement response to perturbations in the elastic structure of the crust and mantle

    Science.gov (United States)

    Martens, Hilary R.; Rivera, Luis; Simons, Mark; Ito, Takeo

    2016-05-01

    Surface mass loads generate a rich spectrum of deformation responses in the solid Earth that might be exploited to probe the material properties of the crust and mantle. Here we present a detailed examination of load-induced surface displacements and their sensitivities to systematic perturbations in elastic Earth structure. We compute Love numbers and displacement load Green's functions (LGFs) by integrating the equations of motion for spheroidal deformation of a radially heterogeneous and self-gravitating Earth. Sensitivity kernels are derived for individual Love numbers numerically using finite differences and quasi-analytically using calculus of variations. We then generate sensitivity kernels for displacement LGFs by systematically perturbing the preliminary reference Earth model. We find that displacement LGFs are most sensitive to elastic structural perturbations within 500 km depth from the surface and for short source-receiver distances. For separate perturbations to the shear modulus, bulk modulus, and density within the crust and mantle, the sensitivity kernels exhibit unique patterns, consistent with the possibility to constrain the parameters independently given a spatially distributed set of sufficiently accurate loading response observations. The sensitivity to density structure, however, is generally weak in comparison to elastic structure. We also examine the sensitivity of surface displacements caused by M2 ocean tidal loading (OTL) to systematic perturbations in the elastic moduli and density. Since OTL-induced surface displacements are load and site dependent, we focus on high-resolution profiles across Iceland as a case study. The sensitivity kernels constitute a key element in the formulation of the inverse problem with application to geodetic tomography.

  13. Reliability-based design and load tolerance evaluation using stochastic response surface and probabilistic sensitivities

    Science.gov (United States)

    Wang, Haoyu

    Uncertainty is inevitable in structural design. This research presents an efficient uncertainty analysis technique based on stochastic response surfaces (SRS). The focus is on calculating uncertainty propagation using fewer number of function evaluations. Due to sensitivity analysis, the gradient information of the performance is efficiently calculated and used in constructing SRS. Based on SRS, reliability-based design optimization (RBDO) is studied intensively in this research. Probability sensitivity analysis using the sampling technique is also proposed. Since the computational cost of RBDO increases significantly proportional to the increasing number of random variables, global sensitivity analysis is introduced to adaptively reduce unessential random variables. It has been shown that the global sensitivity indices can be calculated analytically because the SRS employs the Hermite polynomials as bases. Traditional structural design focuses on designing a reliable structure under well characterized random factors (dimensions, shape, material properties, etc). Variations of these parameters are relatively small and well characterized. However, everyday engineering life tends to use the existing structural part in a different applications instead of designing a completely new part. In this research, a reliability-based safety envelope concept for load tolerance is introduced. This shows the capacity of the current design as a future reference for design upgrade, maintenance and control. The safety envelope is applied to estimate the load tolerance of a structural part with respect to the reliability of fatigue life. Stochastic response surface is also applied on robust design in this research. It is shown that the polynomial chaos expansion with appropriate bases provides an accurate and efficient tool in evaluating the performance variance. In addition, the sensitivity of the output variance, which is critical in the mathematical programming method, is

  14. Analytical real-time measurement of a three-dimensional weld pool surface

    Science.gov (United States)

    Zhang, WeiJie; Wang, XueWu; Zhang, YuMing

    2013-11-01

    The ability to observe and measure weld pool surfaces in real-time is the core of the foundation for next generation intelligent welding that can partially imitate skilled welders who observe the weld pool to acquire information on the welding process. This study aims at the real-time measurement of the specular three-dimensional (3D) weld pool surface under a strong arc in gas tungsten arc welding (GTAW). An innovative vision system is utilized in this study to project a dot-matrix laser pattern on the specular weld pool surface. Its reflection from the surface is intercepted at a distance from the arc by a diffuse plane. The intercepted laser dots illuminate this plane producing an image showing the reflection pattern. The deformation of this reflection pattern from the projected pattern (e.g. the dot matrix) is used to derive the 3D shape of the reflection surface, i.e., the weld pool surface. Based on careful analysis, the underlying reconstruction problem is formulated mathematically. An analytic solution is proposed to solve this formulated problem resulting in the weld pool surface being reconstructed on average in 3.04 ms during welding experiments. A vision-based monitoring system is thus established to measure the weld pool surface in GTAW in real-time. In order to verify the effectiveness of the proposed reconstruction algorithm, first numerical simulation is conducted. The proposed algorithm is then tested on a spherical convex mirror with a priori knowledge of its geometry. The detailed analysis of the measurement error validates the accuracy of the proposed algorithm. Results from the real-time experiments verify the robustness of the proposed reconstruction algorithm.

  15. Feature-resolved computational and analytical study of laminar drag reduction by superhydrophobic surfaces

    Science.gov (United States)

    Li, Yixuan; Alame, Karim; Mahesh, Krishnan

    2017-05-01

    Direct numerical simulations are used to study the drag reduction by superhydrophobic surfaces in laminar channel flow. Resolved multiphase simulations using the volume of fluid methodology are performed to study the effects of groove geometry, interface shear rate, and meniscus penetration independently. An analytical solution for the flow in a laminar channel with a grooved surface with a gas pocket within is obtained. The solution accounts for both the groove geometry and the trapped fluid properties, and shows good agreement with simulation results. The solution is used to propose a scaling law that collapses data across fully wetted to fully gas-filled regimes. The trapped gas is simulated as both flat and meniscal interfaces. The drag reduction initially increases with interface deflection into the groove and then decreases for large deflections as the interface velocity approaches zero due to the proximity to the bottom of the groove.

  16. Analytical prediction of sub surface thermal history in translucent tissue phantoms during plasmonic photo thermotherapy

    CERN Document Server

    Dhar, Purbarun; Narasimhan, Arunn; Das, Sarit K

    2015-01-01

    Knowledge of thermal history in biological tissues during laser based hyperthermia is essential to achieve necrosis of tumour orcarcinoma cells. A semi analytical model to predict sub surface thermal history in translucent, soft, bio tissue mimics has been proposed. The model can accurately predict the spatio temporal temperature variations along depth and the anomalous thermal behaviour in such media, viz. occurrence of sub surface temperature peaks. Based on opto thermal properties, the augmented temperature and shift of the peak positions in case of gold nanostructure mediated tissue phantom hyperthermia can be predicted. Employing inverse approach, the absorbance coefficient of nano graphene infused tissue mimics is determined from the peak temperature and found to provide appreciably accurate predictions along depth. Furthermore, a simplistic, dimensionally consistent correlation to theoretically determine the position of the peak in such media is proposed and found to be consistent with experiments and ...

  17. Analytical formula of rectangular surface mobility of an infinite plate and the parameters influences

    Institute of Scientific and Technical Information of China (English)

    DAI Jue

    2003-01-01

    This paper investigates the characteristics of surface mobility when power transmission over the contact area between sub-structures is considered. An analytical formula of the surface mobility of an infinite homogeneous plate over a rectangular contact area subject to a uniform, conphase force excitation is derived by using complex power method and the concept of structural intensity. This formula provides a theoretical tool for investigating power transmission over the contact area between sub-structures. The influences of the size, the dimension and the aspect ratio of the contact area on power transmission are analyzed and described according to the results calculated, that provides an effectively theoretical method for investigation of vibration isolation.

  18. An analytical and numerical study of the nonlinear reflection at a stress-free surface

    Science.gov (United States)

    Romer, Anne; Kim, Jin-Yeon; Jacobs, Laurence J.

    2015-03-01

    Implementation of the ultrasonic second harmonic generation has typically been restricted to simple setups such as through-transmission or Rayleigh surface waves. Recent research has evaluated the second harmonic waves generation in P- and SV- waves reflected from a stress-free surface to enable the single-sided interrogation of a specimen. This research considers the second harmonic generation in an aluminum specimen, which is analytically evaluated using an approach based on a perturbation method. Here, the model is chosen to mimic an experimental setup where the longitudinal wave is generated at oblique angle using a wedge transducer. Due to the mode conversion at the interface of the wedge and the specimen, it is necessary to evaluate longitudinal and shear waves, determining all second harmonic waves generated in the bulk and at the stress-free boundary. The theoretically developed model is then implemented in a commercial finite element code, COMSOL, using increasing fundamental wave amplitudes for different values of third order elastic constants. The results of this computational model verify the analytical approach and the proposed measurement setup, taking into account assumptions and approximations of the solution procedure. Furthermore, the computational model is used to draw important conclusions relevant to the experimental setup, including the need to avoid interaction with diffracted waves.

  19. An analytical and numerical study of the nonlinear reflection at a stress-free surface

    Energy Technology Data Exchange (ETDEWEB)

    Romer, Anne, E-mail: anne.romer@gmx.net; Kim, Jin-Yeon, E-mail: anne.romer@gmx.net [School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332 (United States); Jacobs, Laurence J. [School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA and G.W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332 (United States)

    2015-03-31

    Implementation of the ultrasonic second harmonic generation has typically been restricted to simple setups such as through-transmission or Rayleigh surface waves. Recent research has evaluated the second harmonic waves generation in P- and SV- waves reflected from a stress-free surface to enable the single-sided interrogation of a specimen. This research considers the second harmonic generation in an aluminum specimen, which is analytically evaluated using an approach based on a perturbation method. Here, the model is chosen to mimic an experimental setup where the longitudinal wave is generated at oblique angle using a wedge transducer. Due to the mode conversion at the interface of the wedge and the specimen, it is necessary to evaluate longitudinal and shear waves, determining all second harmonic waves generated in the bulk and at the stress-free boundary. The theoretically developed model is then implemented in a commercial finite element code, COMSOL, using increasing fundamental wave amplitudes for different values of third order elastic constants. The results of this computational model verify the analytical approach and the proposed measurement setup, taking into account assumptions and approximations of the solution procedure. Furthermore, the computational model is used to draw important conclusions relevant to the experimental setup, including the need to avoid interaction with diffracted waves.

  20. Analytical Study of the Effect of the System Geometry on Photon Sensitivity and Depth of Interaction of Positron Emission Mammography

    Directory of Open Access Journals (Sweden)

    Pablo Aguiar

    2012-01-01

    Full Text Available Positron emission mammography (PEM cameras are novel-dedicated PET systems optimized to image the breast. For these cameras it is essential to achieve an optimum trade-off between sensitivity and spatial resolution and therefore the main challenge for the novel cameras is to improve the sensitivity without degrading the spatial resolution. We carry out an analytical study of the effect of the different detector geometries on the photon sensitivity and the angle of incidence of the detected photons which is related to the DOI effect and therefore to the intrinsic spatial resolution. To this end, dual head detectors were compared to box and different polygon-detector configurations. Our results showed that higher sensitivity and uniformity were found for box and polygon-detector configurations compared to dual-head cameras. Thus, the optimal configuration in terms of sensitivity is a PEM scanner based on a polygon of twelve (dodecagon or more detectors. We have shown that this configuration is clearly superior to dual-head detectors and slightly higher than box, octagon, and hexagon detectors. Nevertheless, DOI effects are increased for this configuration compared to dual head and box scanners and therefore an accurate compensation for this effect is required.

  1. Electrospun TiO₂ nanofelt surface-decorated with Ag nanoparticles as sensitive and UV-cleanable substrate for surface enhanced Raman scattering.

    Science.gov (United States)

    Zhao, Yong; Sun, Lei; Xi, Min; Feng, Quan; Jiang, Chaoyang; Fong, Hao

    2014-04-23

    In this study, the free-standing electrospun nanofibrous mat (i.e., nanofelt) consisting of anatase-phase TiO2 nanofibers with diameters of ∼200 nm was prepared, and the nanofelt was subsequently surface-decorated with Ag nanoparticles via an electroless plating method. The sensitivity toward surface enhanced Raman scattering (SERS) and UV-cleanable property of electrospun TiO2/Ag nanofelt were then investigated. In the SERS tests, the target analyte (i.e., 4-mercaptobenzoic acid, Rhodamine 6G, and 4-aminothiophenol) was first adsorbed onto the TiO2/Ag nanofelt as the probe analyte; this was followed by the measurements of Raman intensity and SERS maps. Thereafter, the nanofelt adsorbed with target analyte was cleaned and regenerated/recovered upon UV irradiation in O2-saturated water, and the removal of target analyte was attributed to photodegradation property of anatase-phase TiO2. This study suggested that the electrospun TiO2/Ag nanofelt would be promising as SERS-active substrate with UV-cleanable property for cost-effective and reproducible SERS applications.

  2. Anxiety Sensitivity and the Anxiety Disorders: A Meta-Analytic Review and Synthesis

    Science.gov (United States)

    Olatunji, Bunmi O.; Wolitzky-Taylor, Kate B.

    2009-01-01

    There has been significant interest in the role of anxiety sensitivity (AS) in the anxiety disorders. In this meta-analysis, we empirically evaluate differences in AS between anxiety disorders, mood disorders, and nonclinical controls. A total of 38 published studies (N = 20,146) were included in the analysis. The results yielded a large effect…

  3. Analytical Modeling of Surface Roughness, Hardness and Residual Stress Induced by Deep Rolling

    Science.gov (United States)

    Magalhães, Frederico C.; Abrão, Alexandre M.; Denkena, Berend; Breidenstein, Bernd; Mörke, Tobias

    2016-12-01

    Deep rolling is a mechanical surface treatment that can significantly alter the features of metallic components and despite the fact that it has been used for a long time, to date the influence of the interaction among the principal process parameters has not been thoroughly understood. Aiming to fulfill this gap, this work addresses the effect of deep rolling on surface finish and mechanical properties from the analytical and experimental viewpoints. More specifically, the influence of deep rolling pressure and number of passes on surface roughness, hardness and residual stress induced on AISI 1060 steel is investigated. The findings indicate that the surface roughness after deep rolling is closely related to the yield strength of the work material and the available models can satisfactorily predict the former parameter. Better agreement between the mathematical and experimental hardness values is achieved when a single deep rolling pass is employed, as well as when the yield strength of the work material increases. Compressive residual stress is generally induced after deep rolling, irrespectively of the selected heat treatment and deep rolling parameters. Finally, the model proposed to predict residual stress provides results closest to the experimental data especially when the annealed material is considered.

  4. Analytical Round Robin for Elastic-Plastic Analysis of Surface Cracked Plates, Phase II Results

    Science.gov (United States)

    Allen, P. A.; Wells, D. N.

    2017-01-01

    The second phase of an analytical round robin for the elastic-plastic analysis of surface cracks in flat plates was conducted under the auspices of ASTM Interlaboratory Study 732. The interlaboratory study (ILS) had 10 participants with a broad range of expertise and experience, and experimental results from a surface crack tension test in 4142 steel plate loaded well into the elastic-plastic regime provided the basis for the study. The participants were asked to evaluate a surface crack tension test according to the version of the surface crack initiation toughness testing standard published at the time of the ILS, E2899-13. Data were provided to each participant that represent the fundamental information that would be provided by a mechanical test laboratory prior to evaluating the test result. Overall, the participant’s test analysis results were in good agreement and constructive feedback was received that has resulted in an improved published version of the standard E2899-15.

  5. Covalent functionalization of single-walled carbon nanotubes with polytyrosine: Characterization and analytical applications for the sensitive quantification of polyphenols.

    Science.gov (United States)

    Eguílaz, Marcos; Gutiérrez, Alejandro; Gutierrez, Fabiana; González-Domínguez, Jose Miguel; Ansón-Casaos, Alejandro; Hernández-Ferrer, Javier; Ferreyra, Nancy F; Martínez, María T; Rivas, Gustavo

    2016-02-25

    This work reports the synthesis and characterization of single-walled carbon nanotubes (SWCNT) covalently functionalized with polytyrosine (Polytyr); the critical analysis of the experimental conditions to obtain the efficient dispersion of the modified carbon nanotubes; and the analytical performance of glassy carbon electrodes (GCE) modified with the dispersion (GCE/SWCNT-Polytyr) for the highly sensitive quantification of polyphenols. Under the optimal conditions, the calibration plot for the amperometric response of gallic acid (GA) shows a linear range between 5.0 × 10(-7) and 1.7 × 10(-4) M, with a sensitivity of (518 ± 5) m AM(-1) cm(-2), and a detection limit of 8.8 nM. The proposed sensor was successfully used for the determination of total polyphenolic content in tea extracts.

  6. Radionuclide migration through fractured rock for arbitrary-length decay chain: Analytical solution and global sensitivity analysis

    Science.gov (United States)

    Shahkarami, Pirouz; Liu, Longcheng; Moreno, Luis; Neretnieks, Ivars

    2015-01-01

    This study presents an analytical approach to simulate nuclide migration through a channel in a fracture accounting for an arbitrary-length decay chain. The nuclides are retarded as they diffuse in the porous rock matrix and stagnant zones in the fracture. The Laplace transform and similarity transform techniques are applied to solve the model. The analytical solution to the nuclide concentrations at the fracture outlet is governed by nine parameters representing different mechanisms acting on nuclide transport through a fracture, including diffusion into the rock matrices, diffusion into the stagnant water zone, chain decay and hydrodynamic dispersion. Furthermore, to assess how sensitive the results are to parameter uncertainties, the Sobol method is applied in variance-based global sensitivity analyses of the model output. The Sobol indices show how uncertainty in the model output is apportioned to the uncertainty in the model input. This method takes into account both direct effects and interaction effects between input parameters. The simulation results suggest that in the case of pulse injections, ignoring the effect of a stagnant water zone can lead to significant errors in the time of first arrival and the peak value of the nuclides. Likewise, neglecting the parent and modeling its daughter as a single stable species can result in a significant overestimation of the peak value of the daughter nuclide. It is also found that as the dispersion increases, the early arrival time and the peak time of the daughter decrease while the peak value increases. More importantly, the global sensitivity analysis reveals that for time periods greater than a few thousand years, the uncertainty of the model output is more sensitive to the values of the individual parameters than to the interaction between them. Moreover, if one tries to evaluate the true values of the input parameters at the same cost and effort, the determination of priorities should follow a certain

  7. An overview of the environmental applicability of vermicompost: from wastewater treatment to the development of sensitive analytical methods.

    Science.gov (United States)

    Pereira, Madson de Godoi; Neta, Lourdes Cardoso de Souza; Fontes, Maurício Paulo Ferreira; Souza, Adriana Nascimento; Matos, Thaionara Carvalho; Sachdev, Raquel de Lima; dos Santos, Arnaud Victor; da Guarda Souza, Marluce Oliveira; de Andrade, Marta Valéria Almeida Santana; Paulo, Gabriela Marinho Maciel; Ribeiro, Joselito Nardy; Ribeiro, Araceli Verónica Flores Nardy

    2014-01-01

    The use of vermicompost (humified material) for treating wastewaters, remediating polluted soils, improving agricultural productivity, protecting crop production, and developing sensitive analytical methods is reviewed here, covering the past 17 years. The main advantages of vermicompost, considering all applications covered in this paper, comprise (i) easy acquisition, (ii) low costs, (iii) structural, chemical, and biological characteristics responsible for exceptional adsorptive capacities as well as pollutant degradation, and (iv) the promotion of biocontrol. Specifically, for wastewater decontamination, a considerable number of works have verified the adsorption of toxic metals, but the application of vermicompost is still scarce for the retention of organic compounds. Problems related to the final disposal of enriched vermicompost (after treatment steps) are often found, in spite of some successful destinations such as organic fertilizer. For decontaminating soils, the use of vermicompost is quite scarce, mainly for inorganic pollutants. In agricultural productivity and biocontrol, vermicompost imparts remarkable benefits regarding soil aggregation, plant nutrition, and the development of beneficial microorganisms against phytopathogens. Finally, the use of vermicompost in sensitive analytical methods for quantifying toxic metals is the newest application of this adsorbent.

  8. An Overview of the Environmental Applicability of Vermicompost: From Wastewater Treatment to the Development of Sensitive Analytical Methods

    Directory of Open Access Journals (Sweden)

    Madson de Godoi Pereira

    2014-01-01

    Full Text Available The use of vermicompost (humified material for treating wastewaters, remediating polluted soils, improving agricultural productivity, protecting crop production, and developing sensitive analytical methods is reviewed here, covering the past 17 years. The main advantages of vermicompost, considering all applications covered in this paper, comprise (i easy acquisition, (ii low costs, (iii structural, chemical, and biological characteristics responsible for exceptional adsorptive capacities as well as pollutant degradation, and (iv the promotion of biocontrol. Specifically, for wastewater decontamination, a considerable number of works have verified the adsorption of toxic metals, but the application of vermicompost is still scarce for the retention of organic compounds. Problems related to the final disposal of enriched vermicompost (after treatment steps are often found, in spite of some successful destinations such as organic fertilizer. For decontaminating soils, the use of vermicompost is quite scarce, mainly for inorganic pollutants. In agricultural productivity and biocontrol, vermicompost imparts remarkable benefits regarding soil aggregation, plant nutrition, and the development of beneficial microorganisms against phytopathogens. Finally, the use of vermicompost in sensitive analytical methods for quantifying toxic metals is the newest application of this adsorbent.

  9. High sensitivity detection of bacteria by surface plasmon resonance enhanced common path interferometry

    Science.gov (United States)

    Greef, Charles; Petropavlovskikh, Viatcheslav; Nilsen, Oyvind; Hacioglu, Bilge; Khattatov, Boris; Hall, John

    2007-04-01

    Real time monitoring of biowarfare agents (BWA) for military and civilian protection remains a high priority for homeland security and battlefield readiness. Available devices have adequate sensitivity, but the detection modules have limited periods of deployment, require frequent maintenance, employ single-use disposable components, and have limited multiplexing capability. Surface Plasmon Resonance enhanced Common Path Interferometry (SPR-CPI) is a label-free, high sensitivity biomolecular interaction measurement technology that allows multiplexed real-time measurement of biowarfare agents, including small molecules, proteins, and microbes. The technology permits continuous operation in a field-deployable detection module of an integrated BWA monitoring system. SPR-CPI measures difference in phase shift of polarized light reflected from the transducer interface caused by changes in refractive index induced by biomolecular interactions. The measurement is performed on a discrete 2-dimensional area functionalized with biomolecule capture reagents in a microarray format, allowing simultaneous measurement of up to 100 separate analytes. Output consists of simultaneous voltage measurements proportional to the phase differences resulting from the refractive index changes and is automatically processed and displayed graphically or delivered to a decision making algorithm. This enables a fully automatic field-deployable detection system capable of integration into existing modular BWA detection systems. Proof-of-concept experiments on surrogate models of anticipated BWA threats have demonstrated utility. Efforts are in progress for full development and deployment of the device.

  10. Mechanism of Surface-Enhanced Raman Scattering and Its Application to Highly Sensitive Protein Detection

    Institute of Scientific and Technical Information of China (English)

    Ozaki Y; Itoh T; Yoshida K; Kitahama y; Han X X; Zhao B

    2009-01-01

    @@ Surface-enhanced resonance Raman scattering(SERRS)has recently attracted great interest in analytical science due to enormous enhancement factors that have decreased the detection limits of a wide variety of molecules tO the single molecule level.The SERRS-electromagnetic(EM)model describes single-molecule SERRS sensitivity at interparticle junctions and at sharp edges in Ag and Au nanoaggregatcs based on the fourth power of a local EM-field enhancement factor M The realization of SERRS enhancement factors |M|4 of up to 1014has made single-molecule sensitivity realistic.In other words,twofold EM enhancement processes are important for verifying SERRS enhancement factors that enable single molecules to be detected:in these processes the first enhancement iS due to coupling between incident photons and plasmons and the second enhancement is due tO coupling between SERRS photons and plasmons.The relationship between plasmon resonance,the SERRS intensity,and Ag-nanoparticle microstructures was comprehensively studied to verify EM enhancement in SERRS.However,the first and second enhancements were not treated independently in these investigations and thus they were not able tO provide conclusive evidence for twofold EM enhancements.

  11. Selection of overburden surface mining method in West Virginia by analytical hierarchy process

    Institute of Scientific and Technical Information of China (English)

    Timothy A.Nolan; Vladislav Kecojevic

    2014-01-01

    The broad objective of this research was to improve current surface mining practices and reduce negative environmental impact of overburden removal in West Virginia (WV). The specific objectives were to (i) compare con-ventional surface mining method (drilling, blasting, digging, and loading) to a surface miner (SM) method, and (ii) apply the analytical hierarchy process (AHP) to help select the optimal mining method based on production, cost and envi-ronmental criteria. The design and the procedures used in this research involve five interrelated modules:(i) rock properties of overburden in WV, (ii) drilling and blasting, (iii) digging and loading, (iv) SM method, and (v) comparative analysis and selection of the optimal mining method by AHP. Results of this research indicate that application of SM method would yield higher cost of overburden removal than conventional mining methods in rocks with a high unconfined compressive strength and abrasivity. A significant advantage of SM method, where applicable, is the elimination of the negative environmental impacts associated with blasting.

  12. An Analytical Model for Adsorption and Diffusion of Atoms/Ions on Graphene Surface

    Directory of Open Access Journals (Sweden)

    Yan-Zi Yu

    2015-01-01

    Full Text Available Theoretical investigations are made on adsorption and diffusion of atoms/ions on graphene surface based on an analytical continuous model. An atom/ion interacts with every carbon atom of graphene through a pairwise potential which can be approximated by the Lennard-Jones (L-J potential. Using the Fourier expansion of the interaction potential, the total interaction energy between the adsorption atom/ion and a monolayer graphene is derived. The energy-distance relationships in the normal and lateral directions for varied atoms/ions, including gold atom (Au, platinum atom (Pt, manganese ion (Mn2+, sodium ion (Na1+, and lithium-ion (Li1+, on monolayer graphene surface are analyzed. The equilibrium position and binding energy of the atoms/ions at three particular adsorption sites (hollow, bridge, and top are calculated, and the adsorption stability is discussed. The results show that H-site is the most stable adsorption site, which is in agreement with the results of other literatures. What is more, the periodic interaction energy and interaction forces of lithium-ion diffusing along specific paths on graphene surface are also obtained and analyzed. The minimum energy barrier for diffusion is calculated. The possible applications of present study include drug delivery system (DDS, atomic scale friction, rechargeable lithium-ion graphene battery, and energy storage in carbon materials.

  13. Nickel Alloy Primary Water Bulk Surface and SCC Corrosion Film Analytical Characterization and SCC Mechanistic Implications

    Energy Technology Data Exchange (ETDEWEB)

    Morton, D.; Lewis, N.; Hanson, M.; Rice, S.; Sanders, P.

    2007-04-18

    Alloy 600 corrosion coupon tests were performed: (1) to quantify the temperature dependency of general corrosion and (2) to characterize the composition and structure of bulk surface corrosion films for comparison with ongoing primary water SCC (PWSCC) crack tip corrosion film analyses. Results suggest that the thermal activation energy of Alloy 600 corrosion is consistent with the thermal activation energy of nickel alloy PWSCC. Analytical investigations of the structure and composition of Alloy 600 bulk surface corrosion oxides revealed a duplex (inner and outer) oxide layer structure. The outer layer is discontinuous and comprised of relatively large (1 to 3 {micro}m) nickel ferrite crystals and smaller ({approx}0.1 {micro}m) chromium containing nickel ferrite crystals. The inner layer consists of a relatively continuous chromite spinel (major phase) and chromia (Cr{sub 2}O{sub 3} minor phase) which formed through non-selective oxidation. Chromia and dealloyed Alloy 600 (highly Ni enriched metal) were only observed at 337 C (640 F) and only along the boundaries of deformation induced fine grains and subcells. Specimens having deformation free surfaces exhibited continuous uniform inner chromite spinel oxide layers. Specimens with machining induced surface deformation produced non-uniform inner layer oxides (chromite spinel, Cr{sub 2}O{sub 3} and unoxidized material). PWSCC crack tip oxides, in contrast, were fine grain (no duplex structure) and consisted of both chromium rich spinels and ''NiO'' structure oxides. Generally, nickel rich oxides were more abundant under more oxidized conditions (reduced coolant hydrogen) and spinel rich crack tip oxides were favored under more reducing conditions (increased coolant hydrogen). Bulk surface corrosion film thickness did not correlate with observed SCC growth rates. These results suggest that corrosion is not the rate controlling step of PWSCC but rather that PWSCC and corrosion have a common rate

  14. Analytical Solution for Elliptical Cloaks Based on The Frequency Selective Surface

    Directory of Open Access Journals (Sweden)

    E. Ghasemi Mizuji

    2015-01-01

    Full Text Available In this paper the elliptical dielectric cylinder which is covered with FSS cloak is considered. Frequency selective surface cloak which Alu named it mantle cloak is one of the recent techniques for cloaking. In this method an appropriate FSS can act as cloaking device for suppressing  the scattering of object  in the desired frequency. With using this method the dimension of the cloaks is extremely reduced. By this proposed structure, the RCS of elliptical cylinder  is reduced about 10-20 dB and designed cloak has an appropriate performance.  The analytical solution for the wave in each layer is presented and with using simulation, the electric field and the scattering pattern has been drawn.

  15. Sensitivity of fish density estimates to standard analytical procedures applied to Great Lakes hydroacoustic data

    Science.gov (United States)

    Kocovsky, Patrick M.; Rudstam, Lars G.; Yule, Daniel L.; Warner, David M.; Schaner, Ted; Pientka, Bernie; Deller, John W.; Waterfield, Holly A.; Witzel, Larry D.; Sullivan, Patrick J.

    2013-01-01

    Standardized methods of data collection and analysis ensure quality and facilitate comparisons among systems. We evaluated the importance of three recommendations from the Standard Operating Procedure for hydroacoustics in the Laurentian Great Lakes (GLSOP) on density estimates of target species: noise subtraction; setting volume backscattering strength (Sv) thresholds from user-defined minimum target strength (TS) of interest (TS-based Sv threshold); and calculations of an index for multiple targets (Nv index) to identify and remove biased TS values. Eliminating noise had the predictable effect of decreasing density estimates in most lakes. Using the TS-based Sv threshold decreased fish densities in the middle and lower layers in the deepest lakes with abundant invertebrates (e.g., Mysis diluviana). Correcting for biased in situ TS increased measured density up to 86% in the shallower lakes, which had the highest fish densities. The current recommendations by the GLSOP significantly influence acoustic density estimates, but the degree of importance is lake dependent. Applying GLSOP recommendations, whether in the Laurentian Great Lakes or elsewhere, will improve our ability to compare results among lakes. We recommend further development of standards, including minimum TS and analytical cell size, for reducing the effect of biased in situ TS on density estimates.

  16. Surface analytical characterization of Streptavidin/poly(3-hexylthiophene) bilayers for bio-electronic applications

    Science.gov (United States)

    Sportelli, M. C.; Picca, R. A.; Manoli, K.; Re, M.; Pesce, E.; Tapfer, L.; Di Franco, C.; Cioffi, N.; Torsi, L.

    2017-10-01

    The analytical performance of bioelectronic devices is highly influenced by their fabrication methods. In particular, the final architecture of field-effect transistor biosensors combining spin-cast poly(3-hexylthiophene) (P3HT) film and a biomolecule interlayer deposited on a SiO2/Si substrate can lead to the development of highly performing sensing systems, such as for the case of streptavidin (SA) used for biotin sensing. To gain a better understanding of the quality of the interfacial area, critical is the assessment of the morphological features characteristic of the adopted biolayer deposition protocol, namely: the layer-by-layer (LbL) approach and the spin coating technique. The present study relies on a combined surface spectroscopic and morphological characterization. Specifically, X-ray photoelectron spectroscopy operated in the parallel angle-resolved mode allowed the non-destructive investigation of the in-depth chemical composition of the SA film, alone or in the presence of the P3HT overlayer. Spectroscopic data were supported and corroborated by the results obtained with a Scanning Electron and a Helium Ion microscope investigation performed on the SA layer that provided relevant information on the protein structural arrangement or on its surface morphology. Clear differences emerged between the SA layers prepared by the two approaches, with the layer-by-layer deposition resulting in a smoother and better defined bio-electronic interface. Such findings support the superior analytical performance shown by bioelectronic devices based on LbL-deposited protein layers over spin coated ones.

  17. Increasing the analytical sensitivity by oligonucleotides modified with para- and ortho-twisted intercalating nucleic acids--TINA.

    Directory of Open Access Journals (Sweden)

    Uffe V Schneider

    Full Text Available The sensitivity and specificity of clinical diagnostic assays using DNA hybridization techniques are limited by the dissociation of double-stranded DNA (dsDNA antiparallel duplex helices. This situation can be improved by addition of DNA stabilizing molecules such as nucleic acid intercalators. Here, we report the synthesis of a novel ortho-Twisted Intercalating Nucleic Acid (TINA amidite utilizing the phosphoramidite approach, and examine the stabilizing effect of ortho- and para-TINA molecules in antiparallel DNA duplex formation. In a thermal stability assay, ortho- and para-TINA molecules increased the melting point (Tm of Watson-Crick based antiparallel DNA duplexes. The increase in Tm was greatest when the intercalators were placed at the 5' and 3' termini (preferable or, if placed internally, for each half or whole helix turn. Terminally positioned TINA molecules improved analytical sensitivity in a DNA hybridization capture assay targeting the Escherichia coli rrs gene. The corresponding sequence from the Pseudomonas aeruginosa rrs gene was used as cross-reactivity control. At 150 mM ionic strength, analytical sensitivity was improved 27-fold by addition of ortho-TINA molecules and 7-fold by addition of para-TINA molecules (versus the unmodified DNA oligonucleotide, with a 4-fold increase retained at 1 M ionic strength. Both intercalators sustained the discrimination of mismatches in the dsDNA (indicated by ΔTm, unless placed directly adjacent to the mismatch--in which case they partly concealed ΔTm (most pronounced for para-TINA molecules. We anticipate that the presented rules for placement of TINA molecules will be broadly applicable in hybridization capture assays and target amplification systems.

  18. Increasing the Analytical Sensitivity by Oligonucleotides Modified with Para- and Ortho-Twisted Intercalating Nucleic Acids – TINA

    Science.gov (United States)

    Schneider, Uffe V.; Géci, Imrich; Jøhnk, Nina; Mikkelsen, Nikolaj D.; Pedersen, Erik B.; Lisby, Gorm

    2011-01-01

    The sensitivity and specificity of clinical diagnostic assays using DNA hybridization techniques are limited by the dissociation of double-stranded DNA (dsDNA) antiparallel duplex helices. This situation can be improved by addition of DNA stabilizing molecules such as nucleic acid intercalators. Here, we report the synthesis of a novel ortho-Twisted Intercalating Nucleic Acid (TINA) amidite utilizing the phosphoramidite approach, and examine the stabilizing effect of ortho- and para-TINA molecules in antiparallel DNA duplex formation. In a thermal stability assay, ortho- and para-TINA molecules increased the melting point (Tm) of Watson-Crick based antiparallel DNA duplexes. The increase in Tm was greatest when the intercalators were placed at the 5′ and 3′ termini (preferable) or, if placed internally, for each half or whole helix turn. Terminally positioned TINA molecules improved analytical sensitivity in a DNA hybridization capture assay targeting the Escherichia coli rrs gene. The corresponding sequence from the Pseudomonas aeruginosa rrs gene was used as cross-reactivity control. At 150 mM ionic strength, analytical sensitivity was improved 27-fold by addition of ortho-TINA molecules and 7-fold by addition of para-TINA molecules (versus the unmodified DNA oligonucleotide), with a 4-fold increase retained at 1 M ionic strength. Both intercalators sustained the discrimination of mismatches in the dsDNA (indicated by ΔTm), unless placed directly adjacent to the mismatch – in which case they partly concealed ΔTm (most pronounced for para-TINA molecules). We anticipate that the presented rules for placement of TINA molecules will be broadly applicable in hybridization capture assays and target amplification systems. PMID:21673988

  19. Track sensitivity and the surface roughness measurements of CR-39 with atomic force microscope

    CERN Document Server

    Yasuda, N; Amemiya, K; Takahashi, H; Kyan, A; Ogura, K

    1999-01-01

    Atomic Force Microscope (AFM) has been applied to evaluate the surface roughness and the track sensitivity of CR-39 track detector. We experimentally confirmed the inverse correlation between the track sensitivity and the roughness of the detector surface after etching. The surface of CR-39 (CR-39 doped with antioxidant (HARZLAS (TD-1)) and copolymer of CR-39/NIPAAm (TNF-1)) with high sensitivity becomes rough by the etching, while the pure CR-39 (BARYOTRAK) with low sensitivity keeps its original surface clarity even for the long etching.

  20. Structure sensitivity of CO dissociation on Rh surfaces

    DEFF Research Database (Denmark)

    Mavrikakis, Manos; Baumer, M.; Freund, H.J.;

    2002-01-01

    Using periodic self-consistent density functional calculations it is shown that the barrier for CO dissociation is similar to120 kJ/mol lower on the stepped Rh(211) surface than on the close-packed Rh(111) surface. The stepped surface binds molecular CO and the dissociation products more strongly...... than the flat surface, but the effect is considerably weaker than the effect of surface structure on the dissociation barrier. Our findings are compared with available experimental data, and the consequences for CO activation in methanation and Fischer-Tropsch reactions are discussed....

  1. Novel Analytic Method for Determining Micro-Doppler Measurement Sensitivity in Life-detection Radar

    Directory of Open Access Journals (Sweden)

    Hu Cheng

    2016-10-01

    Full Text Available In recent years, a new non-contact life detecting device has been developed, known as life-detection radar, which can measure bodily movement and locate human subjects. Typically, the amplitude of the vibration being measured is quite small, so the measurement is easily contaminated by noise in the radar system. To date, there is no effective index for judging the influence of noise on the vibration measurements in this radar system. To solve this problem, in this paper, we define the micro-Doppler measurement sensitivity to analyze the influence of noise on the measurement. We then perform a simulation to generate a performance curve for the radar system.

  2. Integrable perturbed magnetic fields in toroidal geometry: An exact analytical flux surface label for large aspect ratio

    Energy Technology Data Exchange (ETDEWEB)

    Kallinikos, N.; Isliker, H.; Vlahos, L.; Meletlidou, E. [Department of Physics, Aristotle University of Thessaloniki, GR-54124 Thessaloniki (Greece)

    2014-06-15

    An analytical description of magnetic islands is presented for the typical case of a single perturbation mode introduced to tokamak plasma equilibrium in the large aspect ratio approximation. Following the Hamiltonian structure directly in terms of toroidal coordinates, the well known integrability of this system is exploited, laying out a precise and practical way for determining the island topology features, as required in various applications, through an analytical and exact flux surface label.

  3. ANALYTICAL SOLUTION FOR WAVES IN PLANETS WITH ATMOSPHERIC SUPERROTATION. II. LAMB, SURFACE, AND CENTRIFUGAL WAVES

    Energy Technology Data Exchange (ETDEWEB)

    Peralta, J.; López-Valverde, M. A. [Instituto de Astrofísica de Andalucía (CSIC), Glorieta de la Astronomía, 18008 Granada (Spain); Imamura, T. [Institute of Space and Astronautical Science-Japan Aerospace Exploration Agency 3-1-1, Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan); Read, P. L. [Clarendon Laboratory, Department of Physics, University of Oxford, Parks Road, Oxford (United Kingdom); Luz, D. [Centro de Astronomia e Astrofísica da Universidade de Lisboa (CAAUL), Observatório Astronómico de Lisboa, Tapada da Ajuda, 1349-018 Lisboa (Portugal); Piccialli, A., E-mail: peralta@iaa.es [LATMOS, UVSQ, 11 bd dAlembert, 78280 Guyancourt (France)

    2014-07-01

    This paper is the second in a two-part study devoted to developing tools for a systematic classification of the wide variety of atmospheric waves expected on slowly rotating planets with atmospheric superrotation. Starting with the primitive equations for a cyclostrophic regime, we have deduced the analytical solution for the possible waves, simultaneously including the effect of the metric terms for the centrifugal force and the meridional shear of the background wind. In those cases where the conditions for the method of the multiple scales in height are met, these wave solutions are also valid when vertical shear of the background wind is present. A total of six types of waves have been found and their properties were characterized in terms of the corresponding dispersion relations and wave structures. In this second part, we study the waves' solutions when several atmospheric approximations are applied: Lamb, surface, and centrifugal waves. Lamb and surface waves are found to be quite similar to those in a geostrophic regime. By contrast, centrifugal waves turn out to be a special case of Rossby waves that arise in atmospheres in cyclostrophic balance. Finally, we use our results to identify the nature of the waves behind atmospheric periodicities found in polar and lower latitudes of Venus's atmosphere.

  4. Sensitivity enhancement of surface thermal lens technique with a short-wavelength probe beam: Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiaorong [Institute of Optics and Electronics, Chinese Academy of Sciences and Key Laboratory of Optical Engineering, Chinese Academy of Sciences, Chengdu 610209 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Li, Bincheng [Institute of Optics and Electronics, Chinese Academy of Sciences and Key Laboratory of Optical Engineering, Chinese Academy of Sciences, Chengdu 610209 (China)

    2015-02-15

    Surface thermal lens is a highly sensitive photothermal technique to measure low absorption losses of various solid materials. In such applications, the sensitivity of surface thermal lens is a key parameter for measuring extremely low absorption. In this paper, we experimentally investigated the influence of probe beam wavelength on the sensitivity of surface thermal lens for measuring the low absorptance of optical laser components. Three probe lasers with wavelength 375 nm, 633 nm, and 1570 nm were used, respectively, to detect the surface thermal lens amplitude of a highly reflective coating sample excited by a cw modulated Gaussian beam at 1064 nm. The experimental results showed that the maximum amplitude of surface thermal lens signal obtained at corresponding optimized detection distance was inversely proportional to the wavelength of the probe beam, as predicted by previous theoretical model. The sensitivity of surface thermal lens could, therefore, be improved by detecting surface thermal lens signal with a short-wavelength probe beam.

  5. Fabrication of gold nanoparticle-embedded metal-organic framework for highly sensitive surface-enhanced Raman scattering detection.

    Science.gov (United States)

    Hu, Yuling; Liao, Jia; Wang, Dongmei; Li, Gongke

    2014-04-15

    Surface-enhanced Raman scattering (SERS) signals strongly rely on the interactions and distance between analyte molecules and metallic nanostructures. In this work, the use of a gold nanoparticle (AuNP)-embedded metal-organic framework was introduced for the highly sensitive SERS detection. The AuNPs were in situ grown and encapsulated within the host matrix of MIL-101 by a solution impregnation strategy. The as-synthesized AuNPs/MIL-101 nanocomposites combined the localized surface plasmon resonance properties of the gold nanoparticles and the high adsorption capability of metal-organic framework, making them highly sensitive SERS substrates by effectively preconcentrating analytes in close proximity to the electromagnetic fields at the SERS-active metal surface. We discussed the fabrication, physical characterization, and SERS activity of our novel substrates by measuring the Raman signals of a variety of model analytes. The SERS substrate was found to be highly sensitive, robust, and amiable to several different target analytes. A SERS detection limit of 41.75 and 0.54 fmol for Rhodamine 6G and benzadine, respectively, was demonstrated. The substrate also showed high stability and reproducibility, as well as molecular sieving effect thanks to the protective shell of the metal-organic framework. Subsequently, the potential practical application of the novel SERS substrate was evaluated by quantitative analysis of organic pollutant p-phenylenediamine in environmental water and tumor marker alpha-fetoprotein in human serum. The method showed good linearity between 1.0 and 100.0 ng/mL for p-phenylenediamine and 1.0-130.0 ng/mL for alpha-fetoprotein with the correlation coefficients of 0.9950 and -0.9938, respectively. The recoveries ranged from 80.5% to 114.7% for p-phenylenediamine in environmental water and 79.3% to 107.3% for alpha-fetoprotein in human serum. These results foresee promising application of the novel metal-organic framework based composites as

  6. An analytical two-flow model to simulate the distribution of irradiance in coastal waters with a wind-roughed surface and bottom reflectance

    Science.gov (United States)

    Ma, Wei-Ming

    1997-06-01

    An analytical two-flow model is derived from the radiative transfer equation to simulate the distribution of irradiance in coastal waters with a wind-roughed surface and bottom reflectance. The model utilizes unique boundary conditions, including the surface slope of the downwelling and upwelling irradiance as well as the influence of wind and bottom reflectance on simulated surface reflectance. The developed model provides a simple mathematical concept for understanding the irradiant light flux and associated processes in coastal or fresh water as well as turbid estuarine waters. The model is applied to data from the Banana River and coastal Atlantic Ocean water off the east coast of central Florida, USA. The two-flow irradiance model is capable of simulating realistic above-surface reflectance signatures under wind-roughened air-water surface given realistic input parameters including a specular flux conversion coefficient, absorption coefficient, backscattering coefficient, atmospheric visibility, bottom reflectance, and water depth. The root-mean-squared error of the calculated above-surface reflectances is approximately 3% in the Banana River and is less than 15% in coastal Atlantic Ocean off the east of Florida. Result of the subsurface reflectance sensitivity analysis indicates that the specular conversion coefficient is the most sensitive parameter in the model, followed by the beam attenuation coefficient, absorption coefficient, water depth, backscattering coefficient, specular irradiance, diffuse irradiance, bottom reflectance, and wind speed. On the other hand, result of the above-surface reflectance sensitivity analysis indicates that the wind speed is the most important parameter, followed by bottom reflectance, attenuation coefficient, water depth, conversion coefficient, specular irradiance, downwelling irradiance, absorption coefficient, and backscattering coefficient. Model results depend on the accuracy of these parameters to a large degree and

  7. Discrimination between biologically relevant calcium phosphate phases by surface-analytical techniques

    Energy Technology Data Exchange (ETDEWEB)

    Kleine-Boymann, Matthias, E-mail: matthias.kleine-boymann@phys.chemie.uni-giessen.de; Rohnke, Marcus, E-mail: marcus.rohnke@phys.chemie.uni-giessen.de; Henss, Anja, E-mail: anja.henss@phys.chemie.uni-giessen.de; Peppler, Klaus, E-mail: klaus.peppler@phys.chemie.uni-giessen.de; Sann, Joachim, E-mail: joachim.sann@phys.chemie.uni-giessen.de; Janek, Juergen, E-mail: juergen.janek@phys.chemie.uni-giessen.de

    2014-08-01

    The spatially resolved phase identification of biologically relevant calcium phosphate phases (CPPs) in bone tissue is essential for the elucidation of bone remodeling mechanisms and for the diagnosis of bone diseases. Analytical methods with high spatial resolution for the discrimination between chemically quite close phases are rare. Therefore the applicability of state-of-the-art ToF-SIMS, XPS and EDX as chemically specific techniques was investigated. The eight CPPs hydroxyapatite (HAP), β-tricalcium phosphate (β-TCP), α-tricalcium phosphate (α-TCP), octacalcium phosphate (OCP), dicalcium phosphate dihydrate (DCPD), dicalcium phosphate (DCP), monocalcium phosphate (MCP) and amorphous calcium phosphate (ACP) were either commercial materials in high purity or synthesized by ourselves. The phase purity was proven by XRD analysis. All of the eight CPPs show different mass spectra and the phases can be discriminated by applying the principal component analysis method to the mass spectrometric data. The Ca/P ratios of all phosphates were determined by XPS and EDX. With both methods some CPPs can be distinguished, but the obtained Ca/P ratios deviate systematically from their theoretical values. It is necessary in any case to determine a calibration curve, respectively the ZAF values, from appropriate standards. In XPS also the O(1s)-satellite signals are correlated to the CPPs composition. Angle resolved and long-term XPS measurements of HAP clearly prove that there is no phosphate excess at the surface. Decomposition due to X-ray irradiation has not been observed.

  8. Photosynthesis sensitivity to climate change in land surface models

    Science.gov (United States)

    Manrique-Sunen, Andrea; Black, Emily; Verhoef, Anne; Balsamo, Gianpaolo

    2016-04-01

    Accurate representation of vegetation processes within land surface models is key to reproducing surface carbon, water and energy fluxes. Photosynthesis determines the amount of CO2 fixated by plants as well as the water lost in transpiration through the stomata. Photosynthesis is calculated in land surface models using empirical equations based on plant physiological research. It is assumed that CO2 assimilation is either CO2 -limited, radiation -limited ; and in some models export-limited (the speed at which the products of photosynthesis are used by the plant) . Increased levels of atmospheric CO2 concentration tend to enhance photosynthetic activity, but the effectiveness of this fertilization effect is regulated by environmental conditions and the limiting factor in the photosynthesis reaction. The photosynthesis schemes at the 'leaf level' used by land surface models JULES and CTESSEL have been evaluated against field photosynthesis observations. Also, the response of photosynthesis to radiation, atmospheric CO2 and temperature has been analysed for each model, as this is key to understanding the vegetation response that climate models using these schemes are able to reproduce. Particular emphasis is put on the limiting factor as conditions vary. It is found that while at present day CO2 concentrations export-limitation is only relevant at low temperatures, as CO2 levels rise it becomes an increasingly important restriction on photosynthesis.

  9. Focus variation microscope: linear theory and surface tilt sensitivity.

    Science.gov (United States)

    Nikolaev, Nikolay; Petzing, Jon; Coupland, Jeremy

    2016-05-01

    In a recent publication [3rd International Conference on Surface Metrology, Annecy, France, 2012, p. 1] it was shown that surface roughness measurements made using a focus variation microscope (FVM) are influenced by surface tilt. The effect appears to be most significant when the surface has microscale roughness (Ra≈50  nm) that is sufficient to provide a diffusely scattered signal that is comparable in magnitude to the specular component. This paper explores, from first principles, image formation using the focus variation method. With the assumption of incoherent scattering, it is shown that the process is linear and the 3D point spread characteristics and transfer characteristics of the instrument are well defined. It is argued that for the case of microscale roughness and through the objective illumination, the assumption of incoherence cannot be justified and more rigorous analysis is required. Using a foil model of surface scattering, the images that are recorded by a FVM have been calculated. It is shown that for the case of through-the-objective illumination at small tilt angles, the signal quality is degraded in a systematic manner. This is attributed to the mixing of specular and diffusely reflected components and leads to an asymmetry in the k-space representation of the output signals. It is shown that by using extra-aperture illumination or tilt angles greater than the acceptance angle of aperture (such that the specular component is lost), the incoherent assumption can be justified once again. The work highlights the importance of using ring-light illumination and/or polarizing optics, which are often available as options on commercial instruments, as a means to mitigate or prevent these effects.

  10. Smart structure with elastomeric contact surface for prosthetic fingertip sensitivity development

    Science.gov (United States)

    Gu, Chunxin; Liu, Weiting; Yu, Ping; Cheng, Xiaoying; Fu, Xin

    2017-09-01

    Current flexible/compliant tactile sensors suffer from low sensitivity and high hysteresis introduced by the essential viscosity characteristic of soft material, either used as compliant sensing element or as flexible coverage. To overcome these disadvantages, this paper focuses on developing a tactile sensor with a smart hybrid structure to obtain comprehensive properties in terms of size, compliance, robustness and pressure sensing ability so as to meet the requirements of limited space applications such as prosthetic fingertips. Employing micro-fabricated tiny silicon-based pressure die as the sensing element, it is easy to have both small size and good mechanical performance. To protect it from potential damage and maintain the compliant surface, a rigid base and a soft layer form a sealed chamber and encapsulate the fixed die together with fluid. The fluid serves as highly efficient pressure propagation media of mechanical stimulus from the compliant skin to the pressure die without any hazard impacting the vulnerable connecting wires. To understand the pressure transmission mechanism, a simplified and concise analytic model of a spring system is proposed. Using easy fabrication technologies, a prototype of a 3 × 3 sensor array with total dimensions of 14 mm × 14 mm × 6.5 mm was developed. Based on the quasi-linear relationship between fluid volume and pressure, finite element modeling was developed to analyze the chamber deformation and pressure output of the sensor cell. Experimental tests of the sensor prototype were implemented. The results showed that the sensor cell had good sensing performance with sensitivity of 19.9 mV N-1, linearity of 0.998, repeatability error of 3.41%, and hysteresis error of 3.34%. The force sensing range was from 5 mN to 1.6 N.

  11. Design of Highly Sensitive Surface Plasmon Resonance Sensors Using Planar Metallic Films Closely Coupled to Nanogratings

    Institute of Scientific and Technical Information of China (English)

    YANG Xiao-Yan; XIE Wen-Chong; LIU De-Ming

    2008-01-01

    We investigate the sensitivity enhancement of surface plasmon resonance(SPR)sensors using planar metallic films closely coupled to nanogratings.The strong coupling between localized surface plasmon resonances(LSPRs)presenting in metallic nanostructures and surface plasmon polaritons(SPPs)propagating at the metallic film surface leads to changes of resonance reflection properties,resulting in enhanced sensitivity of SPR sensors.The effects of thickness of the metallic films,grating period and metal materials on the refractive index sensitivity of the device are investigated.The refractive index sensitivity of nanograting-based SPR sensors is predicted to be about 543 nm/RIU(refractive index unit)using optimized structure parameters.Our study on SPR sensors using planar metallic films closely coupled to nanogratings demonstrates the potential for significant improvement in refractive index sensitivity.

  12. Near-surface sensitivity suppression way for diffuse reflective optical tomography: simulation and a phantom study

    Science.gov (United States)

    Fukuda, Keiko; Fujii, Mamiko

    2007-07-01

    Diffuse reflective optical measurement is a useful approach for monitoring the oxygen consumption of living tissue such as brain and muscle. To improve the oxygen consumption measurement accuracy, we propose a method for suppressing the near-surface sensitivity. Diffuse reflective light is detected at the aperture used for irradiating the light and is used as a cancellation signal for near-field sensitivity in the conventional measurement scheme. Photon fluence density functions and positional dependences of detected light sensitivity to change in absorbance were simulated. The sensitivity detected at the same position (aperture) as irradiation was significantly high for the near-surface region. With our method, the near-surface sensitivity is reduced by more than 90% while keeping target sensitivity almost constant (only 3% deterioration). The near-surface and deep-field sensitivity was measured with a phantom with light (785 nm) modulated at 1 kHz through an optical fiber bundle. It confirmed suppressed the near-surface sensitivity by subtracting the light detected at the same aperture from the light detected at another aperture.

  13. Global ocean wind power sensitivity to surface layer stability

    Science.gov (United States)

    Capps, Scott B.; Zender, Charles S.

    2009-05-01

    Global ocean wind power has recently been assessed (W. T. Liu et al., 2008) using scatterometry-based 10 m winds. We characterize, for the first time, wind power at 80 m (typical wind turbine hub height) above the global ocean surface, and account for the effects of surface layer stability. Accounting for realistic turbine height and atmospheric stability increases mean global ocean wind power by +58% and -4%, respectively. Our best estimate of mean global ocean wind power is 731 W m-2, about 50% greater than the 487 W m-2 based on previous methods. 80 m wind power is 1.2-1.5 times 10 m power equatorward of 30° latitude, between 1.4 and 1.7 times 10 m power in wintertime storm track regions and >6 times 10 m power in stable regimes east of continents. These results are relatively insensitive to methodology as wind power calculated using a fitted Weibull probability density function is within 10% of power calculated from discrete wind speed measurements over most of the global oceans.

  14. Nano-morphology induced additional surface plasmon resonance enhancement of SERS sensitivity in Ag/GaN nanowall network.

    Science.gov (United States)

    Sharvani, S; Upadhayaya, Kishor; Kumari, Gayatri; Narayana, Chandrabhas; Shivaprasad, S M

    2015-11-20

    The GaN nanowall network, formed by opening the screw dislocations by kinetically controlled MBE growth, possesses a large surface and high conductivity. Sharp apexed nanowalls show higher surface electron concentration in the band-tail states, in comparison to blunt apexed nanowalls. Uncapped silver nanoparticles are vapor deposited on the blunt and sharp GaN nanowall networks to study the morphological dependence of band-edge plasmon-coupling. Surface enhanced Raman spectroscopy studies performed with a rhodamine 6G analyte on these two configurations clearly show that the sharp nanowall morphology with smaller Ag nanoparticles shows higher enhancement of the Raman signal. A very large enhancement factor of 2.8 × 10(7) and a very low limit of detection of 10(-10) M is observed, which is attributed to the surface plasmon resonance owing to the high surface electron concentration on the GaN nanowall in addition to that of the Ag nanoparticles. The significantly higher sensitivity with same-sized Ag nanoparticles confirms the unconventional role of morphology-dependent surface charge carrier concentration of GaN nanowalls in the enhancement of Raman signals.

