WorldWideScience

Sample records for surface specific vibrational

  1. PREFACE: Vibrations at surfaces Vibrations at surfaces

    Science.gov (United States)

    Rahman, Talat S.

    2011-12-01

    This special issue is dedicated to the phenomenon of vibrations at surfaces—a topic that was indispensible a couple of decades ago, since it was one of the few phenomena capable of revealing the nature of binding at solid surfaces. For clean surfaces, the frequencies of modes with characteristic displacement patterns revealed how surface geometry, as well as the nature of binding between atoms in the surface layers, could be different from that in the bulk solid. Dispersion of the surface phonons provided further measures of interatomic interactions. For chemisorbed molecules on surfaces, frequencies and dispersion of the vibrational modes were also critical for determining adsorption sites. In other words, vibrations at surfaces served as a reliable means of extracting information about surface structure, chemisorption and overlayer formation. Experimental techniques, such as electron energy loss spectroscopy and helium-atom-surface scattering, coupled with infra-red spectroscopy, were continually refined and their resolutions enhanced to capture subtleties in the dynamics of atoms and molecules at surfaces. Theoretical methods, whether based on empirical and semi-empirical interatomic potential or on ab initio electronic structure calculations, helped decipher experimental observations and provide deeper insights into the nature of the bond between atoms and molecules in regions of reduced symmetry, as encountered on solid surfaces. Vibrations at surfaces were thus an integral part of the set of phenomena that characterized surface science. Dedicated workshops and conferences were held to explore the variety of interesting and puzzling features revealed in experimental and theoretical investigations of surface vibrational modes and their dispersion. One such conference, Vibrations at Surfaces, first organized by Harald Ibach in Juelich in 1980, continues to this day. The 13th International Conference on Vibrations at Surfaces was held at the University of

  2. Vibrational states on Pd surfaces

    Science.gov (United States)

    Sklyadneva, I. Yu.; Rusina, G. G.; Chulkov, E. V.

    1997-04-01

    We present the calculation of vibrational modes and lattice relaxation for the Pd(100), (110) and (111) surfaces. The surface phonon frequencies and polarizations are obtained using embedded-atom potentials. Comparison of the calculated frequency values with available experimental data gives agreement within 0.2 THz.

  3. Vibrations on Al surfaces covered by sodium

    Science.gov (United States)

    Rusina, G. G.; Eremeev, S. V.; Borisova, S. D.; Sklyadneva, I. Yu.; Chulkov, E. V.

    2006-09-01

    In this paper we present the results of a comparative study of vibrational and structural properties of the ordered (√{3}×√{3})R30∘ and c(2 × 2) phases formed by Na adatoms at room temperature on the Al(1 1 1) and Al(1 0 0) surfaces, respectively. The surface relaxation, surface phonon dispersion, and polarization of vibrational modes are calculated using the embedded-atom method. Our calculated structural parameters are in agreement with experimental and ab initio results. The obtained vibrational frequencies compare fairly well with available experimental data.

  4. Surface acoustic wave (SAW) vibration sensors.

    Science.gov (United States)

    Filipiak, Jerzy; Solarz, Lech; Steczko, Grzegorz

    2011-01-01

    In the paper a feasibility study on the use of surface acoustic wave (SAW) vibration sensors for electronic warning systems is presented. The system is assembled from concatenated SAW vibration sensors based on a SAW delay line manufactured on a surface of a piezoelectric plate. Vibrations of the plate are transformed into electric signals that allow identification of the sensor and localization of a threat. The theoretical study of sensor vibrations leads us to the simple isotropic model with one degree of freedom. This model allowed an explicit description of the sensor plate movement and identification of the vibrating sensor. Analysis of frequency response of the ST-cut quartz sensor plate and a damping speed of its impulse response has been conducted. The analysis above was the basis to determine the ranges of parameters for vibrating plates to be useful in electronic warning systems. Generally, operation of electronic warning systems with SAW vibration sensors is based on the analysis of signal phase changes at the working frequency of delay line after being transmitted via two circuits of concatenated four-terminal networks. Frequencies of phase changes are equal to resonance frequencies of vibrating plates of sensors. The amplitude of these phase changes is proportional to the amplitude of vibrations of a sensor plate. Both pieces of information may be sent and recorded jointly by a simple electrical unit.

  5. Surface Acoustic Wave (SAW Vibration Sensors

    Directory of Open Access Journals (Sweden)

    Jerzy Filipiak

    2011-12-01

    Full Text Available In the paper a feasibility study on the use of surface acoustic wave (SAW vibration sensors for electronic warning systems is presented. The system is assembled from concatenated SAW vibration sensors based on a SAW delay line manufactured on a surface of a piezoelectric plate. Vibrations of the plate are transformed into electric signals that allow identification of the sensor and localization of a threat. The theoretical study of sensor vibrations leads us to the simple isotropic model with one degree of freedom. This model allowed an explicit description of the sensor plate movement and identification of the vibrating sensor. Analysis of frequency response of the ST-cut quartz sensor plate and a damping speed of its impulse response has been conducted. The analysis above was the basis to determine the ranges of parameters for vibrating plates to be useful in electronic warning systems. Generally, operation of electronic warning systems with SAW vibration sensors is based on the analysis of signal phase changes at the working frequency of delay line after being transmitted via two circuits of concatenated four-terminal networks. Frequencies of phase changes are equal to resonance frequencies of vibrating plates of sensors. The amplitude of these phase changes is proportional to the amplitude of vibrations of a sensor plate. Both pieces of information may be sent and recorded jointly by a simple electrical unit.

  6. Drops on hydrophobic surfaces & vibrated fluid surfaces

    DEFF Research Database (Denmark)

    Wind-Willassen, Øistein

    , and contribute this to preferred eigenmodes of the droplet oscillation. The second part of this thesis deals with a droplet bouncing on a vertically vibrated fluid bath of the same liquid, a system which is the first known macroscopic example of pilot-wave dynamics. An introduction to the experimental set...

  7. Localized Surface Plasmons in Vibrating Graphene Nanodisks

    DEFF Research Database (Denmark)

    Wang, Weihua; Li, Bo-Hong; Stassen, Erik

    2016-01-01

    in graphene disks have the additional benefit to be highly tunable via electrical stimulation. Mechanical vibrations create structural deformations in ways where the excitation of localized surface plasmons can be strongly modulated. We show that the spectral shift in such a scenario is determined...... by a complex interplay between the symmetry and shape of the modal vibrations and the plasmonic mode pattern. Tuning confined modes of light in graphene via acoustic excitations, paves new avenues in shaping the sensitivity of plasmonic detectors, and in the enhancement of the interaction with optical emitters...

  8. Calculating vibrational spectra using modified Shepard interpolated potential energy surfaces.

    Science.gov (United States)

    Evenhuis, Christian R; Manthe, Uwe

    2008-07-14

    A potential energy interpolation approach based on modified Shepard interpolation and specifically designed for calculation of vibrational states is presented. The importance of the choice of coordinates for the rate of convergence is demonstrated. Studying the vibrational states of the water molecule as a test case, a coordinate system comprised of inverse bond distances and trigonometric functions of the bond angle is found to be particularly efficient. Different sampling schemes used to locate the reference points in the modified Shepard interpolation are investigated. A final scheme is recommended, which allows the construction of potential energy surfaces to sub-wave-number accuracy.

  9. Localized Surface Plasmons in Vibrating Graphene Nanodisks

    CERN Document Server

    Wang, Weihua; Mortensen, N Asger; Christensen, Johan

    2015-01-01

    Localized surface plasmons are confined collective oscillations of electrons in metallic nanoparticles. When driven by light, the optical response is dictated by geometrical parameters and the dielectric environment and plasmons are therefore extremely important for sensing applications. Plasmons in graphene disks have the additional benefit to be highly tunable via electrical stimulation. Mechanical vibrations create structural deformations in ways where the excitation of localized surface plasmons can be strongly modulated. We show that the spectral shift in such a scenario is determined by a complex interplay between the symmetry and shape of the modal vibrations and the plasmonic mode pattern. Tuning confined modes of light in graphene via acoustic excitations, paves new avenues in shaping the sensitivity of plasmonic detectors, and in the enhancement of the interaction with optical emitters, such as molecules, for future nanophotonic devices.

  10. New developments in IR surface vibrational spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Hirschmugl, C.J.; Lamont, C.L.A.; Williams, G.P. [Brookhaven National Lab., Upton, NY (United States). National Synchrotron Light Source

    1995-12-31

    Low frequency dynamics at surfaces, particularly in the region of the adsorbate-substrate vibrational modes is of fundamental importance in areas as varied as sliding friction, catalysis, corrosion and epitaxial growth. This paper reviews the new developments in low frequency Infrared Reflection Absorption Spectroscopy using synchrotron radiation as the source. Absolute changes induced in the far infrared for several adsorbate systems on Cu, including CO and H, are dominated by broadband reflectance changes and dipole forbidden vibrational modes which in some cases are an order of magnitude stronger than the dipole allowed modes. The experimental data can be explained by a theory developed by Persson, in which the dielectric response of the substrate is seen as playing a crucial role in the dynamics. In particular the relationships between the wavelength of the light, the penetration depth and the electron mean-free path, are critical.

  11. Microwave absorption by nanoresonator vibrations tuned with surface modification

    Science.gov (United States)

    Krivosudský, Ondrej; Cifra, Michal

    2016-08-01

    Elucidating the physical and chemical parameters that govern viscous damping of nanoresonator vibrations and their coupling to electromagnetic radiation is important for understanding the behavior of matter at the nanoscale. Here we develop an analytical model of microwave absorption of a longitudinally oscillating and electrically polar rod-like nanoresonator embedded in a viscoelastic fluid. We show that the slip length, which can be tuned via surface modifications, controls the quality factor and coupling of nanoresonator vibration modes to microwave radiation. We demonstrate that the larger slip length brings the sharper frequency response of the nanoresonator vibration and electromagnetic absorption. Our findings contribute to design guidelines of fluid embedded nanoresonator devices.

  12. Selective excitation of adsorbate vibrations on dissipative surfaces

    OpenAIRE

    2008-01-01

    The selective infrared (IR) excitation of molecular vibrations is a powerful tool to control the photoreactivity prior to electronic excitation in the ultraviolet / visible (UV/Vis) light regime ("vibrationally mediated chemistry"). For adsorbates on surfaces it has been theoretically predicted that IR preexcitation will lead to higher UV/Vis photodesorption yields and larger cross sections for other photoreactions. In a recent experiment, IR-mediated desorption of molecular hydrogen from a S...

  13. Measurement of dynamic surface tension by mechanically vibrated sessile droplets

    Science.gov (United States)

    Iwata, Shuichi; Yamauchi, Satoko; Yoshitake, Yumiko; Nagumo, Ryo; Mori, Hideki; Kajiya, Tadashi

    2016-04-01

    We developed a novel method for measuring the dynamic surface tension of liquids using mechanically vibrated sessile droplets. Under continuous mechanical vibration, the shape of the deformed droplet was fitted by numerical analysis, taking into account the force balance at the drop surface and the momentum equation. The surface tension was determined by optimizing four parameters: the surface tension, the droplet's height, the radius of the droplet-substrate contact area, and the horizontal symmetrical position of the droplet. The accuracy and repeatability of the proposed method were confirmed using drops of distilled water as well as viscous aqueous glycerol solutions. The vibration frequency had no influence on surface tension in the case of pure liquids. However, for water-soluble surfactant solutions, the dynamic surface tension gradually increased with vibration frequency, which was particularly notable for low surfactant concentrations slightly below the critical micelle concentration. This frequency dependence resulted from the competition of two mechanisms at the drop surface: local surface deformation and surfactant transport towards the newly generated surface.

  14. Vibrations on Cu surfaces covered with Ni monolayer

    Science.gov (United States)

    Sklyadneva, I. Yu.; Rusina, G. G.; Chulkov, E. V.

    1999-08-01

    Vibrational modes on the Cu(100) and Cu(111) surfaces covered with a Ni monolayer have been calculated using the embedded-atom method. A detailed discussion of the dispersion relations and polarizations of adsorbate modes and surface phonons is presented. The dispersion of the Rayleigh phonon is in good agreement with the experimental EELS data. The changes in interatomic force constants are discussed.

  15. Mitigating ground vibration by periodic inclusions and surface structures

    DEFF Research Database (Denmark)

    Andersen, Lars Vabbersgaard; Bucinskas, Paulius; Persson, Peter

    2016-01-01

    -dimensional finite-element model. The laboratory model employs soaked mattress foam placed within a box to mimic a finite volume of soil. The dynamic properties of the soaked foam ensure wavelengths representative of ground vibration in small scale. Comparison of the results from the two models leads......Ground vibration from traffic is a source of nuisance in urbanized areas. Trenches and wave barriers can provide mitigation of vibrations, but single barriers need to have a large depth to be effective-especially in the low-frequency range relevant to traffic-induced vibration. Alternatively...... well-defined behavior can be expected for transient loads and finite structures. However, some mitigation may occur. The paper aims at quantifying the mitigation effect of nearly periodic masses placed on the ground surface using two approaches: a small-scale laboratory model and a three...

  16. Surface enhanced vibrational spectroscopy for the detection of explosives

    Science.gov (United States)

    Büttner, Fritjof; Hagemann, Jan; Wellhausen, Mike; Funke, Sebastian; Lenth, Christoph; Rotter, Frank; Gundrum, Lars; Plachetka, Ulrich; Moormann, Christian; Strube, Moritz; Walte, Andreas; Wackerbarth, Hainer

    2013-10-01

    A detector which can detect a broad range of explosives without false alarms is urgently needed. Vibrational spectroscopy provides specific spectral information about molecules enabling the identification of analytes by their "fingerprint" spectra. The low detection limit caused by the inherent weak Raman process can be increased by the Surface Enhanced Raman (SER) effect. This is particularly attractive because it combines low detection limits with high information content for establishing molecular identity. Based on SER spectroscopy we have constructed a modular detection system. Here, we want to show a combination of SER spectroscopy and chemometrics to distinguish between chemically similar substances. Such an approach will finally reduce the false alarm rate. It is still a challenge to determine the limit of detection of the analyte on a SER substrate or its enhancement factor. For physisorbed molecules we have applied a novel approach. By this approach the performance of plasmonic substrates and Surface Enhanced Raman Scattering (SERS) enhancement of explosives can be evaluated. Moreover, novel nanostructured substrates for surface enhanced IR absorption (SEIRA) spectroscopy will be presented. The enhancement factor and a limit of detection are estimated.

  17. Vibrations of alkali metal overlayers on metal surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Rusina, G G; Eremeev, S V; Borisova, S D [Institute of Strength Physics and Materials Science SB RAS, 634021, Tomsk (Russian Federation); Echenique, P M; Chulkov, E V [Donostia International Physics Center (DIPC), 20018 San Sebastian/Donostia, Basque Country (Spain); Benedek, G [Dipartimento di Scienza dei Materiali, Universita di Milano-Bicocca, Via Cozzi 53, 20125 Milano (Italy)], E-mail: rusina@ispms.tsc.ru

    2008-06-04

    We review the current progress in the understanding of vibrations of alkalis adsorbed on metal surfaces. The analysis of alkali vibrations was made on the basis of available theoretical and experimental results. We also include in this discussion our recent calculations of vibrations in K/Pt(111) and Li(Na)/Cu(001) systems. The dependence of alkali adlayer localized modes on atomic mass, adsorption position and coverage as well as the dependence of vertical vibration frequency on the substrate orientation is discussed. The square root of atomic mass dependence of the vertical vibration energy has been confirmed by using computational data for alkalis on the Al(111) and Cu(001) substrates. We have confirmed that in a wide range of submonolayer coverages the stretch mode energy remains nearly constant while the energy of in-plane polarized modes increases with the increase of alkali coverage. It was shown that the spectrum of both stretch and in-plane vibrations can be very sensitive to the adsorption position of alkali atoms and substrate orientation.

  18. Vibrations of alkali metal overlayers on metal surfaces

    Science.gov (United States)

    Rusina, G. G.; Eremeev, S. V.; Echenique, P. M.; Benedek, G.; Borisova, S. D.; Chulkov, E. V.

    2008-06-01

    We review the current progress in the understanding of vibrations of alkalis adsorbed on metal surfaces. The analysis of alkali vibrations was made on the basis of available theoretical and experimental results. We also include in this discussion our recent calculations of vibrations in K/Pt(111) and Li(Na)/Cu(001) systems. The dependence of alkali adlayer localized modes on atomic mass, adsorption position and coverage as well as the dependence of vertical vibration frequency on the substrate orientation is discussed. The square root of atomic mass dependence of the vertical vibration energy has been confirmed by using computational data for alkalis on the Al(111) and Cu(001) substrates. We have confirmed that in a wide range of submonolayer coverages the stretch mode energy remains nearly constant while the energy of in-plane polarized modes increases with the increase of alkali coverage. It was shown that the spectrum of both stretch and in-plane vibrations can be very sensitive to the adsorption position of alkali atoms and substrate orientation.

  19. Effect of fingerprints orientation on skin vibrations during tactile exploration of textured surfaces

    CERN Document Server

    Prevost, Alexis; Debrégeas, Georges

    2009-01-01

    In humans, the tactile perception of fine textures is mediated by skin vibrations when scanning the surface with the fingertip. These vibrations are encoded by specific mechanoreceptors, Pacinian corpuscules (PCs), located about 2 mm below the skin surface. In a recent article, we performed experiments using a biomimetic sensor which suggest that fingerprints (epidermal ridges) may play an important role in shaping the subcutaneous stress vibrations in a way which facilitates their processing by the PC channel. Here we further test this hypothesis by directly recording the modulations of the fingerpad/substrate friction force induced by scanning an actual fingertip across a textured surface. When the fingerprints are oriented perpendicular to the scanning direction, the spectrum of these modulations shows a pronounced maximum around the frequency v/lambda, where v is the scanning velocity and lambda the fingerprints period. This simple biomechanical result confirms the relevance of our previous finding for hu...

