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Sample records for admittance characterization based

  1. Characterizing the eardrum admittance: Comparisons of tympanometry and reflectance

    NASA Astrophysics Data System (ADS)

    Robinson, Sarah; Thompson, Suzanne; Allen, Jont B.

    2015-12-01

    The residual ear canal (REC) between the probe and tympanic membrane (TM) is a significant source of non-pathological variability for acoustic measurements made in the ear canal. Tympanometry and reflectance, which seek to characterize the middle ear based on the TM admittance, must account for unknown REC dimensions. In tympanometry, the REC volume and 226 Hz TM admittance are estimated by varying the canal static pressure. Using a reflectance parametrization developed by the authors, typical assumptions for removing the REC effect are extended, and methods to estimate the REC volume and TM admittance are presented and compared to tympanometry. Results of this method are shown for reflectance measurements of human ears with varying static middle ear pressures (MEPs). The data show that the 226 Hz TM compliance is non-zero at tympanometric pressure extremes, and that acoustic parameters of the middle ear have highly variable, nonlinear dependence on the MEP level.

  2. A creatinine biosensor based on admittance measurement

    NASA Astrophysics Data System (ADS)

    Ching, Congo Tak-Shing; Sun, Tai-Ping; Jheng, Deng-Yun; Tsai, Hou-Wei; Shieh, Hsiu-Li

    2015-08-01

    Regular check of blood creatinine level is very important as it is a measurement of renal function. Therefore, the objective of this study is to develop a simple and reliable creatinine biosensor based on admittance measurement for precise determination of creatinine. The creatinine biosensor was fabricated with creatinine deiminase immobilized on screen-printed carbon electrodes. Admittance measurement at a specific frequency ranges (22.80 - 84.71 Hz) showed that the biosensor has an excellent linear (r2 > 0.95) response range (50 - 250 uM), which covers the normal physiological and pathological ranges of blood creatinine levels. Intraclass correlation coefficient (ICC) showed that the biosensor has excellent reliability and validity (ICC = 0.98). In conclusion, a simple and reliable creatinine biosensor was developed and it is capable of precisely determining blood creatinine levels in both the normal physiological and pathological ranges.

  3. Analytical admittance characterization of high mobility channel

    SciTech Connect

    Mammeri, A. M.; Mahi, F. Z.; Varani, L.

    2015-03-30

    In this contribution, we investigate the small-signal admittance of the high electron mobility transistors field-effect channels under a continuation branching of the current between channel and gate by using an analytical model. The analytical approach takes into account the linearization of the 2D Poisson equation and the drift current along the channel. The analytical equations discuss the frequency dependence of the admittance at source and drain terminals on the geometrical transistor parameters.

  4. Electrical admittance of piezoelectric parallelepipeds: application to tensorial characterization of piezoceramics

    NASA Astrophysics Data System (ADS)

    Diallo, O.; Clezio, E. Le; Delaunay, T.; Bavencoffe, M.; Feuillard, G.

    2014-01-01

    This work deals with the characterization of functional properties, including determination of mechanical and electrical losses, of piezoelectric materials using only one sample and one measurement. First, the natural resonant frequencies of a piezoelectric parallelepiped are calculated and the electrical admittance is determined from calculations of the charge quantity on both electrodes of the parallelepiped. A first validation of the model is performed using a comparison with Mason's model. Results are reported for a PMN-34.5PT ceramic cube and a good agreement is found between experimental admittance measurements and their modeling. The functional properties of the PMN-34.5PT are then extracted.

  5. Electrical admittance of piezoelectric parallelepipeds: application to tensorial characterization of piezoceramics

    SciTech Connect

    Diallo, O.; Bavencoffe, M.; Feuillard, G.; Clezio, E. Le; Delaunay, T.

    2014-01-15

    This work deals with the characterization of functional properties, including determination of mechanical and electrical losses, of piezoelectric materials using only one sample and one measurement. First, the natural resonant frequencies of a piezoelectric parallelepiped are calculated and the electrical admittance is determined from calculations of the charge quantity on both electrodes of the parallelepiped. A first validation of the model is performed using a comparison with Mason's model. Results are reported for a PMN-34.5PT ceramic cube and a good agreement is found between experimental admittance measurements and their modeling. The functional properties of the PMN-34.5PT are then extracted.

  6. Feasibility of anomaly detection and characterization using trans-admittance mammography with 60 × 60 electrode array

    NASA Astrophysics Data System (ADS)

    Zhao, Mingkang; Wi, Hun; Lee, Eun Jung; Woo, Eung Je; In Oh, Tong

    2014-10-01

    Electrical impedance imaging has the potential to detect an early stage of breast cancer due to higher admittivity values compared with those of normal breast tissues. The tumor size and extent of axillary lymph node involvement are important parameters to evaluate the breast cancer survival rate. Additionally, the anomaly characterization is required to distinguish a malignant tumor from a benign tumor. In order to overcome the limitation of breast cancer detection using impedance measurement probes, we developed the high density trans-admittance mammography (TAM) system with 60 × 60 electrode array and produced trans-admittance maps obtained at several frequency pairs. We applied the anomaly detection algorithm to the high density TAM system for estimating the volume and position of breast tumor. We tested four different sizes of anomaly with three different conductivity contrasts at four different depths. From multifrequency trans-admittance maps, we can readily observe the transversal position and estimate its volume and depth. Specially, the depth estimated values were obtained accurately, which were independent to the size and conductivity contrast when applying the new formula using Laplacian of trans-admittance map. The volume estimation was dependent on the conductivity contrast between anomaly and background in the breast phantom. We characterized two testing anomalies using frequency difference trans-admittance data to eliminate the dependency of anomaly position and size. We confirmed the anomaly detection and characterization algorithm with the high density TAM system on bovine breast tissue. Both results showed the feasibility of detecting the size and position of anomaly and tissue characterization for screening the breast cancer.

  7. Dynamic characterization of partially saturated engineered porous media and gas diffusion layers using hydraulic admittance

    NASA Astrophysics Data System (ADS)

    Cheung, Perry; Fairweather, Joseph D.; Schwartz, Daniel T.

    2012-09-01

    Simple laboratory methods for determining liquid water distribution in polymer electrolyte membrane fuel cell gas diffusion layers (GDLs) are needed to engineer better GDL materials. Capillary pressure vs. liquid saturation measurements are attractive, but lack the ability to probe the hydraulic interconnectivity and distribution within the pore structure. Hydraulic admittance measurements of simple capillary bundles have recently been shown to nicely measure characteristics of the free-interfaces and hydraulic path. Here we examine the use of hydraulic admittance with a succession of increasingly complex porous media, starting with a laser-drilled sample with 154 asymmetric pores and progress to the behavior of Toray TGP-H090 carbon papers. The asymmetric laser-drilled sample clearly shows hydraulic admittance measurements are sensitive to sample orientation, especially when examined as a function of saturation state. Finite element modeling of the hydraulic admittance is consistent with experimental measurements. The hydraulic admittance spectra from GDL samples are complex, so we examine trends in the spectra as a function of wet proofing (0% and 40% Teflon loadings) as well as saturation state of the GDL. The presence of clear peaks in the admittance spectra for both GDL samples suggests a few pore types are largely responsible for transporting liquid water.

  8. Acoustic-Liner Admittance in a Duct

    NASA Technical Reports Server (NTRS)

    Watson, W. R.

    1986-01-01

    Method calculates admittance from easily obtainable values. New method for calculating acoustic-liner admittance in rectangular duct with grazing flow based on finite-element discretization of acoustic field and reposing of unknown admittance value as linear eigenvalue problem on admittance value. Problem solved by Gaussian elimination. Unlike existing methods, present method extendable to mean flows with two-dimensional boundary layers as well. In presence of shear, results of method compared well with results of Runge-Kutta integration technique.

  9. Admittance Investigation of MIS Structures with HgTe-Based Single Quantum Wells

    NASA Astrophysics Data System (ADS)

    Izhnin, Ihor I.; Nesmelov, Sergey N.; Dzyadukh, Stanislav M.; Voitsekhovskii, Alexander V.; Gorn, Dmitry I.; Dvoretsky, Sergey A.; Mikhailov, Nikolaj N.

    2016-02-01

    This work presents results of the investigation of admittance of metal-insulator-semiconductor structure based on Hg1 - x Cd x Te grown by molecular beam epitaxy. The structure contains a single quantum well Hg0.35Cd0.65Te/HgTe/Hg0.35Cd0.65Te with thickness of 5.6 nm in the sub-surface layer of the semiconductor. Both the conductance-voltage and capacitance-voltage characteristics show strong oscillations when the metal-insulator-semiconductor (MIS) structure with a single quantum well based on HgTe is biased into the strong inversion mode. Also, oscillations on the voltage dependencies of differential resistance of the space charge region were observed. These oscillations were related to the recharging of quantum levels in HgTe.

  10. Admittance Investigation of MIS Structures with HgTe-Based Single Quantum Wells.

    PubMed

    Izhnin, Ihor I; Nesmelov, Sergey N; Dzyadukh, Stanislav M; Voitsekhovskii, Alexander V; Gorn, Dmitry I; Dvoretsky, Sergey A; Mikhailov, Nikolaj N

    2016-12-01

    This work presents results of the investigation of admittance of metal-insulator-semiconductor structure based on Hg1 - x Cd x Te grown by molecular beam epitaxy. The structure contains a single quantum well Hg0.35Cd0.65Te/HgTe/Hg0.35Cd0.65Te with thickness of 5.6 nm in the sub-surface layer of the semiconductor. Both the conductance-voltage and capacitance-voltage characteristics show strong oscillations when the metal-insulator-semiconductor (MIS) structure with a single quantum well based on HgTe is biased into the strong inversion mode. Also, oscillations on the voltage dependencies of differential resistance of the space charge region were observed. These oscillations were related to the recharging of quantum levels in HgTe. PMID:26831691

  11. Sixteen-Year Change in Acoustic-Admittance Measures among Older Adults: Data from a Population-Based Study

    ERIC Educational Resources Information Center

    Nondahl, David M.; Cruickshanks, Karen J.; Wiley, Terry L.; Tweed, Ted S.; Dalton, Dayna S.

    2013-01-01

    Purpose: The primary purpose of this study was to measure the 16-year change in peak compensated static acoustic admittance (Peak Y[subscript tm]) in a population-based cohort of older adults, and to determine whether age was associated with any observed change in Peak Y[subscript tm]. Other tympanometric measures also were taken and analyzed.…

  12. An Investigation into the Admittance of MIS-Structures Based on MBE HgCdTe with Quantum Wells

    NASA Astrophysics Data System (ADS)

    Dzyadukh, S. M.; Voitsekhovskii, A. V.; Nesmelov, S. N.; Dvoretskii, S. A.; N. Mikhailov, N.; Gorn, D. I.

    2013-12-01

    The results of investigations into the complex admittance of the MIS-structures based on heteroepitaxial MBE Hg1- x Cd x Te with quantum wells (QW) in the test-signal frequency range 1 kHz - 2 МHz at temperatures 8-300 K are reported. The thickness of single HgTe QWs was 5.6 and 7.1 nm, the content in the 35-nm thick barrier layers - 0.65 and 0.62, respectively.

  13. Multi-port admittance model for quantifying the scattering response of loaded plasmonic nanorod antennas.

    PubMed

    Panaretos, Anastasios H; Werner, Douglas H

    2015-02-23

    In this paper we demonstrate the feasibility of using multiport network theory to describe the admittance properties of a longitudinally loaded plasmonic nanorod antenna. Our analysis reveals that if the appropriate terminal ports are defined across the nanorod geometry then the corresponding voltage and current quantities can be probed and thus it becomes feasible to extract the admittance matrix of the structure. Furthermore, it is demonstrated that by utilizing cylindrical dielectric waveguide theory, closed form expressions can be derived that uniquely characterize the loading material in terms of its admittance. The combination of the admittance matrix information along with the load admittance expressions provides an effective methodology for computing the nanorod's input admittance/impedance for arbitrary loading scenarios. This is important because the admittance resonances are associated with the structure's scattering peaks which are excited by a plane wave polarized parallel to its long dimension. Subsequently, the proposed approach provides a fast and computationally efficient circuit-based methodology to predict and custom engineer the scattering properties of a loaded plasmonic nanorod without having to rely on repetitive lengthy full wave simulations. PMID:25836483

  14. Applications of Admittance Spectroscopy in Photovoltaic Devices Beyond Majority Carrier Trapping Defects: Preprint

    SciTech Connect

    Li, J. V.; Crandall, R. S.; Repins, I. L.; Nardes, A. M.; Levi, D. H.; Sulima, O.

    2011-07-01

    Admittance spectroscopy is commonly used to characterize majority-carrier trapping defects. In today's practical photovoltaic devices, however, a number of other physical mechanisms may contribute to the admittance measurement and interfere with the data interpretation. Such challenges arise due to the violation of basic assumptions of conventional admittance spectroscopy such as single-junction, ohmic contact, highly conductive absorbers, and measurement in reverse bias. We exploit such violations to devise admittance spectroscopy-based methods for studying the respective origins of 'interference': majority-carrier mobility, non-ohmic contact potential barrier, minority-carrier inversion at hetero-interface, and minority-carrier lifetime in a device environment. These methods are applied to a variety of photovoltaic technologies: CdTe, Cu(In,Ga)Se2, Si HIT cells, and organic photovoltaic materials.

  15. Admittance spectroscopy of solar cells based on GaPNAs layers

    SciTech Connect

    Baranov, A. I. Gudovskikh, A. S.; Zelentsov, K. S.; Nikitina, E. V.; Egorov, A. Yu.

    2015-04-15

    Admittance spectroscopy is used to study defect levels in the layers of a GaPNAs quaternary solid solution. Centers with an activation energy of 0.22 eV and a capture cross section of ∼2.4 × 10{sup −15} cm{sup 2} are found in doped n-GaPNAs layers grown on GaP substrates. These centers correspond to already known Si{sub Ga} + V{sub P} defects in n-GaP; annealing decreases their concentration by several times. A level with an activation energy of 0.23–0.24 eV and capture cross section of ∼9.0 × 10{sup −20} cm{sup 2} is found in undoped GaPNAs layers grown on Si and GaP substrates. The concentration of these centers substantially decreases upon annealing, and, at annealing temperatures exceeding 600°C, there is absolutely no response from these defects. For undoped GaPNAs layers grown on GaP substrates, a level with an activation energy of 0.18 eV and capture cross section of ∼1.1 × 10{sup −16} cm{sup 2} is also found. The concentration of these centers remains unchanged upon annealing.

  16. Performance analysis of a plasmonic sensor based on gold nanoparticle film in infrared light using the admittance loci method

    NASA Astrophysics Data System (ADS)

    Brahmachari, Kaushik; Ray, Mina

    2015-02-01

    A theoretical design of surface plasmon resonance (SPR) structure operating in attenuated total reflection (ATR) mode and comprising of silicon or chalcogenide (2S2G) prism material coated with gold film having different nanoparticle sizes has been reported along with some interesting performance related simulation results at the operating wavelength of 1200 nm in infrared. The admittance loci based technique has been employed for the appropriate choice of the metal layer thickness. The sensitivity and other performance parameters of the structure based on the choice of the high index prism material and correct gold nanoparticle size have also been presented. In comparison to other conventional prism based plasmonic structures, the proposed model provides the extra degree of freedom, i.e., variations of nanoparticle size in addition to the variation in layer thickness and the use of different high index prism materials like silicon, 2S2G materials, etc. Moreover, the width of the SPR curve can be controlled by using different high index prism materials as well as by changing gold nanoparticle size. Higher sensitivity can be achieved with 2S2G while higher detection accuracy is provided by silicon as prism material.

  17. Tevatron admittance measurement

    SciTech Connect

    Zhang, X.L.; Shiltsev, V.; Tan, C.Y.; /Fermilab

    2005-05-01

    We measured the Tevatron beam admittance by the means of exciting the beam with noise and causing emittance growth. The noise power was about 3W with a bandwidth of 100Hz and centered either in the horizontal betatron frequency or vertical betatron frequency. We were able to controllably blow the beam emittance up quickly. From the point where the beam emittance stopped growing, we measured the beam acceptance of the Tevatron.

  18. Analytical Method for Selecting a Rectification Technique for a Piezoelectric Generator based on Admittance Measurement

    NASA Astrophysics Data System (ADS)

    Mateu, Loreto; Zessin, Henrik; Spies, Peter

    2013-12-01

    AC-DC converters employed for harvesting power from piezoelectric transducers can be divided into linear (i.e. diode bridge) and non-linear (i.e. synchronized switch harvesting on inductor, SSHI). This paper presents an analytical technique based on the measurement of the impedance circle of the piezoelectric element to determine whether either diode bridge or SSHI converter harvests more of the available power at the piezoelectric element.

  19. [Development of a handy-type monitoring system for cardiovascular haemodynamic functions based on the volume-compensation and electrical admittance method].

    PubMed

    Song, Yi-lin; Gao, Shu-mei; Ikarashi, Akira; Yamakoshi, Ken-ichi

    2009-03-01

    A handy-type monitoring system for cardiovascular haemodynamic functions based on the volume-compensation and electrical admittance method is developed. In this system, the inconvenient and discomfort due to cuff occlusion of the biological segment for BP measurement is improved by developing a new device using a local pressurization method, the stability for the physiological information detection is improved by developing a new detecting system, and the noise during detection using the system is greatly reduced by using a newly developed nozzle-flapper type electro-pneumatic converter. Also, for electrical admittance cardiography to estimate CO, the applicability of a two-compartment coaxial cylindrical model and the optimal position of a spot-electrode array that is used to replace the conventional band-electrode are discussed in this research. Experimental result shows that the monitoring system should satisfy non-invasive BP and CO measurement on beat by beat, and the comfort of measurement is significantly improved. PMID:19771888

  20. Accurate determination of interface trap state parameters by admittance spectroscopy in the presence of a Schottky barrier contact: Application to ZnO-based solar cells

    NASA Astrophysics Data System (ADS)

    Marin, Andrew T.; Musselman, Kevin P.; MacManus-Driscoll, Judith L.

    2013-04-01

    This work shows that when a Schottky barrier is present in a photovoltaic device, such as in a device with an ITO/ZnO contact, equivalent circuit analysis must be performed with admittance spectroscopy to accurately determine the pn junction interface recombination parameters (i.e., capture cross section and density of trap states). Without equivalent circuit analysis, a Schottky barrier can produce an error of ˜4-orders of magnitude in the capture cross section and ˜50% error in the measured density of trap states. Using a solution processed ZnO/Cu2O photovoltaic test system, we apply our analysis to clearly separate the contributions of interface states at the pn junction from the Schottky barrier at the ITO/ZnO contact so that the interface state recombination parameters can be accurately characterized. This work is widely applicable to the multitude of photovoltaic devices, which use ZnO adjacent to ITO.

  1. Fibre optic sensors for load-displacement measurements and comparisons to piezo sensor based electromechanical admittance signatures

    NASA Astrophysics Data System (ADS)

    Maheshwari, Muneesh; Annamdas, Venu Gopal Madhav; Pang, John H. L.; Tjin, Swee Chuan; Asundi, Anand

    2015-04-01

    Structural health monitoring techniques using smart materials are on rise to meet the ever ending demand due to increased construction and manufacturing activities worldwide. The civil-structural components such as slabs, beams and columns and aero-components such as wings are constantly subjected to some or the other forms of external loading. This article thus focuses on condition monitoring due to loading/unloading cycle for a simply supported aluminum beam using multiple smart materials. On the specimen, fibre optic polarimetric sensor (FOPS) and fibre Bragg grating (FBG) sensors were glued. Piezoelectric wafer active sensor (PWAS) was also bonded at the centre of the specimen. FOPS and FBG provided the global and local strain measurements respectively whereas, PWAS predicted boundary condition variations by electromechanical admittance signatures. Thus these multiple smart materials together successfully assessed the condition of structure for loading and unloading tests.

  2. Anomaly depth detection in trans-admittance mammography: a formula independent of anomaly size or admittivity contrast

    NASA Astrophysics Data System (ADS)

    Zhang, Tingting; Lee, Eunjung; Seo, Jin Keun

    2014-04-01

    Trans-admittance mammography (TAM) is a bioimpedance technique for breast cancer detection. It is based on the comparison of tissue conductivity: cancerous tissue is identified by its higher conductivity in comparison with the surrounding normal tissue. In TAM, the breast is compressed between two electrical plates (in a similar architecture to x-ray mammography). The bottom plate has many sensing point electrodes that provide two-dimensional images (trans-admittance maps) that are induced by voltage differences between the two plates. Multi-frequency admittance data (Neumann data) are measured over the range 50 Hz-500 kHz. TAM aims to determine the location and size of any anomaly from the multi-frequency admittance data. Various anomaly detection algorithms can be used to process TAM data to determine the transverse positions of anomalies. However, existing methods cannot reliably determine the depth or size of an anomaly. Breast cancer detection using TAM would be improved if the depth or size of an anomaly could also be estimated, properties that are independent of the admittivity contrast. A formula is proposed here that can estimate the depth of an anomaly independent of its size and the admittivity contrast. This depth estimation can also be used to derive an estimation of the size of the anomaly. The proposed estimations are verified rigorously under a simplified model. Numerical simulation shows that the proposed method also works well in general settings.

  3. Computer code for the prediction of nozzle admittance

    NASA Technical Reports Server (NTRS)

    Nguyen, Thong V.

    1988-01-01

    A procedure which can accurately characterize injector designs for large thrust (0.5 to 1.5 million pounds), high pressure (500 to 3000 psia) LOX/hydrocarbon engines is currently under development. In this procedure, a rectangular cross-sectional combustion chamber is to be used to simulate the lower traverse frequency modes of the large scale chamber. The chamber will be sized so that the first width mode of the rectangular chamber corresponds to the first tangential mode of the full-scale chamber. Test data to be obtained from the rectangular chamber will be used to assess the full scale engine stability. This requires the development of combustion stability models for rectangular chambers. As part of the combustion stability model development, a computer code, NOAD based on existing theory was developed to calculate the nozzle admittances for both rectangular and axisymmetric nozzles. This code is detailed.

  4. Online Stability in Human-Robot Cooperation with Admittance Control.

    PubMed

    Dimeas, Fotios; Aspragathos, Nikos

    2016-01-01

    In the design of a compliant admittance controller for physical human-robot interaction, it is necessary to ensure stable and effective cooperation. The stability of the admittance controller is mainly threatened by a stiff environment. Many methods that guarantee stability in arbitrary environments, impose conservative control gains that limit the effectiveness of the cooperation. Inspired by previous work in frequency domain stability observers, a method is proposed in this paper to detect unstable behavior and stabilize the robot with online adaptation of the admittance control gains. The introduced instability index is based on frequency domain analysis, which very quickly detects unstable behavior by monitoring high frequency oscillation in the force signal. To treat the instability, an adaptation scheme of the admittance parameters is proposed, that relaxes conservative gains and improves the cooperation by considering the effect of variable admittance on the operators' effort. We investigate two human-robot co-manipulation tasks; cooperation within a zero stiffness environment and cooperation in contact with a stiff double-wall virtual environment. The proposed methods are validated experimentally with a number of subjects in cooperation with an LWR manipulator. PMID:26780819

  5. Improved multimodal admittance method in varying cross section waveguides.

    PubMed

    Maurel, Agnès; Mercier, Jean-François; Pagneux, Vincent

    2014-04-01

    An improved version of the multimodal admittance method in acoustic waveguides with varying cross sections is presented. This method aims at a better convergence with respect to the number of transverse modes that are taken into account. It is based on an enriched modal expansion of the pressure: the N first modes are the local transverse modes and a supplementary (N+1)th mode, called boundary mode, is a well-chosen transverse function orthogonal to the N first modes. This expansion leads to the classical form of the coupled mode equations where the component of the boundary mode is of evanescent character. Under this form, the multimodal admittance method based on the Riccati equation on the admittance matrix (the Dirichlet-to-Neumann operator) is straightforwardly implemented. With this supplementary mode, in addition to the improvement of the convergence of the pressure field, results show a superconvergence of the scattered field outside of the varying cross sections region. PMID:24711716

  6. Peculiarities of Determining the Dopant Concentration in the Near-Surface Layer of a Semiconductor by Measuring the Admittance of MIS Structures Based on P-Hg0.78Cd0.22Te Grown by Molecular Beam Epitaxy

    NASA Astrophysics Data System (ADS)

    Voitsekhovskii, A. V.; Nesmelov, S. N.; Dzyadukh, S. M.

    2016-06-01

    Peculiarities of determining the concentration and distribution profile of dopant in the near-surface layer of a semiconductor by measuring the admittance of MIS structures based on p-Hg0.78Cd0.22Te grown by molecular beam epitaxy are studied. A technique is proposed for the determining the concentration of dopant based on the measurement of the admittance of MIS structures in the frequency range of 50 kHz - 1 MHz. It is shown that in this frequency range, the capacitance-voltage characteristics of MIS structures based on p-Hg0.78Cd0.22Te with a near-surface graded-gap layer have a high- frequency behavior with respect to the recharge time of surface states located near the Fermi level of intrinsic semiconductor. The distribution profile of dopant in the nearsurface layer of the semiconductor is calculated. It is shown that in p-Hg0.78Cd0.22Te with a near-surface graded-gap layer, the dopant concentration has the lowest value near the interface with the insulator.

  7. Simultaneous reconstruction of permittivity and conductivity using multi-frequency admittance measurement in electrical capacitance tomography

    NASA Astrophysics Data System (ADS)

    Zhang, Maomao; Soleimani, Manuchehr

    2016-02-01

    Electrical capacitance tomography (ECT) is an imaging method mainly capable of reconstructing dielectric permittivity. Generally, the reactance part of complex admittance is measured in a selected frequency. This paper presents for the first time an in depth and systematic analysis of complex admittance data for simultaneous reconstruction of both electrical conductivity and dielectric permittivity. A complex-valued forward model, Jacobian matrix and inverse solution are developed in the time harmonic excitation mode to allow for multi-frequency measurements. Realistic noise models are used to evaluate the performance of complex admittance ECT in a range of excitation frequencies. This paper demonstrates far greater potential for ECT as a versatile imaging tool through novel analysis of complex admittance imaging using a dual conductivity permittivity inversion method. The paper demonstrates that various classes of contactless capacitance based measurement devices can be analysed through complex multi-frequency ECT.

  8. Special Features of Admittance in Mis Structures Based on Graded-Gap MBE n-Hg1- x Cd x Te ( x = 0.31-0.32) in a Temperature Range OF 8-300 K

    NASA Astrophysics Data System (ADS)

    Voitsekhovskii, A. V.; Nesmelov, S. N.; Dzyadukh, S. M.; Vasil'ev, V. V.; Varavin, V. S.; Dvoretskii, S. A.; Mikhailov, N. N.; Kuz'min, V. D.; Remesnik, V. G.

    2014-09-01

    Admittance of MIS structures based on graded-gap n-Hg1- х Cd х Te ( x = 0.31-0.32) grown by molecular beam epitaxy (MBE) is investigated in a wide temperature range (8-300 K). It is shown that the temperature and frequency dependences of the differential resistance of space charge region for structures with a graded-gap layer are qualitatively similar to those for structures without a graded-gap layer. It is found that for MIS structures based on MBE n-Hg1- х Cd х Te ( x = 0.31-0.32), regardless of the presence of a graded-gap layer, the differential resistance of space charge region is limited by the processes of Shockley-Read generation in the temperature range of 25-100 K.

  9. Increasing Immunization Compliance by Reducing Provisional Admittance.

    PubMed

    Davis, Wendy S; Varni, Susan E; Barry, Sara E; Frankowski, Barbara L; Harder, Valerie S

    2016-08-01

    Students in Vermont with incomplete or undocumented immunization status are provisionally admitted to schools and historically had a calendar year to resolve their immunization status. The process of resolving these students' immunization status was challenging for school nurses. We conducted a school-based quality improvement effort to increase student compliance with Vermont immunization regulations using a collaborative learning approach with public health school liaisons and school nurses from public schools to reduce provisional admittance in 2011-2012. Strategies included using a tracking system, accessing the immunization registry, promoting immunization importance, tracking immunization plans, and working with medical homes to update records. Participating school nurses observed decreases in the number of provisionally admitted students, although this reduction was not significantly different than matched comparison schools. We also found the number of provisionally admitted students fluctuated throughout the year and resolving the immunization status of New Americans and exchange students required special attention. Our approach supports the coordinated school health model and demonstrates the critical role school nurses play in improving population health outcomes. PMID:26699951

  10. Characterization of interface defects in ALD Al2O3/p-GaSb MOS capacitors using admittance measurements in range from kHz to GHz

    NASA Astrophysics Data System (ADS)

    Gu, Siyuan; Min, Jie; Taur, Yuan; Asbeck, Peter M.

    2016-04-01

    Atomic layer deposited (ALD) Al2O3/p-type GaSb Metal-Oxide-Semiconductor (MOS) capacitors are studied with capacitance-voltage (C-V) and conductance-voltage (G-V) measurements using AC signal frequencies covering the range from kHz to GHz. The potential and limitations of the measurements at GHz frequencies for oxide and interface defect characterization are described. The effect of bulk oxide traps in communication with the GaSb valence band via hole tunneling is highlighted. Modeling indicates that the C-V and G-V frequency dispersions observed in the accumulation, flat-band and depletion regions of the Al2O3/p-GaSb MOS capacitors are due to combined contributions of bulk-oxide traps and interface traps.

  11. Structures that Contribute to Middle-Ear Admittance in Chinchilla

    PubMed Central

    Rosowski, John J.; Ravicz, Michael E.; Songer, Jocelyn E.

    2009-01-01

    We describe measurements of middle-ear input admittance in chinchillas (Chinchilla lanigera) before and after various manipulations that define the contributions of different middle-ear components to function. The chinchilla’s middle-ear air spaces have a large effect on the low-frequency compliance of the middle ear, and removing the influences of these spaces reveals a highly admittant tympanic membrane and ossicular chain. Measurements of the admittance of the air spaces reveal that the high-degree of segmentation of these spaces has only a small effect on the admittance. Draining the cochlea further increases the middle-ear admittance at low frequencies and removes a low-frequency (less than 300 Hz) level dependence in the admittance. Spontaneous or sound-driven contractions of the middle-ear muscles in deeply anesthetized animals were associated with significant changes in middle-ear admittance. PMID:16944166

  12. Influence of composition of the near-surface graded-gap layer on the admittance of metal-insulator-semiconductor structures based on graded-gap MBE n-Hg1-xCdxTe in wide temperature range

    NASA Astrophysics Data System (ADS)

    Voitsekhovskii, A. V.; Nesmelov, S. N.; Dzyadukh, S. M.

    2014-12-01

    Influence of the CdTe content in a near-surface graded-gap layer on the admittance of MIS-structures fabricated on the basis of heteroepitaxial Hg1-xCdxTe (x = 0.22-0.23 and 0.31-0.32) films grown by molecular beam epitaxy was investigated in a wide temperature range. It is shown that a temperature drop from 77 K to 8 K results in a decrease of hysteresis of the capacitance-voltage (C-V) characteristics and a decrease of frequencies which corresponds to a high-frequency behaviour of C-V characteristics of MIS-structures based on n-HgCdTe (x = 0.22-0.23) with and without graded-gap layersand also for MIS-structures based on n-HgCdTe (x = 0.31-0.32). Temperature dependences of the resistance of the epitaxial film bulk and differential resistance of the space-charge region (SCR) in strong inversion mode were studied. The experimental results can be explained by the fact that for MIS-structures based on n-HgCdTe (x = 0.22-0.23) with the graded-gap layers and for MIS-structures based on n-HgCdTe (x = 0.31-0.32), the differential resistance of SCR is limited by Shockley-Read generation at 25-77 K. Differential resistance of SCR for MIS-structures based on n-HgCdTe (x = 0.22-0.23) without the graded-gap layers is limited by tunnelling through deep levels at 8-77 K.

  13. Experimental determination of three dimensional liquid rocket nozzle admittances.

    NASA Technical Reports Server (NTRS)

    Zinn, B. T.; Bell, W. A.; Daniel, B. R.; Smith, A. J., Jr.

    1972-01-01

    The three dimensional nozzle admittance, an important parameter in combustion instability studies, was experimentally measured for several nozzle configurations. The admittance values were obtained using a modification of the classical impedance tube technique. The modified impedance tube method measures the admittance of a duct termination in the presence of one dimensional mean flow and three dimensional oscillations. Values of the nozzle admittance were obtained from pressure amplitude measurements taken at discrete points along the length of the tube. To determine the effects of nozzle geometry, nozzles were tested with half-angles of 15, 30, and 45 degrees and entrance Mach numbers of 0.08, 0.16, and 0.20. The admittance results are presented as functions of nondimensional frequency for mixed first tangential-longitudinal modes. These results are compared with available theoretical predictions and favorable agreement between theory and experiment is shown.

  14. Automatically calibrating admittances in KATE's autonomous launch operations model

    NASA Astrophysics Data System (ADS)

    Morgan, Steve

    1992-09-01

    This report documents a 1000-line Symbolics LISP program that automatically calibrates all 15 fluid admittances in KATE's Autonomous Launch Operations (ALO) model. (KATE is Kennedy Space Center's Knowledge-based Autonomous Test Engineer, a diagnosis and repair expert system created for use on the Space Shuttle's various fluid flow systems.) As a new KATE application, the calibrator described here breaks new ground for KSC's Artificial Intelligence Lab by allowing KATE to both control and measure the hardware she supervises. By automating a formerly manual process, the calibrator: (1) saves the ALO model builder untold amounts of labor; (2) enables quick repairs after workmen accidently adjust ALO's hand valves; and (3) frees the modeler to pursue new KATE applications that previously were too complicated. Also reported are suggestions for enhancing the program: (1) to calibrate ALO's TV cameras, pumps, and sensor tolerances; and (2) to calibrate devices in other KATE models, such as the shuttle's LOX and Environment Control System (ECS).

  15. Automatically calibrating admittances in KATE's autonomous launch operations model

    NASA Technical Reports Server (NTRS)

    Morgan, Steve

    1992-01-01

    This report documents a 1000-line Symbolics LISP program that automatically calibrates all 15 fluid admittances in KATE's Autonomous Launch Operations (ALO) model. (KATE is Kennedy Space Center's Knowledge-based Autonomous Test Engineer, a diagnosis and repair expert system created for use on the Space Shuttle's various fluid flow systems.) As a new KATE application, the calibrator described here breaks new ground for KSC's Artificial Intelligence Lab by allowing KATE to both control and measure the hardware she supervises. By automating a formerly manual process, the calibrator: (1) saves the ALO model builder untold amounts of labor; (2) enables quick repairs after workmen accidently adjust ALO's hand valves; and (3) frees the modeler to pursue new KATE applications that previously were too complicated. Also reported are suggestions for enhancing the program: (1) to calibrate ALO's TV cameras, pumps, and sensor tolerances; and (2) to calibrate devices in other KATE models, such as the shuttle's LOX and Environment Control System (ECS).