  15. Sensitivity of land surface and Cumulus schemes for Thunderstorm prediction

    Science.gov (United States)

    Kumar, Dinesh; Mohanty, U. C.; Kumar, Krishan

    2016-06-01

    The cloud processes play an important role in all forms of precipitation. Its proper representation is one of the challenging tasks in mesoscale numerical simulation. Studies have revealed that mesoscale feature require proper initialization which may likely to improve the convective system rainfall forecasts. Understanding the precipitation process, model initial condition accuracy and resolved/sub grid-scale precipitation processes representation, are the important areas which needed to improve in order to represent the mesoscale features properly. Various attempts have been done in order to improve the model performance through grid resolution, physical parameterizations, etc. But it is the physical parameterizations which provide a convective atmosphere for the development and intensification of convective events. Further, physical parameterizations consist of cumulus convection, surface fluxes of heat, moisture, momentum, and vertical mixing in the planetary boundary layer (PBL). How PBL and Cumulus schemes capture the evolution of thunderstorm have been analysed by taking thunderstorm cases occurred over Kolkata, India in the year 2011. PBL and cumulus schemes were customized for WSM-6 microphysics because WSM series has been widely used in operational forecast. Results have shown that KF (PBL scheme) and WSM-6 (Cumulus Scheme) have reproduced the evolution of surface variable such as CAPE, temperature and rainfall very much like observation. Further, KF and WSM-6 scheme also provided the increased moisture availability in the lower atmosphere which was taken to higher level by strong vertical velocities providing a platform to initiate a thunderstorm much better. Overestimation of rain in WSM-6 occurs primarily because of occurrence of melting and freezing process within a deeper layer in WSM-6 scheme. These Schemes have reproduced the spatial pattern and peak rainfall coverage closer to TRMM observation. It is the the combination of WSM-6, and KF schemes

  16. Sensitivity of land surface and Cumulus schemes for Thunderstorm prediction

    Directory of Open Access Journals (Sweden)

    D. Kumar

    2016-06-01

    Full Text Available The cloud processes play an important role in all forms of precipitation. Its proper representation is one of the challenging tasks in mesoscale numerical simulation. Studies have revealed that mesoscale feature require proper initialization which may likely to improve the convective system rainfall forecasts. Understanding the precipitation process, model initial condition accuracy and resolved/sub grid-scale precipitation processes representation, are the important areas which needed to improve in order to represent the mesoscale features properly. Various attempts have been done in order to improve the model performance through grid resolution, physical parameterizations, etc. But it is the physical parameterizations which provide a convective atmosphere for the development and intensification of convective events. Further, physical parameterizations consist of cumulus convection, surface fluxes of heat, moisture, momentum, and vertical mixing in the planetary boundary layer (PBL. How PBL and Cumulus schemes capture the evolution of thunderstorm have been analysed by taking thunderstorm cases occurred over Kolkata, India in the year 2011. PBL and cumulus schemes were customized for WSM-6 microphysics because WSM series has been widely used in operational forecast. Results have shown that KF (PBL scheme and WSM-6 (Cumulus Scheme have reproduced the evolution of surface variable such as CAPE, temperature and rainfall very much like observation. Further, KF and WSM-6 scheme also provided the increased moisture availability in the lower atmosphere which was taken to higher level by strong vertical velocities providing a platform to initiate a thunderstorm much better. Overestimation of rain in WSM-6 occurs primarily because of occurrence of melting and freezing process within a deeper layer in WSM-6 scheme. These Schemes have reproduced the spatial pattern and peak rainfall coverage closer to TRMM observation. It is the the combination of WSM-6

  17. Dynamic performance of frictionless fast shutters for ITER: Numerical and analytical sensitivity study for the development of a test program

    Energy Technology Data Exchange (ETDEWEB)

    Panin, Anatoly, E-mail: a.panin@fz-juelich.de [Forschungszentrum Jülich GmbH, Institut für Energie- und Klimaforschung – Plasmaphysik, 52425 Jülich (Germany); Khovayko, Mikhail [St. Petersburg Polytechnic University, Mechanics and Control Processes Department, Computational Mechanics Laboratory, 195251 St. Petersburg (Russian Federation); Krasikov, Yury [Forschungszentrum Jülich GmbH, Institut für Energie- und Klimaforschung – Plasmaphysik, 52425 Jülich (Germany); Nemov, Alexander [St. Petersburg Polytechnic University, Mechanics and Control Processes Department, Computational Mechanics Laboratory, 195251 St. Petersburg (Russian Federation); Biel, Wolfgang; Mertens, Philippe; Neubauer, Olaf; Schrader, Michael [Forschungszentrum Jülich GmbH, Institut für Energie- und Klimaforschung – Plasmaphysik, 52425 Jülich (Germany)

    2015-10-15

    To prolong a lifetime of the ITER first diagnostic mirrors some protective shutters can be engaged. A concept of an elastic shutter that operates frictionless in vacuum has been studied at the Forschungszentrum Jülich, Germany. Under actuation two shutter arms (∼2 m long) bend laterally between two pairs of limiting bumpers thus shielding the optical aperture or opening it for measurements. To increase the shutter efficiency the transition time between its open and closed states can be minimized. This demands a fast shutter that operates in fractions of a second and exhibit essentially dynamic behavior, like impacts with the bumpers that cause the shutter arms’ bouncing and oscillations. The paper presents numerical studies of the shutter dynamic behavior using the explicit and implicit 3D FE transient structural modeling. Simple 1D analytical model was developed to predict the shutter impact kinetic energy that mostly determines its further dynamic response. The structure sensitivity to different parameters was studied and ways for its optimization were laid down. A parametric shutter mockup with easily changeable mechanical characteristics was manufactured. A test program aimed for further shutter optimization, basing on the analysis performed and engaging powerful capabilities of the parametric shutter mockup is discussed in the paper.

  18. Decay of isolated surface features driven by the Gibbs-Thomson effect in an analytic model and a simulation

    Energy Technology Data Exchange (ETDEWEB)

    McLean, J.G.; Krishnamachari, B.; Peale, D.R. [Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853-2501 (United States); Chason, E. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); Sethna, J.P.; Cooper, B.H. [Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853-2501 (United States)

    1997-01-01

    A theory based on the thermodynamic Gibbs-Thomson relation is presented that provides the framework for understanding the time evolution of isolated nanoscale features (i.e., islands and pits) on surfaces. Two limiting cases are predicted, in which either diffusion or interface transfer is the limiting process. These cases correspond to similar regimes considered in previous works addressing the Ostwald ripening of ensembles of features. A third possible limiting case is noted for the special geometry of {open_quotes}stacked{close_quotes} islands. In these limiting cases, isolated features are predicted to decay in size with a power-law scaling in time: A{proportional_to}(t{sub 0}{minus}t){sup n}, where A is the area of the feature, t{sub 0} is the time at which the feature disappears, and n=2/3 or 1. The constant of proportionality is related to parameters describing both the kinetic and equilibrium properties of the surface. A continuous-time Monte Carlo simulation is used to test the application of this theory to generic surfaces with atomic scale features. A method is described to obtain macroscopic kinetic parameters describing interfaces in such simulations. Simulation and analytic theory are compared directly, using measurements of the simulation to determine the constants of the analytic theory. Agreement between the two is very good over a range of surface parameters, suggesting that the analytic theory properly captures the necessary physics. It is anticipated that the simulation will be useful in modeling complex surface geometries often seen in experiments on physical surfaces, for which application of the analytic model is not straightforward. {copyright} {ital 1997} {ital The American Physical Society}

  19. Decay of isolated surface features driven by the Gibbs-Thomson effect in an analytic model and a simulation

    Science.gov (United States)

    McLean, James G.; Krishnamachari, B.; Peale, D. R.; Chason, E.; Sethna, James P.; Cooper, B. H.

    1997-01-01

    A theory based on the thermodynamic Gibbs-Thomson relation is presented that provides the framework for understanding the time evolution of isolated nanoscale features (i.e., islands and pits) on surfaces. Two limiting cases are predicted, in which either diffusion or interface transfer is the limiting process. These cases correspond to similar regimes considered in previous works addressing the Ostwald ripening of ensembles of features. A third possible limiting case is noted for the special geometry of ``stacked'' islands. In these limiting cases, isolated features are predicted to decay in size with a power-law scaling in time: A~(t0-t)n, where A is the area of the feature, t0 is the time at which the feature disappears, and n=2/3 or 1. The constant of proportionality is related to parameters describing both the kinetic and equilibrium properties of the surface. A continuous-time Monte Carlo simulation is used to test the application of this theory to generic surfaces with atomic scale features. A method is described to obtain macroscopic kinetic parameters describing interfaces in such simulations. Simulation and analytic theory are compared directly, using measurements of the simulation to determine the constants of the analytic theory. Agreement between the two is very good over a range of surface parameters, suggesting that the analytic theory properly captures the necessary physics. It is anticipated that the simulation will be useful in modeling complex surface geometries often seen in experiments on physical surfaces, for which application of the analytic model is not straightforward.

  20. Solar Ion Processing of Major Element Surface Compositions of Mature Mare Soils: Insights from Combined XPS and Analytical TEM Observations

    Science.gov (United States)

    Christoffersen, R.; Dukes, C.; Keller, L. P.; Baragiola, R.

    2012-01-01

    Solar wind ions are capable of altering the sur-face chemistry of the lunar regolith by a number of mechanisms including preferential sputtering, radiation-enhanced diffusion and sputter erosion of space weathered surfaces containing pre-existing compositional profiles. We have previously reported in-situ ion irradiation experiments supported by X-ray photoelectron spectroscopy (XPS) and analytical TEM that show how solar ions potentially drive Fe and Ti reduction at the monolayer scale as well as the 10-100 nm depth scale in lunar soils [1]. Here we report experimental data on the effect of ion irradiation on the major element surface composition in a mature mare soil.

  1. Sensitivity analysis of surface runoff generation in urban flood forecasting.

    Science.gov (United States)

    Simões, N E; Leitão, J P; Maksimović, C; Sá Marques, A; Pina, R

    2010-01-01

    Reliable flood forecasting requires hydraulic models capable to estimate pluvial flooding fast enough in order to enable successful operational responses. Increased computational speed can be achieved by using a 1D/1D model, since 2D models are too computationally demanding. Further changes can be made by simplifying 1D network models, removing and by changing some secondary elements. The Urban Water Research Group (UWRG) of Imperial College London developed a tool that automatically analyses, quantifies and generates 1D overland flow network. The overland flow network features (ponds and flow pathways) generated by this methodology are dependent on the number of sewer network manholes and sewer inlets, as some of the overland flow pathways start at manholes (or sewer inlets) locations. Thus, if a simplified version of the sewer network has less manholes (or sewer inlets) than the original one, the overland flow network will be consequently different. This paper compares different overland flow networks generated with different levels of sewer network skeletonisation. Sensitivity analysis is carried out in one catchment area in Coimbra, Portugal, in order to evaluate overland flow network characteristics.

  2. Geometry-independent neutral desorption device for the sensitive EESI-MS detection of explosives on various surfaces.

    Science.gov (United States)

    Gu, Haiwei; Yang, Shuiping; Li, Jianqiang; Hu, Bin; Chen, Huanwen; Zhang, Lili; Fei, Qiang

    2010-04-01

    A novel geometry-independent neutral desorption (GIND) device was successfully developed, which made neutral desorption (ND) sampling easier and more robust on virtually all types of surfaces. The GIND device features a small air-tight enclosure with fixed space between the ND gas emitter, the sample surface, and the sample collector. Besides easy fabrication and convenient use, this configuration facilitates efficient neutral sample transfer and results in high sensitivity by preventing material loss during the ND process. The effects of various operating parameters of the GIND device such as desorption gas composition, surface wetness, gas flow rate, distance between the surface and the gas emitter, internal diameter of the sample outlet, and GIND device material were experimentally investigated. By using the GIND device, trace amounts of typical explosives such as TNT, RDX, HMX, TATP, etc., were successfully sampled from many different kinds of surfaces, including human skin, glove, glass, envelope, plastic, leather, glass, and clothes. GIND-sampled explosives were detected by multiple-stage extractive electrospray ionization mass spectrometry (EESI-MS). Ion/molecule reactions of explosives such as RDX and TATP were implemented in the EESI source for the rapid detection with enhanced sensitivity and specificity. The typical time for a single sample analysis was a few seconds. Successful transportation of the neutral analytes over a distance longer than 10 m was demonstrated, without either significant signal loss or serious delay of signal response. The limit of detection for these explosives in the study was in the range of ca. 59-842 fg (S/N = 3, n = 8) on various surfaces. Acceptable relative standard deviation (RSD) values (ca. 4.6-10.2%, n = 8) were obtained for all the surfaces tested, showing the successful sampling of trace non-volatile explosive compounds (sub-picogram) by the GIND device for the EESI mass spectrometric analysis.

  3. Highly Sensitive Local Surface Plasmon Resonance in Anisotropic Au Nanoparticles Deposited on Nanofibers

    Directory of Open Access Journals (Sweden)

    Masanari Saigusa

    2015-01-01

    Full Text Available This paper reports the facile and high-throughput fabrication method of anisotropic Au nanoparticles with a highly sensitive local surface plasmon resonance (LPR using cylindrical nanofibers as substrates. The substrates consisting of nanofibers were prepared by the electrospinning of poly(vinylidene fluoride (PVDF. The Au nanoparticles were deposited on the surface of electrospun nanofibers by vacuum evaporation. Scanning electron microscopy revealed the formation of a curved Au island structure on the surface of cylindrical nanofibers. Polarized UV-visible extinction spectroscopy showed anisotropy in their LPR arising from the high surface curvature of the nanofiber. The LPR of the Au nanoparticles on the thinnest nanofiber with a diameter of ~100 nm showed maximum refractive index (RI sensitivity over 500 nm/RI unit (RIU. The close correlation between the fiber diameter dependence of the RI sensitivity and polarization dependence of the LPR suggests that anisotropic Au nanoparticles improve RI sensitivity.

  4. The effect of material composition of 3-dimensional graphene oxide and self-doped polyaniline nanocomposites on DNA analytical sensitivity.

    Science.gov (United States)

    Yang, Tao; Chen, Huaiyin; Yang, Ruirui; Wang, Xinxing; Nan, Fuxin; Jiao, Kui

    2015-09-01

    Until now, morphology effects of 2-dimensional or 3-dimensional graphene nanocomposites and the effect of material composition on the biosensors have been rarely reported. In this paper, the various nanocomposites based on graphene oxide and self-doped polyaniline nanofibres for studying the effect of morphology and material composition on DNA sensitivity were directly reported. The isolation and dispersion of graphene oxide were realized via intercalated self-doped polyaniline and ultrasonication, where the ultrasonication prompts the aggregates of graphite oxide to break up and self-doped polyaniline to diffuse into the stacked graphene oxide. Significant electrochemical enhancement has been observed due to the existence of self-doped polyaniline, which bridges the defects for electron transfer and, in the mean time, increases the basal spacing between graphene oxide sheets. Different morphologies can result in different ssDNA surface density, which can further influence the hybridization efficiency. Compared with 2-dimensional graphene oxide, self-doped polyaniline and other morphologies of nanocomposites, 3-dimensional graphene oxide-self-doped polyaniline nanowalls exhibited the highest surface density and hybridization efficiency. Furthermore, the fabricated biosensors presented the broad detection range with the low detection limit due to the specific surface area, a large number of electroactive species, and open accessible space supported by nanowalls.

  5. Sensitivity Dependence of Surface Plasmon Resonance Based Sensors on Prism Refractive Index

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    We theoretically and experimentally demonstrate that refractive index of the prism used toload metal film has significant influence on sensitivity of surface plasmon resonance based sensors. Theprism with lower refractive index gives the sensors a higher sensitivity in detecting refractive index varia-tions of a sample. We attribute this effect to the fact that a prism with low refractive index will increasecoupling distance between surface plasmons and the medium under investigation.

  6. In-vacuum scattered light reduction with cupric oxide surfaces for sensitive fluorescence detection

    CERN Document Server

    Norrgard, Eric B; Barry, John F; McCarron, Daniel J; Steinecker, Matthew H; DeMille, David

    2016-01-01

    We demonstrate a simple and easy method for producing low-reflectivity surfaces that are ultra-high vacuum compatible, may be baked to high temperatures, and are easily applied even on complex surface geometries. Black cupric oxide (CuO) surfaces are chemically grown in minutes on any copper surface, allowing for low-cost, rapid prototyping and production. The reflective properties are measured to be comparable to commercially available products for creating optically black surfaces. We describe a vacuum apparatus which uses multiple blackened copper surfaces for sensitive, low-background detection of molecules using laser-induced fluorescence.

  7. Highly sensitive surface plasmon resonance chemical sensor based on Goos-Hanchen effects

    Science.gov (United States)

    Yin, Xiaobo; Hesselink, Lambertus

    2006-08-01

    The resonance enhanced Goos-Hanchen shifts at attenuated total internal reflection enables the possibility for highly sensitive surface plasmon resonance sensor. The observed giant displacements result from the singular phase retardation at the resonance where the phase is continuous but changes dramatically. The phenomenon is proposed for chemical sensing and the superior sensitivity is demonstrated.

  8. ZnO sensing film thickness effects on the sensitivity of surface plasmon resonance sensors with angular interrogation

    Energy Technology Data Exchange (ETDEWEB)

    Bao Ming; Li Ge; Jiang Dongmei; Cheng Wenjuan [State Key Laboratory of Precision Spectroscopy, and Department of Physics, East China Normal University, Shanghai 200062 (China); Ma Xueming, E-mail: xmma@phy.ecnu.edu.cn [State Key Laboratory of Precision Spectroscopy, and Department of Physics, East China Normal University, Shanghai 200062 (China)

    2010-07-25

    The effects of ZnO sensing film thickness on the surface plasmon resonance (SPR) curve have been investigated. ZnO sensing films with the thickness of 20 nm, 30 nm, 200 nm, 220 nm and 240 nm have been deposited onto Ag/glass substrates by radio frequency magnetron (RF) sputtering and thermally treated at 300 deg. C in air for 1 h. The surface morphology of the sample was inspected using an atomic force microscope (AFM). The refractive index of the ZnO films was extracted by using spectroscopic ellipsometry (SE). Theoretical analysis of the sensitivity of the SPR sensors with different ZnO sensing film thickness is discussed, and the experimental results are in agreement with the calculated value. Also, the theoretical calculation of the effects of ZnO film thickness on the SPR curves in the presence of different analytes are presented and studied. It is demonstrated that SPR sensors with angular interrogation may attain higher sensitivity and can detect higher surface environment refractive index with proper ZnO sensing film thickness.

  9. Surface enhanced Raman optical activity as an ultra sensitive tool for ligand binding analysis

    DEFF Research Database (Denmark)

    Johannessen, Christian; Abdali, Salim

    2007-01-01

    The Surface Enhanced Resonance Raman Scattering (SERRS) and Surface Enhanced Resonance Raman Optical Activity (SERROA) spectra of myoglobin and the myoglobin-azide complex were measured on very dilute samples (100 nM protein) in order to analyze the sensitivity of SERROA spectroscopy when inducing...

  10. Imaging of surface plasmon polariton interference using phase-sensitive scanning tunneling microscope

    NARCIS (Netherlands)

    Jose, J.; Segerink, Franciscus B.; Korterik, Jeroen P.; Herek, Jennifer Lynn; Offerhaus, Herman L.

    2011-01-01

    We report the surface plasmon polariton interference, generated via a ‘buried’ gold grating, and imaged using a phase-sensitive Photon Scanning Tunneling Microscope (PSTM). The phase-resolved PSTM measurement unravels the complex surface plasmon polariton interference fields at the gold-air

  11. Sensitive method for detection of cocaine and associated analytes by liquid chromatography-tandem mass spectrometry in urine.

    Science.gov (United States)

    Langman, Loralie J; Bjergum, Matthew W; Williamson, Christopher L; Crow, Frank W

    2009-10-01

    Cocaine (COC) is a potent CNS stimulant that is metabolized to benzoylecgonine (BE) and further metabolized to minor metabolites such as m-hydroxybenzoylecgonine (m-HOBE). COC is also metabolized to norcocaine (NC). Cocaethylene (CE) is formed when cocaine and ethyl alcohol are used simultaneously. Anhydroecgonine methyl ester (AEME) is a unique marker following smoked cocaine, and anhydroecgonine ethyl ester (AEEE) is found in cocaine smokers who also use ethyl alcohol. We developed a liquid chromatography-tandem mass spectrometry (LC-MS-MS) method for the detection and quantitation of COC, BE, NC, CE, m-HOBE, AEME, and AEEE in urine. Two hundred samples previously analyzed by gas chromatography (GC) coupled with MS were extracted using solid-phase extraction. Chromatographic separation was achieved using a gradient consisting of mobile phase A [20 mM ammonium formate (pH 2.7)] and mobile phase B (methanol/acetonitrile, 50:50), an XDB-C(8) (50 x 2.1 mm, 1.8 microm) column and a flow rate of 270 microL/min. Concentrations were calculated by comparing the peak-area with the internal standard and plotted against a standard curve. The assay displayed linearity from 1.0 to 100 ng/mL. Within- and between-run coefficients of variation were < 10% throughout the linear range. A method comparison between GC-MS and LC-MS-MS showed good correlation for COC (r(2) = 0.982) and BE (r(2) = 0.955). We report here on a sensitive method to identify clinically and forensically relevant cocaine and associated analytes at concentrations as low as 1.0 ng/mL.

  12. Analytical model of surface uplift above axisymmetric flat-lying magma intrusions: Implications for sill emplacement and geodesy

    OpenAIRE

    Galland, Olivier; Scheibert, Julien

    2013-01-01

    58 pages, 17 figures, 2 tables. Accepted in Journal of Volcanology and Geothermal Research; International audience; In this paper, we develop a new axisymmetric analytic model of surface uplift upon sills and laccoliths, based on the formulation of a thin bending plate lying on an elastic foundation. In contrast to most former models also based on thin bending plate formulation, our model accounts for (i) axi-symmetrical uplift, (ii) both upon and outside the intrusion. The model accounts for...

  13. Surface conductivity in electrokinetic systems with porous and charged interfaces: Analytical approximations and numerical results.

    Science.gov (United States)

    Barbati, Alexander C; Kirby, Brian J

    2016-07-01

    We derive an approximate analytical representation of the conductivity for a 1D system with porous and charged layers grafted onto parallel plates. Our theory improves on prior work by developing approximate analytical expressions applicable over an arbitrary range of potentials, both large and small as compared to the thermal voltage (RTF). Further, we describe these results in a framework of simplifying nondimensional parameters, indicating the relative dominance of various physicochemical processes. We demonstrate the efficacy of our approximate expression with comparisons to numerical representations of the exact analytical conductivity. Finally, we utilize this conductivity expression, in concert with other components of the electrokinetic coupling matrix, to describe the streaming potential and electroviscous effect in systems with porous and charged layers.

  14. THE EFFECT OF BONDING AND SURFACE SEALANT APPLICATION ON POSTOPERATIVE SENSITIVITY FROM POSTERIOR COMPOSITES

    Directory of Open Access Journals (Sweden)

    Neslihan TEKÇE

    2015-10-01

    Full Text Available Purpose: The purpose of the study was to evaluate the postoperative sensitivity of posterior Class I composite restoration at short-term, restorated with two different all-in-one self-etch adhesives with or without surface sealant application. Materials and Methods: 44 restorations were inserted in 11 patients who required Class I restorations in their molars. Each patient received 4 restorations, thus four groups were formed; (1 G-Aenial Bond (GC, Japan; (2 Clearfil S3 Bond (Kuraray, Japan; (3 G-Aenial Bond+Fortify Plus (Bisco, USA, (4 Clearfil S3 Bond+Fortify Plus. Sensitivity was evaluated at 24h, 7, 15, and 30 days using cold air, ice, and pressure stimuli using a visual analog scale. Comparisons of continuous variables between the sensitivity evaluations were performed using the Friedman’s One-Way Analysis of Variance with repeated measures test (p0.05. The use of Clearfil S3 Bond resulted in almost the same level of postoperative sensitivity as did the use of G-Aenial Bond. The highest sensitivity scores were observed for the surface sealant applied teeth without any statistical significance (p>0.05. Conclusions: Self etch adhesives displayed postoperative sensitivity. The sensitivity scores slightly decreased at the end of 30 days (p>0.05. Surface sealant application did not result in a decrease in sensitivity scores for either dentin adhesives.

  15. Silanization of inner surfaces of nanoelectrospray ionization emitters for reduced analyte adsorption.

    Science.gov (United States)

    Choi, Yong Seok; Wood, Troy D

    2008-04-01

    During the course of nanoelectrospray ionization (nanoESI) of substance P, an unusual type of signal reduction was observed with flow rates silanized. Emitters treated with hexamethyldisilazane or 3-aminopropyltriethoxysilane showed higher analyte signals for substance P than untreated emitters, suggesting a reduction of analyte adsorption onto the inner walls of silanized emitters. The efficacy of reduced peptide adsorption was demonstrated for emitters silanized with 3-aminopropyltriethoxysilane using a simple peptide mixture as well as a more complex peptide mixture (a tryptic digest of horse hemoglobin).

  16. Synthesis and processing of ELISA polymer substitute: The influence of surface chemistry and morphology on detection sensitivity

    Science.gov (United States)

    Hosseini, Samira; Ibrahim, Fatimah; Djordjevic, Ivan; Rothan, Hussin A.; Yusof, Rohana; van der Marel, Cees; Koole, Leo H.

    2014-10-01

    Despite the known drawbacks of enzyme-linked immunosorbent assay (ELISA), one of the deficiencies that have relatively been ignored is the performance of ELISA substrate itself. Polystyrene (PS), as the cost effective material of choice for mass production of ELISA well-plates, has shown obvious lacks of suitable physical and chemical properties for protein attachment. The general concept of this work was to develop a potential substrate that can be suggested as a material of choice for production of a new generation of ELISA analytical kits. Spin-coated thin films of polymethyl methacrylate-co-methacrylic acid (PMMA-co-MAA) on silicon surfaces were designed and processed for detection of dengue virus. Coated surfaces of different molar ratios have been investigated as carboxyl-functionalized layers for obtaining platform for biomolecule immobilization with high level of protein activity. To improve the sensitivity of detection, we have used amine functional "spacers", hexamethylenediamine (HMDA) and polyethyleneimine (PEI), which were covalently bonded to the surfaces of PMMA-co-MAA coatings. Results demonstrate that the variation of surface concentration of carboxyl groups of PMMA-co-MAA can be used to control the amine surface concentration after carbodiimide coupling with HMDA and PEI spacers. The presence of amine spacers increases hydrophilicity of the coatings and significantly impacts the polymer surface morphology. In particular, protein immobilization via amine-bearing spacers has been achieved in two effective steps: (1) carbodiimide bonding between amine spacer molecules and PMMA-co-MAA polymer coatings; and (2) covalent immobilization of antibody via glutaraldehyde reaction with amine groups from amine-treated surfaces. The application of PEI spacer in comparison to HMDA has shown much higher intensity of detection signal in ELISA experiment, indicating better immobilization efficiency and preservation of antibody activity upon attachment to the

  17. Improved analytic methods for coal surface area and pore size distribution determination using 77 K nitrogen adsorption experiment

    Institute of Scientific and Technical Information of China (English)

    Wang Gongda; Wang Kai; Ren Tingxiang

    2014-01-01

    77 K nitrogen adsorption was the most widely used technique for determining surface area and pore size distribution of coal. Brunauer-Emmett-Teller (BET) and Barrett-Joyner-Halenda (BJH) model are com-monly used analytic methods for adsorption/desorption isotherm. A Chinese anthracite coal is tested in this study using an improved experimental method and adsorption isotherm analyzed by three adsorp-tion mechanisms at different relative pressure stages. The result shows that the micropore filling adsorp-tion predominates at the relative pressure stage from 6.8E?7 to 9E?3. Theoretically, BET and BJH model are not appropriate for analyzing coal samples which contain micropores. Two new analytic procedures for coal surface area and pore size distribution calculation are developed in this work. The results show that BET model underestimates surface area, and micropores smaller than 1.751 nm account for 35.5%of the total pore volume and 74.2%of the total surface area. The investigation of surface area and pore size distribution by incorporating the influence of micropore is significant for understanding adsorption mechanism of methane and carbon dioxide in coal.

  18. Sensitivity of Greenland Ice Sheet surface mass balance to surface albedo parameterization: a study with a regional climate model

    NARCIS (Netherlands)

    van Angelen, J.H.; Lenaerts, J.T.M.; Lhermitte, S.; Fettweis, X.; Kuipers Munneke, P.; van den Broeke, M.R.; van Meijgaard, E.; Smeets, C.J.P.P.

    2012-01-01

    We present a sensitivity study of the surface mass balance (SMB) of the Greenland Ice Sheet, as modeled using a regional atmospheric climate model, to various parameter settings in the albedo scheme. The snow albedo scheme uses grain size as a prognostic variable and further depends on cloud cover,

  19. Surface modification of copolymerized films from three-armed biodegradable macromers - An analytical platform for modified tissue engineering scaffolds.

    Science.gov (United States)

    Müller, Benno M; Loth, Rudi; Hoffmeister, Peter-Georg; Zühl, Friederike; Kalbitzer, Liv; Hacker, Michael C; Schulz-Siegmund, Michaela

    2017-03-15

    The concept of macromers allows for a broad adjustment of biomaterial properties by macromer chemistry or copolymerization. Copolymerization strategies can also be used to introduce reactive sites for subsequent surface modification. Control over surface features enables adjustment of cellular reactions with regard to site and object of implantation. We designed macromer-derived polymer films which function as non-implantable analytical substrates for the investigation of surface properties of equally composed scaffolds for bone tissue engineering. To this end, a toolbox of nine different biodegradable, three-armed macromers was thermally cross-copolymerized with poly(ethylene glycol)-methacrylate (PEG-MA) to films. Subsequent activation of PEG-hydroxyl groups with succinic anhydride and N-hydroxysuccinimid allowed for covalent surface modification. We quantified the capacity to immobilize analytes of low (amino-functionalized fluorescent dye, Fcad, and RGD-peptides) and high (alkaline phosphatase, ALP) molecular weight. Fcad grafting level was controlled by macromer chemistry, content and molecular weight of PEG-MA, but also the solvent used for film synthesis. Fcad molar amount per surface area was twentyfive times higher on high-swelling compared to low-swelling films, but differences became smaller when large ALP (appr. 2:1) were employed. Similarly, small differences were observed on RGD peptide functionalized films that were investigated by cell adhesion studies. Presentation of PEG-derivatives on surfaces was visualized by atomic force microscopy (AFM) which unraveled composition-dependent domain formation influencing fluorescent dye immobilization. Surface wetting characteristics were investigated via static water contact angle. We conclude that macromer ethoxylation and lactic acid content determined film swelling, PEG domain formation and eventually efficiency of surface decoration.

  20. Structural sensitivity studies of ethylene hydrogenation on platinum and rhodium surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Quinlan, M.A. [California Univ., Berkeley, CA (United States). Dept. of Chemistry]|[Lawrence Berkeley National Lab., CA (United States)

    1996-01-01

    The catalytic hydrogenation of ethylene and hydrogen on the well characterized surfaces of the noble metals platinum and rhodium has been studied for the purposes of determining the relative activity of these two substrates as well as the degree of structure sensitivity. The Pt(111) and the Rh(755) single crystal surfaces,as well as Pt and Rh foils, were employed as substrates to study the effect of surface step structure on reactivity. In addition, vibrational spectroscopy studies were performed for ethylene adsorption on the stepped Rh(755) surface. The catalytic reaction were obtained using a combined ultrahigh vacuum chamber coupled with an atmospheric pressure reaction chamber that functioned as a batch reactor. Samples could be prepared using standard surface science techniques and characterized for surface composition and geometry using Auger Electron Spectroscopy and Low Energy Electron Diffraction. A comparison of the reactivity of Rh(111) with the results from this study on Rh(755) allows a direct determination of the effect of step structure on ethylene hydrogenation activity. Structure sensitivity is expected to exhibit orders of magnitude differences in rate as surface orientation is varied. In this case, no significant differences were found, confirming the structure insensitivity of this reaction over this metal. The turnover frequency of the Rh(111) surface, 5 {times} 10{sup 1} s{sup {minus}1}, is in relatively good agreement with the turnover frequency of 9 {times} 10{sup 1} s{sup {minus}1} measured for the Rh(755) surface. Rate measurements made on the Pt(111) surface and the Pt foil are in excellent agreement, both measuring 3 {times} 10{sup 2} s{sup minus}1. Likewise, it is concluded that no strong structure sensitivity for the platinum surfaces exists. High Resolution Electron Energy Loss Spectroscopy studies of adsorbed ethylene on the Rh(755) surface compare favorably with the ethylidyne spectra obtained on the Rh(111) and Rh(100) surfaces.

  1. One-dimensional model of interacting-step fluctuations on vicinal surfaces: Analytical formulas and kinetic Monte Carlo simulations

    Science.gov (United States)

    Patrone, Paul N.; Einstein, T. L.; Margetis, Dionisios

    2010-12-01

    We study analytically and numerically a one-dimensional model of interacting line defects (steps) fluctuating on a vicinal crystal. Our goal is to formulate and validate analytical techniques for approximately solving systems of coupled nonlinear stochastic differential equations (SDEs) governing fluctuations in surface motion. In our analytical approach, the starting point is the Burton-Cabrera-Frank (BCF) model by which step motion is driven by diffusion of adsorbed atoms on terraces and atom attachment-detachment at steps. The step energy accounts for entropic and nearest-neighbor elastic-dipole interactions. By including Gaussian white noise to the equations of motion for terrace widths, we formulate large systems of SDEs under different choices of diffusion coefficients for the noise. We simplify this description via (i) perturbation theory and linearization of the step interactions and, alternatively, (ii) a mean-field (MF) approximation whereby widths of adjacent terraces are replaced by a self-consistent field but nonlinearities in step interactions are retained. We derive simplified formulas for the time-dependent terrace-width distribution (TWD) and its steady-state limit. Our MF analytical predictions for the TWD compare favorably with kinetic Monte Carlo simulations under the addition of a suitably conservative white noise in the BCF equations.

  2. Surface analytical studies of maxillofacial implants: influence of the preoperational treatment and the human body on the surface properties of retrieved implants.

    Science.gov (United States)

    Kiss, Gábor; Sebők, Béla; Szabó, Péter J; Joób, Arpád F; Szabó, György

    2014-05-01

    In the present work, surface analytical investigation of unimplanted as well as retrieved pyrolytic carbon-covered carbon/carbon composite implants and Ti osteosynthesis plates is reported. The Ti plates were covered by a 200-nm-thick, anodically and thermally formed TiO2 layer. Our results suggest that although the oxide layer on the Ti miniplates remained stable during the time spent in the human body, there is still material transport between the implant and the human body. In case of the carbon/carbon composite implants, damage of the carbon fibers constituting the material was found on one side of the sterile implant and attributed to the manufacturing process. The NaCl crystals originally present on the surface of the sterile material disappeared during the time spent in the human body. As a result of the interaction with the human body, a new surface layer (mainly constituted of carbon) appeared on the implant. The results indicate that both the time spent in the human organism and the preparation of the implants before operation can have detectable effects on the investigated surface properties. Surface analytical investigations could therefore provide information not only about the biocompatibility of these materials but also about the effect of their treatment before operation.

  3. An analytical inversion method for determining regional and global emissions of greenhouse gases: Sensitivity studies and application to halocarbons

    Directory of Open Access Journals (Sweden)

    A. Stohl

    2009-03-01

    Full Text Available A new analytical inversion method has been developed to determine the regional and global emissions of long-lived atmospheric trace gases. It exploits in situ measurement data from three global networks and builds on backward simulations with a Lagrangian particle dispersion model. The emission information is extracted from the observed concentration increases over a baseline that is itself objectively determined by the inversion algorithm. The method was applied to two hydrofluorocarbons (HFC-134a, HFC-152a and a hydrochlorofluorocarbon (HCFC-22 for the period January 2005 until March 2007. Detailed sensitivity studies with synthetic as well as with real measurement data were done to quantify the influence on the results of the a priori emissions and their uncertainties as well as of the observation and model errors. It was found that the global a posteriori emissions of HFC-134a, HFC-152a and HCFC-22 all increased from 2005 to 2006. Large increases (21%, 16%, 18%, respectively from 2005 to 2006 were found for China, whereas the emission changes in North America (−9%, 23%, 17%, respectively and Europe (11%, 11%, −4%, respectively were mostly smaller and less systematic. For Europe, the a posteriori emissions of HFC-134a and HFC-152a were slightly higher than the a priori emissions reported to the United Nations Framework Convention on Climate Change (UNFCCC. For HCFC-22, the a posteriori emissions for Europe were substantially (by almost a factor 2 higher than the a priori emissions used, which were based on HCFC consumption data reported to the United Nations Environment Programme (UNEP. Combined with the reported strongly decreasing HCFC consumption in Europe, this suggests a substantial time lag between the reported time of the HCFC-22 consumption and the actual time of the HCFC-22 emission. Conversely, in China where HCFC consumption is increasing rapidly according to the UNEP data, the a posteriori emissions are only about 40% of the a

  4. Design optimization of highly sensitive LSPR enhanced surface plasmon resonance biosensors with nanoholes

    Institute of Scientific and Technical Information of China (English)

    Bin Wu; Qingkang Wang

    2008-01-01

    For breaking through the sensitivity limitation of conventional surface plasmon resonance (SPR) biosensors, novel highly sensitive SPR biosensors with Au nanoparticles and nanogratings enhancement have been proposed recently.But in practice, these structures have obvious disadvantages.In this study, a nanohole based sensitivity enhancement SPR biosensor is proposed and the influence of different structural parameters on the performance is investigated by using rigorous coupled wave analysis (RCWA).Electromagnetic field distributions around the nanohole are also given out to directly explain the performance difference for various structural parameters.The results indicate that significant sensitivity increase is associated with localized surface plasmons (LSPs) excitation mediated by nanoholes.Except to outcome the weakness of other LSP based biosensors, larger resonance angle shift, reflectance amplitude, and sharper SPR curves' width are obtained simultaneously under optimized structural parameters.

  5. Analytical calculation of electron group velocity surfaces in uniform strained graphene

    Science.gov (United States)

    Gómez-Arias, Wilfrido A.; Naumis, Gerardo G.

    2016-12-01

    Electron group velocity for graphene under uniform strain is obtained analytically by using the tight-binding (TB) approximation. Such closed analytical expressions are useful in order to calculate the electronic, thermal and optical properties of strained graphene. These results allow to understand the behavior of electrons when graphene is subjected to strong strain and nonlinear corrections, for which the usual Dirac approach is no longer valid. Some particular cases of uniaxial and shear strain were analyzed. The evolution of the electron group velocity indicates a break-up of the trigonal warping symmetry, which is replaced by a warping consistent with the symmetry of the strained reciprocal lattice. To do this, analytical expressions for the shape of the first Brillouin zone (BZ) of the honeycomb strained reciprocal lattice are provided. Finally, the Fermi velocity becomes strongly anisotropic, i.e., for a strong pure shear strain (20% of the lattice parameter), the two inequivalent Dirac cones merge and the Fermi velocity is zero in one of the principal axis of deformation. We found that nonlinear terms are essential to describe the effects of deformation for electrons near or at the Fermi energy.

  6. Electron band bending and surface sensitivity: X-ray photoelectron spectroscopy of polar GaN surfaces

    Science.gov (United States)

    Bartoš, I.; Romanyuk, O.; Paskova, T.; Jiříček, P.

    2017-10-01

    The role of electron band bending and surface sensitivity in determining the core level binding energies by X-ray photoelectron spectroscopy is investigated. A dominating contribution of surface atomic layers to photoemission intensity is confirmed for normal photoemission. The energy of the photoelectron core level peak does not deviate from core level peak energies of electrons photoemitted from the surface atomic layers of the crystal. The higher surface sensitivity regime, achieved e.g. at off-normal photoelectron detection angle, can be used to study the surface potential barrier in just a few topmost atomic layers. In addition, it is demonstrated that core level binding energy measured by angle-resolved X-ray photoelectron spectroscopy reflect the electron attenuation anisotropy. In particular, core level binding energy changes with emission angle and correlates with the forward focusing directions in a crystal. This effect is demonstrated by measuring the polar angle dependence of Ga 3d core levels on clean GaN(0001) and GaN(000 1 bar) surfaces with a higher and a lower band bending, respectively. The effect is explained by variation of emission depth in a crystal for normal and off-normal photoelectron emission angles.

  7. Surface plasmon resonance hydrogen sensor based on metallic grating with high sensitivity.

    Science.gov (United States)

    Lin, Kaiqun; Lu, Yonghua; Chen, Junxue; Zheng, Rongsheng; Wang, Pei; Ming, Hai

    2008-11-10

    High sensitivity is obtained at larger resonant incident angle if negative diffraction order of metallic grating is used to excite the surface plasmon. A highly sensitive grating-based surface plasmon resonance (SPR) sensor is designed for the hydrogen detection. A thin palladium (Pd) film deposited on the grating surface is used as transducer. The influences of grating period and the thickness of Pd on the performance of sensor are investigated using rigorous coupled-wave analysis (RCWA) method. The sensitivity as well as the width of the SPR curves and reflective amplitude is considered simultaneously for designing the grating-based SPR hydrogen sensor, and a set of optimized structural parameters is presented. The performance of grating-based SPR sensor is also compared with that of conventional prism-based SPR sensor.

  8. Zero-D sensitivity studies with the NCAR CCM land surface parameterization scheme

    Science.gov (United States)

    Henderson-Sellers, A.; Wilson, M. F.; Dickinson, R. E.

    1986-05-01

    The boundary package of a version of the NCAR Community Climate Model was run as a stand alone zero-dimensional model. Soil data and a soil parameterization scheme were added to the vegetation parameterization. Sensitivity experiments, including conditions representative of a low latitude evergreen forest, a sand desert, a high latitude coniferous forest, high latitude tundra, and prairie grassland were undertaken. The land surface scheme shows the greatest sensitivity to soil texture variation, particularly to changes in hydraulic conductivity and diffusivity.

  9. Mass Sensitivity Optimization of a Surface Acoustic Wave Sensor Incorporating a Resonator Configuration

    OpenAIRE

    Wenchang Hao; Jiuling Liu; Minghua Liu; Yong Liang; Shitang He

    2016-01-01

    The effect of the sensitive area of the two-port resonator configuration on the mass sensitivity of a Rayleigh surface acoustic wave (R-SAW) sensor was investigated theoretically, and verified in experiments. A theoretical model utilizing a 3-dimensional finite element method (FEM) approach was established to extract the coupling-of-modes (COM) parameters in the absence and presence of mass loading covering the electrode structures. The COM model was used to simulate the frequency response of...

  10. Analytic computation on the forcible thawing temperature field formed by a single heat transfer pipe with unsteady outer surface temperature

    Institute of Scientific and Technical Information of China (English)

    ZHANG Chi; YANG Wei-hao; QI Jia-gen; ZHANG Tao

    2012-01-01

    A comprehensive and systematic research on the forcible thawing temperature field formed by a single heat transfer pipe with unsteady outer surface temperature was carried out by analytic computation according to the theory of similitude.The distribution law of thawing temperature field,calculation formulas of thawing radius b,heat flux density q and average thawing temperature (T) were obtained.It theoretically explains that the main influential factors of thawing radius b,heat flux density q and thawing average temperature (T) are K,f,Lλ and ω(f),but Lc affects little.Finally,based on the forcible thawing project of Hulusu air shaft lining,the field data indicate that the analytical formulas of this article are comparatively accurate.

  11. A self-starting method for obtaining analytic potential-energy surfaces from ab initio electronic structure calculations.

    Science.gov (United States)

    Agrawal, P M; Malshe, M; Narulkar, R; Raff, L M; Hagan, M; Bukkapatnum, S; Komanduri, R

    2009-02-05

    Previous methods proposed for obtaining analytic potential-energy surfaces (PES) from ab initio electronic structure calculations are not self-starting. They generally require that the sampling of configuration space important in the reaction dynamics of the process being investigated be initiated by using chemical intuition or a previously developed semiempirical potential-energy surface. When the system under investigation contains four or more atoms undergoing three- and four-center reactions in addition to bond scission processes, obtaining a sufficiently converged initial sampling can be very difficult due to the extremely large volume of configuration space that is important in the reaction dynamics. It is shown that by combining direct dynamics (DD) with previously reported molecular dynamics (MD), novelty sampling (NS), and neural network (NN) methods, an analytical surface suitable for MD computations for large systems may be obtained. Application of the method to the investigation of N-O bond scission and cis-trans isomerization reactions of HONO followed by comparison of the resulting neural network potential-energy surface to one obtained by using a semiempirical potential to initiate the sampling shows that the two potential surfaces are the same within the fitting accuracy of the surfaces. It is concluded that the combination of direct dynamics, molecular dynamics, novelty sampling, and neural network fitting provides a self-starting, robust, and accurate DD/MD/NS/NN method for the execution of first-principles, ab initio, molecular dynamics studies in systems containing four or more atoms which are undergoing simultaneous two-, three-, and four-center reactions.

  12. Mass Sensitivity Optimization of a Surface Acoustic Wave Sensor Incorporating a Resonator Configuration

    Directory of Open Access Journals (Sweden)

    Wenchang Hao

    2016-04-01

    Full Text Available The effect of the sensitive area of the two-port resonator configuration on the mass sensitivity of a Rayleigh surface acoustic wave (R-SAW sensor was investigated theoretically, and verified in experiments. A theoretical model utilizing a 3-dimensional finite element method (FEM approach was established to extract the coupling-of-modes (COM parameters in the absence and presence of mass loading covering the electrode structures. The COM model was used to simulate the frequency response of an R-SAW resonator by a P-matrix cascading technique. Cascading the P-matrixes of unloaded areas with mass loaded areas, the sensitivity for different sensitive areas was obtained by analyzing the frequency shift. The performance of the sensitivity analysis was confirmed by the measured responses from the silicon dioxide (SiO2 deposited on different sensitive areas of R-SAW resonators. It is shown that the mass sensitivity varies strongly for different sensitive areas, and the optimal sensitive area lies towards the center of the device.

  13. Mass Sensitivity Optimization of a Surface Acoustic Wave Sensor Incorporating a Resonator Configuration.

    Science.gov (United States)

    Hao, Wenchang; Liu, Jiuling; Liu, Minghua; Liang, Yong; He, Shitang

    2016-04-20

    The effect of the sensitive area of the two-port resonator configuration on the mass sensitivity of a Rayleigh surface acoustic wave (R-SAW) sensor was investigated theoretically, and verified in experiments. A theoretical model utilizing a 3-dimensional finite element method (FEM) approach was established to extract the coupling-of-modes (COM) parameters in the absence and presence of mass loading covering the electrode structures. The COM model was used to simulate the frequency response of an R-SAW resonator by a P-matrix cascading technique. Cascading the P-matrixes of unloaded areas with mass loaded areas, the sensitivity for different sensitive areas was obtained by analyzing the frequency shift. The performance of the sensitivity analysis was confirmed by the measured responses from the silicon dioxide (SiO₂) deposited on different sensitive areas of R-SAW resonators. It is shown that the mass sensitivity varies strongly for different sensitive areas, and the optimal sensitive area lies towards the center of the device.

  14. Forty-Four Pass Fibre Optic Loop for Improving the Sensitivity of Surface Plasmon Resonance Sensors

    CERN Document Server

    Su, Chin B

    2007-01-01

    A forty-four pass fibre optic surface plasmon resonance sensor that enhances detection sensitivity according to the number of passes is demonstrated for the first time. The technique employs a fibre optic recirculation loop that passes the detection spot forty- four times, thus enhancing sensitivity by a factor of forty-four. Presently, the total number of passes is limited by the onset of lasing action of the recirculation loop. This technique offers a significant sensitivity improvement for various types of plasmon resonance sensors that may be used in chemical and biomolecule detections.

  15. The pH-dependant attachment of ceria nanoparticles to silica using surface analytical techniques

    Energy Technology Data Exchange (ETDEWEB)

    Dawkins, K.; Rudyk, B.W.; Xu, Z.; Cadien, K., E-mail: kcadien@ualberta.ca

    2015-08-01

    Graphical abstract: - Highlights: • A model for interaction between ceria nanoparticles and silica surfaces is proposed. • Proposed model investigated using zeta potential measurements and XPS. • Surface contamination is minimized at higher slurry pH levels. • High-resolution Ce 3d XPS and surface composition measured at different pH levels. • Variations in ceria contamination on silica surfaces via SEM and AES are studied. - Abstract: The adhesion and removal of ceria particles to a silica surface was investigated with the use of X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and auger electron spectroscopy (AES) measurements. A model is presented based on electrophoretic mobility measurements of ceria slurry and silica particles at different pH's. XPS results show that at acidic pH values, ceria is present on silica surfaces, but at alkaline pH values, far less ceria is present, or no ceria is present in the extreme case. SEM results corroborated the XPS results showing uniform distribution of ceria particles on silica surface at pH 6 while a clean silica surface is observed at pH 12. However, SEM images show agglomeration of ceria particles occurring at the isoelectric point of ceria at ∼pH 9.6. High resolution Ce 3d XPS analysis indicates that ceria present on the surface is composed ∼31% Ce(III) and ∼69% Ce(IV). AES mapping done at specific points on the silica surface validated both XPS and SEM results. Based on XPS, SEM and AES analyses, it is clear that an alkaline pH is necessary to minimize particulate contamination of silica surface by ceria.

  16. Investigation into Mass Loading Sensitivity of Sezawa Wave Mode-Based Surface Acoustic Wave Sensors

    Directory of Open Access Journals (Sweden)

    N. Ramakrishnan

    2013-02-01

    Full Text Available In this work mass loading sensitivity of a Sezawa wave mode based surface acoustic wave (SAW device is investigated through finite element method (FEM simulation and the prospects of these devices to function as highly sensitive SAW sensors is reported. A ZnO/Si layered SAW resonator is considered for the simulation study. Initially the occurrence of Sezawa wave mode and displacement amplitude of the Rayleigh and Sezawa wave mode is studied for lower ZnO film thickness. Further, a thin film made of an arbitrary material is coated over the ZnO surface and the resonance frequency shift caused by mass loading of the film is estimated. It was observed that Sezawa wave mode shows significant sensitivity to change in mass loading and has higher sensitivity (eight times higher than Rayleigh wave mode for the same device configuration. Further, the mass loading sensitivity was observed to be greater for a low ZnO film thickness to wavelength ratio. Accordingly, highly sensitive SAW sensors can be developed by coating a sensing medium over a layered SAW device and operating at Sezawa mode resonance frequency. The sensitivity can be increased by tuning the ZnO film thickness to wavelength ratio.

  17. Investigation into mass loading sensitivity of sezawa wave mode-based surface acoustic wave sensors.

    Science.gov (United States)

    Mohanan, Ajay Achath; Islam, Md Shabiul; Ali, Sawal Hamid; Parthiban, R; Ramakrishnan, N

    2013-02-06

    In this work mass loading sensitivity of a Sezawa wave mode based surface acoustic wave (SAW) device is investigated through finite element method (FEM) simulation and the prospects of these devices to function as highly sensitive SAW sensors is reported. A ZnO/Si layered SAW resonator is considered for the simulation study. Initially the occurrence of Sezawa wave mode and displacement amplitude of the Rayleigh and Sezawa wave mode is studied for lower ZnO film thickness. Further, a thin film made of an arbitrary material is coated over the ZnO surface and the resonance frequency shift caused by mass loading of the film is estimated. It was observed that Sezawa wave mode shows significant sensitivity to change in mass loading and has higher sensitivity (eight times higher) than Rayleigh wave mode for the same device configuration. Further, the mass loading sensitivity was observed to be greater for a low ZnO film thickness to wavelength ratio. Accordingly, highly sensitive SAW sensors can be developed by coating a sensing medium over a layered SAW device and operating at Sezawa mode resonance frequency. The sensitivity can be increased by tuning the ZnO film thickness to wavelength ratio.

  18. An analytical model for force prediction in ball nose micro milling of inclined surfaces

    DEFF Research Database (Denmark)

    Bissacco, Giuliano; Hansen, Hans Nørgaard; De Chiffre, Leonardo

    2010-01-01

    Ball nose micro milling is a key process for the generation of free form surfaces and inclined surfaces often present in mould inserts for micro replication. This paper presents a new cutting force model for ball nose micro milling that is capable of taking into account the effect of the edge rad...

  19. Analytical approximation of the InGaZnO thin-film transistors surface potential

    Science.gov (United States)

    Colalongo, Luigi

    2016-10-01

    Surface-potential-based mathematical models are among the most accurate and physically based compact models of thin-film transistors, and in turn of indium gallium zinc oxide TFTs, available today. However, the need of iterative computations of the surface potential limits their computational efficiency and diffusion in CAD applications. The existing closed-form approximations of the surface potential are based on regional approximations and empirical smoothing functions that could result not accurate enough in particular to model transconductances and transcapacitances. In this work we present an extremely accurate (in the range of nV) and computationally efficient non-iterative approximation of the surface potential that can serve as a basis for advanced surface-potential-based indium gallium zinc oxide TFTs models.

  20. Fuzzy surfaces in GIS and geographical analysis theory, analytical methods, algorithms and applications

    CERN Document Server

    Lodwick, Weldon

    2007-01-01

    Surfaces are a central to geographical analysis. Their generation and manipulation are a key component of geographical information systems (GISs). However, geographical surface data is often not precise. When surfaces are used to model geographical entities, the data inherently contains uncertainty in terms of both position and attribute. Fuzzy Surface in GIS and Geographical Analysis sets out a process to identify the uncertainty in geographic entities. It describes how to successfully obtain, model, analyze, and display data, as well as interpret results within the context of GIS. Focusing on uncertainty that arises from transitional boundaries, the book limits its study to three types of uncertainties: intervals, fuzzy sets, and possibility distributions. The book explains that uncertainty in geographical data typically stems from these three and it is only natural to incorporate them into the analysis and display of surface data. The book defines the mathematics associated with each method for analysis,...

  1. Analytical Model of the Nonlinear Dynamics of Cantilever Tip-Sample Surface Interactions for Various Acoustic-Atomic Force Microscopies

    Science.gov (United States)

    Cantrell, John H., Jr.; Cantrell, Sean A.

    2008-01-01

    A comprehensive analytical model of the interaction of the cantilever tip of the atomic force microscope (AFM) with the sample surface is developed that accounts for the nonlinearity of the tip-surface interaction force. The interaction is modeled as a nonlinear spring coupled at opposite ends to linear springs representing cantilever and sample surface oscillators. The model leads to a pair of coupled nonlinear differential equations that are solved analytically using a standard iteration procedure. Solutions are obtained for the phase and amplitude signals generated by various acoustic-atomic force microscope (A-AFM) techniques including force modulation microscopy, atomic force acoustic microscopy, ultrasonic force microscopy, heterodyne force microscopy, resonant difference-frequency atomic force ultrasonic microscopy (RDF-AFUM), and the commonly used intermittent contact mode (TappingMode) generally available on AFMs. The solutions are used to obtain a quantitative measure of image contrast resulting from variations in the Young modulus of the sample for the amplitude and phase images generated by the A-AFM techniques. Application of the model to RDF-AFUM and intermittent soft contact phase images of LaRC-cp2 polyimide polymer is discussed. The model predicts variations in the Young modulus of the material of 24 percent from the RDF-AFUM image and 18 percent from the intermittent soft contact image. Both predictions are in good agreement with the literature value of 21 percent obtained from independent, macroscopic measurements of sheet polymer material.

  2. First-and Second-Order Displacement Transfer Functions for Structural Shape Calculations Using Analytically Predicted Surface Strains

    Science.gov (United States)

    Ko, William L.; Fleischer, Van Tran

    2012-01-01

    New first- and second-order displacement transfer functions have been developed for deformed shape calculations of nonuniform cross-sectional beam structures such as aircraft wings. The displacement transfer functions are expressed explicitly in terms of beam geometrical parameters and surface strains (uniaxial bending strains) obtained at equally spaced strain stations along the surface of the beam structure. By inputting the measured or analytically calculated surface strains into the displacement transfer functions, one could calculate local slopes, deflections, and cross-sectional twist angles of the nonuniform beam structure for mapping the overall structural deformed shapes for visual display. The accuracy of deformed shape calculations by the first- and second-order displacement transfer functions are determined by comparing these values to the analytically predicted values obtained from finite element analyses. This comparison shows that the new displacement transfer functions could quite accurately calculate the deformed shapes of tapered cantilever tubular beams with different tapered angles. The accuracy of the present displacement transfer functions also are compared to those of the previously developed displacement transfer functions.

  3. New hybrid method for reactive systems from integrating molecular orbital or molecular mechanics methods with analytical potential energy surfaces.

    Science.gov (United States)

    Espinosa-Garciá, Joaquín; Rangel, Cipriano; Navarrete, Marta; Corchado, José C

    2004-09-15

    A computational approach to calculating potential energy surfaces for reactive systems is presented and tested. This hybrid approach is based on integrated methods where calculations for a small model system are performed by using analytical potential energy surfaces, and for the real system by using molecular orbital or molecular mechanics methods. The method is tested on a hydrogen abstraction reaction by using the variational transition-state theory with multidimensional tunneling corrections. The agreement between the calculated and experimental information depends on the quality of the method chosen for the real system. When the real system is treated by accurate quantum mechanics methods, the rate constants are in excellent agreement with the experimental measurements over a wide temperature range. When the real system is treated by molecular mechanics methods, the results are still good, which is very encouraging since molecular mechanics itself is not at all capable of describing this reactive system. Since no experimental information or additional fits are required to apply this method, it can be used to improve the accuracy of molecular orbital methods or to extend the molecular mechanics method to treat any reactive system with the single constraint of the availability of an analytical potential energy surface that describes the model system.

  4. Theory of coherent molecule to surface electron injection: An analytical model

    Indian Academy of Sciences (India)

    S Ramakrishna; T Seideman; F Willig; V May

    2009-09-01

    Electron transfer from a molecular level to empty continuum levels of a substrate is described theoretically. Using a quasicontinuum approach to model the substrate, analytical expressions pertaining to the time-dependent probability among the various levels of the substrate is presented along with its extension to coherently excited molecular vibrational modes. Hidden time scales and dynamics are revealed in the analysis and possible experiments to observe the new results are suggested. We note the applicability of the model to the description of a variety of other phenomena that are formally similar to the electron injection problem, although pertaining to different physics.

  5. A Global Analytical Representation of the Potential Energy Surface of the FHF(-) Anion.

    Science.gov (United States)

    Cornaton, Yann; Marquardt, Roberto

    2016-08-04

    A global analytical representation of the potential energy hypersurface of the lowest adiabatic electronic state of the FHF(-) anion is derived from ab initio calculations at the coupled cluster level of theory with full single and double and perturbative triple excitations using explicitly correlated atomic basis functions. The new compact function of interatomic distances combines covalent short-range and long-range electrostatic interaction forms and assesses accurately both the lowest reaction channels between the F(-) and HF fragments, with reaction enthalpies to within 1 kJ mol(-1), as well as vibrational terms to within 1.5 cm(-1) deviation from experimental values.

  6. Synthesis and processing of ELISA polymer substitute: The influence of surface chemistry and morphology on detection sensitivity

    Energy Technology Data Exchange (ETDEWEB)

    Hosseini, Samira; Ibrahim, Fatimah [Department of Biomedical Engineering, Faculty of Engineering, University of Malaya, Kuala Lumpur 50603 (Malaysia); Center for Innovation in Medical Engineering, Faculty of Engineering, University of Malaya, Kuala Lumpur 50603 (Malaysia); Djordjevic, Ivan, E-mail: ivan.djordjevic@um.edu.my [Department of Biomedical Engineering, Faculty of Engineering, University of Malaya, Kuala Lumpur 50603 (Malaysia); Center for Innovation in Medical Engineering, Faculty of Engineering, University of Malaya, Kuala Lumpur 50603 (Malaysia); Rothan, Hussin A.; Yusof, Rohana [Department of Molecular Medicine, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur (Malaysia); Marel, Cees van der [Philips Materials Analysis, High Tech Campus 11, 5656 AE Eindhoven (Netherlands); Koole, Leo H. [Department of Biomedical Engineering, Faculty of Engineering, University of Malaya, Kuala Lumpur 50603 (Malaysia); Center for Innovation in Medical Engineering, Faculty of Engineering, University of Malaya, Kuala Lumpur 50603 (Malaysia); Faculty of Health, Medicine and Life Sciences, Maastricht University (Netherlands)

    2014-10-30

    Highlights: • Polyacrylate coatings with controlled surface functionalities. • Impact of surface chemistry and morphology on dengue antibody immobilization. • Enhancement of detection signal as a result of bio-activation of polymer surface. - Abstract: Despite the known drawbacks of enzyme-linked immunosorbent assay (ELISA), one of the deficiencies that have relatively been ignored is the performance of ELISA substrate itself. Polystyrene (PS), as the cost effective material of choice for mass production of ELISA well-plates, has shown obvious lacks of suitable physical and chemical properties for protein attachment. The general concept of this work was to develop a potential substrate that can be suggested as a material of choice for production of a new generation of ELISA analytical kits. Spin-coated thin films of polymethyl methacrylate-co-methacrylic acid (PMMA-co-MAA) on silicon surfaces were designed and processed for detection of dengue virus. Coated surfaces of different molar ratios have been investigated as carboxyl-functionalized layers for obtaining platform for biomolecule immobilization with high level of protein activity. To improve the sensitivity of detection, we have used amine functional “spacers”, hexamethylenediamine (HMDA) and polyethyleneimine (PEI), which were covalently bonded to the surfaces of PMMA-co-MAA coatings. Results demonstrate that the variation of surface concentration of carboxyl groups of PMMA-co-MAA can be used to control the amine surface concentration after carbodiimide coupling with HMDA and PEI spacers. The presence of amine spacers increases hydrophilicity of the coatings and significantly impacts the polymer surface morphology. In particular, protein immobilization via amine-bearing spacers has been achieved in two effective steps: (1) carbodiimide bonding between amine spacer molecules and PMMA-co-MAA polymer coatings; and (2) covalent immobilization of antibody via glutaraldehyde reaction with amine groups

  7. Sensitivity of a general circulation model to land surface parameters in African tropical deforestation experiments

    Energy Technology Data Exchange (ETDEWEB)

    Maynard, K.; Royer, J.F. [Meteo-France CNRM, 42 Avenue G. Coriolis, 31057, Toulouse Cedex 1 (France)

    2004-06-01

    During the last two decades, several land surface schemes for use in climate, regional and/or mesoscale, hydrological and ecological models have been designed. Incorrect parametrization of land-surface processes and prescription of the surface parameters in atmospheric modeling, can result in artificial changes of the horizontal gradient of the sensible heat flux. Thus, an error in horizontal temperature gradient within the lower atmosphere may be introduced. The reliability of the model depends on the quality of boundary layer scheme implemented and its sensitivity to the bare soil and vegetation parameters. In this study, a series of sensitivity experiments has been conducted over broad time scales, using a version of the ARPEGE Climate Model coupled to the ISBA land surface scheme in order to investigate model sensitivity to separate changes in land surface parameters over Africa. Effects of perturbing vegetation cover, distribution of soil depth, albedo of vegetation, roughness length, leaf area index and minimum stomatal resistance were explored by using a simple statistical analysis. Identifying which parameters are important in controlling turbulent energy fluxes, temperature and soil moisture is dependent on which variables are used to determine sensibility, which type of vegetation and climate regime is being simulated and the magnitude and sign of the parameter change. This study does not argue that a particular parameter is important in ISBA, rather it shows that no general ranking of parameters is possible. So, it is essential to specify all land surface parameters with greater precision when attempting to determine the climate response to modification of the land surface. The implication of ISBA being sensitive to parameters that cannot be validated suggests that there will always be considerable doubt over the predictive quality of land-surface schemes. (orig.)