  20. Effect of fingerprints orientation on skin vibrations during tactile exploration of textured surfaces.

    Science.gov (United States)

    Prevost, Alexis; Scheibert, Julien; Debrégeas, Georges

    2009-09-01

    In humans, the tactile perception of fine textures is mediated by skin vibrations when scanning the surface with the fingertip. These vibrations are encoded by specific mechanoreceptors, Pacinian corpuscules (PCs), located about 2 mm below the skin surface. In a recent article, we performed experiments using a biomimetic sensor which suggest that fingerprints (epidermal ridges) may play an important role in shaping the subcutaneous stress vibrations in a way which facilitates their processing by the PC channel. Here we further test this hypothesis by directly recording the modulations of the fingerpad/substrate friction force induced by scanning an actual fingertip across a textured surface. When the fingerprints are oriented perpendicular to the scanning direction, the spectrum of these modulations shows a pronounced maximum around the frequency v/lambda, where v is the scanning velocity and lambda the fingerprints period. This simple biomechanical result confirms the relevance of our previous finding for human touch.

  1. Local Environment and Interactions of Liquid and Solid Interfaces Revealed by Spectral Line Shape of Surface Selective Nonlinear Vibrational Probe

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Shun-Li; Fu, Li; Chase, Zizwe A.; Gan, Wei; Wang, Hong-Fei

    2016-11-10

    Vibrational spectral lineshape contains important detailed information of molecular vibration and reports its specific interactions and couplings to its local environment. In this work, recently developed sub-1 cm-1 high-resolution broadband sum frequency generation vibrational spectroscopy (HR-BB-SFG-VS) was used to measure the -C≡N stretch vibration in the 4-n-octyl-4’-cyanobiphenyl (8CB) Langmuir or Langmuir-Blodgett (LB) monolayer as a unique vibrational probe, and the spectral lineshape analysis revealed the local environment and interactions at the air/water, air/glass, air/calcium fluoride and air/-quartz interfaces for the first time. The 8CB Langmuir or LB film is uniform and the vibrational spectral lineshape of its -C≡N group has been well characterized, making it a good choice as the surface vibrational probe. Lineshape analysis of the 8CB -C≡N stretch SFG vibrational spectra suggests the coherent vibrational dynamics and the structural and dynamic inhomogeneity of the -C≡N group at each interface are uniquely different. In addition, it is also found that there are significantly different roles for water molecules in the LB films on different substrate surfaces. These results demonstrated the novel capabilities of the surface nonlinear spectroscopy in characterization and in understanding the specific structures and chemical interactions at the liquid and solid interfaces in general.

  2. Strong Coupling between Surface Plasmon Polaritons and Molecular Vibrations

    Science.gov (United States)

    Memmi, H.; Benson, O.; Sadofev, S.; Kalusniak, S.

    2017-03-01

    We report on the strong coupling of surface plasmon polaritons and molecular vibrations in an organic-inorganic plasmonic hybrid structure consisting of a ketone-based polymer deposited on top of a silver layer. Attenuated-total-reflection spectra of the hybrid reveal an anticrossing in the dispersion relation in the vicinity of the carbonyl stretch vibration of the polymer with an energy splitting of the upper and lower polariton branch up to 15 meV. The splitting is found to depend on the molecular layer thickness and saturates for micrometer-thick films. This new hybrid state holds a strong potential for application in chemistry and optoelectronics.

  3. Vibrations on the (001) surface of 9R Li

    Science.gov (United States)

    Sklyadneva, I. Yu.; Rusina, G. G.; Chulkov, E. V.

    2002-06-01

    Vibrational modes, surface energy, and surface relaxation on the (001) surface (hexagonal plane type C) of 9R Li are calculated using the embedded-atom method. A detailed discussion of the local phonon densities of states, the changes in interatomic force constants, and a comparison with the results for the hexagonal surface (110) of bcc Li are presented. For both surfaces considered the surface effect on the phonon densities is found to be significant only in the first three layers. The results show that interactions between atomic layers are weaker in the surface region compared to bulk values. This effect together with a substantial softening in the phonon spectrum for the (110) surface of bcc Li may favor the nucleation of the martensitic phase along preferable directions at the surface.

  4. Surface Acoustic Wave Vibration Sensors for Measuring Aircraft Flutter

    Science.gov (United States)

    Wilson, William C.; Moore, Jason P.; Juarez, Peter D.

    2016-01-01

    Under NASA's Advanced Air Vehicles Program the Advanced Air Transport Technology (AATT) Project is investigating flutter effects on aeroelastic wings. To support that work a new method for measuring vibrations due to flutter has been developed. The method employs low power Surface Acoustic Wave (SAW) sensors. To demonstrate the ability of the SAW sensor to detect flutter vibrations the sensors were attached to a Carbon fiber-reinforced polymer (CFRP) composite panel which was vibrated at six frequencies from 1Hz to 50Hz. The SAW data was compared to accelerometer data and was found to resemble sine waves and match each other closely. The SAW module design and results from the tests are presented here.

  5. Tool-specific performance of vibration-reducing gloves for attenuating palm-transmitted vibrations in three orthogonal directions.

    Science.gov (United States)

    Dong, Ren G; Welcome, Daniel E; Peterson, Donald R; Xu, Xueyan S; McDowell, Thomas W; Warren, Christopher; Asaki, Takafumi; Kudernatsch, Simon; Brammer, Antony

    2014-11-01

    Vibration-reducing (VR) gloves have been increasingly used to help reduce vibration exposure, but it remains unclear how effective these gloves are. The purpose of this study was to estimate tool-specific performances of VR gloves for reducing the vibrations transmitted to the palm of the hand in three orthogonal directions (3-D) in an attempt to assess glove effectiveness and aid in the appropriate selection of these gloves. Four typical VR gloves were considered in this study, two of which can be classified as anti-vibration (AV) gloves according to the current AV glove test standard. The average transmissibility spectrum of each glove in each direction was synthesized based on spectra measured in this study and other spectra collected from reported studies. More than seventy vibration spectra of various tools or machines were considered in the estimations, which were also measured in this study or collected from reported studies. The glove performance assessments were based on the percent reduction of frequency-weighted acceleration as is required in the current standard for assessing the risk of vibration exposures. The estimated tool-specific vibration reductions of the gloves indicate that the VR gloves could slightly reduce (<5%) or marginally amplify (<10%) the vibrations generated from low-frequency (<25 Hz) tools or those vibrating primarily along the axis of the tool handle. With other tools, the VR gloves could reduce palm-transmitted vibrations in the range of 5%-58%, primarily depending on the specific tool and its vibration spectra in the three directions. The two AV gloves were not more effective than the other gloves with some of the tools considered in this study. The implications of the results are discussed.

  6. Passive Optical Detection of a Vibrating Surface

    Science.gov (United States)

    2014-01-01

    medium from the incident side without change in frequency; reflectance is the fraction of the incident flux that is reflected.” Nicodemus defines more... differenced the images Figure 2. Bidirectional reflectance distribution function (BRDF) of spectralon (approximately Lambertian) and grass. (Reprinted...However, we have raised more questions than we have answered. For example, what fraction of the detected intensity modulation is from surface normal

  7. Surface instabilities and reorientation induced by vibration in microgravity conditions

    Science.gov (United States)

    Porter, Jeff; Laverón-Simavilla, Ana; Tinao Perez-Miravete, Ignacio; Fernandez Fraile, Jose Javier; Ezquerro Navarro, Jose Miguel

    2012-07-01

    The behavior of vibrated fluids and, in particular, the surface or interfacial instabilities that commonly arise in these systems have been the subject of continued experimental and theoretical attention since Faraday's seminal experiments in 1831. Both orientation and frequency are critical in determining the response of the fluid to excitation. Low frequencies are associated with sloshing while higher frequencies may generate Faraday waves or cross-waves, depending on whether the axis of vibration is perpendicular or parallel to the interface. In addition, high frequency vibrations are known to produce large scale reorientation of the fluid (vibroequilibria), an effect that becomes especially pronounced in the absence of gravity. We describe the results of investigations conducted at the ESA affiliated Spanish User Support and Operations Centre (E-USOC) on the effect of vibrations on fluid interfaces, particularly the interaction between Faraday waves, which arise in vertically vibrated systems, cross-waves, which are found in horizontally forced systems, and large scale reorientation (vibroequilibria). Ongoing ground experiments utilizing a dual-axis shaker configuration are described, including the effect on pattern formation of varying the two independent forcing frequencies, amplitudes, and phases. Theoretical results, based on the analysis of reduced models, and on numerical simulations, are then described and compared to experiment. Finally, the interest of a corresponding microgravity experiment is discussed and implications for fluid management strategies considered.

  8. Surface roughness monitoring by singular spectrum analysis of vibration signals

    Science.gov (United States)

    García Plaza, E.; Núñez López, P. J.

    2017-02-01

    This study assessed two methods for enhanced surface roughness (Ra) monitoring based on the application of singular spectrum analysis (SSA) to vibrations signals generated in workpiece-cutting tool interaction in CNC finish turning operations i.e., the individual analysis of principal components (I-SSA), and the grouping analysis of correlated principal components (G-SSA). Singular spectrum analysis is a non-parametric technique of time series analysis that decomposes a signal into a set of independent additive time series referred to as principal components. A number of experiments with different cutting conditions were performed to assess surface roughness monitoring using both of these methods. The results show that singular spectrum analysis of vibration signal processing discriminated the frequency ranges effective for predicting surface roughness. Grouping analysis of correlated principal components (G-SSA) proved to be the most efficient method for monitoring surface roughness, with optimum prediction and reliability results at a lower analytical-computational cost. Finally, the results show that singular spectrum analysis is an ideal method for analyzing vibration signals applied to the on-line monitoring of surface roughness.

  9. Experimental study on effect of surface vibration on micro textured surfaces with hydrophobic and hydrophilic materials

    Science.gov (United States)

    Yao, Chun-Wei; Lai, Chen-Ling; Alvarado, Jorge L.; Zhou, Jiang; Aung, Kendrick T.; Mejia, Jose E.

    2017-08-01

    Artificial hydrophobic surfaces have been studied in the last ten years in an effort to understand the effects of structured micro- and nano-scale features on droplet motion and self-cleaning mechanisms. Among these structured surfaces, micro-textured surfaces consisting of a combination of hydrophilic and hydrophobic materials have been designed, fabricated and characterized to understand how surface properties and morphology affect enhanced self-cleaning mechanisms. However, use of micro textured surfaces leads to a strong pinning effect that takes place between the droplets and the hydrophobic-hydrophilic edge, leading to a significant contact angle hysteresis effect. This research study focuses on the effects of surface vibrations on droplet shedding at different inclined angles on micro-textured surfaces. Surface vibration and shedding processes were experimentally characterized using a high speed imaging system. Experimental results show that droplets under the influence of surface vibration depict different contour morphologies when vibrating at different resonance frequencies. Moreover, droplet sliding angles can be reduced through surface vibration when the proper combination of droplet size and surface morphology is prescribed.

  10. FUNCTIONAL SURFACE MICROGEOMETRY PROVIDING THE DESIRED PERFORMANCE OF AN AIRCRAFT VIBRATION SENSOR

    Directory of Open Access Journals (Sweden)

    Yuriy S. Andreev

    2016-11-01

    Full Text Available Subject of Research. The paper deals with the methods of efficiency improving for piezoelectric vibration sensors used in aircraft industry to control the level of vibration of gas turbine engines. The study looks into the matter of surface microgeometry effect of the vibro sensor part on its transverse sensitivity ratio. Measures are proposed to improve the sensor performance without cost supplement by optimization of the functional surface microgeometry. Method. A method for determination of the best possible surface microgeometry within the specific production conditions is shown. Also, a method for microgeometry estimation of the functional surfaces using graphical criteria is used. Taguchi method is used for design of experiment for functional surfaces machining. The use of this method reduces significantly the number of experiments without validity loss. Main Results. The relationship between technological factors of manufacturing the vibration sensor parts and its sensitivity has been found out. The optimal surface machining methods and process conditions for parts ensuring the best possible sensitivity have been determined. Practical Relevance. Research results can be used by instrument-making companies to improve the process of piezoelectric vibration sensor design and manufacturing.

  11. Vibration of a carbyne nanomechanical mass sensor with surface effect

    Science.gov (United States)

    Agwa, M. A.; Eltaher, M. A.

    2016-04-01

    This paper presents a comprehensive model to investigate the influence of surface elasticity and residual surface tension on the natural frequency of flexural vibrations of nanomechanical mass sensor using a carbyne resonator. Carbyne is modeled as an equivalent continuum circular cross-section Timoshenko nanobeam including rotary inertia and shear deformation effects. Surface stress and surface elasticity are presented via the Young-Laplace equation. The analytical solution is presented and verified with molecular dynamics solution. The results show that the carbyne resonator can measure a very small mass with weight below 10-3 zg. The effects of surface elasticity, residual surface tension, carbyne length, and mass position on the fundamental frequencies are illustrated. This study is helpful for characterizing the mechanical behavior of high-precision measurement devices such as chemical and biological sensor.

  12. Vibrational properties of the Pt(111)- p(2 × 2)-K surface superstructure

    Science.gov (United States)

    Rusina, G. G.; Eremeev, S. V.; Borisova, S. D.; Chulkov, E. V.

    2008-08-01

    The vibrational spectra of the Pt(111)- p(2 × 2)-K ordered surface superstructure formed on the platinum surface upon adsorption of 0.25 potassium monolayer are calculated using the interatomic interaction potentials obtained within the tight-binding approximation. The surface relaxation, the dispersion of surface phonons, the local density of surface vibrational states, and the polarization of vibrational modes of adatoms and substrate atoms are discussed. The theoretical results are in good agreement with the recently obtained experimental data.

  13. The Investigations of Friction under Die Surface Vibration in Cold Forging Process

    DEFF Research Database (Denmark)

    Jinming, Sha

    is undergoing vibration. In the experiments, die surface orientation, frequency and amplitude of vibration, vibrating wave form and the direction of vibration has been taken into account as the parameters which influence friction behaviour in forging process. The results reveal that friction could be reduced up......The objective of this thesis is to fundamentally study the influence of die surface vibration on friction under low frequency in metal forging processes. The research includes vibrating tool system design for metal forming, theoretical and experimental investigations, and finite element simulations...... on die surface vibration in forging process. After a general introduction to friction mechanisms and friction test techniques in metal forming, the application of ultrasonic vibration in metal forming, the influence of sliding velocity on friction is described. Some earlier investigations...

  14. Automatic generation of force fields and property surfaces for use in variational vibrational calculations of anharmonic vibrational energies and zero-point vibrational averaged properties.

    Science.gov (United States)

    Kongsted, Jacob; Christiansen, Ove

    2006-09-28

    An automatic and general procedure for the calculation of geometrical derivatives of the energy and general property surfaces for molecular systems is developed and implemented. General expressions for an n-mode representation are derived, where the n-mode representation includes only the couplings between n or less degrees of freedom. The general expressions are specialized to derivative force fields and property surfaces, and a scheme for calculation of the numerical derivatives is implemented. The implementation is interfaced to electronic structure programs and may be used for both ground and excited electronic states. The implementation is done in the context of a vibrational structure program and can be used in combination with vibrational self-consistent field (VSCF), vibrational configuration interaction (VCI), vibrational Moller-Plesset, and vibrational coupled cluster calculations of anharmonic wave functions and calculation of vibrational averaged properties at the VSCF and VCI levels. Sample calculations are presented for fundamental vibrational energies and vibrationally averaged dipole moments and frequency dependent polarizabilities and hyperpolarizabilities of water and formaldehyde.

  15. The effect of surface wave propagation on neural responses to vibration in primate glabrous skin.

    Science.gov (United States)

    Manfredi, Louise R; Baker, Andrew T; Elias, Damian O; Dammann, John F; Zielinski, Mark C; Polashock, Vicky S; Bensmaia, Sliman J

    2012-01-01

    Because tactile perception relies on the response of large populations of receptors distributed across the skin, we seek to characterize how a mechanical deformation of the skin at one location affects the skin at another. To this end, we introduce a novel non-contact method to characterize the surface waves produced in the skin under a variety of stimulation conditions. Specifically, we deliver vibrations to the fingertip using a vibratory actuator and measure, using a laser Doppler vibrometer, the surface waves at different distances from the locus of stimulation. First, we show that a vibration applied to the fingertip travels at least the length of the finger and that the rate at which it decays is dependent on stimulus frequency. Furthermore, the resonant frequency of the skin matches the frequency at which a subpopulation of afferents, namely Pacinian afferents, is most sensitive. We show that this skin resonance can lead to a two-fold increase in the strength of the response of a simulated afferent population. Second, the rate at which vibrations propagate across the skin is dependent on the stimulus frequency and plateaus at 7 m/s. The resulting delay in neural activation across locations does not substantially blur the temporal patterning in simulated populations of afferents for frequencies less than 200 Hz, which has important implications about how vibratory frequency is encoded in the responses of somatosensory neurons. Third, we show that, despite the dependence of decay rate and propagation speed on frequency, the waveform of a complex vibration is well preserved as it travels across the skin. Our results suggest, then, that the propagation of surface waves promotes the encoding of spectrally complex vibrations as the entire neural population is exposed to essentially the same stimulus. We also discuss the implications of our results for biomechanical models of the skin.