  16. Admittance spectroscopy of copper indium diselenide/cadmium sulfide solar cells

    NASA Astrophysics Data System (ADS)

    Strifler, Walter A.

    This dissertation concentrates on admittance spectroscopy of CuInSe2/CdS heterojunction solar cells prepared by chemical spray pyrolysis (CSP) and by multiple-source evaporation (MSE). The primary goal is to examine some of the more important electrical characteristics of these heterojunctions and determine if the spray-pyrolyzed cells behave similar, albeit at a lower efficiency, to higher quality cells prepared by other techniques. The primary analytical tool used in this study is admittance spectroscopy. The theory of admittance spectroscopy is developed using the concept of equivalent circuits. The traditional temperature-swept technique for admittance spectroscopy is shown to be inadequate for measuring most heterojunction samples examined in this study because of the large parallel leakage conductance found in these devices. Instead, a frequency-swept admittance technique is developed and employed to correct for the parallel conductance effect and reveal the true nature of slow charge in the depletion layer. In addition to admittance spectroscopy, the two sets of solar cell diodes are characterized using a variety of measurement techniques including capacitance-voltage, current-voltage over spectral response, capacitance dispersion over wavelength, and solar efficiency. The different pieces of experimental data are discussed to form a self-consistent physical model of the polycrystalline solar cells. Charge transport across the diode junction is dominated by recombination processes within the CuInSe2 depletion layer for both sets of diodes although the large parallel conductance in the CSP diodes often masks this characteristic. The CSP solar cells exhibit a pronounced blue peak in the spectral response indicating that electron collection is the limiting factor in the overall short-circuit quantum efficiency. A large degree of capacitance dispersion is found in both sets of diodes. Supporting measurements indicate that the majority of this dispersion is due

  17. Simultaneous recovery of admittivity and body shape in electrical impedance tomography: an experimental evaluation

    NASA Astrophysics Data System (ADS)

    Dardé, Jérémi; Hyvönen, Nuutti; Seppänen, Aku; Staboulis, Stratos

    2013-08-01

    In this paper, the simultaneous retrieval of the exterior boundary shape and the interior admittivity distribution of an examined body in electrical impedance tomography is considered. The reconstruction method is built for the complete electrode model and it is based on the Fréchet derivative of the corresponding current-to-voltage map with respect to the body shape. The reconstruction problem is cast into the Bayesian framework, and maximum a posteriori estimates for the admittivity and the boundary geometry are computed. The feasibility of the approach is evaluated by experimental data from water tank measurements. The results demonstrate that the proposed method has potential for handling an unknown body shape in a practical setting.

  18. Coulometric differential FFT admittance voltammetry determination of Amlodipine in pharmaceutical formulation by nano-composite electrode.

    PubMed

    Norouzi, Parviz; Gupta, Vinod Kumar; Larijani, Bagher; Rasoolipour, Solmaz; Faridbod, Farnoush; Ganjali, Mohammad R

    2015-01-01

    An electrochemical detection technique based on combination of was coulometric differential fast Fourier transformation admittance voltammetry (CDFFTAV) and nano-composite film modified glassy carbon electrode was successfully applied for sensitive determination of Amlodipine. The nano-composite film was made by a mixture of ionic liquid, 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF4), multiwall carbon nanotube and Au nanoparticles as electrochemical mediators. Studies reveal that the irreversible oxidation of Amlodipine was highly facile on the electrode surface. The electrochemical response was established on calculation of the charge under the admittance peak, which was obtained by discrete integration of the admittance response in a selected potential range, obtained in a flow injection analysis. Once established the best operative optimum conditions, the resulting nano-composite film electrode showed a catalytic effect on the oxidation of the analyte. The response is linear in the Amlodipine concentration range of 1.0 × 10(-9) to 2.0 × 10(-7)M with a detection limit of 1.25 × 10(-10)M. Moreover, the proposed technique exhibited high sensitivity, fast response time (less than 6s) and long-term stability and reproducibility around 96%, and it was successfully used to the determination of Amlodipine content in the pharmaceutical formulation. PMID:25281143

  19. Admittance of multiterminal quantum Hall conductors at kilohertz frequencies

    SciTech Connect

    Hernández, C.; Consejo, C.; Chaubet, C.; Degiovanni, P.

    2014-03-28

    We present an experimental study of the low frequency admittance of quantum Hall conductors in the [100 Hz, 1 MHz] frequency range. We show that the frequency dependence of the admittance of the sample strongly depends on the topology of the contacts connections. Our experimental results are well explained within the Christen and Büttiker approach for finite frequency transport in quantum Hall edge channels taking into account the influence of the coaxial cables capacitance. In the Hall bar geometry, we demonstrate that there exists a configuration in which the cable capacitance does not influence the admittance measurement of the sample. In this case, we measure the electrochemical capacitance of the sample and observe its dependence on the filling factor.

  20. Chinchilla middle-ear admittance and sound power: High-frequency estimates and effects of inner-ear modifications

    PubMed Central

    Ravicz, Michael E.; Rosowski, John J.

    2012-01-01

    The middle-ear input admittance relates sound power into the middle ear (ME) and sound pressure at the tympanic membrane (TM). ME input admittance was measured in the chinchilla ear canal as part of a larger study of sound power transmission through the ME into the inner ear. The middle ear was open, and the inner ear was intact or modified with small sensors inserted into the vestibule near the cochlear base. A simple model of the chinchilla ear canal, based on ear canal sound pressure measurements at two points along the canal and an assumption of plane-wave propagation, enables reliable estimates of YTM, the ME input admittance at the TM, from the admittance measured relatively far from the TM. YTM appears valid at frequencies as high as 17 kHz, a much higher frequency than previously reported. The real part of YTM decreases with frequency above 2 kHz. Effects of the inner-ear sensors (necessary for inner ear power computation) were small and generally limited to frequencies below 3 kHz. Computed power reflectance was ∼0.1 below 3.5 kHz, lower than with an intact ME below 2.5 kHz, and nearly 1 above 16 kHz. PMID:23039439

  1. 9 CFR 117.3 - Admittance of animals.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 9 Animals and Animal Products 1 2013-01-01 2013-01-01 false Admittance of animals. 117.3 Section 117.3 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE VIRUSES, SERUMS, TOXINS, AND ANALOGOUS PRODUCTS; ORGANISMS AND VECTORS ANIMALS AT...

  2. 9 CFR 117.3 - Admittance of animals.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 9 Animals and Animal Products 1 2014-01-01 2014-01-01 false Admittance of animals. 117.3 Section 117.3 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE VIRUSES, SERUMS, TOXINS, AND ANALOGOUS PRODUCTS; ORGANISMS AND VECTORS ANIMALS AT...

  3. 9 CFR 117.3 - Admittance of animals.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 9 Animals and Animal Products 1 2011-01-01 2011-01-01 false Admittance of animals. 117.3 Section 117.3 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE VIRUSES, SERUMS, TOXINS, AND ANALOGOUS PRODUCTS; ORGANISMS AND VECTORS ANIMALS AT...

  4. 9 CFR 117.3 - Admittance of animals.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 9 Animals and Animal Products 1 2010-01-01 2010-01-01 false Admittance of animals. 117.3 Section 117.3 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE VIRUSES, SERUMS, TOXINS, AND ANALOGOUS PRODUCTS; ORGANISMS AND VECTORS ANIMALS AT...

  5. 9 CFR 117.3 - Admittance of animals.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 9 Animals and Animal Products 1 2012-01-01 2012-01-01 false Admittance of animals. 117.3 Section 117.3 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE VIRUSES, SERUMS, TOXINS, AND ANALOGOUS PRODUCTS; ORGANISMS AND VECTORS ANIMALS AT...

  6. Impact and admittance modeling of the Isidis Planitia, Mars

    NASA Astrophysics Data System (ADS)

    Mancinelli, Paolo; Mondini, Alessandro C.; Pauselli, Cristina; Federico, Costanzo

    2015-11-01

    In this study, the impact event that produced the Martian Isidis basin (0-20°N and 70-100°E) was modeled using the iSALE hydrocode, and the current lithospheric structure was obtained comparing the calculated admittance from topography and gravity data, with the admittance from top-load and bottom-load flexure models. The best-fit admittance model was obtained using a bottom-load flexure with a thinned crust of 10 km, likely formed by cooling of the surficial melt pool after the impact, and an elastic thickness of 36 km. We found that the impact produced crustal excavation and thickening, surficial melt pool and temperatures >1500 K beneath the area where the free-air maxima is observed. The geometry resulting from the impact modeling is compatible with the radius of the Isidis basin. Derived thermal gradient and heat flux are in agreement with an early-Noachian epoch for the Isidis impact event and with the intense volcanic activity that followed the impact.

  7. Cross-spectral recognition method of bridge deck aerodynamic admittance function

    NASA Astrophysics Data System (ADS)

    Zhao, Lin; Ge, Yaojun

    2015-12-01

    This study proposes a new identification algorithm about the admittance function, which can estimate the full set of six aerodynamic admittance functions considering cross power spectral density functions about the forces and the turbulence components. The method was first numerically validated through Monte Carlo simulations, and then adopted to estimate the aerodynamic admittance of a streamlined bridge deck. The identification method was further validated through a comparison between the numerical calculation and wind tunnel tests on a moving bridge section.

  8. The long-wavelength admittance and effective elastic thickness of the Canadian Shield

    NASA Astrophysics Data System (ADS)

    Kirby, J. F.; Swain, C. J.

    2014-06-01

    The strength of the cratonic lithosphere has been controversial. On the one hand, many estimates of effective elastic thickness (Te) greatly exceed the crustal thickness, but on the other the great majority of cratonic earthquakes occur in the upper crust. This implies that the seismogenic thickness of cratons is much smaller than Te, whereas in the ocean basins they are approximately the same, leading to suspicions about the large Te estimates. One region where such estimates have been questioned is the Canadian Shield, where glacial isostatic adjustment (GIA) and mantle convection are thought to contribute to the long-wavelength undulations of the topography and gravity. To date these have not been included in models used to estimate Te from topography and gravity which conventionally are based only on loading and flexure. Here we devise a theoretical expression for the free-air (gravity/topography) admittance that includes the effects of GIA and convection as well as flexure and use it to estimate Te over the Canadian Shield. We use wavelet transforms for estimating the observed admittances, after showing that multitaper estimates, which have hitherto been popular for Te studies, have poor resolution at the long wavelengths where GIA and convection predominate, compared to wavelets. Our results suggest that Te over most of the shield exceeds 80 km, with a higher-Te core near the southwest shore of Hudson Bay. This means that the lack of mantle earthquakes in this craton is simply due to its high strength compared to the applied stresses.

  9. Increasing Immunization Compliance by Reducing Provisional Admittance

    ERIC Educational Resources Information Center

    Davis, Wendy S.; Varni, Susan E.; Barry, Sara E.; Frankowski, Barbara L.; Harder, Valerie S.

    2016-01-01

    Students in Vermont with incomplete or undocumented immunization status are provisionally admitted to schools and historically had a calendar year to resolve their immunization status. The process of resolving these students' immunization status was challenging for school nurses. We conducted a school-based quality improvement effort to increase…

  10. Bio-telemetric device for measurement of left ventricular pressure-volume loops using the admittance technique in conscious, ambulatory rats

    PubMed Central

    Raghavan, Karthik; Feldman, Marc D; Porterfield, John E; Larson, Erik R; Jenkins, J Travis; Escobedo, Daniel; Pearce, John A

    2011-01-01

    This paper presents the design, construction and testing of a device to measure pressure volume loops in the left ventricle of conscious, ambulatory rats. Pressure is measured with a standard sensor, but volume is derived from data collected from a tetrapolar electrode catheter using a novel admittance technique. There are two main advantages of the admittance technique to measure volume. First, the contribution from the adjacent muscle can be instantaneously removed. Second, the admittance technique incorporates the nonlinear relationship between the electric field generated by the catheter and the blood volume. A low power instrument weighing 27 g was designed, which takes pressure-volume loops every 2 minutes and runs for 24 hours. Pressure-volume data are transmitted wirelessly to a base station. The device was first validated in thirteen rats with an acute preparation with 2-D echocardiography used to measure true volume. From an accuracy standpoint, the admittance technique is superior to both the conductance technique calibrated with hypertonic saline injections, and calibrated with cuvettes. The device was then tested in six rats with a 24-hour chronic preparation. Stability of the animal preparation and careful calibration are important factors affecting the success of the device. PMID:21606560

  11. Thermal-mechanical-noise-based CMUT characterization and sensing.

    PubMed

    Gurun, Gokce; Hochman, Michael; Hasler, Paul; Degertekin, F Levent

    2012-06-01

    When capacitive micromachined ultrasonic transducers (CMUTs) are monolithically integrated with custom-designed low-noise electronics, the output noise of the system can be dominated by the CMUT thermal-mechanical noise both in air and in immersion even for devices with low capacitance. Because the thermal-mechanical noise can be related to the electrical admittance of the CMUTs, this provides an effective means of device characterization. This approach yields a novel method to test the functionality and uniformity of CMUT arrays and the integrated electronics when a direct connection to CMUT array element terminals is not available. Because these measurements can be performed in air at the wafer level, the approach is suitable for batch manufacturing and testing. We demonstrate this method on the elements of an 800-μm-diameter CMUT-on-CMOS array designed for intravascular imaging in the 10 to 20 MHz range. Noise measurements in air show the expected resonance behavior and spring softening effects. Noise measurements in immersion for the same array provide useful information on both the acoustic cross talk and radiation properties of the CMUT array elements. The good agreement between a CMUT model based on finite difference and boundary element methods and the noise measurements validates the model and indicates that the output noise is indeed dominated by thermal-mechanical noise. The measurement method can be exploited to implement CMUT-based passive sensors to measure immersion medium properties, or other parameters affecting the electro-mechanics of the CMUT structure. PMID:22718877

  12. Quality control of dairy products using single frequency admittance measurements

    NASA Astrophysics Data System (ADS)

    Mabrook, M. F.; Darbyshire, A. M.; Petty, M. C.

    2006-02-01

    A reusable device for the detection of adulteration in dairy products such as milk and cream has been developed. The ac electrical admittance spectra of different samples have been studied using both uncoated and alkyl mercaptan-coated gold electrodes. Uncoated gold electrodes exhibited a polarization at around 250 Hz for full fat milk, while mercaptan-coated gold electrodes showed a similar effect at around 2 kHz. The characteristics at 100 kHz and 8 °C for all skimmed milk samples revealed a linear decrease in conductance with increasing water content over the entire range of water concentration. In contrast, the conductance of full fat milk, single and double cream, showed a linear decrease only at added water concentration higher than 6%. At lower concentrations, these dairy products exhibited anomalous conductivity maxima.

  13. Use of paravascular admittance waveforms to monitor relative change in arterial blood pressure

    NASA Astrophysics Data System (ADS)

    Zielinski, Todd M.; Hettrick, Doug; Cho, Yong

    2010-04-01

    Non-invasive methods to monitor ambulatory blood pressure often have limitations that can affect measurement accuracy and patient adherence [1]. Minimally invasive measurement of a relative blood pressure surrogate with an implantable device may provide a useful chronic diagnostic and monitoring tool. We assessed a technique that uses electrocardiogram and paravascular admittance waveform morphology analysis to one, measure a time duration (vascular tone index, VTI in milliseconds) change from the electrocardiogram R-wave to admittance waveform peak and two, measure the admittance waveform minimum, maximum and magnitude as indicators of change in arterial compliance/distensibility or pulse pressure secondary to change in afterload. Methods: Five anesthetized domestic pigs (32 ± 4.2 kg) were used to study the effects of phenylephrine (1-5 ug/kg/min) on femoral artery pressure and admittance waveform morphology measured with a quadrapolar electrode array catheter placed next to the femoral artery to assess the relative change in arterial compliance due to change in peripheral vascular tone. Results: Statistical difference was observed (p < 0.05) comparing baseline VTI to phenylephrine VTI (246 ± .05 ms to 320 ± .07 ms) and baseline admittance waveform maximum to phenylephrine admittance waveform maximum (0.0148 ± .002 siemens to 0.0151 ± .002 siemens). Conclusion: Chronic minimally invasive admittance measurement techniques that monitor relative change in blood pressure may be suitable for implantable devices to detect progression of cardiovascular disease such as hypertension.

  14. Surface acoustic admittance of highly porous open-cell, elastic foams

    NASA Technical Reports Server (NTRS)

    Lambert, R. F.

    1983-01-01

    This work presents a comprehensive study of the surface acoustic admittance properties of graded sizes of open-cell foams that are highly porous and elastic. The intrinsic admittance as well as properties of samples of finite depth were predicted and then measured for sound at normal incidence over a frequency range extending from about 35-3500 Hz. The agreement between theory and experiment for a range of mean pore size and volume porosity is excellent. The implications of fibrous structure on the admittance of open-cell foams is quite evident from the results.

  15. 48 CFR 3022.101-70 - Admittance of union representatives to DHS installations.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... APPLICATION OF LABOR LAWS TO GOVERNMENT ACQUISITIONS Basic Labor Policies 3022.101-70 Admittance of union... Administration or United States Secret Service installations and work sites is not governed by this rule, but...

  16. 48 CFR 3022.101-70 - Admittance of union representatives to DHS installations.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... APPLICATION OF LABOR LAWS TO GOVERNMENT ACQUISITIONS Basic Labor Policies 3022.101-70 Admittance of union... Administration or United States Secret Service installations and work sites is not governed by this rule, but...

  17. 48 CFR 3022.101-70 - Admittance of union representatives to DHS installations.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... APPLICATION OF LABOR LAWS TO GOVERNMENT ACQUISITIONS Basic Labor Policies 3022.101-70 Admittance of union... Administration or United States Secret Service installations and work sites is not governed by this rule, but...

  18. 48 CFR 3022.101-70 - Admittance of union representatives to DHS installations.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... APPLICATION OF LABOR LAWS TO GOVERNMENT ACQUISITIONS Basic Labor Policies 3022.101-70 Admittance of union... Administration or United States Secret Service installations and work sites is not governed by this rule, but...

  19. Temperature admittance spectroscopy of boron doped chemical vapor deposition diamond

    NASA Astrophysics Data System (ADS)

    Zubkov, V. I.; Kucherova, O. V.; Bogdanov, S. A.; Zubkova, A. V.; Butler, J. E.; Ilyin, V. A.; Afanas'ev, A. V.; Vikharev, A. L.

    2015-10-01

    Precision admittance spectroscopy measurements over wide temperature and frequency ranges were carried out for chemical vapor deposition epitaxial diamond samples doped with various concentrations of boron. It was found that the experimentally detected boron activation energy in the samples decreased from 314 meV down to 101 meV with an increase of B/C ratio from 600 to 18000 ppm in the gas reactants. For the heavily doped samples, a transition from thermally activated valence band conduction to hopping within the impurity band (with apparent activation energy 20 meV) was detected at temperatures 120-150 K. Numerical simulation was used to estimate the impurity DOS broadening. Accurate determination of continuously altering activation energy, which takes place during the transformation of conduction mechanisms, was proposed by numerical differentiation of the Arrhenius plot. With increase of boron doping level the gradual decreasing of capture cross section from 3 × 10-13 down to 2 × 10-17 cm2 was noticed. Moreover, for the hopping conduction the capture cross section becomes 4 orders of magnitude less (˜2 × 10-20 cm2). At T > Troom in doped samples the birth of the second conductance peak was observed. We attribute it to a defect, related to the boron doping of the material.

  20. Temperature admittance spectroscopy of boron doped chemical vapor deposition diamond

    SciTech Connect

    Zubkov, V. I. Kucherova, O. V.; Zubkova, A. V.; Ilyin, V. A.; Afanas'ev, A. V.; Bogdanov, S. A.; Vikharev, A. L.; Butler, J. E.

    2015-10-14

    Precision admittance spectroscopy measurements over wide temperature and frequency ranges were carried out for chemical vapor deposition epitaxial diamond samples doped with various concentrations of boron. It was found that the experimentally detected boron activation energy in the samples decreased from 314 meV down to 101 meV with an increase of B/C ratio from 600 to 18000 ppm in the gas reactants. For the heavily doped samples, a transition from thermally activated valence band conduction to hopping within the impurity band (with apparent activation energy 20 meV) was detected at temperatures 120–150 K. Numerical simulation was used to estimate the impurity DOS broadening. Accurate determination of continuously altering activation energy, which takes place during the transformation of conduction mechanisms, was proposed by numerical differentiation of the Arrhenius plot. With increase of boron doping level the gradual decreasing of capture cross section from 3 × 10{sup −13} down to 2 × 10{sup −17} cm{sup 2} was noticed. Moreover, for the hopping conduction the capture cross section becomes 4 orders of magnitude less (∼2 × 10{sup −20} cm{sup 2}). At T > T{sub room} in doped samples the birth of the second conductance peak was observed. We attribute it to a defect, related to the boron doping of the material.

  1. Global Admittance Estimates of Elastic and Crustal Thickness of Venus: Results from Top, Hot Spot, and Bottom Loading Models

    NASA Technical Reports Server (NTRS)

    Smrekar, S. E.; Anderson, F. S.

    2005-01-01

    We have calculated admittance spectra using the spatio-spectral method [14] for Venus by moving the central location of the spectrum over a 1 grid, create 360x180 admittance spectra. We invert the observed admittance using top-loading (TL), hot spot (HS), and bottom loading (BL) models, resulting in elastic, crustal, and lithospheric thickness estimates (Te, Zc, and Zl) [0]. The result is a global map for interpreting subsurface structure. Estimated values of Te and Zc concur with previous TL local admittance results, but BL estimates indicate larger values than previously suspected.

  2. Inconsistent Definitions of the Pressure-Coupled Response and the Admittance of Solid Propellants

    NASA Technical Reports Server (NTRS)

    Cardiff, Eric H.

    2003-01-01

    When an acoustic wave is present in a solid propellant combustion environment, the mass flux from the combustion zone oscillates at the same frequency as the acoustics. The acoustic wave is either amplified or attenuated by the response of the combustion to the acoustic disturbance. When the acoustic wave is amplified, this process is called combustion instability. The amplification is quantitatively measured by a response function. The ability to predict combustion stability for a solid propellant formulation is essential to the formulator to prevent or minimize the effects of instabilities, such as an oscillatory thrust. Unfortunately, the prediction of response values for a particular propellant remains a technical challenge. Most predictions of the response of propellants are based on test data, but there are a number of questions about the reliability of the standard test method, the T-burner. Alternate methods have been developed to measure the response of a propellant, including the ultrasound burner, the magnetic flowmeter and the rotating valve burner, but there are still inconsistencies between the results obtained by these different methods. Aside from the experimental differences, the values of the pressure-coupled responses obtained by different researchers are often compared erroneously, for the simple reason that inconsistencies in the definitions of the responses and admittances are not considered. The use of different definitions has led to substantial confusion since the first theoretical treatments of the problem by Hart and McClure in 1959. The definitions and relations derived here seek to alleviate this problem.

  3. Effect of nonzero surface admittance on receptivity and stability of compressible boundary layer

    NASA Technical Reports Server (NTRS)

    Choudhari, Meelan

    1994-01-01

    The effect of small-amplitude short-scale variations in surface admittance on the acoustic receptivity and stability of two-dimensional compressible boundary layers is examined. In the linearized limit, the two problems are shown to be related both physically and mathematically. This connection between the two problems is used, in conjunction with some previously reported receptivity results, to infer the modification of stability properties due to surface permeability. Numerical calculations are carried out for a self-similar flat-plate boundary layer at subsonic and low supersonic speeds. Variations in mean suction velocity at the perforated admittance surface can also induce receptivity to an acoustic wave. For a subsonic boundary layer, the dependence of admittance-induced receptivity on the acoustic-wave orientation is significantly different from that of the receptivity produced via mean suction variation. The admittance-induced receptivity is generally independent of the angle of acoustic incidence, except in a relatively narrow range of upstream-traveling waves for which the receptivity becomes weaker. However, this range of angles is precisely that for which the suction-induced receptivity tends to be large. At supersonic Mach numbers, the admittance-induced receptivity to slow acoustic models is relatively weaker than that in the case of the fast acoustic modes. We also find that purely real values for the surface admittance tend to have a destabilizing effect on the evolution of an instability wave over a slightly permeable surface. The limits on the validity of the linearized approximation are also assessed in one specific case.

  4. Admittance of Au/1,4-benzenedithiol/Au single-molecule junctions

    NASA Astrophysics Data System (ADS)

    Yamauchi, Kazumasa; Kurokawa, Shu; Sakai, Akira

    2012-12-01

    Employing the admittance formula for double-barrier junctions [Fu and Dudley, Phys. Rev. Lett. 70, 65 (1993)], we have estimated an ac susceptance (imaginary part of admittance) of Au/1,4-benzenedithiol/Au single-molecule junctions from their current-voltage characteristics. In the MHz regime, we find that the junction susceptance shows a very small (˜0.1 aF) capacitive component that can be entirely masked by a larger electrode capacitance. Direct ac signal transmission measurements up to 1 GHz reveal no molecular signals and confirm the smallness of the molecular capacitance in the MHz regime.

  5. Non-invasive monitoring of hemodynamic changes during hemodialysis by the use of a newly developed admittance cardiograph.

    PubMed

    Yoshii, Masayoshi; Minami, Junichi; Ishimitsu, Toshihiko; Yamakoshi, Ken-ichi; Matsuoka, Hiroaki

    2005-04-01

    Only a little information is available for the evaluation of the complex hemodynamic changes that occur during hemodialysis. Recently, we developed the transthoracic electrical admittance cardiograph for repeated measurements of cardiac output, and monitored hemodynamic changes during hemodialysis by the use of this device. We measured cardiovascular hemodynamic and autonomic parameters non-invasively during 210 min of hemodialysis in 19 chronic hemodialysis patients who for more than 2 months had no history of cardiovascular collapses during hemodialysis. Blood pressure was monitored every 10 min using a cuff-oscillometric device (TM-2425; A & D, Tokyo, Japan). Cardiac output was monitored on a beat-by-beat basis by a newly developed electrical admittance cardiograph (NICOVIEW PA1100; NEC, Tokyo, Japan). Electrocardiogram R-R intervals were also monitored by the TM-2425. Power spectral analysis of R-R intervals was performed to obtain the low-frequency (LF; 0.05-0.15 Hz) and the high-frequency (HF; 0.15-0.40 Hz) components based on an autoregressive model. Change in circulatory blood volume was also monitored by a CRIT-LINE (In-Line Diagnostics, Riverdale, UT, USA). Although blood volume declined significantly by 16.3 +/- 1.4% (mean +/- SE) during hemodialysis (P < 0.0001), mean blood pressure did not change significantly. Heart rate increased significantly from the initial values of 76.3 +/- 3.4-86.4 +/- 4.9 beats/min (P = 0.03). Cardiac output and stroke volume decreased significantly from 4.47 +/- 0.30 to 2.91 +/- 0.32 L/min (P < 0.0001), and from 57.0 +/- 3.7 to 33.9 +/- 3.1 mL (P < 0.0001), respectively. Total peripheral vascular resistance increased significantly from 1940 +/- 146 to 3117 +/- 280 dyne x s x cm(5) (P < 0.0001). The LF component did not show significant change, while the HF component decreased significantly (P = 0.007), and the LF/HF ratio increased significantly (P = 0.03). These results suggest that a reduction in parasympathetic nerve

  6. Admittance model for the shuttle remote manipulator system in four configurations. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Papadopoulos, Loukas; Tolson, Robert H.

    1993-01-01

    A possible scenario for robot task performance in space is to mount two small, dexterous arms to the end of the Shuttle Remote Manipulator System (SRMS). As these small robots perform tasks, the flexibility of the SRMS may cause unsuccessful task executions. In order to simulate the dynamic coupling between the SRMS and the arms, admittance models of the SRMS in four brakes locked configurations were developed. The admittance model permits calculation of the SRMS end-effector response due to end-effector disturbing forces. The model will then be used in conjunction with a Stewart Platform, a vehicle emulation system. An application of the admittance model was shown by simulating the disturbing forces using two SRMS payloads, the Dextrous Orbital Servicing System (DOSS) manipulator and DOSS carrying a 1000 lb. cylinder. Mode by mode comparisons were conducted to determine the minimum number of modes required in the admittance model while retaining dynamic fidelity. It was determined that for all four SRMS configurations studied, between 4 and 6 modes of the SRMS structure (depending on the excitation loads) were sufficient to retain tolerance of 0.01 inches and 0.01 deg. These tolerances correspond to the DOSS manipulator carrying no object. When the DOSS carries the 1000 lb. cylinder, between 15 and 20 modes were sufficient, approximately three or four times as many modes as for the unloaded case.

  7. A study of the ionic conduction of mica surface by admittance spectroscopy

    NASA Astrophysics Data System (ADS)

    Dolci, D.; Aloisi, G.; Lanzi, L.; Carlà, M.

    2007-08-01

    The ionic conduction on the surface of humid mica has been analyzed by admittance spectroscopy as a function of relative humidity for different surface treatments. Measurements at low frequency indicate that water adsorption proceeds first in the form of a strongly adsorbed uniform thin layer, then with the formation of highly inhomogeneous thick aggregates.

  8. Damage detection on the joint of steel frame through high-frequency admittance signals

    NASA Astrophysics Data System (ADS)

    Wang, Dansheng; Zhu, Hongping; Zhou, Huaqiang; Yang, Haiping

    2008-11-01

    The basic idea of a piezoelectric admittance (reciprocal of impedance) technique for structural health monitoring is presented in this paper. An experimental study on damage detection of a steel frame structure is operated by the use of the high-frequency piezoelectric admittance signals. In this experiment, three PZT active sensors are bonded to three different components around a joint of the steel frame separately, and the looseness of bolts is identified by monitoring the variations of piezoelectric admittance measurements. From the experimental results it is found that the PZT active sensors hold the ability to detect structural local damage, i.e. they are insensitive to the damage in far fields. Subsequently, two damage indexes, the covariance and the cross correlation coefficient between two real admittance data sets are defined respectively, by which the extent of damage of the frame structure is evaluated. It is found that the cross correlation coefficient index can correctly reflect the damage extent of the frame structure qualitatively in different frequency ranges, but the covariance index can not.

  9. 48 CFR 1222.101-70 - Admittance of union representatives to DOT installations.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Basic Labor Policies 1222.101-70 Admittance of union representatives to DOT installations. (a) It is DOT policy to admit labor union representatives of contractor employees to DOT installations to visit work sites and transact labor union business with contractors, their employees, or union stewards pursuant...

  10. 48 CFR 1222.101-70 - Admittance of union representatives to DOT installations.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Basic Labor Policies 1222.101-70 Admittance of union representatives to DOT installations. (a) It is DOT policy to admit labor union representatives of contractor employees to DOT installations to visit work sites and transact labor union business with contractors, their employees, or union stewards pursuant...

  11. 48 CFR 1222.101-70 - Admittance of union representatives to DOT installations.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Basic Labor Policies 1222.101-70 Admittance of union representatives to DOT installations. (a) It is DOT policy to admit labor union representatives of contractor employees to DOT installations to visit work sites and transact labor union business with contractors, their employees, or union stewards pursuant...

  12. 48 CFR 1222.101-70 - Admittance of union representatives to DOT installations.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 48 Federal Acquisition Regulations System 5 2014-10-01 2014-10-01 false Admittance of union representatives to DOT installations. 1222.101-70 Section 1222.101-70 Federal Acquisition Regulations System DEPARTMENT OF TRANSPORTATION SOCIOECONOMIC PROGRAMS APPLICATION OF LABOR LAWS TO GOVERNMENT ACQUISITIONS Basic Labor Policies...

  13. An analysis of light-induced admittance changes in rod outer segments

    PubMed Central

    Falk, G.; Fatt, P.

    1973-01-01

    1. Measurements were made of the time course and amplitude of the change in real part of admittance, ΔG, of a suspension of frog rod outer segments, following a flash of light bleaching about 1% of the rhodopsin content of the rods. The measurements, based on the use of a specially designed marginal oscillator, covered the frequency range between 500 Hz and 17 MHz. 2. The components of response, previously described for rods prepared by a method involving exposure to strongly hypertonic sucrose solutions, are present in similar form when rods are isolated and maintained in isotonic solutions made up with equi-osmotic concentrations of NaCl and sucrose or with Na2SO4. 3. Component I, identified as a slowly developing positive ΔG apparent at very low frequencies, is frequency-independent up to the characteristic frequency of admittance for the suspension, fY (about 2 MHz for rods suspended in a solution having the conductivity of Ringer solution), but decreases at still higher frequencies. 4. Component II, identified as a rapidly developing positive ΔG which appears only above a critical frequency about 2·5 decades below fY, increases approximately logarithmically with frequency to reach a limiting amplitude in the region of fY. 5. The amplitude of component II, ΔGII, measured in the region of fY, varies linearly with the conductivity of the suspending medium, Go, under conditions in which the conductivity of the rod interior is also a linear function of the external conductivity. The relation for a flash bleaching 1% of the rhodopsin content of the dark-adapted rod is [Formula: see text] 6. Measurements made on rods suspended in a low-conductivity solution, which has the effect of reducing the conductivity of the rod interior to about one ninth its value for rods suspended in Ringer solution, reveal a decline in component II for frequencies above 8 MHz. 7. To explain the frequency dependence of component II and its dependence on conductivity, it is proposed

  14. Dielectric studies of boron sub phthalocyanine chloride thin films by admittance spectroscopic techniques

    NASA Astrophysics Data System (ADS)

    Kalia, Sameer; Mahajan, Aman; Neerja, Sharma, Anshul Kumar; Kumar, Sanjeev; Bedi, R. K.

    2016-05-01

    The dielectric properties of Boron Sub Phthalocyanine Chloride (Cl-SubPc) thermally deposited on ITO substrate have been studied using admittance spectroscopic techniques. The I-V and capacitance -frequency (C-F) studies at various bias voltages reveal that the mobility of charge carriers decrease with bias voltage, however the conduction phenomenon still remain hopping in nature. From the differential susceptance curve, the contribution of the Schottky barrier contact in the charge carrier concentration was found to be absent. The mobility of charge carriers have been determined using differential susceptance variation and from the phase of admittance curve. The values obtained in two cases have been found to be in agreement with each other.

  15. Admittance-voltage profiling of AlxGa1-xN/GaN heterostructures: Frequency dependence of capacitance and conductance

    NASA Astrophysics Data System (ADS)

    Köhler, K.; Pletschen, W.; Godejohann, B.; Müller, S.; Menner, H. P.; Ambacher, O.