  8. Friction Sensitivity of Nitramines. Part Ⅳ:Links to Surface Electrostatic Potentials%Friction Sensitivity of Nitramines.Part Ⅳ: Links to Surface Electrostatic Potentials

    Institute of Scientific and Technical Information of China (English)

    Zdeněk Frledl; Marcela Jungová; Svatopluk Zeman; Adéla Husarová

    2011-01-01

    The friction sensitivity (FS) of five aliphatic linear and eight cyclic nitramines has been determined and correlated with DFT B3LYP/6-31-G(d,p) // 6-311 + G(d,p) positive ( VS,max ) and negative ( VS,min ) extremes of molecular surface electrostatic potentials VS (r).While there is an ambiguous relationship between the VS.max values and FS values,the decrease of FS is connected ( more or less) with increase in VS,min values.

  9. Gold nanolenses generated by laser ablation-efficient enhancing structure for surface enhanced Raman scattering analytics and sensing.

    Science.gov (United States)

    Kneipp, Janina; Li, Xiangting; Sherwood, Margaret; Panne, Ulrich; Kneipp, Harald; Stockman, Mark I; Kneipp, Katrin

    2008-06-01

    Nanoaggregates formed by metal spheres of different radii and interparticle distances represent finite, deterministic, self-similar systems that efficiently concentrate optical fields and act as "nanolenses". Here we verify experimentally the theoretical concept of nanolenses and explore their potential as enhancing nanostructures in surface enhanced Raman scattering (SERS). Self-similar structures formed by gold nanospheres of different sizes are generated by laser ablation from solid gold into water. These nanolenses exhibit SERS enhancement factors on the order of 10(9). The "chemically clean" preparation process provides several advantages over chemically prepared nanoaggregates and makes the stable and biocompatible gold nanolenses potent enhancing structures for various analytical and sensing applications.

  10. Surface chemistry regulates the sensitivity and tolerability of osteoblasts to various magnitudes of fluid shear stress.

    Science.gov (United States)

    Li, Yan; Wang, Jinfeng; Xing, Juan; Wang, Yuanliang; Luo, Yanfeng

    2016-12-01

    Scaffolds provide a physical support for osteoblasts and act as the medium to transfer mechanical stimuli to cells. To verify our hypothesis that the surface chemistry of scaffolds regulates the perception of cells to mechanical stimuli, the sensitivity and tolerability of osteoblasts to fluid shear stress (FSS) of various magnitudes (5, 12, 20 dynes/cm(2) ) were investigated on various surface chemistries (-OH, -CH3 , -NH2 ), and their follow-up effects on cell proliferation and differentiation were examined as well. The sensitivity was characterized by the release of adenosine triphosphate (ATP), nitric oxide (NO) and prostaglandin E2 (PGE2 ) while the tolerability was by cellular membrane integrity. The cell proliferation was characterized by S-phase cell fraction and the differentiation by ALP activity and ECM expression (fibronectin and type I collagen). As revealed, osteoblasts demonstrated higher sensitivity and lower tolerability on OH and CH3 surfaces, yet lower sensitivity and higher tolerability on NH2 surfaces. Observations on the focal adhesion formation, F-actin organization and cellular orientation before and after FSS exposure suggest that the potential mechanism lies in the differential control of F-actin organization and focal adhesion formation by surface chemistry, which further divergently mediates the sensitivity and tolerability of ROBs to FSS and the follow-up cell proliferation and differentiation. These findings are essentially valuable for design/selection of desirable surface chemistry to orchestrate with FSS stimuli, inducing appropriate cell responses and promoting bone formation. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2978-2991, 2016.

  11. A novel optimal sensitivity design scheme for yarn tension sensor using surface acoustic wave device.

    Science.gov (United States)

    Lei, Bingbing; Lu, Wenke; Zhu, Changchun; Liu, Qinghong; Zhang, Haoxin

    2014-08-01

    In this paper, we propose a novel optimal sensitivity design scheme for the yarn tension sensor using surface acoustic wave (SAW) device. In order to obtain the best sensitivity, the regression model between the size of the SAW yarn tension sensor substrate and the sensitivity of the SAW yarn tension sensor was established using the least square method. The model was validated too. Through analyzing the correspondence between the regression function monotonicity and its partial derivative sign, the effect of the SAW yarn tension sensor substrate size on the sensitivity of the SAW yarn tension sensor was investigated. Based on the regression model, a linear programming model was established to gain the optimal sensitivity of the SAW yarn tension sensor. The linear programming result shows that the maximum sensitivity will be achieved when the SAW yarn tension sensor substrate length is equal to 15 mm and its width is equal to 3mm within a fixed interval of the substrate size. An experiment of SAW yarn tension sensor about 15 mm long and 3mm wide was presented. Experimental results show that the maximum sensitivity 1982.39 Hz/g was accomplished, which confirms that the optimal sensitivity design scheme is useful and effective. Copyright © 2014. Published by Elsevier B.V.

  12. Enhanced Sensitivity of Surface Plasmon Resonance Sensor Based on Bilayers of Silver-Barium Titanate

    Directory of Open Access Journals (Sweden)

    S. Fouad

    2016-12-01

    Full Text Available Surface plasmon resonance (SPR sensors have been widely adopted with various fields such as physics, chemistry, biology and biochemistry. SPR sensor has many advantages like the less number of sensing samples required, freedom of electromagnetic interference and higher sensitivity. This research investigates the phase interrogation technique of a surface plasmon resonance sensor based on silver and thin film dielectric material of Barium titanate layers. Barium titanate (BaTiO3 layer is adopted due to its excellent dielectric properties such as high dielectric constant and low dielectric loss. The numerical results demonstrate that the fusion of the proposed material BaTiO3 layer into surface plasmon resonance sensor yields a higher sensitivity of 280 degree/RIU in comparison with surface plasmon resonance sensor without BaTiO3 layer which shows only a sensitivity of 120 degree/RIU. As the thickness of this layer increases from 5 nm to 10 nm, the sensitivity is enhanced from 160 degree/RIU to 280 degree/RIU for a fixed metal layer of silver with a thickness of (70 nm.

  13. Enhancing the gas sensitivity of surface plasmon resonance with a nanoporous silica matrix

    NARCIS (Netherlands)

    Berrier, A.; Offermans, P.; Cools, R.; Megen, B. van; Knoben, W.; Vecchi, G.; Rivas, J.G.; Crego-Calama, M.; Brongersma, S.H.

    2011-01-01

    The development of sensing schemes for the detection of health-threatening gases is an attractive subject for research towards novel integrated autonomous sensor systems. We report here on a novel way of sensing NO\\2 by surface plasmon resonance (SPR) using a gas-sensitive layer composed of

  14. Influence of electromagnetic interferences on the gravimetric sensitivity of surface acoustic waveguides

    CERN Document Server

    Francis, L; De Palma, R; Bertrand, P; Campitelli, A

    2003-01-01

    Surface acoustic waveguides are increasing in interest for (bio)chemical detection. The surface mass modification leads to measurable changes in the propagation properties of the waveguide. Among a wide variety of waveguides, Love mode has been investigated because of its high gravimetric sensitivity. The acoustic signal launched and detected in the waveguide by electrical transducers is accompanied by an electromagnetic wave; the interaction of the two signals, easily enhanced by the open structure of the sensor, creates interference patterns in the transfer function of the sensor. The influence of these interferences on the gravimetric sensitivity is presented, whereby the structure of the entire sensor is modelled. We show that electromagnetic interferences generate an error in the experimental value of the sensitivity. This error is different for the open and the closed loop configurations of the sensor. The theoretical approach is completed by the experimentation of an actual Love mode sensor operated un...

  15. Enhancement and control of surface plasmon resonance sensitivity using grating in conical mounting configuration.

    Science.gov (United States)

    Perino, M; Pasqualotto, E; Scaramuzza, M; De Toni, A; Paccagnella, A

    2015-01-15

    In this work we propose a method to enhance and control the angular sensitivity of a grating coupled surface plasmon resonance (GCSPR) sensor. We lighted a silver grating, mounted in conical configuration, with a laser source and we measured the transmittance of the grating as a function of the azimuthal angle. To evaluate the sensitivity, grating surface was functionalized with four different alkanethiol self assembled monolayers (SAM) and the correspondent azimuthal transmittance peak shifts were measured. The sensitivity control was performed by simply change the light incident angle. This method offers the possibility to design dynamic GCSPR sensor benches that can be used to amplify the SPR angle shift at any step of a biological detection process.

  16. Calculating the sensitivity of wind turbine loads to wind inputs using response surfaces

    DEFF Research Database (Denmark)

    Rinker, Jennifer M.

    2016-01-01

    This paper presents a methodology to calculate wind turbine load sensitivities to turbulence parameters through the use of response surfaces. A response surface is a high-dimensional polynomial surface that can be calibrated to any set of input/output data and then used to generate synthetic data...... parameters examined in this paper, the variance caused by the Kaimal length scale and nonstationarity parameter are negligible. Thus, the findings in this paper represent the first systematic evidence that stochastic wind turbine load response statistics can be modeled purely by mean wind wind speed...

  17. Quantitative determination of BAF312, a S1P-R modulator, in human urine by LC-MS/MS: prevention and recovery of lost analyte due to container surface adsorption.

    Science.gov (United States)

    Li, Wenkui; Luo, Suyi; Smith, Harold T; Tse, Francis L S

    2010-02-15

    Analyte loss due to non-specific binding, especially container surface adsorption, is not uncommon in the quantitative analysis of urine samples. In developing a sensitive LC-MS/MS method for the determination of a drug candidate, BAF312, in human urine, a simple procedure was outlined for identification, confirmation and prevention of analyte non-specific binding to a container surface and to recover the 'non-specific loss' of an analyte, if no transfer has occurred to the original urine samples. Non-specific binding or container surface adsorption can be quickly identified by using freshly spiked urine calibration standards and pre-pooled QC samples during a LC-MS/MS feasibility run. The resulting low recovery of an analyte in urine samples can be prevented through the use of additives, such as the non-ionic surfactant Tween-80, CHAPS and others, to the container prior to urine sample collection. If the urine samples have not been transferred from the bulk container, the 'non-specific binding' of an analyte to the container surface can be reversed by the addition of a specified amount of CHAPS, Tween-80 or bovine serum albumin, followed by appropriate mixing. Among the above agents, Tween-80 is the most cost-effective. beta-cyclodextrin may be suitable in stabilizing the analyte of interest in urine via pre-treating the matrix with the agent. However, post-addition of beta-cyclodextrin to untreated urine samples does not recover the 'lost' analyte due to non-specific binding or container surface adsorption. In the case of BAF312, a dynamic range of 0.0200-20.0 ng/ml in human urine was validated with an overall accuracy and precision for QC sample results ranging from -3.2 to 5.1% (bias) and 3.9 to 10.2% (CV), respectively. Pre- and post-addition of 0.5% (v/v) Tween-80 to the container provided excellent overall analyte recovery and minimal MS signal suppression when a liquid-liquid extraction in combination with an isocratic LC separation was employed. The

  18. Shotgun proteomic analytical approach for studying proteins adsorbed onto liposome surface

    KAUST Repository

    Capriotti, Anna Laura

    2011-07-02

    The knowledge about the interaction between plasma proteins and nanocarriers employed for in vivo delivery is fundamental to understand their biodistribution. Protein adsorption onto nanoparticle surface (protein corona) is strongly affected by vector surface characteristics. In general, the primary interaction is thought to be electrostatic, thus surface charge of carrier is supposed to play a central role in protein adsorption. Because protein corona composition can be critical in modifying the interactive surface that is recognized by cells, characterizing its formation onto lipid particles may serve as a fundamental predictive model for the in vivo efficiency of a lipidic vector. In the present work, protein coronas adsorbed onto three differently charged cationic liposome formulations were compared by a shotgun proteomic approach based on nano-liquid chromatography-high-resolution mass spectrometry. About 130 proteins were identified in each corona, with only small differences between the different cationic liposome formulations. However, this study could be useful for the future controlled design of colloidal drug carriers and possibly in the controlled creation of biocompatible surfaces of other devices that come into contact with proteins into body fluids. © 2011 Springer-Verlag.

  19. Analytic geometry

    CERN Document Server

    Burdette, A C

    1971-01-01

    Analytic Geometry covers several fundamental aspects of analytic geometry needed for advanced subjects, including calculus.This book is composed of 12 chapters that review the principles, concepts, and analytic proofs of geometric theorems, families of lines, the normal equation of the line, and related matters. Other chapters highlight the application of graphing, foci, directrices, eccentricity, and conic-related topics. The remaining chapters deal with the concept polar and rectangular coordinates, surfaces and curves, and planes.This book will prove useful to undergraduate trigonometric st

  20. Leveraging zinc interstitials and oxygen vacancies for sensitive biomolecule detection through selective surface functionalization

    Science.gov (United States)

    Radha Shanmugam, Nandhinee; Muthukumar, Sriram; Chaudhry, Shajee; Prasad, Shalini

    2015-03-01

    In this study, functionally engineered EIS technique was implemented to investigate the influence of surface functionalization on sensitivity of biomolecule detection using nanostructured ZnO platform. Organic molecules with thiol and carboxylic functional groups were chosen to control biomolecule immobilization on zinc and oxygen-terminated 2D planar and 1D nanostructured ZnO surfaces. The amount of functionalization and its influence on charge perturbations at the ZnO-electrolyte interface were studied using fluorescence and EIS measurements. We observed the dependence of charge transfer on both the polarity of platform and concentration of cross-linker molecules. Such selectively modified surfaces were used for detection of cortisol, a major stress indicator. Results demonstrated preferential binding of thiol groups to Zn terminations and thus leveraging ZnO interstitials increases the sensitivity of detection over larger dynamic range with detection limit at 10fg/mL.

  1. Construction of supported lipid membrane modified piezoelectric biosensor for sensitive assay of cholera toxin based on surface-agglutination of ganglioside-bearing liposomes.

    Science.gov (United States)

    Chen, Huan; Hu, Qing-Yuan; Yue-Zheng; Jiang, Jian-Hui; Shen, Guo-Li; Yu, Ru-Qin

    2010-01-11

    A novel piezoelelctric biosensor has been developed for cholera toxin (CT) detection based on the analyte-mediated surface-agglutination of ganglioside (GM1)-functionalized liposomes. To achieve a CT-specific agglutination at the surface, the gold electrode is modified by a GM1-functionalized supported lipid membrane via spontaneous spread of the liposomes on a self-assembled monolayer of a long-chain alkanethiol. In the presence of CT, the GM1-incorporated liposomes in assay medium will rapidly specifically agglutinate at the electrode surface through the binding of CT to GM1 on the electrode surface and the liposome interface. This results in an enormous mass loading on the piezoelelctric crystal as well as a significant increase of density and viscosity at the interface, thereby generating a decrease in frequency of the piezoelelctric crystal. The combination of mass loading with interfacial change in the surface-agglutination reaction allows the developed piezoelelctric biosensor to show substantial signal amplification in response to the analyte CT. The detection limit can be achieved as low as 25 ng mL(-1) CT. This is the first demonstration on CT detection based on specific surface-agglutination of GM1-modified liposomes. The supported lipid layer based sensing interface can be prepared readily and renewably, making the developed technique especially useful for simple, reusable and sensitive determination of proteins.

  2. Silver dendrites decorated filter membrane as highly sensitive and reproducible three dimensional surface enhanced Raman scattering substrates

    Science.gov (United States)

    Zhao, Bin; Lu, Ya; Zhang, Congyun; Fu, Yizheng; Moeendarbari, Sina; Shelke, Sandesh R.; Liu, Yaqing; Hao, Yaowu

    2016-11-01

    We report a novel and flexible surface enhanced Raman scattering (SERS) substrate based on filter membranes decorated with silver dendritic nanostructures. The SERS-active substrate was fabricated via electrodeposition, where hierarchical silver dendrites were uniformly and firmly deposited within and on the top of the porous filter membranes. The morphological evolution of silver dendrites was investigated at different deposition times, and the effect of the components of electrolyte was also studied. Finite difference time domain (FDTD) simulations were performed to reveal the distribution of electric filed when Ag dendrites were illuminated with 785 nm light. Such 3D SERS-active substrate exhibits extremely high sensitivity and excellent reproducibility. Raman signal sensitivity for rhodamine 6G was tested as high as 1 × 10-11 M with 12% average intensity variations at the major Raman peak. Additionally, the as-synthesized robust substrate displays high stability under an ambient condition for several months. This 3D eco-friendly filter membrane-based substrate provides not only high density of SERS hot spots, but also a very large area for capturing target analytes. It has potential applications for the detection of trace organic contaminants in the environment.

  3. Application of surface analytical methods for hazardous situation in the Adriatic Sea: monitoring of organic matter dynamics and oil pollution

    Science.gov (United States)

    Pletikapić, Galja; Ivošević DeNardis, Nadica

    2017-01-01

    Surface analytical methods are applied to examine the environmental status of seawaters. The present overview emphasizes advantages of combining surface analytical methods, applied to a hazardous situation in the Adriatic Sea, such as monitoring of the first aggregation phases of dissolved organic matter in order to potentially predict the massive mucilage formation and testing of oil spill cleanup. Such an approach, based on fast and direct characterization of organic matter and its high-resolution visualization, sets a continuous-scale description of organic matter from micro- to nanometre scales. Electrochemical method of chronoamperometry at the dropping mercury electrode meets the requirements for monitoring purposes due to the simple and fast analysis of a large number of natural seawater samples enabling simultaneous differentiation of organic constituents. In contrast, atomic force microscopy allows direct visualization of biotic and abiotic particles and provides an insight into structural organization of marine organic matter at micro- and nanometre scales. In the future, merging data at different spatial scales, taking into account experimental input on micrometre scale, observations on metre scale and modelling on kilometre scale, will be important for developing sophisticated technological platforms for knowledge transfer, reports and maps applicable for the marine environmental protection and management of the coastal area, especially for tourism, fishery and cruiser trafficking.

  4. Communication: Chemisorption of muonium on gold nanoparticles: A sensitive new probe of surface magnetism and reactivity

    Science.gov (United States)

    Dehn, M. H.; Arseneau, D. J.; Böni, P.; Bridges, M. D.; Buck, T.; Cortie, D. L.; Fleming, D. G.; Kelly, J. A.; MacFarlane, W. A.; MacLachlan, M. J.; McFadden, R. M. L.; Morris, G. D.; Wang, P.-X.; Xiao, J.; Zamarion, V. M.; Kiefl, R. F.

    2016-11-01

    Chemisorption of muonium onto the surface of gold nanoparticles has been observed. Muonium (μ+e- ), a light hydrogen-like atom, reacts chemically with uncapped 7 nm gold nanoparticles embedded in mesoporous silica (SBA-15) with a strong temperature-dependent rate. The addition rate is fast enough to allow coherent spin transfer into a diamagnetic muon state on the nanoparticle surface. The muon is well established as a sensitive probe of static or slowly fluctuating magnetic fields in bulk matter. These results represent the first muon spin rotation signal on a nanoparticle surface or any metallic surface. Only weak magnetic effects are seen on the surface of these Au nanoparticles consistent with Pauli paramagnetism.

  5. Design of Ag nanorods for sensitivity and thermal stability of surface-enhanced Raman scattering

    Science.gov (United States)

    Ma, Lingwei; Zhang, Zhengjun; Huang, Hanchen

    2017-10-01

    The technology of surface-enhanced Raman scattering (SERS) has found many applications and may find more if it can possess both sensitivity and thermal stability. This paper reports a rational design of Ag nanorods to simultaneously achieve two competing goals: the sensitivity and the thermal stability of SERS substrates. The Ag nanorods are designed and synthesized using physical vapor deposition under the condition of glancing angle incidence. The working pressure of the vacuum chamber is controlled so the mean free path of depositing atoms is comparable to the dimension of the chamber, so as to grow Ag nanorods with small diameter, and small but clear separation for optimal SERS sensitivity. Such Ag nanorods are further capped with Al2O3 on their top surfaces to reduce the diffusion-induced coarsening at high temperatures, and thereby to improve the thermal stability for SERS detections. Meanwhile, since the side surfaces of Ag nanorods are not coated with oxides in this approach, the SERS sensitivity is largely preserved while good thermal stability is achieved.

  6. Mass sensitivity analysis and designing of surface acoustic wave resonators for chemical sensors

    Science.gov (United States)

    Kshetrimayum, Roshan; Yadava, R. D. S.; Tandon, R. P.

    2009-05-01

    The sensitivity of surface acoustic wave (SAW) chemical sensors depends on several factors such as the frequency and phase point of SAW device operation, sensitivity of the SAW velocity to surface mass loading, sensitivity of the SAW oscillator resonance to the loop phase shift, film thickness and oscillator electronics. This paper analyzes the influence of the phase point of operation in SAW oscillator sensors based on two-port resonator devices. It is found that the mass sensitivity will be enhanced if the SAW device has a nonlinear dependence on the frequency (delay ~ frequency-1). This requires the device to generate and operate in a ωτg(ω) = const region in the device passband, where ω denotes the angular frequency of oscillation and τg(ω) denotes the phase slope of the SAW resonator device. A SAW coupled resonator filter (CRF) that take advantage of mode coupling is considered in realizing such a device to help in shaping the phase transfer characteristics of a high mass sensitivity sensor. The device design and simulation results are presented within the coupling-of-modes formalism.

  7. Enhancing dye-sensitized solar cell efficiency by anode surface treatments

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Chao-Hsuan [Department of Chemical Engineering, National Cheng Kung University, Tainan 70101, Taiwan (China); Lin, Hsin-Han [Institute of Nanotechnology and Microsystems Engineering, National Cheng Kung University, Tainan 70101, Taiwan (China); Chen, Chin-Cheng [Department of Chemical Engineering, National Cheng Kung University, Tainan 70101, Taiwan (China); Hong, Franklin C.-N., E-mail: hong@mail.ncku.edu.tw [Department of Chemical Engineering, National Cheng Kung University, Tainan 70101, Taiwan (China); Institute of Nanotechnology and Microsystems Engineering, National Cheng Kung University, Tainan 70101, Taiwan (China); Center for Energy Technology and Strategy, National Cheng Kung University, Tainan 70101, Taiwan (China)

    2014-11-03

    In this study, titanium substrates treated with HF solution and KOH solution sequentially forming micro- and nano-structures were used for the fabrication of flexible dye-sensitized solar cells (DSSCs). After wet etching treatments, the titanium substrates were then exposed to the O{sub 2} plasma treatment and further immersed in titanium tetrachloride (TiCl{sub 4}) solution. The process conditions for producing a very thin TiO{sub 2} blocking layer were studied, in order to avoid solar cell current leakage for increasing the solar cell efficiency. Subsequently, TiO{sub 2} nanoparticles were spin-coated on Ti substrates with varied thickness. The dye-sensitized solar cells on the titanium substrates were subjected to simulate AM 1.5 G irradiation of 100 mW/cm{sup 2} using backside illumination mode. Surface treatments of Ti substrate and TiO{sub 2} anode were found to play a significant role in improving the efficiency of DSSC. The efficiencies of the backside illumination solar cells were raised from 4.6% to 7.8% by integrating these surface treatments. - Highlights: • The flexible dye-sensitized solar cell (DSSC) device can be fabricated. • Many effective surface treatment methods to improve DSSC efficiency are elucidated. • The efficiency is dramatically enhanced by integrating surface treatment methods. • The back-illuminated DSSC efficiency was raised from 4.6% to 7.8%.

  8. Characterization of Natural Dyes and Traditional Korean Silk Fabric by Surface Analytical Techniques

    Directory of Open Access Journals (Sweden)

    Yeonhee Lee

    2013-05-01

    Full Text Available Time-of-flight secondary ion mass spectrometry (TOF-SIMS and X-ray photoelectron spectroscopy (XPS are well established surface techniques that provide both elemental and organic information from several monolayers of a sample surface, while also allowing depth profiling or image mapping to be carried out. The static TOF-SIMS with improved performances has expanded the application of TOF-SIMS to the study of a variety of organic, polymeric and biological materials. In this work, TOF-SIMS, XPS and Fourier Transform Infrared (FTIR measurements were used to characterize commercial natural dyes and traditional silk fabric dyed with plant extracts dyes avoiding the time-consuming and destructive extraction procedures necessary for the spectrophotometric and chromatographic methods previously used. Silk textiles dyed with plant extracts were then analyzed for chemical and functional group identification of their dye components and mordants. TOF-SIMS spectra for the dyed silk fabric showed element ions from metallic mordants, specific fragment ions and molecular ions from plant-extracted dyes. The results of TOF-SIMS, XPS and FTIR are very useful as a reference database for comparison with data about traditional Korean silk fabric and to provide an understanding of traditional dyeing materials. Therefore, this study shows that surface techniques are useful for micro-destructive analysis of plant-extracted dyes and Korean dyed silk fabric.

  9. Sensitivity of Asian Summer Monsoon precipitation to tropical sea surface temperature anomalies

    Science.gov (United States)

    Fan, Lei; Shin, Sang-Ik; Liu, Zhengyu; Liu, Qinyu

    2016-10-01

    Sensitivity of Asian Summer Monsoon (ASM) precipitation to tropical sea surface temperature (SST) anomalies was estimated from ensemble simulations of two atmospheric general circulation models (GCMs) with an array of idealized SST anomaly patch prescriptions. Consistent sensitivity patterns were obtained in both models. Sensitivity of Indian Summer Monsoon (ISM) precipitation to cooling in the East Pacific was much weaker than to that of the same magnitude in the local Indian-western Pacific, over which a meridional pattern of warm north and cold south was most instrumental in increasing ISM precipitation. This indicates that the strength of the ENSO-ISM relationship is due to the large-amplitude East Pacific SST anomaly rather than its sensitivity value. Sensitivity of the East Asian Summer Monsoon (EASM), represented by the Yangtze-Huai River Valley (YHRV, also known as the meiyu-baiu front) precipitation, is non-uniform across the Indian Ocean basin. YHRV precipitation was most sensitive to warm SST anomalies over the northern Indian Ocean and the South China Sea, whereas the southern Indian Ocean had the opposite effect. This implies that the strengthened EASM in the post-Niño year is attributable mainly to warming of the northern Indian Ocean. The corresponding physical links between these SST anomaly patterns and ASM precipitation were also discussed. The relevance of sensitivity maps was justified by the high correlation between sensitivity-map-based reconstructed time series using observed SST anomaly patterns and actual precipitation series derived from ensemble-mean atmospheric GCM runs with time-varying global SST prescriptions during the same period. The correlation results indicated that sensitivity maps derived from patch experiments were far superior to those based on regression methods.

  10. Investigation into Mass Loading Sensitivity of Sezawa Wave Mode-Based Surface Acoustic Wave Sensors

    OpenAIRE

    N. Ramakrishnan; Parthiban, R.; Sawal Hamid Md Ali; Md. Shabiul Islam; Ajay Achath Mohanan

    2013-01-01

    In this work mass loading sensitivity of a Sezawa wave mode based surface acoustic wave (SAW) device is investigated through finite element method (FEM) simulation and the prospects of these devices to function as highly sensitive SAW sensors is reported. A ZnO/Si layered SAW resonator is considered for the simulation study. Initially the occurrence of Sezawa wave mode and displacement amplitude of the Rayleigh and Sezawa wave mode is studied for lower ZnO film thickness. Further, a thin film...

  11. Analytical sensitivity of staining and molecular techniques for the detection of Cryptosporidium spp. oocysts isolated from bovines in water samples: a preliminary study

    Directory of Open Access Journals (Sweden)

    A Díaz-Lee

    2015-01-01

    Full Text Available Cryptosporidium spp. is a globally distributed protozoan that causes digestive disease in different animals including humans. Excreted oocysts contaminate water and soil, constituting a public health threat. Sensitive and fast methods to detect oocysts in water samples are necessary due to the small number of oocysts present in the environment and their low infectious dose. This study compared the analytical sensitivity of two staining techniques, modified Ziehl-Neelsen and Auramine versus a nested PCR that amplifies a region of ~520bp from 18S rDNA gene, to detect Cryptosporidium spp. in water samples. Water was inoculated with oocysts using serial dilutions, and then a water filtration method was used to recover the parasite oocysts. The staining techniques had similar analytical sensitivity, detecting 8 oocysts/mL, while the nested PCR detected down to 6 oocysts/mL. In conclusion, all of these methods are effective for Cryptosporidium spp. detection in water samples, contributing to the implementation of standardized diagnostic methods for environmental water infectious agents.

  12. A sensitive electrochemiluminescence cytosensor for quantitative evaluation of epidermal growth factor receptor expressed on cell surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Yanjuan; Zhang, Shaolian; Wen, Qingqing; Huang, Hongxing; Yang, Peihui, E-mail: typh@jnu.edu.cn

    2015-06-30

    Highlights: • EGF-cytosensor was used for evaluating EGFR expression level on cell surfaces. • CdSQDs and EGF were coated on magnetic beads (MBs) for ECL-probe. • Good sensitivity was achieved due to the signal amplification of ECL-probe. - Abstract: A sensitive electrochemiluminescence (ECL) strategy for evaluating the epidermal growth factor receptor (EGFR) expression level on cell surfaces was designed by integrating the specific recognition of EGFR expressed on MCF-7 cell surfaces with an epidermal growth factor (EGF)-funtionalized CdS quantum dots (CdSQDs)-capped magnetic bead (MB) probe. The high sensitivity of ECL probe of EGF-funtionalized CdSQD-capped-MB was used for competitive recognition with EGFR expressed on cell surfaces with recombinant EGFR protein. The changes of ECL intensity depended on both the cell number and the expression level of EGFR receptor on cell surfaces. A wide linear response to cells ranging from 80 to 4 × 10{sup 6} cells mL{sup −1} with a detection limit of 40 cells mL{sup −1} was obtained. The EGF-cytosensor was used to evaluate EGFR expression levels on MCF-7 cells, and the average number of EGFR receptor on single MCF-7 cells was 1.35 × 10{sup 5} with the relative standard deviation of 4.3%. This strategy was further used for in-situ and real-time evaluating EGFR receptor expressed on cell surfaces in response to drugs stimulation at different concentration and incubation time. The proposed method provided potential applications in the detection of receptors on cancer cells and anticancer drugs screening.

  13. Notch Sensitivity of Woven Ceramic Matrix Composites Under Tensile Loading: An Experimental, Analytical, and Finite Element Study

    Science.gov (United States)

    Haque, A.; Ahmed, L.; Ware, T.; Jeelani, S.; Verrilli, Michael J. (Technical Monitor)

    2001-01-01

    The stress concentrations associated with circular notches and subjected to uniform tensile loading in woven ceramic matrix composites (CMCs) have been investigated for high-efficient turbine engine applications. The CMC's were composed of Nicalon silicon carbide woven fabric in SiNC matrix manufactured through polymer impregnation process (PIP). Several combinations of hole diameter/plate width ratios and ply orientations were considered in this study. In the first part, the stress concentrations were calculated measuring strain distributions surrounding the hole using strain gages at different locations of the specimens during the initial portion of the stress-strain curve before any microdamage developed. The stress concentration was also calculated analytically using Lekhnitskii's solution for orthotropic plates. A finite-width correction factor for anisotropic and orthotropic composite plate was considered. The stress distributions surrounding the circular hole of a CMC's plate were further studied using finite element analysis. Both solid and shell elements were considered. The experimental results were compared with both the analytical and finite element solutions. Extensive optical and scanning electron microscopic examinations were carried out for identifying the fracture behavior and failure mechanisms of both the notched and notched specimens. The stress concentration factors (SCF) determined by analytical method overpredicted the experimental results. But the numerical solution underpredicted the experimental SCF. Stress concentration factors are shown to increase with enlarged hole size and the effects of ply orientations on stress concentration factors are observed to be negligible. In all the cases, the crack initiated at the notch edge and propagated along the width towards the edge of the specimens.

  14. Sensitivity Analysis of the Land Surface Model NOAH-MP for Different Model Fluxes

    Science.gov (United States)

    Mai, Juliane; Thober, Stephan; Samaniego, Luis; Branch, Oliver; Wulfmeyer, Volker; Clark, Martyn; Attinger, Sabine; Kumar, Rohini; Cuntz, Matthias

    2015-04-01

    Land Surface Models (LSMs) use a plenitude of process descriptions to represent the carbon, energy and water cycles. They are highly complex and computationally expensive. Practitioners, however, are often only interested in specific outputs of the model such as latent heat or surface runoff. In model applications like parameter estimation, the most important parameters are then chosen by experience or expert knowledge. Hydrologists interested in surface runoff therefore chose mostly soil parameters while biogeochemists interested in carbon fluxes focus on vegetation parameters. However, this might lead to the omission of parameters that are important, for example, through strong interactions with the parameters chosen. It also happens during model development that some process descriptions contain fixed values, which are supposedly unimportant parameters. However, these hidden parameters remain normally undetected although they might be highly relevant during model calibration. Sensitivity analyses are used to identify informative model parameters for a specific model output. Standard methods for sensitivity analysis such as Sobol indexes require large amounts of model evaluations, specifically in case of many model parameters. We hence propose to first use a recently developed inexpensive sequential screening method based on Elementary Effects that has proven to identify the relevant informative parameters. This reduces the number parameters and therefore model evaluations for subsequent analyses such as sensitivity analysis or model calibration. In this study, we quantify parametric sensitivities of the land surface model NOAH-MP that is a state-of-the-art LSM and used at regional scale as the land surface scheme of the atmospheric Weather Research and Forecasting Model (WRF). NOAH-MP contains multiple process parameterizations yielding a considerable amount of parameters (˜ 100). Sensitivities for the three model outputs (a) surface runoff, (b) soil drainage

  15. Dye-Sensitized Solar Cells Based on High Surface Area Nanocrystalline Zinc Oxide Spheres

    Directory of Open Access Journals (Sweden)

    Pavuluri Srinivasu

    2011-01-01

    Full Text Available High surface area nanocrystalline zinc oxide material is fabricated using mesoporous nanostructured carbon as a sacrificial template through combustion process. The resulting material is characterized by XRD, N2 adsorption, HR-SEM, and HR-TEM. The nitrogen adsorption measurement indicates that the materials possess BET specific surface area ca. 30 m2/g. Electron microscopy images prove that the zinc oxide spheres possess particle size in the range of 0.12 μm–0.17 μm. The nanocrystalline zinc oxide spheres show 1.0% of energy conversion efficiency for dye-sensitized solar cells.

  16. Sensitivity to ultraviolet radiation of Lassa, vaccinia, and Ebola viruses dried on surfaces.

    Science.gov (United States)

    Sagripanti, Jose-Luis; Lytle, C David

    2011-03-01

    Germicidal UV (also known as UVC) provides a means to decontaminate infected environments as well as a measure of viral sensitivity to sunlight. The present study determined UVC inactivation slopes (and derived D(37) values) of viruses dried onto nonporous (glass) surfaces. The data obtained indicate that the UV resistance of Lassa virus is higher than that of Ebola virus. The UV sensitivity of vaccinia virus (a surrogate for variola virus) appeared intermediate between that of the two virulent viruses studied. In addition, the three viruses dried on surfaces showed a relatively small but significant population of virions (from 3 to 10 % of virus in the inoculum) that appeared substantially more protected by their environment from the effect of UV than the majority of virions tested. The findings reported in this study should assist in estimating the threat posed by the persistence of virus in environments contaminated during epidemics or after an accidental or intentional release.

  17. Design of guided Bloch surface wave resonance bio-sensors with high sensitivity

    Science.gov (United States)

    Kang, Xiu-Bao; Wen, Li-Wei; Wang, Zhi-Guo

    2017-01-01

    The sensing performance of bio-sensors based on guided Bloch surface wave (BSW) resonance (GBR) is studied. GBR is realized by coupling the propagating electromagnetic wave with BSW on one side of a one-dimensional photonic crystal slab via the grating on the other side. The sensitivity of the designed bio-sensors is proportional to the grating constant when the wavelength spectrum is analyzed, and inversely proportional to the normal wave vector of the incident electromagnetic wave when the angular spectrum is resolved. For a GBR bio-sensor designed to operate near 70° angle of incidence from air, the angular sensitivity is very high, reaching 128 deg RIU-1. The sensitivity can be substantially increased by designing bio-sensors for operating at larger angles of incidence.

  18. Surface and material analytics based on Dresden-EBIS platform technology

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, M., E-mail: mike.schmidt@dreebit.com; König, J., E-mail: mike.schmidt@dreebit.com [DREEBIT GmbH, Grossroehrsdorf (Germany); Bischoff, L. [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Pilz, W. [Dresden University of Technology, Dresden (Germany); Zschornack, G. [Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany and Dresden University of Technology, Dresden (Germany)

    2015-01-09

    Nowadays widely used mass spectrometry systems utilize energetic ions hitting a sample and sputter material from the surface of a specimen. The generated secondary ions are separated and detected with high mass resolution to determine the target materials constitution. Based on this principle, we present an alternative approach implementing a compact Electron Beam Ion Source (EBIS) in combination with a Liquid Metal Ion Source (LMIS). An LMIS can deliver heavy elements which generate high sputter yields on a target surface. More than 90% of this sputtered material consists of mono- and polyatomic neutrals. These particles are able to penetrate the magnetic field of an EBIS and they will be ionized within the electron beam. A broad spectrum of singly up to highly charged ions can be extracted depending on the operation conditions. Polyatomic ions will decay during the charge-up process. A standard bending magnet or a Wien filter is used to separate the different ion species due to their mass-to-charge ratio. Using different charge states of ions as it is common with EBIS it is also possible to resolve interfering charge-to-mass ratios of only singly charged ions. Different setups for the realization of feeding the electron beam with sputtered atoms of solids will be presented and discussed. As an example the analysis of a copper surface is used to show high-resolution spectra with low background noise. Individual copper isotopes and clusters with different isotope compositions can be resolved at equal atomic numbers. These results are a first step for the development of a new compact low-cost and high-resolution mass spectrometry system. In a more general context, the described technique demonstrates an efficient method for feeding an EBIS with atoms of nearly all solid elements from various solid target materials. The new straightforward design of the presented setup should be of high interest for a broad range of applications in materials research as well as for

  19. Surface and material analytics based on Dresden-EBIS platform technology

    Science.gov (United States)

    Schmidt, M.; König, J.; Bischoff, L.; Pilz, W.; Zschornack, G.

    2015-01-01

    Nowadays widely used mass spectrometry systems utilize energetic ions hitting a sample and sputter material from the surface of a specimen. The generated secondary ions are separated and detected with high mass resolution to determine the target materials constitution. Based on this principle, we present an alternative approach implementing a compact Electron Beam Ion Source (EBIS) in combination with a Liquid Metal Ion Source (LMIS). An LMIS can deliver heavy elements which generate high sputter yields on a target surface. More than 90% of this sputtered material consists of mono- and polyatomic neutrals. These particles are able to penetrate the magnetic field of an EBIS and they will be ionized within the electron beam. A broad spectrum of singly up to highly charged ions can be extracted depending on the operation conditions. Polyatomic ions will decay during the charge-up process. A standard bending magnet or a Wien filter is used to separate the different ion species due to their mass-to-charge ratio. Using different charge states of ions as it is common with EBIS it is also possible to resolve interfering charge-to-mass ratios of only singly charged ions. Different setups for the realization of feeding the electron beam with sputtered atoms of solids will be presented and discussed. As an example the analysis of a copper surface is used to show high-resolution spectra with low background noise. Individual copper isotopes and clusters with different isotope compositions can be resolved at equal atomic numbers. These results are a first step for the development of a new compact low-cost and high-resolution mass spectrometry system. In a more general context, the described technique demonstrates an efficient method for feeding an EBIS with atoms of nearly all solid elements from various solid target materials. The new straightforward design of the presented setup should be of high interest for a broad range of applications in materials research as well as for

  20. A SENSITIVE AND STABLE CONFOCAL FABRY-PEROT INTERFEROMETER FOR SURFACE ULTRASONIC VIBRATION DETECTION

    Institute of Scientific and Technical Information of China (English)

    DING HONG-SHENG; TONG LI-GE; CHEN GENG-HUA

    2001-01-01

    A new confocal Fabry-Pérot interferometer (CFPI) has been constructed. By using both of the conjugate rays,the sensitivity of the system was doubled. Moreover, the negative feedback control loop of a single-chip microcomputer (MCS-51) was applied to stabilize the working point at an optimum position. The system has been used in detecting the piezoelectric ultrasonic vibration on the surface of an aluminium sample.

  1. Analytical investigation of surface plasmon excitation on a graphene sheet using four-wave mixing.

    Science.gov (United States)

    Jamalpoor, Kamal; Zarifkar, Abbas

    2017-01-20

    In the present paper, the general conditions for exciting graphene surface plasmon polaritons (GSPPs) on a suspended graphene using nonlinear optics are investigated. The approach uses the Green's function analysis to derive GSPP fields generated under the basis of momentum conservation using four-wave mixing (FWM). Since the incident beam polarization is challenging in the nonlinear excitation of GSPPs, the significant target of this paper has been set to achieve the conditions for the third-order susceptibility tensor and the wave vectors so that the incident beams with varied polarizations are able to excite GSPPs. Nonlinear optics, in particular FWM, is utilized to compensate the mismatch between the free-space and GSPPs wave vectors. In addition, it avoids the need for applying any patterning or lithography on graphene or its substrate.

  2. Rough surface Au@Ag core-shell nanoparticles to fabricating high sensitivity SERS immunochromatographic sensors.

    Science.gov (United States)

    Fu, Qiangqiang; Liu, Hongwu Liu; Wu, Ze; Liu, An; Yao, Cuize; Li, Xiuqing; Xiao, Wei; Yu, Shiting; Luo, Zhi; Tang, Yong

    2015-11-14

    Immunochromatographic sensors (ICSs) are inexpensive, simple, portable, and robust, thus making ICSs commonplace in clinical diagnoses, food testing, and environmental monitoring. However, commonly used gold nanoparticles (AuNPs) ICSs have low sensitivity. Therefore, we developed highly sensitive surface enhanced Raman scattering (SERS) ICSs. To enhance the sensitivity of SERS ICSs, rough surface core-shell Au@Ag nanoparticles (RSAu@AgNPs) were prepared by coating silver on the surface of gold nanoflowers (AuNFs). Then these nanoparticles were used as SERS substrate in the SERS ICSs, after which the SERS ICSs were implemented to detect haemoglobin and heavy metal cadmium ion (Cd(2+)). The limit of detection (LOD) of the SERS ICSs for detecting haemoglobin was 8 ng/mL, and the linear range of the SERS ICSs was from 31.3 to 2000 ng/mL. The LOD of the SERS ICSs for detecting Cd(2+) was 0.05 ng/mL and the linear analysis range was from 0.05 to 25 ng/mL. The cross reactivity of the SERS ICSs was studied and results showed that the SERS ICSs exhibited highly specific for detection of haemoglobin and Cd(2+), respectively. The SERS ICSs were then used to detect haemoglobin (spiked in serum and in stool) and Cd(2+) (spiked in tap water, river water, and soil leaching water), and the results showed high recovery. These characteristics indicated that SERS ICSs were ideal tools for clinical diagnosis and environmental pollution monitoring.

  3. Analytical model to predict the effect of a finite impedance surface on the propagation properties of 2D Sonic Crystals

    Energy Technology Data Exchange (ETDEWEB)

    Romero-Garcia, V [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas (Spain); Sanchez-Perez, J V [Centro de Tecnologias Fisicas: Acustica, Materiales y Astrofisica, Universidad Politecnica de Valencia (Spain); Garcia-Raffi, L M, E-mail: virogar1@gmail.com [Instituto Universitario de Matematica Pura y Aplicada, Universidad Politecnica de Valencia (Spain)

    2011-07-06

    The use of sonic crystals (SCs) as environmental noise barriers has certain advantages from both the acoustical and the constructive points of view with regard to conventional ones. However, the interaction between the SCs and the ground has not been studied yet. In this work we are reporting a semi-analytical model, based on the multiple scattering theory and on the method of images, to study this interaction considering the ground as a finite impedance surface. The results obtained here show that this model could be used to design more effective noise barriers based on SCs because the excess attenuation of the ground could be modelled in order to improve the attenuation properties of the array of scatterers. The results are compared with experimental data and numerical predictions thus finding good agreement between them.

  4. A new analytical potential energy surface for the singlet state of He{sub 2}H{sup +}

    Energy Technology Data Exchange (ETDEWEB)

    Liang Jingjuan; Zhang Qinggang [College of Physics and Electronics, Shandong Normal University, Jinan 250014 (China); Yang Chuanlu [School of Physics, Ludong University, Yantai 264011 (China); Wang Lizhi [College of Physics and Electronics, Shandong Normal University, Jinan 250014 (China); School of Physics, Ludong University, Yantai 264011 (China)

    2012-03-07

    The analytic potential energy surface (APES) for the exchange reaction of HeH{sup +} (X{sup 1}{Sigma}{sup +}) + He at the lowest singlet state 1{sup 1}A{sup /} has been built. The APES is expressed as Aguado-Paniagua function based on the many-body expansion. Using the adaptive non-linear least-squares algorithm, the APES is fitted from 15 682 ab initio energy points calculated with the multireference configuration interaction calculation with a large d-aug-cc-pV5Z basis set. To testify the new APES, we calculate the integral cross sections for He + H{sup +}He (v= 0, 1, 2, j= 0) {yields} HeH{sup +}+ He by means of quasi-classical trajectory and compare them with the previous result in literature.

  5. Complex surface analytical investigations on hydrogen absorption and desorption processes of a TiMn2-based alloy.

    Science.gov (United States)

    Schülke, Mark; Kiss, Gábor; Paulus, Hubert; Lammers, Martin; Ramachandran, Vaidyanath; Sankaran, Kannan; Müller, Karl-Heinz

    2009-04-01

    Metal hydrides are one of the most promising technologies in the field of hydrogen storage due to their high volumetric storage density. Important reaction steps take place at the very surface of the solid during hydrogen absorption. Since these reaction steps are drastically influenced by the properties and potential contamination of the solid, it is very important to understand the characteristics of the surface, and a variety of analytical methods are required to achieve this. In this work, a TiMn(2)-type metal hydride alloy is investigated by means of high-pressure activation measurements, X-ray photoelectron spectroscopy (XPS), secondary neutral mass spectrometry (SNMS) and thermal desorption mass spectrometry (TDMS). In particular, TDMS is an analytical tool that, in contrast to SIMS or SNMS, allows the hydrogen content in a metal to be quantified. Furthermore, it allows the activation energy for desorption to be determined from TDMS profiles; the method used to achieve this is presented here in detail. In the results section, it is shown that the oxide layer formed during manufacture and long-term storage prevents any hydrogen from being absorbed, and so an activation process is required. XPS measurements show the oxide states of the main alloy elements, and a layer 18 nm thick is determined via SNMS. Furthermore, defined oxide layers are produced and characterized in UHV using XPS. The influence of these thin oxide layers on the hydrogen sorption process is examined using TDMS. Finally, the activation energy of desorption is determined for the investigated alloy using the method presented here, and values of 46 kJ/mol for hydrogen sorbed in UHV and 103 kJ/mol for hydrogen originating from the manufacturing process are obtained.

  6. Cross Validation Through Two-dimensional Solution Surface for Cost-Sensitive SVM.

    Science.gov (United States)

    Gu, Bin; Sheng, Victor; Tay, Keng; Romano, Walter; Li, Shuo

    2016-06-08

    Model selection plays an important role in cost-sensitive SVM (CS-SVM). It has been proven that the global minimum cross validation (CV) error can be efficiently computed based on the solution path for one parameter learning problems. However, it is a challenge to obtain the global minimum CV error for CS-SVM based on one-dimensional solution path and traditional grid search, because CS-SVM is with two regularization parameters. In this paper, we propose a solution and error surfaces based CV approach (CV-SES). More specifically, we first compute a two-dimensional solution surface for CS-SVM based on a bi-parameter space partition algorithm, which can fit solutions of CS-SVM for all values of both regularization parameters. Then, we compute a two-dimensional validation error surface for each CV fold, which can fit validation errors of CS-SVM for all values of both regularization parameters. Finally, we obtain the CV error surface by superposing K validation error surfaces, which can find the global minimum CV error of CS-SVM. Experiments are conducted on seven datasets for cost sensitive learning and on four datasets for imbalanced learning. Experimental results not only show that our proposed CV-SES has a better generalization ability than CS-SVM with various hybrids between grid search and solution path methods, and than recent proposed cost-sensitive hinge loss SVM with three-dimensional grid search, but also show that CV-SES uses less running time.

  7. Teachers' Relationship Closeness with Students as a Resource for Teacher Wellbeing: A Response Surface Analytical Approach.

    Science.gov (United States)

    Milatz, Anne; Lüftenegger, Marko; Schober, Barbara

    2015-01-01

    Teachers' relationship quality with students has been argued to be an important source of teacher wellbeing. Thus, the current study aimed to investigate to what extent teachers' relationship closeness toward students, combined with attachment security is a resource protecting against teacher burnout. Eighty-three elementary school teachers reported on their most and least attached student's relationship closeness, their attachment security and levels of burnout, as measured by emotional exhaustion, depersonalization and personal accomplishment. Response surface analysis (RSA), enabling researchers to investigate the effect of congruence/incongruence of two predictors on an outcome, revealed that teachers' depersonalization and emotional exhaustion were lowest when they developed homogenous close relationships toward the students within their classroom and when teachers in general made congruent relationship experiences. No RSA model could be specified for personal accomplishment, even though a correlational analysis revealed that increasing closeness with students fostered teachers' personal accomplishment. Teachers' secure attachment experiences were not directly related to burnout, but enhanced their capability to establish close relationships toward their students. Findings suggest that teachers' relationships toward students are a resource for the teacher's wellbeing, which highlights once again the importance of student-teacher relationships in education.

  8. Adhesive contact of rough surfaces: comparison between numerical calculations and analytical theories

    CERN Document Server

    Carbone, Giuseppe; Tartaglino, Ugo; 10.1140/epje/i2009-10508-5

    2010-01-01

    We have employed a numerical procedure to analyze the adhesive contact between a soft elastic layer and a rough rigid substrate. The solution of the problem is obtained by calculating the Green's function which links the pressure distribution to the normal displacements at the interface. The problem is then formulated in the form of a Fredholm integral equation of the first kind with a logarithmic kernel, and the boundaries of the contact area are calculated by requiring that the energy of the system is stationary. The methodology has been employed to study the adhesive contact between an elastic semi-infinite solid and a randomly rough rigid profile with a self-affine fractal geometry. We show that, even in presence of adhesion, the true contact area still linearly depends on the applied load. The numerical results are then critically compared with the prediction of an extended version of the Persson's contact mechanics theory, able to handle anisotropic surfaces, as 1D interfaces. It is shown that, for any ...

  9. Effect of Surface Microstructure on the Temperature sensitivity of Burning Rate of Ammonium Perchlorate

    Directory of Open Access Journals (Sweden)

    K. Kishore

    1997-04-01

    Full Text Available Considering Vielle's law and the new thermodynamic model which the authors have developed recently the true dependence of temperature sensitivity of burning rate of ammonium perchlorate (AP on pressure is resolved and experimentally verified for bellet burning. The value of decreases with pressure steeply in regime I' (below 20 atm, but gently in regime I (above 20 atm. The value of powder AP has been determined and it is observed that (powder > (pellet, which clearly suggests that of is innuenced by the surface temperature sensitive parameter and hence by the surface/subsurface microstructure. In powder burning, the buoyant lifting of the particles into the gas phase occurs, Which constitutes the so-called 'free board region' (FER extending just above the true surface. Consequent to the decomposition of AP particles in FER, the condensed phase heat release gets curtailed and (powder becomes larger. A general relationship for in terms of density and surface temperature is suggested, which is applicable to both pellet and powder AP.

  10. Analytical performance issues: comparison of ATP bioluminescence and aerobic bacterial count for evaluating surface cleanliness in an Italian hospital.

    Science.gov (United States)

    Amodio, Emanuele; Cannova, Lucia; Villafrate, Maria Rosaria; Merendino, Anna Maria; Aprea, Luigi; Calamusa, Giuseppe

    2014-01-01

    Contaminated hospital surfaces have been demonstrated to be an important environmental reservoir of microorganisms that can increase the risk of nosocomial infection in exposed patients. As a consequence, cleaning and disinfecting hospital environments play an important role among strategies for preventing healthcare-associated colonization and infections. The aim of the present study was to evaluate whether adenosine triphosphate (ATP) presence, measured by bioluminescence methods, can predict microbiological contamination of hospital surfaces. The study was carried out between September and December 2012 at the University Hospital "P. Giaccone" of Palermo. A total of 193 randomly selected surfaces (tables, lockers, furnishings) were sampled and analyzed in order to assess ATP levels (expressed as relative light units or RLU) and aerobic colony count (ACC) or presence of S. aureus. ACC had median values of 1.85 cfu/cm(2)(interquartile range = 4.16) whereas ATP median was 44.6 RLU/cm(2)(interquartile range = 92.3). Overall, 85 (44.0%) surfaces exceeded the established microbial benchmark: 73 (37.8%) exceeded the 2.5 cfu/cm(2)ACC standard, 5 (2.6%) surfaces were positive for S. aureus and 7 (3.6%) showed both the presence of S. aureus and an ACC of more than 2.5 cfu/cm(2). ACC and bioluminescence showed significant differences in the different surface sites (p < 0.001). A significant correlation was found between ACC and RLU values (p-value < 0.001; R(2)= 0.29) and increasing RLU values were significantly associated with a higher risk of failing the benchmark (p < 0.001). Our data suggest that bioluminescence could help in measuring hygienic quality of hospital surfaces using a quick and sensitive test that can be an useful proxy of microbial contamination; however, further analysis will be necessary to assess the cost-efficacy of this methodology before requiring incorporation in hospital procedures.

  11. Analytical Lower and Upper Bounds for the Threshold Surfaces of Quantum Error Correcting Codes

    Science.gov (United States)

    Takagi, Ryuji; Yoder, Theodore; Chuang, Isaac

    If all the physical gates in a fault tolerant code construction have a failure probability below a certain value, the failure probability of the construction approaches zero after many concatenations. This value is called the threshold value of the code and lower bounds for it for various codes have been reported in the literature. However, these approaches do not take into account that the failure probability of each species of logical gate depends on that of many different species of physical gates, and that the distribution of logical failure probability depends on that of many different physical gates. How can we reconcile the interdependency of the failure probabilities of all the various species of gates? Direct simulation would be one of the possible ways to attack this question, but it would be difficult to be done at high concatenation levels because of the exponential growth of simulation time. Here, we deal with this question by instead considering a multidimensional space of the failure probabilities of the physical gates and study the set of points that approach zero error after a large number of concatenations. We present a way to obtain lower and upper bounds for the boundary of this set, what we call the threshold surface, given a particular code and constructions of logical gates. Our method uses only the logical failure probabilities after one concatenation, and moreover the running time of the algorithm scales linearly with respect to concatenation levels. We hope this will establish a reasonable goal for experiments to work towards a scalable quantum computer.

  12. Establishment of chondroitin B lyase-based analytical methods for sensitive and quantitative detection of dermatan sulfate in heparin.

    Science.gov (United States)

    Wu, Jingjun; Ji, Yang; Su, Nan; Li, Ye; Liu, Xinxin; Mei, Xiang; Zhou, Qianqian; Zhang, Chong; Xing, Xin-hui

    2016-06-25

    Dermatan sulfate (DS) is one of the hardest impurities to remove from heparin products due to their high structural similarity. The development of a sensitive and feasible method for quantitative detection of DS in heparin is essential to ensure the clinical safety of heparin pharmaceuticals. In the current study, based on the substrate specificity of chondroitin B lyase, ultraviolet spectrophotometric and strong anion-exchange high-performance liquid chromatographic methods were established for detection of DS in heparin. The former method facilitated analysis in heparin with DS concentrations greater than 0.1mgmL(-1) at 232nm, with good linearity, precision and recovery. The latter method allowed sensitive and accurate detection of DS at concentrations lower than 0.1mgmL(-1), exhibiting good linearity, precision and recovery. The linear range of DS detection using the latter method was between 0.01 and 0.5mgmL(-1).

  13. Highly specific and sensitive electrochemical genotyping via gap ligation reaction and surface hybridization detection.

    Science.gov (United States)

    Huang, Yong; Zhang, Yan-Li; Xu, Xiangmin; Jiang, Jian-Hui; Shen, Guo-Li; Yu, Ru-Qin

    2009-02-25

    This paper developed a novel electrochemical genotyping strategy based on gap ligation reaction with surface hybridization detection. This strategy utilized homogeneous enzymatic reactions to generate molecular beacon-structured allele-specific products that could be cooperatively annealed to capture probes stably immobilized on the surface via disulfide anchors, thus allowing ultrasensitive surface hybridization detection of the allele-specific products through redox tags in close proximity to the electrode. Such a unique biphasic architecture provided a universal methodology for incorporating enzymatic discrimination reactions in electrochemical genotyping with desirable reproducibility, high efficiency and no interferences from interficial steric hindrance. The developed technique was demonstrated to show intrinsic high sensitivity for direct genomic analysis, and excellent specificity with discriminativity of single nucleotide variations.