  16. The effect of surface wave propagation on neural responses to vibration in primate glabrous skin.

    Directory of Open Access Journals (Sweden)

    Louise R Manfredi

    Full Text Available Because tactile perception relies on the response of large populations of receptors distributed across the skin, we seek to characterize how a mechanical deformation of the skin at one location affects the skin at another. To this end, we introduce a novel non-contact method to characterize the surface waves produced in the skin under a variety of stimulation conditions. Specifically, we deliver vibrations to the fingertip using a vibratory actuator and measure, using a laser Doppler vibrometer, the surface waves at different distances from the locus of stimulation. First, we show that a vibration applied to the fingertip travels at least the length of the finger and that the rate at which it decays is dependent on stimulus frequency. Furthermore, the resonant frequency of the skin matches the frequency at which a subpopulation of afferents, namely Pacinian afferents, is most sensitive. We show that this skin resonance can lead to a two-fold increase in the strength of the response of a simulated afferent population. Second, the rate at which vibrations propagate across the skin is dependent on the stimulus frequency and plateaus at 7 m/s. The resulting delay in neural activation across locations does not substantially blur the temporal patterning in simulated populations of afferents for frequencies less than 200 Hz, which has important implications about how vibratory frequency is encoded in the responses of somatosensory neurons. Third, we show that, despite the dependence of decay rate and propagation speed on frequency, the waveform of a complex vibration is well preserved as it travels across the skin. Our results suggest, then, that the propagation of surface waves promotes the encoding of spectrally complex vibrations as the entire neural population is exposed to essentially the same stimulus. We also discuss the implications of our results for biomechanical models of the skin.

  17. Surface cleanliness of fluid systems, specification for

    Science.gov (United States)

    1995-01-01

    This specification establishes surface cleanliness levels, test methods, cleaning and packaging requirements, and protection and inspection procedures for determining surface cleanliness. These surfaces pertain to aerospace parts, components, assemblies, subsystems, and systems in contact with any fluid medium.

  18. Radial vibration measurements directly from rotors using laser vibrometry: The effects of surface roughness, instrument misalignments and pseudo-vibration

    Science.gov (United States)

    Rothberg, Steve J.; Halkon, Ben J.; Tirabassi, Mario; Pusey, Chris

    2012-11-01

    Laser Doppler vibrometry (LDV) offers an attractive solution when radial vibration measurement directly from a rotor surface is required. Research to date has demonstrated application on polished-circular rotors and rotors coated with retro-reflective tape. In the latter case, however, a significant cross-sensitivity to the orthogonal radial vibration component occurs and post-processing is required to resolve individual radial vibration components. Until now, the fundamentally different behaviour observed between these cases has stood as an inconsistency in the published literature, symptomatic of the need to understand the effect of surface roughness. This paper offers the first consistent mathematical description of the polished-circular and rough rotor behaviours, combined with an experimental investigation of the relationship between surface roughness and cross-sensitivity. Rotors with surface roughness up to 10 nm satisfy the polished-circular rotor definition if vibration displacement is below 100% beam diameter, for a 90 μm beam, and below 40% beam diameter, for a 520 μm beam. On rotors with roughness between 10 nm and 50 nm, the polished-circular rotor definition is satisfied for vibration displacements up to 25% beam diameter, for a 90 μm beam, and up to 10% beam diameter, for a 520 μm beam. As roughness increases, cross-sensitivity increases but only rotors coated in retro-reflective tape satisfied the rough rotor definition fully. Consequently, when polished-circular surfaces are not available, rotor surfaces must be treated with retro-reflective tape and measurements post-processed to resolve individual vibration components. Through simulations, the value of the resolution and correction algorithms that form the post-processor has been demonstrated quantitatively. Simulations incorporating representative instrument misalignments and measurement noise have enabled quantification of likely error levels in radial vibration measurements. On a polished

  19. Nanoscopic Vibrations of Bacteria with Different Cell-Wall Properties Adhering to Surfaces under Flow and Static Conditions

    NARCIS (Netherlands)

    Song, Lei; Sjollema, Jelmer; Sharma, Prashant K.; Kaper, Hans J.; van der Mei, Henny C.; Busscher, Henk J.

    Bacteria adhering to surfaces demonstrate random, nanoscopic vibrations around their equilibrium positions. This paper compares vibrational amplitudes of bacteria adhering to glass. Spring constants of the bond are derived from vibrational amplitudes and related to the electrophoretic softness of

  20. Vibration analysis based on surface acoustic wave sensors

    Directory of Open Access Journals (Sweden)

    Gnadinger Alfred P.

    2015-01-01

    Full Text Available It is important to know, whether a civil engineering structure is safe or unsafe. One way to determine this is to measure vibrations at critical locations and feeding this data into an appropriate algorithm. Albido Corporation has developed wireless strain sensors based on surface acoustic wave (SAW principles that are mainly employed on rotating structures and in harsh environments. Albido's sensors could also be used to measure vibrations in civil engineering structures. They are small (~1 × 3 mm, passive and inexpensive (< 1$ in volume. They are powered by the electromagnetic field emanating from the antenna of a Reader System, similar to an RFID. The Reader System is essentially a computer with special software and has signal processing capability. One Reader System can service a multitude of sensors. The Reader antenna has to be within the reading range of the sensor. If large distances are required, a small electronic component acting as a Reader System can be placed within the reading range of the sensor that receives the sensor signal, generates a radio signal and encodes the sensor information on the radio signal. Then, the final data processing center can be placed anywhere.

  1. Mitigating ground vibration by periodic inclusions and surface structures

    DEFF Research Database (Denmark)

    Andersen, Lars Vabbersgaard; Bucinskas, Paulius; Persson, Peter

    2016-01-01

    Ground vibration from traffic is a source of nuisance in urbanized areas. Trenches and wave barriers can provide mitigation of vibrations, but single barriers need to have a large depth to be effective-especially in the low-frequency range relevant to traffic-induced vibration. Alternatively, per...

  2. Non-contact measurement of facial surface vibration patterns during singing by scanning laser Doppler vibrometer.

    Science.gov (United States)

    Kitamura, Tatsuya; Ohtani, Keisuke

    2015-01-01

    This paper presents a method of measuring the vibration patterns on facial surfaces by using a scanning laser Doppler vibrometer (LDV). The surfaces of the face, neck, and body vibrate during phonation and, according to Titze (2001), these vibrations occur when aerodynamic energy is efficiently converted into acoustic energy at the glottis. A vocalist's vibration velocity patterns may therefore indicate his or her phonatory status or singing skills. LDVs enable laser-based non-contact measurement of the vibration velocity and displacement of a certain point on a vibrating object, and scanning LDVs permit multipoint measurements. The benefits of scanning LDVs originate from the facts that they do not affect the vibrations of measured objects and that they can rapidly measure the vibration patterns across planes. A case study is presented herein to demonstrate the method of measuring vibration velocity patterns with a scanning LDV. The objective of the experiment was to measure the vibration velocity differences between the modal and falsetto registers while three professional soprano singers sang sustained vowels at four pitch frequencies. The results suggest that there is a possibility that pitch frequency are correlated with vibration velocity. However, further investigations are necessary to clarify the relationships between vibration velocity patterns and phonation status and singing skills.

  3. Computer simulation structure and vibrations of small metal cluster on the Cu (111) surface

    Science.gov (United States)

    Borisova, Svetlana D.; Rusina, Galina G.

    2015-10-01

    Vibrational properties of the small tetrahedral cluster of Co on the Cu (111) surface are studied by using tight-binding second moment approximation interatomic interaction potentials. It was shown that interaction of the clusters with substrate leads to arising of frustrated translation and frustrated rotation in-plane polarized vibrational modes localized on the cluster atoms. The Co4 cluster on the surface the high frequency modes remain strongly localized and mixed with the nearest neighbor atoms vibrations.

  4. Computer simulation structure and vibrations of small metal cluster on the Cu (111) surface

    Energy Technology Data Exchange (ETDEWEB)

    Borisova, Svetlana D., E-mail: svbor@ispms.tsc.ru; Rusina, Galina G., E-mail: rusina@ispms.tsc.ru [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); National Research Tomsk State University, Tomsk 634050 (Russian Federation)

    2015-10-27

    Vibrational properties of the small tetrahedral cluster of Co on the Cu (111) surface are studied by using tight-binding second moment approximation interatomic interaction potentials. It was shown that interaction of the clusters with substrate leads to arising of frustrated translation and frustrated rotation in-plane polarized vibrational modes localized on the cluster atoms. The Co{sub 4} cluster on the surface the high frequency modes remain strongly localized and mixed with the nearest neighbor atoms vibrations.

  5. Controlled locomotion of robots driven by a vibrating surface

    Science.gov (United States)

    Umbanhowar, Paul; Lynch, Kevin M.

    Robots typically derive their powers of movement from onboard actuators and power sources, but other scenarios are possible where the external environment provides part or all of the necessary forcing and control. I will discuss details of a system where the ``robots'' are just planar solid objects and the requisite driving forces originate from frictional sliding-interactions with a periodically oscillated and nominally horizontal surface. For the robots to move, the temporal symmetry of the frictional forces must be broken, which is achieved here by modulating the normal force using vertical acceleration of the surface. Independent of the initial conditions and vibration waveform, a sliding locomotor reaches a unique velocity limit cycle at a given position. Its resulting motion can be described in terms of velocity fields which specify the robot's cycle-averaged velocity as a function of position. Velocity fields with non-zero spatial divergence can be generated by combining translational and rotational surface motions; this allows the simultaneous and open-loop collection, dispersal, and transport of multiple robots. Fields and field sequences can simultaneously move multiple robots between arbitrary positions and, potentially, along arbitrary trajectories. Supported by NSF CMMI #0700537.

  6. Gold micro- and nano-particles for surface enhanced vibrational spectroscopy of pyridostigmine bromide

    DEFF Research Database (Denmark)

    Dolgov, Leonid; Fesenko, Olena; Kavelin, Vladyslav

    2017-01-01

    Triangular gold microprisms and spherical silica nanoparticles with attached gold nano-islands were examined as an active nanostructures for the surface enhanced Raman and infrared spectroscopy. These particles were probed for the detection of pyridostigmine bromide as a safe analog of military...... compound sarin. Raman and infrared spectral bands of the pyridostigmine bromide were measured. Detailed correlation of obtained spectral bands with specific vibrations in pyridostigmine bromide was done. Silica nanoparticles with attached gold nano-islands showed more essential enhancement of the Raman...

  7. Reduced Heat Flux Through Preferential Surface Reactions Leading to Vibrationally and Electronically Excited Product States

    Science.gov (United States)

    2016-03-04

    AFRL-AFOSR-VA-TR-2016-0124 Reduced Heat Flux Through Preferential Surface Reactions Leading to Vibrationally and Electronically Excited Product...Reactions Leading to Vibrationally and Electronically Excited Product States 5a. CONTRACT NUMBER FA9550-12-1-0486 5b. GRANT NUMBER 5c. PROGRAM... Leading to Vibrationally and Electronically Excited Product States FINAL TECHNICAL REPORT: Grant #FA9550-12-1-0486 2013 Basic Research Initiative (BRI

  8. [Changes in specific sensation in pilots exposed to systematic general vibration].

    Science.gov (United States)

    Podshivalov, A A; Krylov, Iu V; Zaritskiĭ, V V

    1995-01-01

    Helicopter pilots exposed to excessive general vibration demonstrate changes of specific sensation (vibrotactile, vestibular, auditory), that could be signs of occupational disorder. Those changes are increased thresholds of vibrotactile sensation, lower vestibulovegetative stability, changed vestibulospinal reflexes, more common occurrence of consistent deafness for voice frequencies in comparison with jet aircraft pilots. Experimental vibration (50-1,800 (m/s2) 2 hour) caused no changes of the vibrotactile and auditory sensation, and the modified vestibular function could prove the increased vestibular reactivity.

  9. Analyses of transverse vibrations of axially pretensioned viscoelastic nanobeams with small size and surface effects

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yongqiang [College of Civil Engineering and Architecture, Zhejiang University, Hangzhou 310058 (China); State Key Laboratory of Mechanical Structural Strength and Vibration, Xi' an Jiaotong University, Xi' an 710049 (China); Pang, Miao, E-mail: ppmmzju@163.com [College of Civil Engineering and Architecture, Zhejiang University, Hangzhou 310058 (China); Fan, Lifeng [College of Civil Engineering and Architecture, Zhejiang University, Hangzhou 310058 (China)

    2016-07-01

    The general governing equation for transverse vibration of an axially pretensioned viscoelastic nanobeam embedded in elastic substrate medium is formulated on the basis of the Bernoulli–Euler beam theory and the Kelvin model. The factors of structural damping, initial axial tension, surrounding medium, small size, surface elasticity and residual surface tension are incorporated in the formulation. The explicit expression is obtained for the vibrational frequency of a simply supported nanobeam. The impacts of these factors on the properties of transverse vibration of the nanobeam are discussed. It is demonstrated that the dependences of natural frequency on the structural damping, surrounding medium, small size, surface elasticity and residual surface tension are significant, whereas the effect of initial axial tension on the natural frequency is limited. In addition, it can be concluded that the energy dissipation of transverse vibration of the viscoelastic nanobeam is related to the small size effect and structural damping. - Highlights: • The properties of transverse vibration of a pretensioned embedded viscoelastic nanobeam is investigated. • The vibrational equation is formulated based on Bernoulli–Euler beam theory and Kelvin model. • Explicit expression for the complex vibrational frequency is obtained. • Small size and surface effects on vibrational frequency are discussed. • Influences of structural damping, initial axial tension and surrounding medium are analyzed.

  10. The influence of vibrations on surface roughness formed during precision boring

    Science.gov (United States)

    Korzeniewski, Dariusz; Znojkiewicz, Natalia

    2017-01-01

    In this paper, the analysis of vibrations on surface roughness generated during boring with the application of the conventional boring tool and one with the damper is presented. The experiments included the measurement of vibration accelerations carried out with the piezoelectric sensor, as well as the evaluation of surface roughness parameters after each machining pass. The obtained results reveal that in the investigated range, no stability loss was found. Furthermore, the growth of the rotational speed induces the increase of vibration level, as well as the growth of the differences between the vibration values generated during boring with the conventional tool and one equipped with damper. Vibrations have also the direct influence on the machined surface roughness. In case of the tool equipped with the damper, the tool's overhang L had more intense influence than rotational speed n. However, for the conventional boring tool this dependency was unequivocal.

  11. Vibrations of small cobalt clusters on low-index surfaces of copper: Tight-binding simulations

    Science.gov (United States)

    Borisova, S. D.; Eremeev, S. V.; Rusina, G. G.; Stepanyuk, V. S.; Bruno, P.; Chulkov, E. V.

    2008-08-01

    Vibrational properties (frequencies, polarizations, and lifetimes) of a single adatom, dimer, and trimer of Co on low-index Cu surfaces, Cu(111), Cu(001), and Cu(110) are studied by using tight-binding second moment approximation interatomic interaction potentials. We show that structural and vibrational properties of the Co clusters strongly depend on the substrate orientation. The longest lifetimes of 1-2.5 ps have been found for high-frequency z -polarized vibrations in all the Co clusters considered. The shortest lifetimes of 0.1-0.8 ps have been obtained for low-frequency horizontal (frustrated translation) vibrational modes.

  12. Influence of the surface structure and vibration mode on the resistivity of Cu films

    Science.gov (United States)

    Zhao, Ya-Ni; Qu, Shi-Xian; Xia, Ke

    2011-09-01

    The influence of the surface structure and vibration mode on the resistivity of Cu films and the corresponding size effect are investigated. The temperature dependent conductivities of the films with different surface morphologies are calculated by the algorithm based upon the tight-binding linear muffin-tin orbital method and the Green's function technique. The thermal effect is introduced by setting the atomic displacements according to the Gaussian distribution with the mean-square amplitude estimated by the Debye model. The result shows that the surface atomic vibration contributes significantly to the resistivity of the system. Comparing the conductivities for three different vibration modes, we suggest that freezing the surface vibration is necessary for practical applications to reduce the resistivity induced by the surface electron-phonon scattering.

  13. DIAGNOSTICS OF WORKPIECE SURFACE CONDITION BASED ON CUTTING TOOL VIBRATIONS DURING MACHINING

    Directory of Open Access Journals (Sweden)

    Jerzy Józwik

    2015-05-01

    Full Text Available The paper presents functional relationships between surface geometry parameters, feed and vibrations level in the radial direction of the workpiece. Time characteristics of the acceleration of cutting tool vibration registered during C45 steel and stainless steel machining for separate axes (X, Y, Z were presented as a function of feedrate f. During the tests surface geometric accuracy assessment was performed and 3D surface roughness parameters were determined. The Sz parameter was selected for the analysis, which was then collated with RMS vibration acceleration and feedrate f. The Sz parameter indirectly provides information on peak to valley height and is characterised by high generalising potential i.e. it is highly correlated to other surface and volume parameters of surface roughness. Test results presented in this paper may constitute a valuable source of information considering the influence of vibrations on geometric accuracy of elements for engineers designing technological processes.