    2015-11-01

    Admittance-voltage profiling of AlxGa1-xN/GaN heterostructures was used to determine the frequency dependent capacitance and conductance of FET devices in the frequency range from 50 Hz to 1 MHz. The nominally undoped low pressure metal-organic vapor-phase epitaxy structures were grown with an Al-content of 30%. An additional 1 nm thick AlN interlayer was placed in one structure before the Al0.3Ga0.7N layer growth. For frequencies below 108 Hz it is convenient to use equivalent circuits to represent electric or dielectric properties of a material, a method widely used, for example, in impedance spectroscopy. We want to emphasize the relation between frequency dependent admittance-voltage profiling and the corresponding equivalent circuits to the complex dielectric function. Debye and Drude models are used for the description of the frequency dependent admittance profiles in a range of depletion onset of the two-dimensional electron gas. Capacitance- and conductance-frequency profiles are fitted in the entire measured range by combining both models. Based on our results, we see contributions to the two-dimensional electron gas for our samples from surface states (80%) as well as from background doping in the Al0.3Ga0.7N barriers (20%). The specific resistance of the layers below the gate is above 105 Ω cm for both samples and increases with increasing negative bias, i.e., the layers below the gate are essentially depleted. We propose that the resistance due to free charge carriers, determined by the Drude model, is located between gate and drain and, because of the AlN interlayer, the resistance is lowered by a factor of about 30 if compared to the sample without an AlN layer.

  16. Transient excitation and mechanical admittance test techniques for prediction of payload vibration environments

    NASA Technical Reports Server (NTRS)

    Kana, D. D.; Vargas, L. M.

    1977-01-01

    Transient excitation forces were applied separately to simple beam-and-mass launch vehicle and payload models to develop complex admittance functions for the interface and other appropriate points on the structures. These measured admittances were then analytically combined by a matrix representation to obtain a description of the coupled system dynamic characteristics. Response of the payload model to excitation of the launch vehicle model was predicted and compared with results measured on the combined models. These results are also compared with results of earlier work in which a similar procedure was employed except that steady-state sinusoidal excitation techniques were included. It is found that the method employing transient tests produces results that are better overall than the steady state methods. Furthermore, the transient method requires far less time to implement, and provides far better resolution in the data. However, the data acquisition and handling problem is more complex for this method. It is concluded that the transient test and admittance matrix prediction method can be a valuable tool for development of payload vibration tests.

  17. Characterisation of defects in p-GaN by admittance spectroscopy

    NASA Astrophysics Data System (ADS)

    Elsherif, O. S.; Vernon-Parry, K. D.; Evans-Freeman, J. H.; Airey, R. J.; Kappers, M.; Humphreys, C. J.

    2012-08-01

    Mg-doped GaN films have been grown on (0 0 0 1) sapphire using metal organic vapour phase epitaxy. Use of different buffer layer strategies caused the threading dislocation density (TDD) in the GaN to be either approximately 2×109 cm-2 or 1×1010 cm-2. Frequency-dependent capacitance and conductance measurements at temperatures up to 450 K have been used to study the electronic states associated with the Mg doping, and to determine how these are affected by the TDD. Admittance spectroscopy of the films finds a single impurity-related acceptor level with an activation energy of 160±10 meV for [Mg] of about 1×1019 cm-3, and 120±10 eV as the Mg precursor flux decreased. This level is thought to be associated with the Mg acceptor state. The TDD has no discernible effect on the trap detected by admittance spectroscopy. We compare these results with cathodoluminescence measurements reported in the literature, which reveal that most threading dislocations are non-radiative recombination centres, and discuss possible reasons why our admittance spectroscopy have not detected electrically active defects associated with threading dislocations.

  18. Left ventricular epicardial admittance measurement for detection of acute LV dilation

    PubMed Central

    Porterfield, John E.; Larson, Erik R.; Jenkins, James T.; Escobedo, Daniel; Valvano, Jonathan W.; Pearce, John A.

    2011-01-01

    There are two implanted heart failure warning systems incorporated into biventricular pacemakers/automatic implantable cardiac defibrillators and tested in clinical trials: right heart pressures, and lung conductance measurements. However, both warning systems postdate measures of the earliest indicator of impending heart failure: left ventricular (LV) volume. There are currently no proposed implanted technologies that can perform LV blood volume measurements in humans. We propose to solve this problem by incorporating an admittance measurement system onto currently deployed biventricular and automatic implantable cardiac defibrillator leads. This study will demonstrate that an admittance measurement system can detect LV blood conductance from the epicardial position, despite the current generating and sensing electrodes being in constant motion with the heart, and with dynamic removal of the myocardial component of the returning voltage signal. Specifically, in 11 pigs, it will be demonstrated that 1) a physiological LV blood conductance signal can be derived; 2) LV dilation in response to dose-response intravenous neosynephrine can be detected by blood conductance in a similar fashion to the standard of endocardial crystals when admittance is used, but not when only traditional conductance is used; 3) the physiological impact of acute left anterior descending coronary artery occlusion and resultant LV dilation can be detected by blood conductance, before the anticipated secondary rise in right ventricular systolic pressure; and 4) a pleural effusion simulated by placing saline outside the pericardium does not serve as a source of artifact for blood conductance measurements. PMID:21148342

  19. Observation of lower defect density in CH3NH3Pb(I,Cl)3 solar cells by admittance spectroscopy

    NASA Astrophysics Data System (ADS)

    Jiang, Minlin; Lan, Fei; Zhao, Bingxin; Tao, Quan; Wu, Jiamin; Gao, Di; Li, Guangyong

    2016-06-01

    The introduction of Cl into CH3NH3PbI3 precursors is reported to enhance the performance of CH3NH3PbI3 solar cell, which is attributed to the significantly increased diffusion lengths of carriers in CH3NH3Pb(I,Cl)3 solar cell. It has been assumed but never experimentally approved that the defect density in CH3NH3Pb(I,Cl)3 solar cell should be reduced according to the higher carrier lifetime observed from photoluminescence (PL) measurement. We have fabricated CH3NH3Pb(I,Cl)3 solar cell by adding a small amount of Cl source into CH3NH3PbI3 precursor. The performance of CH3NH3Pb(I,Cl)3 solar cell is significantly improved from 15.39% to 18.60%. Results from scanning electron microscopy and X-ray diffraction indicate that the morphologies and crystal structures of CH3NH3PbI3 and CH3NH3Pb(I,Cl)3 thin films remain unchanged. Open circuit voltage decay and admittance spectroscopy characterization jointly approve that Cl plays an extremely important role in suppressing the formation of defects in perovskite solar cells.

  20. Dependence of electric current through human body on parameters of 3-0 network in range of high insulation admittance

    NASA Astrophysics Data System (ADS)

    Motuzko, F. Y.; Trubitsyn, A. V.

    1985-04-01

    The electric current I sub h through a human body touching one phase of a 3-0 network is calculated on the basis of the conventional equivalent circuit for the general case of unequal insulation admittances in all three phases. The two extreme cases here are all three insulation admittances approaching zero or infinity respectively. The theoretical relation in the latter case is not consistent with reality, in which an infinitely large insulation admittance presents a short circuit across the 3-0 source and a fully effective shunt across the human body. The equivalent circuit is modified, accordingly, to include the internal source resistance in series with the insulation admittance in each phase. Calculations pertaining to the method of personnel protection are continued, to establish the dependence of current on the insulation resistance of the touched phase and thus establish the safe range of this resistance when the resistance as well as the insulation admittance of this phase are different from those of the other two phases and those of the other two phases are equal.

  1. Real time pressure-volume loops in mice using complex admittance: measurement and implications.

    PubMed

    Kottam, Anil T G; Porterfield, John; Raghavan, Karthik; Fernandez, Daniel; Feldman, Marc D; Valvano, Jonathan W; Pearce, John A

    2006-01-01

    Real time left ventricular (LV) pressure-volume (P-V) loops have provided a framework for understanding cardiac mechanics in experimental animals and humans. Conductance measurements have been used for the past 25 years to generate an instantaneous left ventricular (LV) volume signal. The standard conductance method yields a combination of blood and ventricular muscle conductance; however, only the blood signal is used to estimate LV volume. The state of the art techniques like hypertonic saline injection and IVC occlusion, determine only a single steady-state value of the parallel conductance of the cardiac muscle. This is inaccurate, since the cardiac muscle component should vary instantaneously throughout the cardiac cycle as the LV contracts and fills, because the distance from the catheter to the muscle changes. The capacitive nature of cardiac muscle can be used to identify its contribution to the combined conductance signal. This method, in contrast to existing techniques, yields an instantaneous estimate of the parallel admittance of cardiac muscle that can be used to correct the measurement in real time. The corrected signal consists of blood conductance alone. We present the results of real time in vivo measurements of pressure-admittance and pressure-phase loops inside the murine left ventricle. We then use the magnitude and phase angle of the measured admittance to determine pressure volume loops inside the LV on a beat by beat basis. These results may be used to achieve a substantial improvement in the state of the art in this measurement method by eliminating the need for hypertonic saline injection. PMID:17946238

  2. Using an admittance algorithm for bone drilling procedures.

    PubMed

    Accini, Fernando; Díaz, Iñaki; Gil, Jorge Juan

    2016-01-01

    Bone drilling is a common procedure in many types of surgeries, including orthopedic, neurological and otologic surgeries. Several technologies and control algorithms have been developed to help the surgeon automatically stop the drill before it goes through the boundary of the tissue being drilled. However, most of them rely on thrust force and cutting torque to detect bone layer transitions which has many drawbacks that affect the reliability of the process. This paper describes in detail a bone-drilling algorithm based only on the position control of the drill bit that overcomes such problems and presents additional advantages. The implication of each component of the algorithm in the drilling procedure is analyzed and the efficacy of the algorithm is experimentally validated with two types of bones. PMID:26516110

  3. Measuring the complex admittance of a nearly isolated graphene quantum dot

    SciTech Connect

    Zhang, Miao-Lei; Wei, Da; Deng, Guang-Wei; Li, Shu-Xiao; Li, Hai-Ou; Cao, Gang; Tu, Tao; Xiao, Ming; Guo, Guang-Can; Guo, Guo-Ping; Jiang, Hong-Wen

    2014-08-18

    We measured the radio-frequency reflection spectrum of an on-chip reflection line resonator coupled to a graphene double quantum dot (DQD), which was etched almost isolated from the reservoir and reached the low tunnel rate region. The charge stability diagram of DQD was investigated via dispersive phase and magnitude shift of the resonator with a high quality factor. Its complex admittance and low tunnel rate to the reservoir was also determined from the reflected signal of the on-chip resonator. Our method may provide a non-invasive and sensitive way of charge state readout in isolated quantum dots.

  4. Dynamic virtual fixture on the Euclidean group for admittance-type manipulator in deforming environments

    PubMed Central

    2014-01-01

    Background In a deforming anatomic environment, the motion of an instrument suffers from complex geometrical and dynamic constraints, robot assisted minimally invasive surgery therefore requires more sophisticated skills for surgeons. This paper proposes a novel dynamic virtual fixture (DVF) to enhance the surgical operation accuracy of admittance-type medical robotics in the deforming environment. Methods A framework for DVF on the Euclidean Group SE(3) is presented, which unites rotation and translation in a compact form. First, we constructed the holonomic/non-holonomic constraints, and then searched for the corresponded reference to make a distinction between preferred and non-preferred directions. Second, different control strategies are employed to deal with the tasks along the distinguished directions. The desired spatial compliance matrix is synthesized from an allowable motion screw set to filter out the task unrelated components from manual input, the operator has complete control over the preferred directions; while the relative motion between the surgical instrument and the anatomy structures is actively tracked and cancelled, the deviation relative to the reference is compensated jointly by the operator and DVF controllers. The operator, haptic device, admittance-type proxy and virtual deforming environment are involved in a hardware-in-the-loop experiment, human-robot cooperation with the assistance of DVF controller is carried out on a deforming sphere to simulate beating heart surgery, performance of the proposed DVF on admittance-type proxy is evaluated, and both human factors and control parameters are analyzed. Results The DVF can improve the dynamic properties of human-robot cooperation in a low-frequency (0 ~ 40 rad/sec) deforming environment, and maintain synergy of orientation and translation during the operation. Statistical analysis reveals that the operator has intuitive control over the preferred directions, human and the DVF

  5. Admittance Test and Conceptual Study of a CW Positron Source for CEBAF

    SciTech Connect

    Golge, Serkan; Hyde, Charles E.; Freyberger, Arne

    2009-09-02

    A conceptual study of a Continuous Wave (CW) positron production is presented in this paper. The Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Lab (JLAB) operates with a CW electron beam with a well-defined emittance, time structure and energy spread. Positrons created via bremsstrahlung photons in a high-Z target emerge with a large emittance compared to incoming electron beam. An admittance study has been performed at CEBAF to estimate the maximum beam phase space area that can be transported in the LINAC and in the Arcs. A positron source is described utilizing the CEBAF injector electron beam, and directly injecting the positrons into the CEBAF LINAC.

  6. Damage monitoring using fiber optic sensors and by analysing electro-mechanical admittance signatures obtained from piezo sensor

    NASA Astrophysics Data System (ADS)

    Maheshwari, Muneesh; Annamdas, Venu Gopal M.; Pang, John Hock Lye; Tjin, Swee C.; Asundi, Anand

    2015-12-01

    Damage monitoring is the need of the hour in this age of infrastructure. Many methods are being used for damage monitoring in different mechanical and civil structures. Some of them are strain based methods in which abruptly increased strain signifies the presence of damage in the structure. This article focuses on crack monitoring of a fixedfixed beam using fiber optic sensors which can measure strain locally or globally. The two types of fiber optic sensors used in this research are fiber Bragg grating (FBG) and fiber optic polarimetric sensors (FOPS). FBG and FOPS are used for local strain monitoring (at one point only) and global strain monitoring (in the entire specimen) respectively. At the centre of the specimen, a piezoelectric wafer active sensor (PWAS) is also attached. PWAS is used to obtain electromechanical admittance (EMA) signatures. Further, these EMA signatures are analysed to access the damage state in the beam. These multiple smart materials together provide improved information on damages in the specimen which is very valuable for the structural health monitoring (SHM) of the specimen.

  7. Characterization of soil behavior using electromagnetic wave-based technique

    NASA Astrophysics Data System (ADS)

    Dong, Xiaobo

    samples so that the beta value, i.e., the ratio between the conductivities of the sediment and the fluid, is smaller than 1. The beta value is greater than 1 in the Group B samples owing to an overcompensation of surface conduction. Sedimentation behavior of two kaolinite samples with distinct fabric associations is characterized using mechanical and electromagnetic wave-based techniques. The two different fabric formations, the edge-to-face (EF) flocculated structure (i.e., sample A) and the dispersed and deflocculated structure (i.e., sample B), were regulated by changing the pH of the pore fluid and are produced. The anisotropy of shear wave velocity and DC conductivity was not observed in the sediment of sample A because of EF isotropic fabric associations but it was detected in sample B as a result of face-to-face (FF) aggregation. An open card-house structure of the sample A sediment results in a higher relaxation strength of the bulk water, Deltakappaw owing to a higher water content; the smaller Deltakappaw measured in the sample B sediment indicates denser packing. In both samples, sediment consolidation gives rise to a decrease in the bulk-water relaxation strength but an increase in the bound-water relaxation strength owing to increasing particle content. In response to sediment consolidation, the sediment conductivity of sample A continuously decreases because of the reduced contribution from the fluid conductivity. In sample B, the surface conduction via the overlapped double layer overcompensates such a decreased contribution so that the sediment conductivity increases with increasing particle content. The slim-form open-ended coaxial probe is also used to conduct a local dielectric measurement. The measured results, i.e. dielectric relaxation strength of bulk water, Deltakappaw, and the DC conductivity of the saturated sample, sigmamix, are jointly used to characterize the spatial variability of different specimens including glass beads, sand and mica

  8. Localized Gravity/Topography Admittance and Correlation Spectra on Mars: Implications for Regional and Global Evolution

    NASA Technical Reports Server (NTRS)

    McGovern, Patrick J.; Solomon, Sean C.; Smith, David E.; Zuber, Maria T.; Simons, Mark; Wieczorek, Mark A.; Phillips, Roger J.; Neumann, Gregory A.; Aharonson, Oded; Head, James W.

    2002-01-01

    [i] From gravity and topography data collected by the Mars Global Surveyor spacecraft we calculate gravity/topography admittances and correlations in the spectral domain and compare them to those predicted from models of lithospheric flexure. On the basis of these comparisons we estimate the thickness of the Martian elastic lithosphere (T(sub e)) required to support the observed topographic load since the time of loading. We convert T(sub e) to estimates of heat flux and thermal gradient in the lithosphere through a consideration of the response of an elastic/plastic shell. In regions of high topography on Mars (e.g., the Tharsis rise and associated shield volcanoes), the mass-sheet (small-amplitude) approximation for the calculation of gravity from topography is inadequate. A correction that accounts for finite-amplitude topography tends to increase the amplitude of the predicted gravity signal at spacecraft altitudes. Proper implementation of this correction requires the use of radii from the center of mass (collectively known as the planetary shape ) in lieu of topography referenced to a gravitational equipotential. Anomalously dense surface layers or buried excess masses are not required to explain the observed admittances for the Tharsis Montes or Olympus Mons volcanoes when this correction is applied. Derived T, values generally decrease with increasing age of the lithospheric load, in a manner consistent with a rapid decline of mantle heat flux during the Noachian and more modest rates of decline during subsequent epochs.

  9. Distortion product otoacoustic emission suppression tuning and acoustic admittance in human infants: Birth through 6 months

    PubMed Central

    Abdala, Carolina; Keefe, Douglas H.; Oba, Sandra I.

    2009-01-01

    Previous work has reported non-adultlike distortion product otoacoustic emission (DPOAE) suppression in human newborns at f2 =6000 Hz, indicating an immaturity in peripheral auditory function. In this study, DPOAE suppression tuning curves (STCs) were recorded as a measure of cochlear function and acoustic admittance/reflectance (YR) in the ear canal recorded as a measure of middle-ear function, in the same 20 infants at birth and through 6 months of age. DPOAE STCs changed little from birth through 6 months, showing excessively narrow and sharp tuning throughout the test period. In contrast, several middle-ear indices at corresponding frequencies shifted systematically with increasing age, although they also remained non-adultlike at 6 months. Linear correlations were conducted between YR and DPOAE suppression features. Only two correlations out of 76 were significant, and all but three YR variables accounted for <10% of the variance in DPOAE suppression tuning. The strongest correlation was noted between admittance phase at 5700 Hz and STC tip-to-tail (R=0.49). The association between middle-ear variables and DPOAE suppression may be stronger during other developmental time periods. Study of older infants and children is needed to fully define postnatal immaturity of human peripheral auditory function. PMID:17552713

  10. Hole transport characteristics in phosphorescent dye-doped NPB films by admittance spectroscopy

    NASA Astrophysics Data System (ADS)

    Wang, Ying; Chen, Jiangshan; Huang, Jinying; Dai, Yanfeng; Zhang, Zhiqiang; Liu, Su; Ma, Dongge

    2014-05-01

    Admittance spectroscopy is a powerful tool to determine the carrier mobility. The carrier mobility is a significant parameter to understand the behavior or to optimize the organic light-emitting diode or other organic semiconductor devices. Hole transport in phosphorescent dye, bis[2-(9,9-diethyl-9H-fluoren-2-yl)-1-phenyl-1Hbenzoimidazol-N,C3] iridium(acetylacetonate [(fbi)2Ir(acac)]) doped into N,N-diphenyl-N,N-bis(1-naphthylphenyl)-1,1-biphenyl-4,4-diamine (NPB) films was investigated by admittance spectroscopy. The results show that doped (fbi)2Ir(acac) molecules behave as hole traps in NPB, and lower the hole mobility. For thicker films(≳300 nm), the electric field dependence of hole mobility is as expected positive, i.e., the mobility increases exponentially with the electric field. However, for thinner films (≲300 nm), the electric field dependence of hole mobility is negative, i.e., the hole mobility decreases exponentially with the electric field. Physical mechanisms behind the negative field dependence of hole mobility are discussed. In addition, three frequency regions were divided to analyze the behaviors of the capacitance in the hole-only device and the physical mechanism was explained by trap theory and the parasitic capacitance effect.

  11. Characterization of color scanners based on SVR

    NASA Astrophysics Data System (ADS)

    Li, Bin; Zhang, Yi-xin

    2012-01-01

    By researching the principle of colorimetric characterization method and Support Vector Regression (SVR), we analyze the feasibility of nonlinear transformation from scanner RGB color space to CIELAB color space based on SVR and built a new characterization model. Then we use the MATLABR2009a software to make a data simulation experiment to verify the accuracy of this model and figure out the color differences by CIEDE2000 color difference formula. Based on CIEDE2000 color difference formula, the average, the maximum and the minimum color differences of the training set are 1.2376, 2.5593 and 0.2182, the average, the maximum and the minimum color differences of the text set are 1.9318, 4.1421 and 0.4228. From the experimental results, we can make a conclusion that SVR can realize the nonlinear transformation from scanner RGB color space to CIELAB color space and the model satisfies the accuracy of scanner characterization. Therefore, SVR can be used into the color scanner characterization management.

  12. The effect of flying and low humidity on the admittance of the tympanic membrane and middle ear system.

    PubMed

    Morse, Robert Peter

    2013-10-01

    Many passengers experience discomfort during flight because of the effect of low humidity on the skin, eyes, throat, and nose. In this physiological study, we have investigated whether flight and low humidity also affect the tympanic membrane. From previous studies, a decrease in admittance of the tympanic membrane through drying might be expected to affect the buffering capacity of the middle ear and to disrupt automatic pressure regulation. This investigation involved an observational study onboard an aircraft combined with experiments in an environmental chamber, where the humidity could be controlled but could not be made to be as low as during flight. For the flight study, there was a linear relationship between the peak compensated static admittance of the tympanic membrane and relative humidity with a constant of proportionality of 0.00315 mmho/% relative humidity. The low humidity at cruise altitude (minimum 22.7 %) was associated with a mean decrease in admittance of about 20 % compared with measures in the airport. From the chamber study, we further found that a mean decrease in relative humidity of 23.4 % led to a significant decrease in mean admittance by 0.11 mmho [F(1,8) = 18.95, P = 0.002], a decrease of 9.4 %. The order of magnitude for the effect of humidity was similar for the flight and environmental chamber studies. We conclude that admittance changes during flight were likely to have been caused by the low humidity in the aircraft cabin and that these changes may affect the automatic pressure regulation of the middle ear during descent. PMID:23887775

  13. Three-dimensional admittance analysis of lithospheric elastic thickness over the Louisville Ridge

    NASA Astrophysics Data System (ADS)

    Hu, Minzhang; Li, Hui; Shen, Chongyang; Xing, Lelin; Hao, Hongtao

    2016-04-01

    Using bathymetry and altimetric gravity anomalies, a 1° × 1° lithospheric effective elastic thickness ( T e) model over the Louisville Ridge and its adjacent regions is calculated using the moving window admittance technique. For comparison, three bathymetry models are used: general bathymetric charts of the oceans, SIO V15.1, and BAT_VGG. The results show that BAT_VGG is more suitable for calculating T e than the other two models. T e along the Louisville Ridge was re-evaluated. The southeast of the ridge has a medium T e of 10-20 km, while T e increases dramatically seaward of the Tonga-Kermadec trench as a result of the collision of the Pacific and Indo-Australian plates.

  14. Quantum dot admittance probed at microwave frequencies with an on-chip resonator

    NASA Astrophysics Data System (ADS)

    Frey, T.; Leek, P. J.; Beck, M.; Faist, J.; Wallraff, A.; Ensslin, K.; Ihn, T.; Büttiker, M.

    2012-09-01

    We present microwave frequency measurements of the dynamic admittance of a quantum dot tunnel-coupled to a two-dimensional electron gas. The measurements are made via a high-quality 6.75 GHz on-chip resonator capacitively coupled to the dot. The resonator frequency is found to shift both down and up close to conductance resonance of the dot corresponding to a change of sign of the reactance of the system from capacitive to inductive. The observations are consistent with a scattering matrix model. The sign of the reactance depends on the detuning of the dot from conductance resonance and on the magnitude of the tunnel rate to the lead with respect to the resonator frequency. Inductive response is observed on a conductance resonance when tunnel coupling and temperature are sufficiently small compared to the resonator frequency.

  15. Automated clustering-based workload characterization

    NASA Technical Reports Server (NTRS)

    Pentakalos, Odysseas I.; Menasce, Daniel A.; Yesha, Yelena

    1996-01-01

    The demands placed on the mass storage systems at various federal agencies and national laboratories are continuously increasing in intensity. This forces system managers to constantly monitor the system, evaluate the demand placed on it, and tune it appropriately using either heuristics based on experience or analytic models. Performance models require an accurate workload characterization. This can be a laborious and time consuming process. It became evident from our experience that a tool is necessary to automate the workload characterization process. This paper presents the design and discusses the implementation of a tool for workload characterization of mass storage systems. The main features of the tool discussed here are: (1)Automatic support for peak-period determination. Histograms of system activity are generated and presented to the user for peak-period determination; (2) Automatic clustering analysis. The data collected from the mass storage system logs is clustered using clustering algorithms and tightness measures to limit the number of generated clusters; (3) Reporting of varied file statistics. The tool computes several statistics on file sizes such as average, standard deviation, minimum, maximum, frequency, as well as average transfer time. These statistics are given on a per cluster basis; (4) Portability. The tool can easily be used to characterize the workload in mass storage systems of different vendors. The user needs to specify through a simple log description language how the a specific log should be interpreted. The rest of this paper is organized as follows. Section two presents basic concepts in workload characterization as they apply to mass storage systems. Section three describes clustering algorithms and tightness measures. The following section presents the architecture of the tool. Section five presents some results of workload characterization using the tool.Finally, section six presents some concluding remarks.

  16. Multimode model based defect characterization in composites

    NASA Astrophysics Data System (ADS)

    Roberts, R.; Holland, S.; Gregory, E.

    2016-02-01

    A newly-initiated research program for model-based defect characterization in CFRP composites is summarized. The work utilizes computational models of the interaction of NDE probing energy fields (ultrasound and thermography), to determine 1) the measured signal dependence on material and defect properties (forward problem), and 2) an assessment of performance-critical defect properties from analysis of measured NDE signals (inverse problem). Work is reported on model implementation for inspection of CFRP laminates containing delamination and porosity. Forward predictions of measurement response are presented, as well as examples of model-based inversion of measured data for the estimation of defect parameters.

  17. Localized Gravity/Topography Correlation and Admittance Spectra one the Moon

    NASA Astrophysics Data System (ADS)

    Ishihara, Y.; Namiki, N.; Sugita, S.; Matsumoto, K.; Goossens, S.; Araki, H.; Noda, H.; Sasaki, S.; Iwata, T.; Hanada, H.

    2009-04-01

    Lunar surface and structure can be separate into two parts. The lunar near side crust and far side crust differ remarkably in thickness. This difference probably caused by difference of thermal evolution and state (elastic thickness) and catering history on both side. The correlations and admittance between the topography and gravity anomalies provide important information on the level of isostatic compensation of the lithosphere at the geological timescale, and reflect its thermo-mechanical state. Therefore, localized correlation and admittance analysis is one of the most important studies of selenodesy. A global correlation between topography and gravity of the Moon obtained by Clementine and Lunar Prospector missions, respectively, reveals high value at long wavelength and low value at short wavelength. Such characteristics are distinguished from those of the Earth and other terrestrial planets, whose global correlation between topography and gravity is low at long wavelength. The distinct correlation between topography and gravity of the Moon may indicate that the lunar topography is supported by multiple compensation mechanism. Further, an incomplete coverage of Doppler tracking data prior to Kaguya (SELENE) gravity experiment probably contributed to the correlation. Because the Moon is synchronously rotating with its revolution around the Earth, a spacecraft orbiting over the far side is not visible from ground stations. In either case, it is significant to decompose local correlation from global ones in order to investigate internal structure of the Moon from spherical harmonic model of gravity (LP75G [1]) and topography (GLTM-2 [2]). Japanese lunar exploration Kaguya (SELENE) has two kinds of selenodesical experiments. One is RSAT/VRAD (gravity mapping with direct tracking over far-side) experiment and another is Laser ALTimeter (LALT; topography mapping) experiment. These two experiments enable us to conduct localized analysis for the Moon. Therefore we

  18. Numerical calculations for effects of structure of skeletal muscle on frequency-dependence of its electrical admittance and impedance

    NASA Astrophysics Data System (ADS)

    Sekine, Katsuhisa; Yamada, Ayumi; Kageyama, Hitomi; Igarashi, Takahiro; Yamamoto, Nana; Asami, Koji

    2015-06-01

    Numerical calculations were carried out by the finite difference method using three-dimensional models to examine effects of the structure of skeletal muscle on the frequency-dependence of its electrical admittance Y and impedance Z in transversal and longitudinal directions. In the models, the muscle cell was represented by a rectangular solid surrounded by a smooth surface membrane, and the cells were assumed to be distributed periodically. The width of the cross section of the cell, thickness of the intercellular medium, and the relative permittivities and the conductivities of the cell interior, the intercellular medium and the surface membrane were changed. Based on the results of the calculations, reported changes in Y and Z of the muscles from 1 kHz to 1 MHz were analyzed. The analyses revealed that a decreased cell radius was reasonable to explain the Y and Z of the muscles of immature rats, rats subjected to sciatic nerve crush at chronic stage and the amyotrophic lateral sclerosis (ALS) mice. Changes in Y and Z due to the sciatic nerve crush at acute stage were attributable to the decreased cell radius, the increased space between the cells, the increased permittivity of the surface membrane and the increased conductivity of the cell interior. The changes in Z due to contraction were explained by the changes in the cell radius, and the conductivities of the cell interior and the intercellular medium. The changes in Z of meat due to aging were compared with the effects of the increase in the conductivity of the surface membrane.

  19. Thermal stress characterization using the impedance-based structural health monitoring system

    NASA Astrophysics Data System (ADS)

    Zhu, Xuan; Lanza di Scalea, Francesco; Fateh, Mahmood

    2016-04-01

    Structural health monitoring (SHM) has attracted researchers' interests for the past two decades to reinforce the maintenance of the aging infrastructure systems all over the world. As one of the potential solutions, the electro-mechanical impedance (EMI) method was introduced in the early 1990s and has a great number of potential applications in the SHM of civil, mechanical and aerospace industries. This paper studied the impedance-based technique with the presence of environmental/operational variability, especially the influences of temperature and uniaxial stress on the admittance signature-based features. A comprehensive analytical model is established and provides satisfactory agreements with the experimental results. The stress and temperature sensitivities of all the proposed features are quantified using the experimental measurements, with discussions on their advantages and disadvantages. The final results illustrate that the EMI method can potentially provide effective measure for thermal stress.

  20. Use of Admittance-Wall Models in Analysis of Radiating Line Antennas

    NASA Astrophysics Data System (ADS)

    Tammen, David John

    This thesis describes the development of analytical models for two radiating line antenna structures: the traveling -wave microstrip antenna and the Annular Sector Radiating Line (ANSERLIN) antenna. The models provide data and insights into the operation of the antennas without requiring large amounts of computation. It was shown that the general characteristics of the radiation patterns of ANSERLIN elements can be obtained using only a small number of circularly polarized spherical modes in the field expansion. A first -order model is obtained by solving for the fields of a closed waveguide with perfect electric conducting (PEC) top and bottom walls and perfect magnetic conducting (PMC) side walls. The propagation constant obtained from these fields of the closed waveguide is then used in the equivalent magnetic current filaments to obtain the radiated fields. Use of the propagation constant of the closed waveguide fields does not include the fringing and radiation behavior. A second-order model was developed in which the radiation loss and fringing fields are included by putting a small complex admittance on the side walls rather than having PMC side walls. Two formulations were developed to include the radiation loss in the representation: a coupled-mode formulation and an eigenvalue formulation. The coupled -mode formulation, which is similar to that described by Schelkunoff for a waveguide with lossy conductors, is used to obtain the complex-valued propagation constant. In the eigenvalue formulation, the eigenvalues obtained from the solution of the characteristic equation of the waveguide with admittance side walls are used to obtain the complex -valued propagation constant. This complex-valued propagation constant, which includes the fringing and radiation behavior, is then used in the equivalent magnetic current filaments to obtain the radiated fields. Good agreement was found between measured results and results computed using the eigenvalue formulation

  1. Characterization and supply of coal based fuels

    SciTech Connect

    Not Available

    1992-06-01

    Studies and data applicable for fuel markets and coal resource assessments were reviewed and evaluated to provide both guidelines and specifications for premium quality coal-based fuels. The fuels supplied under this contract were provided for testing of advanced combustors being developed under Pittsburgh Energy Technology Center (PETC) sponsorship for use in the residential, commercial and light industrial (RCLI) market sectors. The requirements of the combustor development contractors were surveyed and periodically updated to satisfy the evolving needs based on design and test experience. Available coals were screened and candidate coals were selected for further detailed characterization and preparation for delivery. A team of participants was assembled to provide fuels in both coal-water fuel (CWF) and dry ultrafine coal (DUC) forms. Information about major US coal fields was correlated with market needs analysis. Coal fields with major reserves of low sulfur coal that could be potentially amenable to premium coal-based fuels specifications were identified. The fuels requirements were focused in terms of market, equipment and resource constraints. With this basis, the coals selected for developmental testing satisfy the most stringent fuel requirements and utilize available current deep-cleaning capabilities.

  2. An Admittance Survey of Large Volcanoes on Venus: Implications for Volcano Growth

    NASA Technical Reports Server (NTRS)

    Brian, A. W.; Smrekar, S. E.; Stofan, E. R.

    2004-01-01

    Estimates of the thickness of the venusian crust and elastic lithosphere are important in determining the rheological and thermal properties of Venus. These estimates offer insights into what conditions are needed for certain features, such as large volcanoes and coronae, to form. Lithospheric properties for much of the large volcano population on Venus are not well known. Previous studies of elastic thickness (Te) have concentrated on individual or small groups of edifices, or have used volcano models and fixed values of Te to match with observations of volcano morphologies. In addition, previous studies use different methods to estimate lithospheric parameters meaning it is difficult to compare their results. Following recent global studies of the admittance signatures exhibited by the venusian corona population, we performed a similar survey into large volcanoes in an effort to determine the range of lithospheric parameters shown by these features. This survey of the entire large volcano population used the same method throughout so that all estimates could be directly compared. By analysing a large number of edifices and comparing our results to observations of their morphology and models of volcano formation, we can help determine the controlling parameters that govern volcano growth on Venus.