  14. Fabrication of pH sensitive nanovalves using smart surface coated nanopores

    Science.gov (United States)

    Nieto-Soto, A. M.; Diaz-Maldonado, D. K.; Rios Angarita, F. A.

    2017-01-01

    A pH sensitive nanovalve was fabricated using different smart surfaces covalently attached to an anodized aluminium oxide membrane (AAO). The smart surfaces were synthesized using a mixture of aliphatic and aminated silanes. Effect on the contact angle of the aliphatic silane chain length was evaluated. The smart surface, in conjunction with a nanoporous membrane, allowed the formation of a hydrophobic plug which controlled the transport of the molecule safranine depending on the pH of the solution. It was demonstrated that mixtures of butyl and methyl-trimethoxysilane with aminopropyl-trimethoxysilane were able to perform as effective nanovalves creating a plug that remained closed at pH>7 and opened up at pH<5.

  15. The influence of surface finishing methods on touch-sensitive reactions

    Science.gov (United States)

    Kukhta, M. S.; Sokolov, A. P.; Krauinsh, P. Y.; Kozlova, A. D.; Bouchard, C.

    2017-02-01

    This paper describes the modern technological development trends in jewelry design. In the jewelry industry, new trends, associated with the introduction of updated non-traditional materials and finishing techniques, are appearing. The existing information-oriented society enhances the visual aesthetics of new jewelry forms, decoration techniques (depth and surface), synthesis of different materials, which, all in all, reveal a bias towards positive effects of visual design. Today, the jewelry industry includes not only traditional techniques, but also such improved techniques as computer-assisted design, 3D-prototyping and other alternatives to produce an updated level of jewelry material processing. The authors present the specific features of ornamental pattern designing, decoration types (depth and surface) and comparative analysis of different approaches in surface finishing. Identifying the appearance or the effect of jewelry is based on proposed evaluation criteria, providing an advanced visual aesthetics basis is predicated on touch-sensitive responses.

  16. Immobilized fluorescent dyes for sensitive pH measurements on enamel surfaces with fiber optics

    Science.gov (United States)

    Rumphorst, A.; Seeger, Stefan; Duschner, H.

    1996-01-01

    Information on the pH directly on surfaces of dental enamel is an important aspect in research on tooth decay. As an alternative to pH-electrodes our approach to the problem is the optical determination of pH by pH sensitive fluorescent dyes immobilized to tooth surfaces. In this study a model for measuring pH either on aminated cellulose substrates or on enamel (in vitro) with a fluorescein type dye is presented. The experimental realization is a fiber optic sensor with a nitrogen-pumped dye laser system and photodiode for the detection of the emitted fluorescence light. The surface pH values in the range between 4 and 7 were derived from the ratios of the excitation bands at 490 nm and 460 nm.

  17. The validation of an analytical method for sulfentrazone residue determination in soil using liquid chromatography and a comparison of chromatographic sensitivity to millet as a bioindicator species.

    Science.gov (United States)

    de Oliveira, Marcelo Antonio; Pires, Fábio Ribeiro; Ferraço, Mariana; Belo, Alessandra Ferreira

    2014-07-28

    Commonly used herbicides, such as sulfentrazone, pose the risk of soil contamination due to their persistence, bioaccumulation and toxicity. Phytoremediation by green manure species has been tested using biomarkers, but analytical data are now required to confirm the extraction of sulfentrazone from soil. Thus, the present work was carried out to analyze sulfentrazone residues in soil based on liquid chromatography with a comparison of these values to the sensitivity of the bioindicator Pennisetum glaucum. The soil samples were obtained after cultivation of Crotalaria juncea and Canavalia ensiformis at four seeding densities and with three doses of sulfentrazone. The seedlings were collected into pots, at two different depths, after 75 days of phytoremediator sowing and then were used to determine the herbicide persistence in the soil. A bioassay with P. glaucum was carried out in the same pot. High-performance liquid chromatography (HPLC), using UV-diode array detection (HPLC/UV-DAD), was used to determine the herbicide residues. The HPLC determination was optimized and validated according to the parameters of precision, accuracy, linearity, limit of detection and quantification, robustness and specificity. The bioindicator P. glaucum was more sensitive to sulfentrazone than residue determination by HPLC. Changes in sulfentrazone concentration caused by green manure phytoremediation were accurately identified by the bioindicator. However, a true correlation between the size of the species and the analyte content was not identified.

  18. Preservatives and neutralizing substances in milk: analytical sensitivity of official specific and nonspecific tests, microbial inhibition effect, and residue persistence in milk

    Directory of Open Access Journals (Sweden)

    Livia Cavaletti Corrêa da Silva

    2015-09-01

    Full Text Available Milk fraud has been a recurring problem in Brazil; thus, it is important to know the effect of most frequently used preservatives and neutralizing substances as well as the detection capability of official tests. The objective of this study was to evaluate the analytical sensitivity of legislation-described tests and nonspecific microbial inhibition tests, and to investigate the effect of such substances on microbial growth inhibition and the persistence of detectable residues after 24/48h of refrigeration. Batches of raw milk, free from any contaminant, were divided into aliquots and mixed with different concentrations of formaldehyde, hydrogen peroxide, sodium hypochlorite, chlorine, chlorinated alkaline detergent, or sodium hydroxide. The analytical sensitivity of the official tests was 0.005%, 0.003%, and 0.013% for formaldehyde, hydrogen peroxide, and hypochlorite, respectively. Chlorine and chlorinated alkaline detergent were not detected by regulatory tests. In the tests for neutralizing substances, sodium hydroxide could not be detected when acidity was accurately neutralized. The yogurt culture test gave results similar to those obtained by official tests for the detection of specific substances. Concentrations of 0.05% of formaldehyde, 0.003% of hydrogen peroxide and 0.013% of sodium hypochlorite significantly reduced (P

  19. The Validation of an Analytical Method for Sulfentrazone Residue Determination in Soil Using Liquid Chromatography and a Comparison of Chromatographic Sensitivity to Millet as a Bioindicator Species

    Directory of Open Access Journals (Sweden)

    Marcelo Antonio de Oliveira

    2014-07-01

    Full Text Available Commonly used herbicides, such as sulfentrazone, pose the risk of soil contamination due to their persistence, bioaccumulation and toxicity. Phytoremediation by green manure species has been tested using biomarkers, but analytical data are now required to confirm the extraction of sulfentrazone from soil. Thus, the present work was carried out to analyze sulfentrazone residues in soil based on liquid chromatography with a comparison of these values to the sensitivity of the bioindicator Pennisetum glaucum. The soil samples were obtained after cultivation of Crotalaria juncea and Canavalia ensiformis at four seeding densities and with three doses of sulfentrazone. The seedlings were collected into pots, at two different depths, after 75 days of phytoremediator sowing and then were used to determine the herbicide persistence in the soil. A bioassay with P. glaucum was carried out in the same pot. High-performance liquid chromatography (HPLC, using UV-diode array detection (HPLC/UV-DAD, was used to determine the herbicide residues. The HPLC determination was optimized and validated according to the parameters of precision, accuracy, linearity, limit of detection and quantification, robustness and specificity. The bioindicator P. glaucum was more sensitive to sulfentrazone than residue determination by HPLC. Changes in sulfentrazone concentration caused by green manure phytoremediation were accurately identified by the bioindicator. However, a true correlation between the size of the species and the analyte content was not identified.

  20. Sensitivity of surface air temperature change to land use/cover types in China

    Institute of Scientific and Technical Information of China (English)

    YANG XuChao; ZHANG YiLi; LIU LinShan; ZHANG Wei; DING MingJun; WANG ZhaoFeng

    2009-01-01

    Using CRU high resolution grid observational temperature and ERA40 reanalysie surface air temperature data during 1960--1999, we investigated the sensitivity of surface air temperature change to land use/cover types in China by subtracting the reanalysis from the observed surface air temperature (observation minus reanalysis, OMR). The results show that there is a stable and systemic impact of land use/cover types on surface air temperature. The surface warming of each land use/cover type reacted differently to global warming. The OMR trends of unused land (≥0.17℃/decade), mainly comprised by sandy land, Gobi and bare rock gravel land, are obviously larger than those of the other land use/cover types. The OMR over grassland, farmland and construction land shows a moderate decadal a significant warming trend (0.06"C/decade). The overall assessment indicates that the surface warming is larger for areas that are barren and anthropogenically developed. The better the vegetation cover, the smaller the OMR warming trend. Responses of surface air temperature to land use/cover types with similar physical and chemical properties and biological processes have no significant difference. The surface air temperature would not react significantly until the intensity of land cover changes reach a certain degree. Within the same land use/cover type, areas in eastern China with intensive human activities exhibit larger warming trend. The results provide observational evidence for modeling research on the impact of land use/cover change on regional climate. Thus, projecting further surface climate of China in regional scale should not only take greenhouse gas increase into account, but also consider the impact of land use/cover types and land cover change.

  1. Sensitivity of surface air temperature change to land use/cover types in China

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Using CRU high resolution grid observational temperature and ERA40 reanalysis surface air temperature data during 1960-1999, we investigated the sensitivity of surface air temperature change to land use/cover types in China by subtracting the reanalysis from the observed surface air temperature (observation minus reanalysis, OMR). The results show that there is a stable and systemic impact of land use/cover types on surface air temperature. The surface warming of each land use/cover type reacted differently to global warming. The OMR trends of unused land (≥0.17℃/decade), mainly comprised by sandy land, Gobi and bare rock gravel land, are obviously larger than those of the other land use/cover types. The OMR over grassland, farmland and construction land shows a moderate decadal warming about 0.12℃ /decade, 0.10℃/decade, 0.12 ℃ /decade, respectively. Woodland areas do not show a significant warming trend (0.06 ℃ /decade). The overall assessment indicates that the surface warming is larger for areas that are barren and anthropogenically developed. The better the vegetation cover, the smaller the OMR warming trend. Responses of surface air temperature to land use/cover types with similar physical and chemical properties and biological processes have no significant difference. The surface air temperature would not react significantly until the intensity of land cover changes reach a certain degree. Within the same land use/cover type, areas in eastern China with intensive human activities exhibit larger warming trend. The results provide observational evidence for modeling research on the impact of land use/cover change on regional climate. Thus, projecting further surface climate of China in regional scale should not only take greenhouse gas increase into account, but also consider the impact of land use/cover types and land cover change.

  2. Analytical solutions for the surface response to small amplitude perturbations in boundary data in the shallow-ice-stream approximation

    Directory of Open Access Journals (Sweden)

    G. H. Gudmundsson

    2008-07-01

    Full Text Available New analytical solutions describing the effects of small-amplitude perturbations in boundary data on flow in the shallow-ice-stream approximation are presented. These solutions are valid for a non-linear Weertman-type sliding law and for Newtonian ice rheology. Comparison is made with corresponding solutions of the shallow-ice-sheet approximation, and with solutions of the full Stokes equations. The shallow-ice-stream approximation is commonly used to describe large-scale ice stream flow over a weak bed, while the shallow-ice-sheet approximation forms the basis of most current large-scale ice sheet models. It is found that the shallow-ice-stream approximation overestimates the effects of bed topography perturbations on surface profile for wavelengths less than about 5 to 10 ice thicknesses, the exact number depending on values of surface slope and slip ratio. For high slip ratios, the shallow-ice-stream approximation gives a very simple description of the relationship between bed and surface topography, with the corresponding transfer amplitudes being close to unity for any given wavelength. The shallow-ice-stream estimates for the timescales that govern the transient response of ice streams to external perturbations are considerably more accurate than those based on the shallow-ice-sheet approximation. In particular, in contrast to the shallow-ice-sheet approximation, the shallow-ice-stream approximation correctly reproduces the short-wavelength limit of the kinematic phase speed given by solving a linearised version of the full Stokes system. In accordance with the full Stokes solutions, the shallow-ice-sheet approximation predicts surface fields to react weakly to spatial variations in basal slipperiness with wavelengths less than about 10 to 20 ice thicknesses.

  3. Surface energy balance sensitivity to meteorological variability on Haig Glacier, Canadian Rocky Mountains

    Science.gov (United States)

    Ebrahimi, Samaneh; Marshall, Shawn J.

    2016-11-01

    Energy exchanges between the atmosphere and the glacier surface control the net energy available for snow and ice melt. This paper explores the response of a midlatitude glacier in the Canadian Rocky Mountains to daily and interannual variations in the meteorological parameters that govern the surface energy balance. We use an energy balance model to run sensitivity tests to perturbations in temperature, specific humidity, wind speed, incoming shortwave radiation, glacier surface albedo, and winter snowpack depth. Variables are perturbed (i) in isolation, (ii) including internal feedbacks, and (iii) with co-evolution of meteorological perturbations, derived from the North American regional climate reanalysis (NARR) over the period 1979-2014. Summer melt at this site has the strongest sensitivity to interannual variations in temperature, albedo, and specific humidity, while fluctuations in cloud cover, wind speed, and winter snowpack depth have less influence. Feedbacks to temperature forcing, in particular summer albedo evolution, double the melt sensitivity to a temperature change. When meteorological perturbations covary through the NARR forcing, summer temperature anomalies remain important in driving interannual summer energy balance and melt variability, but they are reduced in importance relative to an isolated temperature forcing. Covariation of other variables (e.g., clear skies, giving reduced incoming longwave radiation) may be partially compensating for the increase in temperature. The methods introduced in this paper provide a framework that can be extended to compare the sensitivity of glaciers in different climate regimes, e.g., polar, maritime, or tropical environments, and to assess the importance of different meteorological parameters in different regions.

  4. Sensitivity of biogenic volatile organic compounds to land surface parameterizations and vegetation distributions in California

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Chun; Huang, Maoyi; Fast, Jerome D.; Berg, Larry K.; Qian, Yun; Guenther , A.; Gu, Dasa; Shrivastava, ManishKumar B.; Liu, Ying; Walters, Stacy; Pfister, G.; Jin, Jiming; Shilling, John E.; Warneke, Carsten

    2016-05-27

    Current climate models still have large uncertainties 24 in estimating biogenic trace gases, which can significantly affect atmospheric chemistry and secondary aerosol formation that ultimately influences air quality and aerosol radiative forcing. These uncertainties result from many factors, including uncertainties in land-surface processes and specification of vegetation types, both of which can affect the simulated near-surface fluxes of biogenic volatile organic compounds (BVOCs). In this study, the latest version of Model of Emissions of Gases and Aerosols from Nature MEGAN (MEGAN v2.1) is coupled within the land surface parameterization CLM4 in the Weather Research and Forecasting model with chemistry (WRF-Chem). In this implement, MEGAN v2.1 shares a consistent vegetation map with CLM4 for estimating BVOC emissions. This is unlike MEGAN v2.0 in the public version of WRF-Chem that uses a standalone vegetation map that differs from what is used by land surface parameterizations. This improved modeling framework is used to investigate the impact of two land surface parameterizations, CLM4 and Noah, on BVOCs and examine the sensitivity of BVOCs to vegetation distributions in California. The measurements collected during the Carbonaceous Aerosol and Radiative Effects Study (CARES) and the California Nexus of Air Quality and Climate Experiment (CalNex) conducted during June of 2010 provide an opportunity to evaluate the simulated BVOCs. Sensitivity experiments show that land surface parameterizations do influence the simulated BVOCs, but that impact is much smaller than that of vegetation distributions. This study indicates that more effort is needed to obtain the most appropriate and accurate land cover datasets for climate and air quality models in terms of simulating BVOCs, oxidant chemistry, and consequently secondary organic aerosol formation.

  5. Enhanced fluorescence sensitivity by coupling yttrium-analyte complexes and three-way fast high-performance liquid chromatography data modeling

    Energy Technology Data Exchange (ETDEWEB)

    Alcaraz, Mirta R.; Culzoni, María J., E-mail: mculzoni@fbcb.unl.edu.ar; Goicoechea, Héctor C., E-mail: hgoico@fbcb.unl.edu.ar

    2016-01-01

    The present study reports a sensitive chromatographic method for the analysis of seven fluoroquinolones (FQs) in environmental water samples, by coupling yttrium-analyte complex and three-way chromatographic data modeling. This method based on the use of HPLC-FSFD does not require complex or tedious sample treatments or enrichment processes before the analysis, due to the significant fluorescence increments of the analytes reached by the presence of Y{sup 3+}. Enhancement achieved for the FQs signals obtained after Y{sup 3+} addition reaches 103- to 1743-fold. Prediction results corresponding to the application of MCR-ALS to the validation set showed relative error of prediction (REP%) values below 10% in all cases. A recovery study that includes the simultaneous determination of the seven FQs in three different environmental aqueous matrices was conducted. The recovery studies assert the efficiency and the accuracy of the proposed method. The LOD values calculated are in the order of part per trillion (below 0.5 ng mL{sup −1} for all the FQs, except for enoxacin). It is noteworthy to mention that the method herein proposed, which does not include pre-concentration steps, allows reaching LOD values in the same order of magnitude than those achieved by more sophisticated methods based on SPE and UHPLC-MS/MS. - Highlights: • Highly sensitive method for the analysis of seven fluoroquinolones. • Coupling of yttrium-analyte complex and three-way modeling. • Complex or tedious sample treatments or enrichment processes are nor required. • Accuracy on the quantitation of fluoroquinolones in real water river samples.

  6. A microwave resonator for limiting depth sensitivity for electron paramagnetic resonance spectroscopy of surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Sidabras, Jason W.; Varanasi, Shiv K.; Hyde, James S. [Department of Biophysics, Medical College of Wisconsin, Milwaukee, Wisconsin 53211 (United States); Mett, Richard R. [Department of Biophysics, Medical College of Wisconsin, Milwaukee, Wisconsin 53211 (United States); Department of Physics and Chemistry, Milwaukee School of Engineering, Milwaukee, Wisconsin 53202 (United States); Swarts, Steven G. [Department of Radiation Oncology, University of Florida, Gainesville, Florida, 32610 (United States); Swartz, Harold M. [Department of Radiology, Geisel Medical School at Dartmouth, Hanover, New Hampshire 03755 (United States)

    2014-10-15

    A microwave Surface Resonator Array (SRA) structure is described for use in Electron Paramagnetic Resonance (EPR) spectroscopy. The SRA has a series of anti-parallel transmission line modes that provides a region of sensitivity equal to the cross-sectional area times its depth sensitivity, which is approximately half the distance between the transmission line centers. It is shown that the quarter-wave twin-lead transmission line can be a useful element for design of microwave resonators at frequencies as high as 10 GHz. The SRA geometry is presented as a novel resonator for use in surface spectroscopy where the region of interest is either surrounded by lossy material, or the spectroscopist wishes to minimize signal from surrounding materials. One such application is in vivo spectroscopy of human finger-nails at X-band (9.5 GHz) to measure ionizing radiation dosages. In order to reduce losses associated with tissues beneath the nail that yield no EPR signal, the SRA structure is designed to limit depth sensitivity to the thickness of the fingernail. Another application, due to the resonator geometry and limited depth penetration, is surface spectroscopy in coating or material science. To test this application, a spectrum of 1.44 μM of Mg{sup 2+} doped polystyrene 1.1 mm thick on an aluminum surface is obtained. Modeling, design, and simulations were performed using Wolfram Mathematica (Champaign, IL; v. 9.0) and Ansys High Frequency Structure Simulator (HFSS; Canonsburg, PA; v. 15.0). A micro-strip coupling circuit is designed to suppress unwanted modes and provide a balanced impedance transformation to a 50 Ω coaxial input. Agreement between simulated and experimental results is shown.

  7. A microwave resonator for limiting depth sensitivity for electron paramagnetic resonance spectroscopy of surfaces

    Science.gov (United States)

    Sidabras, Jason W.; Varanasi, Shiv K.; Mett, Richard R.; Swarts, Steven G.; Swartz, Harold M.; Hyde, James S.

    2014-10-01

    A microwave Surface Resonator Array (SRA) structure is described for use in Electron Paramagnetic Resonance (EPR) spectroscopy. The SRA has a series of anti-parallel transmission line modes that provides a region of sensitivity equal to the cross-sectional area times its depth sensitivity, which is approximately half the distance between the transmission line centers. It is shown that the quarter-wave twin-lead transmission line can be a useful element for design of microwave resonators at frequencies as high as 10 GHz. The SRA geometry is presented as a novel resonator for use in surface spectroscopy where the region of interest is either surrounded by lossy material, or the spectroscopist wishes to minimize signal from surrounding materials. One such application is in vivo spectroscopy of human finger-nails at X-band (9.5 GHz) to measure ionizing radiation dosages. In order to reduce losses associated with tissues beneath the nail that yield no EPR signal, the SRA structure is designed to limit depth sensitivity to the thickness of the fingernail. Another application, due to the resonator geometry and limited depth penetration, is surface spectroscopy in coating or material science. To test this application, a spectrum of 1.44 μM of Mg2+ doped polystyrene 1.1 mm thick on an aluminum surface is obtained. Modeling, design, and simulations were performed using Wolfram Mathematica (Champaign, IL; v. 9.0) and Ansys High Frequency Structure Simulator (HFSS; Canonsburg, PA; v. 15.0). A micro-strip coupling circuit is designed to suppress unwanted modes and provide a balanced impedance transformation to a 50 Ω coaxial input. Agreement between simulated and experimental results is shown.

  8. A microwave resonator for limiting depth sensitivity for electron paramagnetic resonance spectroscopy of surfaces.

    Science.gov (United States)

    Sidabras, Jason W; Varanasi, Shiv K; Mett, Richard R; Swarts, Steven G; Swartz, Harold M; Hyde, James S

    2014-10-01

    A microwave Surface Resonator Array (SRA) structure is described for use in Electron Paramagnetic Resonance (EPR) spectroscopy. The SRA has a series of anti-parallel transmission line modes that provides a region of sensitivity equal to the cross-sectional area times its depth sensitivity, which is approximately half the distance between the transmission line centers. It is shown that the quarter-wave twin-lead transmission line can be a useful element for design of microwave resonators at frequencies as high as 10 GHz. The SRA geometry is presented as a novel resonator for use in surface spectroscopy where the region of interest is either surrounded by lossy material, or the spectroscopist wishes to minimize signal from surrounding materials. One such application is in vivo spectroscopy of human finger-nails at X-band (9.5 GHz) to measure ionizing radiation dosages. In order to reduce losses associated with tissues beneath the nail that yield no EPR signal, the SRA structure is designed to limit depth sensitivity to the thickness of the fingernail. Another application, due to the resonator geometry and limited depth penetration, is surface spectroscopy in coating or material science. To test this application, a spectrum of 1.44 μM of Mg(2+) doped polystyrene 1.1 mm thick on an aluminum surface is obtained. Modeling, design, and simulations were performed using Wolfram Mathematica (Champaign, IL; v. 9.0) and Ansys High Frequency Structure Simulator (HFSS; Canonsburg, PA; v. 15.0). A micro-strip coupling circuit is designed to suppress unwanted modes and provide a balanced impedance transformation to a 50 Ω coaxial input. Agreement between simulated and experimental results is shown.

  9. New Analytical Methods for the Surface/ Interface and the Micro-Structures in Advanced Nanocomposite Materials by Synchrotron Radiation

    Directory of Open Access Journals (Sweden)

    K. Nakamae

    2010-12-01

    Full Text Available Analytical methods of surface/interface structure and micro-structure in advanced nanocomposite materials by using the synchrotron radiation are introduced. Recent results obtained by the energy-tunable and highly collimated brilliant X-rays, in-situ wide angle/small angle X-ray diffraction with high accuracy are reviewed. It is shown that small angle X-ray scattering is one of the best methods to characterize nanoparticle dispersibility, filler aggregate/agglomerate structures and in-situ observation of hierarchical structure deformation in filled rubber under cyclic stretch. Grazing Incidence(small and wide angle X-ray Scattering are powerful to analyze the sintering process of metal nanoparticle by in-situ observation as well as the orientation of polymer molecules and crystalline orientation at very thin surface layer (ca 7nm of polymer film. While the interaction and conformation of adsorbed molecule at interface can be investigated by using high energy X-ray XPS with Enough deep position (ca 9 micron m.

  10. Solution Process Synthesis of High Aspect Ratio ZnO Nanorods on Electrode Surface for Sensitive Electrochemical Detection of Uric Acid

    Science.gov (United States)

    Ahmad, Rafiq; Tripathy, Nirmalya; Ahn, Min-Sang; Hahn, Yoon-Bong

    2017-04-01

    This study demonstrates a highly stable, selective and sensitive uric acid (UA) biosensor based on high aspect ratio zinc oxide nanorods (ZNRs) vertical grown on electrode surface via a simple one-step low temperature solution route. Uricase enzyme was immobilized on the ZNRs followed by Nafion covering to fabricate UA sensing electrodes (Nafion/Uricase-ZNRs/Ag). The fabricated electrodes showed enhanced performance with attractive analytical response, such as a high sensitivity of 239.67 μA cm-2 mM-1 in wide-linear range (0.01-4.56 mM), rapid response time (~3 s), low detection limit (5 nM), and low value of apparent Michaelis-Menten constant (Kmapp, 0.025 mM). In addition, selectivity, reproducibility and long-term storage stability of biosensor was also demonstrated. These results can be attributed to the high aspect ratio of vertically grown ZNRs which provides high surface area leading to enhanced enzyme immobilization, high electrocatalytic activity, and direct electron transfer during electrochemical detection of UA. We expect that this biosensor platform will be advantageous to fabricate ultrasensitive, robust, low-cost sensing device for numerous analyte detection.

  11. Mismatches in Phenology of Birds and Their Food Due to Climate Change: Big Data, Analytical Challenges, and Scale Sensitivity

    Science.gov (United States)

    Mayor, S.; Andrew, M. E.; Elmendorf, S.; Guralnick, R. P.; Minor, E. S.; Schneider, D.; Tersigni, V.; Thibault, K. M.; Tingley, M. W.; Withey, J. C.

    2013-12-01

    We explored analytical issues that come with challenging ecological concepts against large data sets. As an example, we examined the expected mismatch between the phenology (annual timing) of endothermic migratory birds with the phenology of primarily ectothermic (degree-day dependent) food resources. We hypothesized that bird phenology, which is often tightly hormonally tied to day length cues would be increasing out of phase the phenology of their food resources, due to increases in both mean and variability of spring temperatures. Specifically, we tested whether bird populations have been able to match their migration times to the timing of spring 'greenup', when food resources become plentiful. If not, we also test if suboptimal migration timing resulted in negative fitness consequences for individual bird species? We expected (1) a mismatch between optimal migration time and observed migration time; (2) greater variation in mean timing of ectothermic prey resources than migratory arrival of endothermic birds; (3) higher per capita survival and reproduction of species with the smallest optimal/observed migration timing mismatch. We tested these expectations with rich datasets extensive in both time and space. We brought together nearly a decade of migratory arrival records for over 100 bird species across the continental U.S. (eBird) with remotely sensed (MODIS) time of spring greenup, which is concurrent with insect abundance, and survival and reproduction estimates for each bird species (MAPS). In testing these questions with large data sets, we encountered several challenges. First, selecting the spatial scale(s) of analyses involve a priori estimation of scale(s) at which birds select food resources, and mismatches depend on analytical scale. To assess a mismatch in phenology (between birds and food), we attempted to minimize a mismatch in scales (between analyses and phenomena). Second, forming causal linkages between variables relied on previous

  12. Highly sensitive sensors based on magneto-optical surface plasmon resonance in Ag/CeYIG heterostructures

    Directory of Open Access Journals (Sweden)

    Jun Qin

    2015-01-01

    Full Text Available In this paper we present a new magneto-optical surface plasmon resonance (MOSPR sensor using a dielectric magneto-optical thin film of Ce1Y 2Fe5O12 (CeYIG and a metallic film of Ag. We demonstrate that by combining the low optical loss of Ag (ε =-62.485+4.331i and the strong magneto-optical effect of CeYIG (ΦF = 2 × 104 deg/cm at ∼1000 nm wavelength, a high figure of merit (FoM for index sensing can be achieved. The device shows a factor of 20 improvement in the index resolution in comparison with ferromagnetic metal based MOSPR sensors at the same wavelength. By carrying out both analytical and numerical simulations, an optimized Ag/CeYIG MOSPR structure with the highest index sensitivity is achieved at the incident light wavelength of 1160 nm and the CeYIG thickness of 25 nm. The enhanced resolution of the DMOSPR sensor has been attributed to both the field enhancement at the sensing interface due to the high index of CeYIG films and, the high magneto-optical figure of merit of the CeYIG near infrared wavelength range.

  13. The BetaCage, an ultra-sensitive screener for surface contamination

    CERN Document Server

    Bunker, R; Bowles, M A; Golwala, S R; Grant, D R; Kos, M; Nelson, R H; Schnee, R W; Rider, A; Wang, B; Zahn, A

    2014-01-01

    Material screening for identifying low-energy electron emitters and alpha-decaying isotopes is now a prerequisite for rare-event searches (e.g., dark-matter direct detection and neutrinoless double-beta decay) for which surface radiocontamination has become an increasingly important background. The BetaCage, a gaseous neon time-projection chamber, is a proposed ultra-sensitive (and nondestructive) screener for alpha- and beta-emitting surface contaminants to which existing screening facilities are insufficiently sensitive. Sensitivity goals are 0.1 betas per keV-m$^2$-day and 0.1 alphas per m$^2$-day, with the former limited by Compton scattering of photons in the screening samples and (thanks to tracking) the latter expected to be signal-limited; radioassays and simulations indicate backgrounds from detector materials and radon daughters should be subdominant. We report on details of the background simulations and detector design that provide the discrimination, shielding, and radiopurity necessary to reach ...

  14. Synthesis of biocompatible and highly photoluminescent nitrogen doped carbon dots from lime: Analytical applications and optimization using response surface methodology

    Energy Technology Data Exchange (ETDEWEB)

    Barati, Ali [Faculty of Chemistry, Institute for Advanced Studies in Basic Sciences, Zanjan (Iran, Islamic Republic of); Shamsipur, Mojtaba, E-mail: mshamsipur@yahoo.com [Department of Chemistry, Razi University, Kermanshah (Iran, Islamic Republic of); Arkan, Elham [Nano Drug Delivery Research Center Kermanshah University of Medical Sciences, Kermanshah (Iran, Islamic Republic of); Hosseinzadeh, Leila [Novel Drug Delivery Research Center, Faculty of Pharmacy, Kermanshah University of Medical Sciences, Kermanshah (Iran, Islamic Republic of); Abdollahi, Hamid, E-mail: abd@iasbs.ac.ir [Faculty of Chemistry, Institute for Advanced Studies in Basic Sciences, Zanjan (Iran, Islamic Republic of)

    2015-02-01

    Herein, a facile hydrothermal treatment of lime juice to prepare biocompatible nitrogen-doped carbon quantum dots (N-CQDs) in the presence of ammonium bicarbonate as a nitrogen source has been presented. The resulting N-CQDs exhibited excitation and pH independent emission behavior; with the quantum yield (QY) up to 40%, which was several times greater than the corresponding value for CQDs with no added nitrogen source. The N-CQDs were applied as a fluorescent probe for the sensitive and selective detection of Hg{sup 2+} ions with a detection limit of 14 nM. Moreover, the cellular uptake and cytotoxicity of N-CQDs at different concentration ranges from 0.0 to 0.8 mg/ml were investigated by using PC12 cells as a model system. Response surface methodology was used for optimization and systematic investigation of the main variables that influence the QY, including reaction time, reaction temperature, and ammonium bicarbonate weight. - Highlights: • High fluorescent N-doped CQDs from lime juice have been prepared. • Response surface methodology was used to optimize and model the main factors. • N-doped CQDs were used in the selective and sensitive detection of Hg(II). • The biocompatibility of prepared N-doped CQDs was conformed using PC12 cells.

  15. [Detection of anti-ENA autoantibodies in patients with systemic connective tissue diseases. Analytical variability and diagnostic sensitivity of 4 methods].

    Science.gov (United States)

    Villalta, D; Bizzaro, N; Tonutti, E; Visentin, D; Manoni, F; Piazza, A; Toffolo, L; Rizzotti, P; Clemen, P; Pradella, M; Bassetti, D; Tozzoli, R

    1999-11-01

    This study was designed to assess the analytical sensitivity and rate of agreement between commercial methods and reagents, among the most used in Italy for the detection of autoantibodies to extractable nuclear antigens (ENA). Sixty-eight serum samples from patients with clinically diagnosed systemic rheumatic diseases were aliquoted and distributed to 4 hospital laboratories; three ELISA (Elias, Shield, Inova) and 1 immunoblot method (Euroimmun) were used. Overall agreement between the test reagents, for each anti-ENA specificity, was 69.1% for Ro/SSA, 83.3% for La/SSB, 70.6% for RNP, 73.5% for Sm, 91.1% for Jo1, and 82.3% for Scl70. Lack of specificity (i.e., false positive reactions) was the most important cause of low concordance. When the data were analysed according to the clinical diagnosis, total agreement and specificity improved. However, a significant difference in terms of sensitivity was observed in the SLE group (30 sera) for RNP (positivity ranged from 20% to 43%) and for Sm (from 7% to 37%), and in the Sjögren's syndrome group (13 sera) for anti-La/SSB (from 8% to 38%). Comparable data were obtained for anti-Ro/SSA (from 70% to 77%) both in the SLE and the Sjögren's syndrome group. Sensitivity of all 4 reagents was good in detecting anti-Scl70 autoantibodies in the 8 patients with diffuse systemic sclerosis, as well as anti-Jo1 autoantibody in the 5 polymyositis patients, with a 100% and a 95% agreement, respectively. These data suggest the need of a better standardization of commercial reagents and analytical procedures, and the opportunity that every laboratory should perform anti-ENA determination by at least two different methods, since none of the methods tested was completely reliable in detecting all anti-ENA autoantibody specificities.

  16. Assessing the near surface sensitivity of SCIAMACHY atmospheric CO2 retrieved using (FSI WFM-DOAS

    Directory of Open Access Journals (Sweden)

    N. Vinnichenko

    2007-02-01

    Full Text Available Satellite observations of atmospheric CO2 offer the potential to identify regional carbon surface sources and sinks and to investigate carbon cycle processes. The extent to which satellite measurements are useful however, depends on the near surface sensitivity of the chosen sensor. In this paper, the capability of the SCIAMACHY instrument on board ENVISAT, to observe lower tropospheric and surface CO2 variability is examined. To achieve this, atmospheric CO2 retrieved from SCIAMACHY near infrared (NIR spectral measurements, using the Full Spectral Initiation (FSI WFM-DOAS algorithm, is compared to in situ aircraft observations over Siberia and additionally to tower and surface CO2 data over Mongolia, Europe and North America. Preliminary validation of daily averaged SCIAMACHY/FSI CO2 against ground based Fourier Transform Spectrometer (FTS column measurements made at Park Falls, reveal a negative bias of about −2.0% for collocated measurements within ±1.0degree of the site. However, at this spatial threshold SCIAMACHY can only capture the variability of the FTS observations at monthly timescales. To observe day to day variability of the FTS observations, the collocation limits must be increased. Furthermore, comparisons to in-situ CO2 observations demonstrate that SCIAMACHY is capable of observing lower tropospheric variability on (at least monthly timescales. Out of seventeen time series comparisons, eleven have correlation coefficients of 0.7 or more, and have similar seasonal cycle amplitudes. Additional evidence of the near surface sensitivity of SCIAMACHY, is provided through the significant correlation of FSI derived CO2 with MODIS vegetation indices at over twenty selected locations in the United States. The SCIAMACHY/MODIS comparison reveals that at many of the sites, the amount of CO2 variability is coincident with the amount of vegetation activity. It is evident, from this analysis, that SCIAMACHY therefore has the potential to

  17. Assessing the near surface sensitivity of SCIAMACHY atmospheric CO2 retrieved using (FSI WFM-DOAS

    Directory of Open Access Journals (Sweden)

    N. Vinnichenko

    2007-07-01

    Full Text Available Satellite observations of atmospheric CO2 offer the potential to identify regional carbon surface sources and sinks and to investigate carbon cycle processes. The extent to which satellite measurements are useful however, depends on the near surface sensitivity of the chosen sensor. In this paper, the capability of the SCIAMACHY instrument on board ENVISAT, to observe lower tropospheric and surface CO2 variability is examined. To achieve this, atmospheric CO2 retrieved from SCIAMACHY near infrared (NIR spectral measurements, using the Full Spectral Initiation (FSI WFM-DOAS algorithm, is compared to in-situ aircraft observations over Siberia and additionally to tower and surface CO2 data over Mongolia, Europe and North America. Preliminary validation of daily averaged SCIAMACHY/FSI CO2 against ground based Fourier Transform Spectrometer (FTS column measurements made at Park Falls, reveal a negative bias of about −2.0% for collocated measurements within ±1.0° of the site. However, at this spatial threshold SCIAMACHY can only capture the variability of the FTS observations at monthly timescales. To observe day to day variability of the FTS observations, the collocation limits must be increased. Furthermore, comparisons to in-situ CO2 observations demonstrate that SCIAMACHY is capable of observing a seasonal signal that is representative of lower tropospheric variability on (at least monthly timescales. Out of seventeen time series comparisons, eleven have correlation coefficients of 0.7 or more, and have similar seasonal cycle amplitudes. Additional evidence of the near surface sensitivity of SCIAMACHY, is provided through the significant correlation of FSI derived CO2 with MODIS vegetation indices at over twenty selected locations in the United States. The SCIAMACHY/MODIS comparison reveals that at many of the sites, the amount of CO2 variability is coincident with the amount of vegetation activity. The presented analysis suggests that

  18. Highly sensitive graphene biosensor by monomolecular self-assembly of receptors on graphene surface

    Science.gov (United States)

    Kim, Ji Eun; No, Young Hyun; Kim, Joo Nam; Shin, Yong Seon; Kang, Won Tae; Kim, Young Rae; Kim, Kun Nyun; Kim, Yong Ho; Yu, Woo Jong

    2017-05-01

    Graphene has attracted a great deal of interest for applications in bio-sensing devices because of its ultra-thin structure, which enables strong electrostatic coupling with target molecules, and its excellent electrical mobility promising for ultra-fast sensing speeds. However, thickly stacked receptors on the graphene's surface interrupts electrostatic coupling between graphene and charged biomolecules, which can reduce the sensitivity of graphene biosensors. Here, we report a highly sensitive graphene biosensor by the monomolecular self-assembly of designed peptide protein receptors. The graphene channel was non-covalently functionalized using peptide protein receptors via the π-π interaction along the graphene's Bravais lattice, allowing ultra-thin monomolecular self-assembly through the graphene lattice. In thickness dependent characterization, a graphene sensor with a monomolecular receptor (thickness less than 3 nm) showed five times higher sensitivity and three times higher voltage shifts than graphene sensors with thick receptor stacks (thicknesses greater than 20 nm), which is attributed to excellent gate coupling between graphene and streptavidin via an ultrathin receptor insulator. In addition to having a fast-inherent response time (less than 0.6 s) based on fast binding speed between biotin and streptavidin, our graphene biosensor is a promising platform for highly sensitive real-time monitoring of biomolecules with high spatiotemporal resolution.

  19. Highly sensitive surface plasmon resonance sensor utilizing a long period grating with photosensitive cladding.

    Science.gov (United States)

    Li, Zhihong; Chen, Tao; Zhang, Zhaogang; Zhou, Yanming; Li, Dan; Xie, Zhong

    2016-02-20

    In this study, we propose and investigate a novel grating-assisted surface plasmon resonance (SPR) platform based on a silver coated long period fiber grating having a photosensitive cladding (C-LPFG). We show that the SPR mode is transited from the higher EH mode with an effective refractive index (ERI) close to that of the surrounding refractive index (SRI) and is highly sensitive to a change in the SRI. Compared with a conventional SPR sensor, a much higher sensitivity is obtained for the novel C-LPFG-based SPR sensor. The sensitivity can be further improved by reducing the fiber diameter. The numerical results show that the highest local sensitivity, which can be as high as ∼4900  nm/RIU, and the corresponding resolution of ∼2.04×10(-6)  RIU are achieved for the reduced silver coated C-LPFG sensor. Moreover, the Q-factor and the figure of merit exhibit better characteristics than those of the conventional LPFG-based SPR sensor. Our findings provide insight into the C-LPFG-based SPR platform being a potentially important area to explore for biochemical sensing.

  20. Position-sensitive radiation monitoring (surface contamination monitor). Innovative technology summary report

    Energy Technology Data Exchange (ETDEWEB)

    1999-06-01

    The Shonka Research Associates, Inc. Position-Sensitive Radiation Monitor both detects surface radiation and prepares electronic survey map/survey report of surveyed area automatically. The electronically recorded map can be downloaded to a personal computer for review and a map/report can be generated for inclusion in work packages. Switching from beta-gamma detection to alpha detection is relatively simple and entails moving a switch position to alpha and adjusting the voltage level to an alpha detection level. No field calibration is required when switching from beta-gamma to alpha detection. The system can be used for free-release surveys because it meets the federal detection level sensitivity limits requires for surface survey instrumentation. This technology is superior to traditionally-used floor contamination monitor (FCM) and hand-held survey instrumentation because it can precisely register locations of radioactivity and accurately correlate contamination levels to specific locations. Additionally, it can collect and store continuous radiological data in database format, which can be used to produce real-time imagery as well as automated graphics of survey data. Its flexible design can accommodate a variety of detectors. The cost of the innovative technology is 13% to 57% lower than traditional methods. This technology is suited for radiological surveys of flat surfaces at US Department of Energy (DOE) nuclear facility decontamination and decommissioning (D and D) sites or similar public or commercial sites.

  1. Mitigating the surface urban heat island: Mechanism study and sensitivity analysis

    Science.gov (United States)

    Meng, Chunlei

    2017-08-01

    In a surface urban heat island (SUHI), the urban land surface temperature (LST) is usually higher than the temperature of the surrounding rural areas due to human activities and surface characteristics. Because a SUHI has many adverse impacts on urban environment and human health, SUHI mitigation strategies are very important. This paper investigates the mechanism of a SUHI based on the basic physical laws that control the formation of a SUHI; five mitigation strategies are proposed, namely: sprinkling and watering; paving a pervious surface; reducing the anthropogenic heat (AH) release; using a "white roof"; increasing the fractional vegetation cover or leaf area index (LAI). To quantify the effect of these mitigation strategies, 26 sets of experiments are designed and implemented by running the integrated urban land model (IUM). The results of the sensitivity analysis indicate that sprinkling and watering is an effective measure for mitigating a SUHI for an entire day. Decreasing the AH release is also useful for both night- and daytime SUHI mitigation; however, the cooling extent is proportional to the diurnal cycle of AH. Increasing the albedo can reduce the LST in the daytime, especially when the solar radiation is significant; the cooling extent is approximately proportional to the diurnal cycle of the net radiation. Increasing the pervious surface percentage can mitigate the SUHI especially in the daytime. Increasing the fractional vegetation cover can mitigate the SUHI in the daytime but may aggravate the SUHI at night.

  2. Estimating cloud optical thickness and associated surface UV irradiance from SEVIRI by implementing a semi-analytical cloud retrieval algorithm

    Directory of Open Access Journals (Sweden)

    P. Pandey

    2012-01-01

    Full Text Available In this paper, we describe the implementation of the Semi-Analytical Cloud Retrieval Algorithm (SACURA, to obtain scaled cloud optical thickness (SCOT from satellite imagery acquired with the SEVIRI instrument and surface UV irradiance levels. In estimation of SCOT particular care is given to the proper specification of the background (i.e., cloud-free spectral albedo and the retrieval of the cloud water phase from reflectance ratios in SEVIRI's 0.6 μm and 1.6 μm spectral bands. The SACURA scheme is then applied to daytime SEVIRI imagery over Europe, for the month of June 2006, at 15-min time increments. The resulting SCOT fields are compared with values obtained by the CloudSat experimental satellite mission, yielding a negligible bias, correlation coefficients ranging from 0.51 to 0.78, and a root mean square difference of 1 to 2 SCOT increments. These findings compare favourably to results from similar intercomparison exercises reported in the literature. Based on the retrieved SCOT from SEVIRI and radiative transfer modelling approach, simple parameterisations are proposed to estimate the surface UV-A and UV-B irradiance. The validation of the modelled UV-A and UV-B irradiance against the measurements over two Belgian stations, Redu and Ostend, indicate good agreement with the high correlation, index of agreement and low bias. The SCOT fields estimated by implementing SACURA on imagery from geostationary satellite are reliable and its impact on surface UV irradiance levels is well produced.

  3. Molecularly imprinted polymers for highly sensitive detection of morphine using surface plasmon resonance spectroscopy

    Institute of Scientific and Technical Information of China (English)

    Hong Xia Hao; Hong Zhou; Jing Chang; Jun Zhu; Tian Xin Wei

    2011-01-01

    Molecular imprinting technology is applied in surface plasmon resonance spectroscopy for highly sensitive and selective detection of morphine (MO). As SPR-based sensor of MO, the preparation of molecular imprinted polymer is as follows: methacrylic acids (MAA), ethylene glycol dimethacrylate (EGDMA), azodiisobutyronitrile (AIBN) were used as functional monomer, cross-linker and initiator, respectively. The experiment results showed that morphine imprinted polymer had the performance of high sensitivity and specificity, i.e. the relative signal of SPR response was proportional to the concentration of morphine in acetonitrile in the range of 10-9 mol/L to 10-6mol/L (1 ppb-1 ppm) with LOD of 10-10mol/L, and MO was distinguished from its analogs, such as codeine.

  4. Highly sensitive detection of zearalenone in feed samples using competitive surface-enhanced Raman scattering immunoassay.

    Science.gov (United States)

    Liu, Jianzhi; Hu, Yongjun; Zhu, Guichi; Zhou, Xiaoming; Jia, Li; Zhang, Tao

    2014-08-20

    Accurate and quantitative analysis of mycotoxin (such as zearalenone) is particularly imperative in the field of food safety and animal husbandry. Here, we develop a sensitive and specific method for zearalenone detection using competitive surface-enhanced Raman scattering (SERS) immunoassay. In this assay, a functional gold nanoparticle was labeled with the Raman reporter and the zearalenone antibody, and a modified substrate was assembled with the zearalenone-bovine serum albumin. With the addition of free zearalenone, the competitive immune reaction between free zearalenone and zearalenone-bovine serum albumin was initiated for binding with zearalenone antibody labeled on gold nanoparticle, resulting in the change of SERS signal intensity. The proposed method exhibits high sensitivity with a detection limit of 1 pg/mL and a wide dynamic range from 1 to 1000 pg/mL. Furthermore, this method can be further applied to analyze the multiple natural feed samples contaminated with zearalenone, holding great potential for real sample detection.

  5. A high sensitivity wireless mass-loading surface acoustic wave DNA biosensor

    Science.gov (United States)

    Cai, Hua-Lin; Yang, Yi; Zhang, Yi-Han; Zhou, Chang-Jian; Guo, Cang-Ran; Liu, Jing; Ren, Tian-Ling

    2014-03-01

    In this paper, a surface acoustic wave (SAW) biosensor with gold delay area on LiNbO3 substrate detecting DNA sequences is proposed. By well-designed device parameters of the SAW sensor, it achieves a high performance for highly sensitive detection of target DNA. In addition, an effective biological treatment method for DNA immobilization and abundant experimental verification of the sensing effect have made it a reliable device in DNA detection. The loading mass of the probe and target DNA sequences is obtained from the frequency shifts, which are big enough in this work due to an effective biological treatment. The experimental results show that the biosensor has a high sensitivity of 1.2 pg/ml/Hz and high selectivity characteristic is also verified by the few responses of other substances. In combination with wireless transceiver, we develop a wireless receiving and processing system that can directly display the detection results.

  6. Direction-sensitive dark matter search results in a surface laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Miuchi, Kentaro [Cosmic-Ray Group, Department of Physics, Graduate School of Science, Kyoto University Kitashirakawa-oiwakecho, Sakyo-ku, Kyoto 606-8502 (Japan)], E-mail: miuchi@cr.scphys.kyoto-u.ac.jp; Hattori, Kaori; Kabuki, Shigeto; Kubo, Hidetoshi; Kurosawa, Shunsuke; Nishimura, Hironobu; Okada, Yoko; Takada, Atsushi; Tanimori, Toru; Tsuchiya, Ken' ichi; Ueno, Kazuki [Cosmic-Ray Group, Department of Physics, Graduate School of Science, Kyoto University Kitashirakawa-oiwakecho, Sakyo-ku, Kyoto 606-8502 (Japan); Sekiya, Hiroyuki; Takeda, Atsushi [Kamioka Observatory, ICRR, University of Tokyo Higashi-Mozumi, Kamioka cho, Hida 506-1205 (Japan)

    2007-10-11

    We developed a three-dimensional gaseous tracking device and performed a direction-sensitive dark matter search in a surface laboratory. By using 150 Torr carbon-tetrafluoride (CF{sub 4}) gas, we obtained a sky map drawn with the recoil directions of the carbon and fluorine nuclei, and set the first limit on the spin-dependent WIMP (Weakly Interacting Massive Particles)-proton cross section by a direction-sensitive method. Thus, we showed that a WIMP-search experiment with a gaseous tracking device can actually set limits. Furthermore, we demonstrated that this method will potentially play a certain role in revealing the nature of dark matter when a low-background large-volume detector is developed.

  7. Potential evaporation estimation through an unstressed surface energy balance and its sensitivity to climate change

    Science.gov (United States)

    Barella-Ortiz, A.; Polcher, J.; Tuzet, A.; Laval, K.

    2013-06-01

    Potential evaporation (ETP) is a basic input for hydrological and agronomic models, as well as a key variable in most actual evaporation estimations. It has been approached through several diffusive and energy balance methods, out of which the Penman-Monteith equation is recommended as the standard one. In order to deal with the diffusive approach, ETP must be estimated at a sub-diurnal frequency, as currently done in land surface models (LSM). This study presents an improved method, developed in the ORCHIDEE LSM, which consists in estimating ETP through an unstressed surface energy balance (USEB method). The results confirm the quality of the estimation which is currently implemented in the model (Milly, 1992). ETP has also been estimated using a reference equation (computed at a daily time step) provided by the Food and Agriculture Organization (FAO). First, a comparison for a reference period under current climate conditions, shows that both formulations differ, specially in arid areas. However, they supply similar values when FAO's assumption of neutral stability conditions is relaxed, by replacing FAO's aerodynamic resistance by the model's one. Furthermore, if the vapour pressure deficit (VPD) estimated for FAO's equation, is substituted by ORCHIDEE's VPD or its humidity gradient, the daily mean estimate is further improved. In a second step, ETP's sensitivity to climate change is assessed comparing trends in both formulations for the 21st Century. It is found that the USEB method shows a higher sensitivity. Both VPD and the model's humidity gradient, as well as the aerodynamic resistance have been identified as key parameters in governing ETP trends. Finally, the sensitivity study is extended to three empirical approximations based on temperature, net radiation and mass transfer (Hargreaves, Priestley-Taylor and Rohwer, respectively). The sensitivity of these methods is compared to the USEB method's one to test if simplified equations are able to reproduce

  8. Potential evaporation estimation through an unstressed surface energy balance and its sensitivity to climate change

    Directory of Open Access Journals (Sweden)

    A. Barella-Ortiz

    2013-06-01

    Full Text Available Potential evaporation (ETP is a basic input for hydrological and agronomic models, as well as a key variable in most actual evaporation estimations. It has been approached through several diffusive and energy balance methods, out of which the Penman–Monteith equation is recommended as the standard one. In order to deal with the diffusive approach, ETP must be estimated at a sub-diurnal frequency, as currently done in land surface models (LSM. This study presents an improved method, developed in the ORCHIDEE LSM, which consists in estimating ETP through an unstressed surface energy balance (USEB method. The results confirm the quality of the estimation which is currently implemented in the model (Milly, 1992. ETP has also been estimated using a reference equation (computed at a daily time step provided by the Food and Agriculture Organization (FAO. First, a comparison for a reference period under current climate conditions, shows that both formulations differ, specially in arid areas. However, they supply similar values when FAO's assumption of neutral stability conditions is relaxed, by replacing FAO's aerodynamic resistance by the model's one. Furthermore, if the vapour pressure deficit (VPD estimated for FAO's equation, is substituted by ORCHIDEE's VPD or its humidity gradient, the daily mean estimate is further improved. In a second step, ETP's sensitivity to climate change is assessed comparing trends in both formulations for the 21st Century. It is found that the USEB method shows a higher sensitivity. Both VPD and the model's humidity gradient, as well as the aerodynamic resistance have been identified as key parameters in governing ETP trends. Finally, the sensitivity study is extended to three empirical approximations based on temperature, net radiation and mass transfer (Hargreaves, Priestley–Taylor and Rohwer, respectively. The sensitivity of these methods is compared to the USEB method's one to test if simplified equations are

  9. Do spike insoles enhance postural stability and plantar-surface cutaneous sensitivity in the elderly?

    Science.gov (United States)

    Palluel, Estelle; Nougier, Vincent; Olivier, Isabelle

    2008-03-01

    Balance problems are often related to a loss of plantar-sensitivity in elderly people. The purpose of this study was to explore the contribution of plantar cutaneous inputs induced by a spike support surface to the control of stance. Nineteen elderly (mean age 69.0 years, range 62-80) and 19 young adults (mean age 25.9 years, range 21-32) were instructed to stand (standing session) or to walk (walking session) for 5 min with sandals equipped with spike insoles (spike condition). Both sessions also involved a no spike condition in which participants stood or walked for 5 min without these insoles (no spike condition). In all conditions, postural responses were assessed during unperturbed stance and were performed (1) immediately after putting the spike or the no spike insoles, and (2) 5 min after standing or walking with them. Sway parameters, such as centre of foot pressure mean location, surface area, mean speed, root mean square and median frequency on the antero-posterior and medio-lateral axes, were calculated. As postural performances are often related to plantar-surface sensitivity, cutaneous sensitivity threshold was also evaluated with Semmes-Weinstein monofilaments. Although no immediate effect of the spike insoles was found, results indicated that standing or walking for 5 min with sandals equipped with spike insoles led to a significant improvement of quiet standing in the elderly. Balance improvement was also observed in young adults. The results provided evidence that wearing sandals with spike insoles can contribute, at least temporarily, to the improvement of unperturbed stance in elderly people with relatively intact plantar cutaneous sensation. Further research is needed to assess the effects of longer and discontinuous stimulations with spike insoles on postural control.

  10. Relative analytical sensitivity of donor nucleic acid amplification technology screening and diagnostic real-time polymerase chain reaction assays for detection of Zika virus RNA.

    Science.gov (United States)

    Stone, Mars; Lanteri, Marion C; Bakkour, Sonia; Deng, Xutao; Galel, Susan A; Linnen, Jeffrey M; Muñoz-Jordán, Jorge L; Lanciotti, Robert S; Rios, Maria; Gallian, Pierre; Musso, Didier; Levi, José E; Sabino, Ester C; Coffey, Lark L; Busch, Michael P

    2017-03-01

    Zika virus (ZIKV) has spread rapidly in the Pacific and throughout the Americas and is associated with severe congenital and adult neurologic outcomes. Nucleic acid amplification technology (NAT) assays were developed for diagnostic applications and for blood donor screening on high-throughput NAT systems. We distributed blinded panels to compare the analytical performance of blood screening relative to diagnostic NAT assays. A 25-member, coded panel (11 half-log dilutions of a 2013 French Polynesia ZIKV isolate and 2015 Brazilian donor plasma implicated in transfusion transmission, and 3 negative controls) was sent to 11 laboratories that performed 17 assays with 2 to 12 replicates per panel member. Results were analyzed for the percentage reactivity at each dilution and by probit analysis to estimate the 50% and 95% limits of detection (LOD50 and LOD95 , respectively). Donor-screening NAT assays that process approximately 500 µL of plasma into amplification reactions were comparable in sensitivity (LOD50 and LOD95 , 2.5 and 15-18 copies/mL) and were approximately 10-fold to 100-fold more sensitive than research laboratory-developed and diagnostic reverse transcriptase-polymerase chain reaction tests that process from 10 to 30 µL of plasma per amplification. Increasing sample input volume assayed with the Centers for Disease Control and Prevention reverse transcriptase-polymerase chain reaction assays increased the LODs by 10-fold to 30-fold. Blood donor-screening ZIKV NAT assays demonstrate similar excellent sensitivities to assays currently used for screening for transfusion-transmitted viruses and are substantially more sensitive than most other laboratory-developed and diagnostic ZIKV reverse transcriptase-polymerase chain reaction assays. Enhancing sensitivities of laboratory-developed and diagnostic assays may be achievable by increasing sample input. © 2017 AABB.

  11. Increasing the Analytical Sensitivity by Oligonucleotides Modified with Para- and Ortho-Twisted Intercalating Nucleic Acids - TINA

    DEFF Research Database (Denmark)

    Schneider, Uffe V; Géci, Imrich; Jøhnk, Nina

    2011-01-01

    The sensitivity and specificity of clinical diagnostic assays using DNA hybridization techniques are limited by the dissociation of double-stranded DNA (dsDNA) antiparallel duplex helices. This situation can be improved by addition of DNA stabilizing molecules such as nucleic acid intercalators....... Here, we report the synthesis of a novel ortho-Twisted Intercalating Nucleic Acid (TINA) amidite utilizing the phosphoramidite approach, and examine the stabilizing effect of ortho- and para-TINA molecules in antiparallel DNA duplex formation. In a thermal stability assay, ortho- and para......-TINA molecules increased the melting point (Tm) of Watson-Crick based antiparallel DNA duplexes. The increase in Tm was greatest when the intercalators were placed at the 5' and 3' termini (preferable) or, if placed internally, for each half or whole helix turn. Terminally positioned TINA molecules improved...

  12. A less sensitive detector does not necessarily result in a less sensitive method: fast quantification of 13 antiretroviral analytes in plasma with liquid chromatography coupled with tandem mass spectrometry.

    Science.gov (United States)

    Ter Heine, Rob; Rosing, Hilde; Beijnen, Jos H; Huitema, Alwin D R

    2010-08-01

    We previously developed a method for the simultaneous determination of the human immunodeficiency protease inhibitors: amprenavir, atazanavir, darunavir, indinavir, lopinavir, nelfinavir, ritonavir, saquinavir and tipranavir, the active nelfinavir metabolite M8 the non-nucleoside reverse transcriptase inhibitors efavirenz, nevirapine and etravirine and the internal standards dibenzepine, (13)C(6)-efavirenz, D5-saquinavir and D6-indinavir in plasma using liquid chromatography coupled with tandem mass spectrometry with a Sciex API3000 triple quadrupole mass spectrometer and an analytical run time of only 10 min. We report the transfer of this method from the API3000 to a supposedly less sensitive Sciex API365 mass spectrometer. We describe the steps that were undertaken to optimize the sensitivity and validation of the method that we transferred. We showed that transfer of a method to a putative less sensitive detector did not necessarily result in a less sensitive assay, and this method can be applied in laboratories where older mass spectrometers are available. Ultimately, the performance of the method was validated. Accuracy and precision was within 87%-110% and <13%, respectively. No notable loss in selectivity was observed.