  14. 3D Characteristic Diagram of Acoustically Induced Surface Vibration with Different Landmines Buried

    Institute of Scientific and Technical Information of China (English)

    吴智强; 张燕丽; 王驰; 朱俊; 徐文文; 袁志文

    2016-01-01

    The 3Dcharacteristic diagram of acoustically induced surface vibration was employed to study the influence of different buried landmines on the acoustic detection signal. By using the vehicular experimental system for acoustic landmine detection and the method of scanning detection, the 3D characteristic diagrams of surface vibration were measured when different objects were buried underground, including big plastic landmine, small plastic landmine, big metal landmine and bricks. The results show that, under the given conditions, the surface vi-bration amplitudes of big plastic landmine, big metal landmine, small plastic landmine and bricks decrease in turn. The 3D characteristic diagrams of surface vibration can be used to further identify the locations of buried land-mines.

  15. Vibrational properties of small cobalt clusters on the Cu(111) surface

    Science.gov (United States)

    Borisova, S. D.; Rusina, G. G.; Eremeev, S. V.; Chulkov, E. V.

    2009-06-01

    Vibrational properties of small cobalt clusters (dimer and trimer) adsorbed on the Cu(111) surface are studied using interatomic interaction potentials obtained in a tight-binding approximation. The complete (lateral and vertical) relaxation of the surface, the local phonon density of states, and the polarization of vibration modes of clusters and atoms of the substrate are discussed. It is shown that the adsorption of small cobalt clusters leads to a local modification of the vibrational properties of the substrate surface and to excitation of new vibration modes localized on both the cluster adatoms and substrate surface atoms. An increase in the cluster size causes a decrease in the intensity of peaks of the local density of states and their broadening and also a shift in the frequencies of the peaks.

  16. Measuring Work Functions Of "Dirty" Surfaces With A Vibrating Capacitive Probe

    Science.gov (United States)

    Yost, William T.

    1995-01-01

    Apparatus measures work function of possibly contaminated surface of specimen of metal or other electrically conductive material. Measures work function of specimen indirectly, by vibrating capacitive measurement of contact potential. Work function of specimen affected by microstructure and by contamination.

  17. Investigation of sandwich material surface created by abrasive water jet (AWJ via vibration emission

    Directory of Open Access Journals (Sweden)

    P. Hreha

    2014-01-01

    Full Text Available The paper presents research a of abrasive waterjet cutting of heterogeneous “sandwich“ material with different Young modulus of elasticity of the cutted surface geometry by means of vibration emission. In order to confirm hypothetical assumptions about direct relation between vibration emission and surface quality an experiment in heterogeneous material consisting of stainless steel (DIN 1.4006 / AISI 410 and alloy AlCuMg2 has been provided.

  18. ELECTRIC ARC WELDING DEPOSITION OF METALLIC SURFACES BY VIBRATING ELECTRODE IN PROTECTIVE GAS MEDIUM

    Directory of Open Access Journals (Sweden)

    N. Spiridonov

    2013-01-01

    Full Text Available The paper presents methods for obtaining qualitative metallic surfaces by electric arc welding deposition while using consumable electrode in a protective gas medium and executing regularized drop transfer of electrode metal. The drop transfer efficiency of electrode metal and productivity of welding deposition are significantly increased due to excitation of lateral vibrations in the consumable electrode with preset amplitude. The paper describes a method and a device for welding deposition of metallic surfaces by vibrating  electrode where vibrations are excited by ultrasound.

  19. Pulse-induced acoustoelectric vibrations in surface-gated GaAs-based quantum devices

    Science.gov (United States)

    Rahman, S.; Stace, T. M.; Langtangen, H. P.; Kataoka, M.; Barnes, C. H. W.

    2007-05-01

    We present the results of a numerical investigation which show the excitation of acoustoelectric modes of vibration in GaAs-based heterostructures due to sharp nanosecond electric-field pulses applied across surface gates. In particular, we show that the pulses applied in quantum information processing applications are capable of exciting acoustoelectric modes of vibration including surface acoustic modes which propagate for distances greater than conventional device dimensions. We show that the pulse-induced acoustoelectric vibrations are capable of inducing significant undesired perturbations to the evolution of quantum systems.

  20. Dynamic behavior of a vibrated droplet on a low-temperature micropillared surface

    Science.gov (United States)

    Tan, Chen-chuan; Jia, Zhi-hai; Yang, Hui-nan; Zhang, Zhi-tao

    2017-02-01

    The dynamic behavior of a vibrated droplet on a micropillared hydrophobic surface under low temperature was investigated in this paper. It was observed that solidified time of droplets on the micropillared surface were much larger than on the smooth surface due to the existence of wetting transition at low temperature, without vibration. The solidified time of droplets was longer while vibration was exerted on the surfaces, even though the wetting transition time of droplets at low temperature was shorter than at room temperature. It was found that resonance frequency of droplet increased as surface tension increased due to low temperature. Moreover, when a droplet was in its resonance frequency, the wetting area between the droplet and the micropillared surface increased obviously and its solidified time decreased substantially, and it led to the decline of anti-icing performance. This work is helpful to design a more efficient anti-icing device.

  1. Optimization of Surface Finish in Turning Operation by Considering the Machine Tool Vibration using Taguchi Method

    Directory of Open Access Journals (Sweden)

    Muhammad Munawar

    2012-01-01

    Full Text Available Optimization of surface roughness has been one of the primary objectives in most of the machining operations. Poor control on the desired surface roughness generates non conforming parts and results into increase in cost and loss of productivity due to rework or scrap. Surface roughness value is a result of several process variables among which machine tool condition is one of the significant variables. In this study, experimentation was carried out to investigate the effect of machine tool condition on surface roughness. Variable used to represent machine tool\\'s condition was vibration amplitude. Input parameters used, besides vibration amplitude, were feed rate and insert nose radius. Cutting speed and depth of cut were kept constant. Based on Taguchi orthogonal array, a series of experimentation was designed and performed on AISI 1040 carbon steel bar at default and induced machine tool\\'s vibration amplitudes. ANOVA (Analysis of Variance, revealed that vibration amplitude and feed rate had moderate effect on the surface roughness and insert nose radius had the highest significant effect on the surface roughness. It was also found that a machine tool with low vibration amplitude produced better surface roughness. Insert with larger nose radius produced better surface roughness at low feed rate.

  2. Temperature dependence of lattice vibrations and analysis of specific heat in graphite. Cooperative research

    Energy Technology Data Exchange (ETDEWEB)

    Nihira, Takeshi; Iwata, Tadao; Iwase, Akihiro [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2001-11-01

    The semi-continuum model of lattice vibrations of graphite proposed by Komatsu and Nagamiya is the only one that has succeeded in expressing analytically the dispersion relation of lattice vibrations. The expressions of the dispersion relation contain the interlayer spacing, c, and the elastic constants, C{sub 11}, C{sub 12}, C{sub 13}, C{sub 33}, C{sub 44} and {kappa}, as parameters, where c{rho}{kappa}{sup 2} is the bending elastic constants of a graphite layer and {rho} is the density. We improve the semi-continuum model by taking these parameters as a function of temperature. For the parameters except {kappa}, we use the experimental data already known and the relations derived from them. {kappa} is derived as a function of temperature by fitting the calculated specific heat to the experimental one. The improved semi-continuum model can explain the specific heat well in the temperature range below 360 K and be reliably used there for the analysis of thermal conductivity, etc.. {kappa} decreases largely with temperature increasing, which means that there occurs the softening of the out-of-plane vibration. The second derivative of the experimental specific heat curve with respect to temperature gives information on the frequency distribution of lattice vibrations. From the analysis of the low-temperature specific heat, the value of C{sub 44} at room temperature is determined to be 0.415 x 10{sup 11} dyn/cm{sup 2}. (author)

  3. S-shape spring sensor: Sensing specific low-frequency vibration by energy harvesting

    Science.gov (United States)

    Zhang, Lan; Lu, Jian; Takei, Ryohei; Makimoto, Natsumi; Itoh, Toshihiro; Kobayashi, Takeshi

    2016-08-01

    We have developed a Si-based microelectromechanical systems sensor with high sensitivity for specific low-frequency vibration-sensing and energy-harvesting applications. The low-frequency vibration sensor contains a disk proof mass attached to two or three lead zirconate titanate (PZT) S-shape spring flexures. To obtain a faster and less expensive prototype, the design and optimization of the sensor structure are studied via finite-element method analysis. To validate the sensor structure to detect low-frequency vibration, the effects of geometrical dimensions, including the width and diameter of the S-shape spring of the proof mass, were analyzed and measured. The functional features, including the mechanical property and electrical performance of the vibration sensor, were evaluated. The results demonstrated that a very low resonant frequency of 0.2g can be typically achieved. Given a low-frequency vibration sensor with ideal performance and mass fabrication, many advanced civilian and industrial applications can be possibly realized.

  4. S-shape spring sensor: Sensing specific low-frequency vibration by energy harvesting.

    Science.gov (United States)

    Zhang, Lan; Lu, Jian; Takei, Ryohei; Makimoto, Natsumi; Itoh, Toshihiro; Kobayashi, Takeshi

    2016-08-01

    We have developed a Si-based microelectromechanical systems sensor with high sensitivity for specific low-frequency vibration-sensing and energy-harvesting applications. The low-frequency vibration sensor contains a disk proof mass attached to two or three lead zirconate titanate (PZT) S-shape spring flexures. To obtain a faster and less expensive prototype, the design and optimization of the sensor structure are studied via finite-element method analysis. To validate the sensor structure to detect low-frequency vibration, the effects of geometrical dimensions, including the width and diameter of the S-shape spring of the proof mass, were analyzed and measured. The functional features, including the mechanical property and electrical performance of the vibration sensor, were evaluated. The results demonstrated that a very low resonant frequency of 0.2g can be typically achieved. Given a low-frequency vibration sensor with ideal performance and mass fabrication, many advanced civilian and industrial applications can be possibly realized.

  5. Vertically-Vibrated Gas-Liquid Interfaces: Surface Deformation and Breakup

    CERN Document Server

    O'Hern, T J; Brooks, C F; Shelden, B; Torczynski, J R; Kraynik, A M; Romero, L A; Benavides, G L

    2010-01-01

    In his pioneering work of 1831, Faraday demonstrated that a vertically vibrated gas-liquid interface exhibits a period-doubling bifurcation from a flat state to a wavy configuration at certain frequencies or amplitudes. Typical experiments performed using thin layers of water produce "Faraday ripples", modest-amplitude nonlinear standing waves. Later experiments by Hashimoto and Sudo (1980) and Jameson (1966) as well as those performed in the present study show that much more dramatic disturbances can be generated at the gas-liquid free surface under certain ranges of vibration conditions. This breakup mechanism was examined experimentally using deep layers of polydimethylsiloxane (PDMS) silicone oils over a range of viscosity and sinusoidal, primarily axial vibration conditions that can produce dramatic disturbances at the gas-liquid free surface. Large-amplitude vibrations produce liquid jets into the gas, droplets pinching off from the jets, gas cavities in the liquid from droplet impact, and bubble transp...

  6. Small Al clusters on the Cu(111) surface: Atomic relaxation and vibrational properties

    Science.gov (United States)

    Rusina, G. G.; Borisova, S. D.; Chulkov, E. V.

    2010-11-01

    The relaxation and vibrational properties of both Al clusters and the (111) surface of a copper sub-strate were studied using the interatomic interaction potentials obtained in a tight-binding approximation. The presence of small aluminum clusters led to modification of the vibrational states of the substrate, a shift of the Rayleigh mode, and excitation of new Z-polarized modes. Hybridized modes localized on the cluster adatoms and the neighboring atoms of the substrate were found in the phonon spectrum. The localized dipole-active modes of the cluster and their strong hybridization with vibrations of the substrate points to desorption stability of the tri- and heptaatomic clusters.

  7. Effects of vertical vibration on surface intruder loading in a multiple-size granular system

    Directory of Open Access Journals (Sweden)

    Hou Wenqing

    2017-01-01

    Full Text Available We investigate the behaviors of the large porous-alumina particles on the free surface of the small glass-grain system under vertical vibration. The experiments are performed using cylindrical container with diameter Φ = 240 mm, loaded with small glass beads to a static depth h =100 mm. We control the shaker to vibrate at the various frequencies f, from 40 to 80 Hz, and dimensionless acceleration Γ = (4π2Af2/g from 2 to 6. When the glass granular system is at rest, porous alumina particles are placed on its free surface. A parameter critical frequency fu is defined to distinguish two kinds of diffusion in particles. When the vibration frequency is less than fu, quasi-two-dimensional surface diffusion can occur in porous alumina particles, surface granules clusters formed under certain condition. The frequency and dimensionless acceleration of the vibration are varied to view their effect on the clustering and surface particle-distribution. When the vibration frequency is larger than fu, the surface diffusion disappears and a three-dimensional diffusion appears.

  8. Vibrational fingerprinting of bacterial pathogens by surface enhanced Raman scattering (SERS)

    Science.gov (United States)

    Premasiri, W. Ranjith; Moir, D. T.; Ziegler, Lawrence D.

    2005-05-01

    The surface enhanced Raman scattering (SERS) spectra of vegetative whole-cell bacteria were obtained using in-situ grown gold nanoparticle cluster-covered silicon dioxide substrates excited at 785 nm. SERS spectra of Gram-negative bacteria; E. coli and S. typhimurium, and Gram-positive bacteria; B. subtilis, B. cereus, B. thuringeinsis and B. anthracis Sterne, have been observed. Raman enhancement factors of ~104-105 per cell are found for both Gram positive and Gram negative bacteria on this novel SERS substrate. The bacterial SERS spectra are species specific and exhibit greater species differentiation and reduced spectral congestion than their corresponding non-SERS (bulk) Raman spectra. Fluorescence observed in the 785 nm excited bulk Raman emission of Bacillus species is not apparent in the corresponding SERS spectra. The surface enhancement effect allows the observation of Raman spectra at the single cell level excited by low incident laser powers (blood serum, has an observable effect on the bacterial SERS spectra. However, reproducible, species specific SERS vibrational fingerprints are still obtained. The potential of SERS for detection and identification of bacteria with species specificity on these gold nanoparticle coated substrates is demonstrated by these results.

  9. Expansion Hamiltonian model for a diatomic molecule adsorbed on a surface: Vibrational states of the CO/Cu(100) system including surface vibrations.

    Science.gov (United States)

    Meng, Qingyong; Meyer, Hans-Dieter

    2015-10-28

    Molecular-surface studies are often done by assuming a corrugated, static (i.e., rigid) surface. To be able to investigate the effects that vibrations of surface atoms may have on spectra and cross sections, an expansion Hamiltonian model is proposed on the basis of the recently reported [R. Marquardt et al., J. Chem. Phys. 132, 074108 (2010)] SAP potential energy surface (PES), which was built for the CO/Cu(100) system with a rigid surface. In contrast to other molecule-surface coupling models, such as the modified surface oscillator model, the coupling between the adsorbed molecule and the surface atoms is already included in the present expansion SAP-PES model, in which a Taylor expansion around the equilibrium positions of the surface atoms is performed. To test the quality of the Taylor expansion, a direct model, that is avoiding the expansion, is also studied. The latter, however, requests that there is only one movable surface atom included. On the basis of the present expansion and direct models, the effects of a moving top copper atom (the one to which CO is bound) on the energy levels of a bound CO/Cu(100) system are studied. For this purpose, the multiconfiguration time-dependent Hartree calculations are carried out to obtain the vibrational fundamentals and overtones of the CO/Cu(100) system including a movable top copper atom. In order to interpret the results, a simple model consisting of two coupled harmonic oscillators is introduced. From these calculations, the vibrational levels of the CO/Cu(100) system as function of the frequency of the top copper atom are discussed.

  10. Expansion Hamiltonian model for a diatomic molecule adsorbed on a surface: Vibrational states of the CO/Cu(100) system including surface vibrations

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Qingyong, E-mail: mengqingyong@dicp.ac.cn [State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Zhongshan Road 457, 116023 Dalian (China); Meyer, Hans-Dieter, E-mail: hans-dieter.meyer@pci.uni-heidelberg.de [Theoretische Chemie, Physikalisch-Chemisches Institut, Ruprecht-Karls Universität Heidelberg, Im Neuenheimer Feld 229, D-69120 Heidelberg (Germany)

    2015-10-28

    Molecular-surface studies are often done by assuming a corrugated, static (i.e., rigid) surface. To be able to investigate the effects that vibrations of surface atoms may have on spectra and cross sections, an expansion Hamiltonian model is proposed on the basis of the recently reported [R. Marquardt et al., J. Chem. Phys. 132, 074108 (2010)] SAP potential energy surface (PES), which was built for the CO/Cu(100) system with a rigid surface. In contrast to other molecule-surface coupling models, such as the modified surface oscillator model, the coupling between the adsorbed molecule and the surface atoms is already included in the present expansion SAP-PES model, in which a Taylor expansion around the equilibrium positions of the surface atoms is performed. To test the quality of the Taylor expansion, a direct model, that is avoiding the expansion, is also studied. The latter, however, requests that there is only one movable surface atom included. On the basis of the present expansion and direct models, the effects of a moving top copper atom (the one to which CO is bound) on the energy levels of a bound CO/Cu(100) system are studied. For this purpose, the multiconfiguration time-dependent Hartree calculations are carried out to obtain the vibrational fundamentals and overtones of the CO/Cu(100) system including a movable top copper atom. In order to interpret the results, a simple model consisting of two coupled harmonic oscillators is introduced. From these calculations, the vibrational levels of the CO/Cu(100) system as function of the frequency of the top copper atom are discussed.