  3. Universal Impedance, Admittance and Scattering Fluctuations in Quantum-chaotic Systems

    NASA Astrophysics Data System (ADS)

    Hemmady, Sameer

    2006-03-01

    We experimentally investigate fluctuations in the eigenvalues of the impedance, admittance and scattering matrices of wave chaotic systems using a microwave analog of a quantum chaotic infinite square well potential. We consider a 2-D, time-reversal symmetric chaotic microwave resonator driven by two non-ideally coupled ports. The system-specific coupling effects are removed using the measured radiation impedance matrix (3pt<->Z Rad) [1] of the two ports. A normalized impedance matrix (3pt<->z ) is thus obtained, and the Probability Density Function (PDF) of its eigenvalues is predicted to be universal depending only on the cavity loss. We observe remarkable agreement between the statistical properties of 3pt<->z and 3pt<->y =3pt<->z -1 for all degrees of loss, which is in accordance with [1, 2] and Random Matrix Theory (RMT). We compare the joint PDF of the eigenphases of the normalized scattering matrix (3pt<->s ) with that obtained from RMT for varying degrees of loss. We study the joint PDF of the eigenvalues of 3pt<->s 3pt<->s ^ and find good agreement with [3]. [1] X. Zheng, et al., -- Electromagnetics (in press); condmat/0408317; S. Hemmady, et al., Phys. Rev. Lett. 94, 014102 (2005).[2] Y. V. Fyodorov, et al.,-- condmat/0507016.[3] P. W. Brouwer and C. W. J Beenakker -- PRB 55, 4695 (1997). Work supported by DOD MURI AFOSR Grant F496200110374, DURIP Grants FA95500410295 and FA95500510240.

  4. Universal Impedance, Admittance and Scattering Fluctuations in Quantum-chaotic Systems.

    NASA Astrophysics Data System (ADS)

    Hemmady, Sameer; Zheng, Xing; Antonsen, Thomas; Ott, Edward; Anlage, Steven M.

    2006-03-01

    We experimentally investigate fluctuations in the eigenvalues of the impedance, admittance and scattering matrices of wave chaotic systems using a microwave analog of a quantum chaotic infinite square well potential. We consider a 2-D, time-reversal symmetric chaotic microwave resonator driven by two non-ideally coupled ports. The system-specific coupling effects are removed using the measured radiation impedance matrix (3pt<->Z Rad) [1] of the two ports. A normalized impedance matrix (3pt<->z ) is thus obtained, and the Probability Density Function (PDF) of its eigenvalues is predicted to be universal depending only on the cavity loss. We observe remarkable agreement between the statistical properties of 3pt<->z and 3pt<->y =3pt<->z -1 for all degrees of loss, which is in accordance with [1, 2] and Random Matrix Theory (RMT). We compare the joint PDF of the eigenphases of the normalized scattering matrix (3pt<->s ) with that obtained from RMT for varying degrees of loss. We study the joint PDF of the eigenvalues of 3pt<->s 3pt<->s ^ and find good agreement with [3]. [1] X. Zheng, et al., -- Electromagnetics (in press); condmat/0408317; S. Hemmady, et al., Phys. Rev. Lett. 94, 014102 (2005).[2] Y. V. Fyodorov, et al.,-- condmat/0507016.[3] P. W. Brouwer and C. W. J Beenakker -- PRB 55, 4695 (1997). Work supported by DOD MURI AFOSR Grant F496200110374, DURIP Grants FA95500410295 and FA95500510240.

  5. Model-based target and background characterization

    NASA Astrophysics Data System (ADS)

    Mueller, Markus; Krueger, Wolfgang; Heinze, Norbert

    2000-07-01

    Up to now most approaches of target and background characterization (and exploitation) concentrate solely on the information given by pixels. In many cases this is a complex and unprofitable task. During the development of automatic exploitation algorithms the main goal is the optimization of certain performance parameters. These parameters are measured during test runs while applying one algorithm with one parameter set to images that constitute of image domains with very different domain characteristics (targets and various types of background clutter). Model based geocoding and registration approaches provide means for utilizing the information stored in GIS (Geographical Information Systems). The geographical information stored in the various GIS layers can define ROE (Regions of Expectations) and may allow for dedicated algorithm parametrization and development. ROI (Region of Interest) detection algorithms (in most cases MMO (Man- Made Object) detection) use implicit target and/or background models. The detection algorithms of ROIs utilize gradient direction models that have to be matched with transformed image domain data. In most cases simple threshold calculations on the match results discriminate target object signatures from the background. The geocoding approaches extract line-like structures (street signatures) from the image domain and match the graph constellation against a vector model extracted from a GIS (Geographical Information System) data base. Apart from geo-coding the algorithms can be also used for image-to-image registration (multi sensor and data fusion) and may be used for creation and validation of geographical maps.

  6. Force Control and Nonlinear Master-Slave Force Profile to Manage an Admittance Type Multi-Fingered Haptic User Interface

    SciTech Connect

    Anthony L. Crawford

    2012-08-01

    Natural movements and force feedback are important elements in using teleoperated equipment if complex and speedy manipulation tasks are to be accomplished in remote and/or hazardous environments, such as hot cells, glove boxes, decommissioning, explosives disarmament, and space to name a few. In order to achieve this end the research presented in this paper has developed an admittance type exoskeleton like multi-fingered haptic hand user interface that secures the user’s palm and provides 3-dimensional force feedback to the user’s fingertips. Atypical to conventional haptic hand user interfaces that limit themselves to integrating the human hand’s characteristics just into the system’s mechanical design this system also perpetuates that inspiration into the designed user interface’s controller. This is achieved by manifesting the property differences of manipulation and grasping activities as they pertain to the human hand into a nonlinear master-slave force relationship. The results presented in this paper show that the admittance-type system has sufficient bandwidth that it appears nearly transparent to the user when the user is in free motion and when the system is subjected to a manipulation task, increased performance is achieved using the nonlinear force relationship compared to the traditional linear scaling techniques implemented in the vast majority of systems.

  7. MOLA-Based Landing Site Characterization

    NASA Technical Reports Server (NTRS)

    Duxbury, T. C.; Ivanov, A. B.

    2001-01-01

    The Mars Global Surveyor (MGS) Mars Orbiter Laser Altimeter (MOLA) data provide the basis for site characterization and selection never before possible. The basic MOLA information includes absolute radii, elevation and 1 micrometer albedo with derived datasets including digital image models (DIM's illuminated elevation data), slopes maps and slope statistics and small scale surface roughness maps and statistics. These quantities are useful in downsizing potential sites from descent engineering constraints and landing/roving hazard and mobility assessments. Slope baselines at the few hundred meter level and surface roughness at the 10 meter level are possible. Additionally, the MOLA-derived Mars surface offers the possibility to precisely register and map project other instrument datasets (images, ultraviolet, infrared, radar, etc.) taken at different resolution, viewing and lighting geometry, building multiple layers of an information cube for site characterization and selection. Examples of direct MOLA data, data derived from MOLA and other instruments data registered to MOLA arc given for the Hematite area.

  8. Chemical characterization of carbohydrate-based biosurfactants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    High-yield, glycolipid-based biosurfactants are of increasing interest for use in environmentally benign cleaning or emulsifying agents. We have developed a MALDI-TOF/MS screen for the rapid analysis of several types of biosurfactants, including various acylated rhamnolipids in Pseudomonas extracts...

  9. Characterization of ceria-based SOFCs

    SciTech Connect

    Doshi, R.; Roubort, J.; Krumpelt, M.

    1996-12-31

    Solid Oxide Fuel Cells (SOFCs) operating at low temperatures (500-700 C) offer many advantages over conventional zirconia-based fuel cells operating at higher temperatures. Cathode performance is being improved by using better materials and/or microstructures. Fabrication of thin dense electrolytes is also necessary to achieve high cell performances.

  10. [Quaternion-based Characterization of Protein α Helix].

    PubMed

    Xu, Yonghong; Chu, Zefei

    2016-02-01

    This paper proposes a method based on quaternion for characterization a helix of proteins. The method defines the parameter called Quaternion Helix Axis Spherical Distance (QHASD) on the basis of mapping protein Cα frames' helical axis onto a unit sphere, and uses QHASD to characterize the a helix of the protein secondary structure. Application of this method has been verified based on the PDBselect database, with an a helix characterization accuracy of 91.7%. This method possesses significant advantages of high detection accuracy, low computation and clear geometric significance. PMID:27382757

  11. Characterization of electrospun lignin based carbon fibers

    NASA Astrophysics Data System (ADS)

    Poursorkhabi, Vida; Mohanty, Amar; Misra, Manjusri

    2015-05-01

    The production of lignin fibers has been studied in order to replace the need for petroleum based precursors for carbon fiber production. In addition to its positive environmental effects, it also benefits the economics of the industries which cannot take advantage of carbon fiber properties because of their high price. A large amount of lignin is annually produced as the byproduct of paper and growing cellulosic ethanol industry. Therefore, finding high value applications for this low cost, highly available material is getting more attention. Lignin is a biopolymer making about 15 - 30 % of the plant cell walls and has a high carbon yield upon carbonization. However, its processing is challenging due to its low molecular weight and also variations based on its origin and the method of separation from cellulose. In this study, alkali solutions of organosolv lignin with less than 1 wt/v% of poly (ethylene oxide) and two types of lignin (hardwood and softwood) were electrospun followed by carbonization. Different heating programs for carbonization were tested. The carbonized fibers had a smooth surface with an average diameter of less than 5 µm and the diameter could be controlled by the carbonization process and lignin type. Scanning electron microscopy (SEM) was used to study morphology of the fibers before and after carbonization. Thermal conductivity of a sample with amorphous carbon was 2.31 W/m.K. The electrospun lignin carbon fibers potentially have a large range of application such as in energy storage devices and water or gas purification systems.

  12. Characterization of ceria-based SOFCs

    SciTech Connect

    Doshi, R.; Routbort, J.; Krumpelt, M.

    1996-12-31

    Solid Oxide Fuel Cells (SOFCs) operating at low temperatures (500-700{degrees}C) offer many advantages over the conventional zirconia-based fuel cells operating at higher temperatures. Reduced operating temperatures result in: (1) Application of metallic interconnects with reduced oxidation problems (2) Reduced time for start-up and lower energy consumption to reach operating temperatures (3) Increased thermal cycle ability for the cell structure due to lower thermal stresses of expansion mismatches. While this type of fuel cell may be applied to stationary applications, mobile applications require the ability for rapid start-up and frequent thermal cycling. Ceria-based fuel cells are currently being developed in the U.K. at Imperial College, Netherlands at ECN, and U.S.A. at Ceramatec. The cells in each case are made from a doped ceria electrolyte and a La{sub 1-x}Sr{sub x}Co{sub 1-y}Fe{sub y}O{sub 3} cathode.

  13. Characterization of polyacrylamide based monolithic columns.

    PubMed

    Plieva, Fatima M; Andersson, Jonatan; Galaev, Igor Yu; Mattiasson, Bo

    2004-07-01

    Supermacroporous monolithic polyacrylamide (pAAm)-based columns have been prepared by radical cryo-copolymerization (copolymerization in the moderately frozen system) of acrylamide with functional co-monomer, allyl glycidyl ether (AGE), and cross-linker N,N'-methylene-bis-acrylamide (MBAAm) directly in glass columns (ID 10 mm). The monolithic columns have uniform supermacroporous sponge-like structure with interconnected supermacropores of pore size 5-100 microm. The monoliths can be dried and stored in the dry state. High mechanical stability of the monoliths allowed sterilization by autoclaving. Column-to-column reproducibility of pAAm-monoliths was demonstrated on 5 monolithic columns from different batches prepared under the same cryostructuration conditions. PMID:15354560

  14. Characterization of electrospun lignin based carbon fibers

    SciTech Connect

    Poursorkhabi, Vida; Mohanty, Amar; Misra, Manjusri

    2015-05-22

    The production of lignin fibers has been studied in order to replace the need for petroleum based precursors for carbon fiber production. In addition to its positive environmental effects, it also benefits the economics of the industries which cannot take advantage of carbon fiber properties because of their high price. A large amount of lignin is annually produced as the byproduct of paper and growing cellulosic ethanol industry. Therefore, finding high value applications for this low cost, highly available material is getting more attention. Lignin is a biopolymer making about 15 – 30 % of the plant cell walls and has a high carbon yield upon carbonization. However, its processing is challenging due to its low molecular weight and also variations based on its origin and the method of separation from cellulose. In this study, alkali solutions of organosolv lignin with less than 1 wt/v% of poly (ethylene oxide) and two types of lignin (hardwood and softwood) were electrospun followed by carbonization. Different heating programs for carbonization were tested. The carbonized fibers had a smooth surface with an average diameter of less than 5 µm and the diameter could be controlled by the carbonization process and lignin type. Scanning electron microscopy (SEM) was used to study morphology of the fibers before and after carbonization. Thermal conductivity of a sample with amorphous carbon was 2.31 W/m.K. The electrospun lignin carbon fibers potentially have a large range of application such as in energy storage devices and water or gas purification systems.

  15. [Synchrotron-based characterization methods applied to ancient materials (I)].

    PubMed

    Anheim, Étienne; Thoury, Mathieu; Bertrand, Loïc

    2015-12-01

    This article aims at presenting the first results of a transdisciplinary research programme in heritage sciences. Based on the growing use and on the potentialities of micro- and nano-characterization synchrotron-based methods to study ancient materials (archaeology, palaeontology, cultural heritage, past environments), this contribution will identify and test conceptual and methodological elements of convergence between physicochemical and historical sciences. PMID:25200450

  16. DEVELOPMENT OF A WATERSHED-BASED MERCURY POLLUTION CHARACTERIZATION SYSTEM

    EPA Science Inventory

    To investigate total mercury loadings to streams in a watershed, we have developed a watershed-based source quantification model ? Watershed Mercury Characterization System. The system uses the grid-based GIS modeling technology to calculate total soil mercury concentrations and ...

  17. Dielectric relaxation in hafnium oxide: A study of transient currents and admittance spectroscopy in HfO2 metal-insulator-metal devices

    NASA Astrophysics Data System (ADS)

    Mannequin, C.; Gonon, P.; Vallée, C.; Bsiesy, A.; Grampeix, H.; Jousseaume, V.

    2011-11-01

    Dielectric relaxation is studied in 10 nm HfO2 thin films which are deposited by atomic layer deposition on TiN and Pt electrodes. Transient currents are recorded from 10-3 s to 10 s, as a function of bias (0.1 V to 1 V) and temperature (20 °C to 180 °C). A Curie-von Schweidler law is observed, I = Q0/tα. The power law exponent α is constant with bias and strongly depends on the temperature (varying in the 0.65-1.05 range, with a peak at 75 °C). The amplitude Q0 is described by a relation of the form Q0 = C0Vβ, where the factor C0 is weakly activated and the exponent β varies with temperature (in the 0.9-1.5 range as T varies). Transient currents are discussed along with tunneling based models from the literature. To complement transient current experiments, admittance spectroscopy (conductance G and capacitance C) is performed at low frequencies, from 0.01 Hz to 10 kHz. The dispersion law of the conductance is of the form G ˜ ωs. The capacitance is the sum of two terms, a non-dispersive term (C∞) and a low-frequency dispersive term, CLF ˜ ω-n. The critical exponents s and n verify s ≈ α and n ≈ 1-α. At room temperature, the dielectric constant is expressed as ɛ' = Δɛ' f-n+ ɛ'∞, where ɛ'∞ = 11.1, n ≈ 0.2/0.3 (Pt/TiN), and Δɛ' ≈ 1.5/0.7 (Pt/TiN).

  18. Synthesis and characterization of Schiff's bases of sulfamethoxazole

    PubMed Central

    2014-01-01

    Background Schiff's bases are excellent ligands which are synthesized from the condensation of primary amines with carbonyl groups. Findings The classical reaction for the synthesis of Schiff's bases in an ethanolic solution and glacial acetic acid as a catalyst was followed in the synthesis of substituted sulfamethoxazole compounds. Conclusions Some Schiff's bases containing sulfamethoxazole nucleus have been synthesized and characterized. The present compounds are hoped to be applied in the photostability of PVC. PMID:24576663

  19. Characterizing Task-Based OpenMP Programs

    PubMed Central

    Muddukrishna, Ananya; Jonsson, Peter A.; Brorsson, Mats

    2015-01-01

    Programmers struggle to understand performance of task-based OpenMP programs since profiling tools only report thread-based performance. Performance tuning also requires task-based performance in order to balance per-task memory hierarchy utilization against exposed task parallelism. We provide a cost-effective method to extract detailed task-based performance information from OpenMP programs. We demonstrate the utility of our method by quickly diagnosing performance problems and characterizing exposed task parallelism and per-task instruction profiles of benchmarks in the widely-used Barcelona OpenMP Tasks Suite. Programmers can tune performance faster and understand performance tradeoffs more effectively than existing tools by using our method to characterize task-based performance. PMID:25860023

  20. Synthesis and Characterization of Metal Complexes with Schiff Base Ligands

    ERIC Educational Resources Information Center

    Wilkinson, Shane M.; Sheedy, Timothy M.; New, Elizabeth J.

    2016-01-01

    In order for undergraduate laboratory experiments to reflect modern research practice, it is essential that they include a range of elements, and that synthetic tasks are accompanied by characterization and analysis. This intermediate general chemistry laboratory exercise runs over 2 weeks, and involves the preparation of a Schiff base ligand and…

  1. Modeling and analysis of the admittance characteristics of n+ metal-oxide-semiconductor capacitors with oxide and interface states - Gd0.25Ga0.15O0.6/Ga2O3 on In0.53Ga0.47As

    NASA Astrophysics Data System (ADS)

    Paterson, G. W.; Holland, M. C.; Thayne, I. G.; Long, A. R.

    2012-04-01

    The 300-K admittance characteristics of n+ In0.53Ga0.47As MOS capacitors with a dielectric stack of Gd0.25Ga0.15O0.6/Ga2O3 in as-grown condition are examined in detail and compared to an oxide trap model that we previously introduced. The model explains many of the observed features not contained in the interface state model. By fitting the model to experimental data, we extract a distribution of defect states in space and energy within the oxide and at the oxide/semiconductor interface separately. Oxide states are the dominant defects over a wide range of energy. The defect state densities are not subject to the usual resolution limits of conventional analyses. Using this approach, it is possible to characterize relatively rapidly a wide range of energies at a single temperature without the need for reaching the low or high limits of frequency. The implications for the conventional interface state density (Dit) extraction techniques are explored. It is shown how oxide states can affect the extraction of sample parameters, particularly the insulator capacitance, and can result in a range of extracted Dit values. We believe these contribute to the wide range of Dit reported in the literature from similar admittance characteristics of a number of oxides on In0.53Ga0.47As.

  2. A new estimate of the effective elastic thickness of the Canadian shield from admittance analyses using the wavelet transform, and models of flexure and mantle convection

    NASA Astrophysics Data System (ADS)

    Kirby, J. F.; Swain, C. J.

    2013-12-01

    The flexural rigidity of the Earth's cratonic regions is a topic of much controversy. While many studies have suggested that cratons possess high elastic strength, others maintain that the continental lithosphere is everywhere weak. In this study we focus on the Canadian shield, and show that perceived evidence for weak cratonic lithosphere is compromised by shortcomings of the spectral analysis technique. Here we compare estimates of the admittance between free-air gravity and topography in the spectral domain from wavelet and multitaper methods. We apply particular attention to their long wavelength values, since it is here that the signals from mantle convection, glacial isostatic adjustment (GIA) and flexure are often present together. Our results show that, when used with certain parameter values, the multitaper method has a comparatively poor resolution at long wavelengths, and hence is not always able to distinguish between the harmonics due to convection and flexural processes. This renders it unreliable for estimating the flexural rigidity. We then show that the wavelet method does have the requisite properties to make this distinction, since it is able to correctly resolve a low-admittance dip at long wavelengths in both synthetic and real data. When the observed wavelet admittance of the Canadian shield is inverted against the predictions of a combined flexural, convection and GIA model, we find that the shield possesses a core of high effective elastic thickness (Te), greater than 118 km to 95% confidence, located to the immediate south-west of Hudson Bay.

  3. Elastic characterization of nanoporous gold foams using laser based ultrasonics.

    PubMed

    Ahn, Phillip; Balogun, Oluwaseyi

    2014-03-01

    A resonance based laser ultrasonics technique is explored for the characterization of low density nanoporous gold foams. Laser generated zero group velocity (ZGV) lamb waves are measured in the foams using a Michelson interferometer. The amplitude spectra obtained from the processed time-domain data are analyzed using a theoretical model from which the foam Young's modulus and Poisson's ratio are obtained. The technique is non-contact and nondestructive, and the ZGV resonance modes are spatially localized, allowing for spatial mapping of the bulk sample properties. The technique may be suitable for process control monitoring and mechanical characterization of low density nanoporous structures. PMID:24524154

  4. An admittance study of the Reykjanes Ridge and elevated plateaux between the Charlie-Gibbs and Senja fracture zones

    NASA Astrophysics Data System (ADS)

    Heller, Daniel A.; Marquart, Gabriele

    2002-01-01

    The North Atlantic between the Charlie-Gibbs and Senja Fracture Zones shows a number of oceanic plateaux, continental fragments and unusual mid-oceanic ridges, the Reykjanes Ridges and the Iceland Plateau being the most prominent ones. While rifted continental fragments and marginal volcanic plateaux have been formed during the initial formation process of the North Atlantic, others, such as the Reykjanes Ridge and plume-related plateaux such as Iceland and possibly also Jan Mayen, are still under development. By studying the ratio of geoid to topography in the long-wavelength range for these regions of elevated topography and comparing the results with theoretical models of crustal loading and subsurface thermal uplift we can show that the Rockall Bank and the Vøring Plateau are compensated by a thick crust alone, while the Iceland Plateau, the outer Faeroe Plateau and the Jan Mayen Block have a strong component of deeply situated mass anomalies. The admittance, the spectral ratio of geoid to topography, for a number of profiles across the Reykjanes Ridge clearly indicates a decrease in compensation depth with distance from Iceland. This strengthens the argument for a mass flux from the Iceland Plume into the Reykjanes Ridge.

  5. Ear-canal acoustic admittance and reflectance effects in human neonates. I. Predictions of otoacoustic emission and auditory brainstem responses

    NASA Astrophysics Data System (ADS)

    Keefe, Douglas H.; Zhao, Fei; Neely, Stephen T.; Gorga, Michael P.; Vohr, Betty R.

    2003-01-01

    This report describes the extent to which ear-canal acoustic admittance and energy reflectance (YR) in human neonates (1) predict otoacoustic emission (OAE) levels and auditory brainstem response (ABR) latencies, and (2) classify OAE and ABR responses as present or absent. Analyses are reported on a subset of ears in which hearing screening measurements were obtained previously [Norton et al., Ear. Hear. 21, 348-356 (2000a)]. Tests on 1405 ears included YR, distortion-product OAEs, transient-evoked OAEs, and ABR. Principal components analysis reduced the 33 YR variables to 5-7 factors. OAE levels decreased and ABR latencies increased with increasing high-frequency energy reflectance. Up to 28% of the variance in OAE levels and 12% of the variance in ABR wave-V latencies were explained by these factors. Thus, the YR response indirectly encodes information on inter-ear variations in forward and reverse middle-ear transmission. The YR factors classify OAEs with an area under the relative operating characteristic (ROC) curve as high as 0.79, suggesting that middle-ear dysfunction is partly responsible for the inability to record OAEs in some ears. The YR factors classified ABR responses less well, with ROC areas of 0.64 for predicting wave-V latency and 0.56 for predicting Fsp.

  6. LOPES II--Design and Evaluation of an Admittance Controlled Gait Training Robot With Shadow-Leg Approach.

    PubMed

    Meuleman, Jos; van Asseldonk, Edwin; van Oort, Gijs; Rietman, Hans; van der Kooij, Herman

    2016-03-01

    Robotic gait training is gaining ground in rehabilitation. Room for improvement lies in reducing donning and doffing time, making training more task specific and facilitating active balance control, and by allowing movement in more degrees of freedom. Our goal was to design and evaluate a robot that incorporates these improvements. LOPES II uses an end-effector approach with parallel actuation and a minimum amount of clamps. LOPES II has eight powered degrees of freedom (hip flexion/extension, hip abduction/adduction, knee flexion/extension, pelvis forward/aft and pelvis mediolateral). All other degrees of freedom can be left free and pelvis frontal- and transversal rotation can be constrained. Furthermore arm swing is unhindered. The end-effector approach eliminates the need for exact alignment, which results in a donning time of 10-14 min for first-time training and 5-8 min for recurring training. LOPES II is admittance controlled, which allows for the control over the complete spectrum from low to high impedance. When the powered degrees of freedom are set to minimal impedance, walking in the device resembles free walking, which is an important requisite to allow task-specific training. We demonstrated that LOPES II can provide sufficient support to let severely affected patients walk and that we can provide selective support to impaired aspects of gait of mildly affected patients. PMID:26731771

  7. Combustion characterization of beneficiated coal-based fuels

    SciTech Connect

    Chow, O.K.; Levasseur, A.A.

    1995-11-01

    The Pittsburgh Energy Technology Center (PETC) of the U.S. Department of Energy is sponsoring the development of advanced coal-cleaning technologies aimed at expanding the use of the nation`s vast coal reserves in an environmentally and economically acceptable manner. Because of the lack of practical experience with deeply beneficiated coal-based fuels, PETC has contracted Combustion Engineering, Inc. to perform a multi-year project on `Combustion Characterization of Beneficiated Coal-Based Fuels.` The objectives of this project include: (1) the development of an engineering data base which will provide detailed information on the properties of Beneficiated Coal-Based Fuels (BCs) influencing combustion, ash deposition, ash erosion, particulate collection, and emissions; and (2) the application of this technical data base to predict the performance and economic impacts of firing the BCFs in various commercial boiler designs.

  8. Characterization of spectral irradiance system based on a filter radiometer

    NASA Astrophysics Data System (ADS)

    Lima, M. S.; Silva, T. F.; Duarte, I.; Correa, J. S.; Viana, D.; Sousa, W. A.; Almeida, G. B.; Couceiro, I. B.

    2016-07-01

    The spectral irradiance scale has been realized recently. It is based on a filter radiometer that was mounted and characterized. The optical system was assembled and the procedures of the methodology were defined, including the mounting of FEL lamp jig, alignment of the optical system, calibration of the instruments and optical devices used on the experimental system. The main uncertainty components were evaluated and the preliminary uncertainty budget of the spectral irradiance system is presented.

  9. Estimation of Ultrafilter Performance Based on Characterization Data

    SciTech Connect

    Peterson, Reid A.; Geeting, John GH; Daniel, Richard C.

    2007-08-02

    Due to limited availability of test data with actual waste samples, a method was developed to estimate expected filtration performance based on physical characterization data for the Hanford Waste Treatment and Immobilization Plant. A test with simulated waste was analyzed to demonstrate that filtration of this class of waste is consistent with a concentration polarization model. Subsequently, filtration data from actual waste samples were analyzed to demonstrate that centrifuged solids concentrations provide a reasonable estimate of the limiting concentration for filtration.

  10. Formulation and Characterization of ADN-Based Liquid Monopropellants

    NASA Astrophysics Data System (ADS)

    Wingborg, N.; Eldsäter, C.; Skifs, H.

    2004-10-01

    Ternary ionic solutions are promising green propellants to replace monopropellant hydrazine. Ammonium dinitramide, ADN, is well suited as oxidizer in these propellants due to its high solubility. This paper presents the formulation of different ADN-based liquid monopropellants and the characterization of their properties such as stability, density, viscosity and sensitivity. To be able to use ADN-based monopropellants for propulsion applications, ADN must be produced in a way to minimize the effect on the environment and in sufficient quantities. This paper thus also briefly presents the industrial production of ADN in Sweden and the efforts made to optimize the process.

  11. Dosage-based parameters for characterization of puff dispersion results.

    PubMed

    Berbekar, Eva; Harms, Frank; Leitl, Bernd

    2015-01-01

    A set of parameters is introduced to characterize the dispersion of puff releases based on the measured dosage. These parameters are the dosage, peak concentration, arrival time, peak time, leaving time, ascent time, descent time and duration. Dimensionless numbers for the scaling of the parameters are derived from dimensional analysis. The dimensionless numbers are tested and confirmed based on a statistically representative wind tunnel dataset. The measurements were carried out in a 1:300 scale model of the Central Business District in Oklahoma City. Additionally, the effect of the release duration on the puff parameters is investigated. PMID:25278155

  12. Cement-based materials' characterization using ultrasonic attenuation

    NASA Astrophysics Data System (ADS)

    Punurai, Wonsiri

    The quantitative nondestructive evaluation (NDE) of cement-based materials is a critical area of research that is leading to advances in the health monitoring and condition assessment of the civil infrastructure. Ultrasonic NDE has been implemented with varying levels of success to characterize cement-based materials with complex microstructure and damage. A major issue with the application of ultrasonic techniques to characterize cement-based materials is their inherent inhomogeneity at multiple length scales. Ultrasonic waves propagating in these materials exhibit a high degree of attenuation losses, making quantitative interpretations difficult. Physically, these attenuation losses are a combination of internal friction in a viscoelastic material (ultrasonic absorption), and the scattering losses due to the material heterogeneity. The objective of this research is to use ultrasonic attenuation to characterize the microstructure of heterogeneous cement-based materials. The study considers a real, but simplified cement-based material, cement paste---a common bonding matrix of all cement-based composites. Cement paste consists of Portland cement and water but does not include aggregates. First, this research presents the findings of a theoretical study that uses a set of existing acoustics models to quantify the scattered ultrasonic wavefield from a known distribution of entrained air voids. These attenuation results are then coupled with experimental measurements to develop an inversion procedure that directly predicts the size and volume fraction of entrained air voids in a cement paste specimen. Optical studies verify the accuracy of the proposed inversion scheme. These results demonstrate the effectiveness of using attenuation to measure the average size, volume fraction of entrained air voids and the existence of additional larger entrapped air voids in hardened cement paste. Finally, coherent and diffuse ultrasonic waves are used to develop a direct

  13. Characterization of the tunneling conductance across DNA bases

    SciTech Connect

    Zikic, Radomir; Krstic, Predrag S; Zhang, Xiaoguang; Fuentes-Cabrera, Miguel A; Wells, Jack C; Zhao, Xiongce

    2006-01-01

    Characterization of the electrical properties of the DNA bases, Adenine, Cytosine, Guanine and Thymine, besides building the basic knowledge on these fundamental constituents of a DNA, is a crucial step in developing a DNA sequencing technology. We present a first-principles study of the current-voltage characteristics of nucleotide-like molecules of the DNA bases, placed in a 1.5 nm gap formed between gold nanoelectrodes. The quantum transport calculations in the tunneling regime are shown to vary strongly with the electrode-molecule geometry and the choice of the DFT exchangecorrelation functionals. Analysis of the results in the zero-bias limit indicates that distinguishable current-voltage characteristics of different DNA bases are dominated by the geometrical conformations of the bases and nanoelectrodes.

  14. PFNA-based measurements for non-intrusive waste characterization

    SciTech Connect

    Pentaleri, E.

    1994-12-31

    Pulsed Fast Neutron Analysis (PFNA) is a non-intrusive technique for inspecting bulk samples whose size may range from that of a suitcase to that of a commercial-cargo truck trailer. In an earlier paper, the authors discussed techniques for performing PFNA-based TRU assays on waste drums, and described why such measurements would yield improved accuracy, sensitivity, and throughput over existing instruments. Here they describe a set of non-intrusive measurements useful for further improving the accuracy of TRU assay results, certifying compliance with waste acceptance criteria, or enhancing the control of waste-treatment processes. In principle, these measurements, based mainly upon the analysis of inelastic-neutron-scattering and neutron-capture gamma rays, can be performed concurrently with TRU-assay measurements. Based on the measurements described, a single PFNA-based waste inspection system would allow substantially complete non-intrusive characterization of waste containers to be performed.

  15. Breast tumor characterization based on ultrawideband microwave backscatter.

    PubMed

    Davis, Shakti K; Van Veen, Barry D; Hagness, Susan C; Kelcz, Frederick

    2008-01-01

    Characterization of architectural tissue features such as the shape, margin, and size of a suspicious lesion is commonly performed in conjunction with medical imaging to provide clues about the nature of an abnormality. In this paper, we numerically investigate the feasibility of using multichannel microwave backscatter in the 1-11 GHz band to classify the salient features of a dielectric target. We consider targets with three shape characteristics: smooth, microlobulated, and spiculated; and four size categories ranging from 0.5 to 2 cm in diameter. The numerical target constructs are based on Gaussian random spheres allowing for moderate shape irregularities. We perform shape and size classification for a range of signal-to-noise ratios (SNRs) to demonstrate the potential for tumor characterization based on ultrawideband (UWB) microwave backscatter. We approach classification with two basis selection methods from the literature: local discriminant bases and principal component analysis. Using these methods, we construct linear classifiers where a subset of the bases expansion vectors are the input features and we evaluate the average rate of correct classification as a performance measure. We demonstrate that for 10 dB SNR, the target size is very reliably classified with over 97% accuracy averaged over 360 targets; target shape is classified with over 70% accuracy. The relationship between the SNR of the test data and classifier performance is also explored. The results of this study are very encouraging and suggest that both shape and size characteristics of a dielectric target can be classified directly from its UWB backscatter. Hence, characterization can easily be performed in conjunction with UWB radar-based breast cancer detection without requiring any special hardware or additional data collection. PMID:18232367

  16. Shell-NASA Vibration-Based Damage Characterization

    NASA Technical Reports Server (NTRS)

    Rollins, John M.

    2014-01-01

    This article describes collaborative research between Shell International Exploration and Production (IE&P) scientists and ISAG personnel to investigate the feasibility of ultrasonic-based characterization of spacecraft tile damage for in-space inspection applications. The approach was proposed by Shell personnel in a Shell-NASA "speed-matching" session in early 2011 after ISAG personnel described challenges inherent in the inspection of MMOD damage deep within spacecraft thermal protection system (TPS) tiles. The approach leveraged Shell's relevant sensor and analytical expertise. The research addressed the difficulties associated with producing 3D models of MMOD damage cavities under the surface of a TPS tile, given that simple image-based sensing is constrained by line of sight through entry holes that have diameters considerably smaller than the underlying damage cavities. Damage cavity characterization is needed as part of a vehicle inspection and risk reduction capability for long-duration, human-flown space missions. It was hoped that cavity characterization could be accomplished through the use of ultrasonic techniques that allow for signal penetration through solid material.

  17. BASE: Bayesian Astrometric and Spectroscopic Exoplanet Detection and Characterization Tool

    NASA Astrophysics Data System (ADS)

    Schulze-Hartung, Tim

    2012-08-01

    BASE is a novel program for the combined or separate Bayesian analysis of astrometric and radial-velocity measurements of potential exoplanet hosts and binary stars. The tool fulfills two major tasks of exoplanet science, namely the detection of exoplanets and the characterization of their orbits. BASE was developed to provide the possibility of an integrated Bayesian analysis of stellar astrometric and Doppler-spectroscopic measurements with respect to their binary or planetary companions’ signals, correctly treating the astrometric measurement uncertainties and allowing to explore the whole parameter space without the need for informative prior constraints. The tool automatically diagnoses convergence of its Markov chain Monte Carlo (MCMC[2]) sampler to the posterior and regularly outputs status information. For orbit characterization, BASE delivers important results such as the probability densities and correlations of model parameters and derived quantities. BASE is a highly configurable command-line tool developed in Fortran 2008 and compiled with GFortran. Options can be used to control the program’s behaviour and supply information such as the stellar mass or prior information. Any option can be supplied in a configuration file and/or on the command line.