  13. A Surface Plasmon Resonance-Based Immunosensors for Sensitive Detection of Heroin

    Science.gov (United States)

    Wu, Zhong-cheng; Chen, Wen-ge; Wang, Lian-chao; Ge, Yu; Yu, Cheng-duan; Fang, Ting-jian

    2000-12-01

    A simple technique for sensitive detection of heroin based on surface-plasmon-resonance has been theoretically and experimentally investigated. The experiment was realized by using an anti-MO monoclonal antibody and a morphine (MO)-bovine serum albumin (MO-BSA) conjugate (antigen). The reason for using MO-BSA in the detection of heroine was also discussed. MO-BSA was immobilized on a gold thin film of SPR sensor chip by physical adsorption. The configuration of the device is allowed to be further miniaturized, which is required for the construction of a portable SPR device in the application of in-situ analysis.

  14. Enhancement of dynamic sensitivity of multiple surface-plasmonic-polaritonic sensor using silver nanoparticles

    CERN Document Server

    Abbas, Farhat; Swiontek, Stephen E; Lakhtakia, Akhlesh

    2015-01-01

    Multiple surface plasmon-polariton (SPP) waves excited at the interface of a homogeneous isotropic metal and a chiral sculptured thin film (STF) impregnated with silver nanoparticles were theoretically assessed for the multiple-SPP-waves-based sensing of a fluid uniformly infiltrating the chiral STF. The Bruggemann homogenization formalism was used in two different modalities to determine the three principal relative permittivity scalars of the silver-nanoparticle-impregnated chiral STF infiltrated uniformly by the fluid. The dynamic sensitivity increased when silver nanoparticles were present, provided their volume fraction did not exceed about 1%.

  15. Measurement of unsteady surface pressure on rotor blades of fans by pressure-sensitive paint

    Science.gov (United States)

    Yokoyama, Hiroshi; Miura, Kouhei; Iida, Akiyoshi

    2017-01-01

    To clarify the unsteady pressure distributions on the rotor blades of an axial fan, a pressure-sensitive paint (PSP) technique was used. To capture the image of the rotating fan as a static image, an optical derotator method with a dove prism was adopted. It was confirmed by preliminary experiments with a resonator and a speaker that the pressure fluctuations with 347 Hz can be measured by the present PSP. The measured mean pressure distributions were compared with the predicted results based on large-eddy simulations. The measured instantaneous surface pressure is instrumental to identify acoustic source of fan noise in the design stage.

  16. Dynamic surface pressure measurements on a square cylinder with pressure sensitive paint

    Energy Technology Data Exchange (ETDEWEB)

    McGraw, C.M.; Khalil, G.; Callis, J.B. [University of Washington, Department of Chemistry, Seattle, WA (United States); Bell, J.H. [Ames Research Center, National Aeronautics and Space Administration, Moffett Field, CA (United States)

    2006-02-01

    The dynamic and static surface pressure on a square cylinder during vortex shedding was measured with pressure sensitive paints (PSPs) at three angles of incidence and a Reynolds number of 8.9 x 10{sup 4}. Oscillations in the phosphorescence intensity of the PSP that occurred at the vortex shedding frequency were observed. From these phosphorescent oscillations, the time-dependent changes in pressure distribution were calculated. This work extends PSP's useful range to dynamic systems where oscillating pressure changes are on the order of 230 Pa and occur at frequencies in the range of 95-125 Hz. (orig.)

  17. Improving the sensitivity limit of surface plasmon resonance biosensors by detecting mixed interference signals

    Science.gov (United States)

    Yuan, W.; Ho, H. P.; Suen, Y. K.; Kong, S. K.; Lin, Chinlon

    2007-11-01

    We demonstrate that the sensitivity limit of intensity-based surface plasmon resonance (SPR) biosensors can be enhanced when we combine the effects of the phase and amplitude contributions instead of detecting the amplitude variation only. Experimental results indicate that an enhancement factor of as much as 20 times is achievable, yet with no compromise in measurement dynamic range. While existing SPR biosensor systems are predominantly based on the angular scheme, which relies on detecting intensity variations associated with amplitude changes only, the proposed scheme may serve as a direct system upgrade approach for these systems. The new measurement scheme may therefore lead to a strong impact in the design of SPR biosensors.

  18. A new multi-domain method based on an analytical control surface for linear and second-order mean drift wave loads on floating bodies

    Science.gov (United States)

    Liang, Hui; Chen, Xiaobo

    2017-10-01

    A novel multi-domain method based on an analytical control surface is proposed by combining the use of free-surface Green function and Rankine source function. A cylindrical control surface is introduced to subdivide the fluid domain into external and internal domains. Unlike the traditional domain decomposition strategy or multi-block method, the control surface here is not panelized, on which the velocity potential and normal velocity components are analytically expressed as a series of base functions composed of Laguerre function in vertical coordinate and Fourier series in the circumference. Free-surface Green function is applied in the external domain, and the boundary integral equation is constructed on the control surface in the sense of Galerkin collocation via integrating test functions orthogonal to base functions over the control surface. The external solution gives rise to the so-called Dirichlet-to-Neumann [DN2] and Neumann-to-Dirichlet [ND2] relations on the control surface. Irregular frequencies, which are only dependent on the radius of the control surface, are present in the external solution, and they are removed by extending the boundary integral equation to the interior free surface (circular disc) on which the null normal derivative of potential is imposed, and the dipole distribution is expressed as Fourier-Bessel expansion on the disc. In the internal domain, where the Rankine source function is adopted, new boundary integral equations are formulated. The point collocation is imposed over the body surface and free surface, while the collocation of the Galerkin type is applied on the control surface. The present method is valid in the computation of both linear and second-order mean drift wave loads. Furthermore, the second-order mean drift force based on the middle-field formulation can be calculated analytically by using the coefficients of the Fourier-Laguerre expansion.

  19. Sensitivity analysis and numerical experiments on transient test of compact heat exchanger surfaces

    Institute of Scientific and Technical Information of China (English)

    Hesheng REN; Lingjun LAI; Yongzheng CUI

    2008-01-01

    A single-blow transient testing technique con-sidering the effect of longitudinal heat conduction is sug-gested for determining the average convection heat transfer coefficient of compact heat exchanger surface. By matching the measured outlet fluid temperature vari-ation with similar theoretical curves, the dimensionless longitudinal conduction parameter λ1, the time constant of the inlet fluid temperature τ+, and the number of heat transfer units Ntu can be determined simultaneously using the Levenberg-Marquardt nonlinear parameter estima-tion method. Both sensitivity analysis and numerical experiments with simulated measurements containing random errors show that the method in the present invest-igation provides satisfactory accuracy of the estimated parameter Ntu, which characterizes the heat transfer per-formance of compact heat exchanger surfaces.

  20. Surface-selective laser sintering of thermolabile polymer particles using water as heating sensitizer

    Energy Technology Data Exchange (ETDEWEB)

    Antonov, E N; Krotova, L I; Minaev, N V; Minaeva, S A; Mironov, A V; Popov, V K [Institute on Laser and Information Technologies of the Russian Academy of Sciencies, Troitsk, Moscow (Russian Federation); Bagratashvili, V N [Department of Chemistry, M.V. Lomonosov Moscow State University, Moscow (Russian Federation)

    2015-11-30

    We report the implementation of a novel scheme for surface-selective laser sintering (SSLS) of polymer particles, based on using water as a sensitizer of laser heating and sintering of particles as well as laser radiation at a wavelength of 1.94 μm, corresponding to the strong absorption band of water. A method of sintering powders of poly(lactide-co-glycolide), a hydrophobic bioresorbable polymer, after modifying its surface with an aqueous solution of hyaluronic acid is developed. The sintering thresholds for wetted polymer are by 3 – 4 times lower than those for sintering in air. The presence of water restricts the temperature of the heated polymer, preventing its thermal destruction. Polymer matrices with a developed porous structure are obtained. The proposed SSLS method can be applied to produce bioresorbable polymer matrices for tissue engineering. (interaction of laser radiation with matter. laser plasma)

  1. Improved Performance of Dye-Sensitized Solar Cells Using a Diethyldithiocarbamate-Modified Surface

    Directory of Open Access Journals (Sweden)

    D. M. B. P. Ariyasinghe

    2013-01-01

    Full Text Available The surface modification of a TiO2 electrode with diethyldithiocarbamate (DEDTC in dye-sensitized solar cells (DSSCs was studied. Results from X-ray photoelectron spectroscopy (XPS indicate that over half of the sulfur atoms become positively charged after the DEDTC treatment of the TiO2 surface. DSSCs were fabricated with TiO2 electrodes modified by adsorbing DEDTC using a simple dip-coating process. The conversion efficiency of the DSSCs has been optimized to 6.6% through the enhancement of the short-circuit current density ( mA/cm2. This is substantially higher compared to the efficiency of 5.9% ( mA/cm2 for the DSSCs made with untreated TiO2 electrodes.

  2. Experimental evidence for extreme surface sensitivity in Auger-Photoelectron Coincidence Spectroscopy (APECS) from solids

    Energy Technology Data Exchange (ETDEWEB)

    Liscio, A.; Gotter, R.; Ruocco, A.; Iacobucci, S.; Danese, A.G.; Bartynski, R.A.; Stefani, G

    2004-07-01

    Core hole creation and subsequent Auger decay processes are studied with unprecedented discrimination by Auger-Photoelectron Coincidence Spectroscopy (APECS). Early works in this field have already pointed out the intrinsic surface sensitivity of these experiments. However, it was not until recently that a model calculation was developed to quantitatively evaluate it. Here we present the first attempt to experimentally establish an effective target thickness for such experiments. The angular distribution of 3p{sub 3/2} photoelectron with kinetic energy of 160 eV is measured in coincidence with the M{sub 3}VV Auger electron with kinetic energy of 55 eV on a Cu (1 1 1) surface. Coincidence and non-coincidence photoelectron angular distributions display differences that, to large extent, are explained by confining the source of the coincident signal within the first two layers of Cu target, thus establishing an experimental upper limit for the effective target thickness of the APECS experiment.

  3. On the extension of the sensitive area of an extensive air shower surface array

    CERN Document Server

    Kh, H Hedayati

    2016-01-01

    A large distance between true and reconstructed core locations of an extensive air shower (EAS) may results in great systematic mis-estimation of EAS parameters. The reconstruction of those EASs whose core locations are outside the boundary of a surface array (outside EAS (OEAS)) results in a large distance of the reconstructed core location from the true one, especially when the true core is far outside the array. Although it may not be mentioned, the identification of OEASs is a necessary and important step in the reconstruction procedure of an EAS. In this paper, an existing technique is optimized for the identification of OEASs. The simultaneous use of this technique and a recently developed approach for reconstructing the core location of an EAS can significantly increase the sensitive area of a surface array.

  4. Redox environment effect on redox sensitive elements in surface sediments of the Changjiang Estuary hypoxia zone

    Institute of Scientific and Technical Information of China (English)

    Shumei XU; Shikui ZHAI; Aibin ZHANG; Huaijing ZHANG; Haijian LU

    2008-01-01

    The grain size and element (including redox sensitive elements and terrigenous elements) concentration of surface sediments from the Changjiang Estuary hypoxia zone and its adjacent sea area were measured in this research.Based on the obtained data,the hypoxic environment's influence on the distribution of elements in surface sediments was further studied.We believe that the "redox environment effect" greatly influences the distribution of the RSE,which reveals the "patchy enrichment pattern" offshore in the hypoxia zone,while the distribution of the terrigenous elements which shows the "stripped enrichment pattern" near shore is mainly affected by "granularity effects".Due to the existence of the hypoxia zone of the Changjiang Estuary,the distribution of the RSE such as Mo,Cd and V in the study area exhibits the characteristics of "redox environment effects".

  5. Assessing modeled Greenland surface mass balance in the GISS Model E2 and its sensitivity to surface albedo

    Science.gov (United States)

    Alexander, Patrick; LeGrande, Allegra N.; Koenig, Lora S.; Tedesco, Marco; Moustafa, Samiah E.; Ivanoff, Alvaro; Fischer, Robert P.; Fettweis, Xavier

    2016-04-01

    The surface mass balance (SMB) of the Greenland Ice Sheet (GrIS) plays an important role in global sea level change. Regional Climate Models (RCMs) such as the Modèle Atmosphérique Régionale (MAR) have been employed at high spatial resolution with relatively complex physics to simulate ice sheet SMB. Global climate models (GCMs) incorporate less sophisticated physical schemes and provide outputs at a lower spatial resolution, but have the advantage of modeling the interaction between different components of the earth's oceans, climate, and land surface at a global scale. Improving the ability of GCMs to represent ice sheet SMB is important for making predictions of future changes in global sea level. With the ultimate goal of improving SMB simulated by the Goddard Institute for Space Studies (GISS) Model E2 GCM, we compare simulated GrIS SMB against the outputs of the MAR model and radar-derived estimates of snow accumulation. In order to reproduce present-day climate variability in the Model E2 simulation, winds are constrained to match the reanalysis datasets used to force MAR at the lateral boundaries. We conduct a preliminary assessment of the sensitivity of the simulated Model E2 SMB to surface albedo, a parameter that is known to strongly influence SMB. Model E2 albedo is set to a fixed value of 0.8 over the entire ice sheet in the initial configuration of the model (control case). We adjust this fixed value in an ensemble of simulations over a range of 0.4 to 0.8 (roughly the range of observed summer GrIS albedo values) to examine the sensitivity of ice-sheet-wide SMB to albedo. We prescribe albedo from the Moderate Resolution Imaging Spectroradiometer (MODIS) MCD43A3 v6 to examine the impact of a more realistic spatial and temporal variations in albedo. An age-dependent snow albedo parameterization is applied, and its impact on SMB relative to observations and the RCM is assessed.

  6. Cisapride a green analytical reagent for rapid and sensitive determination of bromate in drinking water, bread and flour additives by oxidative coupling spectrophotometric methods

    Science.gov (United States)

    Al Okab, Riyad Ahmed

    2013-02-01

    Green analytical methods using Cisapride (CPE) as green analytical reagent was investigated in this work. Rapid, simple, and sensitive spectrophotometric methods for the determination of bromate in water sample, bread and flour additives were developed. The proposed methods based on the oxidative coupling between phenoxazine and Cisapride in the presence of bromate to form red colored product with max at 520 nm. Phenoxazine and Cisapride and its reaction products were found to be environmentally friendly under the optimum experimental condition. The method obeys beers law in concentration range 0.11-4.00 g ml-1 and molar absorptivity 1.41 × 104 L mol-1 cm-1. All variables have been optimized and the presented reaction sequences were applied to the analysis of bromate in water, bread and flour additive samples. The performance of these method was evaluated in terms of Student's t-test and variance ratio F-test to find out the significance of proposed methods over the reference method. The combination of pharmaceutical drugs reagents with low concentration create some unique green chemical analyses.

  7. Analytical protocol for the sensitive determination of mannitol, sorbitol and glucose containing powders in pharmaceutical workplaces by ion chromatography using a pulsed amperometric detector.

    Science.gov (United States)

    Butler, Owen; Forder, James; Saunders, John

    2015-03-15

    Workers in the pharmaceutical industry can potentially be exposed to airborne dusts and powders that can contain potent active pharmaceutical ingredients (API). Occupational hygienists and health and safety professionals need to assess and ultimately minimise such inhalation and dermal exposure risks. Containment of dusts at source is the first line of defence but the performance of such technologies needs to be verified, for which purpose the good practice guide: assessing the particulate containment performance of pharmaceutical equipment, produced by the International Society for Pharmaceutical Engineering (ISPE), is a widely used reference document. This guide recommends the use of surrogate powders that can be used to challenge the performance of such containment systems. Materials such as lactose and mannitol are recommended as their physical properties (adhesion, compactability, dustiness, flow characteristics and particle sizes) mimic those of API-containing materials typically handled. Furthermore they are safe materials to use, are available in high purity and can be procured at a reasonable cost. The aim of this work was to develop and validate a sensitive ion-chromatography based analytical procedure for the determination of surrogate powders collected on filter samples so as to meet analytical requirements set out in this ISPE guide.

  8. Colored grounds of gilt stucco surfaces as analyzed by a combined microscopic, spectroscopic and elemental analytical approach.

    Science.gov (United States)

    Sansonetti, A; Striova, J; Biondelli, D; Castellucci, E M

    2010-08-01

    A survey of gilts applied to stucco surfaces that specifically focuses on the compositions of their colored grounds is reported. Gilt samples of a common geographical (Lombardy in Italy) and temporal provenance (17th-18th century) were studied in the form of polished cross-sections by optical and electron microscopy (SEM-EDS), micro-Raman (microRaman) spectroscopy and Fourier-transform infrared microspectroscopy (microFTIR). Comparing samples with superimposed grounds and gilts enabled light to be shed on the choice of specific materials, their stratigraphic functions, decorative effects, and technological performances. Iron oxide pigments were found in the older grounds, sometimes in the presence of lead white (2PbCO(3).Pb(OH)(2)) or minium (Pb(3)O(4)). In more recent grounds, chrome yellow (PbCrO(4)), chrome orange (PbCrO(4).PbO), cinnabar (alpha-HgS) and barium white (BaSO(4)), invariably mixed with lead white, were encountered. Evidence for the use of organic mordants (colophony and wax, or siccative oil) was obtained by microFTIR. This combined microFTIR and microRaman spectroscopic and elemental (SEM-EDS) analytical approach enhances knowledge of the composition of gold grounds, their variability and their chronological evolution.

  9. Immobilization of β-galactosidase onto functionalized graphene nano-sheets using response surface methodology and its analytical applications.

    Directory of Open Access Journals (Sweden)

    Devesh Kishore

    Full Text Available BACKGROUND: β-Galactosidase is a vital enzyme with diverse application in molecular biology and industries. It was covalently attached onto functionalized graphene nano-sheets for various analytical applications based on lactose reduction. METHODOLOGY/PRINCIPAL FINDINGS: Response surface methodology based on Box-Behnken design of experiment was used for determination of optimal immobilization conditions, which resulted in 84.2% immobilization efficiency. Native and immobilized functionalized graphene was characterized with the help of transmission and scanning electron microscopy, followed by Fourier transform infrared (FTIR spectroscopy. Functionalized graphene sheets decorated with islands of immobilized enzyme were evidently visualized under both transmission and scanning electron microscopy after immobilization. FTIR spectra provided insight on various chemical interactions and bonding, involved during and after immobilization. Optimum temperature and energy of activation (E(a remains unchanged whereas optimum pH and K(m were changed after immobilization. Increased thermal stability of enzyme was observed after conjugating the enzyme with functionalized graphene. SIGNIFICANCE: Immobilized β-galactosidase showed excellent reusability with a retention of more than 92% enzymatic activity after 10 reuses and an ideal performance at broad ranges of industrial environment.

  10. 3-D description of fracture surfaces and stress-sensitivity analysis for naturally fractured reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, S.Q.; Jioa, D.; Meng, Y.F.; Fan, Y.

    1997-08-01

    Three kinds of reservoir cores (limestone, sandstone, and shale with natural fractures) were used to study the effect of morphology of fracture surfaces on stress sensitivity. The cores, obtained from the reservoirs with depths of 2170 to 2300 m, have fractures which are mated on a large scale, but unmated on a fine scale. A specially designed photoelectric scanner with a computer was used to describe the topography of the fracture surfaces. Then, theoretical analysis of the fracture closure was carried out based on the fracture topography generated. The scanning results show that the asperity has almost normal distributions for all three types of samples. For the tested samples, the fracture closure predicted by the elastic-contact theory is different from the laboratory measurements because plastic deformation of the aspirates plays an important role under the testing range of normal stresses. In this work, the traditionally used elastic-contact theory has been modified to better predict the stress sensitivity of reservoir fractures. Analysis shows that the standard deviation of the probability density function of asperity distribution has a great effect on the fracture closure rate.

  11. The clear-sky greenhouse effect sensitivity to a sea surface temperature change

    Science.gov (United States)

    Duvel, J. PH.; Breon, F. M.

    1991-01-01

    The clear-sky greenhouse effect response to a sea surface temperature (SST or Ts) change is studied using outgoing clear-sky longwave radiation measurements from the Earth Radiation Budget Experiment. Considering geographical distributions for July 1987, the relation between the SST, the greenhouse effect (defined as the outgoing infrared flux trapped by atmospheric gases), and the precipitable water vapor content (W), estimated by the Special Sensor Microwave Imager, is analyzed first. A fairly linear relation between W and the normalized greenhouse effect g, is found. On the contrary, the SST dependence of both W and g exhibits nonlinearities with, especially, a large increase for SST above 25 C. This enhanced sensitivity of g and W can be interpreted in part by a corresponding large increase of atmospheric water vapor content related to the transition from subtropical dry regions to equatorial moist regions. Using two years of data (1985 and 1986), the normalized greenhouse effect sensitivity to the sea surface temperature is computed from the interannual variation of monthly mean values.

  12. Voltage-sensitive styryl dyes as singlet oxygen targets on the surface of bilayer lipid membrane.

    Science.gov (United States)

    Sokolov, V S; Gavrilchik, A N; Kulagina, A O; Meshkov, I N; Pohl, P; Gorbunova, Yu G

    2016-08-01

    Photosensitizers are widely used as photodynamic therapeutic agents killing cancer cells by photooxidation of their components. Development of new effective photosensitive molecules requires profound knowledge of possible targets for reactive oxygen species, especially for its singlet form. Here we studied photooxidation of voltage-sensitive styryl dyes (di-4-ANEPPS, di-8-ANEPPS, RH-421 and RH-237) by singlet oxygen on the surface of bilayer lipid membranes commonly used as cell membrane models. Oxidation was induced by irradiation of a photosensitizer (aluminum phthalocyanine tetrasulfonate) and monitored by the change of dipole potential on the surface of the membrane. We studied the drop of the dipole potential both in the case when the dye molecules were adsorbed on the same side of the lipid bilayer as the photosensitizer (cis-configuration) and in the case when they were adsorbed on the opposite side (trans-configuration). Based on a simple model, we determined the rate of oxidation of the dyes from the kinetics of change of the potential during and after irradiation. This rate is proportional to steady-state concentration of singlet oxygen in the membrane under irradiation. Comparison of the oxidation rates of various dyes reveals that compounds of ANEPPS series are more sensitive to singlet oxygen than RH type dyes, indicating that naphthalene group is primarily responsible for their oxidation.

  13. Optimal wavy surface to suppress vortex shedding using second-order sensitivity to shape changes

    CERN Document Server

    Tammisola, Outi

    2016-01-01

    A method to find optimal 2nd-order perturbations is presented, and applied to find the optimal spanwise-wavy surface for suppression of cylinder wake instability. Second-order perturbations are required to capture the stabilizing effect of spanwise waviness, which is ignored by standard adjoint-based sensitivity analyses. Here, previous methods are extended so that (i) 2nd-order sensitivity is formulated for base flow changes satisfying linearised Navier-Stokes, and (ii) the resulting method is applicable to a 2D global instability problem. This makes it possible to formulate 2nd-order sensitivity to shape modifications. Using this formulation, we find the optimal shape to suppress the a cylinder wake instability. The optimal shape is then perturbed by random distributions in full 3D stability analysis to confirm that it is a local optimal at the given amplitude and wavelength. Furthermore, it is shown that none of the 10 random wavy shapes alone stabilize the wake flow at Re=50, while the optimal shape does....

  14. Sensitivity Analysis of Entropy Generation in Nanofluid Flow inside a Channel by Response Surface Methodology

    Directory of Open Access Journals (Sweden)

    Bijan Darbari

    2016-02-01

    Full Text Available Nanofluids can afford excellent thermal performance and have a major role in energy conservation aspect. In this paper, a sensitivity analysis has been performed by using response surface methodology to calculate the effects of nanoparticles on the entropy generation. For this purpose, the laminar forced convection of Al2O3-water nanofluid flow inside a channel is considered. The total entropy generation rates consist of the entropy generation rates due to heat transfer and friction loss are calculated by using velocity and temperature gradients. The continuity, momentum and energy equations have been solved numerically using a finite volume method. The sensitivity of the entropy generation rate to different parameters such as the solid volume fraction, the particle diameter, and the Reynolds number is studied in detail. Series of simulations were performed for a range of solid volume fraction 0 ≤ ϕ ≤ 0.05 , particle diameter 30  nm ≤ d p ≤ 90 ​ nm , and the Reynolds number 200 ≤ Re ≤ 800. The results showed that the total entropy generation is more sensitive to the Reynolds number rather than the nanoparticles diameter or solid volume fraction. Also, the magnitude of total entropy generation, which increases with increase in the Reynolds number, is much higher for the pure fluid rather than the nanofluid.

  15. Potential Evaporation Computation through an Unstressed Surface Energy Balance and its Sensitivity to Climate Change Effect

    Science.gov (United States)

    Barella-Ortiz, Anaïs; Polcher, Jan; Tuzet, Andrée; Laval, Katia

    2013-04-01

    Potential evaporation (ETP) is a basic input for hydrological and agronomic models, as well as a key variable in most actual evaporation estimations. It has been approached through several diffusive and energy balance methods, out of which the Penman-Monteith equation is recommended as the standard one. In order to deal with the diffusive approach, ETP must be estimated at a sub-diurnal frequency, as currently done in land surface models (LSM). This study presents an improved method, developed in the ORCHIDEE LSM, which consists in estimating ETP through an unstressed surface energy balance (USEB method). The values provided confirm the quality of the estimation which is currently implemented (Milly, 1992). ETP has also been estimated using a reference equation (computed at a daily time step) provided by the Food and Agriculture Organization (FAO). In the first place, a comparison for a reference period of 11 years shows that both formulations differ, specially in arid areas. However, they supply similar values when FAO's assumption of neutral stability conditions is relaxed, by replacing FAO's aerodynamic resistance by the model's one. Additionally, if the vapour pressure deficit (VPD) is also substituted by either ORCHIDEE's VPD or its humidity gradient, the daily mean estimate is further improved. ETP's sensitivity to climate change is assessed comparing trends in both formulations for the 21st Century. It is found that the USEB method shows a higher sensitivity mainly due to FAO's assumption of neutral stability conditions and to a lesser extent, to the approximation proposed for the VPD. Both FAO's VPD and the model's humidity gradient, as well as ORCHIDEE's aerodynamic resistance have been identified as key parameters in governing ETP trends. Finally, the sensitivity study is extended to 3 empirical approximations based on temperature, net radiation and mass transfer (Hargreaves, Priestley - Taylor and Rohwer, respectively). When compared to the USEB method

  16. Enhanced sensitivity of localized surface plasmon resonance biosensor by phase interrogation

    Science.gov (United States)

    Li, Chung-Tien; Chen, How-foo; Yen, Ta-Jen

    2011-05-01

    We proposed an innovative phase interrogation method for localized surface plasmon resonance (LSPR) detection. To our knowledge, this is the first demonstration of LSPR biosensor by phase interrogation. LSPR is realized as the plasmonic resonance within confined metal nanoparticle. Nanoparticle couples the light by means of a non-radiative inter-band absorption, and a scattering from surface plasmon oscillation, the total contribution is the optical extinction of nanoparticles. Due to the variety of resonance types, LSPR is extensively studied in the field of biological sensing, imaging, and medical therapeutics. Generally, LSPR is probed by optical intensity variation of continuous wavelength, in other words, wavelength interrogation. LSPR sensitivity probed by this method is ranged from several tens nm/RIU to less than 1000nm/RIU depending on the nanostructure and metal species, which at least an order of magnitude less than conventional SPR biosensor in wavelength interrogation. In this work, an innovative common-path phase interrogation system is applied for LSPR detection. Phase difference in our home-made system is simply extracted through the correlation of optical intensity under different polarization without any heterodyne optical modulator or piezoelectric transducer, and thus low down the cost and complexity in optical setup. In addition, signal-to-noise ratio is substantially reduced since the signal wave and reference wave share the common path. In our preliminary results, LSPR resolution of Au nanodisk array is 1.74 x 10-4 RIU by wavelength interrogation; on the other side, LSPR resolution of Au nanodisk array is 2.02x10-6 RIU in phase interrogation. LSPR sensitivity is around one order of magnitude enhanced. In conclusion, we demonstrated that LSPR sensitivity can be further enhanced by phase interrogation.

  17. Surface Potential and Threshold Voltage Model of Fully Depleted Narrow Channel SOI MOSFET Using Analytical Solution of 3D Poisson’s Equation

    Directory of Open Access Journals (Sweden)

    Prashant Mani

    2015-06-01

    Full Text Available The present paper is about the modeling of surface potential and threshold voltage of Fully Depleted Silicon on Insulator MOSFET. The surface potential is calculated by solving the 3D Poisson’s equation analytically. The appropriate boundary conditions are used in calculations. The effect of narrow channel width and short channel length for suppression of SCE is analyzed. The narrow channel width effect in the threshold voltage is analyzed for thin film Fully Depleted SOI MOSFET.

  18. Preanalytical and analytical variation of surface-enhanced laser desorption-ionization time-of-flight mass spectrometry of human serum

    DEFF Research Database (Denmark)

    Albrethsen, Jakob; Bøgebo, Rikke; Olsen, Jesper

    2006-01-01

    BACKGROUND: Surface-enhanced laser desorption-ionization time-of-flight (SELDI-TOF) mass spectrometry of human serum is a potential diagnostic tool in human diseases. In the present study, the preanalytical and analytical variation of SELDI-TOF mass spectrometry of serum was assessed in healthy...

  19. Modern Analytical Methods Applied to Earth and Planetary Sciences for Micro, Nano and Pico Space Devices and Robots in Landing Site Selection and Surface Investigation

    Science.gov (United States)

    Vizi, P. G.; Bérczi, Sz.; Horváth, I.; Horváth, A. F.; Vizi, J. Cs.

    2014-11-01

    Fleet of Nano and Pico Sized Space Devices and Robots (NPSDR) are deployable to realize and accomplish in situ modern analytical methods in wide range of Earth and planetary sciences. Shorter time and bigger field of surfaces and volumes of space.

  20. Proteolysis on the body surface of pyrethroid-sensitive and resistant Varroa destructor.

    Science.gov (United States)

    Strachecka, Aneta; Borsuk, Grzegorz; Olszewski, Krzysztof; Paleolog, Jerzy; Lipiński, Zbigniew

    2013-03-01

    The aim of this work was to determine the activity of proteases and protease inhibitors sampled from the body surface of tau-fluvalinate-sensitive and resistant V. destructor. Proteins were isolated from the tau-fluvalinate-sensitive and resistant mites, while mites untreated with tau-fluvalinate constituted the control. Subsequently, the following methodology was applied: protein concentration assay by the Lowry method - as modified by Schacterle and Pollack; assay of proteolytic activity in relation to various substrates (gelatine, haemoglobin, ovoalbumin, albumin, cytochrome C, casein) by the modified Anson method; identification of proteolytic activity in relation to diagnostic inhibitors of proteolytic enzymes (pepstatin A, PMSF, iodoacetamide, o-phenantrolin), using the Lee and Lin method; identification of acidic, neutral and basic protease activities by means of the modified Anson method; electrophoretic analysis of proteins in a polyacrylamide gel for protease detection with the Laemmli method and for protease inhibitor detection with the Felicioli method. The highest value of protein concentration was found in the tau-fluvalinate-sensitive V. destructor, while the highest activity levels of acidic, neutral and alkaline proteases were observed in the tau-fluvalinate-resistant mites. Aspartic, serine, thiolic and metallic proteases were found in the drug-resistant and drug-sensitive Varroa mites. The control samples were found to contain aspartic and serine proteases. In an acidic and alkaline environment, the results revealed a complete loss of inhibitor activities in the in vitro analyses and electrophoresis. Serine protease inhibitor activities (at pH 7.0) were high, especially in the group of tau-fluvalinate-resistant mites.

  1. A Monte Carlo/response surface strategy for sensitivity analysis: application to a dynamic model of vegetative plant growth

    Science.gov (United States)

    Lim, J. T.; Gold, H. J.; Wilkerson, G. G.; Raper, C. D. Jr; Raper CD, J. r. (Principal Investigator)

    1989-01-01

    We describe the application of a strategy for conducting a sensitivity analysis for a complex dynamic model. The procedure involves preliminary screening of parameter sensitivities by numerical estimation of linear sensitivity coefficients, followed by generation of a response surface based on Monte Carlo simulation. Application is to a physiological model of the vegetative growth of soybean plants. The analysis provides insights as to the relative importance of certain physiological processes in controlling plant growth. Advantages and disadvantages of the strategy are discussed.

  2. Benchmarking sensitivity of biophysical processes to leaf area changes in land surface models

    Science.gov (United States)

    Forzieri, Giovanni; Duveiller, Gregory; Georgievski, Goran; Li, Wei; Robestson, Eddy; Kautz, Markus; Lawrence, Peter; Ciais, Philippe; Pongratz, Julia; Sitch, Stephen; Wiltshire, Andy; Arneth, Almut; Cescatti, Alessandro

    2017-04-01

    Land surface models (LSM) are widely applied as supporting tools for policy-relevant assessment of climate change and its impact on terrestrial ecosystems, yet knowledge of their performance skills in representing the sensitivity of biophysical processes to changes in vegetation density is still limited. This is particularly relevant in light of the substantial impacts on regional climate associated with the changes in leaf area index (LAI) following the observed global greening. Benchmarking LSMs on the sensitivity of the simulated processes to vegetation density is essential to reduce their uncertainty and improve the representation of these effects. Here we present a novel benchmark system to assess model capacity in reproducing land surface-atmosphere energy exchanges modulated by vegetation density. Through a collaborative effort of different modeling groups, a consistent set of land surface energy fluxes and LAI dynamics has been generated from multiple LSMs, including JSBACH, JULES, ORCHIDEE, CLM4.5 and LPJ-GUESS. Relationships of interannual variations of modeled surface fluxes to LAI changes have been analyzed at global scale across different climatological gradients and compared with satellite-based products. A set of scoring metrics has been used to assess the overall model performances and a detailed analysis in the climate space has been provided to diagnose possible model errors associated to background conditions. Results have enabled us to identify model-specific strengths and deficiencies. An overall best performing model does not emerge from the analyses. However, the comparison with other models that work better under certain metrics and conditions indicates that improvements are expected to be potentially achievable. A general amplification of the biophysical processes mediated by vegetation is found across the different land surface schemes. Grasslands are characterized by an underestimated year-to-year variability of LAI in cold climates

  3. Antimicrobial activity of different copper alloy surfaces against copper resistant and sensitive Salmonella enterica.

    Science.gov (United States)

    Zhu, Libin; Elguindi, Jutta; Rensing, Christopher; Ravishankar, Sadhana

    2012-05-01

    Copper has shown antibacterial effects against foodborne pathogens. The objective of this study was to evaluate the antibacterial activity of copper surfaces on copper resistant and sensitive strains of Salmonella enterica. Six different copper alloy coupons (60-99.9% copper) were tested along with stainless steel as the control. The coupons were surface inoculated with either S. Enteritidis or one of the 3 copper resistant strains, S. Typhimurium S9, S19 and S20; stored under various incubation conditions at room temperature; and sampled at various times up to 2 h. The results showed that under dry incubation conditions, Salmonella only survived 10-15 min on high copper content alloys. Salmonella on low copper content alloys showed 3-4 log reductions. Under moist incubation conditions, no survivors were detected after 30 min-2 h on high copper content alloys, while the cell counts decreased 2-4 logs on low copper content coupons. Although the copper resistant strains survived better than S. Enteritidis, they were either completely inactivated or survival was decreased. Copper coupons showed better antimicrobial efficacy in the absence of organic compounds. These results clearly show the antibacterial effects of copper and its potential as an alternative to stainless steel for selected food contact surfaces.

  4. Highly sensitive and reproducible silicon-based surface-enhanced Raman scattering sensors for real applications.

    Science.gov (United States)

    Wang, Houyu; Jiang, Xiangxu; He, Yao

    2016-08-15

    During the past few decades, thanks to silicon nanomaterials' outstanding electronic/optical/mechanical properties, large surface-to-volume ratio, abundant surface chemistry, facile tailorability and good compatibility with modern semiconductor industry, different dimensional silicon nanostructures have been widely employed for rationally designing and fabricating high-performance surface-enhanced Raman scattering (SERS) sensors for the detection of various chemical and biological species. Among these, two-dimensional silicon nanostructures made of metal nanoparticle-modified silicon wafers and three-dimensional silicon nanostructures made of metal nanoparticle-decorated SiNW arrays are of particular interest, and have been extensively exploited as promising silicon-based SERS-active substrates for the construction of high-performance SERS sensors. With an aim to retrospect these important and exciting achievements, we herein focus on reviewing recent representative studies on silicon-based SERS sensors for sensing applications from a broad perspective and possible future direction, promoting readers' awareness of these novel powerful silicon-based SERS sensing technologies. Firstly, we summarize the two unique merits of silicon-based SERS sensors, and those are high sensitivity and good reproducibility. Next, we present recent advances of two- and three-dimensional silicon-based SERS sensors, especially for real applications. Finally, we discuss the major challenges and prospects for the development of silicon-based SERS sensors.

  5. Development of a new microparticle-enhanced turbidimetric assay for C-reactive protein with superior features in analytical sensitivity and dynamic range.

    Science.gov (United States)

    Eda, S; Kaufmann, J; Roos, W; Pohl, S

    1998-01-01

    Novel assay techniques were applied to a newly developed microparticle-based assay for C-reactive protein (CRP). By using two different sized microparticles covalently coated with two monoclonal antibodies of different reactivity, high analytical sensitivity and a high upper measuring limit could be simultaneously attained, resulting in a remarkably wide dynamic range. This range was further increased by calculating the signal (reaction rate) optimally with a new software capability of COBAS INTEGRA, a clinical chemistry analyzer. The assay showed high precision between 2 mg/l and 160 mg/l with use of only 2.5 microl specimen. The detection limit was estimated as 0.3 mg/l CRP. The assay was four to eight times more sensitive and precise than existing turbidimetric or nephelometric assays with comparable upper measuring limits. The assay also showed good linearity and correlated well with commercial assays. This new microparticle-based CRP assay provides the accuracy and precision that are required to determine CRP at low concentrations where new clinical implications such as prognosis of cardiovascular diseases are envisaged. The assay's wide dynamic range will additionally lead to a reduction in the number of repeated analyses, thus improving the efficiency of CRP determinations in clinical laboratories.

  6. Sensitive and rapid analytical method for the quantification of glucosamine in human plasma by ultra high performance liquid chromatography with tandem mass spectrometry.

    Science.gov (United States)

    Yang, Wen; Zheng, Xiaohong; Simpemba, Ernest; Ma, Pengcheng; Ding, Li

    2015-06-01

    A highly sensitive and rapid ultra high performance liquid chromatography with tandem mass spectrometry method has been developed and validated for the determination of glucosamine in human plasma using miglitol as the internal standard. Special attention was paid to achieve the high throughput and sensitivity of the established method, and the absence of a matrix effect on the analytes. The sample preparation procedure involved a simple deproteinization step. The chromatographic separation was achieved on a Waters ACQUITY HSS Cyano column using a mixture of acetonitrile/2 mM ammonium acetate solution containing 0.03% formic acid (80:20, v/v) as the mobile phase with a very short run time of 1.5 min. This method was validated over the concentration range of 10-3000 ng/mL for glucosamine. The intra- and inter-batch precision was glucosamine level in human plasma, which has not been reported in detail until now. The method was successfully applied to characterize the pharmacokinetic profile of glucosamine in healthy volunteers following a single oral administration of 750 or 1500 mg glucosamine hydrochloride.

  7. High ethanol sensitivity of palladium/TiO2 nanobelt surface heterostructures dominated by enlarged surface area and nano-Schottky junctions.

    Science.gov (United States)

    Wang, Dongzhou; Zhou, Weijia; Hu, Peiguang; Guan, Yu; Chen, Limei; Li, Jianhua; Wang, Guancong; Liu, Hong; Wang, Jiyang; Cao, Guozhong; Jiang, Huaidong

    2012-12-15

    TiO(2) nanobelts were prepared by the hydrothermal growth method. The surface of the nanobelts was coarsened by selective acid corrosion and functionalized with Pd catalyst particles. Three nanobelt samples (TiO(2) nanobelts, surface-coarsened TiO(2) nanobelts and Pd nanoparticle/TiO(2) nanobelt surface heterostructures) were configured as gas sensors and their sensing ability was measured. Both the surface-coarsened nanobelts and the Pd nanoparticle-decorated TiO(2) nanobelts exhibited dramatically improved sensitivity to ethanol vapor. Pd nanoparticle-decorated TiO(2) nanobelts with surface heterostructures exhibited the best sensitivity, selectivity, working temperature, response/recovery time, and reproducibility. The excellent ethanol sensing performance is attributed to the large surface area and enhancement by Schottky barrier-type junctions between the Pd nanoparticles and TiO(2) nanobelts.

  8. Pulsed laser deposition of Ag nanoparticles on titanium hydroxide/oxide nanobelt arrays for highly sensitive surface-enhanced Raman spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Jing, Yuting; Wang, Huanwen; Zhao, Jie; Yi, Huan; Wang, Xuefeng, E-mail: xfwang@tongji.edu.cn

    2015-08-30

    Highlights: • Silver nanoparticles (NPs) were deposited on Ti(OH){sub 4} nanobelt by pulsed laser deposition (PLD). • The highest enhancement factor of 10{sup 6} and a maximum relative standard deviation (RSD) of 0.18. • Ag{sub 2}O play important role for the high sensitivity Raman phenomenon. • Charge transfer from Ag NPs is also responsible for the enhancement ability. - Abstract: Surface-enhanced Raman scattering (SERS) substrate of Ti(OH){sub 4} nanobelt arrays (NBAs) was synthesized by a hydrothermal reaction, on which silver nanoparticles (NPs) were deposited by pulsed laser deposition (PLD). Field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) revealed the effective high specific surface area with silver NPs decorated on three-dimensional NBAs. Using rhodamine 6G (R6G) as an analyte molecule, the highest enhancement factor of 10{sup 6} and a maximum relative standard deviation (RSD) of 0.18 were obtained. It has been found that the specific morphology of these composite nanobelt arrays and the formation of Ag{sub 2}O play important role for the high sensitivity Raman phenomenon. In addition, the surface plasmon resonance wavelength of Ag decorated Ti(OH){sub 4} NBAs and the charge transfer from Ag NPs are also responsible for the enhancement ability. For comparison SERS was investigated with silver particles decorated on TiO{sub 2} NBAs, which is much less active.

  9. Potential evaporation estimation through an unstressed surface-energy balance and its sensitivity to climate change

    Science.gov (United States)

    Barella-Ortiz, A.; Polcher, J.; Tuzet, A.; Laval, K.

    2013-11-01

    Potential evaporation (ETP) is a basic input for many hydrological and agronomic models, as well as a key variable in most actual evaporation estimations. It has been approached through several diffusive and energy balance methods, out of which the Penman-Monteith equation is recommended as the standard one. In order to deal with the diffusive approach, ETP must be estimated at a sub-diurnal frequency, as currently done in land surface models (LSMs). This study presents an improved method, developed in the ORCHIDEE LSM, which consists of estimating ETP through an unstressed surface-energy balance (USEB method). The results confirm the quality of the estimation which is currently implemented in the model (Milly, 1992). The ETP underlying the reference evaporation proposed by the Food and Agriculture Organization, FAO, (computed at a daily time step) has also been analysed and compared. First, a comparison for a reference period under current climate conditions shows that USEB and FAO's ETP estimations differ, especially in arid areas. However, they produce similar values when the FAO's assumption of neutral stability conditions is relaxed, by replacing FAO's aerodynamic resistance by that of the model's. Furthermore, if the vapour pressure deficit (VPD) estimated for the FAO's equation, is substituted by ORCHIDEE's VPD or its humidity gradient, the agreement between the daily mean estimates of ETP is further improved. In a second step, ETP's sensitivity to climate change is assessed by comparing trends in these formulations for the 21st century. It is found that the USEB method shows a higher sensitivity than the FAO's. Both VPD and the model's humidity gradient, as well as the aerodynamic resistance have been identified as key parameters in governing ETP trends. Finally, the sensitivity study is extended to two empirical approximations based on net radiation and mass transfer (Priestley-Taylor and Rohwer, respectively). The sensitivity of these ETP estimates is

  10. Surface modifications of photoanodes in dye sensitized solar cells: enhanced light harvesting and reduced recombination

    Science.gov (United States)

    Saxena, Vibha; Aswal, D. K.

    2015-06-01

    In a quest to harvest solar power, dye-sensitized solar cells (DSSCs) have potential for low-cost eco-friendly photovoltaic devices. The major processes which govern the efficiency of a DSSC are photoelectron generation, injection of photo-generated electrons to the conduction band (CB) of the mesoporous nanocrystalline semiconductor (nc-SC); transport of CB electrons through nc-SC and subsequent collection of CB electrons at the counter electrode (CE) through the external circuit; and dye regeneration by redox couple or hole transport layer (HTL). Most of these processes occur at various interfaces of the photoanode. In addition, recombination losses of photo-generated electrons with either dye or redox molecules take place at the interfaces. Therefore, one of the key requirements for high efficiency is to improve light harvesting of the photoanode and to reduce the recombination losses at various interfaces. In this direction, surface modification of the photoanode is the simplest method among the various other approaches available in the literature. In this review, we present a comprehensive discussion on surface modification of the photoanode, which has been adopted in the literature for not only enhancing light harvesting but also reducing recombination. Various approaches towards surface modification of the photoanode discussed are (i) fluorine-doped tin oxide (FTO)/nc-SC interface modified via a compact layer of semiconductor material which blocks exposed sites of FTO to electrolyte (or HTL), (ii) nc-SC/dye interface modification either through acid treatment resulting in enhanced dye loading due to a positively charged surface or by depositing insulating/semiconducting blocking layer on the nc-SC surface, which acts as a tunneling barrier for recombination, (iii) nc-SC/dye interface modified by employing co-adsorbents which helps in reducing the dye aggregation and thereby recombination, and (iv) dye/electrolyte (or dye/HTL) interface modification using

  11. Sensitivity of Greenland Ice Sheet surface mass balance to surface albedo parameterization: a study with a regional climate model

    Directory of Open Access Journals (Sweden)

    J. H. van Angelen

    2012-04-01

    Full Text Available We present a sensitivity study of the surface mass balance (SMB of the Greenland Ice Sheet, as modeled using a regional atmospheric climate model, to various parameter settings in the albedo parameterization. The snow albedo parameterization uses grain size as a prognostic variable and further depends on cloud cover, solar zenith angle and black carbon concentration. For the control experiment the overestimation of absorbed shortwave radiation (+6 % at the K-transect (West Greenland for the period 2004–2009 is considerably reduced compared to the previous density-dependent albedo parameterization (+22 %. To simulate realistic snow albedo values, a small concentration of black carbon is needed. A background ice albedo field derived from MODIS imagery improves the agreement between the modeled and observed SMB gradient along the K-transect. The effect of enhanced retention and refreezing is a decrease of the albedo due to an increase in snow grain size. As a secondary effect of refreezing the snowpack is heated, enhancing melt and further lowering the albedo. Especially in a warmer climate this process is important, since it reduces the refreezing potential of the firn layer covering the Greenland Ice Sheet.

  12. Sensitivity of Greenland Ice Sheet surface mass balance to surface albedo parameterization: a study with a regional climate model

    Directory of Open Access Journals (Sweden)

    J. H. van Angelen

    2012-10-01

    Full Text Available We present a sensitivity study of the surface mass balance (SMB of the Greenland Ice Sheet, as modeled using a regional atmospheric climate model, to various parameter settings in the albedo scheme. The snow albedo scheme uses grain size as a prognostic variable and further depends on cloud cover, solar zenith angle and black carbon concentration. For the control experiment the overestimation of absorbed shortwave radiation (+6% at the K-transect (west Greenland for the period 2004–2009 is considerably reduced compared to the previous density-dependent albedo scheme (+22%. To simulate realistic snow albedo values, a small concentration of black carbon is needed, which has strongest impact on melt in the accumulation area. A background ice albedo field derived from MODIS imagery improves the agreement between the modeled and observed SMB gradient along the K-transect. The effect of enhanced meltwater retention and refreezing is a decrease of the albedo due to an increase in snow grain size. As a secondary effect of refreezing the snowpack is heated, enhancing melt and further lowering the albedo. Especially in a warmer climate this process is important, since it reduces the refreezing potential of the firn layer that covers the Greenland Ice Sheet.

  13. IASI's sensitivity to near-surface carbon monoxide (CO): Theoretical analyses and retrievals on test cases

    Science.gov (United States)

    Bauduin, Sophie; Clarisse, Lieven; Theunissen, Michael; George, Maya; Hurtmans, Daniel; Clerbaux, Cathy; Coheur, Pierre-François

    2017-03-01

    Separating concentrations of carbon monoxide (CO) in the boundary layer from the rest of the atmosphere with nadir satellite measurements is of particular importance to differentiate emission from transport. Although thermal infrared (TIR) satellite sounders are considered to have limited sensitivity to the composition of the near-surface atmosphere, previous studies show that they can provide information on CO close to the ground in case of high thermal contrast. In this work we investigate the capability of IASI (Infrared Atmospheric Sounding Interferometer) to retrieve near-surface CO concentrations, and we quantitatively assess the influence of thermal contrast on such retrievals. We present a 3-part analysis, which relies on both theoretical forward simulations and retrievals on real data, performed for a large range of negative and positive thermal contrast situations. First, we derive theoretically the IASI detection threshold of CO enhancement in the boundary layer, and we assess its dependence on thermal contrast. Then, using the optimal estimation formalism, we quantify the role of thermal contrast on the error budget and information content of near-surface CO retrievals. We demonstrate that, contrary to what is usually accepted, large negative thermal contrast values (ground cooler than air) lead to a better decorrelation between CO concentrations in the low and the high troposphere than large positive thermal contrast (ground warmer than the air). In the last part of the paper we use Mexico City and Barrow as test cases to contrast our theoretical predictions with real retrievals, and to assess the accuracy of IASI surface CO retrievals through comparisons to ground-based in-situ measurements.

  14. Highly Sensitive Surface Enhanced Raman Spectroscopy from Ag Nanoparticles Decorated Graphene Sheet

    Directory of Open Access Journals (Sweden)

    Hui Song

    2014-01-01

    Full Text Available Surface enhanced Raman spectroscopy (SERS is a powerful analytical technique and has been most intensively studied. In this work, electroless deposition is proposed for Ag nanoparticles (NPs decorated on chemical vapor deposition (CVD growth graphene sheets (GS to create hybrid SERS substrate. From three aspects of size distribution, morphology, and coverage, Ag NPs controllable decoration on GS and SERS enhancement factors of the hybrid SERS substrate is investigated. 200–300 times enhanced SERS intensities are detected from the Ag NPs on GS hybrid as compared to pure GS. Controllable decoration is crucial for improving SERS enhancement factors βEF, because βEF from quasi cubic Ag NPs on GS is 6.53 times stronger than that from spheric one; 1.6 times βEF is detected while the Ag NPs size distribution is reduced to half, and when the coverage is doubled, βEF is nearly doubled. This controllable Ag NPs/GS hybrid is capable of serving as a high performance SERS substrate for efficient chemical and biological sensing applications.

  15. Sensitivity of summer precipitation to tropical sea surface temperatures over East Asia in the GRIMs GMP

    Science.gov (United States)

    Chang, Eun-Chul; Yeh, Sang-Wook; Hong, Song-You; Wu, Renguang

    2013-05-01

    In this study, uncoupled atmospheric general circulation model experiments are conducted to examine the sensitivity of tropical Ocean basins from the Indian Ocean to the tropical Pacific Ocean on the summer precipitation variability over East Asia. It is remarkable that the Indian Ocean basin sea surface temperature (SST) and the tropical Pacific basin SST act on summer precipitation variability over Northeast Asia and southern China quite differently. That is, SST warming in the Indian Ocean largely contributes to the increase in the amount of summer precipitation over East Asia, which is in contrast to the warming of the western tropical Pacific Ocean. Our further analysis indicates that an altered large-scale atmospheric circulation over the western tropical Pacific contributes to contrasting atmospheric motion over East Asia due to the tropics-East Asia teleconnections, which results in changes in the amount of summer precipitation due to the warming of the Indian and western tropical Pacific Oceans.

  16. Measuring Surface Pressure on Rotating Compressor Blades Using Pressure Sensitive Paint

    Directory of Open Access Journals (Sweden)

    Markus Pastuhoff

    2016-03-01

    Full Text Available Pressure sensitive paint (PSP was used to measure pressure on the blades of a radial compressor with a 51 mm inlet diameter rotating at speeds up to 50 krpm using the so called lifetime method. A diode laser with a scanning-mirror system was used to illuminate the paint and the luminescent lifetime was registered using a photo multiplier. With the described technique the surface-pressure fields were acquired for eight points in the compressor map, useful for general understanding of the flow field and for CFD validation. The PSP was of so called fast type, which makes it possible to observe pressure variations with frequencies up to several kHz. Through frequency spectrum analysis we were able to detect the pulsating flow frequency when the compressor was driven to surge.

  17. Surface engineering of ZnO nanostructures for semiconductor-sensitized solar cells.

    Science.gov (United States)

    Xu, Jun; Chen, Zhenhua; Zapien, Juan Antonio; Lee, Chun-Sing; Zhang, Wenjun

    2014-08-20

    Semiconductor-sensitized solar cells (SSCs) are emerging as promising devices for achieving efficient and low-cost solar-energy conversion. The recent progress in the development of ZnO-nanostructure-based SSCs is reviewed here, and the key issues for their efficiency improvement, such as enhancing light harvesting and increasing carrier generation, separation, and collection, are highlighted from aspects of surface-engineering techniques. The impact of other factors such as electrolyte and counter electrodes on the photovoltaic performance is also addressed. The current challenges and perspectives for the further advance of ZnO-based SSCs are discussed. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. On understanding the relationship between structure in the potential surface and observables in classical dynamics: A functional sensitivity analysis approach

    Science.gov (United States)

    Judson, Richard S.; Rabitz, Herschel

    1987-04-01

    The relationship between structure in the potential surface and classical mechanical observables is examined by means of functional sensitivity analysis. Functional sensitivities provide maps of the potential surface, highlighting those regions that play the greatest role in determining the behavior of observables. A set of differential equations for the sensitivities of the trajectory components are derived. These are then solved using a Green's function method. It is found that the sensitivities become singular at the trajectory turning points with the singularities going as η-3/2, with η being the distance from the nearest turning point. The sensitivities are zero outside of the energetically and dynamically allowed region of phase space. A second set of equations is derived from which the sensitivities of observables can be directly calculated. An adjoint Green's function technique is employed, providing an efficient method for numerically calculating these quantities. Sensitivity maps are presented for a simple collinear atom-diatom inelastic scattering problem and for two Henon-Heiles type Hamiltonians modeling intramolecular processes. It is found that the positions of the trajectory caustics in the bound state problem determine regions of the highest potential surface sensitivities. In the scattering problem (which is impulsive, so that ``sticky'' collisions did not occur), the positions of the turning points of the individual trajectory components determine the regions of high sensitivity. In both cases, these lines of singularities are superimposed on a rich background structure. Most interesting is the appearance of classical interference effects. The interference features in the sensitivity maps occur most noticeably where two or more lines of turning points cross. The important practical motivation for calculating the sensitivities derives from the fact that the potential is a function, implying that any direct attempt to understand how local

  19. Metal-organic frameworks supported surface-imprinted nanoparticles for the sensitive detection of metolcarb.

    Science.gov (United States)

    Qian, Kun; Deng, Qiliang; Fang, Guozhen; Wang, Junping; Pan, Mingfei; Wang, Shuo; Pu, Yuehong

    2016-05-15

    A novel approach to synthesize molecularly imprinted polymer (MIP) nanoparticles using a MIL-101 support (a type of metal-organic framework) is reported herein for the first time; the sample is referred as MIL@MIP. The nanoparticles were well distributed within the polymer film, and exhibit an octahedral shape, satisfied thermal stability, and a high specific surface area (SSA) of 1579.43 m(2)g(-1). The adsorption behavior of MIL@MIP toward metolcarb in aqueous solution was subsequently examined. The synthesized MIL@MIP displayed satisfactory high transfer mass rates and a high selective adsorption affinity for metolcarb. Based on these results, a quartz crystal microbalance (QCM) sensor based on MIL@MIP was subsequently constructed and examined for the sensitive detection of metolcarb. Under optimal conditions, the detection limit of the system assessed in pear juice was 0.0689 mg L(-1) within a linear concentration range of 0.1-0.9 mg L(-1). MIL@MIP-QCM system combines the advantages of MIL-101 and molecularly imprinted technology (MIT), thereby achieving high detection sensitivity and selectivity. The current findings suggest the potential of MIL@MIP for detecting trace level pesticides and veterinary drugs for food safety and environmental control.

  20. Two Dimensional Array of Piezoresistive Nanomechanical Membrane-Type Surface Stress Sensor (MSS with Improved Sensitivity

    Directory of Open Access Journals (Sweden)

    Nico F. de Rooij

    2012-11-01

    Full Text Available We present a new generation of piezoresistive nanomechanical Membrane-type Surface stress Sensor (MSS chips, which consist of a two dimensional array of MSS on a single chip. The implementation of several optimization techniques in the design and microfabrication improved the piezoresistive sensitivity by 3~4 times compared to the first generation MSS chip, resulting in a sensitivity about ~100 times better than a standard cantilever-type sensor and a few times better than optical read-out methods in terms of experimental signal-to-noise ratio. Since the integrated piezoresistive read-out of the MSS can meet practical requirements, such as compactness and not requiring bulky and expensive peripheral devices, the MSS is a promising transducer for nanomechanical sensing in the rapidly growing application fields in medicine, biology, security, and the environment. Specifically, its system compactness due to the integrated piezoresistive sensing makes the MSS concept attractive for the instruments used in mobile applications. In addition, the MSS can operate in opaque liquids, such as blood, where optical read-out techniques cannot be applied.

  1. Development, validation and application of a sensitive analytical method for residue determination and dissipation of imidacloprid in sugarcane under tropical field condition.

    Science.gov (United States)

    Ramasubramanian, T; Paramasivam, M; Nirmala, R

    2016-06-01

    A simple and sensitive analytical method has been developed and validated for the determination of trace amounts of imidacloprid in/on sugarcane sett, stalk and leaf. The method optimized in the present study requires less volume of organic solvent and time. Hence, this method is suitable for high-throughput analyses involving large number of samples. The limit of detection (LOD) and limit of quantification (LOQ) of the method were 0.003 and 0.01 mg/kg, respectively. The recovery and relative standard deviation were more than 93 % and less than 4 %, respectively. Thus, it is obvious that the analytical method standardized in this study is more precise and accurate enough to determine the residues of imidacloprid in sugarcane sett, stalk and leaf. The dissipation and translocation of imidacloprid residues from treated cane setts to leaf and stalk were studied by adopting this method. In sugarcane setts, the residues of imidacloprid persisted up to 120 days with half-life of 15.4 days at its recommended dose (70 g a.i./ha). The residues of imidacloprid were found to be translocated from setts to stalk and leaf. The imidacloprid residues were detected up to 105 days in both leaf and stalk. Dipping of sugarcane setts in imidacloprid at its recommended dose may result in better protection of cane setts and established crop because of higher initial deposit (>100 mg/kg) and longer persistence (>120 days).