  11. Effect of surface layer thickness on buckling and vibration of nonlocal nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Kai-Ming; Zhang, Wen-Ming, E-mail: wenmingz@sjtu.edu.cn; Zhong, Zuo-Yang; Peng, Zhi-Ke; Meng, Guang

    2014-01-31

    In this Letter, the buckling and vibration behavior of nonlocal nanowires by incorporating surface elasticity is investigated. A modified core–shell model is developed to depict the size effect of Young's modulus and validated by the reported experimental data. Our results show that the buckling load and natural frequency of nanowires increase when the effect of surface layer thickness is taken into account. Moreover, as the diameter of nanowires is smaller than 50 nm, the influence of surface layer thickness becomes obvious. This work can be helpful in characterizing and predicting the buckling and vibration behavior of NWs.

  12. Effects of tibialis anterior vibration on postural control when exposed to support surface translations.

    Science.gov (United States)

    Temple, David R; Lee, Beom-Chan; Layne, Charles S

    2016-03-01

    The sensory re-weighting theory suggests unreliable inputs may be down-weighted to favor more reliable sensory information and thus maintain proper postural control. This study investigated the effects of tibialis anterior (TA) vibration on center of pressure (COP) motion in healthy individuals exposed to support surface translations to further explore the concept of sensory re-weighting. Twenty healthy young adults stood with eyes closed and arms across their chest while exposed to randomized blocks of five trials. Each trial lasted 8 s, with TA vibration either on or off. After 2 s, a sudden backward or forward translation occurred. Anterior-posterior (A/P) COP data were evaluated during the preparatory (first 2 s), perturbation (next 3 s), and recovery (last 3 s) phases to assess the effect of vibration on perturbation response features. The knowledge of an impending perturbation resulted in reduced anterior COP motion with TA vibration in the preparatory phase relative to the magnitude of anterior motion typically observed during TA vibration. During the perturbation phase, vibration did not influence COP motion. However, during the recovery phase vibration induced greater anterior COP motion than during trials without vibration. The fact that TA vibration produced differing effects on COP motion depending upon the phase of the perturbation response may suggest that the immediate context during which postural control is being regulated affects A/P COP responses to TA vibration. This indicates that proprioceptive information is likely continuously re-weighted according to the context in order to maintain effective postural control.

  13. Effect of axial vibration on free surface flows in cylindrical liquid

    Institute of Scientific and Technical Information of China (English)

    Pan Xiu-Hong; Jin Wei-Qing

    2005-01-01

    The influence of axial vibration on free surface flows in an open cylindrical container was studied by optical in situ observation method under isothermal conditions. This ground-based experiment was performed on an electromagnetic vibrator with oscillatory frequency of 100Hz. Water-glycerol mixture was chosen as the model liquid. Results showed that small amplitude (< 100μm) could generate a new type of steady streaming flows on a free surface, which were mainly driven by the combination of propagating surface wave and Stokes layer effect. The steady flow manifested various patterns according to the vibration amplitude level. Higher amplitude made steady flow periodical or turbulent,which could be characterized by the critical vibrational dimensionless Reynolds number (Nre)c. The calculated value of (Nre)c was of the magnitude of 10-2 - 10-1. In addition, surface streaming velocities were measured by the particle scattering technique. It was found that the velocity increased parabolically with vibration amplitude and decreased with viscosity for a fixed flow pattern.

  14. Surface Topography of Fine-grained ZrO2 Ceramic by Two-dimensional Ultrasonic Vibration Grinding

    Institute of Scientific and Technical Information of China (English)

    DING Ailing; WU Yan; LIU Yongjiang

    2011-01-01

    The surface quality of fine-grained ZrO2 engineering ceramic were researched using 270# diamond wheel both with and without work-piece two-dimension ultrasonic vibration grinding(WTDUVG).By AFM images,the surface topography and the micro structure of the two-dimensional ultrasonic vibration grinding ceramics were especially analyzed.The experimental results indicate that the surface roughness is related to grinding vibration mode and the material removal mechanism.Surface quality of WTDUVG is superior to that of conventional grinding,and it is easy for two-dimensional ultrasonic vibration grinding that material removal mechanism is ductile mode grinding.

  15. Structures and vibrational frequencies of CO adlayers on Rh(111) surface

    Institute of Scientific and Technical Information of China (English)

    XIAO; Haiyan(肖海燕); LAI; Wenzhen(赖文珍); XIE; Daiqian(谢代前); YAN; Guosen(鄢国森)

    2003-01-01

    Density functional theory calculations within the generalized gradient approximation (GGA) have been carried out to study the structural and vibrational properties of carbon monoxide adsorption on Rh(111) surface. The optimized geometries, adsorption energies and vibrational frequencies have been obtained and the preferred binding sites have been determined. The results show that at low coverage CO prefers to adsorb at top site and at high coverage one molecule occupies top site while the two other molecules occupy hcp and fcc hollow sites respectively. The investigation of the vibrational properties of CO chemisorption on Rh(111) shows that the top C-O stretching frequency increases along with the increase of the coverage. The site assignments, optimized geometries and calculated vibrational frequencies are found to be in good agreement with the experimental results.

  16. Exact solution for the vibrations of cylindrical nanoshells considering surface energy effect

    Directory of Open Access Journals (Sweden)

    Hessam Rouhi

    2015-12-01

    Full Text Available It has been revealed that the surface stress effect plays an important role in the mechanical behavior ofstructures (such as bending, buckling and vibration when their dimensions are on the order ofnanometer. In addition, recent advances in nanotechnology have proposed several applications fornanoscale shells in different fields. Hence, in the present article, within the framework of surfaceelasticity theory, the free vibration behavior of simply-supported cylindrical nanoshells with theconsideration of the aforementioned effect is studied using an exact solution method. To this end, first,the governing equations of motion and boundary conditions are obtained by an energy-basedapproach. The surface stress influence is incorporated into the formulation according to the Gurtin-Murdoch theory. The nanoshell is modeled according to the first-order shear deformation shell theory.After that, the free vibration problem is solved through an exact solution approach. To this end, thedimensionless form of governing equations is derived and then solved under the simply-supportedboundary conditions using a Navier-type solution method. Selected numerical results are presentedabout the effects of surface stress and surface material properties on the natural frequencies ofnanoshells with different radii and lengths. The results show that the surface energies significantlyaffect the vibrational behavior of nanoshells with small magnitudes of thickness. Also, it is indicatedthat the natural frequency of the nanoshell is dependent of the surface material properties.

  17. Effect of the free surface and the rigid plane on structural vibration and acoustic radiation

    Institute of Scientific and Technical Information of China (English)

    ZOU Yuanjie; ZHAO Deyou; LI Sheng

    2004-01-01

    The coupled fluid-structure interaction equation is established for bodies in the haft-space fluid domain, especially sitting on the infinite plane, based on the BEM (Boundary Element Method) theory. Then, the natural frequencies, vibration responses and the acoustic radiation for a box are calculated, and the effect of the free surface and the rigid plane is discussed. Finally, several relative factors including the plate thickness, the structure damping and the distance between the body and the infinite plane are studied. The results show that the effect of the free surface and the rigid plane on the structural natural frequencies, vibration responses and the acoustic radiation cannot be ignored.

  18. Comparative study of direct and phase-specific vibrational sum-frequency generation spectroscopy: advantages and limitations.

    Science.gov (United States)

    Pool, Ruben E; Versluis, Jan; Backus, Ellen H G; Bonn, Mischa

    2011-12-29

    As a surface-specific technique, vibrational sum-frequency generation (SFG) is used in a wide range of applications where soft matter or solid interfaces are to be probed on a molecular level through their vibrational modes. In recent years, phase-specific sum-frequency generation (PS-SFG, also known as heterodyne-detected SFG) spectroscopy has been increasingly replacing its predecessor (direct SFG, also known as homodyne SFG) as the experimental technique of choice for characterizing interfacial structure. The technique enables phase sensitive measurements, allowing for the determination of the real and imaginary parts of the interfacial vibrational response function and thereby the unambiguous identification of molecular orientation. This phase-sensitivity requires, however, a complete understanding of the complex optical properties of the sample and of their effect on the signal. These optical properties significantly influence the raw spectral data from which the real and imaginary parts of the second-order susceptibility are retrieved. We show that it is essential to correct the data appropriately to infer the true molecular response. The current study presents a detailed description of the physical contributions to the phase-resolved spectrum, allowing a direct comparison between the phase-resolved spectrum and that obtained using the well-understood direct detection method in a step-by-step data analysis process. In addition to phase sensitivity, PS-SFG has been shown to increase the sensitivity compared to traditional (direct) SFG spectroscopy. We present a quantitative comparison between theoretical limits of the signal-to-noise ratio of both techniques, which shows that for many systems the signal-to-noise ratio is very similar for direct- and phase-specific SFG signals. © 2011 American Chemical Society

  19. Vibrations of tetrahedral Co and Cu clusters on a Cu(111) surface

    Energy Technology Data Exchange (ETDEWEB)

    Borisova, Svetlana D.; Rusina, Galina G. [Institute of Strength Physics and Materials Science SB RAS, pr. Akademichesky 2/4, 634021 Tomsk (Russian Federation); Eremeev, Sergey V. [Institute of Strength Physics and Materials Science SB RAS, pr. Akademichesky 2/4, 634021 Tomsk (Russian Federation); Tomsk State University, pr. Lenina 36, 634050 Tomsk (Russian Federation); Donostia International Physics Center (DIPC), Paseo Manuel de Lardizabal, 4, 20018 San Sebastian/Donostia (Spain); Chulkov, Evgueni V. [Donostia International Physics Center (DIPC), Paseo Manuel de Lardizabal, 4, 20018 San Sebastian/Donostia (Spain); Depto. de Fisica de Materiales and Centro de Fisica de Materiales - CFM (CSIS-UPV/EHU), Facultad de Ciencias Quimicas, Universidad del Pais Vasco/Euskal Herriko Unibertsitatea, Apdo. 1072, 20018 San Sebastian/Donostia (Spain)

    2010-11-15

    Vibrational properties of tetrahedral clusters of Cu and Co on the Cu(111) surface are studied by using interatomic interaction potentials constructed within tight-binding second moment approximation. It was shown that interaction of the Co{sub 4} and Cu{sub 4} clusters with the substrate leads to arising of frustrated translation and frustrated rotation in-plane polarized vibrational modes localized on the cluster atoms. The vibrational modes of the free Cu{sub 4} cluster upon its adsorption on the Cu(111) surface mix with Cu bulk phonons and become almost delocalized. Contrary to that, in the Co{sub 4} cluster on the surface the high frequency modes remain strongly localized and mixed with the nearest neighbor atoms vibrations. The highest frequency vibration of the Co{sub 4} cluster splits due to different interaction with certain groups of nearest neighbor atoms (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  20. Vibrational properties at the ordered metallic surface alloy system Au(110)-1×2-Pd

    Science.gov (United States)

    Kheffache, Sedik; Chadli, Rabah; Khater, Antoine

    2016-06-01

    We present a calculation for the vibrational properties of the ordered surface alloy Au(110)-1×2-Pd on a crystalline substrate of Au. The surface phonon dispersion curves and the local vibrations densities of states (LDOS) are calculated in the harmonic approximation for the system, using the phase field matching theory (PFMT) method and associated real space Green’s functions. In particular, it is shown that the surface alloy presents optic vibrational modes above the Au bulk bands, along the directions of high-symmetry ΓX¯, XS¯, SY¯ and Y Γ¯ of the corresponding two-dimensional Brillouin zone. Measurements of the surface phonon dispersion branches can hence be made by different techniques such as helium atom scattering (HAS) to compare with. The calculated LDOS for Au and Pd atomic sites in the four top surface atomic layers span a wider range of frequencies than those for the individual Au(110) or Pd(110) metallic surfaces. These LDOS provide a spectral signature for the progressive transition from the surface dynamics to that of the Au crystal bulk. Knowledge of these LDOS for the surface alloy can also serve as an input for modeling the diffusion and reaction rates of chemical species at its surface.

  1. Examination and Research of the Surface Topography of Ultrasonic Vibration Honing Nd-Fe-B

    Institute of Scientific and Technical Information of China (English)

    Xi-jing ZHU; Zhi-meng LU; Jian-qing WANG; Quan CHENG

    2010-01-01

    The mechanism of ultrasonic vibration honing Nd-Fe-B has been briefly elaborated after the introduction of the strategic significanoe of processing Nd-Fe-B.Based on the formation principle of Scanning Electrvnic NTicroscope (SFM),and at the exarrnination with the aid of SEM to the ultrasonic vibration honing Nd-Fe-B materials superficial microscopic topography,the paper discusses the new processing mechanism according to the SFM examination picture.The research indicates that as a result of supersonic high frequency vibration,the path of the abrasion extends at the same time,and the supersonic cavitation effect fonts the intense shock-wave,impacting Nd-Fe-B material's internal surface,providing the supersonic energy for the superficial abrasive dust's elimination,which directly explain tat the honing processing efficiency is entranced,and the processing surface rwghness is high.

  2. Ultrasonic pumping of liquids in the two directions of a vertical tube by a vibrating surface

    DEFF Research Database (Denmark)

    Santillan, Arturo Orozco; Cutanda Henriquez, Vicente

    2010-01-01

    It has been reported that it is possible to pump a liquid into the interior of a vertical pipe when its lower end is facing a vibrating plane surface immersed in the liquid. The column of liquid pumped in a thin pipe can be higher than 2 m if the gap between the pipe end and the vibrating...... been to advance in the understanding of both phenomena. By using the Boundary Element Method, the sound pressure field in the liquid is determined. The velocity field, Lagrangian excess pressure, and sound intensity are obtained from the sound pressure. Experimental results show that the amplitude...... of the oscillations of the vibrating horizontal surface determine the direction in which the liquid is pumped. In addition, the size of the gap is also a relevant factor, which has to be significantly small. The carried out numerical simulations show that the Lagrangian excess pressure and the density of linear...

  3. Surface Effects on the Vibration and Buckling of Double-Nanobeam-Systems

    Directory of Open Access Journals (Sweden)

    Dong-Hui Wang

    2011-01-01

    Full Text Available Surface effects on the transverse vibration and axial buckling of double-nanobeam-system (DNBS are examined based on a refined Euler-Bernoulli beam model. For three typical deformation modes of DNBS, we derive the natural frequency and critical axial load accounting for both surface elasticity and residual surface tension, respectively. It is found that surface effects get quite important when the cross-sectional size of beams shrinks to nanometers. No matter for vibration or axial buckling, surface effects are just the same in three deformation modes and usually enhance the natural frequency and critical load. However, the interaction between beams is clearly distinct in different deformation modes. This study might be helpful for the design of nano-optomechanical systems and nanoelectromechanical systems.

  4. Vibration characteristics of aluminum surface subjected to ultrasonic waves and their effect on wetting behavior of solder droplets.

    Science.gov (United States)

    Ma, Lin; Xu, Zhiwu; Zheng, Kun; Yan, Jiuchun; Yang, Shiqin

    2014-03-01

    The vibration characteristics of an aluminum surface subjected to ultrasonic waves were investigated with a combination of numerical simulation and experimental testing. The wetting behavior of solder droplets on the vibrating aluminum surface was also examined. The results show that the vibration pattern of the aluminum surface is inhomogeneous. The amplitude of the aluminum surface exceeds the excitation amplitude in some zones, while the amplitude decreases nearly to zero in other zones. The distribution of the zero-amplitude zones is much less dependent on the strength of the vibration than on the location of the vibration source. The surface of the liquid solder vibrates at an ultrasonic frequency that is higher than the vibration source, and the amplitude of the liquid solder is almost twice that of the aluminum surface. The vibration of the surface of the base metal (liquid solder) correlates with the oxide film removal effect. Significant removal of the oxide film can be achieved within 2s when the amplitude of the aluminum surface is higher than 5.4 μm or when the amplitude of the liquid solder surface is higher than 10.2 μm.

  5. The vibrational and buckling behaviors of piezoelectric nanobeams with surface effects

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Z; Jiang, L Y, E-mail: lyjiang@eng.uwo.ca [Department of Mechanical and Materials Engineering, University of Western Ontario, London, ON, N6A 5B9 (Canada)

    2011-06-17

    In this work, the influence of surface effects, including residual surface stress, surface elasticity and surface piezoelectricity, on the vibrational and buckling behaviors of piezoelectric nanobeams is investigated by using the Euler-Bernoulli beam theory. The surface effects are incorporated by applying the surface piezoelectricity model and the generalized Young-Laplace equations. The results demonstrate that surface effects play a significant role in predicting these behaviors. It is found that the influence of the residual surface stress and the surface piezoelectricity on the resonant frequencies and the critical electric potential for buckling is more prominent than the surface elasticity. The nanobeam boundary conditions are also found to influence the surface effects on these parameters. This study also shows that the resonant frequencies can be tuned by adjusting the applied electrical load. The present study is envisaged to provide useful insights for the design and applications of piezoelectric-beam-based nanodevices.

  6. Evaluation of Breaking Performance in Vibration-Assisted Electrostatic Surface Induction Actuator

    DEFF Research Database (Denmark)

    Nemoto, Takeru; Zsurzsan, Tiberiu-Gabriel; Yamamoto, Akio

    2015-01-01

    This paper evaluates breaking performance of an electrostatic surface induction actuator. The actuator is equipped with piezoelectric vibrator such that the friction between the slider and the stator electrodes can be dramatically reduced by squeeze-film effect. In such an actuator, the friction...... conditions. The result clearly shows the effect of friction change in breaking performance of the actuator....

  7. Probing anharmonic properties of nuclear surface vibration by heavy-ion fusion reactions

    CERN Document Server

    Takigawa, N; Kuyucak, S

    1997-01-01

    Describing fusion reactions between ^{16}O and ^{154}Dy and, between ^{16}O and ^{144}Sm by the $sd-$ and $sdf-$ interacting boson model, we show that heavy-ion fusion reactions are strongly affected by anharmonic properties of nuclear surface vibrations and nuclear shape, and thus provide a powerful method to study details of nuclear structure and dynamics.