  18. Combustion characterization of beneficiated coal-based fuels

    SciTech Connect

    Chow, O.K.; Nsakala, N.Y.

    1990-11-01

    The Pittsburgh Energy Technology Center of the US Department of Energy has contracted with Combustion Engineering, Inc. (CE) to perform a three-year project on Combustion Characterization of Beneficiated Coal-Based Fuels.'' The beneficiated coals are produced by other contractors under the DOE Coal Preparation Program. Several contractor-developed advanced coal cleaning processes are being run at the cleaning facility in Homer City, Pennsylvania, to produce 20-ton batches of fuels for shipment to CE's laboratory in Windsor, Connecticut. CE then processes the products into either a coal-water fuel (CVVT) or a dry microfine pulverized coal (DMPC) form for combustion testing. The objectives of this project include: (1) the development of an engineering data base which will provide detailed information on the properties of BCFs influencing combustion, ash deposition, ash erosion, particulate collection, and emissions; and (2) the application of this technical data base to predict the performance and economic impacts of firing the BCFs in various commercial boiler designs. The technical approach used to develop the technical data includes: bench-scale fuel property, combustion, and ash deposition tests; pilot-scale combustion and ash effects tests; and full-scale combustion tests. Subcontractors to CE to perform parts of the test work are the Massachusetts Institute of Technology (MIT), Physical Science, Inc. Technology Company (PSIT) and the University of North Dakota Energy and Environmental Research Center (UNDEERC). Twenty fuels will be characterized during the three-year base program: three feed coals, fifteen BCFS, and two conventionally cleaned coals for full-scale tests. Approximately, nine BCFs will be in dry microfine coal (DMPC) form, and six BCFs will be in coal-water fuel (CWF) form. Additional BCFs would be characterized during optional project supplements.

  19. Combustion characterization of beneficiated coal-based fuels

    SciTech Connect

    Chow, O.K.; Nsakala, N.Y.

    1990-08-01

    The objectives of this project include: (1) the development of an engineering data base which will provide detailed information on the properties of BCFs influencing combustion, ash deposition, ash erosion, particulate collection, and emissions; and (2) the application of this technical data base to predict the performance and economic impacts of firing the BCFs in various commercial boiler designs. The technical approach used to develop the technical data includes: bench-scale fuel property, conbustion, and ash deposition tests; pilot-scale combustion and ash effects tests; and full-scale combustion tests. Subcontractors to CE to perform parts of the test work are the Massachusetts Institute of Technology (MIT), Physical Sciences, Inc. Technology Company (PSIT) and the University of North Dakota Energy and Environmental Research Center (UNDEERC). Twenty fuels will be characterized during the three-year base program: three feed coals, fifteen BCFs, and two conventionally cleaned coals for the full-scale tests. Approximately nine BCFs will be in dry ultra-fine coal (DUC) form, and six BCFs will be in coal-water fuel (CWF) form. Additional BCFs would be characterized during optional project supplements.

  20. Characterizing Exoplanets with 2-meter Class Space-based Coronagraphs

    NASA Astrophysics Data System (ADS)

    Robinson, T. D.; Marley, M. S.; Stapelfeldt, K. R.

    2015-12-01

    Several concepts now exist for small, space-based missions to directly characterize exoplanets in reflected light. In this presentation, we explore how instrumental and astrophysical parameters will affect the ability of such missions to obtain spectral and photometric observations that are useful for characterizing their planetary targets. We discuss the development of an instrument noise model suitable for studying the spectral characterization potential of a coronagraph-equipped, space-based telescope. To be consistent with near-future missions and technologies, we assume a baseline set of telescope and instrument parameters that include a 2 meter diameter primary aperture, an operational wavelength range of 0.4-1.0 μm, and an instrument spectral resolution of λ/Δλ=70. We present applications of our baseline noise simulator to a variety of spectral models of different planet types, emphasizing Earth-like planets. With our exoplanet spectral models, we explore wavelength-dependent planet-star flux ratios for main sequence stars of various effective temperatures, and discuss how coronagraph inner and outer working angle constraints will influence the potential to study different types of planets. For planets most favorable to spectroscopic characterization—including nearby Earth twins and super-Earths—we study the integration times required to achieve moderate signal-to-noise ratio spectra. We also explore the sensitivity of the integration times required to detect the base of key absorption bands (for water vapor and molecular oxygen) to coronagraph raw contrast performance, exozodiacal light levels, and the distance to the planetary system. We will also discuss prospects for detecting ocean glint, a habitability signature, from nearby Earth-like planets, as well as the extension of our models to a more distant future Large UV-Optical-InfraRed (LUVOIR) mission.

  1. Cure characterization and process modeling of soy-based composites

    NASA Astrophysics Data System (ADS)

    Liang, Guanghui

    This work deals with cure characteristics of soy-based resin system, fabrication of pultruded soy-based composites, and analysis of flexible polymeric foams. In the first part of this work, the cure kinetics and rheology of the soy-based resin system were studied. The cure kinetics models of the different resin formulations were developed. A neural network based model was developed to provide an efficient approach for rheology characterization. The analytical expressions of cure kinetics and rheology developed for soy-based epoxy resin system can be readily applied into numerical modeling of composite manufacturing processes. In the second part of this work, the analytical cure kinetics model developed for the soy-based epoxy resin system was applied in pultrusion process modeling. A finite element model was established and implemented in the commercial ABAQUS code to predict the temperature and the degree of cure of the pultruded soy-based composites. An on-line cure monitoring system was developed to measure the temperature profile in the pultrusion die. The numerical results show good agreement with the experimental findings. The soy-based resin system is a viable alternative to petroleum based epoxy resins for the pultrusion process. In the third part of this work, a novel constitutive model for elastomeric foam material based on neural network is presented. The neural network approach provides an efficient constitutive model and can be readily implemented into commercial finite element packages. It has the potential to be used in various applications related to analysis of polymeric foam materials.

  2. Characterization of etched facets for GaN-based lasers

    NASA Astrophysics Data System (ADS)

    Scherer, M.; Schwegler, V.; Seyboth, M.; Eberhard, F.; Kirchner, C.; Kamp, M.; Ulu, G.; Ünlü, M. S.; Gruhler, R.; Hollricher, O.

    2001-09-01

    Dry-etching of laser facets is commonly used for (InAl)GaN/sapphire-based structures since the epitaxial planes of the nitride layers are rotated with respect to the substrate planes making cleaving impractical. To achieve steep and smooth facets by chemically assisted ion beam etching, a 3-layer resist system is developed for patterning. Characterization by scanning electron microscopy and atomic force microscopy shows facets with root-mean-square roughnesses of 7 nm and inclination angles of 2-4°. Optically pumped lasers yield low threshold excitation densities for fully doped separate confinement heterostructure lasers.

  3. Characterizing cerebrovascular dynamics with the wavelet-based multifractal formalism

    NASA Astrophysics Data System (ADS)

    Pavlov, A. N.; Abdurashitov, A. S.; Sindeeva, O. A.; Sindeev, S. S.; Pavlova, O. N.; Shihalov, G. M.; Semyachkina-Glushkovskaya, O. V.

    2016-01-01

    Using the wavelet-transform modulus maxima (WTMM) approach we study the dynamics of cerebral blood flow (CBF) in rats aiming to reveal responses of macro- and microcerebral circulations to changes in the peripheral blood pressure. We show that the wavelet-based multifractal formalism allows quantifying essentially different reactions in the CBF-dynamics at the level of large and small cerebral vessels. We conclude that unlike the macrocirculation that is nearly insensitive to increased peripheral blood pressure, the microcirculation is characterized by essential changes of the CBF-complexity.

  4. Synthesis and characterization of novel cardanol based benzoxazines.

    PubMed

    Minigher, Andrea; Benedetti, Elena; De Giacomo, Ornela; Campaner, Pietro; Aroulmoji, Vincent

    2009-04-01

    Benzoxazines are a class of phenolic compounds extensively studied in polymer science because of their properties as fiber reinforcements, fire-retardants and curing agents. In this article is described a solvent-less process, based on a Mannich reaction involving a primary amine and an aldehyde, for the preparation of new benzoxazines deriving from cardanol (a well known phenol obtained as a renewable organic resource and harmful by-product of the cashew industry). Particular attention is given to the synthesis and chemical characterization (both by 1H NMR spectroscopy and HPLC), while the thermal polymerization process has been monitored by differential scanning calorimetry. PMID:19475998

  5. Characterizing unextendible product bases in qutrit-ququad system

    PubMed Central

    Yang, Ying-Hui; Gao, Fei; Xu, Guang-Bao; Zuo, Hui-Juan; Zhang, Zhi-Chao; Wen, Qiao-Yan

    2015-01-01

    Unextendible product bases (UPBs) play an important role in quantum information theory. However, very little is known about UPBs in Hilbert space of local dimension more than three. In this paper, we study the UPBs in qutrit-ququad system and find that there only exist six, seven and eight-state UPBs. We completely characterize the six-state and seven-state UPBs. For eight-state UPBs, seven classes of UPBs are found. As auxiliary results, we study the distinguishability of qutrit-ququad UPBs by separable measurements, and find that there exists a UPB that cannot be distinguished. PMID:26169249

  6. Hydration and energy dissipation measurements of biomolecules on a piezoelectric quartz oscillator by admittance analyses.

    PubMed

    Ozeki, Tomomitsu; Morita, Mizuki; Yoshimine, Hiroshi; Furusawa, Hiroyuki; Okahata, Yoshio

    2007-01-01

    , DNAs, and pullulans were relatively deviant toward the large hydration and energy dissipation from the theoretical line as perfect elastic materials, meaning that the large energy dissipation occurs because of viscoelastic properties of denatured proteins, linear DNAs, and pullulans in the water phase, in addition to energy dissipation due to the hydration of molecules. These two parameters could characterize various biomolecules with structural properties in aqueous solutions. PMID:17194124

  7. Transuranic waste form characterization and data base. Executive summary

    SciTech Connect

    Not Available

    1980-09-30

    The Transuranic Waste Form Characterization and Data Base (Volume 1) provides a wide range of information from which a comprehensive data base can be established and from which standards and criteria can be developed for the present NRC waste management program. Supplementary information on each of the areas discussed in Volume 1 is presented in Appendices A through K (Volumes 2 and 3). The structure of the study (Volume 1) is outlined and appendices of Volumes 2 and 3 correlate with each main section of the report. The Executive Summary reviews the sources, quantities, characteristics and treatment of transuranic wastes in the United States. Due to the variety of potential treatment processes for transuranic wastes, the end products for long-term storage may have corresponding variations in quantities and characteristics.

  8. Dynamic mechanical characterization and modelling of polypropylene based organoclay nanocomposite

    NASA Astrophysics Data System (ADS)

    Wang, Kui; Matadi Boumbimba, Rodrigue; Bahlouli, Nadia; Ahzi, Said; Muller, René

    2015-09-01

    In order to investigate the dynamic behaviour of polypropylene based organoclay nanocomposite, the polypropylene matrix and a master batch of polypropylene modified anhydrid maleic were mixed by means of melt mixing technique. The experimental characterization was performed by using split Hopkinson pressure bars (SHPB), at different strain rates and temperatures. A significant increase of the yield stress of nanocomposite was shown with the present of organoclay, comparing to neat PP. A three-phase approach based on the micromechanical formulation of the cooperative model is proposed to model the yield behaviour of the polymer nanocomposite. Our proposed approach accounts for strain rate and temperature effects as well as the organoclay exfoliation effect. The predictions of models for the nanocomposite yield behaviour showed a good agreement with experimental data.

  9. Developing Hydrogeological Site Characterization Strategies based on Human Health Risk

    NASA Astrophysics Data System (ADS)

    de Barros, F.; Rubin, Y.; Maxwell, R. M.

    2013-12-01

    In order to provide better sustainable groundwater quality management and minimize the impact of contamination in humans, improved understanding and quantification of the interaction between hydrogeological models, geological site information and human health are needed. Considering the joint influence of these components in the overall human health risk assessment and the corresponding sources of uncertainty aid decision makers to better allocate resources in data acquisition campaigns. This is important to (1) achieve remediation goals in a cost-effective manner, (2) protect human health and (3) keep water supplies clean in order to keep with quality standards. Such task is challenging since a full characterization of the subsurface is unfeasible due to financial and technological constraints. In addition, human exposure and physiological response to contamination are subject to uncertainty and variability. Normally, sampling strategies are developed with the goal of reducing uncertainty, but less often they are developed in the context of their impacts on the overall system uncertainty. Therefore, quantifying the impact from each of these components (hydrogeological, behavioral and physiological) in final human health risk prediction can provide guidance for decision makers to best allocate resources towards minimal prediction uncertainty. In this presentation, a multi-component human health risk-based framework is presented which allows decision makers to set priorities through an information entropy-based visualization tool. Results highlight the role of characteristic length-scales characterizing flow and transport in determining data needs within an integrated hydrogeological-health framework. Conditions where uncertainty reduction in human health risk predictions may benefit from better understanding of the health component, as opposed to a more detailed hydrogeological characterization, are also discussed. Finally, results illustrate how different dose

  10. Network fingerprint: a knowledge-based characterization of biomedical networks

    PubMed Central

    Cui, Xiuliang; He, Haochen; He, Fuchu; Wang, Shengqi; Li, Fei; Bo, Xiaochen

    2015-01-01

    It can be difficult for biomedical researchers to understand complex molecular networks due to their unfamiliarity with the mathematical concepts employed. To represent molecular networks with clear meanings and familiar forms for biomedical researchers, we introduce a knowledge-based computational framework to decipher biomedical networks by making systematic comparisons to well-studied “basic networks”. A biomedical network is characterized as a spectrum-like vector called “network fingerprint”, which contains similarities to basic networks. This knowledge-based multidimensional characterization provides a more intuitive way to decipher molecular networks, especially for large-scale network comparisons and clustering analyses. As an example, we extracted network fingerprints of 44 disease networks in the Kyoto Encyclopedia of Genes and Genomes (KEGG) database. The comparisons among the network fingerprints of disease networks revealed informative disease-disease and disease-signaling pathway associations, illustrating that the network fingerprinting framework will lead to new approaches for better understanding of biomedical networks. PMID:26307246

  11. Preparation and characterization of silicon oil based ferrofluid

    NASA Astrophysics Data System (ADS)

    Chen, H. J.; Wang, Y. M.; Qu, J. M.; Hong, R. Y.; Li, H. Z.

    2011-10-01

    Stable silicon oil based ferrofluid was prepared in the present investigation. Silicon oil surfactant ethoxy terminated polydimethylsiloxane was used to modify the Fe 3O 4 nanoparticles. The Fe 3O 4 nanoparticles were firstly coated with a SiO 2 layer by the hydrolysis of tetraethoxysilane. Then using the active hydroxyl groups on the surface of the SiO 2, silicon oil surfactant was covalently grafted onto the Fe 3O 4 nanoparticles surface. The ethoxy terminated polydimethylsiloxane has similar molecular chain structure and good compatibility with that of the carrier liquid, thus ensuring stable dispersion of modified Fe 3O 4 in the carrier silicon oil. The interaction between Fe 3O 4 and the modifier was characterized by IR and XPS. The crystal structure and the magnetic properties of the Fe 3O 4 nanoparticles were determined by XRD and VSM, respectively. The size and morphology of the particles were observed using TEM. The properties of the silicon oil based ferrofluid were characterized by Gouy magnetic balance. The results indicated that the ferrofluid had high magnetism and good stability. The rheological properties and thermostability of the ferrofluid were also investigated.

  12. Synthesis and Characterization of Gelatin-Based Magnetic Hydrogels

    PubMed Central

    Helminger, Maria; Wu, Baohu; Kollmann, Tina; Benke, Dominik; Schwahn, Dietmar; Pipich, Vitaliy; Faivre, Damien; Zahn, Dirk; Cölfen, Helmut

    2014-01-01

    A simple preparation of thermoreversible gelatin-based ferrogels in water provides a constant structure defined by the crosslinking degree for gelatin contents between 6 and 18 wt%. The possibility of varying magnetite nanoparticle concentration between 20 and 70 wt% is also reported. Simulation studies hint at the suitability of collagen to bind iron and hydroxide ions, suggesting that collagen acts as a nucleation seed to iron hydroxide aggregation, and thus the intergrowth of collagen and magnetite nanoparticles already at the precursor stage. The detailed structure of the individual ferrogel components is characterized by small-angle neutron scattering (SANS) using contrast matching. The magnetite structure characterization is supplemented by small-angle X-ray scattering and microscopy only visualizing magnetite. SANS shows an unchanged gelatin structure of average mesh size larger than the nanoparticles with respect to gel concentration while the magnetite nanoparticles size of around 10 nm seems to be limited by the gel mesh size. Swelling measurements underline that magnetite acts as additional crosslinker and therefore varying the magnetic and mechanical properties of the ferrogels. Overall, the simple and variable synthesis protocol, the cheap and easy accessibility of the components as well as the biocompatibility of the gelatin-based materials suggest them for a number of applications including actuators. PMID:25844086

  13. Characterization of glass-infiltrated alumina-based ceramics

    PubMed Central

    Bona, Alvaro Della; Mecholsky, John J; Barrett, Allyson A; Griggs, Jason A

    2010-01-01

    Objective characterize the microstructure, composition, and important properties of glass-infiltrated alumina-based ceramics similar to the In-Ceram system. Methods Materials used were: IA- In-Ceram Alumina (Vita); IAE- IA electrophoretically deposited (Vita); AEM- IA using a vacuum driven method (Vita); VC- Vitro-Ceram (Angelus); TC- Turkom-Cera (Turkom-Ceramic); CC- Ceramcap (Foto-Ceram); and AG- Alglass (EDG). Ceramic specimens were fabricated following manufacturers’ instructions and ISO6872 standard and polished successively through 1μm alumina abrasive. Semi-quantitative and qualitative analyses were performed using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and stereology (Vv). The elastic modulus (E) and Poisson’s ratio (ν) were determined using time-of-flight data measured in an ultrasonic pulser/receiver and the density (ρ) was determined using a helium pycnometer. Vicker’s indentation was used to calculate hardness (H). Bar specimens (25×4×1.2mm3) were loaded in three-point bending to fracture using a universal testing machine with cross-head speed of 1mm/min. Flexural strength (σ3P) was calculated and statistically analyzed using ANOVA, Tukey (α=0.05) and Weibull (m= modulus, σ0= characteristic strength). Results SEM and EDS analyses revealed similar microstructure for all ceramics, except for a lead-based matrix in CC and a zirconia phase in VC. TC, AG and CC showed significantly lower mean σ3P values than the other ceramics (p 0.05). AEM showed the greatest m (16). Conclusion Despite few differences in microstructure and composition, the IA, IAE, AEM and VC ceramics have similar properties. Significance The glass-infiltrated alumina-based ceramics from different manufacturers presented distinct characteristics. It is necessary to characterize new commercially available materials to understand their properties. PMID:18692231

  14. Processing and characterization of extruded zein-based biodegradable films

    NASA Astrophysics Data System (ADS)

    Wang, Ying

    The objectives of this study were to prepare biodegradable zein films by extrusion processing and to evaluate relevant physical properties of resulting films with respect to their potential as packaging materials. The manufacture of protein-based packaging films by extrusion has remained a challenge. In this study, a zein resin was prepared by combining zein and oleic acid. This resin was formed into films by blown extrusion at the bench-top scale. Resin moisture content and extruder barrel temperature profile were identified as major parameters controlling the process. The optimum temperature of the blowing head was determined to be 40--45°C, while optimum moisture at film collection was 14--15%. Physico-chemical properties of the extruded products were characterized. Extruded products exhibited plastic behavior and ductility. Morphology characterization by SEM showed micro voids in extruded zein sheets, caused by entrapped air bubbles or water droplets. DSC characterization showed that zein was effectively plasticized by oleic acid as evidenced by the lowered glass transition temperature of zein films. X-ray scattering was used to investigate changes in zein molecular aggregation during processing. It was observed that higher mechanical energy treatment progressively disrupted zein molecular aggregates, resulting in a more uniform distribution of individual zein molecules. With the incorporation of oleic acid as plasticizer and monoglycerides as emulsifier, zein formed structures with long-range periodicity which varied depending on the formulation and processing methods. Processing methods for film formation affected the binding of oleic acid to zein with higher mechanical energy treatment resulting in better interaction between the two components. The moisture sorption capacity of extruded zein films was reduced due to the compact morphology caused by extrusion. Plasticization with oleic acid further reduced moisture sorption of zein films. The overall

  15. [On-Orbit Multispectral Sensor Characterization Based on Spectral Tarps].

    PubMed

    Li, Xin; Zhang, Li-ming; Chen, Hong-yao; Xu, Wei-wei

    2016-03-01

    The multispectral remote sensing technology has been a primary means in the research of biomass monitoring, climate change, disaster prediction and etc. The spectral sensitivity is essential in the quantitative analysis of remote sensing data. When the sensor is running in the space, it will be influenced by cosmic radiation, severe change of temperature, chemical molecular contamination, cosmic dust and etc. As a result, the spectral sensitivity will degrade by time, which has great implication on the accuracy and consistency of the physical measurements. This paper presents a characterization method of the degradation based on man-made spectral targets. Firstly, a degradation model is established in the paper. Then, combined with equivalent reflectance of spectral targets measured and inverted from image, the degradation characterization can be achieved. The simulation and on orbit experiment results showed that, using the proposed method, the change of center wavelength and band width can be monotored. The method proposed in the paper has great significance for improving the accuracy of long time series remote sensing data product and comprehensive utilization level of multi sensor data products. PMID:27400529

  16. Micro-reactors for characterization of nanostructure-based sensors

    NASA Astrophysics Data System (ADS)

    Savu, R.; Silveira, J. V.; Flacker, A.; Vaz, A. R.; Joanni, E.; Pinto, A. C.; Gobbi, A. L.; Santos, T. E. A.; Rotondaro, A. L. P.; Moshkalev, S. A.

    2012-05-01

    Fabrication and testing of micro-reactors for the characterization of nanosensors is presented in this work. The reactors have a small volume (100 μl) and are equipped with gas input/output channels. They were machined from a single piece of kovar in order to avoid leaks in the system due to additional welding. The contact pins were electrically insulated from the body of the reactor using a borosilicate sealing glass and the reactor was hermetically sealed using a lid and an elastomeric o-ring. One of the advantages of the reactor lies in its simple assembly and ease of use with any vacuum/gas system, allowing the connection of more than one device. Moreover, the lid can be modified in order to fit a window for in situ optical characterization. In order to prove its versatility, carbon nanotube-based sensors were tested using this micro-reactor. The devices were fabricated by depositing carbon nanotubes over 1 μm thick gold electrodes patterned onto Si/SiO2 substrates. The sensors were tested using oxygen and nitrogen atmospheres, in the pressure range between 10-5 and 10-1 mbar. The small chamber volume allowed the measurement of fast sensor characteristic times, with the sensors showing good sensitivity towards gas and pressure as well as high reproducibility.

  17. Starch nanocrystals based hydrogel: Construction, characterizations and transdermal application.

    PubMed

    Bakrudeen, Haja Bava; Sudarvizhi, C; Reddy, B S R

    2016-11-01

    Bio-based nanocomposites were prepared using starch nanocrystals obtained by acid hydrolysis of native starches using different acid sources. In recent times, focuses on starch nanocrystals (SNCs) have been increasing in number of research works dedicated to the development of bio-nanocomposites by blending with different biopolymeric matrices. The work mainly deals with the preparation of starch nanocrystals using different native starches by acid hydrolysis using hydrochloric acid and trifluroacetic acid. The as-prepared starch nanocrystals are having high crystallinity and more platelet morphologies, and used as a drug carrying filler material in the hydrogel formulations with the care of different polymer matrices. The condensed work also concentrates on the dispersion of antiviral drug in the hydrogels, which are applied onto biocompatible bio-membrane to be formulating a complete transdermal patch. The acid hydrolysed starch nanocrystals were thoroughly characterized using TEM, SEM, particle size analysis and zeta potential. Their thermal stability and the crystalline properties were also characterized using TG-DSC and XRD respectively. The physiochemical interaction and compatibility between the drug and the SNCs filler in the polymeric hydrogels were evaluated using FT-IR analysis. The formulated hydrogels were subjected to evaluation of in vitro permeation studies using Franz diffusion studies. The in vitro study was indicated substantial guarantee for the fabrication of drug dispersed in polymeric hydrogels using SNCs as filler matrices for a successful transdermal drug delivery. PMID:27524091

  18. Quantitative proteome-based guidelines for intrinsic disorder characterization.

    PubMed

    Vincent, Michael; Whidden, Mark; Schnell, Santiago

    2016-06-01

    Intrinsically disordered proteins fail to adopt a stable three-dimensional structure under physiological conditions. It is now understood that many disordered proteins are not dysfunctional, but instead engage in numerous cellular processes, including signaling and regulation. Disorder characterization from amino acid sequence relies on computational disorder prediction algorithms. While numerous large-scale investigations of disorder have been performed using these algorithms, and have offered valuable insight regarding the prevalence of protein disorder in many organisms, critical proteome-based descriptive statistical guidelines that would enable the objective assessment of intrinsic disorder in a protein of interest remain to be established. Here we present a quantitative characterization of numerous disorder features using a rigorous non-parametric statistical approach, providing expected values and percentile cutoffs for each feature in ten eukaryotic proteomes. Our estimates utilize multiple ab initio disorder prediction algorithms grounded on physicochemical principles. Furthermore, we present novel threshold values, specific to both the prediction algorithms and the proteomes, defining the longest primary sequence length in which the significance of a continuous disordered region can be evaluated on the basis of length alone. The guidelines presented here are intended to improve the interpretation of disorder content and continuous disorder predictions from the proteomic point of view. PMID:27085142

  19. [Colorimetric characterization of LCD based on wavelength partition spectral model].

    PubMed

    Liu, Hao-Xue; Cui, Gui-Hua; Huang, Min; Wu, Bing; Xu, Yan-Fang; Luo, Ming

    2013-10-01

    To establish a colorimetrical characterization model of LCDs, an experiment with EIZO CG19, IBM 19, DELL 19 and HP 19 LCDs was designed and carried out to test the interaction between RGB channels, and then to test the spectral additive property of LCDs. The RGB digital values of single channel and two channels were given and the corresponding tristimulus values were measured, then a chart was plotted and calculations were made to test the independency of RGB channels. The results showed that the interaction between channels was reasonably weak and spectral additivity property was held well. We also found that the relations between radiations and digital values at different wavelengths varied, that is, they were the functions of wavelength. A new calculation method based on piecewise spectral model, in which the relation between radiations and digital values was fitted by a cubic polynomial in each piece of wavelength with measured spectral radiation curves, was proposed and tested. The spectral radiation curves of RGB primaries with any digital values can be found out with only a few measurements and fitted cubic polynomial in this way and then any displayed color can be turned out by the spectral additivity property of primaries at given digital values. The algorithm of this method was discussed in detail in this paper. The computations showed that the proposed method was simple and the number of measurements needed was reduced greatly while keeping a very high computation precision. This method can be used as a colorimetrical characterization model. PMID:24409730

  20. Characterizing GEO Titan Transtage Fragmentations using Ground-based Measurements

    NASA Technical Reports Server (NTRS)

    Cowardin, H.; Anz-Meador, P.

    2016-01-01

    In a continued effort to better characterize the Geosynchronous Orbit (GEO) environment, NASA's Orbital Debris Program Office (ODPO) utilizes various ground-based optical assets to acquire photometric and spectral data of known debris associated with fragmentations in or near GEO. The Titan IIIC Transtage upper stage is known to have fragmented four times. Two of the four fragmentations were in GEO while a third Transtage fragmented in GEO transfer orbit. The forth fragmentation occurred in Low Earth Orbit. In order to better assess what may be causing these fragmentations, the NASA ODPO recently acquired a Titan Transtage test and display article that was previously in the custody of the 309th Aerospace Maintenance and Regeneration Group (AMARG) in Tucson, Arizona. After initial inspections at AMARG demonstrated that the test article was of sufficient fidelity to be of interest, the test article was brought to JSC to continue material analysis and historical documentation of the Titan Transtage. The Transtage will be a subject of forensic analysis using spectral measurements to compare with telescopic data; as well, a scale model will be created to use in the Optical Measurement Center for photometric analysis of an intact Transtage, including a BRDF. The following presentation will provide a review of the Titan Transtage, the current analysis that has been done to date, and the future work to be completed in support of characterizing the GEO and near GEO orbital debris environment.

  1. Micro-reactors for characterization of nanostructure-based sensors.

    PubMed

    Savu, R; Silveira, J V; Flacker, A; Vaz, A R; Joanni, E; Pinto, A C; Gobbi, A L; Santos, T E A; Rotondaro, A L P; Moshkalev, S A

    2012-05-01

    Fabrication and testing of micro-reactors for the characterization of nanosensors is presented in this work. The reactors have a small volume (100 μl) and are equipped with gas input/output channels. They were machined from a single piece of kovar in order to avoid leaks in the system due to additional welding. The contact pins were electrically insulated from the body of the reactor using a borosilicate sealing glass and the reactor was hermetically sealed using a lid and an elastomeric o-ring. One of the advantages of the reactor lies in its simple assembly and ease of use with any vacuum/gas system, allowing the connection of more than one device. Moreover, the lid can be modified in order to fit a window for in situ optical characterization. In order to prove its versatility, carbon nanotube-based sensors were tested using this micro-reactor. The devices were fabricated by depositing carbon nanotubes over 1 μm thick gold electrodes patterned onto Si/SiO(2) substrates. The sensors were tested using oxygen and nitrogen atmospheres, in the pressure range between 10(-5) and 10(-1) mbar. The small chamber volume allowed the measurement of fast sensor characteristic times, with the sensors showing good sensitivity towards gas and pressure as well as high reproducibility. PMID:22667654

  2. An impedance-based integrated biosensor for suspended DNA characterization

    PubMed Central

    Ma, Hanbin; Wallbank, Richard W. R.; Chaji, Reza; Li, Jiahao; Suzuki, Yuji; Jiggins, Chris; Nathan, Arokia

    2013-01-01

    Herein, we describe a novel integrated biosensor for performing dielectric spectroscopy to analyze biological samples. We analyzed biomolecule samples with different concentrations and demonstrated that the solution's impedance is highly correlated with the concentration, indicating that it may be possible to use this sensor as a concentration sensor. In contrast with standard spectrophotometers, this sensor offers a low-cost and purely electrical solution for the quantitative analysis of biomolecule solutions. In addition to determining concentrations, we found that the sample solution impedance is highly correlated with the length of the DNA fragments, indicating that the sizes of PCR products could be validated with an integrated chip-based, sample-friendly system within a few minutes. The system could be the basis of a rapid, low-cost platform for DNA characterization with broad applications in cancer and genetic disease research. PMID:24060937

  3. Synthesis and Characterization of Tetramethylethylenediamine-Based Hypergolic Ionic Liquids

    NASA Astrophysics Data System (ADS)

    Fei, Teng; Cai, Huiwu; Zhang, Yanqiang; Liu, Long; Zhang, Suojiang

    2016-04-01

    Four energetic salts (including two ionic liquids) based on 2-(dimethylamino)-N,N,N-trimethylethanaminium and N,N‧-dialkyl-N,N,N‧,N‧-tetramethylethane-1,2-diaminium was prepared and characterized by 1H- and 13C-NMR, infrared and Raman spectroscopies, and elemental analysis. Their physicochemical properties such as melting and decomposition temperatures, density, viscosity, heat of formation, detonation performance, and specific impulse were measured or calculated. With thermal stability up to 200°C, the resulting ionic liquids show densities from 1.02 to 1.19 g cm-3 and heats of formation from 85.1 to 154.4 kJ mol-1. Moreover, 2-(dimethylamino)-N,N,N-trimethylethanaminium dicyanamide is hypergolic with the oxidizer (100% HNO3) and exhibits potential as a green fuel for bipropellants.

  4. Vortex-based spatiotemporal characterization of nonlinear flows

    NASA Astrophysics Data System (ADS)

    Byrne, Gregory A.