  2. Polydopamine Thin Films as Protein Linker Layer for Sensitive Detection of Interleukin-6 by Surface Plasmon Enhanced Fluorescence Spectroscopy.

    Science.gov (United States)

    Toma, Mana; Tawa, Keiko

    2016-08-31

    Polydopamine (PDA) thin films are introduced to the surface modification of biosensor surfaces utilizing surface plasmon enhanced fluorescence spectroscopy (SPFS) as the linker layer of capture antibody on to the sensor surfaces. The capture antibody can be directly attached to the sensor surface without using any coupling agent by functionalizing the gold sensor surface with PDA thin films. The PDA coating is performed by a single-step preparation process by applying the dopamine solution on the sensor surface, which requires an extremely short incubation time (10 min). The real-time in situ measurement of the adsorption kinetics of the capture antibody onto the PDA-coated sensor surface is studied by surface plasmon resonance (SPR) spectroscopy. It reveals that the immobilization of capture antibody immediately occurs after introduction of a solution containing capture antibody, and the sensor surface is fully covered with the capture antibody. The sensitive detection of the cytokine marker interleukin-6 (IL-6) is performed by SPFS using a sandwich assay format with fluorescently labeled detection antibody. The sensor chips functionalized by PDA chemistry exhibited sensitive sensor responses with low nonspecific adsorption of the detection antibody onto the sensor surface. The detection limit of IL-6 with the developed SPFS biosensor is determined to be 2 pg/mL (100 fM), which is within the range of the diagnostic criteria. Our observation elucidates the remarkable utility of PDA coatings for chemical modification of the metallic sensor surfaces by a simple, brief, and inexpensive manner.

  3. O2 Plasma Etching and Antistatic Gun Surface Modifications for CNT Yarn Microelectrode Improve Sensitivity and Antifouling Properties.

    Science.gov (United States)

    Yang, Cheng; Wang, Ying; Jacobs, Christopher B; Ivanov, Ilia N; Venton, B Jill

    2017-05-16

    Carbon nanotube (CNT) based microelectrodes exhibit rapid and selective detection of neurotransmitters. While different fabrication strategies and geometries of CNT microelectrodes have been characterized, relatively little research has investigated ways to selectively enhance their electrochemical properties. In this work, we introduce two simple, reproducible, low-cost, and efficient surface modification methods for carbon nanotube yarn microelectrodes (CNTYMEs): O2 plasma etching and antistatic gun treatment. O2 plasma etching was performed by a microwave plasma system with oxygen gas flow and the optimized time for treatment was 1 min. The antistatic gun treatment flows ions by the electrode surface; two triggers of the antistatic gun was the optimized number on the CNTYME surface. Current for dopamine at CNTYMEs increased 3-fold after O2 plasma etching and 4-fold after antistatic gun treatment. When the two treatments were combined, the current increased 12-fold, showing the two effects are due to independent mechanisms that tune the surface properties. O2 plasma etching increased the sensitivity due to increased surface oxygen content but did not affect surface roughness while the antistatic gun treatment increased surface roughness but not oxygen content. The effect of tissue fouling on CNT yarns was studied for the first time, and the relatively hydrophilic surface after O2 plasma etching provided better resistance to fouling than unmodified or antistatic gun treated CNTYMEs. Overall, O2 plasma etching and antistatic gun treatment improve the sensitivity of CNTYMEs by different mechanisms, providing the possibility to tune the CNTYME surface and enhance sensitivity.

  4. Analytical and numerical calculation of magnetic field distribution in the slotted air-gap of tangential surface permanent-magnet motors

    Directory of Open Access Journals (Sweden)

    Boughrara Kamel

    2009-01-01

    Full Text Available This paper deals with the analytical and numerical analysis of the flux density distribution in the slotted air gap of permanent magnet motors with surface mounted tangentially magnetized permanent magnets. Two methods for magnetostatic field calculations are developed. The first one is an analytical method in which the effect of stator slots is taken into account by modulating the magnetic field distribution by the complex relative air gap permeance. The second one is a numerical method using 2-D finite element analysis with consideration of Dirichlet and anti-periodicity (periodicity boundary conditions and Lagrange Multipliers for simulation of movement. The results obtained by the analytical method are compared to the results of finite-element analysis.

  5. Strand Invasion Based Amplification (SIBA®: a novel isothermal DNA amplification technology demonstrating high specificity and sensitivity for a single molecule of target analyte.

    Directory of Open Access Journals (Sweden)

    Mark J Hoser

    Full Text Available Isothermal nucleic acid amplification technologies offer significant advantages over polymerase chain reaction (PCR in that they do not require thermal cycling or sophisticated laboratory equipment. However, non-target-dependent amplification has limited the sensitivity of isothermal technologies and complex probes are usually required to distinguish between non-specific and target-dependent amplification. Here, we report a novel isothermal nucleic acid amplification technology, Strand Invasion Based Amplification (SIBA. SIBA technology is resistant to non-specific amplification, is able to detect a single molecule of target analyte, and does not require target-specific probes. The technology relies on the recombinase-dependent insertion of an invasion oligonucleotide (IO into the double-stranded target nucleic acid. The duplex regions peripheral to the IO insertion site dissociate, thereby enabling target-specific primers to bind. A polymerase then extends the primers onto the target nucleic acid leading to exponential amplification of the target. The primers are not substrates for the recombinase and are, therefore unable to extend the target template in the absence of the IO. The inclusion of 2'-O-methyl RNA to the IO ensures that it is not extendible and that it does not take part in the extension of the target template. These characteristics ensure that the technology is resistant to non-specific amplification since primer dimers or mis-priming are unable to exponentially amplify. Consequently, SIBA is highly specific and able to distinguish closely-related species with single molecule sensitivity in the absence of complex probes or sophisticated laboratory equipment. Here, we describe this technology in detail and demonstrate its use for the detection of Salmonella.

  6. Chromatic analysis by monitoring unmodified silver nanoparticles reduction on double layer microfluidic paper-based analytical devices for selective and sensitive determination of mercury(II).

    Science.gov (United States)

    Meelapsom, Rattapol; Jarujamrus, Purim; Amatatongchai, Maliwan; Chairam, Sanoe; Kulsing, Chadin; Shen, Wei

    2016-08-01

    This study demonstrates chromatic analysis based on a simple red green blue (RGB) color model for sensitive and selective determination of mercury(II). The analysis was performed by monitoring the color change of a microfluidic Paper-based Analytical Device (µPAD). The device was fabricated by using alkyl ketene dimer (AKD)-inkjet printing and doped with unmodified silver nanoparticles (AgNPs) which were disintegrated when being exposed to mercury(II). The color intensity was detected by using an apparatus consisting of a digital camera and a homemade light box generating constant light intensity. A progressive increase in color intensity of the tested area on the µPAD (3.0mm) was observed with increasing mercury(II) concentration. The developed system enabled quantification of mercury(II) at low concentration with the detection limit of 0.001mgL(-1) (3 SD blank/slope of the calibration curve) and small sample volume uptake (2µL). The linearity range of the calibration curve in this technique was demonstrated from 0.05 to 7mgL(-1) (r(2)=0.998) with good precision (RSD less than 4.1%). Greater selectivity towards mercury(II) compared with potential interference ions was also observed. Furthermore, the percentage recoveries of spiked water samples were in an acceptable range which was in agreement with the values obtained from the conventional method utilizing cold vapor atomic absorption spectrometer (CVAAS). The proposed technique allows a rapid, simple, sensitive and selective analysis of trace mercury(II) in water samples.

  7. Sensitivity enhancement based on application of multi-pass interferometry in phase-sensitive surface plasmon resonance biosensor

    Science.gov (United States)

    Ho, H. P.; Yuan, W.; Wong, C. L.; Wu, S. Y.; Suen, Y. K.; Kong, S. K.; Lin, Chinlon

    2007-07-01

    A novel design of multi-pass surface plasmon resonance (SPR) biosensor with differential phase interrogation based on multi-pass interferometry is presented. This new configuration provides an intrinsic phase amplification effect of over twofold by placing the SPR sensor head in a signal arm of the interferometer so that the interrogating optical beam will traverse the sensor surface infinite number of times. Experimental interferometers based on the Michelson and Fabry-Perot configurations have been employed to experimentally verify this amplification effect when they were compared with Mach-Zehnder configuration, results obtained from salt-water mixtures, antibody-antigen, and protein-DNA binding reaction confirmed the expected phase measurement enhancement, thus leading to the possibility of direct detection of small sized bio-molecules using SPR.

  8. Sensitive Detection of Melamine in Infant Milk and Coffee Mate by a Buffer Mediated Extraction and HPLC-PDA Analytical Method

    Directory of Open Access Journals (Sweden)

    Maryam Rezai

    2014-12-01

    Full Text Available Melamine is a potentially hazardous compound and one of the major concerns especially in dairy products and pet foods. In the present study a sensitive, simple and reliable method for extraction and determination of melamine in infant milk and coffee mate has been developed. This method consists of an initial extraction in buffer media prepared by formic acid and sodium formate, followed by protein precipitation by acetonitrile and dichloromethane. The chromatographic separation was carried out on a 100-Nucleosil -NH2 column with an optimized acetonitrile-water (80:20 v/v as a mobile phase and with a photodiode-array detector. The analytical method was validated according to the validation parameters, such as, selectivity, linearity (0.08-10 µg/mL, with r2= 0.9998 and 0.05-10 µg/mL with r2= 0.9997, precision (intra-day 0.52-2.66%, 0.78-1.20; inter-day 2.96-4.20%, 2.80-3.00% and accuracy (92-102%, 92-100% for powdered milk and coffee mates respectively. The limits of detection and quantization were 0.02, 0.08 µg/mL for powdered milk and 0.01, 0.05 µg/mL for coffee mate, respectively.

  9. A study of charge transfer kinetics in dye-sensitized surface conductivity solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Friedrich, Dennis

    2011-05-15

    The efficiency of the quasi-solid-state dye-sensitized solar cell developed by Junghaenel and Tributsch, the so-called Nano Surface Conductivity Solar Cell (NSCSC), was improved from 2% to 3.5% introducing a compact TiO{sub 2} underlayer, modifying the surface of the mesoporous TiO{sub 2} electrode, optimizing the deposition process of the electrolyte film, and replacing the platinum counter electrode by a carbon layer. Space-resolved photocurrent images revealed the importance of a homogeneous distribution of the electrolyte film. An uneven dispersion led to localized areas of high and low photocurrents, whereas the latter were attributed to an insufficient concentration of the redox couple. Impedance spectroscopy was performed on cells containing different concentrations of the redox couple. By modeling the spectra using an equivalent circuit with a transmission line of resistive and capacitive elements, the characteristic parameters of electron transport in the TiO{sub 2}, such as diffusion length and electron lifetime were obtained. The measurements indicated that the transport of the positive charge to the counter electrode is the main process limiting the efficiency of the cells. Excess charge carrier decay in functioning devices was analyzed by contactless transient photoconductance measurements in the microwave frequency range (TRMC). The lifetime of the photogenerated charge carriers was observed to decrease with increasing applied potential, reaching its maximum close to the opencircuit potential of the cell, where the photocurrent density was minimal, i.e. the potential dependent decay observed was limited by the injection of electrons into the front contact. The functioning of this NSCSC indicated that the transport of the positive charge occurs by solid-state diffusion at the surface of the TiO{sub 2} particles. TRMC measurements on subset devices in the form of sensitized TiO{sub 2} layers revealed charge carrier kinetics strongly dependent on the

  10. Effect of photoanode surface coverage by a sensitizer on the photovoltaic performance of titania based CdS quantum dot sensitized solar cells.

    Science.gov (United States)

    Prasad, Rajendra M B; Pathan, Habib M

    2016-04-08

    In spite of the promising design and architecture, quantum dot sensitized solar cells (QDSSCs) have a long way to go before they attain the actual projected photoconversion efficiencies. Such an inferior performance displayed by QDSSCs is primarily because of many unwanted recombination losses of charge carriers at various interfaces of the cell. Electron recombination due to back electron transfer at the photoanode/electrolyte interface is an important one that needs to be addressed, to improve the efficiency of these third generation nanostructured solar cells. The present work highlights the importance of conformal coverage of CdS quantum dots (QDs) on the surface of the nanocrystalline titania photoanode in arresting such recombinations, leading to improvement in the performance of the cells. Using the successive ionic layer adsorption and reaction (SILAR) process, photoanodes are subjected to different amounts of CdS QD sensitization by varying the number of cycles of deposition. The sensitized electrodes are characterized using UV-visible spectroscopy, cyclic voltammetry and transmission electron microscopy to evaluate the extent of surface coverage of titania electrodes by QDs. Sandwich solar cells are then fabricated using these electrodes and characterized employing electrochemical impedance spectroscopy and J-V characteristics. It is observed that maximum solar cell efficiency is obtained for photoanodes with conformal coating of QDs and any further deposition of sensitizer leads to QD aggregation and so reduces the performance of the solar cells.

  11. Optimal pressure-sensitive cuts for surface acoustic waves on langasite

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The crystal langasite manifests its unique advantages and potentials for high temperature applications due to a high electromechanical coupling coefficient, temperature compensated orientations for surface acoustic wave (SAW), and temperature stability. In order to analyze the pressure-induced frequency shift in SAW resonator type sensors at high temperature, this paper presents the electroelastic wave equations employing the effective material constants for small vibrations superimposed on biases originated from homogeneous temperature and external pressure fields in the Lagrangian description. Incorporated with the first-order perturbation integration, a model including both the mechanical and electrical perturbation items originating from thermal biases and small pressure fields is proposed. This universal model is suitable for substrate with high piezoelectricity and can be applied at either room temperature or high temperature circumstance. The criteria of optimal cuts for SAW pressure sensitivity, I.e., high electromechanical coupling coefficient and low temperature coefficient of delay, are proposed. A thorough investigation in trebly rotated cuts has shown that optimal pressure sensitive crystallographic areas can be obtained. The areas suitable for pressure sensors at room temperature are defined with Euler anglesThe areas suitable for pressure sensors at high temperature are defined with Euler anglesΩ1: φ= 0°―0.6°,θ= 144.4°―145.8°, ψ= 23.2°―24.1°,Ω2: φ=59.4°―61°,θ= 34.2°―36.2°, ψ= 24.1°―22.3°,Ω3: φ=119°―120°,θ = 143.8°―145.5°, ψ= 22.3°―23.5°.The areas suitable for pressure sensors at high temperature are defined with Euler anglesI:φ= 8°―30°,θ= 24°―36°,ψ= 4°―25°,II:φ = 30°―55°,θ= 144°―158°,ψ= 4°―28°.A set of experiments employing LGS (0, 150°, 22°) and (0, 90°, 0) has been performed to check the validity of the proposed calculation. The experimental relative sensitivity is

  12. Assessing total nitrogen in surface-water samples--precision and bias of analytical and computational methods

    Science.gov (United States)

    Rus, David L.; Patton, Charles J.; Mueller, David K.; Crawford, Charles G.

    2013-01-01

    concentrations up to 750 mg/L (median of -4.4 percent). This lent support to the laboratory-experiment finding that some particulate nitrogen is sequestered during the digestion process, and demonstrated that negative TN-A bias was present in samples with very low suspended-sediment concentrations. At sediment concentrations above 750 mg/L, the negative TN-A bias became more likely and larger (median of -13.2 percent), suggesting a secondary mechanism of bias, such as reagent limitation. From a geospatial perspective, trends in TN-A bias were not explained by selected basin characteristics. Though variable, TN-K bias generally was positive in the synoptic-field study (median of 3.1 percent), probably as a result of the reduction of nitrate. Three alternative approaches for assessing TN in surface water were evaluated for their impacts on existing and future sampling programs. Replacing TN-A with TN-C would remove the bias from subsequent data, but this approach also would introduce discontinuity in historical records. Replacing TN-K with TN-C would lead to the removal of positive bias in TN-K in the presence of elevated nitrate. However, in addition to the issues that may arise from a discontinuity in the data record, this approach may not be applicable to regulatory programs that require the use of total Kjeldahl nitrogen for stream assessment. By adding TN-C to existing TN-A or TN-K analyses, historical-data continuity would be preserved and the transitional period could be used to minimize the impact of bias on data analyses. This approach, however, imposes the greatest burdens on field operations and in terms of analytical costs. The variation in these impacts on different sampling programs will challenge U.S. Geological Survey scientists attempting to establish uniform standards for TN sample collection and analytical determinations.

  13. Simulating increased Lamb wave detection sensitivity of surface bonded fiber Bragg grating

    Science.gov (United States)

    Wee, J.; Hackney, D. A.; Bradford, P. D.; Peters, K. J.

    2017-04-01

    Fiber Bragg grating (FBG) sensors are excellent transducers for collecting ultrasonic wave signals for structural health monitoring (SHM). Typically, FBG sensors are directly bonded to the surface of a structure to detect signals. Unfortunately, demodulating relevant information from the collected signal demands a high signal-to-noise ratio because the structural ultrasonic waves have low amplitudes. Our previous experimental work demonstrated that the optical fiber could be bonded at a distance away from the FBG location, referred to here as remote bonding. This remote bonding technique increased the output signal amplitude compared to the direct bonding case, however the mechanism causing the increase was not explored. In this work, we simulate the previous experimental work through transient analysis based on the finite element method, and the output FBG response is calculated through the transfer matrix method. The model is first constructed without an adhesive to assume an ideal bonding condition, investigating the difference in excitation signal coherence along the FBG length between the two bonding configurations. A second model is constructed with an adhesive to investigate the effect of the presence of the adhesive around the FBG. The results demonstrate that the amplitude increase is originated not from the excitation signal coherence, but from the shear lag effect which causes immature signal amplitude development in the direct bonding case compared to the remote bonding case. The results also indicate that depending on the adhesive properties the surface-bonded optical fiber manifests varying resonant frequency, therefore resulting in a peak amplitude response when the input excitation frequency is matched. This work provides beneficial reference for selecting adhesive and calibrating sensing system for maximum ultrasonic detection sensitivity using the FBG sensor.

  14. Sensitivity Analysis of Grain Surface Chemistry to Binding Energies of Ice Species

    Science.gov (United States)

    Penteado, E. M.; Walsh, C.; Cuppen, H. M.

    2017-07-01

    Advanced telescopes, such as ALMA and the James Webb Space Telescope, are likely to show that the chemical universe may be even more complex than currently observed, requiring astrochemical modelers to improve their models to account for the impact of new data. However, essential input information for gas-grain models, such as binding energies of molecules to the surface, have been derived experimentally only for a handful of species, leaving hundreds of species with highly uncertain estimates. We present in this paper a systematic study of the effect of uncertainties in the binding energies on an astrochemical two-phase model of a dark molecular cloud, using the rate equations approach. A list of recommended binding energy values based on a literature search of published data is presented. Thousands of simulations of dark cloud models were run, and in each simulation a value for the binding energy of hundreds of species was randomly chosen from a normal distribution. Our results show that the binding energy of H2 is critical for the surface chemistry. For high binding energies, H2 freezes out on the grain forming an H2 ice. This is not physically realistic, and we suggest a change in the rate equations. The abundance ranges found are in reasonable agreement with astronomical ice observations. Pearson correlation coefficients revealed that the binding energy of HCO, HNO, CH2, and C correlate most strongly with the abundance of dominant ice species. Finally, the formation route of complex organic molecules was found to be sensitive to the branching ratios of H2CO hydrogenation.

  15. Sensitivity of tropical cyclone characteristics to the radial distribution of sea surface temperature

    Indian Academy of Sciences (India)

    Deepika Rai; S Pattnaik; P V Rajesh

    2016-06-01

    Sea Surface Temperature (SST) is crucial for the development and maintenance of a tropical cyclone(TC) particularly below the storm core region. However, storm data below the core region is the mostdifficult to obtain, hence it is not clear yet that how sensitive the radial distribution of the SST impactthe storm characteristic features such as its inner-core structures, translational speed, track, rainfalland intensity particularly over the Bay of Bengal. To explore the effects of radial SST distributionon the TC characteristics, a series of numerical experiments were carried out by modifying the SSTat different radial extents using two-way interactive, triply-nested, nonhydrostatic Advanced WeatherResearch and Forecast (WRF-ARW) model. It is found that not only the SST under the eyewall (coreregion) contribute significantly to modulate storm track, translational speed and intensity, but also thoseoutside the eyewall region (i.e., 2–2.5 times the radius of maximum wind (RMW)) play a vital role indefining the storm’s characteristics and structure. Out of all the simulated experiments, storm wherethe positive radial change of SST inducted within the 75 km of the storm core (i.e., P75) produced thestrongest storm. In addition, N300 (negative radial changes at 300 km) produced the weakest storm.Further, it is found that SST, stronger within 2–2.5 times of the RMW for P75 experiment, plays adominant role in maintaining 10 m wind speed (WS10), surface entropy flux (SEF) and upward verticalvelocity (w) within the eyewall with warmer air temperature (T) and equivalent potential temperature(θe) within the storm’s eye compared to other experiments.

  16. An accurate, analytical, and technology-mapped definition of the surface potential at threshold and a new postulate for the threshold voltage of MOSFETs

    Science.gov (United States)

    Sarkar, Vaskar; Dutta, Aloke K.

    2006-11-01

    A novel approach of defining the threshold voltage for long channel MOSFETs has been presented in this paper, where it has been proposed that it corresponds to the gate-to-source voltage for which the drift and diffusion components of the total drain current become equal to each other. In order to avoid the greater computation time associated with the numerical solution of these two components, an analytical expression of the surface potential, corresponding to the threshold condition, is given here, which has the same functional form as the one proposed by Tsividis. The fuzzy parameter n, appearing in this expression of the surface potential, is expressed as a function of the substrate doping density ( NA) and the oxide thickness ( tox). The threshold voltage values, obtained analytically from the relation between the surface potential at the threshold condition and the closed-form technology-mapped expression of the fuzzy parameter n, show an excellent match with those obtained from SILVACO simulations for a wide range of NA and tox, with the maximum error being only about 4%. The comparison of the percent error values of the threshold voltage obtained from this proposed model with those obtained from the other two recently proposed methods, all with respect to SILVACO simulation results, further verifies the validity of our completely analytical, mathematically simple, and straight-forward approach, proposed in this work here.

  17. Imaging natural and artificial demineralization on dentin surfaces with polarization sensitive optical coherence tomography.

    Science.gov (United States)

    Manesh, Saman K; Darling, Cynthia L; Fried, Daniel

    2008-01-01

    The purpose of this study was to assess the potential of polarization sensitive optical coherence tomography (PS-OCT) to measure non-destructively the severity of natural and artificial caries lesions in dentin and determine the efficacy of intervention with anti-caries agents. Although several studies have demonstrated the utility of PS-OCT to image caries lesions in enamel and to quantify the lesion severity, only a few studies have focused on lesions in dentin. In this study images of natural root caries lesions on extracted human teeth were acquired with PS-OCT. In addition artificial lesions were produced in dentin after 12 days of exposure to a demineralization solution at a pH of 5.0. Before exposure, three incisions were made on the sample surfaces using Er:YAG laser irradiation and selected areas were treated with topical fluoride. PS-OCT images were acquired using a high power (45-mw) 1310-nm superluminescent diode with a bandwidth of 35-nm. PS-OCT was able to measure demineralization in dentin to a depth of ~ 1 mm. Polarized light microscopy and microradiography were used to measure lesion severity on histological thin sections for comparison. PS-OCT successfully measured the inhibition of demineralization by topical fluoride. Er:YAG laser irradiation did not significantly increase or decrease the rate of dentin demineralization.

  18. Sensitivities of NOx transformation and the effects on surface ozone and nitrate

    Directory of Open Access Journals (Sweden)

    H. Lei

    2013-08-01

    Full Text Available As precursors for tropospheric ozone and nitrate aerosols, Nitrogen oxides (NOx in present atmosphere and its transformation in responding to emission and climate perturbations are studied by CAM-Chem model and air quality measurements including National Emission Inventory (NEI, Clean Air Status and Trends Network (CASTNET and Environmental Protection Agency Air Quality System (EPA AQS. It is found that not only the surface ozone formation but also the nitrate formation is associated with the relative emissions of NOx and volatile organic compounds (VOC. Due to the availability of VOC and associated NOx titration, ozone productions in industrial regions increase in warmer conditions and slightly decrease against NOx emission increase, which is converse to the response in farming region. The decrease or small increase in ozone concentrations over industrial regions result in the responded nitrate increasing rate staying above the increasing rate of NOx emissions. It is indicated that ozone concentration change is more directly affected by changes in climate and precursor emissions, while nitrate concentration change is also affected by local ozone production types and their seasonal transfer. The sensitivity to temperature perturbations shows that warmer climate accelerates the decomposition of odd nitrogen (NOy during the night. As a result, the transformation rate of NOx to nitrate decreases. Examinations on the historical emission and air quality records on typical pollution areas further confirm the conclusion drawn from modeling experiments.

  19. In-situ surface sensitive X-ray investigations of quench condensed thin metal films

    Energy Technology Data Exchange (ETDEWEB)

    Markert, Christian; Luetzenkirchen-Hecht, Dirk; Gertz, Sascha; Frahm, Ronald [Bergische Universitaet Wuppertal, Fachbereich C / Abteilung Physik, Gaussstrasse 20, 42119 Wuppertal (Germany)

    2007-07-01

    We report of ultrahigh vacuum (UHV) experiments on ultra thin Au, Bi and Pb films (thickness less than 10 nm) deposited on atomically flat float-glass substrates which are held at cryogenic temperatures down to 10 K. For deposition temperatures below 100 K the formation of highly disordered or even amorphous metal films can be expected, because thermally activated diffusion of the ad atoms should be inhibited. An UHV chamber was constructed which is suited for grazing incidence X-ray experiments during the quench condensation of the metal films. Various X-ray methods were used for the in-situ investigation of the films growth and their structural evolution with the thickness and an subsequent annealing process. EXAFS (Extended X-ray Absorption Fine Structure) in reflection is used to study the local structure of the films. Furthermore specular and non-specular X-ray reflectivity measurements were performed to get information about the films density and surface roughness parameters (correlation length, hurst parameter etc.). In addition in situ resistivity measurements which are sensitive towards changes of the films microstructure were performed in parallel to the X-ray experiments.

  20. Comparison of unsteady pressure fields on turrets with different surface features using pressure-sensitive paint

    Science.gov (United States)

    Gordeyev, Stanislav; De Lucca, Nicholas; Jumper, Eric J.; Hird, Kyle; Juliano, Thomas J.; Gregory, James W.; Thordahl, James; Wittich, Donald J.

    2014-01-01

    Spatially temporally resolved unsteady pressure fields on a surface of a hemisphere-on-cylinder turret with either a flat or a conformal window with realistic features such as gaps and "smile" cutouts were characterized using fast-response pressure-sensitive paint at M = 0.33 for several window viewing angles. Various statistical properties of pressure fields were computed, and geometry effects on the unsteady pressure fields were analyzed and discussed. Proper orthogonal decomposition was also used to extract dominant pressure modes and corresponding temporal coefficients and to analyze and compare instantaneous pressure structures for different turret geometric features and the window viewing angles. An unsteady separation off the turret and a recirculation region downstream of the turret were identified as dominant sources of the unsteady pressure. It was found that while all geometric features affected the unsteady pressure field, the "smiles," positioned spanwise-symmetrically on both sides of the turret, were the leading cause of these changes, followed by the looking forward flat window. The gaps, the side- and the back-looking flat window introduced only small local changes.

  1. Enhanced Sensitivity of Surface Acoustic Wave-Based Rate Sensors Incorporating Metallic Dot Arrays

    Directory of Open Access Journals (Sweden)

    Wen Wang

    2014-02-01

    Full Text Available A new surface acoustic wave (SAW-based rate sensor pattern incorporating metallic dot arrays was developed in this paper. Two parallel SAW delay lines with a reverse direction and an operation frequency of 80 MHz on a same X-112°Y LiTaO3 wafer are fabricated as the feedback of two SAW oscillators, and mixed oscillation frequency was used to characterize the external rotation. To enhance the Coriolis force effect acting on the SAW propagation, a copper (Cu dot array was deposited along the SAW propagation path of the SAW devices. The approach of partial-wave analysis in layered media was referred to analyze the response mechanisms of the SAW based rate sensor, resulting in determination of the optimal design parameters. To improve the frequency stability of the oscillator, the single phase unidirectional transducers (SPUDTs and combed transducer were used to form the SAW device to minimize the insertion loss and accomplish the single mode selection, respectively. Excellent long-term (measured in hours frequency stability of 0.1 ppm/h was obtained. Using the rate table with high precision, the performance of the developed SAW rate sensor was evaluated experimentally; satisfactory detection sensitivity (16.7 Hz∙deg∙s−1 and good linearity were observed.

  2. Sensitivity-Based Modeling of Evaluating Surface Runoff and Sediment Load using Digital and Analog Mechanisms

    Directory of Open Access Journals (Sweden)

    Olotu Yahaya

    2014-07-01

    Full Text Available Analyses of runoff- sediment measurement and evaluation using automated and convectional runoff-meters was carried out at Meteorological and Hydrological Station of Auchi Polytechnic, Auchi using two runoff plots (ABCDa and EFGHm of area 2m 2 each, depth 0.26 m and driven into the soil to the depth of 0.13m. Runoff depths and intensities were measured from each of the positioned runoff plot. Automated runoff-meter has a measuring accuracy of ±0.001l/±0.025 mm and rainfall depth-intensity was measured using tipping-bucket rainguage during the period of 14-month of experimentation. Minimum and maximum rainfall depths of 1.2 and 190.3 mm correspond to measured runoff depths (MRo of 0.0 mm for both measurement approaches and 60.4 mm and 48.9 mm respectively. Automated runoffmeter provides precise, accurate and instantaneous result over the convectional measurement of surface runoff. Runoff measuring accuracy for automated runoff-meter from the plot (ABCDa produces R 2 = 0.99; while R 2 = 0.96 for manual evaluation in plot (EFGHm. WEPP and SWAT models were used to simulate the obtained hydrological variables from the applied measurement mechanisms. The outputs of sensitivity simulation analysis indicate that data from automated measuring systems gives a better modelling index and such could be used for running robust runoff-sediment predictive modelling technique under different reservoir sedimentation and water management scenarios.

  3. Enhanced sensitivity of surface acoustic wave-based rate sensors incorporating metallic dot arrays.

    Science.gov (United States)

    Wang, Wen; Shao, Xiuting; Liu, Xinlu; Liu, Jiuling; He, Shitang

    2014-02-26

    A new surface acoustic wave (SAW)-based rate sensor pattern incorporating metallic dot arrays was developed in this paper. Two parallel SAW delay lines with a reverse direction and an operation frequency of 80 MHz on a same X-112°Y LiTaO3 wafer are fabricated as the feedback of two SAW oscillators, and mixed oscillation frequency was used to characterize the external rotation. To enhance the Coriolis force effect acting on the SAW propagation, a copper (Cu) dot array was deposited along the SAW propagation path of the SAW devices. The approach of partial-wave analysis in layered media was referred to analyze the response mechanisms of the SAW based rate sensor, resulting in determination of the optimal design parameters. To improve the frequency stability of the oscillator, the single phase unidirectional transducers (SPUDTs) and combed transducer were used to form the SAW device to minimize the insertion loss and accomplish the single mode selection, respectively. Excellent long-term (measured in hours) frequency stability of 0.1 ppm/h was obtained. Using the rate table with high precision, the performance of the developed SAW rate sensor was evaluated experimentally; satisfactory detection sensitivity (16.7 Hz∙deg∙s(-1)) and good linearity were observed.

  4. High-sensitivity molecular sensing using hollow-core photonic crystal fiber and surface-enhanced Raman scattering.

    Science.gov (United States)

    Yang, Xuan; Shi, Chao; Wheeler, Damon; Newhouse, Rebecca; Chen, Bin; Zhang, Jin Z; Gu, Claire

    2010-05-01

    A high-sensitivity molecular sensor using a hollow-core photonic crystal fiber (HCPCF) based on surface-enhanced Raman scattering (SERS) has been experimentally demonstrated and theoretically analyzed. A factor of 100 in sensitivity enhancement is shown in comparison to direct sampling under the same conditions. With a silver nanoparticle colloid as the SERS substrate and Rhodamine 6G as a test molecule, the lowest detectable concentration is 10(-10) M with a liquid-core photonic crystal fiber (LCPCF) probe, and 10(-8) M for direct sampling. The high sensitivity provided by the LCPCF SERS probe is promising for molecular detection in various sensing applications.

  5. Kinetics study of the CN + CH4 hydrogen abstraction reaction based on a new ab initio analytical full-dimensional potential energy surface.

    Science.gov (United States)

    Espinosa-Garcia, Joaquin; Rangel, Cipriano; Suleimanov, Yury V

    2017-07-26

    We have developed an analytical full-dimensional potential energy surface, named PES-2017, for the gas-phase hydrogen abstraction reaction between the cyano radical and methane. This surface is fitted using high-level ab initio information as input. Using the PES-2017 surface, a kinetics study was performed via two theoretical approaches: variational transition-state theory with multidimensional tunnelling (VTST-MT) and ring polymer molecular dynamics (RPMD). The results are compared with the experimental data. In the whole temperature range analysed, 300-1500 K, both theories agree within a factor of kinetic isotope effects are important, reproducing the scarce experimental evidence. The good agreement with the ab initio information used in the fitting process (self-consistency test) and with the kinetic behaviour in a wide temperature range gives confidence and strength to the new surface.

  6. Application of surface plasmon resonance for the detection of carbohydrates, glycoconjugates, and measurement of the carbohydrate-specific interactions: a comparison with conventional analytical techniques. A critical review.

    Science.gov (United States)

    Safina, Gulnara

    2012-01-27

    Carbohydrates (glycans) and their conjugates with proteins and lipids contribute significantly to many biological processes. That makes these compounds important targets to be detected, monitored and identified. The identification of the carbohydrate content in their conjugates with proteins and lipids (glycoforms) is often a challenging task. Most of the conventional instrumental analytical techniques are time-consuming and require tedious sample pretreatment and utilising various labeling agents. Surface plasmon resonance (SPR) has been intensively developed during last two decades and has received the increasing attention for different applications, from the real-time monitoring of affinity bindings to biosensors. SPR does not require any labels and is capable of direct measurement of biospecific interaction occurring on the sensing surface. This review provides a critical comparison of modern analytical instrumental techniques with SPR in terms of their analytical capabilities to detect carbohydrates, their conjugates with proteins and lipids and to study the carbohydrate-specific bindings. A few selected examples of the SPR approaches developed during 2004-2011 for the biosensing of glycoforms and for glycan-protein affinity studies are comprehensively discussed.

  7. Sensitivity of the last glacial inception to initial and surface conditions

    Energy Technology Data Exchange (ETDEWEB)

    Kubatzki, Claudia [Potsdam-Institut fuer Klimafolgenforschung e.V., Potsdam (Germany); Alfred-Wegener-Institut fuer Polar- und Meeresforschung, Bremerhaven (Germany); Claussen, Martin [Potsdam-Institut fuer Klimafolgenforschung e.V., Potsdam (Germany); Hamburg Univ. (Germany). Meteorologisches Inst.; Max-Planck-Institut fuer Meteorologie, Hamburg (Germany); Calov, Reinhard; Ganopolski, Andrey [Potsdam-Institut fuer Klimafolgenforschung e.V., Potsdam (Germany)

    2006-09-15

    We investigate the sensitivity of simulations of the last glacial inception (LGI) with respect to initial (size of the Greenland ice sheet) and surface (state of ocean/vegetation) conditions and two different CO{sub 2} reconstructions. Utilizing the CLIMBER-2 Earth system model, we obtain the following results: (a) ice-sheet expansion in North America at the end of the Eemian can be reduced or even completely suppressed when pre-industrial or Eemian ocean/vegetation is prescribed. (b) A warmer surrounding ocean and, in particular, a large Laurentide ice sheet reduce the size of the Greenland ice sheet before and during the LGI. (c) A changing ocean contributes much stronger to the expansion of the Laurentide ice sheet when we apply the CO{sub 2} reconstruction according to Barnola et al. (Nature 329:408-414, 1987) instead of Petit et al. (Nature 399:429-436, 1999). (d) In the fully coupled model, the CO{sub 2} reconstruction used has only a small impact on the simulated ice sheets but it does impact the course of the climatic variables. (e) For the Greenland ice sheet, two equilibrium states exist under the insolation and CO{sub 2} forcing at 128,000 years before present (128 kyear BP); the one with an ice sheet reduced by about one quarter as compared to its simulated pre-industrial size and the other with nearly no inland ice in Greenland. (f) Even the extreme assumption of no ice sheet in Greenland at the beginning of our transient simulations does not alter the simulated expansion of northern hemispheric ice sheets at the LGI. (orig.)

  8. Preparation of Smooth Surface TiO2 Photoanode for High Energy Conversion Efficiency in Dye-Sensitized Solar Cells

    OpenAIRE

    Sasipriya Kathirvel; Huei-Siou Chen; Chaochin Su; Hsiue-Hsyan Wang; Chung-Yen Li; Wen-Ren Li

    2013-01-01

    Dye-sensitized solar cells (DSSCs) based on a TiO2 photoanode have been considered as an alternative source in the field of renewable energy resources. In DSSCs, photoanode plays a key role to achieve excellent photo-to-electric conversion efficiency. The surface morphology, surface area, TiO2 crystal phase, and the dispersion of TiO2 nanoparticles are the most important factors influencing the properties of a photoanode. The smooth TiO2 surface morphology of the photoanode indicates closely ...

  9. An analytical solution for the elastic response to surface loads imposed on a layered, transversely isotropic and self-gravitating Earth

    DEFF Research Database (Denmark)

    Pan, E.; Chen, J.Y.; Bevis, M.

    2015-01-01

    the correctness of our solution and the implementation. We also calculate the load Love numbers (LLNs) of the PREM Earth for different degrees of the Legendre function for both isotropic and transversely isotropic, layered mantles with different core models, demonstrating for the first time the effect of Earth......We present an analytical solution for the elastic deformation of an elastic, transversely isotropic, layered and self-gravitating Earth by surface loads. We first introduce the vector spherical harmonics to express the physical quantities in the layered Earth. This reduces the governing equations...... to a linear system of equations for the expansion coefficients. We then solve for the expansion coefficients analytically under the assumption (i.e. approximation) that in the mantle, the density in each layer varies as 1/r (where r is the radial coordinate) while the gravity is constant and that in the core...

  10. Fabrication of an SPR Sensor Surface with Antifouling Properties for Highly Sensitive Detection of 2,4,6-Trinitrotoluene Using Surface-Initiated Atom Transfer Polymerization

    Directory of Open Access Journals (Sweden)

    Kiyoshi Toko

    2013-07-01

    Full Text Available In this study, we modified a surface plasmon resonance immunosensor chip with a polymer using surface-initiated atom transfer polymerization (SI-ATRP for the highly sensitive detection of 2,4,6-trinitrotoluene (TNT. To immobilize a TNT analogue on the polymer, mono-2-(methacryloyloxyethylsuccinate (MES, which has a carboxyl group, was used in this study. However, the anti-TNT antibody may adsorb non-specifically on the polymer surface by an electrostatic interaction because MES is negatively charged. Therefore, a mixed monomer with MES and diethylaminoethylmethacrylate (DEAEM, which has a tertiary amino group and is positively charged, was prepared to obtain electroneutrality for suppressing the nonspecific adsorption. The detection of TNT was performed by inhibition assay using the polymer surface. To ensure high sensitivity to TNT, the affinity between the surface and the antibody was optimized by controlling the density of the initiator for ATRP by mixing two types of self-assembled monolayer reagents. As a result, a limit of detection of 5.7 pg/mL (ppt for TNT was achieved using the optimized surface.

  11. An analytical solution to calculate bulk mole fractions for any number of components in aerosol droplets after considering partitioning to a surface layer

    Directory of Open Access Journals (Sweden)

    D. Topping

    2010-07-01

    Full Text Available Calculating the equilibrium composition of atmospheric aerosol particles, using all variations of Köhler theory, has largely assumed that the total solute concentrations define both the water activity and surface tension. Recently however, bulk to surface phase partitioning has been postulated as a process which significantly alters the predicted point of activation. In this paper, an analytical solution to calculate the removal of material from a bulk to a surface layer in aerosol particles has been derived using a well established and validated surface tension framework. The applicability to an unlimited number of components is possible via reliance on data from each binary system. Whilst assumptions regarding behaviour at the surface layer have been made to facilitate derivation, it is proposed that the framework presented can capture the overall impact of bulk-surface partitioning. Predictions made by the model across a range of surface active properties should be tested against measurements. The computational efficiency of using the solution presented in this paper is roughly a factor of 20 less than a similar iterative approach, a comparison with highly coupled approaches not available beyond a 3 component system.

  12. Nano-objects as biomaterials: immense opportunities, significant challenges and the important use of surface analytical methods

    Energy Technology Data Exchange (ETDEWEB)

    Baer, Donald R.; Shutthanandan, Vaithiyalingam

    2017-05-30

    Nano-sized objects are increasingly important as biomaterials and their surfaces play critical roles in determining their beneficial or deleterious behaviors in biological systems. Important characteristics of nanomaterials that impact their application in many areas are described with a strong focus on the importance of particle surfaces and surface characterization. Understanding aspects of the inherent nature of nano-objects and the important role that surfaces play in these applications is a universal need for any research or product development using such materials in biological applications. The role of surface analysis methods in collecting critical information about the nature of particle surfaces and physicochemical properties of nano-objects is described along with the importance of including sample history and analysis results in a record of provenance information regarding specific batches of nano-objects.

  13. Theoretical modelling of a bi-dimensional U-shaped surface plasmon resonance based fibre optic sensor for sensitivity enhancement

    Energy Technology Data Exchange (ETDEWEB)

    Verma, R K; Gupta, B D [Physics Department, Indian Institute of Technology Delhi, New Delhi-110016 (India)], E-mail: bdgupta@physics.iitd.ernet.in

    2008-05-07

    Theoretical analysis of a surface plasmon resonance based fibre optic sensor with a uniform semi-metal coated U-shaped probe is carried out using a bi-dimensional model. All the rays of the p-polarized light launched in the fibre and their electric vectors are assumed to be confined in the plane of bending of the U-shaped probe. The effect of the bending radius of the probe on the sensitivity of the sensor is studied. The study shows that as the bending radius of the probe decreases the sensitivity of the sensor increases. For the light launching conditions used, the maximum sensitivity achieved is several times more than that reported for a fibre optic tapered probe. In addition to high sensitivity, the most advantageous feature of a U-shaped probe is that it can be used as a point sensor.

  14. Surface sensitivity of four-probe STM resistivity measurements of bulk ZnO correlated to XPS

    Science.gov (United States)

    Lord, Alex M.; Evans, Jonathan E.; Barnett, Chris J.; Allen, Martin W.; Barron, Andrew R.; Wilks, Steve P.

    2017-09-01

    Multi-probe instruments based on scanning tunnelling microscopy (STM) are becoming increasingly common for their ability to perform nano- to atomic-scale investigations of nanostructures, surfaces and in situ reactions. A common configuration is the four-probe STM often coupled with in situ scanning electron microscopy (SEM) that allows precise positioning of the probes onto surfaces and nanostructures enabling electrical and scanning experiments to be performed on highly localised regions of the sample. In this paper, we assess the sensitivity of four-probe STM for in-line resistivity measurements of the bulk ZnO surface. The measurements allow comparisons to established models that are used to relate light plasma treatments (O and H) of the surfaces to the resistivity measurements. The results are correlated to x-ray photoelectron spectroscopy (XPS) and show that four-probe STM can detect changes in surface and bulk conduction mechanisms that are beyond conventional monochromatic XPS.

  15. On the Sensitivity of Atmospheric Model Implied Ocean Heat Transport to the Dominant Terms of the Surface Energy Balance

    Energy Technology Data Exchange (ETDEWEB)

    Gleckler, P J

    2004-11-03

    The oceanic meridional heat transport (T{sub o}) implied by an atmospheric General Circulation Model (GCM) can help evaluate a model's readiness for coupling with an ocean GCM. In this study we examine the T{sub o} from benchmark experiments of the Atmospheric Model Intercomparison Project, and evaluate the sensitivity of T{sub o} to the dominant terms of the surface energy balance. The implied global ocean TO in the Southern Hemisphere of many models is equatorward, contrary to most observationally-based estimates. By constructing a hybrid (model corrected by observations) T{sub o}, an earlier study demonstrated that the implied heat transport is critically sensitive to the simulated shortwave cloud radiative effects, which have been argued to be principally responsible for the Southern Hemisphere problem. Systematic evaluation of one model in a later study suggested that the implied T{sub o} could be equally as sensitive to a model's ocean surface latent heat flux. In this study we revisit the problem with more recent simulations, making use of estimates of ocean surface fluxes to construct two additional hybrid calculations. The results of the present study demonstrate that indeed the implied T{sub o} of an atmospheric model is very sensitive to problems in not only the surface net shortwave, but the latent heat flux as well. Many models underestimate the shortwave radiation reaching the surface in the low latitudes, and overestimate the latent heat flux in the same region. The additional hybrid transport calculations introduced here could become useful model diagnostic tests as estimates of implied ocean surface fluxes are improved.

  16. A 1-D Analytical Model for the Thermally Induced Stresses in the Mould Surface During Die Casting

    DEFF Research Database (Denmark)

    Hattel, Jesper; Hansen, Preben

    1994-01-01

    This paper presents an anlytically based method for predicting the normal stresses in a die mold surface exposed to a thermal load. A example of application of the method is the high-pressure di casting process where the surface stresses in critical cases lead to cracks. Expressions for the normal...

  17. A NEW STRUCTURE AND ITS ANALYTICAL BREAKDOWN MODEL OF HIGH VOLTAGE SOI DEVICE WITH STEP UNMOVABLE SURFACE CHARGES OF BURIED OXIDE LAYER

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A new SOI (Silicon On Insulator) high voltage device with Step Unmovable Surface Charges(SUSC) of buried oxide layer and its analytical breakdown model are proposed in the paper. The unmovable charges are implemented into the upper surface of buried oxide layer to increase the vertical electric field and uniform the lateral one. The 2-D Poisson's equation is solved to demonstrate the modulation effect of the immobile interface charges and analyze the electric field and breakdown voltage with the various geometric parameters and step numbers. A new RESURF (REduce SURface Field) condition of the SOI device considering the interface charges and buried oxide is derived to maximize breakdown voltage. The analytical results are in good agreement with the numerical analysis obtained by the 2-D semiconductor devices simulator MEDICI. As a result, an 1200V breakdown voltage is firstly obtained in 3μm-thick top Si layer, 2μm-thick buried oxide layer and 70μm-length drift region using a linear doping profile of unmovable buried oxide charges.

  18. Analytical solution of second Stokes problem about behaviour of gas over fluctuating surface by means of ellipsoidal statistical equation

    CERN Document Server

    Latyshev, A V

    2012-01-01

    Second Stokes problem about behaviour of rarefied gas filling half-space is analytically solved. A plane limiting half-space makes harmonious fluctuations in the plane. The kinetic equation with modelling integral collisions in form of ellipsoidal statistical model is used . The case of diffusion reflexions of gas molecules from a wall is considered. Function distribution of gas molecules is constructed and mass velocity of gas also in half-space is found. Hydrodynamic character of the solution at small frequencies of fluctuation plane limiting gas is revealed. The force of a friction operating from gas on border making in the plane oscillatory movement is found.

  19. Advanced multiple response surface method of sensitivity analysis for turbine blisk reliability with multi-physics coupling

    Directory of Open Access Journals (Sweden)

    Zhang Chunyi

    2016-08-01

    Full Text Available To reasonably implement the reliability analysis and describe the significance of influencing parameters for the multi-failure modes of turbine blisk, advanced multiple response surface method (AMRSM was proposed for multi-failure mode sensitivity analysis for reliability. The mathematical model of AMRSM was established and the basic principle of multi-failure mode sensitivity analysis for reliability with AMRSM was given. The important parameters of turbine blisk failures are obtained by the multi-failure mode sensitivity analysis of turbine blisk. Through the reliability sensitivity analyses of multiple failure modes (deformation, stress and strain with the proposed method considering fluid–thermal–solid interaction, it is shown that the comprehensive reliability of turbine blisk is 0.9931 when the allowable deformation, stress and strain are 3.7 × 10−3 m, 1.0023 × 109 Pa and 1.05 × 10−2 m/m, respectively; the main impact factors of turbine blisk failure are gas velocity, gas temperature and rotational speed. As demonstrated in the comparison of methods (Monte Carlo (MC method, traditional response surface method (RSM, multiple response surface method (MRSM and AMRSM, the proposed AMRSM improves computational efficiency with acceptable computational accuracy. The efforts of this study provide the AMRSM with high precision and efficiency for multi-failure mode reliability analysis, and offer a useful insight for the reliability optimization design of multi-failure mode structure.

  20. Advanced multiple response surface method of sensitivity analysis for turbine blisk reliability with multi-physics coupling

    Institute of Scientific and Technical Information of China (English)

    Zhang Chunyi; Song Lukai; Fei Chengwei; Lu Cheng; Xie Yongmei

    2016-01-01

    To reasonably implement the reliability analysis and describe the significance of influenc-ing parameters for the multi-failure modes of turbine blisk, advanced multiple response surface method (AMRSM) was proposed for multi-failure mode sensitivity analysis for reliability. The mathematical model of AMRSM was established and the basic principle of multi-failure mode sen-sitivity analysis for reliability with AMRSM was given. The important parameters of turbine blisk failures are obtained by the multi-failure mode sensitivity analysis of turbine blisk. Through the reli-ability sensitivity analyses of multiple failure modes (deformation, stress and strain) with the pro-posed method considering fluid–thermal–solid interaction, it is shown that the comprehensive reliability of turbine blisk is 0.9931 when the allowable deformation, stress and strain are 3.7 × 10-3 m, 1.0023 × 109 Pa and 1.05 × 10-2 m/m, respectively; the main impact factors of tur-bine blisk failure are gas velocity, gas temperature and rotational speed. As demonstrated in the comparison of methods (Monte Carlo (MC) method, traditional response surface method (RSM), multiple response surface method (MRSM) and AMRSM), the proposed AMRSM improves computational efficiency with acceptable computational accuracy. The efforts of this study provide the AMRSM with high precision and efficiency for multi-failure mode reliability analysis, and offer a useful insight for the reliability optimization design of multi-failure mode structure.

  1. Sensitivity experiments on the response of Vb cyclones to sea surface temperature and soil moisture changes

    Science.gov (United States)

    Messmer, Martina; José Gómez-Navarro, Juan; Raible, Christoph C.

    2017-07-01

    Extratropical cyclones of type Vb, which develop over the western Mediterranean and move northeastward, are major natural hazards that are responsible for heavy precipitation over central Europe. To gain further understanding in the governing processes of these Vb cyclones, the study explores the role of soil moisture and sea surface temperature (SST) and their contribution to the atmospheric moisture content. Thereby, recent Vb events identified in the ERA-Interim reanalysis are dynamically downscaled with the Weather Research and Forecasting (WRF) model. Results indicate that a mean high-impact summer Vb event is mostly sensitive to an increase in the Mediterranean SSTs and rather insensitive to Atlantic SSTs and soil moisture changes. Hence, an increase of +5 K in Mediterranean SSTs leads to an average increase of 24 % in precipitation over central Europe. This increase in precipitation is mainly induced by larger mean upward moisture flux over the Mediterranean with increasing Mediterranean SSTs. This further invokes an increase in latent energy release, which leads to an increase in atmospheric instability, i.e. in convective available potential energy. Both the increased availability of atmospheric moisture and the increased instability of the atmosphere, which is able to remove extra moisture from the atmosphere due to convective processes, are responsible for the strong increase in precipitation over the entire region influenced by Vb events. Precipitation patterns further indicate that a strong increase in precipitation is found at the eastern coast of the Adriatic Sea for increased Mediterranean SSTs. This premature loss in atmospheric moisture leads to a significant decrease in atmospheric moisture transport to central Europe and the northeastern flanks of the Alpine mountain chain. This leads to a reduction in precipitation in this high-impact region of the Vb event for an increase in Mediterranean SSTs of +5 K. Furthermore, the intensity of the Vb

  2. Observation of surface reduction of NiO to Ni by surface-sensitive total reflection X-ray spectroscopy using Kramers-Kronig relations

    Science.gov (United States)

    Abe, Hitoshi; Nakayama, Takeshi; Niwa, Yasuhiro; Nitani, Hiroaki; Kondoh, Hiroshi; Nomura, Masaharu

    2016-06-01

    We have developed a promising surface-sensitive X-ray absorption fine structure (XAFS) measurement method. This method is based on total reflection detection and Kramers-Kronig relations, and has been named the KK-XAFS method. Total reflection spectra are transformed via Kramers-Kronig relations to obtain XAFS spectra. KK-XAFS experiments give us surface-sensitive structural parameters, while usual EXAFS analyses yield bulk structural parameters. The total reflection spectra themselves are useful for observing and discussing time evolutions of chemical reactions at surfaces by quick scanning measurements. Chemical species are analyzed to estimate their fractions during reactions. The whole method would be named total reflection X-ray spectroscopy (TREXS). A reduction of the NiO layer at the surface of Ni (30 nm)/Si was observed in a laboratory-built TREXS in situ cell. The method would be applicable to observe chemical reactions starting at surfaces and to study their kinetics and mechanisms.

  3. Sensitivities of surface wave velocities to the medium parameters in a radially anisotropic spherical Earth and inversion strategies

    Directory of Open Access Journals (Sweden)

    Sankar N. Bhattacharya

    2015-11-01

    Full Text Available Sensitivity kernels or partial derivatives of phase velocity (c and group velocity (U with respect to medium parameters are useful to interpret a given set of observed surface wave velocity data. In addition to phase velocities, group velocities are also being observed to find the radial anisotropy of the crust and mantle. However, sensitivities of group velocity for a radially anisotropic Earth have rarely been studied. Here we show sensitivities of group velocity along with those of phase velocity to the medium parameters VSV, VSH , VPV, VPH , h and density in a radially anisotropic spherical Earth. The peak sensitivities for U are generally twice of those for c; thus U is more efficient than c to explore anisotropic nature of the medium. Love waves mainly depends on VSH while Rayleigh waves is nearly independent of VSH . The sensitivities show that there are trade-offs among these parameters during inversion and there is a need to reduce the number of parameters to be evaluated independently. It is suggested to use a nonlinear inversion jointly for Rayleigh and Love waves; in such a nonlinear inversion best solutions are obtained among the model parameters within prescribed limits for each parameter. We first choose VSH, VSV and VPH within their corresponding limits; VPV and h can be evaluated from empirical relations among the parameters. The density has small effect on surface wave velocities and it can be considered from other studies or from empirical relation of density to average P-wave velocity.

  4. Correlation between the Sensitivity to TRAIL and the Expression Level of DR5 on the Surface of Tumor Cells

    Institute of Scientific and Technical Information of China (English)

    Yuanfang Ma; Jun Zhang; Yueping Zhao

    2005-01-01

    OBJECTIVE To investigate the correlation between the sensitivity to the tumor necrosis factor- related apoptosis inducing ligand (TRAIL) and the level of expression of the death receptor 5 (DR5) on the surface of tumor cells.METHODS Anti-DR5 mAbs were used to directly detect the level of expression of DR5 on the surface of tumor cells. Using a TRAIL apoptosis kit and flow cytometry, the sensitivity of the tumor cells to TRAIL-induced apoptosis was determined and the correlation between DR5 expression and sensitivity to TRAIL analyzed.RESULTS The expression level of DR5 on the surface of different tumor cells was as follows: 97.9% in U937 cells, 95.1% in Jurkat cells, 93.8% in SW480 cells, 86.2% in HCT116 cells, 64.2% in HL-60 cells, 46.6% in Hela cells and 13.1% in K562 cells. The TRAIL-induced apoptotic rate was 72.6% in U937 cells, 85.2% in Jurkat cells, 78.6% in SW480 cells, 70.2% in HCT116 cells,60.1% in HL-60 cells, 45.4% in Hela cells and 12.3% in K562 cells. Statistical analysis showed there was a significant positive correlation (r=0.997, P<0.001) between DR5 expression and sensitivity to TRAIL.CONCLUSION The sensitivity of tumor cells to TRAIL is related to the level of expression of DR5 on the surface of tumor cells. These results confirm the importance of DR5 expression for induction of apoptosis by TRAIL.

  5. Development of an analytical methodology for the determination of the antiparasitic drug toltrazuril and its two metabolites in surface water, soil and animal manure

    DEFF Research Database (Denmark)

    Olsen, Jesper; Björklund, Erland; Krogh, Kristine A

    2012-01-01

    This paper presents the development, optimization and validation of a LC-MS/MS methodology to determine the antiparasitic veterinary drug toltrazuril and its two main metabolites, toltrazuril sulfoxide and toltrazuril sulfone, in environmental surface water, soil and animal manure. Using solid...... phase extraction and selective pressurized liquid extraction with integrated clean-up, the analytical method allows for the determination of these compounds down to 0.06-0.13 ng L(-1) in water, 0.01-0.03 ng g(-1)dw in soil and 0.22-0.51 ng g(-1) dw in manure. The deuterated analog of toltrazuril...

  6. Research Note: The sensitivity of surface seismic P-wave data in transversely isotropic media to reflector depth

    KAUST Repository

    Alkhalifah, Tariq Ali

    2016-12-17

    The leading component of the high-frequency asymptotic description of the wavefield, given by the travel time, is governed by the eikonal equation. In anisotropic media, traveltime measurements from seismic experiments conducted along one surface cannot constrain the long-wavelength attribute of the medium along the orthogonal-to-the-surface direction, as anisotropy introduces an independent parameter controlling wave propagation in the orthogonal direction. Since travel times measured on the Earth\\'s surface in transversely isotropic media with a vertical symmetry axis are mainly insensitive to the absolute value of the anisotropic parameter responsible for relating these observations to depth δ, the travel time was perturbed laterally to investigate the traveltime sensitivity to lateral variations in δ. This formulation can be used to develop inversion strategies for lateral variations in δ in acoustic transversely isotropic media, as the surface-recorded data are sensitive to it even if the model is described by the normal moveout velocity and horizontal velocity, or the anellipticity parameter η. Numerical tests demonstrate the enhanced sensitivity of our data when the model is parameterised with a lateral change in δ.

  7. Fast Response and High Sensitivity ZnO/glass Surface Acoustic Wave Humidity Sensors Using Graphene Oxide Sensing Layer

    Science.gov (United States)

    Xuan, Weipeng; He, Mei; Meng, Nan; He, Xingli; Wang, Wenbo; Chen, Jinkai; Shi, Tianjin; Hasan, Tawfique; Xu, Zhen; Xu, Yang; Luo, J. K.

    2014-11-01

    We report ZnO/glass surface acoustic wave (SAW) humidity sensors with high sensitivity and fast response using graphene oxide sensing layer. The frequency shift of the sensors is exponentially correlated to the humidity change, induced mainly by mass loading effect rather than the complex impedance change of the sensing layer. The SAW sensors show high sensitivity at a broad humidity range from 0.5%RH to 85%RH with SAW humidity sensors, complemented with full humidity range measurement, highlights their potential in a wide range of applications.