  8. Effect of Vibration Training on Anaerobic Power and Quardroceps Surface EMG in Long Jumpers

    Science.gov (United States)

    Liu, Bin; Luo, Jiong

    2015-01-01

    Objective: To explore the anaerobic power and surface EMG (sEMG) of quardrocep muscle in lower extremities after single vibration training intervention. Methods: 8 excellent male long jumpers voluntarily participated in this study. Four intervention modes were devised, including high frequency high amplitude (HFHA,30Hz,6mm), low frequency low…

  9. Theoretical and experimental study of the vibrational excitations in ethane monolayers adsorbed on graphite (0001) surfaces

    DEFF Research Database (Denmark)

    Hansen, Flemming Yssing; Taub, H.

    1987-01-01

    The collective vibrational excitations of two different crystalline monolayer phases of ethane (C2H6) adsorbed on the graphite (0001) surface have been investigated theoretically and experimentally. The monolayer phases studied are the commensurate 7/8 ×4 structure in which the ethane molecules lie...

  10. Water Surface Wave in a Trough with Periodical Topographical Bottom under Vertical Vibration

    Institute of Scientific and Technical Information of China (English)

    HU Yi; MIAO Guo-Qing; WEI Rong-Jue

    2009-01-01

    We investigate the water surface waves in a vertically vibrated long rectangular trough with several identical Plexiglas rectangles lined periodically on the bottom. The band structure is computed theoretically by the method of transfer matrix. Some interesting phenomena, such as the localized wave, especially the solitary-like wave inside the band gap, are observed in the experiments.

  11. Surface quality prediction model of nano-composite ceramics in ultrasonic vibration-assisted ELID mirror grinding

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Bo; Chen, Fan; Jia, Xiao-feng; Zhao, Chong-yang; Wang, Xiao-bo [Henan Polytechnic University, Jiaozuo (China)

    2017-04-15

    Ultrasonic vibration-assisted Electrolytic in-process dressing (ELID) grinding is a highly efficient and highly precise machining method. The surface quality prediction model in ultrasonic vibration-assisted ELID mirror grinding was studied. First, the interaction between grits and workpiece surface was analyzed according to kinematic mechanics, and the surface roughness model was developed. The variations in surface roughness under different parameters was subsequently calculated and analyzed by MATLAB. Results indicate that compared with the ordinary ELID grinding, ultrasonic vibration-assisted ELID grinding is superior, because it has more stable and better surface quality and has an improved range of ductile machining.

  12. Sliding mode control of wind-induced vibrations using fuzzy sliding surface and gain adaptation

    Science.gov (United States)

    Thenozhi, Suresh; Yu, Wen

    2016-04-01

    Although fuzzy/adaptive sliding mode control can reduce the chattering problem in structural vibration control applications, they require the equivalent control and the upper bounds of the system uncertainties. In this paper, we used fuzzy logic to approximate the standard sliding surface and designed a dead-zone adaptive law for tuning the switching gain of the sliding mode control. The stability of the proposed controller is established using Lyapunov stability theory. A six-storey building prototype equipped with an active mass damper has been used to demonstrate the effectiveness of the proposed controller towards the wind-induced vibrations.

  13. Spatial spectrograms of vibrating atomic force microscopy cantilevers coupled to sample surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, Ryan; Raman, Arvind, E-mail: raman@purdue.edu [Birck Nanotechnology Center, 1205 W. State Street, Purdue University, West Lafayette, Indiana 47907 (United States); Proksch, Roger, E-mail: Roger.Proksch@oxinst.com [Asylum Research, 6310 Hollister Ave., Santa Barbara, California 93117 (United States)

    2013-12-23

    Many advanced dynamic Atomic Force Microscopy (AFM) techniques such as contact resonance, force modulation, piezoresponse force microscopy, electrochemical strain microscopy, and AFM infrared spectroscopy exploit the dynamic response of a cantilever in contact with a sample to extract local material properties. Achieving quantitative results in these techniques usually requires the assumption of a certain shape of cantilever vibration. We present a technique that allows in-situ measurements of the vibrational shape of AFM cantilevers coupled to surfaces. This technique opens up unique approaches to nanoscale material property mapping, which are not possible with single point measurements alone.

  14. Theoretical study of potential energy surface and vibrational spectra of ArF2 system

    Institute of Scientific and Technical Information of China (English)

    杨明晖; 谢代前; 鄢国森

    2000-01-01

    An ab initio potential energy surface (PES) of ArF2 system has been obtained by using MP4 calculation with a large basis set including bond functions. There are two local minimums on the PES: one is T-shaped and the other is L-shaped. The L-shaped minimum is the global minimum with a well depth of -119.62 cm- 1 at R = 0.3883nm. The T-shaped minimum has a well depth of -85.93cm -1 at R = 0.3486 nm. A saddle point is found at R = 0.3486 and θ = 61° with the well depth of -61.53 cm-1. The vibrational energy levels have been calculated by using VSCF-CI method. The results show that this PES supports 27 vibrational bound states, and the ground states are two degenerate states assigned to the L-type vibration.

  15. Theoretical study of potential energy surface and vibrational spectra of ArF2 system

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    An ab initio potential energy surface (PES) of ArF2 system has been obtained by using MP4 calculation with a large basis set including bond functions. There are two local minimums on the PES: one is T-shaped and the other is L-shaped. The L-shaped minimum is the global minimum with a well depth of -119.62 cm-1 at R = 0.3883nm. The T-shaped minimum has a well depth of -85.93cm-1 at R = 0.3486 nm. A saddle point is found at R = 0.3486 and q = 61° with the well depth of -61.53 cm-1. The vibrational energy levels have been calculated by using VSCF-CI method. The results show that this PES supports 27 vibrational bound states, and the ground states are two degenerate states assigned to the L-type vibration.

  16. Structural Integrity Assessment Using Laser Measured Surface Vibration

    Science.gov (United States)

    2009-04-01

    structures. Figure 2. (Left) Experimental arrangement for plaster wall assessments at the U.S. Capitol Building showing the SLDV monitoring system, a... termite -like damage to the wood. Broadband SLDV scans were obtained across the available surface of the structure providing dynamic displacement...Figure 2. (Left) Experimental arrangement for plaster wall assessments at the U.S. Capitol Building showing the SLDV monitoring system, a shaker

  17. Vibrational energies for HFCO using a neural network sum of exponentials potential energy surface.

    Science.gov (United States)

    Pradhan, Ekadashi; Brown, Alex

    2016-05-07

    A six-dimensional potential energy surface (PES) for formyl fluoride (HFCO) is fit in a sum-of-products form using neural network exponential fitting functions. The ab initio data upon which the fit is based were computed at the explicitly correlated coupled cluster with single, double, and perturbative triple excitations [CCSD(T)-F12]/cc-pVTZ-F12 level of theory. The PES fit is accurate (RMSE = 10 cm(-1)) up to 10 000 cm(-1) above the zero point energy and covers most of the experimentally measured IR data. The PES is validated by computing vibrational energies for both HFCO and deuterated formyl fluoride (DFCO) using block improved relaxation with the multi-configuration time dependent Hartree approach. The frequencies of the fundamental modes, and all other vibrational states up to 5000 cm(-1) above the zero-point energy, are more accurate than those obtained from the previous MP2-based PES. The vibrational frequencies obtained on the PES are compared to anharmonic frequencies at the MP2/aug-cc-pVTZ and CCSD(T)/aug-cc-pVTZ levels of theory obtained using second-order vibrational perturbation theory. The new PES will be useful for quantum dynamics simulations for both HFCO and DFCO, e.g., studies of intramolecular vibrational redistribution leading to unimolecular dissociation and its laser control.

  18. Sensing site-specific structural characteristics and chirality using vibrational circular dichroism of isotope labeled peptides.

    Science.gov (United States)

    Keiderling, Timothy A

    2017-10-04

    Isotope labeling has a long history in chemistry as a tool for probing structure, offering enhanced sensitivity, or enabling site selection with a wide range of spectroscopic tools. Chirality sensitive methods such as electronic circular dichroism are global structural tools and have intrinsically low resolution. Consequently, they are generally insensitive to modifications to enhance site selectivity. The use of isotope labeling to modify vibrational spectra with unique resolvable frequency shifts can provide useful site-specific sensitivity, and these methods have been recently more widely expanded in biopolymer studies. While the spectral shifts resulting from changes in isotopic mass can provide resolution of modes from specific parts of the molecule and can allow detection of local change in structure with perturbation, these shifts alone do not directly indicate structure or chirality. With vibrational circular dichroism (VCD), the shifted bands and their resultant sign patterns can be used to indicate local conformations in labeled biopolymers, particularly if multiple labels are used and if their coupling is theoretically modeled. This mini-review discusses selected examples of the use of labeling specific amides in peptides to develop local structural insight with VCD spectra. © 2017 Wiley Periodicals, Inc.

  19. Surface effects on the vibration behavior of flexoelectric nanobeams based on nonlocal elasticity theory

    Science.gov (United States)

    Ebrahimi, Farzad; Reza Barati, Mohammad

    2017-01-01

    In this research, vibration characteristics of a flexoelectric nanobeam in contact with Winkler-Pasternak foundation is investigated based on the nonlocal elasticity theory considering surface effects. This nonclassical nanobeam model contains flexoelectric effect to capture coupling of strain gradients and electrical polarizations. Moreover, the nonlocal elasticity theory is employed to study the nonlocal and long-range interactions between the particles. The present model can degenerate into the classical model if the nonlocal parameter, flexoelectric and surface effects are omitted. Hamilton's principle is employed to derive the governing equations and the related boundary conditions which are solved applying a Galerkin-based solution. Natural frequencies are verified with those of previous papers on nanobeams. It is illustrated that flexoelectricity, nonlocality, surface stresses, elastic foundation and boundary conditions affects considerably the vibration frequencies of piezoelectric nanobeams.

  20. Vibration analysis of viscoelastic inhomogeneous nanobeams incorporating surface and thermal effects

    Science.gov (United States)

    Ebrahimi, Farzad; Barati, Mohammad Reza

    2017-01-01

    This article deals with the free vibration investigation of nonlocal strain gradient-based viscoelastic functionally graded (FG) nanobeams on viscoelastic medium considering surface stress effects. Nonlocal strain gradient theory possesses a nonlocal stress field parameter and a length scale parameter for more accurate prediction of mechanical behavior of nanostructures. Surface energy effect is incorporate to the nonlocal strain gradient theory employing Gurtin-Murdoch elasticity theory. Thermo-elastic material properties of nanobeam are graded in thickness direction using power-law distribution. Hamilton's principal is utilized to obtain the governing equations of FG nanobeam embedded in viscoelastic medium. The effects of surface stress, length scale parameter, nonlocal parameter, viscoelastic medium, internal damping constant, thermal loading, power-law index and boundary conditions on vibration frequencies of viscoelastic FGM nanobeams are discussed in detail.

  1. Laser Doppler interferometer for vibration of rotating curved surfaces

    Science.gov (United States)

    Wu, Giin-Yuan; Lee, Chih-Kung; Lin, San; Wakabayashi, Takenori; Ono, K.

    1999-10-01

    With the rapid advancement of today's ultra-high performance mechanical or mechatronic system such as magnetic or optical disk drives, improving metrology capabilities to examine the performance characteristics of these system are growing ever more important. The primary tested studied in this paper is an ultra-high precision ball-bearing spindle that possesses non-repeatable runout of less than 100nm. The metrology tool adopted is laser Doppler interferometer system that has Megahertz bandwidth and nanometer resolutions. Experimental data obtained clearly indicates that measuring vertical runout of a spindle motor is a straightforward process. However, a fundamental effect was identified, where the radial runout data was found to drift upward or downward with time, when using the laser Doppler system to measure the radial runout of ultra-high precision rotational systems whose surface profile is not flat. All of the underlying reasons that cause this undesirable effect were proposed and verified. Approaches that can be adopted to circumvent this apparent limitation on adopting the laser Doppler interferometer systems to measure rotational curved surface were implemented to further extend its application horizon. The experimental data realized and the application experience obtained were shown to further advance our measurement capabilities.

  2. Vibrational states on vicinal surfaces of Al, Ag, Cu and Pd

    Science.gov (United States)

    Sklyadneva, I. Yu.; Rusina, G. G.; Chulkov, E. V.

    1998-10-01

    We present the calculation of vibrational modes and lattice relaxation for the (110), (211), (311), (511), (331) and (221) surfaces of Al, Ag, Cu and Pd. The surface phonon frequencies and polarizations are obtained for relaxed and unrelaxed surfaces using embedded atom model potentials. On all surfaces studied step-localized vibrational modes and surface states localized on terrace atoms are found. It is shown that as the terrace width increases so does the number of surface phonons. It is found that interlayer relaxation leads to a shift in the frequencies of the surface states and to a change in the number and localization. In particular, it may cause the appearance or disappearance of step modes. It is shown that the character of relaxation on vicinal surfaces is determined by the number of atoms on a terrace. A comparison of the results with the available experimental data for the Al(221), Cu(211), and Cu(511) surfaces indicates that there is a good agreement with the experimental data.

  3. Vibrational dynamics of the bifluoride ion. I. Construction of a model potential surface

    Science.gov (United States)

    Epa, V. C.; Choi, J. H.; Klobukowski, M.; Thorson, W. R.

    1990-01-01

    Construction of an extended model potential surface for the bifluoride ion [FHF-] is described, based on ab initio calculations for the free ion at the CID (configuration interaction, double replacement) level with a Huzinaga-Dunning double-zeta basis set. 710 data points were generated, for displacements in the three noncyclic vibrational coordinates exploring the potential surface to a height at least 30 000 cm-1 above its minimum, and giving a realistic account of the dissociation into HF+F-. Analogous calculations were made for HF and F- using the same basis. The predicted hydrogen bond energy (De) is 48.13 kcal/mol, with equilibrium F-F separation Re =4.2905 a.u., in good agreement with other recent calculations. A model potential has been constructed, based on a superposition of Morse potentials associated with each H-F distance plus a fairly structureless correction function expressible as a 36-term least-squares polynomial in the prolate spheroidal coordinates used to describe vibrational displacements. The resulting model surface fits all 710 ab initio data points with an r.m.s. deviation of 65.6 cm-1, and points less than 15 000 cm-1 above the minimum with a deviation of 26.3 cm-1. This surface provides the basis for a series of vibrational dynamics studies on the FHF- system being done in this laboratory.

  4. Vibration reduction in helicopter rotors using an active control surface located on the blade

    Science.gov (United States)

    Millott, T. A.; Friedmann, P. P.

    1992-01-01

    A feasibility study of vibration reduction in a four-bladed helicopter rotor using individual blade control (IBC), which is implemented by an individually controlled aerodynamic surface located on each blade, is presented. For this exploratory study, a simple offset-hinged spring restrained model of the blade is used with fully coupled flap-lag-torsional dynamics for each blade. Deterministic controllers based on local and global system models are implemented to reduce 4/rev hub loads using both an actively controlled aerodynamic surface on each blade as well as conventional IBC, where the complete blade undergoes cyclic pitch change. The effectiveness of the two approaches for simultaneous reduction of the 4/rev hub shears and hub moments is compared. Conventional IBC requires considerably more power to achieve approximately the same level of vibration reduction as that obtained by implementing IBC using an active control surface located on the outboard segment of the blade. The effect of blade torsional flexibility on the vibration reduction effectiveness of the actively controlled surface was also considered and it was found that this parameter has a very substantial influence.

  5. Vibration reduction in helicopter rotors using an active control surface located on the blade

    Science.gov (United States)

    Millott, T. A.; Friedmann, P. P.

    1992-01-01

    A feasibility study of vibration reduction in a four-bladed helicopter rotor using individual blade control (IBC), which is implemented by an individually controlled aerodynamic surface located on each blade, is presented. For this exploratory study, a simple offset-hinged spring restrained model of the blade is used with fully coupled flap-lag-torsional dynamics for each blade. Deterministic controllers based on local and global system models are implemented to reduce 4/rev hub loads using both an actively controlled aerodynamic surface on each blade as well as conventional IBC, where the complete blade undergoes cyclic pitch change. The effectiveness of the two approaches for simultaneous reduction of the 4/rev hub shears and hub moments is compared. Conventional IBC requires considerably more power to achieve approximately the same level of vibration reduction as that obtained by implementing IBC using an active control surface located on the outboard segment of the blade. The effect of blade torsional flexibility on the vibration reduction effectiveness of the actively controlled surface was also considered and it was found that this parameter has a very substantial influence.

  6. The influence of surface effect on vibration behaviors of carbon nanotubes under initial stress

    Science.gov (United States)

    Chen, X.; Fang, C. Q.; Wang, X.

    2017-01-01

    An analytical method is presented to solve the influence of surface effect on non-coaxial resonance of multi-walled carbon nanotubes embedded in matrix utilizing laminated structures model. Due to coupled van der Waals forces between adjacent tubes and surface effect exerted carbon nanotubes, the resonance frequencies and amplitude ratios of multi-walled carbon nanotubes under initial stresses show that the resonant characteristics of the multi-walled carbon nanotubes become complex and the numbers of vibrational modes do not keep increase under identical conditions after considering surface effects. The result obtained can be used as a beneficial reference for investigating the electronic and physical behaviors of carbon nanotubes.