    Although the ubiquity of vortices in nature has been recognized by artists for over seven centuries, it was the work of artist and scientist Leonardo da Vinci that provided the monumental transition from an aesthetic form to a scientific tool. DaVinci used vortices to describe the motions he observed in air currents, flowing water and blood flow in the human heart. Five centuries later, the Navier-Stokes equations allow us to recreate the swirling motions of fluid observed in nature. Computational fluid dynamic (CFD) simulations have provided a lens through which to study the role of vortices in a wide variety of modern day applications. The research summarized below represents an effort to look through this lens and bring into focus the practical use of vortices in describing nonlinear flows. Vortex-based spatiotemporal characterizations are obtained using two specific mathematical tools: vortex core lines (VCL) and proper orthogonal decomposition (POD). By applying these tools, we find that vortices continue to provide new insights in the realm of biofluids, urban flows and the phase space of dynamical systems. The insights we have gained are described in this thesis. Our primary focus is on biofluids. Specifically, we seek to gain new insights into the connection between vortices and vascular diseases in order to provide more effective methods for clinical diagnosis and treatment. We highlight several applications in which VCL and POD are used to characterize the flow conditions in a heart pump, identify stenosis in carotid arteries and validate numerical models against PIV-based experimental data. Next, we quantify the spatial complexity and temporal stability of hemodynamics generated by a database of 210 patient-specific aneurysm geometries. Visual classifications of the hemodynamics are compared to the automated, quantitative classifications. The quantities characterizing the hemodynamics are then compared to clinical data to determine conditions that are

  5. Optimization algorithm based characterization scheme for tunable semiconductor lasers.

    PubMed

    Chen, Quanan; Liu, Gonghai; Lu, Qiaoyin; Guo, Weihua

    2016-09-01

    In this paper, an optimization algorithm based characterization scheme for tunable semiconductor lasers is proposed and demonstrated. In the process of optimization, the ratio between the power of the desired frequency and the power except of the desired frequency is used as the figure of merit, which approximately represents the side-mode suppression ratio. In practice, we use tunable optical band-pass and band-stop filters to obtain the power of the desired frequency and the power except of the desired frequency separately. With the assistance of optimization algorithms, such as the particle swarm optimization (PSO) algorithm, we can get stable operation conditions for tunable lasers at designated frequencies directly and efficiently. PMID:27607701

  6. Physical characterization of cadmium telluride/cadmium sulfide photovoltaics: Defects, fields, and micrononuniformities

    NASA Astrophysics Data System (ADS)

    Shvydka, Diana

    Recent advances in large area thin-film photovoltaic manufacturing have raised a number of problems related to the physical parameters and processes behind the device efficiency and stability. The characteristics of interest include the defect spectra and related optical absorption, the built-in electric field distribution, the degree of lateral uniformity of the device, and the device stability. Established in this thesis is a set of techniques appropriate for the physical characterization of the above features in CdTe/CdS solar cells, addressing the issues of device spectra vs. energy (as revealed in the optical absorption, photoluminescence (PL), and admittance spectroscopy); the electric field distribution analyzed by means of bias dependent PL, and, indirectly, by capacitance measurements; device lateral resistivity and uniformity, through the phenomenon of nonlocal optical response and PL mapping; local parameter fluctuations as appear in virtually all of the above cases. The most important physical conclusions made are: energy spectra of polycrystalline CdTe based photovoltaics combine the features of crystalline materials, such as identifiable point defects, and amorphous materials, which exhibit continuous spectra of localized states; the concept of a single-defect (elemental) capacitance is for the first time defined and applied to estimate the density of states in polycrystalline p-n junctions; a phenomenon of bias-dependent PL in CdTe based photovoltaics is for the first time observed and modeled; a new phenomenon of nonlocal photovoltaic response is observed and interpreted. The results suggest several practical applications, such as: absorption and PL measurements as a diagnostic tool for monitoring the CdCl2, quality of treatments; admittance spectroscopy techniques to diagnose the material quality and degradation through its defect spectra and concentration; bias-dependent PL as a sensitive nondestructive accelerated life testing tool; nonlocal PV

  7. Metallurgical characterization of experimental Ag-based soldering alloys

    PubMed Central

    Ntasi, Argyro; Al Jabbari, Youssef S.; Silikas, Nick; Al Taweel, Sara M.; Zinelis, Spiros

    2014-01-01

    Aim To characterize microstructure, hardness and thermal properties of experimental Ag-based soldering alloys for dental applications. Materials and methods Ag12Ga (AgGa) and Ag10Ga5Sn (AgGaSn) were fabricated by induction melting. Six samples were prepared for each alloy and microstructure, hardness and their melting range were determined by, scanning electron microscopy, energy dispersive X-ray (EDX) microanalysis, X-ray diffraction (XRD), Vickers hardness testing and differential scanning calorimetry (DSC). Results Both alloys demonstrated a gross dendritic microstructure while according to XRD results both materials consisted predominately of a Ag-rich face centered cubic phase The hardness of AgGa (61 ± 2) was statistically lower than that of AgGaSn (84 ± 2) while the alloys tested showed similar melting range of 627–762 °C for AgGa and 631–756 °C for AgGaSn. Conclusion The experimental alloys tested demonstrated similar microstructures and melting ranges. Ga and Sn might be used as alternative to Cu and Zn to modify the selected properties of Ag based soldering alloys. PMID:25382945

  8. Design, fabrication and characterization of LTCC-based electromagnetic microgenerators

    NASA Astrophysics Data System (ADS)

    Gierczak, M.; Markowski, P.; Dziedzic, A.

    2016-02-01

    Design, manufacturing process and properties of electromagnetic microgenerators fabricated in LTCC (Low Temperature Co-fired Ceramics) technology are presented in this paper. Electromagnetic microgenerators consist of planar coils spatially arranged on several layers of LTCC and of a multipole permanent magnet. Two different patterns of coils with 2-, 8-,10- and 12-layers and outer diameter of 50 mm were designed and fabricated. Silver-based pastes ESL 903-A or DuPont 6145 were used. In order to estimate the inductance of a single spatial coil the Greenhouse (self-inductance) and Hoer (mutual inductance) calculation methods were used. To verify the calculation results a single-layer coil was fabricated for each pattern and its inductance was measured using the precision RLC Meter. Fabricated LTCC microgenerators with embedded coils allow to generate voltage higher than ten volts and the electrical output power of approximately 600 mW at the rotor rotation speed of 12 thousands rpm. The self-made system was used for characterization of LTCC-based electromagnetic microgenerators.

  9. MEMS-based microstructures for nanomechanical characterization of thin films

    NASA Astrophysics Data System (ADS)

    Boé, A.; Safi, A.; Coulombier, M.; Fabrègue, D.; Pardoen, T.; Raskin, J.-P.

    2009-11-01

    The measurement of mechanical properties of thin films is a major issue for the design of reliable microelectronic devices, microsensors or thin coatings. New simple microstructures actuated through the release of internally stressed long beams made of high temperature, low pressure chemical vapour deposition silicon nitride have been developed to test under uniaxial tension submicron thin film material specimens. The relative displacement between a fixed and a moving cursor is used to determine the strain applied to the specimen. The stress is inferred based on the mismatch strain and Young's modulus of the silicon nitride actuator beam. By multiplying the tensile test microstructures with different lengths, the full stress-strain curve characterizing the thin material sample is generated from which the elastic stiffness, yield strength, ductility and fracture stress can be extracted. The potential of the method is demonstrated through applications on both brittle and ductile thin films. The Young's modulus of 238 GPa for a 373 nm thick silicon nitride film is extracted and size effects are observed for the yield strength of pure aluminium with a value of 220 and 550 MPa, respectively, for 373 and 205 nm thick films. An original variant of the procedure based on this new test microstructure for measuring Young's modulus is also presented.

  10. Hydrothermal synthesis and characterization of zirconia based catalysts

    NASA Astrophysics Data System (ADS)

    Caillot, T.; Salama, Z.; Chanut, N.; Cadete Santos Aires, F. J.; Bennici, S.; Auroux, A.

    2013-07-01

    In this work, three equimolar mixed oxides ZrO2/CeO2, ZrO2/TiO2, ZrO2/La2O3 and a reference ZrO2 have been synthesized by hydrothermal method. The structural and surface properties of these materials have been fully characterized by X-ray diffraction, transmission electron microscopy, surface area measurement, chemical analysis, XPS, infrared spectroscopy after adsorption of pyridine and adsorption microcalorimetry of NH3 and SO2 probe molecules. All investigated mixed oxides are amphoteric and possess redox centers on their surface. Moreover, hydrothermal synthesis leads to catalysts with higher surface area and with better acid-base properties than classical coprecipitation method. Both Lewis and Brønsted acid sites are present on the surface of the mixed oxides. Compared to the other samples, the ZrO2/TiO2 material appears to be the best candidate for further application in acid-base catalysis.

  11. Synthesis and characterization of cyclic acetal based degradable hydrogels.

    PubMed

    Kaihara, Sachiko; Matsumura, Shuichi; Fisher, John P

    2008-01-01

    While many synthetic, hydrolytically degradable hydrogels have been developed for biomedical applications, there are only a few examples whose polymer backbone does not form acidic products upon degradation. In order to address this concern, we proposed to develop a hydrogel based on a cyclic acetal unit that produces diols and propanals upon hydrolytic degradation. In particular, we proposed the fabrication of hydrogels formed by the free radical polymerization of two diacrylate monomers, 5-ethyl-5-(hydroxymethyl)-beta,beta-dimethyl-1,3-dioxane-2-ethanol diacrylate (EHD), a cyclic acetal having two acryl groups, and poly(ethylene glycol)diacrylate (PEGDA). However, the hydrophobicity of the EHD monomer inhibits hydrogel fabrication. Therefore this work develops a strategy to form hydrogels with a co-monomer system, one of which is hydrophobic, and subsequently describes the properties of the resulting hydrogel. Using benzoyl peroxide as an initiator and N,N-dimethyl-p-toluidine as an accelerator, the EHD and PEGDA monomers were reacted in an acetone/water co-solvent system. The chemical structure of the resulting EH-PEG [5-ethyl-5-(hydroxymethyl)-beta,beta-dimethyl-1,3-dioxane-2-ethanol-co-PEG] hydrogel was then characterized by FT-IR. Physicochemical properties of the EH-PEG hydrogel, including swelling degree, sol fraction, and contact angle, were determined so as to characterize the properties of these materials and ultimately investigate their use in drug delivery and tissue engineering applications. Results showed that EH-PEG hydrogel may be formed using the co-solvent system. Further results indicated that swelling degree is dependent upon initiator concentration, monomer concentration, and molar ratios of monomers, while sol fraction significantly depended on initiator concentration and monomer concentration, only. These results demonstrate the ability to fabricate hydrogels using EHD and PEGDA system as well as to control the properties of the resulting

  12. Characterization of quartz-based package for RF MEMS

    NASA Astrophysics Data System (ADS)

    Sordo, G.; Faes, A.; Resta, G.; Iannacci, J.

    2013-05-01

    In the last decade Micro-Electro-Mechanical Systems (MEMS) technology experienced a significant development in various fields of Information and Communication Technology (ICT). In particular MEMS for Radio Frequency (RF) applications have emerged as a remarkable solution in order to fabricate components with outstanding performances. The encapsulation of such devices is a relevant aspect to be addressed in order to enable wide exploitation of RF-MEMS technology in commercial applications. A MEMS package must not only protect fragile mechanical parts but also provide the interface to the next level of the packaging hierarchy in a cost effective technology. Additionally, in RF applications the electromagnetic impact of the package has to be carefully considered. Given such a scenario, the focus of this work is the characterization of a chip capping solution for RF-MEMS devices. Such solution uses a quartz cap having an epoxy-based dry film sealing ring. Relevant issues affecting RF-MEMS devices once packaged, e.g. the mechanical strain induced by the cap and the hermeticity of the sealing ring, are worth investigating. This work focuses on the study of induced strain, as a function of different bonding parameters. Dimensional features of the sealing ring (i.e. the width), and process parameters, like temperature and pressure, have been considered. The package characterization is performed by using basic test vehicles, such as strain gauges, designed to be integrated inside the internal cavity of the package itself. Polysilicon piezoresistors are used as strain gauges, whereas aluminum resistors are used as thermometers to assess the impact of temperature changes on strain measurements. Experimental data are reported including calibration of the sensors as well as environmental measurements with and without cap. In addition measurements of the shear stress of the proposed packaging solution are also reported.

  13. Mueller based scatterometry and optical characterization of semiconductor materials

    NASA Astrophysics Data System (ADS)

    Muthinti, Gangadhara Raja

    Scatterometry is one of the most useful metrology methods for the characterization and control of critical dimensions (CD) and the detailed topography of periodic structures found in microelectronics fabrication processes. Spectroscopic ellipsometry (SE) and normal incidence reflectometry (NI) based scatterometry are the most widely used optical methodologies for metrology of these structures. Evolution of better optical hardware and faster computing capabilities led to the development of Mueller Matrix (MM) based Scatterometry (MMS). Dimensional metrology using full Mueller Matrix (16 element) scatterometry in the wavelength range of 245nm-1000nm was discussed in this work. Unlike SE and NI, MM data provides complete information about the optical reflection and transmission of polarized light reflected from a sample. MM is a 4x4 transformation matrix (16 elements) describing the change in the intensities of incident polarized light expressed by means of a Stokes Vector. The symmetry properties associated with MM provide an excellent means of measuring and understanding the topography of the periodic nanostructures. Topography here refers to uniformity of the periodic order of arrayed structure. The advantage of MMS over traditional SE Scatterometry is the ability of MMS to measure samples that have anisotropic optical properties and depolarize light. The present work focuses on understanding the Mueller based Scatterometry with respect to other methodologies by a systematic approach. Several laterally complex nano-scale structures with dimensions in the order of nanometers were designed and fabricated using e-beam lithography. Also Mueller based analysis was used to extract profile information and anisotropy coefficients of complex 3D FinFET, SOI fin grating structures. Later, Spectroscopic Mueller matrix (all 16 elements) and SE data were collected in planar diffraction mode for the samples using a J.A. Woollam RC2(TM) Spectroscopic Ellipsometer. Nano

  14. Synthesis and characterization of triglyceride based thermosetting polymers

    NASA Astrophysics Data System (ADS)

    Can, Erde

    2005-07-01

    Plant oils, which are found in abundance in all parts of the world and are easily replenished annually, have the potential to replace petroleum as a chemical feedstock for making polymers. Within the past few years, there has been growing interest to use triglycerides as the basic constituent of thermosetting polymers with the necessary rigidity, strength and glass transition temperatures required for engineering applications. Plant oils are not polymerizable in their natural form, however various functional groups that can polymerize can easily be attached to the triglyceride structure making them ideal cross-linking monomers for thermosetting liquid molding resins. Through this research project a number of thermosetting liquid molding resins based on soybean and castor oil, which is a specialty oil with hydroxyls on its fatty acids, have been developed. The triglyceride based monomers were prepared via the malination of the alcoholysis products of soybean and castor oil with various polyols, such as pentaerythritol, glycerol, and Bisphenol A propoxylate. The malinated glycerides were then cured in the presence of a reactive diluent, such as styrene, to form rigid glassy materials with a wide range of properties. In addition to maleate half-esters, methacrylates were also introduced to the glyceride structure via methacrylation of the soybean oil glycerolysis product with methacrylic anhydride. This product, which contains methacrylic acid as by-product, and its blends with styrene also gave rigid materials when cured. The triglyceride based monomers were characterized via conventional spectroscopic techniques. Time resolved FTIR analysis was used to determine the curing kinetics and the final conversions of polymerization of the malinated glyceride-styrene blends. Dynamic Mechanical Analysis (DMA) was used to determine the thermomechanical behavior of these polymers and other mechanical properties were determined via standard mechanical tests. The use of lignin

  15. Hydrothermal synthesis and characterization of zirconia based catalysts

    SciTech Connect

    Caillot, T. Salama, Z.; Chanut, N.; Cadete Santos Aires, F.J.; Bennici, S.; Auroux, A.

    2013-07-15

    In this work, three equimolar mixed oxides ZrO{sub 2}/CeO{sub 2}, ZrO{sub 2}/TiO{sub 2}, ZrO{sub 2}/La{sub 2}O{sub 3} and a reference ZrO{sub 2} have been synthesized by hydrothermal method. The structural and surface properties of these materials have been fully characterized by X-ray diffraction, transmission electron microscopy, surface area measurement, chemical analysis, XPS, infrared spectroscopy after adsorption of pyridine and adsorption microcalorimetry of NH{sub 3} and SO{sub 2} probe molecules. All investigated mixed oxides are amphoteric and possess redox centers on their surface. Moreover, hydrothermal synthesis leads to catalysts with higher surface area and with better acid–base properties than classical coprecipitation method. Both Lewis and Brønsted acid sites are present on the surface of the mixed oxides. Compared to the other samples, the ZrO{sub 2}/TiO{sub 2} material appears to be the best candidate for further application in acid–base catalysis. - Graphical abstract: Mesoporous amorphous phase with a high surface area of titania zirconia mixed oxide obtained by hydrothermal preparation. - Highlights: • Three zirconia based catalysts and a reference were prepared by hydrothermal synthesis. • Mixed oxides present larger surface areas than the reference ZrO{sub 2}. • ZrO{sub 2}/TiO{sub 2} catalyst presents a mesoporous structure with high surface area. • ZrO{sub 2}/TiO{sub 2} catalyst presents simultaneously strong acidic and basic properties.

  16. Defects in solution-processed dithienylsilole-based small-molecule photovoltaic thin-films

    NASA Astrophysics Data System (ADS)

    Muntasir, Tanvir; Chaudhary, Sumit

    2016-01-01

    DTS-(FBTTh2)2 is a prominent solution-processable small-molecule donor for donor-acceptor bulk-heterojunction organic photovoltaics. Power conversion efficiency of DTS-(FBTTh2)2 based photovoltaic devices exceeds 8%. This paper reports on the distribution of sub-bandgap trap states in DTS-(FBTTh2)2. Trap states were probed using admittance spectroscopy and low-frequency capacitance-voltage profiling and analyzed using established theoretical models. Three distributions were revealed in the trap density of states energy spectra. Key observations were (1) thicker solution-processed films with higher drying time had 55% less traps than thinner films that dried relative faster (2) blending of DTS-(FBTTh2)2 with the acceptor PC70BM introduced traps at the center of the donor-acceptor interfacial bandgap. Charge carrier dynamics in DTS-(FBTTh2)2 based thin-films was also characterized using impedance spectroscopy.

  17. Vanadium oxide based materials: Synthesis, characterization and gas sensing properties

    NASA Astrophysics Data System (ADS)

    Ayesh, Samar I.

    In recent years, the demand for gas sensors based on safety and process control requirements has been expanding. The reason for such demand sterns from environmental and safety concerns since the toxic gases released from automobile exhausts and chemical plants can directly or indirectly pollute our environment and affect our health. Among the chemicals studied, nitrogen oxide (NOx) gases are among the most dangerous air pollutants. Transition metal oxide clusters (or polyoxometalates) provide an exciting opportunity for the design and synthesis of a new generation of materials for efficient NOx sensing. Polyoxometalates are an important and fast emerging class of compounds that exhibit many remarkable properties. Chapter 1 provides introduction and background of chemical sensors. It describes the need for gas sensors and the current status of research in the area of NOx gas sensors in particular. A description of polyoxmetalates and their relevance as potential novel gas sensor materials is also given. Chapter 2 describes the synthesis and characterization by FTIR spectroscopy, elemental analysis, thermogravimetric analysis, manganometric titration, bond valence sum calculation, temperature dependent magnetic properties studies, electron paramagnetic resonance, and complete single crystal X-ray diffraction analysis of newly prepared vanadium oxide based-systems that have been discovered during the course of this work. First, the system containing arrays of decavanadates networked by extensive hydrogen bonding with cyclic nitrogen bases are described. This is followed by the mixed-valence vanadium oxide cluster, [VV 13VIV3O42(Cl)]-7, containing a hitherto unknown vanadium oxide framework structure. Finally the synthesis of 3D-framework materials is described. These compounds have highly symmetrical closely related three-dimensional framework structures consisting vanadium oxide shells {V18O42(XO4)} linked via heterometallic atoms {M' = Cd, Zn} into three

  18. Methods for rapid frequency-domain characterization of leakage currents in silicon nanowire-based field-effect transistors.

    PubMed

    Roinila, Tomi; Yu, Xiao; Verho, Jarmo; Li, Tie; Kallio, Pasi; Vilkko, Matti; Gao, Anran; Wang, Yuelin

    2014-01-01

    Silicon nanowire-based field-effect transistors (SiNW FETs) have demonstrated the ability of ultrasensitive detection of a wide range of biological and chemical targets. The detection is based on the variation of the conductance of a nanowire channel, which is caused by the target substance. This is seen in the voltage-current behavior between the drain and source. Some current, known as leakage current, flows between the gate and drain, and affects the current between the drain and source. Studies have shown that leakage current is frequency dependent. Measurements of such frequency characteristics can provide valuable tools in validating the functionality of the used transistor. The measurements can also be an advantage in developing new detection technologies utilizing SiNW FETs. The frequency-domain responses can be measured by using a commercial sine-sweep-based network analyzer. However, because the analyzer takes a long time, it effectively prevents the development of most practical applications. Another problem with the method is that in order to produce sinusoids the signal generator has to cope with a large number of signal levels. This may become challenging in developing low-cost applications. This paper presents fast, cost-effective frequency-domain methods with which to obtain the responses within seconds. The inverse-repeat binary sequence (IRS) is applied and the admittance spectroscopy between the drain and source is computed through Fourier methods. The methods is verified by experimental measurements from an n-type SiNW FET. PMID:25161832

  19. Aroma characterization based on aromatic series analysis in table grapes

    PubMed Central

    Wu, Yusen; Duan, Shuyan; Zhao, Liping; Gao, Zhen; Luo, Meng; Song, Shiren; Xu, Wenping; Zhang, Caixi; Ma, Chao; Wang, Shiping

    2016-01-01

    Aroma is an important part of quality in table grape, but the key aroma compounds and the aroma series of table grapes remains unknown. In this paper, we identified 67 aroma compounds in 20 table grape cultivars; 20 in pulp and 23 in skin were active compounds. C6 compounds were the basic background volatiles, but the aroma contents of pulp juice and skin depended mainly on the levels of esters and terpenes, respectively. Most obviously, ‘Kyoho’ grapevine series showed high contents of esters in pulp, while Muscat/floral cultivars showed abundant monoterpenes in skin. For the aroma series, table grapes were characterized mainly by herbaceous, floral, balsamic, sweet and fruity series. The simple and visualizable aroma profiles were established using aroma fingerprints based on the aromatic series. Hierarchical cluster analysis (HCA) and principal component analysis (PCA) showed that the aroma profiles of pulp juice, skin and whole berries could be classified into 5, 3, and 5 groups, respectively. Combined with sensory evaluation, we could conclude that fatty and balsamic series were the preferred aromatic series, and the contents of their contributors (β-ionone and octanal) may be useful as indicators for the improvement of breeding and cultivation measures for table grapes. PMID:27487935

  20. Performance characterization of an insulator-based dielectrophoretic microdevice.

    PubMed

    Ozuna-Chacón, Sandra; Lapizco-Encinas, Blanca H; Rito-Palomares, Marco; Martínez-Chapa, Sergio O; Reyes-Betanzo, Claudia

    2008-08-01

    Dielectrophoresis (DEP), the motion of particles in nonuniform electric fields, is a nondestructive electrokinetic (EK) transport mechanism can be used to concentrate and separate bioparticles. Traditionally, DEP has been performed employing microelectrodes, an approach that is expensive due to the cost of microelectrode fabrication. An alternative is insulator-based DEP (iDEP), an inexpensive method where nonuniform electric fields are created with arrays of insulating structures. This study presents the effects of operating conditions on the dielectrophoretic behavior of polystyrene microparticles under iDEP. Experiments were performed employing microchannels containing insulating structures that worked as insulators. The parameters varied were pH (8-9) and conductivity (25-100 microS/cm) of the bulk medium, and the magnitude of the applied field (200-850 V/cm). Optimal operating conditions in terms of pH and conductivity were obtained, and the microdevice performance was characterized in terms of concentration factor and minimum electric field required (minimum energy consumption). This is the first report on improving iDEP processes when EOF is present. DEP and EOF have been studied extensively, however, this study integrates the effect of suspending medium characteristics on both EK phenomena. These findings will allow improving the performance of iDEP microdevices achieving the highest concentration fold with the lowest energy consumption. PMID:18654979

  1. Inhomogeneity Based Characterization of Distribution Patterns on the Plasma Membrane.

    PubMed

    Paparelli, Laura; Corthout, Nikky; Pavie, Benjamin; Wakefield, Devin L; Sannerud, Ragna; Jovanovic-Talisman, Tijana; Annaert, Wim; Munck, Sebastian

    2016-09-01

    Cell surface protein and lipid molecules are organized in various patterns: randomly, along gradients, or clustered when segregated into discrete micro- and nano-domains. Their distribution is tightly coupled to events such as polarization, endocytosis, and intracellular signaling, but challenging to quantify using traditional techniques. Here we present a novel approach to quantify the distribution of plasma membrane proteins and lipids. This approach describes spatial patterns in degrees of inhomogeneity and incorporates an intensity-based correction to analyze images with a wide range of resolutions; we have termed it Quantitative Analysis of the Spatial distributions in Images using Mosaic segmentation and Dual parameter Optimization in Histograms (QuASIMoDOH). We tested its applicability using simulated microscopy images and images acquired by widefield microscopy, total internal reflection microscopy, structured illumination microscopy, and photoactivated localization microscopy. We validated QuASIMoDOH, successfully quantifying the distribution of protein and lipid molecules detected with several labeling techniques, in different cell model systems. We also used this method to characterize the reorganization of cell surface lipids in response to disrupted endosomal trafficking and to detect dynamic changes in the global and local organization of epidermal growth factor receptors across the cell surface. Our findings demonstrate that QuASIMoDOH can be used to assess protein and lipid patterns, quantifying distribution changes and spatial reorganization at the cell surface. An ImageJ/Fiji plugin of this analysis tool is provided. PMID:27603951

  2. Dental hard tissue characterization using laser-based ultrasonics

    NASA Astrophysics Data System (ADS)

    Blodgett, David W.; Massey, Ward L.

    2003-07-01

    Dental health care and research workers require a means of imaging the structures within teeth in vivo. One critical need is the detection of tooth decay in its early stages. If decay can be detected early enough, the process can be monitored and interventional procedures, such as fluoride washes and controlled diet, can be initiated to help re-mineralize the tooth. Currently employed x-ray imaging is limited in its ability to visualize interfaces and incapable of detecting decay at a stage early enough to avoid invasive cavity preparation followed by a restoration. To this end, non-destructive and non-contact in vitro measurements on extracted human molars using laser-based ultrasonics are presented. Broadband ultrasonic waves are excited in the extracted sections by using a pulsed carbon-dioxide (CO2) laser operating in a region of high optical absorption in the dental hard tissues. Optical interferometric detection of the ultrasonic wave surface displacements in accomplished with a path-stabilized Michelson-type interferometer. Results for bulk and surface in-vitro characterization of caries are presented on extracted molars with pre-existing caries.

  3. Aroma characterization based on aromatic series analysis in table grapes.

    PubMed

    Wu, Yusen; Duan, Shuyan; Zhao, Liping; Gao, Zhen; Luo, Meng; Song, Shiren; Xu, Wenping; Zhang, Caixi; Ma, Chao; Wang, Shiping

    2016-01-01

    Aroma is an important part of quality in table grape, but the key aroma compounds and the aroma series of table grapes remains unknown. In this paper, we identified 67 aroma compounds in 20 table grape cultivars; 20 in pulp and 23 in skin were active compounds. C6 compounds were the basic background volatiles, but the aroma contents of pulp juice and skin depended mainly on the levels of esters and terpenes, respectively. Most obviously, 'Kyoho' grapevine series showed high contents of esters in pulp, while Muscat/floral cultivars showed abundant monoterpenes in skin. For the aroma series, table grapes were characterized mainly by herbaceous, floral, balsamic, sweet and fruity series. The simple and visualizable aroma profiles were established using aroma fingerprints based on the aromatic series. Hierarchical cluster analysis (HCA) and principal component analysis (PCA) showed that the aroma profiles of pulp juice, skin and whole berries could be classified into 5, 3, and 5 groups, respectively. Combined with sensory evaluation, we could conclude that fatty and balsamic series were the preferred aromatic series, and the contents of their contributors (β-ionone and octanal) may be useful as indicators for the improvement of breeding and cultivation measures for table grapes. PMID:27487935

  4. Characterization of porcine eyes based on autofluorescence lifetime imaging

    NASA Astrophysics Data System (ADS)

    Batista, Ana; Breunig, Hans Georg; Uchugonova, Aisada; Morgado, António Miguel; König, Karsten

    2015-03-01

    Multiphoton microscopy is a non-invasive imaging technique with ideal characteristics for biological applications. In this study, we propose to characterize three major structures of the porcine eye, the cornea, crystalline lens, and retina using two-photon excitation fluorescence lifetime imaging microscopy (2PE-FLIM). Samples were imaged using a laser-scanning microscope, consisting of a broadband sub-15 femtosecond (fs) near-infrared laser. Signal detection was performed using a 16-channel photomultiplier tube (PMT) detector (PML-16PMT). Therefore, spectral analysis of the fluorescence lifetime data was possible. To ensure a correct spectral analysis of the autofluorescence lifetime data, the spectra of the individual endogenous fluorophores were acquired with the 16-channel PMT and with a spectrometer. All experiments were performed within 12h of the porcine eye enucleation. We were able to image the cornea, crystalline lens, and retina at multiple depths. Discrimination of each structure based on their autofluorescence intensity and lifetimes was possible. Furthermore, discrimination between different layers of the same structure was also possible. To the best of our knowledge, this was the first time that 2PE-FLIM was used for porcine lens imaging and layer discrimination. With this study we further demonstrated the feasibility of 2PE-FLIM to image and differentiate three of the main components of the eye and its potential as an ophthalmologic technique.

  5. Synthesis, characterization and antimicrobial studies of Schiff base complexes

    NASA Astrophysics Data System (ADS)

    Zafar, Hina; Ahmad, Anis; Khan, Asad U.; Khan, Tahir Ali

    2015-10-01

    The Schiff base complexes, MLCl2 [M = Fe(II), Co(II), Ni(II), Cu(II) and Zn(II)] have been synthesized by the template reaction of respective metal ions with 2-acetylpyrrole and 1,3-diaminopropane in 1:2:1 M ratio. The complexes have been characterized by elemental analyses, ESI - mass, NMR (1H and 13C), IR, XRD, electronic and EPR spectral studies, magnetic susceptibility and molar conductance measurements. These studies show that all the complexes have octahedral arrangement around the metal ions. The molar conductance measurements of all the complexes in DMSO indicate their non-electrolytic nature. The complexes were screened for their antibacterial activity in vitro against Gram-positive (Streptococcus pyogenes) and Gram-negative (Klebsiella pneumoniae) bacteria. Among the metal complexes studied the copper complex [CuLCl2], showed highest antibacterial activity nearly equal to standard drug ciprofloxacin. Other complexes also showed considerable antibacterial activity. The relative order of activity against S. Pyogenes is as Cu(II) > Zn(II) > Co(II) = Fe(II) > Ni(II) and with K. Pneumonia is as Cu(II) > Co(II) > Zn(II) > Fe(II) > Ni(II).

  6. Synthesis and Characterizations of Melamine-Based Epoxy Resins

    PubMed Central

    Ricciotti, Laura; Roviello, Giuseppina; Tarallo, Oreste; Borbone, Fabio; Ferone, Claudio; Colangelo, Francesco; Catauro, Michelina; Cioffi, Raffaele

    2013-01-01

    A new, easy and cost-effective synthetic procedure for the preparation of thermosetting melamine-based epoxy resins is reported. By this innovative synthetic method, different kinds of resins can be obtained just by mixing the reagents in the presence of a catalyst without solvent and with mild curing conditions. Two types of resins were synthesized using melamine and a glycidyl derivative (resins I) or by adding a silane derivative (resin II). The resins were characterized by means of chemical-physical and thermal techniques. Experimental results show that all the prepared resins have a good thermal stability, but differ for their mechanical properties: resin I exhibits remarkable stiffness with a storage modulus value up to 830 MPa at room temperature, while lower storage moduli were found for resin II, indicating that the presence of silane groups could enhance the flexibility of these materials. The resins show a pot life higher than 30 min, which makes these resins good candidates for practical applications. The functionalization with silane terminations can be exploited in the formulation of hybrid organic-inorganic composite materials. PMID:24013372

  7. Processing, characterization and properties of oxide based nanocomposites

    NASA Astrophysics Data System (ADS)

    Bhaduri, Sutapa

    The synthesis, characterization and mechanical properties of oxide based nanocomposites are reported in this dissertation. Two binary systems are studied: Alsb2Osb3-MgO and Alsb2Osb3-ZrOsb2. Alsb2Osb3-MgO was chosen because of its relatively large field of solid solubilities at a moderate temperature. On the other hand, Alsb2Osb3-ZrOsb2 was chosen because it shows minimal solid solubility of the constituents. A novel "Auto Ignition" process using suitable fuels and oxidizers was utilized in the synthesis of nanocomposites and solid solutions. Thermodynamic calculations were carried out in predicting end point adiabatic temperatures (Tsbad) for each composition in both systems. Combustion temperatures were experimentally measured by means of a data acquisition system. Characterizations of the powders were carried out by x-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive analysis (EDAX) and differential thermal analysis (DTA). Heat treatment experiments were carried out to study the grain growth behavior. A hot isostatic pressing (HIP) model was developed for the present nanoceramics. Input parameters were carefully chosen for such nanomaterials. The as-synthesized nanocrystalline powders were consolidated to near theoretical density by hot isostatic pressing (HIPing) while retaining fine grain size. The experimental results were compared with the predictions of the model. Mechanical properties, such as room temperature toughness, low temperatures well as high temperature hardness, were determined for both systems. Room temperature hardness values were (2.89-7.79) GPa and fracture toughness was between 2.7 and 5.82 MPa.msp{1/2} for various compositions in the Alsb2Osb3-MgO system. Room temperature hardness values were between 5.33 and 8.71 GPa and fracture toughness values ranged from (5.3-9.62) MPa.msp{1/2} for various compositions in the Alsb2Osb3-ZrOsb2 system. Nanoindentation experiments were carried out to further explore the room

  8. Synthesis and characterization of nanostructured palladium-based alloy electrocatalysts

    NASA Astrophysics Data System (ADS)

    Sarkar, Arindam

    Low temperature fuel cells like proton exchange membrane fuel cells (PEMFC) are expected to play a crucial role in the future hydrogen economy, especially for transportation applications. These electrochemical devices offer significantly higher efficiency compared to conventional heat engines. However, use of exotic and expensive platinum as the electrocatalyst poses serious problems for commercial viability. In this regard, there is an urgent need to develop low-platinum or non-platinum electrocatalysts with electrocatalytic activity for the oxygen reduction reaction (ORR) superior or comparable to that of platinum. This dissertation first investigates non-platinum, palladium-based alloy electrocatalysts for ORR. Particularly, Pd-M (M = Mo and W) alloys are synthesized by a novel thermal decomposition of organo-metallic precursors. The carbon-supported Pd-M (M = Mo, W) electrocatalyts are then heat treated up to 900°C in H2 atmosphere and investigated for their phase behavior. Cyclic voltammetry (CV) and rotating disk electrode (RDE) measurements reveal that the alloying of Pd with Mo or W significantly enhances the catalytic activity for ORR as well as the stability (durability) of the electrocatalysts. Additionally, both the alloy systems exhibit high tolerance to methanol, which is particularly advantageous for direct methanol fuel cells (DMFC). The dissertation then focuses on one-pot synthesis of carbon-supported multi-metallic Pt-Pd-Co nanoalloys by a rapid microwave-assisted solvothermal (MW-ST) method. The multi-metallic alloy compositions synthesized by the MW-ST method show much higher catalytic activity for ORR compared to their counterparts synthesized by the conventional borohydride reduction method. Additionally, a series of Pt encapsulated Pd-Co nanoparticle electrocatalysts are synthesized by the MW-ST method and characterized to understand their phase behavior, surface composition, and electrocatalytic activity for ORR. Finally, the dissertation

  9. Boron-based nanostructures: Synthesis, functionalization, and characterization

    NASA Astrophysics Data System (ADS)

    Bedasso, Eyrusalam Kifyalew

    Boron-based nanostructures have not been explored in detail; however, these structures have the potential to revolutionize many fields including electronics and biomedicine. The research discussed in this dissertation focuses on synthesis, functionalization, and characterization of boron-based zero-dimensional nanostructures (core/shell and nanoparticles) and one-dimensional nanostructures (nanorods). The first project investigates the synthesis and functionalization of boron-based core/shell nanoparticles. Two boron-containing core/shell nanoparticles, namely boron/iron oxide and boron/silica, were synthesized. Initially, boron nanoparticles with a diameter between 10-100 nm were prepared by decomposition of nido-decaborane (B10H14) followed by formation of a core/shell structure. The core/shell structures were prepared using the appropriate precursor, iron source and silica source, for the shell in the presence of boron nanoparticles. The formation of core/shell nanostructures was confirmed using high resolution TEM. Then, the core/shell nanoparticles underwent a surface modification. Boron/iron oxide core/shell nanoparticles were functionalized with oleic acid, citric acid, amine-terminated polyethylene glycol, folic acid, and dopamine, and boron/silica core/shell nanoparticles were modified with 3-(amino propyl) triethoxy silane, 3-(2-aminoethyleamino)propyltrimethoxysilane), citric acid, folic acid, amine-terminated polyethylene glycol, and O-(2-Carboxyethyl)polyethylene glycol. A UV-Vis and ATR-FTIR analysis established the success of surface modification. The cytotoxicity of water-soluble core/shell nanoparticles was studied in triple negative breast cancer cell line MDA-MB-231 and the result showed the compounds are not toxic. The second project highlights optimization of reaction conditions for the synthesis of boron nanorods. This synthesis, done via reduction of boron oxide with molten lithium, was studied to produce boron nanorods without any

  10. Enhanced centrifuge-based approach to powder characterization

    NASA Astrophysics Data System (ADS)

    Thomas, Myles Calvin

    Many types of manufacturing processes involve powders and are affected by powder behavior. It is highly desirable to implement tools that allow the behavior of bulk powder to be predicted based on the behavior of only small quantities of powder. Such descriptions can enable engineers to significantly improve the performance of powder processing and formulation steps. In this work, an enhancement of the centrifuge technique is proposed as a means of powder characterization. This enhanced method uses specially designed substrates with hemispherical indentations within the centrifuge. The method was tested using simulations of the momentum balance at the substrate surface. Initial simulations were performed with an ideal powder containing smooth, spherical particles distributed on substrates designed with indentations. The van der Waals adhesion between the powder, whose size distribution was based on an experimentally-determined distribution from a commercial silica powder, and the indentations was calculated and compared to the removal force created in the centrifuge. This provided a way to relate the powder size distribution to the rotational speed required for particle removal for various indentation sizes. Due to the distinct form of the data from these simulations, the cumulative size distribution of the powder and the Hamaker constant for the system were be extracted. After establishing adhesion force characterization for an ideal powder, the same proof-of-concept procedure was followed for a more realistic system with a simulated rough powder modeled as spheres with sinusoidal protrusions and intrusions around the surface. From these simulations, it was discovered that an equivalent powder of smooth spherical particles could be used to describe the adhesion behavior of the rough spherical powder by establishing a size-dependent 'effective' Hamaker constant distribution. This development made it possible to describe the surface roughness effects of the entire

  11. Characterization of a GEM-based fast neutron detector

    NASA Astrophysics Data System (ADS)

    Esposito, B.; Marocco, D.; Villari, R.; Murtas, F.; Rodionov, R.