  8. High-sensitivity time-resolved intracavity laser Fourier transform spectroscopy with vertical cavity surface emitting multiple quantum well lasers

    CERN Document Server

    Picqué, N; Kachanov, A A; Picqu\\'e, Nathalie; Guelachvili, Guy; Kachanov, Alexander A.

    2003-01-01

    Spectra comprised of hundreds of time-components for absorption path lengths up to 130 km have been recorded around 1050 nm by combining two recent techniques, intracavity laser spectroscopy with vertical external cavity surface emitting multiple-quantum-well lasers and time-resolved Fourier transform spectroscopy. A sensitivity of 1 10^{-10} cm^{-1}.Hz^{-1/2} is achieved, for simultaneously acquired 10^4 spectral elements, three orders of magnitude better than the sensitivity obtained in previous similar experiments. Specific advantages of the method, especially for frequency and intensity metrology of weak absorption transitions, are discussed.

  9. Hydrophilic property of 316L stainless steel after treatment by atmospheric pressure corona streamer plasma using surface-sensitive analyses

    Energy Technology Data Exchange (ETDEWEB)

    Al-Hamarneh, Ibrahim, E-mail: hamarnehibrahim@yahoo.com [Department of Physics, Faculty of Science, Al-Balqa Applied University, Salt 19117 (Jordan); Pedrow, Patrick [School of Electrical Engineering and Computer Science, Washington State University, Pullman, WA 99164 (United States); Eskhan, Asma; Abu-Lail, Nehal [Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA 99164 (United States)

    2012-10-15

    Highlights: Black-Right-Pointing-Pointer Surface hydrophilic property of surgical-grade 316L stainless steel was enhanced by Ar-O{sub 2} corona streamer plasma treatment. Black-Right-Pointing-Pointer Hydrophilicity, surface morphology, roughness, and chemical composition before and after plasma treatment were evaluated. Black-Right-Pointing-Pointer Contact angle measurements and surface-sensitive analyses techniques, including XPS and AFM, were carried out. Black-Right-Pointing-Pointer Optimum plasma treatment conditions of the SS 316L surface were determined. - Abstract: Surgical-grade 316L stainless steel (SS 316L) had its surface hydrophilic property enhanced by processing in a corona streamer plasma reactor using O{sub 2} gas mixed with Ar at atmospheric pressure. Reactor excitation was 60 Hz ac high-voltage (0-10 kV{sub RMS}) applied to a multi-needle-to-grounded screen electrode configuration. The treated surface was characterized with a contact angle tester. Surface free energy (SFE) for the treated stainless steel increased measurably compared to the untreated surface. The Ar-O{sub 2} plasma was more effective in enhancing the SFE than Ar-only plasma. Optimum conditions for the plasma treatment system used in this study were obtained. X-ray photoelectron spectroscopy (XPS) characterization of the chemical composition of the treated surfaces confirms the existence of new oxygen-containing functional groups contributing to the change in the hydrophilic nature of the surface. These new functional groups were generated by surface reactions caused by reactive oxidation of substrate species. Atomic force microscopy (AFM) images were generated to investigate morphological and roughness changes on the plasma treated surfaces. The aging effect in air after treatment was also studied.

  10. A self-amplified transistor immunosensor under dual gate operation: highly sensitive detection of hepatitis B surface antigen

    Science.gov (United States)

    Lee, I.-K.; Jeun, M.; Jang, H.-J.; Cho, W.-J.; Lee, K. H.

    2015-10-01

    Ion-sensitive field-effect transistors (ISFETs), although they have attracted considerable attention as effective immunosensors, have still not been adopted for practical applications owing to several problems: (1) the poor sensitivity caused by the short Debye screening length in media with high ion concentration, (2) time-consuming preconditioning processes for achieving the highly-diluted media, and (3) the low durability caused by undesirable ions such as sodium chloride in the media. Here, we propose a highly sensitive immunosensor based on a self-amplified transistor under dual gate operation (immuno-DG ISFET) for the detection of hepatitis B surface antigen. To address the challenges in current ISFET-based immunosensors, we have enhanced the sensitivity of an immunosensor by precisely tailoring the nanostructure of the transistor. In the pH sensing test, the immuno-DG ISFET showed superior sensitivity (2085.53 mV per pH) to both standard ISFET under single gate operation (58.88 mV per pH) and DG ISFET with a non-tailored transistor (381.14 mV per pH). Moreover, concerning the detection of hepatitis B surface antigens (HBsAg) using the immuno-DG ISFET, we have successfully detected trace amounts of HBsAg (22.5 fg mL-1) in a non-diluted 1× PBS medium with a high sensitivity of 690 mV. Our results demonstrate that the proposed immuno-DG ISFET can be a biosensor platform for practical use in the diagnosis of various diseases.Ion-sensitive field-effect transistors (ISFETs), although they have attracted considerable attention as effective immunosensors, have still not been adopted for practical applications owing to several problems: (1) the poor sensitivity caused by the short Debye screening length in media with high ion concentration, (2) time-consuming preconditioning processes for achieving the highly-diluted media, and (3) the low durability caused by undesirable ions such as sodium chloride in the media. Here, we propose a highly sensitive immunosensor

  11. Enhanced Sensitive Love Wave Surface Acoustic Wave Sensor Designed for Immunoassay Formats

    OpenAIRE

    Mihaela Puiu; Ana-Maria Gurban; Lucian Rotariu; Simona Brajnicov; Cristian Viespe; Camelia Bala

    2015-01-01

    We report a Love wave surface acoustic wave (LW-SAW) immunosensor designed for the detection of high molecular weight targets in liquid samples, amenable also for low molecular targets in surface competition assays. We implemented a label-free interaction protocol similar to other surface plasmon resonance bioassays having the advantage of requiring reduced time analysis. The fabricated LW-SAW sensor supports the detection of the target in the nanomolar range, and can be ultimately incorporat...

  12. Au-Ag-Au double shell nanoparticles-based localized surface plasmon resonance and surface-enhanced Raman scattering biosensor for sensitive detection of 2-mercapto-1-methylimidazole.

    Science.gov (United States)

    Liao, Xue; Chen, Yanhua; Qin, Meihong; Chen, Yang; Yang, Lei; Zhang, Hanqi; Tian, Yuan

    2013-12-15

    In this paper, Au-Ag-Au double shell nanoparticles were prepared based on the reduction of the metal salts HAuCl4 and AgNO3 at the surface of seed particles. Due to the synergistic effect between Au and Ag, the hybrid nanoparticles are particularly stable and show excellent performances on the detection of 2-mercapto-1-methylimidazole (methimazole). The binding of target molecule at the surface of Au-Ag-Au double shell nanoparticles was demonstrated based on both localized surface plasmon resonance (LSPR) and surface-enhanced Raman scattering (SERS) spectra. The LSPR intensity is directly proportional to the methimazole concentration in the range of 0.10-3.00×10(-7) mol L(-1). The SERS spectrum can be applied in identification of methimazole molecule. The LSPR coupled with SERS based on the Au-Ag-Au double shell nanoparticles would be very attractive for the quantitative determination and qualitative analysis of the analytes in medicines.

  13. Temperature accelerated Monte Carlo (TAMC): a method for sampling the free energy surface of non-analytical collective variables.

    Science.gov (United States)

    Ciccotti, Giovanni; Meloni, Simone

    2011-04-07

    We introduce a new method to simulate the physics of rare events. The method, an extension of the Temperature Accelerated Molecular Dynamics, comes in use when the collective variables introduced to characterize the rare events are either non-analytical or so complex that computing their derivative is not practical. We illustrate the functioning of the method by studying the homogeneous crystallization in a sample of Lennard-Jones particles. The process is studied by introducing a new collective variable that we call Effective Nucleus Size N. We have computed the free energy barriers and the size of critical nucleus, which result in agreement with data available in the literature. We have also performed simulations in the liquid domain of the phase diagram. We found a free energy curve monotonically growing with the nucleus size, consistent with the liquid domain.

  14. Analytic Approximate Solutions for MHD Boundary-Layer Viscoelastic Fluid Flow over Continuously Moving Stretching Surface by Homotopy Analysis Method with Two Auxiliary Parameters

    Directory of Open Access Journals (Sweden)

    M. M. Rashidi

    2012-01-01

    Full Text Available In this study, a steady, incompressible, and laminar-free convective flow of a two-dimensional electrically conducting viscoelastic fluid over a moving stretching surface through a porous medium is considered. The boundary-layer equations are derived by considering Boussinesq and boundary-layer approximations. The nonlinear ordinary differential equations for the momentum and energy equations are obtained and solved analytically by using homotopy analysis method (HAM with two auxiliary parameters for two classes of visco-elastic fluid (Walters’ liquid B and second-grade fluid. It is clear that by the use of second auxiliary parameter, the straight line region in ℏ-curve increases and the convergence accelerates. This research is performed by considering two different boundary conditions: (a prescribed surface temperature (PST and (b prescribed heat flux (PHF. The effect of involved parameters on velocity and temperature is investigated.

  15. Sensitivity of land surface modeling to parameters: An uncertainty quantification method applied to the Community Land Model

    Science.gov (United States)

    Ricciuto, D. M.; Mei, R.; Mao, J.; Hoffman, F. M.; Kumar, J.

    2015-12-01

    Uncertainties in land parameters could have important impacts on simulated water and energy fluxes and land surface states, which will consequently affect atmospheric and biogeochemical processes. Therefore, quantification of such parameter uncertainties using a land surface model is the first step towards better understanding of predictive uncertainty in Earth system models. In this study, we applied a random-sampling, high-dimensional model representation (RS-HDMR) method to analyze the sensitivity of simulated photosynthesis, surface energy fluxes and surface hydrological components to selected land parameters in version 4.5 of the Community Land Model (CLM4.5). Because of the large computational expense of conducting ensembles of global gridded model simulations, we used the results of a previous cluster analysis to select one thousand representative land grid cells for simulation. Plant functional type (PFT)-specific uniform prior ranges for land parameters were determined using expert opinion and literature survey, and samples were generated with a quasi-Monte Carlo approach-Sobol sequence. Preliminary analysis of 1024 simulations suggested that four PFT-dependent parameters (including slope of the conductance-photosynthesis relationship, specific leaf area at canopy top, leaf C:N ratio and fraction of leaf N in RuBisco) are the dominant sensitive parameters for photosynthesis, surface energy and water fluxes across most PFTs, but with varying importance rankings. On the other hand, for surface ans sub-surface runoff, PFT-independent parameters, such as the depth-dependent decay factors for runoff, play more important roles than the previous four PFT-dependent parameters. Further analysis by conditioning the results on different seasons and years are being conducted to provide guidance on how climate variability and change might affect such sensitivity. This is the first step toward coupled simulations including biogeochemical processes, atmospheric processes

  16. High-sensitivity label-free optical fiber optrodes based on the excitation of Bloch surface waves

    Science.gov (United States)

    Scaravilli, M.; Castaldi, G.; Cusano, A.; Galdi, V.

    2016-05-01

    In this study, the possibility to excite Bloch surface waves (BSWs) on the tip of a single-mode optical fiber is explored for the first time. In particular, we first show the possibility to achieve an on-tip excitation of BSWs, with optimized characteristic of the arising resonances, via an "all-fiber" grating-coupled configuration. Furthermore, envisioning novel high-performance fiber tip nanoprobes for label-free biosensing, we introduce an ad hoc design aimed at maximizing the refractive-index sensitivity. Numerical results indicate that the estimated sensitivities are comparable with those exhibited by current plasmonic lab-on-tip bio-probes, but are accompanied by a higher spectral selectivity. Therefore, this preliminary work paves the way to the development of new classes of miniaturized surface-wave optical fiber devices for low-detection-limit label-free chemical and biological sensing.

  17. Polydopamine-based surface modification of mesoporous silica nanoparticles as pH-sensitive drug delivery vehicles for cancer therapy.

    Science.gov (United States)

    Chang, Danfeng; Gao, Yongfeng; Wang, Lijun; Liu, Gan; Chen, Yuhan; Wang, Teng; Tao, Wei; Mei, Lin; Huang, Laiqiang; Zeng, Xiaowei

    2016-02-01

    A novel pH-sensitive drug delivery system of mesoporous silica nanoparticles (MSNs) which were modified by polydopamine (PDA) for controlled release of cationic amphiphilic drug desipramine (DES) was prepared. MSNs-DES-PDA were characterized in terms of size, size distribution, surface morphology, BET surface area, mesoporous size and pore volume, drug loading content and in vitro drug release profile. MSNs-DES-PDA had high drug loading content and pH sensitivity. The DES release profiles of MSNs-DES and MSNs-DES-PDA were totally different, and the drug release of MSNs-DES-PDA accelerated with increasing acidity. MSNs-DES-PDA can be internalized into cells. In vitro experiments demonstrated that MSNs-DES-PDA had higher cytotoxicity and inhibitory effects on acid sphingomyelinase than those of free DES. This drug delivery system was beneficial for controlled release and cancer therapy.

  18. Engineering and Characterization of Peptides and Proteins at Surfaces and Interfaces: A Case Study in Surface-Sensitive Vibrational Spectroscopy.

    Science.gov (United States)

    Ding, Bei; Jasensky, Joshua; Li, Yaoxin; Chen, Zhan

    2016-06-21

    Understanding molecular structures of interfacial peptides and proteins impacts many research fields by guiding the advancement of biocompatible materials, new and improved marine antifouling coatings, ultrasensitive and highly specific biosensors and biochips, therapies for diseases related to protein amyloid formation, and knowledge on mechanisms for various membrane proteins and their interactions with ligands. Developing methods for measuring such unique systems, as well as elucidating the structure and function relationship of such biomolecules, has been the goal of our lab at the University of Michigan. We have made substantial progress to develop sum frequency generation (SFG) vibrational spectroscopy into a powerful technique to study interfacial peptides and proteins, which lays a foundation to obtain unique and valuable insights when using SFG to probe various biologically relevant systems at the solid/liquid interface in situ in real time. One highlighting feature of this Account is the demonstration of the power of combining SFG with other techniques and methods such as ATR-FTIR, surface engineering, MD simulation, liquid crystal sensing, and isotope labeling in order to study peptides and proteins at interfaces. It is necessary to emphasize that SFG plays a major role in these studies, while other techniques and methods are supplemental. The central role of SFG is to provide critical information on interfacial peptide and protein structure (e.g., conformation and orientation) in order to elucidate how surface engineering (e.g., to vary the structure) can ultimately affect surface function (e.g., to optimize the activity). This Account focuses on the most significant recent progress in research on interfacial peptides and proteins carried out by our group including (1) the development of SFG analysis methods to determine orientations of regular as well as disrupted secondary structures, and the successful demonstration and application of an isotope

  19. Influence of surface states of CuInS2 quantum dots in quantum dots sensitized photo-electrodes

    Science.gov (United States)

    Peng, Zhuoyin; Liu, Yueli; Wu, Lei; Zhao, Yinghan; Chen, Keqiang; Chen, Wen

    2016-12-01

    Surface states are significant factor for the enhancement of electrochemical performance in CuInS2 quantum dot sensitized photo-electrodes. DDT, OLA, MPA, and S2- ligand capped CuInS2 quantum dot sensitized photo-electrodes are prepared by thermolysis, solvethermal and ligand-exchange processes, respectively, and their optical properties and photoelectrochemical properties are investigated. The S2- ligand enhances the UV-vis absorption and electron-hole separation property as well as the excellent charge transfer performance of the photo-electrodes, which is attributed to the fact that the atomic S2- ligand for the interfacial region of quantum dots may improve the electron transfer rate. These S2--capped CuInS2 quantum dot sensitized photo-electrodes exhibit the excellent photoelectrochemical efficiency and IPCE peak value, which is higher than that of the samples with DDT, OLA and MPA ligands.

  20. Fabrication and characterization of gold nanocrown arrays on a gold film for a high-sensitivity surface plasmon resonance biosensor

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Munsik; Kim, Nak-hyeon; Eom, Seyoung [Department of Biomedical Engineering, Kyung Hee University, Yongin 446-701 (Korea, Republic of); Kim, Tae Woo [School of East–West Medical Science, Kyung Hee University, Yongin 446-701 (Korea, Republic of); Byun, Kyung Min, E-mail: kmbyun@khu.ac.kr [Department of Biomedical Engineering, Kyung Hee University, Yongin 446-701 (Korea, Republic of); Park, Hyeong-Ho, E-mail: hyeongho.park@kanc.re.kr [Nano Process Division, Korea Advanced Nano Fab Center, Suwon 443-270 (Korea, Republic of)

    2015-07-31

    We report on a versatile method to fabricate gold nanocrown arrays on a thin gold film based on ultraviolet nanoimprint lithography and tilted evaporation technique. We realize highly ordered 2-dimensional nanocrown arrays and characterize their sizes and morphologies using scanning electron microscopy. To demonstrate an enhanced surface plasmon resonance (SPR) detection by the fabricated gold nanocrown samples, biosensing experiments are performed by measuring SPR angle shift for biotin–streptavidin interaction and bulk refractive index change of dielectric medium. We hope that the suggested plasmonic platform with a high sensitivity could be extended to a variety of biomolecular binding reactions. - Highlights: • Gold nanocrown arrays are produced by nanoimprint lithography and tilted evaporation. • Use of gold nanocrown arrays can improve the sensor sensitivity significantly. • Improved sensitivity is due to enhanced field–matter interaction at gold nanocrowns.

  1. Molecularly Imprinted Polymer (MIP) Film with Improved Surface Area Developed by Using Metal-Organic Framework (MOF) for Sensitive Lipocalin (NGAL) Determination.

    Science.gov (United States)

    Iskierko, Zofia; Sharma, Piyush Sindhu; Prochowicz, Daniel; Fronc, Krzysztof; D'Souza, Francis; Toczydłowska, Diana; Stefaniak, Filip; Noworyta, Krzysztof

    2016-08-10

    Electropolymerizable functional and cross-linking monomers were used to prepare conducting molecularly imprinted polymer film with improved surface area with the help of a sacrificial metal-organic framework (MOF). Subsequent dissolution of the MOF layer resulted in a surface developed MIP film. This surface enlargement increased the analyte accessibility to imprinted molecular cavities. Application of the porous MIP film as a recognition unit of an extended-gate field effect transistor (EG-FET) chemosensor effectively enhanced analytical current signals of determination of recombinant human neutrophil gelatinase-associated lipocalin (NGAL).

  2. Two-dimensional semi-analytical model of subthreshold surface potential and drain current for double-doping polysilicon gate MOSFET

    Science.gov (United States)

    Xu, Hui-Fang; Dai, Yue-Hua; Xu, Jian-Bin; Li, Ning; Yang, Jin; Zheng, Chang-Yong

    2015-05-01

    A semi-analytical subthreshold surface potential model for double-doping polysilicon gate (DDPG) MOSFETs is presented. By introducing two rectangular sources located in the gate insulator and the channel-depleted region, the two-dimensional (2D) Poisson equations are solved using a semi-analytical method combined with an eigenfunction expansion method. Expressions for the potentials are obtained as special functions of infinite series expressions. A subthreshold drain current is proposed on the basis of the potential profile, and it accounts for the carriers’ drift diffusion and thermionic emission theory. The advantage of this work is that the two-dimensional treatment of the gate insulator region has resulted in physical consistency across a dielectric boundary. The proposed model not only offers physical insight into device physics but also provides the basic designing guideline for DDPG MOSFETs, enabling the designer to optimize the device in accordance with the application. Very good agreement for both the subthreshold surface potential and drain current is observed between the model calculations and the simulated results.

  3. Surface sensitivity effects with local probe scanning Auger–scanning electron microscopy

    NARCIS (Netherlands)

    Agterveld, D.T.L. van; Palasantzas, G.; Hosson, J.Th.M. De

    1999-01-01

    This letter concentrates on a quantitative description of surface roughness effects on Auger peak-line profiles for pure and alloyed specimens. The nanometer lateral electron probe size of the order of 10 nm yielded peak-line profiles that capture surface topology variations down to nanometer-length

  4. Rational Design of a Chalcogenopyrylium-Based Surface-Enhanced Resonance Raman Scattering-Nanoprobe with Attomolar Sensitivity

    Science.gov (United States)

    Wall, Matthew A.; Huang, Ruimin; Detty, Michael R.; Kircher, Moritz F.

    2015-01-01

    High sensitivity and specificity are two desirable features in biomedical imaging. Raman imaging has surfaced as a promising optical modality that offers both. Here, we report the design and synthesis of a group of near infrared absorbing 2-thienyl-substituted chalcogenopyrylium dyes tailored to have high affinity for gold. When adsorbed onto gold nanoparticles, these dyes produce biocompatible SERRS-nanoprobes with attomolar limits of detection amenable to ultrasensitive in vivo multiplexed tumor and disease marker detection. PMID:25800697

  5. Rational design of a chalcogenopyrylium-based surface-enhanced resonance Raman scattering nanoprobe with attomolar sensitivity

    Science.gov (United States)

    Harmsen, Stefan; Bedics, Matthew A.; Wall, Matthew A.; Huang, Ruimin; Detty, Michael R.; Kircher, Moritz F.

    2015-03-01

    High sensitivity and specificity are two desirable features in biomedical imaging. Raman imaging has surfaced as a promising optical modality that offers both. Here we report the design and synthesis of a group of near-infrared absorbing 2-thienyl-substituted chalcogenopyrylium dyes tailored to have high affinity for gold. When adsorbed onto gold nanoparticles, these dyes produce biocompatible SERRS nanoprobes with attomolar limits of detection amenable to ultrasensitive in vivo multiplexed tumour and disease marker detection.

  6. Sensitivity of Land Surface Parameters on Thunderstorm Simulation through HRLDAS-WRF Coupling Mode

    Science.gov (United States)

    Kumar, Dinesh; Kumar, Krishan; Mohanty, U. C.; Kisore Osuri, Krishna

    2016-07-01

    Land surface characteristics play an important role in large scale, regional and mesoscale atmospheric process. Representation of land surface characteristics can be improved through coupling of mesoscale atmospheric models with land surface models. Mesoscale atmospheric models depend on Land Surface Models (LSM) to provide land surface variables such as fluxes of heat, moisture, and momentum for lower boundary layer evolution. Studies have shown that land surface properties such as soil moisture, soil temperature, soil roughness, vegetation cover, have considerable effect on lower boundary layer. Although, the necessity to initialize soil moisture accurately in NWP models is widely acknowledged, monitoring soil moisture at regional and global scale is a very tough task due to high spatial and temporal variability. As a result, the available observation network is unable to provide the required spatial and temporal data for the most part of the globe. Therefore, model for land surface initializations rely on updated land surface properties from LSM. The solution for NWP land-state initialization can be found by combining data assimilation techniques, satellite-derived soil data, and land surface models. Further, it requires an intermediate step to use observed rainfall, satellite derived surface insolation, and meteorological analyses to run an uncoupled (offline) integration of LSM, so that the evolution of modeled soil moisture can be forced by observed forcing conditions. Therefore, for accurate land-state initialization, high resolution land data assimilation system (HRLDAS) is used to provide the essential land surface parameters. Offline-coupling of HRLDAS-WRF has shown much improved results over Delhi, India for four thunder storm events. The evolution of land surface variables particularly soil moisture, soil temperature and surface fluxes have provided more realistic condition. Results have shown that most of domain part became wetter and warmer after

  7. A self-amplified transistor immunosensor under dual gate operation: highly sensitive detection of hepatitis B surface antigen.

    Science.gov (United States)

    Lee, I-K; Jeun, M; Jang, H-J; Cho, W-J; Lee, K H

    2015-10-28

    Ion-sensitive field-effect transistors (ISFETs), although they have attracted considerable attention as effective immunosensors, have still not been adopted for practical applications owing to several problems: (1) the poor sensitivity caused by the short Debye screening length in media with high ion concentration, (2) time-consuming preconditioning processes for achieving the highly-diluted media, and (3) the low durability caused by undesirable ions such as sodium chloride in the media. Here, we propose a highly sensitive immunosensor based on a self-amplified transistor under dual gate operation (immuno-DG ISFET) for the detection of hepatitis B surface antigen. To address the challenges in current ISFET-based immunosensors, we have enhanced the sensitivity of an immunosensor by precisely tailoring the nanostructure of the transistor. In the pH sensing test, the immuno-DG ISFET showed superior sensitivity (2085.53 mV per pH) to both standard ISFET under single gate operation (58.88 mV per pH) and DG ISFET with a non-tailored transistor (381.14 mV per pH). Moreover, concerning the detection of hepatitis B surface antigens (HBsAg) using the immuno-DG ISFET, we have successfully detected trace amounts of HBsAg (22.5 fg mL(-1)) in a non-diluted 1× PBS medium with a high sensitivity of 690 mV. Our results demonstrate that the proposed immuno-DG ISFET can be a biosensor platform for practical use in the diagnosis of various diseases.

  8. The sensitivity of biological finite element models to the resolution of surface geometry: a case study of crocodilian crania

    Directory of Open Access Journals (Sweden)

    Matthew R. McCurry

    2015-06-01

    Full Text Available The reliability of finite element analysis (FEA in biomechanical investigations depends upon understanding the influence of model assumptions. In producing finite element models, surface mesh resolution is influenced by the resolution of input geometry, and influences the resolution of the ensuing solid mesh used for numerical analysis. Despite a large number of studies incorporating sensitivity studies of the effects of solid mesh resolution there has not yet been any investigation into the effect of surface mesh resolution upon results in a comparative context. Here we use a dataset of crocodile crania to examine the effects of surface resolution on FEA results in a comparative context. Seven high-resolution surface meshes were each down-sampled to varying degrees while keeping the resulting number of solid elements constant. These models were then subjected to bite and shake load cases using finite element analysis. The results show that incremental decreases in surface resolution can result in fluctuations in strain magnitudes, but that it is possible to obtain stable results using lower resolution surface in a comparative FEA study. As surface mesh resolution links input geometry with the resulting solid mesh, the implication of these results is that low resolution input geometry and solid meshes may provide valid results in a comparative context.

  9. Analytic model of the effect of poly-Gaussian roughness on rarefied gas flow near the surface

    Science.gov (United States)

    Aksenova, Olga A.; Khalidov, Iskander A.

    2016-11-01

    The dependence of the macro-parameters of the flow on surface roughness of the walls and on geometrical shape of the surface is investigated asymptotically and numerically in a rarefied gas molecular flow at high Knudsen numbers. Surface roughness is approximated in statistical simulation by the model of poly-Gaussian (with probability density as the mixture of Gaussian densities [1]) random process. Substantial difference is detected for considered models of the roughness (Gaussian, poly-Gaussian and simple models applied by other researchers), as well in asymptotical expressions [3], as in numerical results. For instance, the influence of surface roughness on momentum and energy exchange coefficients increases noticeably for poly-Gaussian model compared to Gaussian one (although the main properties of poly-Gaussian random processes and fields are similar to corresponding properties of Gaussian processes and fields). Main advantage of the model is based on relative simple relations between the parameters of the model and the basic statistical characteristics of random field. Considered statistical approach permits to apply not only diffuse-specular model of the local scattering function V0 of reflected gas atoms, but also Cercignani-Lampis scattering kernel or phenomenological models of scattering function. Thus, the comparison between poly-Gaussian and Gaussian models shows more significant effect of roughness in aerodynamic values for poly-Gaussian model.

  10. Mass sensitivity of layered shear-horizontal surface acoustic wave devices for sensing applications

    Science.gov (United States)

    Kalantar-Zadeh, Kourosh; Trinchi, Adrian; Wlodarski, Wojtek; Holland, Anthony; Galatsis, Kosmas

    2001-11-01

    Layered Surface Acoustic Wave (SAW) devices that allow the propagation of Love mode acoustic waves will be studied in this paper. In these devices, the substrate allows the propagation of Surface Skimming Bulks Waves (SSBWs). By depositing layers, that the speed of Shear Horizontal (SH) acoustic wave propagation is less than that of the substrate, the propagation mode transforms to Love mode. Love mode devices which will be studied in this paper, have SiO2 and ZnO acoustic guiding layers. As Love mode of propagation has no movement of particles component normal to the active sensor surface, they can be employed for the sensing applications in the liquid media.

  11. Enhanced Sensitive Love Wave Surface Acoustic Wave Sensor Designed for Immunoassay Formats

    Directory of Open Access Journals (Sweden)

    Mihaela Puiu

    2015-05-01

    Full Text Available We report a Love wave surface acoustic wave (LW-SAW immunosensor designed for the detection of high molecular weight targets in liquid samples, amenable also for low molecular targets in surface competition assays. We implemented a label-free interaction protocol similar to other surface plasmon resonance bioassays having the advantage of requiring reduced time analysis. The fabricated LW-SAW sensor supports the detection of the target in the nanomolar range, and can be ultimately incorporated in portable devices, suitable for point-of-care testing (POCT applications.

  12. Enhanced sensitive love wave surface acoustic wave sensor designed for immunoassay formats.

    Science.gov (United States)

    Puiu, Mihaela; Gurban, Ana-Maria; Rotariu, Lucian; Brajnicov, Simona; Viespe, Cristian; Bala, Camelia

    2015-05-05

    We report a Love wave surface acoustic wave (LW-SAW) immunosensor designed for the detection of high molecular weight targets in liquid samples, amenable also for low molecular targets in surface competition assays. We implemented a label-free interaction protocol similar to other surface plasmon resonance bioassays having the advantage of requiring reduced time analysis. The fabricated LW-SAW sensor supports the detection of the target in the nanomolar range, and can be ultimately incorporated in portable devices, suitable for point-of-care testing (POCT) applications.

  13. Improvement of the sensitivity of the surface plasmon resonance sensors based on multi-layer modulation techniques

    Science.gov (United States)

    Zhao, Xihong; Chu-Su, Yu; Tsai, Woo-Hu; Wang, Ching-Ho; Chuang, Tsung-Liang; Lin, Chii-Wann; Tsao, Yu-Chia; Wu, Mu-Shiang

    2015-01-01

    In this study, a multi-layer modulation technique was used in an SPR optical fiber sensor to enhance the sensitivity of the SPR optical fiber sensor by adjusting the SPR resonant wavelength. The sputtering process deposited 20 nm of TiO2, 11 nm of SiO2 and 30 nm of gold film on the material surface to change the refractive index. Regardless of the different refractive index solutions (1.32 and 1.36), the sensitivities in wavelength interrogation of the SPR optical fiber with the single gold thin film and multi-layers modulation were 1.08×10-5 RIUs and 1.74×10-6 RIUs, respectively. The results showed the significant differences between the different refractive index solutions of 1.32 and 1.36 using the 850 nm light source to analyze the SPR optical fiber sensor in real-time. The sensitivities in intensity interrogation of the SPR optical fiber with the single gold thin film and multi-layers modulation were 1.08×10-3 RIUs and 1.73×10-4 RIUs, respectively, which indicated that the multi-layer modulation techniques could enhance the sensitivity of the SPR optical fiber sensor. The compact size of the multi-layer SPR fiber sensor had a wider detecting range of the refractive index and higher sensitivity, which had the potential for other applications in biological analysis with suitable wavelength.

  14. Increasing the Sensitivity of Surface Acoustic Wave (SAW) Chemical Sensors and other Chemical Sensing Investigations

    Science.gov (United States)

    2010-03-01

    that composes the wire. Nanowires sensitive to methanol and ethanol are composed of Polypyrrole (PPy) and Polyaniline ( PANI ). Palladium (Pd) nanowires...nanowires involves measuring the v resistance of palladium, polypyrrole and polyaniline nanowires. The nanowires need to be measured with currents of

  15. The sensitivity of regional transpiration to land-surface characteristics: significance of feedback.

    NARCIS (Netherlands)

    Jacobs, C.M.J.; Bruin, de H.A.R.

    1992-01-01

    Several authors have determined the sensitivity of transpiration to different environmental parameters using the Penman-Monteith equation. In their studies the interaction between transpiration and, for example, the humidity of the air is ignored: the feedback with the planetary boundary layer (PBL)

  16. Chemically sensitive surface plasmon devices employing a self-assembled monolayer composite film

    Science.gov (United States)

    DePriest, J. C.; Meriaudeau, Fabrice; Oden, Patrick I.; Downey, Todd R.; Passian, A.; Wig, A. G.; Ferrell, Trinidad L.

    1998-12-01

    In this paper the results of detecting volatile organic compounds (VOC) employing surface plasmon-based sensors are presented. The initial step in preparing the sensing elements herein requires depositing Au degree(s) on a quartz slide. The sensing elements are based on either (1) freshly deposited Au degree(s) or (2) growth of a self assembled monolayer composite film (SAM) on to a freshly deposited Au degree(s) surface. The desired SAM is either (1) acid terminated using (omega) -mercaptoundecanoic acid (MUA-COOH) or (2) Cu2+ metal ion terminated yielding (omega) - mercaptoundecanoic acid-Cu2+ (MUA-Cu2+). The experimental apparatus shown here measures the reflectivity of the Au degree(s) surface as a function of time at a given angle. The response of this surface plasmon device to various VOC's is correlated to the composition of the SAM film.

  17. Surface treatment properties of CdS quantum dot-sensitized solar cells

    National Research Council Canada - National Science Library

    Razzaq, Abdul; Lee, Jun Young; Bhattacharya, Bhaskar; Park, Jung-Ki

    2014-01-01

    .... Present work describes a simple, modified in situ route designed by mimicking the adsorption principle of dyes in DSSCs for surface modification and linking of CdS-Quantum Dots (QDs) to TiO2 electrode...

  18. In Situ Measurement of Airway Surface Liquid [K+] Using a Ratioable K+-sensitive Fluorescent Dye*

    OpenAIRE

    Namkung, Wan; Song, Yuanlin; Mills, Aaron D.; Padmawar, Prashant; Finkbeiner, Walter E.; Verkman, A. S.

    2009-01-01

    The airway surface liquid (ASL) is the thin fluid layer lining airway surface epithelial cells, whose volume and composition are tightly regulated and may be abnormal in cystic fibrosis (CF). We synthesized a two-color fluorescent dextran to measure ASL [K+], TAC-Lime-dextran-TMR, consisting of a green-fluorescing triazacryptand K+ ionophore-Bodipy conjugate, coupled to dextran, together with a red fluorescing tetramethylrhodamine reference chromophore. TAC-Lime-dextran-TMR fluorescence was K...

  19. Decay of isolated surface features driven by the Gibbs-Thomson effect in analytic model and simulation

    OpenAIRE

    McLean, James G.; Krishnamachari, B.; Peale, D. R.; Chason, E.; Sethna, James P.; Cooper, B. H.

    1996-01-01

    A theory based on the thermodynamic Gibbs-Thomson relation is presented which provides the framework for understanding the time evolution of isolated nanoscale features (i.e., islands and pits) on surfaces. Two limiting cases are predicted, in which either diffusion or interface transfer is the limiting process. These cases correspond to similar regimes considered in previous works addressing the Ostwald ripening of ensembles of features. A third possible limiting case is noted for the specia...

  20. Study on the turbulence model sensitivity for various cross-corrugated surfaces applied to matrix type heat exchanger

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jun Myung; Ha, Man Yeong; Son, Chang Min; Doo, Jeong Hoon; Min, June Kee [Pusan National University, Busan (Korea, Republic of)

    2016-03-15

    Diverse cross-corrugated surface geometries were considered to estimate the sensitivity of four variants of k-ε turbulence models (Low Reynolds, standard, RNG and realizable models). The cross-corrugated surfaces considered in this study are a conventional sinusoidal shape and two different asymmetric shapes. The numerical simulations using the steady incompressible Reynolds-averaged Navier Stokes (RANS) equations were carried out to obtain the steady solutions of the flow and thermal fields in the unitary cell of the heat exchanger matrix. In addition, the experimental test for the measurement of local convective heat transfer coefficients on the heat transfer surfaces was performed by means of the Transient liquid crystal (TLC) technique in order to compare the numerical results with the measured data. The features on detailed flow structure and corresponding heat transfer in the unitary cell of the matrix type heat exchanger are compared and analyzed against four different turbulence models considered in this study.

  1. Ancient mercury-based plating methods: combined use of surface analytical techniques for the study of manufacturing process and degradation phenomena.

    Science.gov (United States)

    Ingo, Gabriel Maria; Guida, Giuseppe; Angelini, Emma; Di Carlo, Gabriella; Mezzi, Alessio; Padeletti, Giuseppina

    2013-11-19

    Fire gilding and silvering are age-old mercury-based processes used to coat thesurface of less precious substrates with thin layers of gold or silver. In ancient times, these methods were used to produce and decorate different types of artefacts, such as jewels, statues, amulets, and commonly-used objects. Gilders performed these processes not only to decorate objects but also to simulate the appearance of gold or silver, sometimes fraudulently. From a technological point of view, the aim of these workmen over 2000 years ago was to make the precious metal coatings as thin and adherent as possible. This was in order to save expensive metals and to improve the resistance to the wear caused by continued use and circulation. Without knowledge about the chemical-physical processes, the ancient crafts-men systematically manipulated these metals to create functional and decorative artistic objects. The mercury-based methods were also fraudulently used in ancient times to produce objects such as jewels and coins that looked like they were made of silver or gold but actually had a less precious core. These coins were minted by counterfeiters but also by the official issuing authorities. The latter was probably because of a lack of precious metals, reflecting periods of severe economic conditions. In this Account, we discuss some representative cases of gold- and silver-coatedobjects, focusing on unique and valuable Roman and Dark Ages period works of art, such as the St. Ambrogio's altar (825 AD), and commonly used objects. We carried out the investigations using surface analytical methods, such as selected area X-ray photoelectron spectroscopy and scanning electron microscopy combined with energy-dispersive spectroscopy. We used these methods to investigate the surface and subsurface chemical features of these important examples of art and technology, interpreting some aspects of the manufacturing methods and of disclosing degradation agents and mechanisms. These findings

  2. Sensitivity of the Mediterranean sea level to atmospheric pressure and free surface elevation numerical formulation in NEMO

    Directory of Open Access Journals (Sweden)

    P. Oddo

    2014-06-01

    Full Text Available The sensitivity of the dynamics of the Mediterranean Sea to atmospheric pressure and free surface elevation formulation using NEMO (Nucleus for European Modelling of the Ocean was evaluated. Four different experiments were carried out in the Mediterranean Sea using filtered or explicit free surface numerical schemes and accounting for the effect of atmospheric pressure in addition to wind and buoyancy fluxes. Model results were evaluated by coherency and power spectrum analysis with tide gauge data. We found that atmospheric pressure plays an important role for periods shorter than 100 days. The free surface formulation is important to obtain the correct ocean response for periods shorter than 30 days. At frequencies higher than 15 days−1 the Mediterranean basin's response to atmospheric pressure was not coherent and the performance of the model strongly depended on the specific area considered. A large amplitude seasonal oscillation observed in the experiments using a filtered free surface was not evident in the corresponding explicit free surface formulation case which was due to a phase shift between mass fluxes in the Gibraltar Strait and at the surface. The configuration with time splitting and atmospheric pressure always performed best; the differences were enhanced at very high frequencies.

  3. Investigation of acid-etched CO2 laser ablated enamel surfaces using polarization sensitive optical coherence tomography

    Science.gov (United States)

    Nahm, Byung J.; Kang, Hobin; Chan, Kenneth; Fried, Daniel

    2012-01-01

    A carbon dioxide laser operating at the highly absorbed wavelength of 9.3μm with a pulse duration of 10-15μs is ideally suited for caries removal and caries prevention. The enamel thermally modified by the laser has enhanced resistance to acid dissolution. This is an obvious advantage for caries prevention; however, it is often necessary to etch the enamel surface to increase adhesion to composite restorative materials and such surfaces may be more resistant to etching. The purpose of the study was to non-destructively measure the susceptibility of laser-ablated enamel surfaces to acid dissolution before and after acid-etching using Polarization Sensitive Optical Coherence Tomography (PS-OCT). PS-OCT was used to acquire images of bovine enamel surfaces after exposure to laser irradiation at ablative fluence, acid-etching, and a surface softened dissolution model. The integrated reflectivity from lesion and the lesion depth were measured using PS-OCT. Samples were also sectioned for examination by Polarized Light Microscopy (PLM). PS-OCT images showed that acid-etching greatly accelerated the formation of subsurface lesions on both laser-irradiated and non-irradiated surfaces (Penamel layer after 5-10 seconds.

  4. Sensitivity of Greenland Ice Sheet surface mass balance to perturbations in sea surface temperature and sea ice cover: a study with the regional climate model MAR

    Science.gov (United States)

    Noël, B.; Fettweis, X.; van de Berg, W. J.; van den Broeke, M. R.; Erpicum, M.

    2014-10-01

    During recent summers (2007-2012), several surface melt records were broken over the Greenland Ice Sheet (GrIS). The extreme summer melt resulted in part from a persistent negative phase of the North Atlantic Oscillation (NAO), favoring warmer atmospheric conditions than normal over the GrIS. Simultaneously, large anomalies in sea ice cover (SIC) and sea surface temperature (SST) were observed in the North Atlantic, suggesting a possible connection. To assess the direct impact of 2007-2012 SIC and SST anomalies on GrIS surface mass balance (SMB), a set of sensitivity experiments was carried out with the regional climate model MAR forced by ERA-Interim. These simulations suggest that perturbations in SST and SIC in the seas surrounding Greenland do not considerably impact GrIS SMB, as a result of the katabatic wind blocking effect. These offshore-directed winds prevent oceanic near-surface air, influenced by SIC and SST anomalies, from penetrating far inland. Therefore, the ice sheet SMB response is restricted to coastal regions, where katabatic winds cease. A topic for further investigation is how anomalies in SIC and SST might have indirectly affected the surface melt by changing the general circulation in the North Atlantic region, hence favoring more frequent warm air advection towards the GrIS.

  5. The Sensitivity of African Easterly Waves to Eastern Tropical Atlantic Sea-Surface Temperatures

    Science.gov (United States)

    Druyan, Leonard M.; Fulakeza, Matthew

    2011-01-01

    The results of two regional atmospheric model simulations are compared to assess the influence of the eastern tropical Atlantic sea-surface temperature maximum on local precipitation, transient easterly waves and the West African summer monsoon. Both model simulations were initialized with reanalysis 2 data (US National Center for Environmental Prediction and Department of Energy) on 15 May 2006 and extended through 6 October 2006, forced by synchronous reanalysis 2 lateral boundary conditions introduced four times daily. One simulation uses 2006 reanalysis 2 sea-surface temperatures, also updated four times daily, while the second simulation considers ocean forcing absent the sea-surface temperature maximum, achieved here by subtracting 3 K at every ocean grid point between 0 and 15 N during the entire simulation. The simulation with 2006 sea-surface temperature forcing produces a realistic distribution of June-September mean precipitation and realistic westward propagating swaths of maximum rainfall, based on validation against Tropical Rainfall Measuring Mission (TRMM) estimates. The simulation without the sea-surface temperature maximum produces only 57% of the control June-September total precipitation over the eastern tropical Atlantic and about 83% of the Sahel precipitation. The simulation with warmer ocean temperatures generates generally stronger circulation, which in turn enhances precipitation by increasing moisture convergence. Some local precipitation enhancement is also attributed to lower vertical thermal stability above the warm water. The study shows that the eastern tropical Atlantic sea-surface temperature maximum enhances the strength of transient easterly waves and broadens the spatial extent of associated precipitation. However, large-scale circulation and its interaction with the African continent, and not sea-surface temperatures, control the timing and trajectories of the waves.

  6. Estimating the Analytical and Surface Enhancement Factors in Surface-Enhanced Raman Scattering (SERS): A Novel Physical Chemistry and Nanotechnology Laboratory Experiment

    Science.gov (United States)

    Pavel, Ioana E.; Alnajjar, Khadijeh S.; Monahan, Jennifer L.; Stahler, Adam; Hunter, Nora E.; Weaver, Kent M.; Baker, Joshua D.; Meyerhoefer, Allie J.; Dolson, David A.

    2012-01-01

    A novel laboratory experiment was successfully implemented for undergraduate and graduate students in physical chemistry and nanotechnology. The main goal of the experiment was to rigorously determine the surface-enhanced Raman scattering (SERS)-based sensing capabilities of colloidal silver nanoparticles (AgNPs). These were quantified by…

  7. Parameter Estimation and Sensitivity Analysis of an Urban Surface Energy Balance Parameterization at a Tropical Suburban Site

    Science.gov (United States)

    Harshan, S.; Roth, M.; Velasco, E.

    2014-12-01

    Forecasting of the urban weather and climate is of great importance as our cities become more populated and considering the combined effects of global warming and local land use changes which make urban inhabitants more vulnerable to e.g. heat waves and flash floods. In meso/global scale models, urban parameterization schemes are used to represent the urban effects. However, these schemes require a large set of input parameters related to urban morphological and thermal properties. Obtaining all these parameters through direct measurements are usually not feasible. A number of studies have reported on parameter estimation and sensitivity analysis to adjust and determine the most influential parameters for land surface schemes in non-urban areas. Similar work for urban areas is scarce, in particular studies on urban parameterization schemes in tropical cities have so far not been reported. In order to address above issues, the town energy balance (TEB) urban parameterization scheme (part of the SURFEX land surface modeling system) was subjected to a sensitivity and optimization/parameter estimation experiment at a suburban site in, tropical Singapore. The sensitivity analysis was carried out as a screening test to identify the most sensitive or influential parameters. Thereafter, an optimization/parameter estimation experiment was performed to calibrate the input parameter. The sensitivity experiment was based on the "improved Sobol's global variance decomposition method" . The analysis showed that parameters related to road, roof and soil moisture have significant influence on the performance of the model. The optimization/parameter estimation experiment was performed using the AMALGM (a multi-algorithm genetically adaptive multi-objective method) evolutionary algorithm. The experiment showed a remarkable improvement compared to the simulations using the default parameter set. The calibrated parameters from this optimization experiment can be used for further model

  8. Structure-sensitive enantiospecific adsorption on naturally chiral Cu(hkl) R&S surfaces

    Science.gov (United States)

    Gellman, Andrew J.; Huang, Ye; Koritnik, Anjanette J.; Horvath, Joshua D.

    2017-01-01

    The desorption kinetics of a chiral compound, R-3-methylcyclohexanone (R-3MCHO), have been measured on both enantiomers of seven chiral Cu(hkl) R&S surfaces and on nine achiral Cu single crystal surfaces with surface structures that collectively span the various regions of the stereographic triangle. The naturally chiral surfaces have terrace-step-kink structures formed by all six possible combinations of the three low Miller index microfacets. The chirality of the kink sites is defined by the rotational orientation of the (1 1 1), (1 0 0) and (1 1 0) microfacets forming the kink. R-3MCHO adsorbs reversibly on these Cu surfaces and temperature programmed desorption has been used to measure its desorption energetics from the chiral kink sites. The desorption energies from the R- and S-kink sites are enantiospecific, Δ Δ E\\text{des}S-R= Δ E\\text{des}S- Δ E\\text{des}R\

  9. Surface analytical and electrochemical study on the role of adsorbed chloride ions in corrosion of stainless steels

    Energy Technology Data Exchange (ETDEWEB)

    Rossi, A.; Tulifero, R.; Elsener, B. [Cagliari Univ. (Italy). Dept. of Inorganic and Analytical Chemistry

    2001-03-01

    The pitting potential E{sub pit} of 18/8 CrNi stainless steels with different sulfur content (0.003, 0.017 and 0.29%) has been determined from potentiodynamic polarization curves in deaerated neutral solutions (0.1 M NaCl and 1 M Na{sub 2}SO{sub 4} + 0.1 M NaCl) with nominally identical chloride content. E{sub pit} decreased with increasing sulfur content of the alloy and was about 0.2 V more negative in pure 0.1 M NaCl solution. The chemical composition of the passive film and the adsorbed chloride content have been determined by XPS surface analysis on mechanically polished samples passivated for one hour at potentials below the pitting potential. XPS results show that the surface films are composed in all cases of mixed iron-chromium oxi-hydroxides with a higher chromium content than the bulk composition. The average passive film composition (ca. 40% chromium oxi-hydroxide) and the film thickness (2.3 {+-} 0.2 nm) were similar for all 18/8 CrNi steels regardless the different sulfur content. The amount of chlorides in the passive film is about twice as high on steels exposed to pure 0.1 N NaCl solution compared to the mixed 1 M Na{sub 2}SO{sub 4} + 0.1 M NaCl solution. Thus the lower pitting potential measured in pure 0.1 N NaCl solution correlates with the higher amount of chloride ions on the passive film surface. (orig.)

  10. Geochemical Principles and Methods of Assessment of Surface Water Environmental Impact on Sensitive Zones

    Institute of Scientific and Technical Information of China (English)

    程鸿德; 程林; 等

    1998-01-01

    This paper describes how to carry out environmental impact assessment in an environmentally sensitive zone.The principles,the train of thought and methods are proposed in this paper,We have made the water environmental impact assessment on the engineering project of technical reforms in Guiyang Battery Mill.The hasis for engineering construction and environmental protection in this mill has been laid dawn.

  11. Chapter 5: Modulation Excitation Spectroscopy with Phase-Sensitive Detection for Surface Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Shulda, Sarah; Richards, Ryan M.

    2016-02-19

    Advancements in in situ spectroscopic techniques have led to significant progress being made in elucidating heterogeneous reaction mechanisms. The potential of these progressive methods is often limited only by the complexity of the system and noise in the data. Short-lived intermediates can be challenging, if not impossible, to identify with conventional spectra analysis means. Often equally difficult is separating signals that arise from active and inactive species. Modulation excitation spectroscopy combined with phase-sensitive detection analysis is a powerful tool for removing noise from the data while simultaneously revealing the underlying kinetics of the reaction. A stimulus is applied at a constant frequency to the reaction system, for example, a reactant cycled with an inert phase. Through mathematical manipulation of the data, any signal contributing to the overall spectra but not oscillating with the same frequency as the stimulus will be dampened or removed. With phase-sensitive detection, signals oscillating with the stimulus frequency but with various lag times are amplified providing valuable kinetic information. In this chapter, some examples are provided from the literature that have successfully used modulation excitation spectroscopy with phase-sensitive detection to uncover previously unobserved reaction intermediates and kinetics. Examples from a broad range of spectroscopic methods are included to provide perspective to the reader.

  12. Sensitivity of surface radiation budget to clouds over the Asian monsoon region

    Indian Academy of Sciences (India)

    S Balachandran; M Rajeevan

    2007-04-01

    Using the ISCCP–FD surface radiative flux data for the summer season (June to September) of the period 1992 to 1995, an analysis was done to understand the role of clouds on the surface radiation budget over the Asian monsoon region. At the top of atmosphere (TOA) of convective regions of the Asian monsoon region, the short wave radiative forcing (SWCRF) and long wave radiative forcing (LWCRF) do not cancel each other resulting in occurrence of the net cloud radiative forcing values exceeding −30W/m2. This type of imbalance between SWCRF and LWCRF at TOA is reflected down on the earth surface–atmosphere system also as an imbalance between surface netcloud radiative forcing (NETCRF) and atmospheric NETCRF. Based on the regression analysis of the cloud effects on the surface radiation budget quantities, it has been observed that generally, the variance explained by multiple type cloud data is 50% more than that of total cloud cover alone. In case of SWCRF, the total cloud cover can explain about 3% (7%) of the variance whereas the three cloud type descriptions of clouds can explain about 44% (42%) of the variance over oceanic (land) regions. This highlights the importance of cloud type information in explaining the variations of surface radiation budget. It has been observed that the clouds produce more cooling effect in short-wave band than the warming effect in long-wave band resulting in a net cooling at the surface. Over the oceanic region, variations in high cloud amount contribute more to variations in SWCRF while over land regions both middle and high cloud variations make substantial contributions to the variations in both SWCRF and NETCRF.

  13. Simulated sensitivity of the tropical climate to extratropical thermal forcing: tropical SSTs and African land surface

    Science.gov (United States)

    Talento, Stefanie; Barreiro, Marcelo

    2016-08-01

    This study investigates the Intertropical Convergence Zone (ITCZ) response to extratropical thermal forcing applied to an atmospheric general circulation model coupled to slab ocean and land models. We focus on the relative roles of the atmosphere, tropical sea surface temperatures (SSTs) and continental surface temperatures in the ITCZ response to the imposed forcing. The forcing consists of cooling in one hemisphere and warming in the other poleward of 40°, with zero global average. Three sets of experiments are performed: in the first the slab ocean and land models are applied globally; in the second the tropical SSTs are kept fixed while the slab land model is applied globally; in the third, in addition, surface temperatures over Africa are kept fixed. Realistic boundary surface conditions are used. We find that the ITCZ shifts towards the warmer hemisphere and that the stronger the forcing, the larger the shift. When the constraint of fixed tropical SST is imposed we find that the ITCZ response is strongly weakened, but it is still not negligible in particular over the Atlantic Ocean and Africa where the precipitation anomalies are of the order of 20 and 60 %, respectively, of the magnitude obtained without the SST restriction. Finally, when the constraint of the African surface temperature is incorporated we find that the ITCZ response completely vanishes, indicating that the ITCZ response to the extratropical forcing is not possible just trough purely atmospheric processes, but needs the involvement of either the tropical SST or the continental surface temperatures. The clear-sky longwave radiation feedback is highlighted as the main physical mechanism operating behind the land-based extratropical to tropical communication.

  14. Polarization-sensitive surface plasmon enhanced ellipsometry biosensor using the photoelastic modulation technique

    DEFF Research Database (Denmark)

    Yuan, Scott Wu; Ho, Ho Pui; Wu, S.Y.

    2009-01-01

    A surface plasmon enhanced ellipsometry (SPEE) biosensor scheme based on the use of a photoelastic modulator (PEM) is reported. We show that the polarization parameters of a laser beam, tan , cos and ellipse orientation angle , can be directly measured by detecting the modulation signals at the f......A surface plasmon enhanced ellipsometry (SPEE) biosensor scheme based on the use of a photoelastic modulator (PEM) is reported. We show that the polarization parameters of a laser beam, tan , cos and ellipse orientation angle , can be directly measured by detecting the modulation signals...

  15. Hollow Au/Ag nanostars displaying broad plasmonic resonance and high surface-enhanced Raman sensitivity

    Science.gov (United States)

    Garcia-Leis, Adianez; Torreggiani, Armida; Garcia-Ramos, Jose Vicente; Sanchez-Cortes, Santiago

    2015-08-01

    Bimetallic Au/Ag hollow nanostar (HNS) nanoparticles with different morphologies were prepared in this work. These nanoplatforms were obtained by changing the experimental conditions (concentration of silver and chemical reductors, hydroxylamine and citrate) and by using Ag nanostars as template nanoparticles (NPs) through galvanic replacement. The goal of this research was to create bimetallic Au/Ag star-shaped nanoparticles with advanced properties displaying a broader plasmonic resonance, a cleaner exposed surface, and a high concentration of electromagnetic hot spots on the surface provided by the special morphology of nanostars. The size, shape, and composition of Ag as well as their optical properties were studied by extinction spectroscopy, hyperspectral dark field microscopy, transmission and scanning electron microscopy (TEM and SEM), and energy dispersive X-ray spectroscopy (EDX). Finally, the surface-enhanced Raman scattering (SERS) activity of these HNS was investigated by using thioflavin T, a biomarker of the β-amyloid fibril formation, responsible for Alzheimer's disease. Lucigenin, a molecule displaying different SERS activities on Au and Ag, was also used to explore the presence of these metals on the NP surface. Thus, a relationship between the morphology, plasmon resonance and SERS activity of these new NPs was made.Bimetallic Au/Ag hollow nanostar (HNS) nanoparticles with different morphologies were prepared in this work. These nanoplatforms were obtained by changing the experimental conditions (concentration of silver and chemical reductors, hydroxylamine and citrate) and by using Ag nanostars as template nanoparticles (NPs) through galvanic replacement. The goal of this research was to create bimetallic Au/Ag star-shaped nanoparticles with advanced properties displaying a broader plasmonic resonance, a cleaner exposed surface, and a high concentration of electromagnetic hot spots on the surface provided by the special morphology of nanostars

  16. Impact of nitrogen doping of niobium superconducting cavities on the sensitivity of surface resistance to trapped magnetic flux

    Science.gov (United States)

    Gonnella, Dan; Kaufman, John; Liepe, Matthias

    2016-02-01

    Future particle accelerators such as the SLAC "Linac Coherent Light Source-II" (LCLS-II) and the proposed Cornell Energy Recovery Linac require hundreds of superconducting radio-frequency (SRF) niobium cavities operating in continuous wave mode. In order to achieve economic feasibility of projects such as these, the cavities must achieve a very high intrinsic quality factor (Q0) to keep cryogenic losses within feasible limits. To reach these high Q0's in the case of LCLS-II, nitrogen-doping of niobium cavities has been selected as the cavity preparation technique. When dealing with Q0's greater than 1 × 1010, the effects of ambient magnetic field on Q0 become significant. Here, we show that the sensitivity to RF losses from trapped magnetic field in a cavity's walls is strongly dependent on the cavity preparation. Specifically, standard electropolished and 120 °C baked cavities show a sensitivity of residual resistance from trapped magnetic flux of ˜0.6 and ˜0.8 nΩ/mG trapped, respectively, while nitrogen-doped cavities show a higher sensitivity of residual resistance from trapped magnetic flux of ˜1 to 5 nΩ/mG trapped. We show that this difference in sensitivities is directly related to the mean free path of the RF surface layer of the niobium: shorter mean free paths lead to less sensitivity of residual resistance to trapped magnetic flux in the dirty limit (ℓ ≪ ξ0), while longer mean free paths lead to lower sensitivity of residual resistance to trapped magnetic flux in the clean limit (ℓ ≫ ξ0). These experimental results are also shown to have good agreement with recent theoretical predictions for pinned vortex lines oscillating in RF fields.

  17. Is Agency Skin Deep? Surface Attributes Influence Infants' Sensitivity to Goal-Directed Action

    Science.gov (United States)

    Guajardo, Jose J.; Woodward, Amanda L.

    2004-01-01

    Three studies investigated the role of surface attributes in infants' identification of agents, using a habituation paradigm designed to tap infants' interpretation of grasping as goal directed (Woodward, 1998). When they viewed a bare human hand grasping objects, 7- and 12-month-old infants focused on the relation between the hand and its goal.…

  18. Surface sensitivity of the spin Seebeck effect in the Pt/YIG system

    Science.gov (United States)

    Aqeel, Aisha; Vera-Marun, Ivan J.; van Wees, Bart J.; Palstra, Thomas T. M.

    2015-03-01

    It is well-known that the surface plays an important role in the spin Seebeck effect (SSE). However the effect of mechanical treatment on the SSE has not been systematically studied yet. Here, we have investigated the influence of the interface quality on the SSE in a bilayer system of platinum and yttrium iron garnet (Pt/YIG). The surfaces of the YIG crystals are modified by different types of mechanical polishing before Pt deposition for different samples. We observed that the magnitude and magnetic field dependence of the SSE is strongly influenced by mechanical treatment of the YIG surface. No definite relation has been found between the SSE response and the sample roughness. However, we observe a direct correlation between the saturation magnetic field (Hsat) of the SSE and the roughness of sample, as the former increases by moving from soft toward coarse particle polishing. The change in the magnitude of Hsat can be attributed to the presence of a perpendicular magnetic anisotropy due to the treatment induced surface strain or shape anisotropy in the Pt/YIG system.