  7. Research on the Surface Micro-configuration in Vibration Cutting Particle Reinforced Metallic Matrix Composites SiC_p/Al

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The cutting performance of particulate reinforced me tallic matrix composites(PRMMCs) SiC p/Al in ultrasonic vibration cutting and c ommon cutting with carbide tools and PCD tools was researched in the paper. Mic rostructure of machined surface was described, the relation between cutting para meters and surface roughness was presented, and characteristic of the surface re mained stress was also presented. Furthermore, wear regularity and abrasion resi stance ability of tools in ultrasonic vibration cut...

  8. Adsorption and Vibrational Study of Folic Acid on Gold Nanopillar Structures Using Surface-enhanced Raman Scattering Spectroscopy

    DEFF Research Database (Denmark)

    Castillo, John J.; Rindzevicius, Tomas; Rozo, Ciro E.

    2015-01-01

    This paper presents a study of adsorption and vibrational features of folic acid, using surface-enhanced Raman scattering (SERS). A gold-capped silicon nanopillar (Au NP) with a height of 600 nm and a width of 120 nm was utilized to study the vibrational features of FA molecules adsorbed on the n...

  9. Ab-initio tensorial electronic friction for molecules on metal surfaces: nonadiabatic vibrational relaxation

    CERN Document Server

    Maurer, Reinhard J; Batista, Victor S; Tully, John C

    2016-01-01

    Molecular adsorbates on metal surfaces exchange energy with substrate phonons and low-lying electron-hole pair excitations. In the limit of weak coupling, electron-hole pair excitations can be seen as exerting frictional forces on adsorbates that enhance energy transfer and facilitate vibrational relaxation or hot-electron mediated chemistry. We have recently reported on the relevance of tensorial properties of electronic friction [Phys. Rev. Lett. 116, 217601 (2016)] in dynamics at surfaces. Here we present the underlying implementation of tensorial electronic friction based on Kohn-Sham Density Functional Theory for condensed phase and cluster systems. Using local atomic-orbital basis sets, we calculate nonadiabatic coupling matrix elements and evaluate the full electronic friction tensor in the classical limit. Our approach is numerically stable and robust as shown by a detailed convergence analysis. We furthermore benchmark the accuracy of our approach by calculation of vibrational relaxation rates and li...

  10. INTRODUCTION: Surface Dynamics, Phonons, Adsorbate Vibrations and Diffusion

    Science.gov (United States)

    Bruch, L. W.

    2004-07-01

    understanding of the underlying factors determining the optical quality of GaInNAs, such as composition, growth and annealing conditions. We are still far from establishing an understanding of the band structure and its dependence on composition. Fundamental electronic interactions such as electron-electron and electron-phonon scattering, dependence of effective mass on composition, strain and orientation, quantum confinement effects, effects of localized nitrogen states on high field transport and on galvanometric properties, and mechanisms for light emission in these materials, are yet to be fully understood. Nature and formation mechanisms of grown-in and processing-induced defects that are important for material quality and device performance are still unknown. Such knowledge is required in order to design strategies to efficiently control and eliminate harmful defects. For many potential applications (such as solar cells, HBTs) it is essential to get more information on the transport properties of dilute nitride materials. The mobility of minority carriers is known to be low in GaInNAs and related material. The experimental values are far from reaching the theoretical ones, due to defects and impurities introduced in the material during the growth. The role of the material inhomogeneities on the lateral carrier transport also needs further investigation. From the device's point of view most attention to date has been focused on the GaInNAs/GaAs system, mainly because of its potential for optoelectronic devices covering the 1.3-1.55 µm data and telecommunications wavelength bands. As is now widely appreciated, these GaAs-compatible structures allow monolithic integration of AlGaAs-based distributed Bragg reflector mirrors (DBRs) for vertical cavity surface-emitting lasers with low temperature sensitivity and compatibility with AlOx-based confinement techniques. In terms of conventional edge-emitting lasers (EELs), the next step is to extend the wavelength range for cw room

  11. Quantification of acute vocal fold epithelial surface damage with increasing time and magnitude doses of vibration exposure.

    Directory of Open Access Journals (Sweden)

    Tsuyoshi Kojima

    Full Text Available Because the vocal folds undergo repeated trauma during continuous cycles of vibration, the epithelium is routinely susceptible to damage during phonation. Excessive and prolonged vibration exposure is considered a significant predisposing factor in the development of vocal fold pathology. The purpose of the present study was to quantify the extent of epithelial surface damage following increased time and magnitude doses of vibration exposure using an in vivo rabbit phonation model. Forty-five New Zealand white breeder rabbits were randomized to nine groups and received varying phonation time-doses (30, 60, or 120 minutes and magnitude-doses (control, modal intensity phonation, or raised intensity phonation of vibration exposure. Scanning electron microscopy and transmission electron microscopy was used to quantify the degree of epithelial surface damage. Results revealed a significant reduction in microprojection density, microprojection height, and depth of the epithelial surface with increasing time and phonation magnitudes doses, signifying increased epithelial surface damage risk with excessive and prolonged vibration exposure. Destruction to the epithelial cell surface may provide significant insight into the disruption of cell function following prolonged vibration exposure. One important goal achieved in the present study was the quantification of epithelial surface damage using objective imaging criteria. These data provide an important foundation for future studies of long-term tissue recovery from excessive and prolonged vibration exposure.

  12. ELECTRIC ARC WELDING DEPOSITION OF METALLIC SURFACES BY VIBRATING ELECTRODE IN PROTECTIVE GAS MEDIUM

    OpenAIRE

    N. Spiridonov; A. Кudina; V. Кurash

    2013-01-01

    The paper presents methods for obtaining qualitative metallic surfaces by electric arc welding deposition while using consumable electrode in a protective gas medium and executing regularized drop transfer of electrode metal. The drop transfer efficiency of electrode metal and productivity of welding deposition are significantly increased due to excitation of lateral vibrations in the consumable electrode with preset amplitude. The paper describes a method and a device for welding deposition ...

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

    Institute of Scientific and Technical Information of China (English)

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

    2001-01-01

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

  14. Model for continuously scanning ultrasound vibrometer sensing displacements of randomly rough vibrating surfaces.

    Science.gov (United States)

    Ratilal, Purnima; Andrews, Mark; Donabed, Ninos; Galinde, Ameya; Rappaport, Carey; Fenneman, Douglas

    2007-02-01

    An analytic model is developed for the time-dependent ultrasound field reflected off a randomly rough vibrating surface for a continuously scanning ultrasound vibrometer system in bistatic configuration. Kirchhoff's approximation to Green's theorem is applied to model the three-dimensional scattering interaction of the ultrasound wave field with the vibrating rough surface. The model incorporates the beam patterns of both the transmitting and receiving ultrasound transducers and the statistical properties of the rough surface. Two methods are applied to the ultrasound system for estimating displacement and velocity amplitudes of an oscillating surface: incoherent Doppler shift spectra and coherent interferometry. Motion of the vibrometer over the randomly rough surface leads to time-dependent scattering noise that causes a randomization of the received signal spectrum. Simulations with the model indicate that surface displacement and velocity estimation are highly dependent upon the scan velocity and projected wavelength of the ultrasound vibrometer relative to the roughness height standard deviation and correlation length scales of the rough surface. The model is applied to determine limiting scan speeds for ultrasound vibrometer measuring ground displacements arising from acoustic or seismic excitation to be used in acoustic landmine confirmation sensing.

  15. Receptivity of the Boundary Layer to Vibrations of the Wing Surface

    Science.gov (United States)

    Bernots, Tomass; Ruban, Anatoly; Pryce, David; Laminar Flow Control UK Group Team

    2014-11-01

    In this work we study generation of Tollmien-Schlichting (T-S) waves in the boundary layer due to elastic vibrations of the wing surface. The flow is investigated based on the asymptotic analysis of the Navier-Stokes equations at large values of the Reynolds number. It is assumed that in the spectrum of the wing vibrations there is a harmonic which comes in resonance with the T-S wave on the lower branch of the stability curve. It was found that the vibrations of the wing surface produce pressure perturbations in the flow outside the boundary layer which can be calculated with the help of the piston theory. As the pressure perturbations penetrate into the boundary layer, a Stokes layer forms on the wing surface which appears to be influenced significantly by the compressibility of the flow, and is incapable of producing the T-S waves. The situation changes when the Stokes layer encounters an roughness; near which the flow is described using the triple-deck theory. The solution of the triple-deck problem can be found in an analytic form. Our main concern is with the flow behaviour downstream of the roughness and, in particular, with the amplitude of the generated Tollmien-Schlichting waves. This research was performed in the Laminar Flow Control Centre (LFC-UK) at Imperial College London. The centre is supported by EPSRC, Airbus UK and EADS Innovation Works.

  16. Determining the location of buried plastic water pipes from measurements of ground surface vibration

    Science.gov (United States)

    Muggleton, J. M.; Brennan, M. J.; Gao, Y.

    2011-09-01

    ‘Mapping the Underworld' is a UK-based project, which aims to create a multi-sensor device that combines complementary technologies for remote buried utility service detection and location. One of the technologies to be incorporated in the device is low-frequency vibro-acoustics, and techniques for detecting buried infrastructure, in particular plastic water pipes, are being investigated. One of the proposed techniques involves excitation of the pipe at some known location with concurrent vibrational mapping of the ground surface in order to infer the location of the remainder of the pipe. In this paper, measurements made on a dedicated pipe rig are reported. Frequency response measurements relating vibrational velocity on the ground to the input excitation were acquired. Contour plots of the unwrapped phase revealed the location of the pipe to within 0.1-0.2 m. Magnitude contour plots revealed the excitation point and also the location of the pipe end. By examining the unwrapped phase gradients along a line above the pipe, it was possible to identify the wave-type within the pipe responsible for the ground surface vibration. Furthermore, changes in the ground surface phase speed computed using this method enabled the location of the end of the pipe to be confirmed.

  17. Influence of thermal and surface effects on vibration behavior of nonlocal rotating Timoshenko nanobeam

    Science.gov (United States)

    Ghadiri, Majid; Shafiei, Navvab; Akbarshahi, Amir

    2016-07-01

    This paper is proposed to study the free vibration of a rotating Timoshenko nanobeam based on the nonlocal theory considering thermal and surface elasticity effects. The governing equations and the related boundary conditions are derived using the Hamilton's principle. In order to solve the problem, generalized differential quadrature method is applied to discretize the governing differential equations corresponding to clamped-simply and clamped-free boundary conditions. In this article, the influences of some parameters such as nonlocal parameter, angular velocity, thickness of the nanobeam, and thermal and surface elasticity effects on the free vibration of the rotating nanobeam are investigated, and the results are compared for different boundary conditions. The results show that the surface effect and the nonlocal parameter and the temperature changes have significant roles, and they should not be ignored in the vibrational study of rotating nanobeams. Also, the angular velocity and the hub radius have more significant roles than temperature change effects on the nondimensional frequency. It is found that the nonlocal parameter behavior and the temperature change behavior on the frequency are different in the first mode for the rotating cantilever nanobeam.

  18. Carbonyl iron powder surface modification of magnetorheological elastomers for vibration absorbing application

    Science.gov (United States)

    Chen, Dong; Yu, Miao; Zhu, Mi; Qi, Song; Fu, Jie

    2016-11-01

    With excellent characteristic of magnetic-control stiffness, magnetorheological elastomer (MRE) is well suited as a spring element of vibration absorber. To improve the vibration attenuation performance of MRE vibration absorbers, this paper expects to improve the mechanical strength and reduce the loss factor of MRE by interface modification. The surface of carbonyl iron powder (CIP) was modified with silica coating by a simple and convenient approach. Several MRE samples, with different proportions of modified CIPs were fabricated under a constant magnetic field. The morphology and composition of modified CIP were characterized by scanning electron microscope and Fourier transform infrared spectra. The results indicated that the modified CIPs were coated with uniform and continuous silica, which can make a better combination between particle and matrix. The tensile strength, magnetorheological properties and the damping properties of the MRE samples were tested by material testing machine and rheometer. The experimental results demonstrated that the loss factor of the MRE which incorporated with modified CIPs decreased markedly, and the tensile strength of such material has been much improved, at the same time this kind of MRE kept high MR effect. It is expected that this MRE material will meet the requirements of vibration absorber.

  19. Simulation of cross-flow-induced vibration of tube bundle by surface vorticity method

    Institute of Scientific and Technical Information of China (English)

    Fenghao WANG; Gedong JIANG; Jong Zhang Lin

    2008-01-01

    A fluid-structure interaction model based on Surface Vorticity Method (SVM) was used to study flow-induced vibrations of tube bundles in medium space ratio. The flow-induced vibrations of four tubes in a rotated square and a staggered tube bundle in three-row and five-column arrangements were simulated in the high sub-critical Reynolds number (Re) range. The results on fluid forces, tube responses and vorticity maps were pre-sented. The vorticity maps of the four rotated-square tubes changed dramatically when the rigid tubes were replaced by the flexible tubes. From the vorticity maps and vibration responses of the staggered tube bundle of different structural parameters, it was found that with the decrease of tube natural frequency, the maximal vibration response moved from the third row to the first. The results also showed that when more flexible tubes are used, the flow pattern changed drastically and the fluid-structure interaction imposed a dominant impact on the flow.

  20. Can Internal Conversion BE Controlled by Mode-Specific Vibrational Excitation in Polyatomic Molecules

    Science.gov (United States)

    Portnov, Alexander; Epshtein, Michael; Bar, Ilana

    2017-06-01

    Nonadiabatic processes, dominated by dynamic passage of reactive fluxes through conical intersections (CIs) are considered to be appealing means for manipulating reaction paths. One approach that is considered to be effective in controlling the course of dissociation processes is the selective excitation of vibrational modes containing a considerable component of motion. Here, we have chosen to study the predissociation of the model test molecule, methylamine and its deuterated isotopologues, excited to well-characterized quantum states on the first excited electronic state, S_{1}, by following the N-H(D) bond fission dynamics through sensitive H(D) photofragment probing. The branching ratios between slow and fast H(D) photofragments, the internal energies of their counter radical photofragments and the anisotropy parameters for fast H photofragments, confirm correlated anomalies for predissociation initiated from specific rovibronic states, reflecting the existence of a dynamic resonance in each molecule. This resonance strongly depends on the energy of the initially excited rovibronic states, the evolving vibrational mode on the repulsive S_{1} part during N-H(D) bond elongation, and the manipulated passage through the CI that leads to radicals excited with C-N-H(D) bending and preferential perpendicular bond breaking, relative to the photolyzing laser polarization, in molecules containing the NH_{2} group. The indicated resonance plays an important role in the bifurcation dynamics at the CI and can be foreseen to exist in other photoinitiated processes and to control their outcome.

  1. The dynamic specification of surfaces and boundaries.

    Science.gov (United States)

    Cunningham, D W; Shipley, T F; Kellman, P J

    1998-01-01

    Sequential changes in small separated texture elements can produce perception of a moving form with continuous boundaries. This process of spatiotemporal boundary formation may exist to provide a robust means of detecting moving objects that occlude more distant textured surfaces. Whereas most research on spatiotemporal boundary formation has been focused on boundary and shape perception, two experiments are reported here on the perception of surface qualities in spatiotemporal boundary formation. In experiment 1 a free-report procedure was used to investigate whether surface perception can be determined by dynamic information alone, apart from static spatial differences. Results showed that dynamic information was sufficient to determine the appearance of a surface. This dynamic information may play an important role in other aspects of perception. In experiment 2, it was shown that dynamically specifying an extended, opaque surface facilitated edge perception. Implications for the relation of boundary and surface perception and for theories of perceptual transparency are discussed.

  2. Mode-specific energy absorption by solvent molecules during CO2 vibrational cooling.

    Science.gov (United States)

    Kandratsenka, Alexander; Schroeder, Jörg; Schwarzer, Dirk; Vikhrenko, Vyacheslav S

    2007-04-14

    Non-equilibrium molecular dynamics (NEMD) simulations of energy transfer from vibrationally excited CO(2) to CCl(4) and CH(2)Cl(2) solvent molecules are performed to identify the efficiency of different energy pathways into the solvent bath. Studying in detail the work performed by the vibrationally excited solute on the different solvent degrees of freedom, it is shown that vibration-to-vibration (V-V) processes are strongly dominant and controlled by those accepting modes which are close in frequency to the CO(2) bend and symmetric stretch vibration.

  3. Applicability of Density Functional Theory in Reproducing Accurate Vibrational Spectra of Surface Bound Species

    Energy Technology Data Exchange (ETDEWEB)

    Matanovic, Ivana; Atanassov, Plamen; Kiefer, Boris; Garzon, Fernando; Henson, Neil J.

    2014-10-05

    The structural equilibrium parameters, the adsorption energies, and the vibrational frequencies of the nitrogen molecule and the hydrogen atom adsorbed on the (111) surface of rhodium have been investigated using different generalized-gradient approximation (GGA), nonlocal correlation, meta-GGA, and hybrid functionals, namely, Perdew, Burke, and Ernzerhof (PBE), Revised-RPBE, vdW-DF, Tao, Perdew, Staroverov, and Scuseria functional (TPSS), and Heyd, Scuseria, and Ernzerhof (HSE06) functional in the plane wave formalism. Among the five tested functionals, nonlocal vdW-DF and meta-GGA TPSS functionals are most successful in describing energetics of dinitrogen physisorption to the Rh(111) surface, while the PBE functional provides the correct chemisorption energy for the hydrogen atom. It was also found that TPSS functional produces the best vibrational spectra of the nitrogen molecule and the hydrogen atom on rhodium within the harmonic formalism with the error of 22.62 and 21.1% for the NAN stretching and RhAH stretching frequency. Thus, TPSS functional was proposed as a method of choice for obtaining vibrational spectra of low weight adsorbates on metallic surfaces within the harmonic approximation. At the anharmonic level, by decoupling the RhAH and NAN stretching modes from the bulk phonons and by solving one- and two-dimensional Schr€odinger equation associated with the RhAH, RhAN, and NAN potential energy we calculated the anharmonic correction for NAN and RhAH stretching modes as 231 cm21 and 277 cm21 at PBE level. Anharmonic vibrational frequencies calculated with the use of the hybrid HSE06 function are in best agreement with available experiments.