    2014-03-01

    The neutron efficiency of a Gas Electron Multiplier (GEM)-based detector designed for fast neutron measurements in fusion devices was determined through the combined use of Monte Carlo (MCNPX) calculations and analysis of deuterium-deuterium and deuterium-tritium neutron irradiation experiments. The detector, characterized by a triple GEM structure flushed with a Ar/CO2/CF4 - 45/15/40 gas mixture, features a digital read-out system and has two sub-units for the detection of 2.5+14 MeV neutrons and 14 MeV neutrons (UDD and UDT, respectively). The pulse height spectra (PHS) determined from the curves of experimental efficiency as a function of the detector's high voltage (HV) and the MCNPX-simulated PHS were compared using a fitting routine that finds the best match between the experimental and simulated PHS by assuming a parametric model for the relation between HV (that determines the detector's gain) and the energy deposited in the gas. This led to express the experimental neutron efficiency as a function of the discrimination level set on the deposited energy (energy threshold). The detector sensitivity to γ-rays was also analyzed and the operational range in which the γ-ray contribution to the signal is not negligible was determined. It is found that this detector can reach a maximum neutron efficiency of ~1×10-3 counts/n at 2.5 MeV (UDD sub-unit) and of ~4×10-3 counts/n at 14 MeV (UDT and UDD sub-units).

  12. Molecular based subtyping of feline mammary carcinomas and clinicopathological characterization.

    PubMed

    Soares, Maria; Madeira, Sara; Correia, Jorge; Peleteiro, Maria; Cardoso, Fátima; Ferreira, Fernando

    2016-06-01

    Molecular classification of feline mammary carcinomas (FMC) from which specific behavioral patterns may be estimated has potential applications in veterinary clinical practice and in comparative oncology. In this perspective, the main goal of this study was to characterize both the clinical and the pathological features of the different molecular phenotypes found in a population of FMC (n = 102), using the broadly accepted IHC-based classification established by St. Gallen International Expert Consensus panel. The luminal B/HER2-negative subtype was the most common (29.4%, 30/102) followed by luminal B/HER2-positive subtype (19.6%, 20/102), triple negative basal-like (16.7%, 17/102), luminal A (14.7%, 15/102), triple negative normal-like (12.7%, 13/102) and finally, HER2-positive subtype (6.9%, 7/102). Luminal A subtype was significantly associated with smaller tumors (p = 0.024) and with well differentiated ones (p < 0.001), contrasting with the triple negative basal-like subtype, that was associated with larger and poorly differentiated tumors (p < 0.001), and with the presence of necrotic areas in the tumoral lesion (p = 0.003). In the survival analysis, cats with Luminal A subtype presented the highest survival time (mean OS = 943.6 days) and animals with triple negative basal-like subtype exhibited the lowest survival time (OS mean = 368.9 days). Moreover, two thirds (64%, 32/50) of the queens with multiple primary tumors showed different molecular subtypes in each carcinoma, revealing that all independent lesions should be analyzed in order to improve the clinical management of animals. Finally, the similarities between the subtypes of feline mammary tumors and human breast cancer, reveal that feline can be a valuable model for comparative studies. PMID:27212699

  13. Preparation and Characterization of N-Halamine-based Antimicrobial Fillers

    PubMed Central

    Padmanabhuni, Revathi V.; Luo, Jie; Cao, Zhengbing; Sun, Yuyu

    2012-01-01

    The purpose of this study was to demonstrate that the surface of CaCO3 fillers could be coated with an N-halamine based fatty acid to make the filler surface organophilic and accomplish antibacterial activity simultaneously, rendering the resulting polymer-filler composites antimicrobial. Thus, a new bi-functional compound, 4, 4 -Dimethyl hydantoin-undecanoic acid (DMH-UA), was synthesized by treating the potassium salt of dimethyl hydantoin (DMH) with 11-bromoundecanoic acid (BUA). Upon chlorination treatment with diluted bleach, DMH-UA was transformed into 3-chloro-4, 4-dimethyl hydantoin- undecanoic acid (Cl-DMH-UA). Alternatively, DMH-UA could be coated onto the surface of CaCO3 to obtain the corresponding calcium salt, 4, 4-dimethyl hydantoin-undecanoic acid-calcium carbonate (DMH-UA-CaCO3). In the presence of diluted chlorine bleach, the coated DMH-UA on the surface of CaCO3 was transformed into Cl-DMH-UA, leading to the formation of Cl-DMH-UA-CaCO3. The reactions were characterized with FT-IR, NMR, UV, DSC and SEM analyses. Both Cl-DMH-UA and Cl-DMH-UA-CaCO3 were used as antimicrobial additives for cellulose acetate (CA). The antimicrobial efficacy of the resulting samples was evaluated against both Escherichia coli (Gram-negative bacteria) and Staphylococcus aureus (Gram-positive bacteria). It was found that with the same additive content, CA samples with Cl-DMH-UA-CaCO3 and Cl-DMH-UA had very similar antimicrobial and biofilm-controlling activity, but the former released less active chlorine into the surrounding environment than the latter. PMID:22942559

  14. Determination of the valence band offset of MOVPE-grown In0.48Ga0.52P/GaAs multiple quantum wells by admittance spectroscopy

    NASA Astrophysics Data System (ADS)

    Ghezzi, Carlo; Magnanini, Renato; Parisini, Antonella; Tarricone, Luciano; Gombia, Enos; Longo, Massimo

    2008-03-01

    The valence band discontinuity of the lattice matched In0.48Ga0.52P/GaAs heterostructure was determined through a careful analysis of the temperature and frequency dependence of the admittance of p+/MQW/n+ structures, formed by a nominally undoped InGaP/GaAs multiple quantum well region, interposed between p+ and n+ GaAs layers. The heterostructures were grown through metal organic vapor phase epitaxy by using tertiary butyl arsine and tertiary butyl phosphine as alternative precursors for the V-group elements. The growth conditions were optimized for obtaining sharp interfaces and negligible ordering effects in the cation sublattice. Accounting for the temperature dependence of the Fermi energy and the calculated confining energy (10meV) of the heavy holes in the wells, a valence band offset ΔEV=(356±5)meV was derived from the temperature variation of the resonance frequency at which the isothermal conductance over frequency G(ω)/ω curves show a maximum. The experimental uncertainty of this result is significantly low if compared with the wide range (240-400meV) of the previously reported ΔEV values. By considering the band gap difference between InGaP and GaAs, a conduction band offset ΔEC=119meV was estimated. The accuracy of the experimental procedure and the reliability of the main assumptions of the admittance spectroscopy measurements were accurately checked. The obtained results were discussed in light of the large and growing amount of literature data by taking into account the influence of the growth conditions on the physical properties of the InGaP/GaAs quantum wells.

  15. Fabrication, Characterization, and Applications of Graphene-based Flexible Films

    NASA Astrophysics Data System (ADS)

    Naik, Gautam

    while maintaining its structural integrity is essential. A method for thermal reduction of flexible graphene oxide films under stress confinement is described. Reduction of graphene oxide flexible films is carried out in a MTS testing machine equipped with a controlled atmosphere furnace. The reduced films show higher carbon-to-oxygen ratio and an increase in conductivity by over five orders in magnitude. An electromechanical application of these reduced graphene oxide films for strain sensing is also demonstrated, with high and tunable gauge factors, which are three orders of magnitude higher than conventional metal foil strain gauges. A mechanism and model to explain the strain sensing is also described. Lastly, quantification of the degree of photoreduction and characterization of thermal properties of graphene-based flexible films is conducted. The temperature distribution on the surface of the graphene oxide flexible film is recorded using an infrared thermal camera. Effective reduction using a laser is achieved in a very short duration at low power and temperature. The thermal properties are calculated using the transient temperature response, and are found to be orders of magnitude lower than pristine graphene. The photoreduction method is a promising route for roll-to-roll production of reduced graphene oxide flexible films.

  16. Synthesis and characterization of new chitosan-based Schiff base compounds.

    PubMed

    Gavalyan, Vasak B

    2016-07-10

    Chitin (Cn) was extracted from the armors of crustaceans Astacus leptodactylus (Lake Sevan, Armenia) and then converted to chitosan (Cs), its deacetylated derivative. Novel Schiff bases (CsSB) were synthesized by interaction of Cs with 4-(2-chloroethyl)benzaldehyde (aldehyde-1) and 4-(2-bromoethyl)benzaldehyde (aldehyde-2), and underwent dehydrohalogenation, under basic conditions (10°C), to yield respective vinyl derivatives. All newly synthesized compounds were structurally characterized by solubility tests, elemental analysis, infrared spectroscopy (FTIR), thermogravimetry (TGA), proton nuclear magnetic resonance ((1)H NMR), and X-ray diffraction (XRD). PMID:27106149

  17. Characterization and Modeling of Segmental Dynamics in Silicone Based Nanocomposites

    SciTech Connect

    Maxwell, R S; Baumann, T; Gee, R; Maiti, A; Patel, M; Lewicki, J

    2009-03-27

    The addition of nano-particles with novel chemical, optical, or barrier properties further opens the door to the development of so-called multifunctional materials (1). Key to developing robust, tailored composites is a detailed understanding of the structural contributions to the engineering properties of the composite and how they may change with time in harsh service conditions. The segmental dynamics and local order underlie much of the fundamental physics that influence the performance of elastomers and can serve as important diagnostics for reinforcement and other fundamental properties (e.g., network topology, cross-link density, the number and distance between chemical and physical (entanglements) cross-links, the type and volume fraction of filler) and thus provide a route to this fundamental understanding. {sup 1}H MQ-NMR spectroscopy has shown the ability to provide more reliable and quantitative information regarding the elastomer network structure and heterogeneities (2). {sup 1}H MQ-NMR methods allow for the measurement of absolute residual dipolar couplings (<{Omega}{sub d}>) and thus the segmental/cooperative dynamics Thus, the MQ-NMR method allows for the direct measure of network topology and in many cases, filler-particle interactions. The ability of MD methods to uncover structural motifs and dynamics at the atomistic scale is well known. In polymer systems, however, the relationship to bulk material properties can be somewhat tenuous due to often limited number of atoms and short time durations that can be studied. Extending these MD simulations to large assemblies of atoms and extending them to longer times using state of the art computational resources has allowed us to probe some useful relationships. MD provides static and dynamic properties for a collection of particles that allow atomic scale insights that are difficult to gain otherwise. We have been exploiting these methods to characterize the effects of network structure and filler

  18. Laser-Based Characterization of Nuclear Fuel Plates

    SciTech Connect

    James A. Smith; David L. Cottle; Barry H. Rabin

    2013-07-01

    Ensuring the integrity of fuel-clad and clad-clad bonding in nuclear fuels is important for safe reactor operation and assessment of fuel performance, yet the measurement of bond strengths in actual fuels has proved challenging. The laser shockwave technique (LST) originally developed to characterize structural adhesion in composites is being employed to characterize interface strength in a new type of plate fuel being developed at Idaho National Laboratory (INL). LST is a non-contact method that uses lasers for the generation and detection of large-amplitude acoustic waves and is well suited for application to both fresh and irradiated nuclear-fuel plates. This paper will report on initial characterization results obtained from fresh fuel plates manufactured by different processes, including hot isostatic pressing, friction stir welding, and hot rolling.

  19. Laser-based characterization of nuclear fuel plates

    SciTech Connect

    Smith, James A.; Cottle, Dave L.; Rabin, Barry H.

    2014-02-18

    Ensuring the integrity of fuel-clad and clad-clad bonding in nuclear fuels is important for safe reactor operation and assessment of fuel performance, yet the measurement of bond strengths in actual fuels has proved challenging. The laser shockwave technique (LST) originally developed to characterize structural adhesion in composites is being employed to characterize interface strength in a new type of plate fuel being developed at Idaho National Laboratory (INL). LST is a non-contact method that uses lasers for the generation and detection of large-amplitude acoustic waves and is well suited for application to both fresh and irradiated nuclear-fuel plates. This paper will report on initial characterization results obtained from fresh fuel plates manufactured by different processes, including hot isostatic pressing, friction stir welding, and hot rolling.

  20. MEMS-based shear characterization of soft hydrated samples

    NASA Astrophysics Data System (ADS)

    Higgs, Gadryn C.; Simmons, Chelsey S.; Gao, Yingning; Fried, Andrew T.; Park, Sung-Jin; Chung, Cindy; Pruitt, Beth L.

    2013-08-01

    We have designed, fabricated, calibrated and tested actuators for shear characterization to assess microscale shear properties of soft substrates. Here, we demonstrate characterization of dry silicone and hydrated polyethylene glycol. Microscale tools, including atomic force microscopes and nanoindenters, often have limited functionality in hydrated environments. While electrostatic comb-drive actuators are particularly susceptible to moisture damage, through chemical vapor deposition of hexamethyldisiloxane, we increase the hydrophobicity of our electrostatic devices to a water contact angle 90 ± 3°. With this technique, we determine the effective shear stiffness of both dry and hydrated samples for a range of soft substrates. Using computational and analytical models, we compare our empirically determined effective shear stiffness with existing characterization methods, rheology, and nanoindentation, for samples with shear moduli ranging from 5-320 kPa. This work introduces a new approach for microscale assessment of synthetic materials that can be used on biological materials for basic and applied biomaterials research.

  1. MEMS-based shear characterization of soft hydrated samples

    PubMed Central

    Gao, Yingning; Fried, Andrew; Park, Sung-Jin; Chung, Cindy; Pruitt, Beth L.

    2013-01-01

    We have designed, fabricated, calibrated and tested actuators for shear characterization to assess microscale shear properties of soft substrates. Here we demonstrate characterization of dry silicone and hydrated polyethelyne glycol. Microscale tools, including atomic force microscopes and nanoindenters, often have limited functionality in hydrated environments. While electrostatic comb-drive actuators are particularly susceptible to moisture damage, through chemical vapor deposition of hexamethyldisiloxane, we increase the hydrophobicity of our electrostatic devices to a water contact angle 90 ± 3°. With this technique we determine the effective shear stiffness of both dry and hydrated samples for a range of soft substrates. Using computational and analytical models, we compare our empirically determined effective shear stiffness with existing characterization methods, rheology and nanoindentation, for samples with shear moduli ranging from 5-320 kPa. This work introduces a new approach for microscale assessment of synthetic materials that can be used on biological materials for basic and applied biomaterials research. PMID:24187440

  2. Synthesis, characterization and biological activity of Schiff bases based on chitosan and arylpyrazole moiety.

    PubMed

    Salama, Hend E; Saad, Gamal R; Sabaa, Magdy W

    2015-08-01

    The Schiff bases of chitosan were synthesized by the reaction of chitosan with 3-(4-substituted-phenyl)-1-phenyl-1H-pyrazole-4-carbaldehyde. The structure of the prepared chitosan derivatives was characterized by FT-IR spectroscopy, elemental analysis, and X-ray diffraction studies and thermogravimetric analysis (TG). The results show that the specific properties of Schiff bases of chitosan can be altered by modifying the molecular structures with proper substituent groups.TG results reveal that the thermal stability of the prepared chitosan Schiff bases was lower than chitosan. The activation energy of decomposition was calculated using Coats-Redfern model. The antimicrobial activity of chitosan and Schiff bases of chitosan were investigated against Streptococcus pneumonia, Bacillis subtilis, Escherichia coli (as examples of bacteria) and Aspergillus fumigatus, Geotricum candidum and Syncephalastrum recemosum (as examples of fungi). The results indicated that the antimicrobial activity of the Schiff bases was stronger than that of chitosan and was dependent on the substituent group. The activity of un-substituted arylpyrazole chitosan derivative toward the investigated bacteria and fungi species was better than the other derivatives. PMID:26067768

  3. Characterization of a Fabry - Perot - Based electrooptic Modulator

    NASA Technical Reports Server (NTRS)

    Banks, C.; Yelleswarapu, C.; Sharma, A.; Frazier, D.; Penn, B.; Abdeldayem, H.; Rose, M. Franklin (Technical Monitor)

    2000-01-01

    An electrooptic modulator using a thin slice of LiNbO3 within the cavity of a Fabry-Perot interferometer is designed and fabricated. The modulator is operated with 633 nm light from a He-Ne laser. Results related to characterization of this modulator are presented.

  4. Transuranic contaminated waste form characterization and data base

    SciTech Connect

    Kniazewycz, B.G.; McArthur, W.C.

    1980-07-01

    This volume contains appendices A to F. The properties of transuranium (TRU) radionuclides are described. Immobilization of TRU wastes by bituminization, urea-formaldehyde polymers, and cements is discussed. Research programs at DOE facilities engaged in TRU waste characterization and management studies are described.

  5. Synthesis and characterization of iron based nanoparticles for novel applications

    NASA Astrophysics Data System (ADS)

    Khurshid, Hafsa

    The work in this thesis has been focused on the fabrication and characterization of iron based nanoparticles with controlled size and morphology with the aim: (i) to investigate their properties for potential applications in MICR toners and biomedical field and (ii) to study finite size effects on the magnetic properties of the nanoparticles. For the biomedical applications, core/shell structured iron/iron-oxide and hollow shell nanoparticles were synthesized by thermal decomposition of iron organometallic compounds [Fe(CO)5] at high temperature. Core/shell structured iron/iron-oxide nanoparticles have been prepared in the presence of oleic acid and oleylamine. Particle size and composition was controlled by varying the reaction parameters during synthesis. The as-made particles are hydrophobic and not dispersible in water. Water dispersibility was achieved by ligand exchange a with double hydrophilic diblock copolymer. Relaxometery measurements of the transverse relaxation time T2 of the nanoparticles solution at 3 Tesla confirm that the core/shell nanoparticles are an excellent MRI contrast agent using T2 weighted imaging sequences. In comparison to conventionally used iron oxide nanoparticles, iron/iron-oxide core/shell nanoparticles offer four times stronger T2 shortening effect at comparable core size due to their higher magnetization. The magnetic properties were studied as a function of particle size, composition and morphology. Hollow nanostructures are composed of randomly oriented grains arranged together to make a shell layer and make an interesting class of materials. The hollow morphology can be used as an extra degree of freedom to control the magnetic properties. Owing to their hollow morphology, they can be used for the targeted drug delivery applications by filling the drug inside their cavity. For the magnetic toners applications, particles were synthesized by chemically reducing iron salt using sodium borohydride and then coated with polyethylene

  6. Synthesis and characterization of a new aluminium-based compound.

    PubMed

    Pascual-Cosp, José; Artiaga, Ramón; Corpas-Iglesias, Francisco; Benítez-Guerrero, Mónica

    2009-08-28

    A new aluminium polynuclear crystalline species, Al(13)(OH)(30)(H(2)O)(15)Cl(9) has been synthesized and characterized. It is a particular case of the Al(13)(OH)(30-y)(H(2)O)(18-x)Cl(9) x zH(2)O family. It has been obtained from aluminium waste cans treated with HCl solution in strong acid media, followed by an ageing period. The crystalline structure of the complex was determined by XRD spectroscopy. Twelve reflections were found and indexed with the DICVOL04 software. Morphologically, a flattened preferred orientation was observed by SEM and FESEM. The chemical structure was studied by several absorption spectroscopy techniques: FTIR, ATR-FTIR and Raman dispersion spectroscopy. The coordination of the aluminium nuclei was determined by Al-MAS-NMR. Only octahedral sites were observed. Thermal characterization of the compound was performed by evolved gas analysis (EGA) coupled to simultaneous TGA-DSC. PMID:19655063

  7. Electrical characterization of MEH-PPV based Schottky diodes

    NASA Astrophysics Data System (ADS)

    Nimith, K. M.; Satyanarayan, M. N.; Umesh, G.

    2016-05-01

    MEH-PPV Schottky diodes with and without Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS) have been fabricated and characterized. The highlight of this work is that all the fabrication and characterization steps had been carried out in the ambient conditions and the device fabrication was done without any UV-Ozone surface treatment of ITO anodes. Current Density-Voltage characteristics shows that the addition of hole injection layer (HIL) enhances the charge injection into the polymer layer by reducing the energy barrier across the Indium Tin Oxide (ITO)-Organic interface. The rectification ratio increases to 2.21 from 0.76 at 5V for multilayer devices compared to single layer devices. Further we investigated the effect of an alkali metal fluoride (LiF) by inserting a thin layer in between the organic layer and Aluminum (Al) cathode. The results of these investigations will be discussed in detail.

  8. Characterization of mirror-based modulation-averaging structures.

    PubMed

    Komljenovic, Tin; Babić, Dubravko; Sipus, Zvonimir

    2013-05-10

    Modulation-averaging reflectors have recently been proposed as a means for improving the link margin in self-seeded wavelength-division multiplexing in passive optical networks. In this work, we describe simple methods for determining key parameters of such structures and use them to predict their averaging efficiency. We characterize several reflectors built by arraying fiber-Bragg gratings along a segment of an optical fiber and show very good agreement between experiments and theoretical models. PMID:23669835

  9. Multifractal characterization of water soluble copper phthalocyanine based films surfaces

    NASA Astrophysics Data System (ADS)

    Ţălu, Ştefan; Stach, Sebastian; Mahajan, Aman; Pathak, Dinesh; Wagner, Tomas; Kumar, Anshul; Bedi, R. K.; Ţălu, Mihai

    2014-07-01

    This paper presents a multifractal approach to characterize the structural complexity of 3D surface roughness of CuTsPc films on the glass and quartz substrate, obtained with atomic force microscopy (AFM) analysis. CuTsPc films prepared by drop cast method were investigated. CuTsPc films surface roughness was studied by AFM in tapping-mode™, in an aqueous environment, on square areas of 100 μm2 and 2500 μm2. A detailed methodology for CuTsPc films surface multifractal characterization, which may be applied for AFM data, was also presented. Analysis of surface roughness revealed that CuTsPc films have a multifractal geometry at various magnifications. The generalized dimension D q and the singularity spectrum f( α) provided quantitative values that characterize the local scale properties of CuTsPc films surface morphology at nanometer scale. Multifractal analysis provides different yet complementary information to that offered by traditional surface statistical parameters.

  10. New Microwave-Based Missions Applications for Rainfed Crops Characterization

    NASA Astrophysics Data System (ADS)

    Sánchez, N.; Lopez-Sanchez, J. M.; Arias-Pérez, B.; Valcarce-Diñeiro, R.; Martínez-Fernández, J.; Calvo-Heras, J. M.; Camps, A.; González-Zamora, A.; Vicente-Guijalba, F.

    2016-06-01

    A multi-temporal/multi-sensor field experiment was conducted within the Soil Moisture Measurement Stations Network of the University of Salamanca (REMEDHUS) in Spain, in order to retrieve useful information from satellite Synthetic Aperture Radar (SAR) and upcoming Global Navigation Satellite Systems Reflectometry (GNSS-R) missions. The objective of the experiment was first to identify which radar observables are most sensitive to the development of crops, and then to define which crop parameters the most affect the radar signal. A wide set of radar variables (backscattering coefficients and polarimetric indicators) acquired by Radarsat-2 were analyzed and then exploited to determine variables characterizing the crops. Field measurements were fortnightly taken at seven cereals plots between February and July, 2015. This work also tried to optimize the crop characterization through Landsat-8 estimations, testing and validating parameters such as the leaf area index, the fraction of vegetation cover and the vegetation water content, among others. Some of these parameters showed significant and relevant correlation with the Landsat-derived Normalized Difference Vegetation Index (R>0.60). Regarding the radar observables, the parameters the best characterized were biomass and height, which may be explored for inversion using SAR data as an input. Moreover, the differences in the correlations found for the different crops under study types suggested a way to a feasible classification of crops.

  11. Ensemble-based characterization of uncertain environmental features

    NASA Astrophysics Data System (ADS)

    Wójcik, Rafał; McLaughlin, Dennis; Alemohammad, Seyed Hamed; Entekhabi, Dara

    2014-08-01

    This paper considers the characterization of uncertain spatial features that cannot be observed directly but must be inferred from noisy measurements. Examples of interest in environmental applications include rainfall patterns, solute plumes, and geological features. We formulate the characterization process as a Bayesian sampling problem and solve it with a non-parametric version of importance sampling. All images are concisely described with a small number of image attributes. These are derived from a multidimensional scaling procedure that maps high dimensional vectors of image pixel values to much lower dimensional vectors of attribute values. The importance sampling procedure is carried out entirely in terms of attribute values. Posterior attribute probabilities are derived from non-parametric estimates of the attribute likelihood and proposal density. The likelihood is inferred from an archive of noisy operational images that are paired with more accurate ground truth images. Proposal samples are generated from a non-stationary multi-point statistical algorithm that uses training images to convey distinctive feature characteristics. To illustrate concepts we carry out a virtual experiment that identifies rainy areas on the Earth's surface from either one or two remote sensing measurements. The two sensor case illustrates the method's ability to merge measurements with different error properties. In both cases, the importance sampling procedure is able to identify the proposals that most closely resemble a specified true image.

  12. Electrical characteristics of gadolinium gallium oxide/gallium oxide insulators on GaAs and In0.53Ga0.47As in metal-oxide-semiconductor field effect transistors - admittance and subthreshold characteristics

    NASA Astrophysics Data System (ADS)

    Paterson, G. W.; Bentley, S. J.; Holland, M. C.; Thayne, I. G.; Long, A. R.

    2011-09-01

    The admittances and subthreshold characteristics of capacitors and MOSFETs on buried InxGa1-xAs channel wafers with a dielectric stack of Gd0.25Ga0.15O0.6/Ga2O3 deposited on GaAs and In0.53Ga0.47As are reported. Both the GaAs and InGaAs interface samples show admittance characteristics indicative of the presence of defect states within the oxide, in agreement with previously reported data from the same oxides on n+ substrates. The interface state model is applied to the admittance data to extract an apparent interface state density (Dit) that includes interface and oxide states. The Dit profiles are very different and have pronounced effects on the device performance. The device subthreshold swings (SS) at low source-drain voltages are also used to extract an apparent Dit. A simple method is used to estimate the Fermi-level position within the bandgap (Et) at threshold, and the resulting Dit(Et) are found to be in good agreement with the admittance data. The importance of proper interpretation of SS and Dit in general and in GaAs interface devices in particular is emphasized. A model that accounts for the logarithmic sweep rate dependence of the extracted Dit due to the presence of oxide states is reported and used to estimate their density from SS measurements. The implications of the band parameters of an oxide with defect states within it for the comparison of different oxides on the same substrate and the issues around the comparison of results in general are discussed.

  13. Characterization and supply of coal-based fuels

    SciTech Connect

    Not Available

    1989-06-01

    Contract objectives are as follows: Develop fuel specifications to serve combustor requirements. Select coals having appropriate compositional and quality characteristics as well as an economically attractive reserve base; Provide quality assurance for both the parent coals and the fuel forms; and deliver premium coal-based fuels to combustor developers as needed for their contract work. Progress is discussed, particulary in slurry fuel preparation and particle size distribution.

  14. Using ground-based GPS to characterize atmospheric turbulence

    NASA Astrophysics Data System (ADS)

    Nilsson, T.; Davis, J. L.; Hill, E. M.

    2009-08-01

    A new method for measuring and studying atmospheric turbulence is presented. The method uses data from a local network of GPS receivers. The GPS data are processed in a way that assures that the estimated zenith total delays (ZTD) contain the effects of atmospheric turbulence present in the GPS observations. The turbulence is characterized using the spatial structure function for the atmospheric zenith total delay. The structure function is modeled by an expression with unknown parameters which contains information about the turbulence. The unknown parameters are solved by a fit to the observed ZTD variations. We apply the method to GPS data from the Yucca Mountain network, Nevada, USA. The results show that the magnitude of the turbulent variations in that region have a strong seasonal dependence, with much larger variations in summer compared to winter.

  15. Characterization of silicate based cathodes for Li Ion Batteries

    NASA Astrophysics Data System (ADS)

    Kumar, Ajay; Nazri, Gholam-Abbas; Nazri, Maryam; Nail, Vaman; Vaishnava, Prem; Naik, Ratna; Energy Group Collaboration; Energy Group Collaboration; Energy Group Collaboration

    2013-03-01

    The silicate compounds Li2MSiO4, where M = Mn, Fe, Co and Ni have gained interest as electrode materials for Lithium ion batteries due to their high theoretical capacity (>330mAh/g), high thermal stability due to strong Si-O covalent bonds, environmental friendliness, and low cost. However, these materials intrinsically have low electrical conductivity. To improve conductivity of these classes of electrode materials, we synthesized Li2MnSiO4 and Li2FeSiO4 by solid state reaction in an argon atmosphere. The lithium transition metal silicates were compounded with graphene nano-sheets and the composites were used as positive electrode in a coin cell configuration.. The materials structure-composition, morphology, conductivity and electrochemical performance were characterized by XRD, XPS, SEM, TEM and electrochemical techniques.The detail structure-composition analysis and electrochemical performance of the silicate electrodes will be reported.

  16. Performance and characterization of a new tannin-based coagulant

    NASA Astrophysics Data System (ADS)

    Beltrán-Heredia, J.; Sánchez-Martín, J.; Gómez-Muñoz, C.

    2012-09-01

    Diethanolamine and formaldehyde were employed to cationize tannins from black wattle. This novel coagulant called CDF was functionally characterized in removing sodium dodecylbenzene sulfonate (anionic surfactant) and Palatine Fast Black WAN (azoic dye). Refined tannin-derived commercial coagulants exhibited similar efficiency, while CDF presented higher coagulant ability than alum, a usual coagulant agent. Low doses of CDF (ca. 100 mg L-1) were able to remove more than 70 % of surfactant and more than 85 % of dye (initial pollutant concentration of ca. 100 mg L-1) and it presented no temperature affection and worked at a relatively wide pH range. Surfactant and dye removal responded to the classical coagulant-and-adsorption models, such as Frumkin-Fowler-Guggenheim or Gu and Zhu in the case of surfactant, and Langmuir and Freundlich in the case of dye.

  17. Characterization of hydrogen barrier coatings for titanium-base alloys

    NASA Astrophysics Data System (ADS)

    Leguey, T.; Baluc, N.; Jansen, F.; Victoria, M.

    2002-12-01

    The purpose of this study was to investigate the barrier efficiency of a thick thermal spray deposit on the α-titanium alloy, Ti-5Al-2.4Sn against hydrogen penetration. Therefore, a duplex coating has been applied by plasma spraying using a Sulzer Metco F4 gun. The selected duplex coating system consisted of a 0.1-0.2 mm thick tantalum bond layer and a chromium oxide top layer doped with 3 wt% titanium oxide. The achieved thickness of the top layer was about 0.6 mm. The coated specimens have been characterized with regard to bond strength, hardness and microstructure. Hydrogen charging experiments were performed in a Sievert's apparatus.

  18. Characterization of Silicon Photomultiplier based detectors with digital electronics

    NASA Astrophysics Data System (ADS)

    Daugherty, Hadyn; Taylor, Steven; Hasse, Adam; Grzywacz, Robert

    2014-09-01

    Due to their compact design and good timing performance Silicon Photomultipliers (SiPMT) were chosen to be used to readout the light from the plastic scintillator detector used as a trigger for the Versatile Array of Neutron Detectors at Low Energy (VANDLE). Prior to development of the new system, we have performed proof of principle studies, to demonstrate that the SiPMT, provided by Sensl is a viable replacement for the conventional photomultiplier. We have build a prototype detector, develop electronics readout chain and characterized its performance using the Digital Data Acquisition system at the University of Tennessee. This experience led to construction of segmented trigger detector which will be used in future VANDLE experiments. *This research was sponsored in part by the National Nuclear Security Administration under the Stewardship Science Academic Alliances program through DOE Cooperative Agreement No. DE-FG52-08NA28552 and the DOE Office of Nuclear Physics. Due to their compact design and good timing performance Silicon Photomultipliers (SiPMT) were chosen to be used to readout the light from the plastic scintillator detector used as a trigger for the Versatile Array of Neutron Detectors at Low Energy (VANDLE). Prior to development of the new system, we have performed proof of principle studies, to demonstrate that the SiPMT, provided by Sensl is a viable replacement for the conventional photomultiplier. We have build a prototype detector, develop electronics readout chain and characterized its performance using the Digital Data Acquisition system at the University of Tennessee. This experience led to construction of segmented trigger detector which will be used in future VANDLE experiments. *This research was sponsored in part by the National Nuclear Security Administration under the Stewardship Science Academic Alliances program through DOE Cooperative Agreement No. DE-FG52-08NA28552 and the DOE Office of Nuclear Physics. University of Tennessee

  19. Ear-canal acoustic admittance and reflectance measurements in human neonates. II. Predictions of middle-ear dysfunction and sensorineural hearing loss

    NASA Astrophysics Data System (ADS)

    Keefe, Douglas H.; Gorga, Michael P.; Neely, Stephen T.; Zhao, Fei; Vohr, Betty R.