  19. Sensitivity of the Meridional Overturning Circulation to the Pattern of the Surface Density Flux

    Science.gov (United States)

    2010-09-01

    a better prognosis of anthropogenic climate change . Figure 1. Classical representation of the global thermohaline circulation and oceanic...modeling efforts and long-term strategy related to climate change . 15. NUMBER OF PAGES 105 14. SUBJECT TERMS Meridional Overturning Circulation ... Thermohaline Circulation , Thermocline, Residual-Mean Theory, Air-Sea Fluxes, Surface Density Flux , Mixed-Layer Density, Water-mass Transformation

  20. The application of neoglycopeptides in the development of sensitive surface plasmon resonance-based biosensors

    NARCIS (Netherlands)

    Maljaars, C.E.P.; de Souza, A.C.; Halkes, K.M.; Upton, P.J.; Reeman, S.M.; André, S.; Gabius, H.-J.; McDonnell, M.B.; Kamerling, J.P.

    2008-01-01

    The development of a biosensor based on surface plasmon resonance is described for the detection of carbohydrate-binding proteins in solution on a Biacore 2000 instrument, using immobilized glycopeptides as ligands. Their selection was based on previous screenings of solid-phase glycopeptide

  1. The application of neoglycopeptides in the development of sensitive surface plasmon resonance-based biosensors

    NARCIS (Netherlands)

    Maljaars, C.E.P.; de Souza, A.C.; Halkes, K.M.; Upton, P.J.; Reeman, S.M.; André, S.; Gabius, H.-J.; McDonnell, M.B.; Kamerling, J.P.

    2008-01-01

    The development of a biosensor based on surface plasmon resonance is described for the detection of carbohydrate-binding proteins in solution on a Biacore 2000 instrument, using immobilized glycopeptides as ligands. Their selection was based on previous screenings of solid-phase glycopeptide librari

  2. ER-mitochondria contacts control surface glycan expression and sensitivity to killer lymphocytes in glioma stem-like cells.

    Science.gov (United States)

    Bassoy, Esen Yonca; Kasahara, Atsuko; Chiusolo, Valentina; Jacquemin, Guillaume; Boydell, Emma; Zamorano, Sebastian; Riccadonna, Cristina; Pellegatta, Serena; Hulo, Nicolas; Dutoit, Valérie; Derouazi, Madiha; Dietrich, Pierre Yves; Walker, Paul R; Martinvalet, Denis

    2017-06-01

    Glioblastoma is a highly heterogeneous aggressive primary brain tumor, with the glioma stem-like cells (GSC) being more sensitive to cytotoxic lymphocyte-mediated killing than glioma differentiated cells (GDC). However, the mechanism behind this higher sensitivity is unclear. Here, we found that the mitochondrial morphology of GSCs modulates the ER-mitochondria contacts that regulate the surface expression of sialylated glycans and their recognition by cytotoxic T lymphocytes and natural killer cells. GSCs displayed diminished ER-mitochondria contacts compared to GDCs. Forced ER-mitochondria contacts in GSCs increased their cell surface expression of sialylated glycans and reduced their susceptibility to cytotoxic lymphocytes. Therefore, mitochondrial morphology and dynamism dictate the ER-mitochondria contacts in order to regulate the surface expression of certain glycans and thus play a role in GSC recognition and elimination by immune effector cells. Targeting the mitochondrial morphology, dynamism, and contacts with the ER could be an innovative strategy to deplete the cancer stem cell compartment to successfully treat glioblastoma. © 2017 The Authors.

  3. Overcoming the polyethylene glycol dilemma via pathological environment-sensitive change of the surface property of nanoparticles for cellular entry.

    Science.gov (United States)

    Hama, Susumu; Itakura, Shoko; Nakai, Mayumi; Nakayama, Kayoko; Morimoto, Satoshi; Suzuki, Satoko; Kogure, Kentaro

    2015-05-28

    Modification with polyethylene glycol (PEG) is currently considered an important strategy for anti-cancer drug delivery, because PEGylated-nanoparticles would be effectively delivered to tumor tissue by enhanced permeation and retention effects. However, PEGylation suppresses the cellular uptake of nanoparticles (NPs) to target cells (known as the PEG dilemma). Here, we propose a novel strategy, namely conferring a pathological environment-sensitive property of nanoparticles for overcoming the PEG dilemma. Specifically, although nanoparticles have an overall negative surface charge to avoid interactions with biogenic substances in blood circulation, inversion of surface charge (to positive) at the pH of the tumor microenvironment may allow the nanoparticles to be taken up by cancer cells. To prove this concept, charge-invertible nanoparticles modified with novel slightly acidic pH-sensitive peptide (SAPSP-NPs) were developed. The negatively-charged SAPSP-NPs were delivered to tumor tissue, and were successfully taken up by cancer cells upon inversion of the surface charge to positive at intratumoral pH. SAPSP-NPs may serve as an alternative carrier to the PEGylated NP for anti-cancer drug delivery. Copyright © 2015 Elsevier B.V. All rights reserved.

  4. Analytic materials.

    Science.gov (United States)

    Milton, Graeme W

    2016-11-01

    The theory of inhomogeneous analytic materials is developed. These are materials where the coefficients entering the equations involve analytic functions. Three types of analytic materials are identified. The first two types involve an integer p. If p takes its maximum value, then we have a complete analytic material. Otherwise, it is incomplete analytic material of rank p. For two-dimensional materials, further progress can be made in the identification of analytic materials by using the well-known fact that a 90(°) rotation applied to a divergence-free field in a simply connected domain yields a curl-free field, and this can then be expressed as the gradient of a potential. Other exact results for the fields in inhomogeneous media are reviewed. Also reviewed is the subject of metamaterials, as these materials provide a way of realizing desirable coefficients in the equations.

  5. Analytic Materials

    CERN Document Server

    Milton, Graeme W

    2016-01-01

    The theory of inhomogeneous analytic materials is developed. These are materials where the coefficients entering the equations involve analytic functions. Three types of analytic materials are identified. The first two types involve an integer $p$. If $p$ takes its maximum value then we have a complete analytic material. Otherwise it is incomplete analytic material of rank $p$. For two-dimensional materials further progress can be made in the identification of analytic materials by using the well-known fact that a $90^\\circ$ rotation applied to a divergence free field in a simply connected domain yields a curl-free field, and this can then be expressed as the gradient of a potential. Other exact results for the fields in inhomogeneous media are reviewed. Also reviewed is the subject of metamaterials, as these materials provide a way of realizing desirable coefficients in the equations.

  6. Organic and inorganic surface passivations of TiO2 nanotube arrays for dye-sensitized photoelectrodes

    Science.gov (United States)

    Park, Hun; Yang, Changduk; Choi, Won-Youl

    2012-10-01

    Surface passivation of photoelectrodes is widely used to improve the performance of dye-sensitized solar cells (DSCs). We use the organic and inorganic materials as a surface-passivating layer of photoelectrodes and introduce the effect of surface passivation on the power conversion efficiency of DSCs. TiO2 nanotube arrays are fabricated by anodic oxidation of Ti foil for photoelectrodes of DSCs. Surface passivating layers are conducted by immersing photoelectrode in various precursor solutions. MgO and WO3 are selected for inorganic passivation. PC61BM is used for organic passivation. In case of inorganic passivation, a basic material (MgO) which has a high isoelectric point (pI >7) shows higher power conversion efficiency of 2.63% by increasing of open circuit voltage (Voc) to 0.74 V than bare sample of 2.55%. But, an acidic material (WO3) shifts Voc to low potential resulting in a worse efficiency of DSCs. In case of organic passivation, PC61BM enhances photocurrents and decreases Voc value compared to bare sample. The power conversion efficiency of PC61BM-coated DSCs is overall improved due to enhanced photocurrents despite of Voc offset to low potential. Back-transfer electron blocking, dye adsorption, TiO2 conduction band shifting, and additional charge generation by surface passivation are discussed.

  7. Analytical Modeling for Mechanical Strength Prediction with Raman Spectroscopy and Fractured Surface Morphology of Novel Coconut Shell Powder Reinforced: Epoxy Composites

    Science.gov (United States)

    Singh, Savita; Singh, Alok; Sharma, Sudhir Kumar

    2016-06-01

    In this paper, an analytical modeling and prediction of tensile and flexural strength of three dimensional micro-scaled novel coconut shell powder (CSP) reinforced epoxy polymer composites have been reported. The novel CSP has a specific mixing ratio of different coconut shell particle size. A comparison is made between obtained experimental strength and modified Guth model. The result shows a strong evidence for non-validation of modified Guth model for strength prediction. Consequently, a constitutive modeled equation named Singh model has been developed to predict the tensile and flexural strength of this novel CSP reinforced epoxy composite. Moreover, high resolution Raman spectrum shows that 40 % CSP reinforced epoxy composite has high dielectric constant to become an alternative material for capacitance whereas fractured surface morphology revealed that a strong bonding between novel CSP and epoxy polymer for the application as light weight composite materials in engineering.

  8. Second harmonic generation in metal nano-spheres: full-wave analytical solution with both local-surface and nonlocal-bulk nonlinear sources

    CERN Document Server

    Capretti, Antonio; Negro, Luca Dal; Miano, Giovanni

    2013-01-01

    We present a full-wave analytical solution for the problem of second-harmonic generation from spherical particles made of lossy centrosymmetric materials. Both the local-surface and nonlocalbulk nonlinear sources are included in the generation process, under the undepleted-pump approximation. The solution is derived in the framework of the Mie theory by expanding the pump field, the non-linear sources and the second-harmonic fields in series of spherical vector wave functions. We apply the proposed solution to the second-harmonic generation properties of noble metal nano-spheres as function of the polarization, the pump wavelength and the particle size. This approach provides a rigorous methodology to understand second-order optical processes in metal nanoparticles, and to design novel nanoplasmonic devices in the nonlinear regime.

  9. A Green Analytical Procedure for Sensitive and Selective Determination of Arsenic in Scalp Hair Samples of Arsenic Exposed Adults of Both Genders

    Directory of Open Access Journals (Sweden)

    Jameel A. Baig

    2010-12-01

    Full Text Available A green analytical procedure based on cloud point extraction (CPE is proposed for arsenic determination in biological samples (scalp hair. The scalp hair samples were subjected to microwave assisted digestison in a mixture of nitric acid and hydrogen peroxide (2:1 ratio, prior to preconcentration by CPE. Arsenic in digested samples of scalp hair was formed complex with ammonium pyrrolidine dithiocarbamate (APDC, and resulted As-PDC complex was extracted by a non-ionic surfactant octylphenoxypolyethoxyethanol (Triton X-114, after centrifugation the surfactant-rich phase was diluted with 0.1 mol L−1 HNO3 in methanol. For optimum recovery of analyte, the influence of the analytical parameters including pH, amounts of complexing and surfactant reagents were investigated. An enrichment factor of 50 was obtained for the preconcentration of As. Limit of detection and quantitation obtained under the optimal conditions were 0.03 and 0.11 µg kg-1, respectively. The obtained result showed sufficient recovery (> 98% for As in certified reference material of human hair (BCR 397. The developed method was applied to the determination of As in scalp hair samples of male and female subjects of two villages of Hyderabad, Pakistan.

  10. New sensitive micro-measurements of dynamic surface tension and diffusion coefficients

    DEFF Research Database (Denmark)

    Kinoshita, Koji; Ortiz, Elisa Parra; Needham, David

    2017-01-01

    . These limitations create inconsistencies for the kinetic analysis of surfactant adsorption/desorption, especially significant for ionic surfactants. Here, the “micropipette interfacial area-expansion method” was introduced and validated as a new DST measurement having a high enough sensitivity to detect diffusion...... controlled molecular adsorption at the air-water interfaces. To validate the new technique, the diffusion coefficient of 1-Octanol in water was investigated with existing models: the Ward Tordai model for the long time adsorption regime (1–100 s), and the Langmuir and Frumkin adsorption isotherm models...

  11. Single-beam self-referenced phase-sensitive surface plasmon resonance sensor with high detection resolution

    Institute of Scientific and Technical Information of China (English)

    Shu-Yuen Wu; Ho-Pui Ho

    2008-01-01

    A versatile and low-cost single-beam self-referenced phase-sensitive surface plasmon resonance(SPR)sensing system with ultra-high resolution performance is presented.The system exhibits a root-mean-square phase fluctuation of ±0.0028.over a period of 45 min.i.e.a resolution of±5.2×10-9 refractive index units.The enhanced performance has been achieved through the incorporation of three design elements:a true single-beam configuration enabling complete self-referencing so that only the phase change associated with SPR gets detected,a differential measurement scheme to eliminate spurious signals not related to the sensor response,and the elimination of retardation drifts by incorporating temperature stabilization in the liquid crystal phase modulato .Our design should bring the detection sensitivity of non-labeling SPR biosensing closer to that achievable by conventional fluorescence-based techniques.

  12. A Gold Nanoparticles Enhanced Surface Plasmon Resonance Immunosensor for Highly Sensitive Detection of Ischemia-Modified Albumin

    Directory of Open Access Journals (Sweden)

    Guang Li

    2013-09-01

    Full Text Available In this study a novel sensitive nanogold particle sensor enhancement based on mixed self-assembled monolayers was explored and used to construct a Surface Plasmon Resonance (SPR immunosensor to detect Ischemia Modified Albumin (IMA. Compared with a direct binding SPR assay at a limit of detection (LOD of 100 ng/L, gold nanoparticles (AuNPs of 10 nm dramatically improved the LOD of IMA to 10 ng/L. Meanwhile, no interfering substance that may lead to false positive results was identified. These results suggested that the SPR biosensor presented superior properties, and provided a simple label-free strategy to increase assay sensitivity for further acute coronary syndrome (ACS diagnosis.

  13. Analytic trigonometry

    CERN Document Server

    Bruce, William J; Maxwell, E A; Sneddon, I N

    1963-01-01

    Analytic Trigonometry details the fundamental concepts and underlying principle of analytic geometry. The title aims to address the shortcomings in the instruction of trigonometry by considering basic theories of learning and pedagogy. The text first covers the essential elements from elementary algebra, plane geometry, and analytic geometry. Next, the selection tackles the trigonometric functions of angles in general, basic identities, and solutions of equations. The text also deals with the trigonometric functions of real numbers. The fifth chapter details the inverse trigonometric functions

  14. Analytical Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — The Analytical Labspecializes in Oil and Hydraulic Fluid Analysis, Identification of Unknown Materials, Engineering Investigations, Qualification Testing (to support...

  15. Phase-sensitive lock-in imaging of surface densities of states

    Science.gov (United States)

    Svec, Martin; Mutombo, Pingo; Shukrinov, Pavel; Dudr, Viktor; Cháb, Vladimír

    2006-01-01

    A new way of imaging the local density of states has been devised through a combination of the constant-height scanning tunnelling microscopy operational mode and lock-in techniques. We have obtained current images simultaneously with real space dynamical conductance maps (d I/d V) for energies around the Fermi level, on the Si(111)-(7 × 7) surface. We reconstructed the normalized dynamical conductance spectra—(d I/d V)/(I/V). Since the (d I/d V)/(I/V) curves are closely related to the local densities of states, we compared their sum over the unit cell to photoelectron spectra and theoretical calculations. We find that the results are in good agreement. Consequently, the extent of localization of surface electronic states at lattice positions was determined.

  16. Surface-sensitive conductivity measurement using a micro multi-point probe approach.

    Science.gov (United States)

    Perkins, Edward; Barreto, Lucas; Wells, Justin; Hofmann, Philip

    2013-03-01

    An instrument for microscale electrical transport measurements in ultra-high vacuum is presented. The setup is constructed around collinear lithographically-created multi-point probes with a contact spacing down to 500 nm. Most commonly, twelve-point probes are used. These probes are approached to the surface via piezoelectric positioners. Standard four-point resistance measurements can be performed using any combination of contacts out of the twelve available. Current/voltage measurements are taken semi-automatically for a variety of the possible contact configurations, effectively emulating measurements with an equidistant four-point probe for a wide range of contact spacings. In this way, it is possible to distinguish between bulk-like and surface-like conduction. The paper describes the design of the instrument and the approach to data and error analysis. Application examples are given for epitaxial graphene on SiC and degenerately doped Bi₂Se₃.

  17. Sensitive response of the Greenland Ice Sheet to surface melt drainage over a soft bed.

    Science.gov (United States)

    Bougamont, M; Christoffersen, P; Hubbard, A L; Fitzpatrick, A A; Doyle, S H; Carter, S P

    2014-09-29

    The dynamic response of the Greenland Ice Sheet (GrIS) depends on feedbacks between surface meltwater delivery to the subglacial environment and ice flow. Recent work has highlighted an important role of hydrological processes in regulating the ice flow, but models have so far overlooked the mechanical effect of soft basal sediment. Here we use a three-dimensional model to investigate hydrological controls on a GrIS soft-bedded region. Our results demonstrate that weakening and strengthening of subglacial sediment, associated with the seasonal delivery of surface meltwater to the bed, modulates ice flow consistent with observations. We propose that sedimentary control on ice flow is a viable alternative to existing models of evolving hydrological systems, and find a strong link between the annual flow stability, and the frequency of high meltwater discharge events. Consequently, the observed GrIS resilience to enhanced melt could be compromised if runoff variability increases further with future climate warming.

  18. Enhancing the sensitivity of three-axis detectable surface acoustic wave gyroscope by using a floating thin piezoelectric membrane

    Science.gov (United States)

    Lee, Munhwan; Lee, Keekeun

    2017-06-01

    A new type of surface acoustic wave (SAW) gyroscope was developed on a floating thin piezoelectric membrane to enhance sensitivity and reliability by removing a bulk noise effect and by importing a higher amplitude of SAW. The developed device constitutes a two-port SAW resonator with a metallic dot array between two interdigital transducers (IDTs), and a one-port SAW delay line. The bulk silicon was completely etched away, leaving only a thin piezoelectric membrane with a thickness of one wavelength. A voltage controlled oscillator (VCO) was connected to a SAW resonator to activate the SAW resonator, while the SAW delay line was connected to the oscilloscope to monitor any variations caused by the Coriolis force. When the device was rotated, a secondary wave was generated, changing the amplitude of the SAW delay line. The highest sensitivity was observed in a device with a full acoustic wavelength thickness of the membrane because most of the acoustic field is confined within an acoustic wavelength thickness from the top surface; moreover, the thin-membrane-based gyroscope eliminates the bulk noise effect flowing along the bulk substrate. The obtained sensitivity and linearity of the SAW gyroscope were ˜27.5 µV deg-1 s-1 and ˜4.3%, respectively. Superior directivity was observed. The device surface was vacuum-sealed using poly(dimethylsiloxane) (PDMS) bonding to eliminate environmental interference. A three-axis detectable gyroscope was also implemented by placing three gyrosensors with the same configuration at right angles to each other on a printed circuit board.

  19. Manipulating the Surface Chemistry of Quantum Dots for Sensitive Ratiometric Fluorescence Detection of Sulfur Dioxide.

    Science.gov (United States)

    Li, Huihui; Zhu, Houjuan; Sun, Mingtai; Yan, Yehan; Zhang, Kui; Huang, Dejian; Wang, Suhua

    2015-08-11

    Herein, we report a novel approach to the rapid visual detection of gaseous sulfur dioxide (SO2) by manipulating the surface chemistry of 3-aminopropyltriethoxysilane (APTS)-modified quantum dots (QDs) using fluorescent coumarin-3-carboxylic acid (CCA) for specific reaction with SO2. The CCA molecules are attached to the surface amino groups of the QDs through electrostatic attraction, thus the fluorescence of CCA is greatly suppressed because of the formation of an ion-pair complex between the ATPS-modified QDs and CCA. Such an interaction is vulnerable to SO2 because SO2 can readily react with surface amino groups to form strong charge-transfer complexes and subsequently release the strongly fluorescent CCA molecules. The mechanism has been carefully verified through a series of control experiments. Upon exposure to different amounts of SO2, the fluorescent color of the nanoparticle-based sensor displays continuously changes from red to blue. Most importantly, the approach owns high selectivity for SO2 and a tolerance of interference, which enables the sensor to detect SO2 in a practical application. Using this fluorescence-based sensing method, we have achieved a visual detection limit of 6 ppb for gaseous SO2.

  20. Electroless-plated gold films for sensitive surface plasmon resonance detection of white spot syndrome virus.

    Science.gov (United States)

    Lei, Yun; Chen, Hongyu; Dai, Heping; Zeng, Zhaorui; Lin, Yi; Zhou, Feimeng; Pang, Daiwen

    2008-02-28

    The paper describes the rapid and label-free detection of the white spot syndrome virus (WSSV) using a surface plasmon resonance (SPR) device based on gold films prepared by electroless plating. The plating condition for obtaining films suitable for SPR measurements was optimized. Gold nanoparticles adsorbed on glass slides were characterized by transmission electron microscopy (TEM). Detection of the WSSV was performed through the binding between WSSV in solution and the anti-WSSV single chain variable fragment (scFv antibody) preimmobilized onto the sensor surface. Morphologies of the as-prepared gold films, gold films modified with self-assembled alkanethiol monolayers, and films covered with antibody were examined using an atomic force microscope (AFM). To demonstrate the viability of the method for real sample analysis, WSSV of different concentrations present in a shrimp hemolymph matrix was determined upon optimizing the surface density of the antibody molecules. The SPR device based on the electroless-plated gold films is capable of detecting concentration of WSSV as low as 2.5 ng/mL in 2% shrimp hemolymph, which is one to two orders of magnitude lower than the level measurable by enzyme-linked immunosorbant assays.

  1. Surface initiated polymerization of a cationic monomer on inner surfaces of silica capillaries: analyte separation by capillary electrophoresis versus polyelectrolyte behavior.

    Science.gov (United States)

    Witos, Joanna; Karesoja, Mikko; Karjalainen, Erno; Tenhu, Heikki; Riekkola, Marja-Liisa

    2013-03-01

    [2-(Methacryloyl)oxyethyl]trimethylammonium chloride was successfully polymerized by surface-initiated atom transfer radical polymerization method on the inner surface of fused-silica capillaries resulting in a covalently bound poly([2-(methacryloyl)oxyethyl]trimethylammonium chloride) coating. The coated capillaries provided in capillary electrophoresis an excellent run-to-run repeatability, capillary-to-capillary and day-to-day reproducibility. The capillaries worked reliably over 1 month with EOF repeatability below 0.5%. The positively charged coated capillaries were successfully applied to the capillary electrophoretic separation of three standard proteins and five β-blockers with the separation efficiencies ranging from 132,000 to 303,000 plates/m, and from 82,000 to 189,000 plates/m, respectively. In addition, challenging high- and low-density lipoprotein particles could be separated. The hydrodynamic sizes of free polymer chains in buffers used in the capillary electrophoretic experiments were measured for the characterization of the coatings.

  2. One-dimensional model of interacting-step fluctuations on vicinal surfaces: Analytical formulas and kinetic Monte-Carlo simulations

    Science.gov (United States)

    Patrone, Paul; Einstein, T. L.; Margetis, Dionisios

    2011-03-01

    We study a 1+1D, stochastic, Burton-Cabrera-Frank (BCF) model of interacting steps fluctuating on a vicinal crystal. The step energy accounts for entropic and nearest-neighbor elastic-dipole interactions. Our goal is to formulate and validate a self-consistent mean-field (MF) formalism to approximately solve the system of coupled, nonlinear stochastic differential equations (SDEs) governing fluctuations in surface motion. We derive formulas for the time-dependent terrace width distribution (TWD) and its steady-state limit. By comparison with kinetic Monte-Carlo simulations, we show that our MF formalism improves upon models in which step interactions are linearized. We also indicate how fitting parameters of our steady state MF TWD may be used to determine the mass transport regime and step interaction energy of certain experimental systems. PP and TLE supported by NSF MRSEC under Grant DMR 05-20471 at U. of Maryland; DM supported by NSF under Grant DMS 08-47587.

  3. A simple and sensitive quantitation of N,N-dimethyltryptamine by gas chromatography with surface ionization detection.

    Science.gov (United States)

    Ishii, A; Seno, H; Suzuki, O; Hattori, H; Kumazawa, T

    1997-01-01

    A simple and sensitive method for determination of N,N-dimethyltryptamine (DMT) by gas chromatography (GC) with surface ionization detection (SID) is presented. Whole blood or urine, containing DMT and gramine (internal standard), was subjected to solid-phase extraction with a Sep-Pak C18 cartridge before analysis by GC-SID. The calibration curve was linear in the DMT range of 1.25-20 ng/mL blood or urine. The detection limit of DMT was about 0.5 ng/mL (10 pg on-column). The recovery of both DMT and gramine spiked in biological fluids was above 86%.

  4. The sensitivity of the Late Saalian (140 ka) and LGM (21 ka) Eurasian ice sheets to sea surface conditions

    Energy Technology Data Exchange (ETDEWEB)

    Colleoni, Florence [Centro Euro-Mediterraneo per i Cambiamenti Climatici, Bologna (Italy); UJF, CNRS, Laboratoire de Glaciologie et Geophysique de l' Environnement, Saint Martin d' Heres Cedex (France); Stockholm University, Department of Geological Sciences, Stockhlom (Sweden); Liakka, Johan [Stockholm University, Department of Meteorology, Stockholm (Sweden); Krinner, Gerhard; Peyaud, Vincent [UJF, CNRS, Laboratoire de Glaciologie et Geophysique de l' Environnement, Saint Martin d' Heres Cedex (France); Jakobsson, Martin [Stockholm University, Department of Geological Sciences, Stockhlom (Sweden); Masina, Simona [Centro Euro-Mediterraneo per i Cambiamenti Climatici, Istituto Nazionale di Geofisica e Vulcanologia, Bologna (Italy)

    2011-08-15

    This work focuses on the Late Saalian (140 ka) Eurasian ice sheets' surface mass balance (SMB) sensitivity to changes in sea surface temperatures (SST). An Atmospheric General Circulation Model (AGCM), forced with two preexisting Last Glacial Maximum (LGM, 21 ka) SST reconstructions, is used to compute climate at 140 and 21 ka (reference glaciation). Contrary to the LGM, the ablation almost stopped at 140 ka due to the climatic cooling effect from the large ice sheet topography. Late Saalian SST are simulated using an AGCM coupled with a mixed layer ocean. Compared to the LGM, these 140 ka SST show an inter-hemispheric asymmetry caused by the larger ice-albedo feedback, cooling climate. The resulting Late Saalian ice sheet SMB is smaller due to the extensive simulated sea ice reducing the precipitation. In conclusion, SST are important for the stability and growth of the Late Saalian Eurasian ice sheet. (orig.)

  5. Metal-Free Counter Electrode for Efficient Dye-Sensitized Solar Cells through High Surface Area and Large Porous Carbon

    Directory of Open Access Journals (Sweden)

    Pavuluri Srinivasu

    2011-01-01

    Full Text Available Highly efficient, large mesoporous carbon is fabricated as a metal-free counter electrode for dye-sensitized solar cells. The mesoporous carbon shows very high energy conversion efficiency of 7.1% compared with activated carbon. The mesoporous carbon is prepared and characterized by nitrogen adsorption, scanning electron microscopy (SEM, and transmission electron microscopy (TEM. The nitrogen adsorption data reveals that the material possesses BET specific surface area ca.1300 m2/g and pore diameter 4.4 nm. Hexagonal rod-like morphology and ordered pore structure of mesoporous carbon are confirmed by electron microscopy data. The better performance of this carbon material is greatly benefited from its ordered interconnected mesoporous structure and high surface area.

  6. Sensitivity of surface resistance measurement of HTS thin films by cavity resonator, dielectric resonator and microstrip line resonator

    Indian Academy of Sciences (India)

    N D Kataria; Mukul Misra; R Pinto

    2002-05-01

    Microwave surface resistance s of silver-doped YBa2Cu3O7- (YBCO) thin film, deposited by laser ablation technique on 10 mm × 10 mm LaAlO3 substrate, has been measured by resonant techniques in the frequency range from 5 GHz to 20 GHz. The geometrical factor of the sample and the resonator has been determined theoretically by the knowledge of the electromagnetic field distribution in the resonators. The microwave surface resistance of the superconducting sample is then extracted from the measured value as a function of temperature. The sensitivity of the s measurement, that is, the relative change in the value with the change in the s value is determined for each resonator.

  7. Sensitivity of thermal inertia calculations to variations in environmental factors. [in mapping of Earth's surface by remote sensing

    Science.gov (United States)

    Kahle, A. B.; Alley, R. E.; Schieldge, J. P.

    1984-01-01

    The sensitivity of thermal inertia (TI) calculations to errors in the measurement or parameterization of a number of environmental factors is considered here. The factors include effects of radiative transfer in the atmosphere, surface albedo and emissivity, variations in surface turbulent heat flux density, cloud cover, vegetative cover, and topography. The error analysis is based upon data from the Heat Capacity Mapping Mission (HCMM) satellite for July 1978 at three separate test sites in the deserts of the western United States. Results show that typical errors in atmospheric radiative transfer, cloud cover, and vegetative cover can individually cause root-mean-square (RMS) errors of about 10 percent (with atmospheric effects sometimes as large as 30-40 percent) in HCMM-derived thermal inertia images of 20,000-200,000 pixels.

  8. Photocurrent enhancement by surface plasmon resonance of silver nanoparticles in highly porous dye-sensitized solar cells.

    Science.gov (United States)

    Jeong, Nak Cheon; Prasittichai, Chaiya; Hupp, Joseph T

    2011-12-06

    Localized surface plasmon resonance (LSPR) by silver nanoparticles that are photochemically incorporated into an electrode-supported TiO(2) nanoparticulate framework enhances the extinction of a subsequently adsorbed dye (the ruthenium-containing molecule, N719). The enhancement arises from both an increase in the dye's effective absorption cross section and a modest increase in the framework surface area. Deployment of the silver-modified assembly as a photoanode in dye-sensitized solar cells leads to light-to-electrical energy conversion with an overall efficiency of 8.9%. This represents a 25% improvement over the performance of otherwise identical solar cells lacking corrosion-protected silver nanoparticles. As one would expect based on increased dye loading and electromagnetic field enhanced (LSPR-enhanced) absorption, the improvement is manifested chiefly as an increase in photocurrent density ascribable to improved light harvesting.

  9. Sensitivity of thermal inertia calculations to variations in environmental factors. [in mapping of Earth's surface by remote sensing

    Science.gov (United States)

    Kahle, A. B.; Alley, R. E.; Schieldge, J. P.

    1984-01-01

    The sensitivity of thermal inertia (TI) calculations to errors in the measurement or parameterization of a number of environmental factors is considered here. The factors include effects of radiative transfer in the atmosphere, surface albedo and emissivity, variations in surface turbulent heat flux density, cloud cover, vegetative cover, and topography. The error analysis is based upon data from the Heat Capacity Mapping Mission (HCMM) satellite for July 1978 at three separate test sites in the deserts of the western United States. Results show that typical errors in atmospheric radiative transfer, cloud cover, and vegetative cover can individually cause root-mean-square (RMS) errors of about 10 percent (with atmospheric effects sometimes as large as 30-40 percent) in HCMM-derived thermal inertia images of 20,000-200,000 pixels.

  10. Gold nanoparticles as a substrate in bio-analytical near-infrared surface-enhanced Raman spectroscopy.

    Science.gov (United States)

    Butler, Holly J; Fogarty, Simon W; Kerns, Jemma G; Martin-Hirsch, Pierre L; Fullwood, Nigel J; Martin, Francis L

    2015-05-07

    As biospectroscopy techniques continue to be developed for screening or diagnosis within a point-of-care setting, an important development for this field will be high-throughput optimization. For many of these techniques, it is therefore necessary to adapt and develop parameters to generate a robust yet simple approach delivering high-quality spectra from biological samples. Specifically, this is important for surface-enhanced Raman spectroscopy (SERS) wherein there are multiple variables that can be optimised to achieve an enhancement of the Raman signal from a sample. One hypothesis is that "large" diameter (>100 nm) gold nanoparticles provide a greater enhancement at near-infrared (NIR) and infrared (IR) wavelengths than those gold nanoparticles. It was found that 150 nm gold nanoparticles are an excellent material for NIR/IR SERS. Larger gold nanoparticles may better satisfy the theoretical restraints for SERS enhancement at NIR/IR wavelengths compared to smaller nanoparticles. Also, larger nanoparticles or their aggregates are more readily observed via optical microscopy (and especially electron microscopy) compared to smaller ones. This allows rapid and straightforward identification of target areas containing a high concentration of nanoparticles and facilitating SERS spectral acquisition. To some extent, these observations appear to extend to biofluids such as blood plasma or (especially) serum; SERS spectra of such biological samples often exhibit a low signal-to-noise ratio in the absence of nanoparticles. With protein-rich biofluids such as serum, a dramatic SERS effect can be observed; although this might facilitate improved spectral biomarker identification in the future, it may not always improve classification between control vs. cancer. Thus, use of "large" gold nanoparticles are a good starting point in order to derive informative NIR/IR SERS analysis of biological samples.

  11. Pulsed laser deposited Ag nanoparticles on nickel hydroxide nanosheet arrays for highly sensitive surface-enhanced Raman scattering spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Jing, Yuting; Wang, Huanwen; Chen, Xiao [Department of Chemistry, Tongji University, Shanghai 200092 (China); Wang, Xuefeng, E-mail: xfwang@tongji.edu.cn [Department of Chemistry, Tongji University, Shanghai 200092 (China); Wei, Huige [Integrated Composites Laboratory (ICL), Dan F. Smith Department of Chemical Engineering, Lamar University, Beaumont, Texas 77710 (United States); Guo, Zhanhu, E-mail: zhanhu.guo@lamar.edu [Integrated Composites Laboratory (ICL), Dan F. Smith Department of Chemical Engineering, Lamar University, Beaumont, Texas 77710 (United States)

    2014-10-15

    Highlights: • Silver nanoparticles (NPs) were deposited on nickel hydroxide nanosheet (NS) arrays by pulsed laser deposition (PLD) for surface-enhanced Raman scattering (SERS) spectroscopy. • The Ag/Ni(OH){sub 2} composite film exhibits very high Raman scattering enhancement ability, possessing an enhancement factor as high as 5 × 10{sup 6}. • The enhancement ability of the substrate was strongly dependent on the size and interparticle gap of Ag NPs. • The 3D structure of Ni(OH){sub 2} NS arrays and the charge transfer of Ag NPs may be responsible for this high sensitivity Raman phenomenon. - Abstract: In the present work, silver nanoparticles (NPs) were deposited on nickel hydroxide nanosheet (NS) arrays by pulsed laser deposition (PLD) for surface-enhanced Raman scattering (SERS) spectroscopy. The effective high specific surface area with silver NPs decorated on the NS arrays was revealed by field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The microstructure and optical property of this three-dimensional (3D) substrate were investigated by X-ray diffraction (XRD) and UV–vis spectra, respectively. Using rhodamine 6G (R6G) as probe molecules with the concentration down to 10{sup −5} M, the Ag/Ni(OH){sub 2} composite film exhibits very high Raman scattering enhancement ability, possessing an enhancement factor as high as 5 × 10{sup 6}. It has been found that the enhancement ability of the substrate was strongly dependent on the size and interparticle gap of Ag NPs rather than the testing position on the film surface. In addition, the 3D structure of Ni(OH){sub 2} NS arrays and the charge transfer of Ag NPs may be responsible for this high sensitivity Raman phenomenon.

  12. Enhanced detection sensitivity of Escherichia coli O157:H7 using surface-modified gold nanorods

    Directory of Open Access Journals (Sweden)

    Ramasamy M

    2015-08-01

    Full Text Available Mohankandhasamy Ramasamy,1 Dong Kee Yi,2,3 Seong Soo A An4 1School of Chemical Engineering, Yeungnam University, Gyeongsan, 2Department of Chemistry, 3Department of Energy and Biotechnology, Myongji University, Yongin, 4Department of BioNano Technology, Gachon University, Seongnam, Republic of Korea Abstract: Escherichia coli O157:H7 (O157 is a Gram negative and highly virulent bacteria found in food and water sources, and is a leading cause of chronic diseases worldwide. Diagnosis and prevention from the infection require simple and rapid analysis methods for the detection of pathogens, including O157. Endogenous membrane peroxidase, an enzyme present on the surface of O157, was used for the colorimetric detection of bacteria by catalytic oxidation of the peroxidase substrate. In this study, we have analyzed the impact of the synthesized bare gold nanorods (AuNRs and silica-coated AuNRs on the growth of E. coli O157. Along with the membrane peroxidase activity of O157, other bacteria strains were analyzed. Different concentrations of nanorods were used to analyze the growth responses, enzymatic changes, and morphological alterations of bacteria by measuring optical density, 3,3',5,5'-tetramethylbenzidine assay, flow cytometry analysis, and microscopy studies. The results revealed that O157 showed higher and continuous membrane peroxidase activity than other bacteria. Furthermore, O157 treated with bare AuNRs showed a decreased growth rate in comparison with the bacteria with surface modified AuNRs. Interestingly, silica-coated AuNRs favored the growth of bacteria and also increased membrane peroxidase activity. This result can be particularly important for the enzymatic analysis of surface treated AuNRs in various microbiological applicants. Keywords: E. coli, O157:H7, endogenous membrane peroxidase, gold nanorod, silica-coated gold nanorod

  13. Instantaneous generation of charge-separated state on TiO₂ surface sensitized with plasmonic nanoparticles.

    Science.gov (United States)

    Long, Run; Prezhdo, Oleg V

    2014-03-19

    Photoexcitation of the plasmon band in metallic nanoparticles adsorbed on a TiO2 surface initiates many important photovoltaic and photocatalytic processes. The traditional view on the photoinduced charge separation involves excitation of a surface plasmon, its subsequent dephasing into electron-hole pairs, followed by electron transfer (ET) from the metal nanoparticle into TiO2. We use nonadiabatic molecular dynamics combined with time-domain density functional theory to demonstrate that an electron appears inside TiO2 immediately upon photoexcitation with a high probability (~50%), bypassing the intermediate step of electron-hole thermalization inside the nanoparticle. By providing a detailed, atomistic description of the charge separation, energy relaxation, and electron-hole recombination processes, the simulation rationalizes why the experimentally observed ultrafast photoinduced ET in an Au-TiO2 system is possible in spite of the fast energy relaxation. The simulation shows that the photogenerated plasmon is highly delocalized onto TiO2, and thus, it is shared by the electron donor and acceptor materials. In the 50% of the cases remaining after the instantaneous photogeneration of the charge-separated state, the electron injects into TiO2 on a sub-100 fs time scale by the nonadiabatic mechanism due to high density of acceptor states. The electron-phonon relaxation parallels the injection and is slower, resulting in a transient heating of the TiO2 surface by 40 K. Driven by entropy, the electron moves further into TiO2 bulk. If the electron remains trapped at the TiO2 surface, it recombines with the hole on a picosecond time scale. The obtained ET and recombination times are in excellent agreement with the experiment. The delocalized plasmon state observed in our study establishes a novel concept for plasmonic photosensitization of wide band gap semiconductors, leading to efficient conversion of photons to charge carriers and to hybrid materials with a wide

  14. Surface-sensitive conductivity measurement using a micro multi-point probe approach

    DEFF Research Database (Denmark)

    Perkins, Edward; Barreto, Lucas; Wells, Justin

    2013-01-01

    An instrument for microscale electrical transport measurements in ultra-high vacuum is presented. The setup is constructed around collinear lithographically-created multi-point probes with a contact spacing down to 500 nm. Most commonly, twelve-point probes are used. These probes are approached...... measurements with an equidistant four-point probe for a wide range of contact spacings. In this way, it is possible to distinguish between bulk-like and surface-like conduction. The paper describes the design of the instrument and the approach to data and error analysis. Application examples are given...

  15. Rhamnolipids elicit the same cytotoxic sensitivity between cancer cell and normal cell by reducing surface tension of culture medium.

    Science.gov (United States)

    Jiang, Lifang; Shen, Chong; Long, Xuwei; Zhang, Guoliang; Meng, Qin

    2014-12-01

    Biosurfactant rhamnolipids have been claimed to show biological activities of inhibiting the proliferation of cancer cells. In this study, the cytotoxicity of rhamnolipids was examined on four cancer cells (HepG2, Caco-2, Hela, MCF-7 cells) and two normal cells (HK-2 cell, primary hepatocyte). Interestingly, both cancer cells and normal cells exhibited similar sensitivities to the addition of rhamnolipids in culture medium, and the cytotoxicity was largely attenuated by the presence of fetal bovine serum (FBS) in culture medium. In correlation of the mono-/di-rhamnolipid cytotoxicity with the surface tension of culture medium, it was found that rhamnolipids triggered cytotoxicity whenever the surface tension of culture medium decreased below 41 mN/m irrespective of the FBS content in culture medium, cell line, or rhamnolipid congener. Similarly, each chemical surfactant (Tween-80, sodium dodecyl sulfate, and sodium dodecyl benzene sulfonate) could cause cytotoxicity on HepG2 cells whenever its addition made the surface tension under 41 mN/m in culture medium with or without the presence of FBS. It seems that rhamnolipids, like chemical surfactants, exhibited cytotoxicity by reducing the surface tension of culture medium rather than by changing its specific molecular structure, which had no selection on tumor cells. This study could offer helps to correct the misleading biological activity of rhamnolipids and to avoid the possible large wastes of time and expenses on developing the applications in antitumor drugs.

  16. Influence of Different Surface Modifications on the Photovoltaic Performance and Dark Current of Dye-Sensitized Solar Cells

    Institute of Scientific and Technical Information of China (English)

    XU Weiwei; DAI Songyuan; HU Linhua; ZHANG Changneng; XIAO Shangfeng; LUO Xiangdong; JING Weiping; WANG Kongjia

    2007-01-01

    The TiO2 nanoporous film photoelectrode, as a crucial component of dye-sensitized solar cells, has been investigated. The photovoltaic properties and the dark current were studied by two surface modification methods. One was to apply a compact layer between the conductive glass substrate and nanoporous TiO2 film. Another was to produce TiO2 nanoparticles among the microstructure by TiCU treatment. A suitable concentration and number of times for TiCU treatment were found in our experiment. The dark current is suppressed by surface modifications, leading to a significant improvement in the solar cells performance. An excessive concentration of TiCU will produce more surface states and introduce a larger dark current reversely. The dye is also regarded as a source of charge recombination in dark to some extent, due to an amount of surface protonations introduced by the interfacial link in the conductive glass substrate/dye interface and dye/TiO2 interface.

  17. Sensitivity of Horn of Africa Rainfall to Regional Sea Surface Temperature Forcing

    Directory of Open Access Journals (Sweden)

    Zewdu T. Segele

    2015-05-01

    Full Text Available The Abdus Salam International Center for Theoretical Physics (ICTP version 4.4 Regional Climate Model (RegCM4 is used to investigate the rainfall response to cooler/warmer sea surface temperature anomaly (SSTA forcing in the Indian and Atlantic Oceans. The effect of SSTA forcing in a specific ocean basin is identified by ensemble, averaging 10 individual simulations in which a constant or linearly zonally varying SSTA is prescribed in individual basins while specifying the 1971–2000 monthly varying climatological sea surface temperature (SST across the remaining model domain. The nonlinear rainfall response to SSTA amplitude also is investigated by separately specifying +1K, +2K, and +4K SSTA forcing in the Atlantic and Indian Oceans. The simulation results show that warm SSTs over the entire Indian Ocean produce drier conditions across the larger Blue Nile catchment, whereas warming ≥ +2K generates large positive rainfall anomalies exceeding 10 mm·day−1 over drought prone regions of Northeastern Ethiopia. However, the June–September rainy season tends to be wetter (drier when the SST warming (cooling is limited to either the Northern or Southern Indian Ocean. Wet rainy seasons generally are characterized by deepening of the monsoon trough, east of 40°E, intensification of the Mascarene high, strengthening of the Somali low level jet and the tropical easterly jet, enhanced zonal and meridional vertically integrated moisture fluxes, and steeply vertically decreasing moist static energy. The opposite conditions hold for dry monsoon seasons.

  18. Tactile surface classification for limbed robots using a pressure sensitive robot skin.

    Science.gov (United States)

    Shill, Jacob J; Collins, Emmanuel G; Coyle, Eric; Clark, Jonathan

    2015-02-02

    This paper describes an approach to terrain identification based on pressure images generated through direct surface contact using a robot skin constructed around a high-resolution pressure sensing array. Terrain signatures for classification are formulated from the magnitude frequency responses of the pressure images. The initial experimental results for statically obtained images show that the approach yields classification accuracies [Formula: see text]. The methodology is extended to accommodate the dynamic pressure images anticipated when a robot is walking or running. Experiments with a one-legged hopping robot yield similar identification accuracies [Formula: see text]. In addition, the accuracies are independent with respect to changing robot dynamics (i.e., when using different leg gaits). The paper further shows that the high-resolution capabilities of the sensor enables similarly textured surfaces to be distinguished. A correcting filter is developed to accommodate for failures or faults that inevitably occur within the sensing array with continued use. Experimental results show using the correcting filter can extend the effective operational lifespan of a high-resolution sensing array over 6x in the presence of sensor damage. The results presented suggest this methodology can be extended to autonomous field robots, providing a robot with crucial information about the environment that can be used to aid stable and efficient mobility over rough and varying terrains.

  19. Sensitivity of snow cover to horizontal resolution in a land surface model

    Science.gov (United States)

    Dutra, E.; Kotlarski, S.; Viterbo, P.; Balsamo, G.; Miranda, P. M. A.; Schär, C.

    2010-09-01

    Snow cover is a highly variable land surface condition that exerts a strong control on the heat and moisture budget of the overlying atmosphere. Modeling studies based on long integrations of global circulation models (GCM) are normally carried out at very low resolution (typically coarser than 100 km) due to their high computational demand. On local scales, snow cover plays an important socioeconomic role, ranging from water management applications to outdoor recreation. These latter applications vary in horizontal resolution from a few hundred meters to a few kilometers, where small scale topography, land cover and local circulation effects play a significant role. In this study our focus will be on horizontal scales ranging from typical GCM global climate modeling to high resolution global weather forecasts. In the land surface component of a GCM (land surface model - LSM), snow cover temporal and spatial variability is mainly determined by the overlying atmospheric conditions. However, once snowfall settles on the ground, the sub-grid scale variability associated with complex terrain and land cover variability (not resolved at the model resolution) is parameterized following simple physical and/or empirical relations. The present study intends to access the impact of horizontal resolution in the European Centre for Medium-Range Weather Forecasts (ECMWF) land surface model (HTESSEL). HTESSEL is forced by the ECMWF operational weather forecasts since March 2006 to December 2009 (runs in offline/stand-alone mode). The control run is carried out at the horizontal resolution of the forecasts at TL799 (gaussian reduced grid N400 -about 25 km). Two lower horizontal resolutions are then tested: TL255 (gaussian reduced grid - about 80 km, same as the ERA-Interim reanalysis), and TL95 (gaussian reduced grid N48 - about 200 km). The length of the simulations is rather small (only 46 months), however global meteorological forcing at 25 km can only be accessed through the

  20. Analytical modelling and experimental verification of the three-dimensional current distribution on the top surface of silicon solar cells operating under concentrated sunlight

    Energy Technology Data Exchange (ETDEWEB)

    Costagliola, Maurizio; Riccio, Michele; Irace, Andrea; Breglio, Gianluca; Daliento, Santolo [Department of Biomedical, Electronics and Telecommunications Engineering, University of Naples ' ' Federico II' ' , via Claudio 21, 80125 Naples (Italy)

    2011-03-15

    The approximation that the current is constant in any point of the emitter is not true for solar cells operating under concentrated sunlight. The transverse paths followed by photogenerated carriers to reach metal grid electrodes causes voltage drops leading to non-uniform distributed surface potential and a consequent reduction of the conversion efficiency. Moreover, concentrating lens often provide non-uniform light intensity thus worsening non-uniform current distribution. The correct design of surface geometry of the cell (metal grid, emitter depth, sheet resistance) should always take into account the above effects. Unfortunately a lack of reliable models still exists. In this paper we analytically solve the three-dimensional semiconductor equations with proper boundary conditions and taking into account, as source term, a distributed generation contribute. The reliability of the model has been tested by numerical simulations and experimentally verified with a lock-in thermography technique (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  1. Nanocrystalline BaSnO3 as an Alternative Gas Sensor Material: Surface Reactivity and High Sensitivity to SO2

    Directory of Open Access Journals (Sweden)

    Artem Marikutsa

    2015-09-01

    Full Text Available Nanocrystalline perovskite-type BaSnO3 was obtained via microwave-assisted hydrothermal route followed by annealing at variable temperature. The samples composition and microstructure were characterized. Particle size of 18–23 nm was unaffected by heat treatment at 275–700 °C. Materials DC-conduction was measured at variable temperature and oxygen concentration. Barium stannate exhibited n-type semiconductor behavior at 150–450 °C with activation energy being dependent on the materials annealing temperature. Predominant ionosorbed oxygen species types were estimated. They were shown to change from molecular to atomic species on increasing temperature. Comparative test of sensor response to various inorganic target gases was performed using nanocrystalline SnO2-based sensors as reference ones. Despite one order of magnitude smaller surface area, BaSnO3 displayed higher sensitivity to SO2 in comparison with SnO2. DRIFT spectroscopy revealed distinct interaction routes of the oxides surfaces with SO2. Barium-promoted sulfate formation favoring target molecules oxidation was found responsible for the increased BaSnO3 sensitivity to ppm-range concentrations of SO2 in air.

  2. Extremely sensitive sandwich assay of kanamycin using surface-enhanced Raman scattering of 2-mercaptobenzothiazole labeled gold@silver nanoparticles.

    Science.gov (United States)

    Zengin, Adem; Tamer, Ugur; Caykara, Tuncer

    2014-03-19

    Herein, we report the development of extremely sensitive sandwich assay of kanamycin using a combination of anti-kanamycin functionalized hybrid magnetic (Fe3O4) nanoparticles (MNPs) and 2-mercaptobenzothiazole labeled Au-core@Ag-shell nanoparticles as the recognition and surface-enhanced Raman scattering (SERS) substrate, respectively. The hybrid MNPs were first prepared via surface-mediated RAFT polymerization of N-acryloyl-L-glutamic acid in the presence of 2-(butylsulfanylcarbonylthiolsulfanyl) propionic acid-modified MNPs as a RAFT agent and then biofunctionalized with anti-kanamycin, which are both specific for kanamycin and can be collected via a simple magnet. After separating kanamycin from the sample matrix, they were sandwiched with the SERS substrate. According to our experimental results, the limit of detection (LOD) was determined to be 2pg mL(-1), this value being about 3-7 times more than sensitive than the LOD of previously reported results, which can be explained by the higher SERS activity of silver coated gold nanoparticles. The analysis time took less than 10min, including washing and optical detection steps. Furthermore, the sandwich assay was evaluated for investigating the kanamycin specificity on neomycin, gentamycin and streptomycin and detecting kanamycin in artificially contaminated milk.

  3. Improved Sensitization of Zinc Oxide Nanorods by Cadmium Telluride Quantum Dots through Charge Induced Hydrophilic Surface Generation

    Directory of Open Access Journals (Sweden)

    Karthik Laxman

    2014-01-01

    Full Text Available This paper reports on UV-mediated enhancement in the sensitization of semiconductor quantum dots (QDs on zinc oxide (ZnO nanorods, improving the charge transfer efficiency across the QD-ZnO interface. The improvement was primarily due to the reduction in the interfacial resistance achieved via the incorporation of UV light induced surface defects on zinc oxide nanorods. The photoinduced defects were characterized by XPS, FTIR, and water contact angle measurements, which demonstrated an increase in the surface defects (oxygen vacancies in the ZnO crystal, leading to an increase in the active sites available for the QD attachment. As a proof of concept, a model cadmium telluride (CdTe QD solar cell was fabricated using the defect engineered ZnO photoelectrodes, which showed ∼10% increase in photovoltage and ∼66% improvement in the photocurrent compared to the defect-free photoelectrodes. The improvement in the photocurrent was mainly attributed to the enhancement in the charge transfer efficiency across the defect rich QD-ZnO interface, which was indicated by the higher quenching of the CdTe QD photoluminescence upon sensitization.

  4. Surface acidity and solid-state compatibility of excipients with an acid-sensitive API: case study of atorvastatin calcium.

    Science.gov (United States)

    Govindarajan, Ramprakash; Landis, Margaret; Hancock, Bruno; Gatlin, Larry A; Suryanarayanan, Raj; Shalaev, Evgenyi Y

    2015-04-01

    The objectives of this study were to measure the apparent surface acidity of common excipients and to correlate the acidity with the chemical stability of an acid-sensitive active pharmaceutical ingredient (API) in binary API-excipient powder mixtures. The acidity of 26 solid excipients was determined by two methods, (i) by measuring the pH of their suspensions or solutions and (ii) the pH equivalent (pHeq) measured via ionization of probe molecules deposited on the surface of the excipients. The chemical stability of an API, atorvastatin calcium (AC), in mixtures with the excipients was evaluated by monitoring the appearance of an acid-induced degradant, atorvastatin lactone, under accelerated storage conditions. The extent of lactone formation in AC-excipient mixtures was presented as a function of either solution/suspension pH or pHeq. No lactone formation was observed in mixtures with excipients having pHeq > 6, while the lactone levels were pronounced (> 0.6% after 6 weeks at 50°C/20% RH) with excipients exhibiting pHeq 6, 3-6, and API, were identified based on pHeq measurements. The incompatibility prediction was confirmed in the chemical stability tests using AC as an example of an acid-sensitive API.

  5. Nuclear techniques in analytical chemistry

    CERN Document Server

    Moses, Alfred J; Gordon, L

    1964-01-01

    Nuclear Techniques in Analytical Chemistry discusses highly sensitive nuclear techniques that determine the micro- and macro-amounts or trace elements of materials. With the increasingly frequent demand for the chemical determination of trace amounts of elements in materials, the analytical chemist had to search for more sensitive methods of analysis. This book accustoms analytical chemists with nuclear techniques that possess the desired sensitivity and applicability at trace levels. The topics covered include safe handling of radioactivity; measurement of natural radioactivity; and neutron a

  6. Real-Time Characterization of Electrospun PVP Nanofibers as Sensitive Layer of a Surface Acoustic Wave Device for Gas Detection

    Directory of Open Access Journals (Sweden)

    D. Matatagui

    2014-01-01

    Full Text Available The goal of this work has been to study the polyvinylpyrrolidone (PVP fibers deposited by means of the electrospinning technique for using as sensitive layer in surface acoustic wave (SAW sensors to detect volatile organic compounds (VOCs. The electrospinning process of the fibers has been monitored and RF characterized in real time, and it has been shown that the diameters of the fibers depend mainly on two variables: the applied voltage and the distance between the needle and the collector, since all the electrospun fibers have been characterized by a scanning electron microscopy (SEM. Real-time measurement during the fiber coating process has shown that the depth of penetration of mechanical perturbation in the fiber layer has a limit. It has been demonstrated that once this saturation has been reached, the increase of the thickness of the fibers coating does not improve the sensitivity of the sensor. Finally, the parameters used to deposit the electrospun fibers of smaller diameters have been used to deposit fibers on a SAW device to obtain a sensor to measure different concentrations of toluene at room temperature. The present sensor exhibited excellent sensitivity, good linearity and repeatability, and high and fast response to toluene at room temperature.

  7. Surface solar radiation and hydrological cycle in 20th century China: sensitivity studies with ECHAM5-HAM

    Science.gov (United States)

    Folini, D.; Wild, M.

    2012-04-01

    The world, and China in particular, has seen a tremendous population growth and industrialization in the 20th century. These changes were accompanied, among others, by a substantial increase in aerosol emission. To learn more about associated consequences for the climate system we have carried out a comparatively large set of transient sensitivity studies with the global atmosphere only climate model ECHAM5-HAM, using aerosol emission data from NIES (National Institute of Environmental Studies, Japan) and prescribed, observation based sea surface temperatures (SSTs) from the Hadley Center. The sensitivity studies cover the period from 1870 to 2005 and comprise ensembles of simulations (up to 13 members per ensemble), which allow to address the role of different aerosol species, greenhouse gases, and prescribed sea surface temperatures. Here we analyze these simulation data with particular focus on surface solar radiation, temperature, and the hydrological cycle in China. Physical mechanisms able to explain the results will be discussed. We generally find the strongest effects in the east of the country, where urbanization and industrialization is strongest and emissions increased most. The decrease of surface solar radiation (SSR) under clear sky conditions reaches up to around -8 W / m2 per decade from 1950 to 1990. Comparable values are found for all sky conditions. Dimming ceases in the second half of the 1990s, when we even see a renewed increase in SSR in some regions. Overall, these findings are in line with observation based estimates. Modeled surface temperatures reflect the decrease in SSR but carry also a substantial SST signature. After remaining roughly constant from 1870 to 1900, we find modeled surface temperatures to increase by about 1 degree Celsius till 1950, then decrease again by -0.2 to -1.2 degree Celsius till 1990, before a renewed increase sets in. Precipitation decreases in our model results from 1950 to 2000 by up to 10% or 150 mm per year

  8. Sensitivity of the Greenland Ice Sheet to Pliocene sea surface temperatures

    Science.gov (United States)

    Hill, Daniel J.; Dolan, Aisling M.; Haywood, Alan M.; Hunter, Stephen J.; Stoll, Danielle K.

    2010-01-01

    The history of theGrIS (Greenland Ice Sheet), particularly in warm climates of the pre-Quaternary, is poorly known. IRD (ice-rafted debris) records suggest that the ice sheet has existed, at least transiently, since theMiocene and potentially since as long ago as the Eocene. As melting of the GrIS is a key uncertainty in future predictions of climate and sea-level, understanding its behaviour and role within the climate system during pastwarm periods could provide important constraints. The Pliocene has been identified as a key period for understanding warmer than modern climates. Detailed micropalaeontological analyses of the mid-Piacenzian Warm Period (3.264-3.025 Ma) have produced a series of SST (sea-surface temperature) reconstructions (PRISM2-AVE, PRISM2-MAX, PRISM2-MIN and

  9. On the sensitivity of Land Surface Temperature estimates in arid irrigated lands using MODTRAN

    KAUST Repository

    Rosas, Jorge

    2015-11-29

    Land surface temperature (LST) derived from thermal infrared (TIR) satellite data has been reliably used as a remote indicator of evapotranspiration (ET) and surface moisture status. However, in order to retrieve the ET with an accuracy approaching 10%, LST should be retrieved to within 1 ◦C or better, disregarding other elements of uncertainty. The removal of atmospheric effects is key towards achieving a precise estimation of LST and it requires detailed information on water vapor. The Thermal Infrared Sensor (TIRS) onboard Landsat 8 captures data in two long wave thermal bands with 100-meter resolution. However, the US Geological Survey has reported a calibration problem of TIRS bands caused by stray light, resulting in a higher bias in one of its two bands (4% in band 11, 2% in band 10). Therefore, split-window algorithms for the estimation of LST might not be reliable. Our work will focus o