    2003-01-01

    This report describes relationships between middle-ear measurements of acoustic admittance and energy reflectance (YR) and measurements of hearing status using visual reinforcement audiometry in a neonatal hearing-screening population. Analyses were performed on 2638 ears in which combined measurements were obtained [Norton et al., Ear Hear. 21, 348-356 (2000)]. The measurements included distortion-product otoacoustic emissions (DPOAE), transient evoked otoacoustic emissions (TEOAE), and auditory brainstem responses (ABR). Models to predict hearing status using DPOAEs, TEOAEs, or ABRs were each improved by the addition of the YR factors as interactions, in which factors were calculated using factor loadings from Keefe et al. [J. Acoust. Soc. Am. 113, 389-406 (2003)]. This result suggests that information on middle-ear status improves the ability to predict hearing status. The YR factors were used to construct a middle-ear dysfunction test on 1027 normal-hearing ears in which DPOAE and TEOAE responses were either both present or both absent, the latter condition being viewed as indicative of middle-ear dysfunction. The middle-ear dysfunction test classified these ears with a nonparametric area (A) under the relative operating characteristic curve of A=0.86, and classified normal-hearing ears that failed two-stage hearing-screening tests with areas A=0.84 for DPOAE/ABR, and A=0.81 for TEOAE/ABR tests. The middle-ear dysfunction test adequately generalized to a new sample population (A=0.82).

  20. A biodynamic feedthrough model based on neuromuscular principles.

    PubMed

    Venrooij, Joost; Abbink, David A; Mulder, Mark; van Paassen, Marinus M; Mulder, Max; van der Helm, Frans C T; Bulthoff, Heinrich H

    2014-07-01

    A biodynamic feedthrough (BDFT) model is proposed that describes how vehicle accelerations feed through the human body, causing involuntary limb motions and so involuntary control inputs. BDFT dynamics strongly depend on limb dynamics, which can vary between persons (between-subject variability), but also within one person over time, e.g., due to the control task performed (within-subject variability). The proposed BDFT model is based on physical neuromuscular principles and is derived from an established admittance model-describing limb dynamics-which was extended to include control device dynamics and account for acceleration effects. The resulting BDFT model serves primarily the purpose of increasing the understanding of the relationship between neuromuscular admittance and biodynamic feedthrough. An added advantage of the proposed model is that its parameters can be estimated using a two-stage approach, making the parameter estimation more robust, as the procedure is largely based on the well documented procedure required for the admittance model. To estimate the parameter values of the BDFT model, data are used from an experiment in which both neuromuscular admittance and biodynamic feedthrough are measured. The quality of the BDFT model is evaluated in the frequency and time domain. Results provide strong evidence that the BDFT model and the proposed method of parameter estimation put forward in this paper allows for accurate BDFT modeling across different subjects (accounting for between-subject variability) and across control tasks (accounting for within-subject variability). PMID:24043420

  1. Dithienylethene-based rotaxanes: synthesis, characterization and properties.

    PubMed

    Hu, Fang; Huang, Juanyun; Cao, Meijiao; Chen, Zhao; Yang, Ying-Wei; Liu, Sheng Hua; Yin, Jun

    2014-10-21

    The photochromic materials have been widely applied in many fields. In this article, we report a class of photochromic ammoniums with a dithienylethene backbone. They were utilized as templates to construct mechanically interlocked rotaxanes and pseudorotaxanes showing photo-responsive behavior by template-directed clipping reaction and the threading approach. The structures of novel rotaxanes were well defined. It is worth mentioning that the single crystal structure of [3]rotaxane containing two N-hetero crown ether units was obtained. Their photoisomerization behavior was investigated. These N-hetero crown ether-based rotaxanes displayed good reversibility and similar photochromic behaviors to their corresponding ammoniums when they underwent UV/vis photoirradiation. Interestingly, the cucurbit[6]uril-based pseudorotaxane showed better photoisomerization than its corresponding ammonium and those of N-hetero crown ether-based rotaxanes. PMID:25081736

  2. Preparation and characterization of some graphene based nanocomposite materials.

    PubMed

    Sheshmani, Shabnam; Amini, Raheleh

    2013-06-01

    In this study, graphene based sheets such as graphene oxide (GO) and graphene (G) were produced via a facile preparation route involving graphite oxidation, ultrasonic exfoliation and chemical reduction. Also, this paper reports simple approaches for deposition of manganese dioxide, ferric hydroxide and cobalt nanoparticles onto the surface of the graphene based sheets. Chemical deposition method of metal salt with graphene based sheets was performed to prepare nanocomposites. The structural, surface and characteristics of the GO, G and their nanocomposites were investigated by Fourier transform infrared spectroscopy, Raman spectroscopy, powder X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, atomic force microscopy and X-ray photoelectron spectroscopy. The results demonstrated that interaction between GO as matrix and metal nanoparticles were via hydroxyl, carbonyl and/or carboxylate groups. The metal nanoparticles were homogeneously distributed on the matrix of composite. PMID:23618279

  3. Underground object characterization based on neural networks for ground penetrating radar data

    NASA Astrophysics Data System (ADS)

    Zhang, Yu; Huston, Dryver; Xia, Tian

    2016-04-01

    In this paper, an object characterization method based on neural networks is developed for GPR subsurface imaging. Currently, most existing studies demonstrate detecting and imaging objects of cylindrical shapes. While in this paper, no restriction is imposed on the object shape. Three neural network algorithms are exploited to characterize different types of object signatures, including object shape, object material, object size, object depth and subsurface medium's dielectric constant. Feature extraction is performed to characterize the instantaneous amplitude and time delay of the reflection signal from the object. The characterization method is evaluated utilizing the data synthesized with the finite-difference timedomain (FDTD) simulator.

  4. SYNCHROTRON X-RAY BASED CHARACTERIZATION OF CDZNTE CRYSTALS

    SciTech Connect

    Duff, M

    2006-09-28

    Synthetic CdZnTe or 'CZT' crystals can be used for the room temperature-based detection of {gamma}-radiation. Structural/morphological heterogeneities within CZT, such as twinning, inclusions, and polycrystallinity can affect detector performance. We used a synchrotron-based X-ray technique, specifically extended X-ray absorption fine-structure (EXAFS) spectroscopy, to determine whether there are differences on a local structural level between intact CZT of high and low radiation detector performance. These studies were complemented by data on radiation detector performance and transmission IR imaging. The EXAFS studies revealed no detectable local structural differences between the two types of CZT materials.

  5. Combustion characterization of beneficiated coal-based fuels

    SciTech Connect

    Chow, O.K.; Nsakala, N.Y.

    1990-06-01

    The objectives of this project include: (1) the development of an engineering data base which will provide detailed information on the properties of BCFs influencing combustion, ash deposition, ash erosion, particulate collection, and missions; and (2) the application of this technical data base to predict the performance and economic impacts of firing the BCFs in various commercial boiler designs. The technical approach used to develop the technical data includes: bench-scale fuel property, combustion, and ash deposition tests; pilot-scale combustion and ash effects test; and full-scale combustion tests.

  6. Surface characterization based on optical phase shifting interferometry

    DOEpatents

    Mello, Michael , Rosakis; Ares J.

    2011-08-02

    Apparatus, techniques and systems for implementing an optical interferometer to measure surfaces, including mapping of instantaneous curvature or in-plane and out-of-plane displacement field gradients of a sample surface based on obtaining and processing four optical interferograms from a common optical reflected beam from the sample surface that are relatively separated in phase by .pi./2.

  7. MICROBIAL CHARACTERIZATION OF MANURE BASED PERMEABLE REACTIVE BARRIER

    EPA Science Inventory

    The implementation of permeable reactive barriers (PRB) provides a viable option for the remediation of contaminants of environmental significance such as dissolved metals (i.e., chromium), chlorinated solvents, and nitrate/ammonia. The designs of PRBs are usually based on the a...

  8. Microstructural Characterization of Co-Based ODS Alloys

    NASA Astrophysics Data System (ADS)

    Zhang, Lin; Qu, Xuanhui; He, Xinbo; Din, Rafi-ud; Liu, Hengsan; Qin, Mingli; Zhu, Hongmin

    2012-11-01

    Co-based ODS alloys, strengthened by nanosized oxide dispersion and γ' precipitates, are potential high-temperature structural materials. The characteristics of the mechanically alloyed powder and the microstructural evolution of the Co-based ODS alloys were investigated. The results revealed that mechanical alloying had induced the formation of supersaturated solid solution in immiscible Co-Al-W-based alloys, originating mainly from extensive grain boundary region, high dislocation density, and ample point defect. Chemical compositions of mechanically alloyed Co-Al-W-based ODS alloys easily deviate from the γ/γ' two-phase region, leading to the existence of Al x Co, Co3W, Co7W6, and W phases in addition to the γ and γ' phases. Nonuniform distribution of alloying elements brings about the differences in morphologies and sizes of γ' precipitates. Microstructural formation process is impelled by spinodal decomposition mode, and spinodal decomposition behavior has been accelerated in the fine-grained alloy because of the presence of short-circuited diffusion paths for atomic movement.

  9. Characterization of low thermal conductivity PAN-based carbon fibers

    NASA Technical Reports Server (NTRS)

    Katzman, Howard A.; Adams, P. M.; Le, T. D.; Hemminger, Carl S.

    1992-01-01

    The microstructure and surface chemistry of eight low thermal conductivity (LTC) PAN-based carbon fibers were determined and compared with PAN-based fibers heat treated to higher temperatures. Based on wide-angle x ray diffraction, the LTC PAN fibers all appear to have a similar turbostratic structure with large 002 d-spacings, small crystallite sizes, and moderate preferred orientation. Limited small-angle x ray scattering (SAXS) results indicate that, with the exception of LTC fibers made by BASF, the LTC fibers do not have well developed pores. Transmission electron microscopy shows that the texture of the two LTC PAN-based fibers studied (Amoco T350/23X and /25X) consists of multiple sets of parallel, wavy, bent layers that interweave with each other forming a complex three dimensional network oriented randomly around the fiber axis. X ray photoelectron spectroscopy (XPS) analysis finds correlations between heat treated temperatures and the surface composition chemistry of the carbon fiber samples.

  10. Lake Superior Phytoplankton Characterization from the 2006 Probability Based Survey

    EPA Science Inventory

    We conducted a late summer probability based survey of Lake Superior in 2006 which consisted of 52 sites stratified across 3 depth zones. As part of this effort, we collected composite phytoplankton samples from the epilimnion and the fluorescence maxima (Fmax) at 29 of the site...

  11. Characterization of Anatolian traditional quince cultivars, based on microsatellite markers.

    PubMed

    Yüksel, C; Mutaf, F; Demirtaş, İ; Öztürk, G; Pektaş, M; Ergül, A

    2013-01-01

    We conducted simple sequence repeat (SSR) analyses of 15 traditional quince (Cydonia oblonga) cultivars from Anatolian gene sources for molecular characterization and investigation of genetic relationships. Three pear and two apple cultivars were used as references for SSR locus data analysis and to determine allele profiles between species. Eight SSR loci that were developed from apple and pear were used, and a total of 44 alleles were found among quince cultivars. The CH01F02 locus was found to have the highest identification probability, while the CH04E03 locus had the lowest identification probability. Analysis of similarity ratios between quince cultivars showed that the lowest similarity ratio was 18% (Eşme-Bardacık ± k), while the highest similarity ratio was 87% (Bursa-Osmancık ± k and Osmancık ± k-Viranyadevi). In the phylogenetic dendrogram, Eşme quince showed separate branching from other quince cultivars, and no synonymous accessions were found. These results suggest that SSR markers from pear and apple could be used to determine genetic variation among quince cultivars. These findings can be used to guide future quince breeding and management studies. PMID:24301958

  12. Design and Characterization of a Fabric-Based Softness Display.

    PubMed

    Bianchi, Matteo; Serio, Alessandro

    2015-01-01

    To enable a realistic tactile interaction with remote or virtual objects, softness information represents a fundamental property to be rendered via haptic devices. What is challenging is to reduce the complexity of such an information as it arises from contact mechanics and to find suitable simplifications that can lead an effective development of softness displays. A possible approach is to surrogate detailed tactile cues with information on the rate of spread of the contact area between the object and the finger as the contact force increases, i.e. force/area relation. This paradigm is called contact area spread rate. In this paper we discuss how such a paradigm has inspired the design of a tactile device (hereinafter referred to as Fabric Yielding Display, FYD-2), which exploits the elasticity of a fabric to mimic different levels of stiffness, while the contact area on the finger indenting the fabric is measured. In this manner, the FYD-2 can be controlled to reproduce force-area characteristics. In this work, we describe the FYD-2 architecture and report a psychophysical characterization. FYD-2 is shown to be able to accurately reproduce force-area curves of typical objects and to enable a reliable softness discrimination in human users. PMID:25720018

  13. Reflectance characterization of tape-based plasma mirrors

    NASA Astrophysics Data System (ADS)

    Shaw, B. H.; Steinke, S.; van Tilborg, J.; Leemans, W. P.

    2016-06-01

    Specular reflections of relativistic laser pulses from an overdense plasma mirror (PM) were studied experimentally. The pointing stability of the PM and reflectance of the input laser were characterized. The solid material used for the PM was a VHS tape. This study was done for the magnetic and plastic sides of the VHS tape, and for input light of both s and p-polarizations. The laser pulse fluence was varied by changing the focus position relative to the tape surface, which changed the spot size at the tape. The pointing fluctuations of the reflected pulses caused by the PM were ≃1 mrad. A peak reflectance of 82% was obtained from the plastic surface of the VHS tape when focusing s-polarized light 4 mm from the tape surface (the wavefront quality was confirmed to be conserved). An analytic model was developed to understand the physics of the interaction for each tape material and polarization. Fitting of our model parameters to the experimental results allowed an estimate of the key plasma parameters such as plasma expansion velocity, ionization intensity, and fraction of absorbed laser energy.

  14. Characterization of the KID-Based Light Detectors of CALDER

    NASA Astrophysics Data System (ADS)

    Casali, N.; Bellini, F.; Cardani, L.; Castellano, M. G.; Colantoni, I.; Coppolecchia, A.; Cosmelli, C.; Cruciani, A.; D'Addabbo, A.; Di Domizio, S.; Martinez, M.; Tomei, C.; Vignati, M.

    2016-07-01

    The aim of the Cryogenic wide-Area Light Detectors with Excellent Resolution (CALDER) project is the development of light detectors with active area of 5 × 5 cm2 and noise energy resolution smaller than 20 eV RMS, implementing phonon-mediated kinetic inductance detectors. The detectors are developed to improve the background suppression in large-mass bolometric experiments such as CUORE, via the double read-out of the light and the heat released by particles interacting in the bolometers. In this work, we present the characterization of the first light detectors developed by CALDER. We describe the analysis tools to evaluate the resonator parameters (resonant frequency and quality factors) taking into account simultaneously all the resonance distortions introduced by the read-out chain (as the feed-line impedance and its mismatch) and by the power stored in the resonator itself. We detail the method for the selection of the optimal point for the detector operation (maximizing the signal-to-noise ratio). Finally, we present the response of the detector to optical pulses in the energy range of 0{-}30 keV.

  15. Synthesis and characterization of a chitosan based nanocomposite injectable hydrogel.

    PubMed

    Wang, Qianqian; Chen, Dajun

    2016-01-20

    The aim of the current study was to enhance the mechanical property of chitosan/β-glycerophosphate disodium salt (CS/GP) injectable hydrogels. A novel nanocomposite injectable hydrogel was prepared by introducing attapulgite (ATP) nano particles into the CS/GP hydrogels. The mechanical properties of the composite hydrogels with two different water contents were characterized by tensile test, the results shown that the tensile strength and elongation at break of composite hydrogels both increased obviously with increasing of ATP content. And, in our testing range, the maximum values of tensile strength and elongation at break were both more than 5 times larger than that of neat CS/GP hydrogel. We discussed this enhancement effect in detail by Scanning electron microscope observations (SEM) and Fourier transform infrared spectroscopy testing (FT-IR). The SEM images of composite hydrogels shown quite different from the neat CS/GP hydrogel, where the pores were more tightly and with some uniform and smaller holes dispersed on the wall. FT-IR test results revealed that the introduction of ATP increased the cross-link density because of the hydrogen bonds formation between ATP nanoparticles and CS molecules. Also, we studied the impact of ATP introduction on gelation speed through tracking the dynamic process of the sol-gel transition by means of rheological measurement, and the results shown that the reaction rate increased significantly with the increase of ATP concentration. PMID:26572466

  16. Characterization of the KID-Based Light Detectors of CALDER

    NASA Astrophysics Data System (ADS)

    Casali, N.; Bellini, F.; Cardani, L.; Castellano, M. G.; Colantoni, I.; Coppolecchia, A.; Cosmelli, C.; Cruciani, A.; D'Addabbo, A.; Di Domizio, S.; Martinez, M.; Tomei, C.; Vignati, M.

    2015-11-01

    The aim of the Cryogenic wide-Area Light Detectors with Excellent Resolution (CALDER) project is the development of light detectors with active area of 5 × 5 cm2 and noise energy resolution smaller than 20 eV RMS, implementing phonon-mediated kinetic inductance detectors. The detectors are developed to improve the background suppression in large-mass bolometric experiments such as CUORE, via the double read-out of the light and the heat released by particles interacting in the bolometers. In this work, we present the characterization of the first light detectors developed by CALDER. We describe the analysis tools to evaluate the resonator parameters (resonant frequency and quality factors) taking into account simultaneously all the resonance distortions introduced by the read-out chain (as the feed-line impedance and its mismatch) and by the power stored in the resonator itself. We detail the method for the selection of the optimal point for the detector operation (maximizing the signal-to-noise ratio). Finally, we present the response of the detector to optical pulses in the energy range of 0{-}30 keV.

  17. Characterization of a starch based desiccant wheel dehumidifier

    NASA Astrophysics Data System (ADS)

    Beery, Kyle Edward

    Starch, cellulose, and hemicellulose have an affinity for water, and adsorb water vapor from air. Materials made from combinations of these biobased sugar polymers also have been found to possess adsorptive properties. An interesting possible application of these starch-based adsorbents is the desiccant wheel dehumidifier. The desiccant wheel dehumidifier is used in conjunction with a standard air conditioning system. In this process, ambient air is passed through a stationary section while a wheel packed with desiccant rotates through that section. The desiccant adsorbs humidity (latent load) from the air, and the air conditioning system then cools the air (sensible load). Several starch based adsorbents were developed and tested for adsorptive capacity in a new high throughput screening system. The best formulations from the high throughput screening system, also taking into account economic considerations and structural integrity, were considered for use in the desiccant wheel dehumidifier. A suitable adsorbent was chosen and formulated into a matrix structure for the desiccant wheel system. A prototype desiccant wheel system was constructed and the performance was investigated under varying regeneration temperatures and rotation speeds. The results from the experiments showed that the starch based desiccant wheel dehumidification system does transfer moisture from the inlet process stream to the outlet regeneration stream. The DESSIM model was modified for the starch based adsorbent and compared to the experimental results. Also, the results when the wheel parameters were varied were compared to the predicted results from the model. The results given by the starch based desiccant wheel system show the desired proof of concept.

  18. Ecological risk characterization based on exposure to contaminants through the Rocky Mountain Arsenal aquatic food chains

    SciTech Connect

    Toll, J.E.; Cothern, K.A.; Pavlou, S.; Tate, D.J.; Armstrong, J.P.

    1994-12-31

    This paper describes ecological risk characterization methods and results for characterizing potential risk from exposure to bioaccumulative contaminants of concern (aldrin, dieldrin, endrin, DDT, DDE, and mercury) through the lake food chains at Rocky Mountain Arsenal (RMA). Aquatic risks were estimated for the bald eagle, great blue heron, shorebird, and water bird using a prey-tissue-concentration-based food web model. Methods for estimating missing tissue concentration data were developed on a case-by-case basis and will be described. A sediment-based food web model was also considered and the reasons for its rejection will be described. Generalizable insights from the aquatic ecological risk characterization will be discussed.

  19. Performance characterization of structured light-based fingerprint scanner

    NASA Astrophysics Data System (ADS)

    Hassebrook, Laurence G.; Wang, Minghao; Daley, Raymond C.

    2013-05-01

    Our group believes that the evolution of fingerprint capture technology is in transition to include 3-D non-contact fingerprint capture. More specifically we believe that systems based on structured light illumination provide the highest level of depth measurement accuracy. However, for these new technologies to be fully accepted by the biometric community, they must be compliant with federal standards of performance. At present these standards do not exist for this new biometric technology. We propose and define a set of test procedures to be used to verify compliance with the Federal Bureau of Investigation's image quality specification for Personal Identity Verification single fingerprint capture devices. The proposed test procedures include: geometric accuracy, lateral resolution based on intensity or depth, gray level uniformity and flattened fingerprint image quality. Several 2-D contact analogies, performance tradeoffs and optimization dilemmas are evaluated and proposed solutions are presented.

  20. Antenna design and characterization based on the elementary antenna concept

    NASA Astrophysics Data System (ADS)

    Ligthart, L. P.

    An antenna-design technique based on an elementary-antenna model (an infinitesimal pillbox structure carrying electric and magnetic currents and containing propagating TEM fields) is developed and demonstrated. An EM description of a waveguide aperture is obtained by applying approximate boundary conditions at specific points; the transmitted field is developed locally into a set of TEM field components to compute the radiation pattern; and aperture matching is achieved by calculating the aperture reflection as well. Parallel-plate, circular, and rectangular waveguides; two single-polarization TEM waveguide radiators (with and without dielectric filling); a dielectric-filled dual-polarization TE(01) waveguide radiator; and a hybrid reflector array with limited beam switching based on the TE(01) radiator are presented.

  1. Transuranic contaminated waste form characterization and data base

    SciTech Connect

    McArthur, W.C.; Kniazewycz, B.G.

    1980-07-01

    This report outlines the sources, quantities, characteristics and treatment of transuranic wastes in the United States. This document serves as part of the data base necessary to complete preparation and initiate implementation of transuranic wastes, waste forms, waste container and packaging standards and criteria suitable for inclusion in the present NRC waste management program. No attempt is made to evaluate or analyze the suitability of one technology over another. Indeed, by the nature of this report, there is little critical evaluation or analysis of technologies because such analysis is only appropriate when evaluating a particular application or transuranic waste streams. Due to fiscal restriction, the data base is developed from a myriad of technical sources and does not necessarily contain operating experience and the current status of all technologies. Such an effort was beyond the scope of this report.

  2. Thermodynamic characterization of a diamond-based electron emitter

    NASA Astrophysics Data System (ADS)

    Fisher, T. S.; Strauss, A. M.; Davidson, J. L.; Kang, W. P.

    2000-01-01

    This paper contains a thermodynamic analysis of electron emission from a micro-fabricated diamond tip array. The analysis is based on experimental measurements of the current-voltage characteristics of an actual device. Field enhancement, applied field, and electrical current density are shown to influence thermodynamic performance. The idealized thermodynamic analysis predicts cooling rates above 10 W/cm2 for an existing device under room temperature operation and that 100 W/cm2 may be possible for future devices. .

  3. Design and Characterization of Styrene-Based Proton Exchange Membranes

    NASA Astrophysics Data System (ADS)

    Ebrasu, D.; Petreanu, I.; Patularu, L.; Stefanescu, I.; Valeanu, M.

    This paper deals with preparation of PEM, based on commercial block copolymer of the styrene-butadiene. The copolymer was structurally changed by sulfonation followed by cross linking, in order to design a Proton Exchange Membrane for Fuel Cells. The membranes were structural tested by FTIR Spectroscopy and Scanning Electron Microscopy. Ionic Exchange Capacity (IEC) and thermal behavior by Differential Scanning Calorimetry (DSC) were measured too.

  4. Interface characterization using an SEM-based micro-indentor

    SciTech Connect

    Lewis, M.H.; Cain, M.G.; Daniel, A.M.

    1995-10-01

    The design and performance of an SEM-based microindentor, for interfacial property measurements in CMCs, is described. It enables high resolution imaging and simultaneous load/displacement monitoring with capacity and resolution of 20 N {+-} 1 mN (load) and 100 {mu}m {+-} 10 nm (displacement). Its application to measurement of interface debond and shear stresses for a wide range of fibers and monofilaments is described.

  5. Development and Characterization of Colloidal Nanoparticle Based Photodetectors

    NASA Astrophysics Data System (ADS)

    Qin, Liqiao

    Colloidal nanoparticles have great potential in making high performance photodetectors as 1) their high surface area to volume ratio contributes to better absorption of light than bulk material does, 2) their 3-D quantum confinement effects enable continuous tuning of the detection wavelengths by changing the size of nanoparticles, 3) their high quantum efficiency benefits optical to electrical signal conversion, 4) their solution-based synthesis is well compatible with additional surface coating processes to improve the materials' performance, and 5) they are independent of the substrate onto which they are ultimately deposited, eliminating the lattice matching requirements inherent in the growth of crystalline semiconductors. In this thesis, high performance, large area, visible blind and wavelength selective planar/vertical/heterojunction organic and inorganic hybrid UV photodetectors based on polyvinyl-alcohol (PVA) coated ZnO colloidal nanoparticles created by top-down wet-chemical etching method onto different functional substrates for different applications were studied for the first time. With PVA surface passivation, suppressed parasitic green photoluminescence and enhanced UV emission of ZnO colloidal nanoparticles were achieved, which contributed to the high performance of the frbricated photodetectors. The planar PVA coated ZnO nanoparticles MSM photodetector with finger contacts fabricating by normal lithography and wet-etching method was done for the first time. The MSM photodetector has the highest normalized detectivity and response speed product compared with other reported photodetectors based on ZnO nanomaterials till the time of writing this thesis. Lowpass and wavelength selective bandpass alternative spectral response of photoconductor and p-GaN/ZnO heterojunction photodiode were achieved relying on illuminating directions through GaN or ZnO. Reproducibility, distribution uniformity, sensitivity dependence of substrates, and aging effect of

  6. Synthesis, characterization, biological and electrochemical evaluation of novel ether based ON donor bidentate Schiff bases

    NASA Astrophysics Data System (ADS)

    Shabbir, Muhammad; Akhter, Zareen; Ahmad, Iqbal; Ahmed, Safeer; Ismail, Hammad; Mirza, Bushra; McKee, Vickie; Bolte, Michael

    2016-07-01

    Four novel ON donor Schiff bases (E)-2-((4-phenoxyphenylimino)methyl)phenol (HL1), (E)-2-((4-(4-biphenyloxy)phenylimino)methyl)phenol(HL2), (E)-2-((4-(naphthalen-1-yloxy) phenylimino)methyl)phenol(HL3)and(E)-2-((4-(2-naphthoxy)phenylimino)methyl)phenol (HL4)have been synthesized and characterized by various spectroscopic, analytical and electro-analytical techniques. Single crystal X-ray diffraction analysis of Schiff base (HL3) revealed that phenol and anthracene rings are inclined at 30.25(9)° and 89.64(4)° to the central phenyl ring, respectively. Intra and inter molecular interactions are observed in single crystal analysis of HL3 Intramolecular interactions are hydrogen bonding but most of the intermolecular interactions are of the C-H … π type. There is a bit of π … π stacking between the anthracene groups. Only compounds (HL1) and (HL3) have been investigated for the biological activities due to slight solubility of (HL2) and (HL4) in DMSO. The results of brine shrimp cytotoxicity assay indicated LD50 values <1 μg/ml showing significant antitumor activity with IC50 values 14.20 and 4.54 μg/ml respectively. The compounds were highly active in protecting DNA against hydroxyl free radicals in concentration dependent manner. Voltammetric results indicated that one electron irreversible oxidation product is formed due to hydroxyl moiety and the process is diffusion controlled. On exposing to DNA environment the electrooxidised product developed electrostatic linkage and groove binding intercalation while consuming the DNA concentration substantially. The binding strength was quantitative in terms of drug-DNA binding of the order of 104 M-1.

  7. Synthesis, characterization, biological and electrochemical evaluation of novel ether based ON donor bidentate Schiff bases

    NASA Astrophysics Data System (ADS)

    Shabbir, Muhammad; Akhter, Zareen; Ahmad, Iqbal; Ahmed, Safeer; Ismail, Hammad; Mirza, Bushra; McKee, Vickie; Bolte, Michael

    2016-07-01

    Four novel ON donor Schiff bases (E)-2-((4-phenoxyphenylimino)methyl)phenol (HL1), (E)-2-((4-(4-biphenyloxy)phenylimino)methyl)phenol(HL2), (E)-2-((4-(naphthalen-1-yloxy) phenylimino)methyl)phenol(HL3)and(E)-2-((4-(2-naphthoxy)phenylimino)methyl)phenol (HL4)have been synthesized and characterized by various spectroscopic, analytical and electro-analytical techniques. Single crystal X-ray diffraction analysis of Schiff base (HL3) revealed that phenol and anthracene rings are inclined at 30.25(9)° and 89.64(4)° to the central phenyl ring, respectively. Intra and inter molecular interactions are observed in single crystal analysis of HL3 Intramolecular interactions are hydrogen bonding but most of the intermolecular interactions are of the C-H … π type. There is a bit of π … π stacking between the anthracene groups. Only compounds (HL1) and (HL3) have been investigated for the biological activities due to slight solubility of (HL2) and (HL4) in DMSO. The results of brine shrimp cytotoxicity assay indicated LD50 values <1 μg/ml showing significant antitumor activity with IC50 values 14.20 and 4.54 μg/ml respectively. The compounds were highly active in protecting DNA against hydroxyl free radicals in concentration dependent manner. Voltammetric results indicated that one electron irreversible oxidation product is formed due to hydroxyl moiety and the process is diffusion controlled. On exposing to DNA environment the electrooxidised product developed electrostatic linkage and groove binding intercalation while consuming the DNA concentration substantially. The binding strength was quantitative in terms of drug-DNA binding of the order of 104 M-1.

  8. Mn-based nanostructured building blocks: Synthesis, characterization and applications

    NASA Astrophysics Data System (ADS)

    Beltran Huarac, Juan

    The quest for smaller functional elements of devices has stimulated increased interest in charge-transfer phenomena at the nanoscale. Mn-based nanostructured building blocks are particularly appealing given that the excited states of high-spin Mn2+ ions induce unusual d-d energy transfer processes, which is critical for better understanding the performance of electronic and spintronic devices. These nanostructures also exhibit unique properties superior to those of common Fe- and Co-based nanomaterials, including: excellent structural flexibility, enhanced electrochemical energy storage, effective ion-exchange dynamics, more comprehensive transport mechanisms, strong quantum yield, and they act as effective luminescent centers for more efficient visible light emitters. Moreover, Mn-based nanostructures (MBNs) are crucial for the design and assembly of inexpensive nanodevices in diluted magnetic semiconductors (DMS), optoelectronics, magneto-optics, and field-effect transistors, owing to the great abundance and low-cost of Mn. Nonetheless, the paucity of original methods and techniques to fabricate new multifunctional MBNs that fulfill industrial demands limits the sustainable development of innovative technology in materials sciences. In order to meet this critical need, in this thesis we develop and implement novel methods and techniques to fabricate zero- and one-dimensional highly-crystalline new-generation MBNs conducive to the generation of new technology, and provide alternative and feasible miniaturization strategies to control and devise at nanometric precision their size, shape, structure and composition. Herein, we also establish the experimental conditions to grow Mn-based nanowires (NWs), nanotubes (NTs), nanoribbons (NRs), nanosaws (NSs), nanoparticles (NPs) and nanocomposites (NCs) via chemical/physical deposition and co-precipitation chemical routes, and determine the pertinent arrangements to our experimental schemes in order to extend our bottom

  9. Electron microscopy characterization of Li-based cathode materials for battery applications

    NASA Astrophysics Data System (ADS)

    Phillips, Patrick; Klie, Robert

    2014-03-01

    The role of aberration-corrected scanning transmission electron microscopy (STEM) in materials characterization is examined with respect to Li-based cathode materials for battery applications. STEM-based methods are quickly becoming the most promising characterization tools for these materials, owed largely to the wide-range of techniques available on advanced STEM instruments, including the direct imaging of both heavy and light elements, and both energy-dispersive X-ray (EDX) and electron energy loss (EEL) spectroscopies. The current talk with focus on structural and chemical characterization of a Li-based cathode material, both in a pristine and irradiated state. Focus will remain on the nucleation of structural transitions, while also characterizing relevant parameters such as the manganese valence and oxygen presence. Various imaging modes, including high/low angle annular dark field (H/LAADF) and annular bright field (ABF), in conjunction with EELS, will be used extensively for this analysis.

  10. Design and characterization of integrated-optic-based chemical sensors

    NASA Astrophysics Data System (ADS)

    Beregovskii, Iouri

    A novel line of integrated-optic-based chemical sensors was developed. The sensors are based on modification of the optical cavity of a single-mode semiconductor distributed Bragg reflector (DBR) laser. A sensitive layer changes its refractive index in presence of a specific chemical, thus changing the effective refractive index of the section and the optical length of the cavity. This results in laser frequency shift measured either directly or by heterodyne detection using a reference laser as the second source. It is shown that DBR-laser-based sensors can achieve in principle a much higher sensitivity than passive sensors, such as Mach- Zehnder interferometers, due to the narrow linewidth of DBR lasers. The theory of DBR-laser-based sensors is described. It allows optimizing the sensitive section length and field confinement in the sensitive layer for the lowest detection limit. The optimum parameters depend on cavity losses and absorption of the sensitive material. Numerical modeling shows a wide acceptable range of sensitive section parameters for low-loss materials, while for higher-loss materials this range becomes much narrower. Narrow-linewidth DBR lasers are required for high sensitivity. In this respect, sol-gel waveguides with and without Bragg grating were incorporated in the DBR laser scheme. Single-mode operation of DBR lasers with sol-gel waveguide gratings was demonstrated for the first time, with 34-dB side mode suppression and a short-term linewidth of 150 to 500 kHz. A 3-section configuration with sol-gel waveguides and fiber grating showed 28-dB side mode suppression and a short-term linewidth of 600 kHz. Chemical sensing was performed with fiber grating, sol- gel waveguide grating, and 3-section DBR lasers. The first two types showed frequency shift of over 130 MHz in the presence of acetone vapors, and reversibility within experimental errors. The 3-section scheme showed significant dispersion of response and lack of reversibility due to