  4. Vibrational properties of Cu(100)-c(2×2)-Pd surface and subsurface alloys

    Science.gov (United States)

    Sklyadneva, I. Yu.; Rusina, G. G.; Chulkov, E. V.

    2003-07-01

    Using interaction potentials from the embedded-atom method we investigated the structural and vibrational properties of a Cu(100)-c(2×2)-Pd surface alloy and an underlayer c(2×2) alloy with a mixed CuPd second layer. The calculated surface phonon frequencies are in agreement with the experimental values obtained by electron energy-loss spectroscopy. From the calculated local phonon densities of states we find that surface effects are most pronounced in the first two layers for both systems studied. The results also indicate a very strong Pd-Cu bonding accompanied by a weaker bonding of the Cu surface atoms to their nearest neighbors. This has considerable influence on the surface phonon frequencies.

  5. Spreading and atomization of droplets on a vibrating surface in a standing pressure field

    Science.gov (United States)

    Deepu, P.; Basu, Saptarshi; Saha, Abhishek; Kumar, Ranganathan

    2012-10-01

    We report the first observation and analytical model of deformation and spreading of droplets on a vibrating surface under the influence of an ultrasonic standing pressure field. The standing wave allows the droplet to spread, and the spreading rate varies inversely with viscosity. In low viscosity droplets, the synergistic effect of radial acoustic force and the transducer surface acceleration also leads to capillary waves. These unstable capillary modes grow to cause ultimate disintegration into daughter droplets. We find that using nanosuspensions, spreading and disintegration can be prevented by suppressing the development of capillary modes and subsequent break-up.

  6. Hemispheric specificity for proprioception: Postural control of standing following right or left hemisphere damage during ankle tendon vibration.

    Science.gov (United States)

    Duclos, Noémie C; Maynard, Luc; Abbas, Djawad; Mesure, Serge

    2015-11-02

    Right brain damage (RBD) following stroke often causes significant postural instability. In standing (without vision), patients with RBD are more unstable than those with left brain damage (LBD). We hypothesised that this postural instability would relate to the cortical integration of proprioceptive afferents. The aim of this study was to use tendon vibration to investigate whether these changes were specific to the paretic or non-paretic limbs. 14 LBD, 12 RBD patients and 20 healthy subjects were included. Displacement of the Centre of Pressure (CoP) was recorded during quiet standing, then during 3 vibration conditions (80 Hz - 20s): paretic limb, non-paretic limb (left and right limbs for control subjects) and bilateral. Vibration was applied separately to the peroneal and Achilles tendons. Mean antero-posterior position of the CoP, variability and velocity were calculated before (4s), during and after (24s) vibration. For all parameters, the strongest perturbation was during Achilles vibrations. The Achilles non-paretic condition induced a larger backward displacement than the Achilles paretic condition. This condition caused specific behaviour on the velocity: the LBD group was perturbed at the onset of the vibrations, but gradually recovered their stability; the RBD group was significantly perturbed thereafter. After bilateral Achilles vibration, RBD patients required the most time to restore initial posture. The reduction in use of information from the paretic limb may be a central strategy to deal with risk-of-fall situations such as during Achilles vibration. The postural behaviour is profoundly altered by lesions of the right hemisphere when proprioception is perturbed.

  7. A shear wave ground surface vibration technique for the detection of buried pipes

    Science.gov (United States)

    Muggleton, J. M.; Papandreou, B.

    2014-07-01

    A major UK initiative, entitled 'Mapping the Underworld' aims to develop and prove the efficacy of a multi-sensor device for accurate remote buried utility service detection, location and, where possible, identification. One of the technologies to be incorporated in the device is low-frequency vibro-acoustics; the application of this technology for detecting buried infrastructure, in particular pipes, is currently being investigated. Here, a shear wave ground vibration technique for detecting buried pipes is described. For this technique, shear waves are generated at the ground surface, and the resulting ground surface vibrations measured. Time-extended signals are employed to generate the illuminating wave. Generalized cross-correlation functions between the measured ground velocities and a reference measurement adjacent to the excitation are calculated and summed using a stacking method to generate a cross-sectional image of the ground. To mitigate the effects of other potential sources of vibration in the vicinity, the excitation signal can be used as an additional reference when calculating the cross-correlation functions. Measurements have been made at two live test sites to detect a range of buried pipes. Successful detection of the pipes was achieved, with the use of the additional reference signal proving beneficial in the noisier of the two environments.

  8. Tactile Perception and Friction-Induced Vibrations: Discrimination of Similarly Patterned Wood-Like Surfaces.

    Science.gov (United States)

    Dacleu Ndengue, Jessica; Cesini, B Ilaria; Faucheu, C Jenny; Chatelet, D Eric; Zahouani, E Hassan; Delafosse, F David; Massi, G Francesco

    2016-12-22

    The tactile perception of a surface texture is mediated by factors such as material, topography and vibrations induced by the sliding contact. In this paper, sensory characterizations are developed together with topographical and tribo-tactile characterizations to relate perceived features with objective measurements of tribological and dynamic signals. Two sets of surface samples are used in this study: the first set is made of a commercial floor covering tiles that aim at counter-typing natural wood flooring, with both a visual and a tactile texture mimicking wood. A second set is custom-made by replicating the first set using a plain purple polyurethane resin. The comparison between tribo-tactile signals and sensory analysis allowed the identification of objective indices for textures with slight topographical differences. Even though the topography of the replicated samples is the same as their corresponding commercial products, the fact that the material is different, induces differences in the contact and vibrational parameters. This in turn modifies the discrimination performances during the sensory experiment. Tactile characteristics collected during sensory procedures are found to be in agreement with objective indices such as friction coefficients and induced vibrations.

  9. Vibrations and potential energy surfaces (with Argonne V18) of4He and3He

    Science.gov (United States)

    Fortunato, Lorenzo

    2017-07-01

    A potential energy surface is constructed for3,4He with the two-body Argonne V18 potential. The minimization suggests a semi-rigid asymmetric top structure for4He, where the appropriate pointgroup symmetry is C 2. We calculate the Hessian matrix, determining the 6 normal modes of vibration (in the range 300-700 MeV). The breathing mode is found to lie at too high an energy to be observable and the nature of the {0}2+ excited states of the alpha particle at 20 MeV should probably be sought elsewhere. Similar investigations have been carried out for the A=3 system, finding a planar Cs configuration (scalene triangle) and three excited vibrational states (in the range 600-1900 MeV).

  10. Remote vibration measurement: a wireless passive surface acoustic wave resonator fast probing strategy.

    Science.gov (United States)

    Friedt, J-M; Droit, C; Ballandras, S; Alzuaga, S; Martin, G; Sandoz, P

    2012-05-01

    Surface acoustic wave (SAW) resonators can advantageously operate as passive sensors which can be interrogated through a wireless link. Amongst the practical applications of such devices, structural health monitoring through stress measurement and more generally vibration characteristics of mechanical structures benefit from the ability to bury such sensors within the considered structure (wireless and battery-less). However, measurement bandwidth becomes a significant challenge when measuring wideband vibration characteristics of mechanical structures. A fast SAW resonator measurement scheme is demonstrated here. The measurement bandwidth is limited by the physical settling time of the resonator (Q/π periods), requiring only two probe pulses through a monostatic RADAR-like electronic setup to identify the sensor resonance frequency and hence stress on a resonator acting as a strain gauge. A measurement update rate of 4800 Hz using a high quality factor SAW resonator operating in the 434 MHz Industrial, Scientific and Medical band is experimentally demonstrated.

  11. Effects of surface topography and vibrations on wetting: Superhydrophobicity, icephobicity and corrosion resistance

    Science.gov (United States)

    Ramachandran, Rahul

    Concrete and metallic materials are widely used in construction and water industry. The interaction of both these materials with water and ice (or snow) produces undesirable results and is therefore of interest. Water that gets absorbed into the pores of dry concrete expands on freezing and can lead to crack formation. Also, the ice accretion on concrete surfaces such as roadways can have disastrous consequence. Metallic components used in the water industry undergo corrosion due to contact with aqueous corrosive solutions. Therefore, it is desirable to make concrete water/ice-repellent, and to make metallic surfaces corrosion-resistant. Recent advances in micro/nanotechnology have made it possible to design functional micro/nanostructured surfaces with micro/nanotopography providing low adhesion. Some examples of such surfaces are superhydrophobic surfaces, which are extremely water repellent, and icephobic surfaces, which have low ice adhesion, repel incoming water droplets before freezing, or delay ice nucleation. This dissertation investigates the effects of surface micro/nanotopography and small amplitude fast vibrations on the wetting and adhesion of concrete with the goal of producing hydrophobic and icephobic concrete, and on the wetting of metallic surfaces to prevent corrosion. The relationship between surface micro/nanotopography and small fast vibrations is established using the method of separation of motions. Both these small scale effects can be substituted by an effective force or energy. The structure-property relationships in materials and surfaces are established. Both vibrations as well as surface micro/nanopatterns can affect wetting properties such as contact angle and surface free energy. Hydrophobic engineered cementitious composite samples are produced by controlling their surface topography and surface free energy. The surface topography is controlled by varying the concrete mixture composition. The surface free energy of concrete is

  12. Identification of surface species by vibrational normal mode analysis. A DFT study

    Science.gov (United States)

    Zhao, Zhi-Jian; Genest, Alexander; Rösch, Notker

    2017-10-01

    Infrared spectroscopy is an important experimental tool for identifying molecular species adsorbed on a metal surface that can be used in situ. Often vibrational modes in such IR spectra of surface species are assigned and identified by comparison with vibrational spectra of related (molecular) compounds of known structure, e. g., an organometallic cluster analogue. To check the validity of this strategy, we carried out a computational study where we compared the normal modes of three C2Hx species (x = 3, 4) in two types of systems, as adsorbates on the Pt(111) surface and as ligands in an organometallic cluster compound. The results of our DFT calculations reproduce the experimental observed frequencies with deviations of at most 50 cm-1. However, the frequencies of the C2Hx species in both types of systems have to be interpreted with due caution if the coordination mode is unknown. The comparative identification strategy works satisfactorily when the coordination mode of the molecular species (ethylidyne) is similar on the surface and in the metal cluster. However, large shifts are encountered when the molecular species (vinyl) exhibits different coordination modes on both types of substrates.

  13. Surface and thermal effects on vibration of embedded alumina nanobeams based on novel Timoshenko beam model

    Institute of Scientific and Technical Information of China (English)

    B AMIRIAN; R HOSSEINI-ARA; H MOOSAVI

    2014-01-01

    This paper deals with the free vibration analysis of circular alumina (Al2O3) nanobeams in the presence of surface and thermal effects resting on a Pasternak foun-dation. The system of motion equations is derived using Hamilton’s principle under the assumptions of the classical Timoshenko beam theory. The effects of the transverse shear deformation and rotary inertia are also considered within the framework of the mentioned theory. The separation of variables approach is employed to discretize the governing equa-tions which are then solved by an analytical method to obtain the natural frequencies of the alumina nanobeams. The results show that the surface effects lead to an increase in the natural frequency of nanobeams as compared with the classical Timoshenko beam model. In addition, for nanobeams with large diameters, the surface effects may increase the natural frequencies by increasing the thermal effects. Moreover, with regard to the Pasternak elastic foundation, the natural frequencies are increased slightly. The results of the present model are compared with the literature, showing that the present model can capture correctly the surface effects in thermal vibration of nanobeams.

  14. Engineering and Characterization of Peptides and Proteins at Surfaces and Interfaces: A Case Study in Surface-Sensitive Vibrational Spectroscopy.

    Science.gov (United States)

    Ding, Bei; Jasensky, Joshua; Li, Yaoxin; Chen, Zhan

    2016-06-21

    Understanding molecular structures of interfacial peptides and proteins impacts many research fields by guiding the advancement of biocompatible materials, new and improved marine antifouling coatings, ultrasensitive and highly specific biosensors and biochips, therapies for diseases related to protein amyloid formation, and knowledge on mechanisms for various membrane proteins and their interactions with ligands. Developing methods for measuring such unique systems, as well as elucidating the structure and function relationship of such biomolecules, has been the goal of our lab at the University of Michigan. We have made substantial progress to develop sum frequency generation (SFG) vibrational spectroscopy into a powerful technique to study interfacial peptides and proteins, which lays a foundation to obtain unique and valuable insights when using SFG to probe various biologically relevant systems at the solid/liquid interface in situ in real time. One highlighting feature of this Account is the demonstration of the power of combining SFG with other techniques and methods such as ATR-FTIR, surface engineering, MD simulation, liquid crystal sensing, and isotope labeling in order to study peptides and proteins at interfaces. It is necessary to emphasize that SFG plays a major role in these studies, while other techniques and methods are supplemental. The central role of SFG is to provide critical information on interfacial peptide and protein structure (e.g., conformation and orientation) in order to elucidate how surface engineering (e.g., to vary the structure) can ultimately affect surface function (e.g., to optimize the activity). This Account focuses on the most significant recent progress in research on interfacial peptides and proteins carried out by our group including (1) the development of SFG analysis methods to determine orientations of regular as well as disrupted secondary structures, and the successful demonstration and application of an isotope

  15. Nanoscopic vibrations of bacteria with different cell-wall properties adhering to surfaces under flow and static conditions.

    Science.gov (United States)

    Song, Lei; Sjollema, Jelmer; Sharma, Prashant K; Kaper, Hans J; van der Mei, Henny C; Busscher, Henk J

    2014-08-26

    Bacteria adhering to surfaces demonstrate random, nanoscopic vibrations around their equilibrium positions. This paper compares vibrational amplitudes of bacteria adhering to glass. Spring constants of the bond are derived from vibrational amplitudes and related to the electrophoretic softness of the cell surfaces and dissipation shifts measured upon bacterial adhesion in a quartz-crystal-microbalance (QCM-D). Experiments were conducted with six bacterial strains with pairwise differences in cell surface characteristics. Vibrational amplitudes were highest in low ionic strength suspensions. Under fluid flow, vibrational amplitudes were lower in the direction of flow than perpendicular to it because stretching of cell surface polymers in the direction of flow causes stiffening of the polyelectrolyte network surrounding a bacterium. Under static conditions (0.57 mM), vibrational amplitudes of fibrillated Streptococcus salivarius HB7 (145 nm) were higher than that of a bald mutant HB-C12 (76 nm). Amplitudes of moderately extracellular polymeric substance (EPS) producing Staphylococcus epidermidis ATCC35983 (47 nm) were more than twice the amplitudes of strongly EPS producing S. epidermidis ATCC35984 (21 nm). No differences were found between Staphylococcus aureus strains differing in membrane cross-linking. High vibrational amplitudes corresponded with low dissipation shifts in QCM-D. In streptococci, the polyelectrolyte network surrounding a bacterium is formed by fibrillar surface appendages and spring constants derived from vibrational amplitudes decreased with increasing fibrillar density. In staphylococci, EPS constitutes the main network component, and larger amounts of EPS yielded higher spring constants. Spring constants increased with increasing ionic strength and strains with smaller electrophoretically derived bacterial cell surface softnesses possessed the highest spring constants.

  16. Adsorption and Vibration of Cl Atoms on Ni Low-index Surfaces

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The 5-parameter Morse potential(5-MP) of the interactions between Cl atoms and Ni surfaces was constructed. The adsorption and diffusion of Cl atoms on Ni low index-surfaces were investigated with 5-MP in detail. All the critical characteristics of the system, such as adsorption site, adsorption geometry, binding energy, eigenvalues for vibration, etc. were obtained. The calculated results show that chlorine atoms are likely to be adsorbed on the high symmetry sites. Cl atoms locate on the four-fold hollow sites of the intact Ni(100) surface, while they tend to occupy three-fold sites on the Ni(111) surface. The four-fold hollow sites are the most stable adsorption sites on the Ni(110) surface for Cl, although the three-fold sites and the long-bridge sites are stable adsorption sites on the Ni(110) surface for the atoms of the first and second periods. For the Cl-Ni surface adsorption system, the surface binding energy of a Cl atom is relevant to the coarse degree of the cluster surface, and the binding energies have an order of Ni(111)<Ni(100)<Ni(110).

  17. Mode pattern of internal flow in a water droplet on a vibrating hydrophobic surface.

    Science.gov (United States)

    Kim, Hun; Lim, Hee-Chang

    2015-06-01

    The objective of this study is to understand the mode pattern of the internal flow in a water droplet placed on a hydrophobic surface that periodically and vertically vibrates. As a result, a water droplet on a vibrating hydrophobic surface has a typical shape that depends on each resonance mode, and, additionally, we observed a diversified lobe size and internal flows in the water droplet. The size of each lobe at the resonance frequency was relatively greater than that at the neighboring frequencies, and the internal flow of the nth order mode was also observed in the flow visualization. In general, large symmetrical flow streams were generated along the vertical axis in each mode, with a large circulating movement from the bottom to the top, and then to the triple contact line along the droplet surface. In contrast, modes 2 and 4 generated a Y-shaped flow pattern, in which the flow moved to the node point in the lower part of the droplet, but modes 6 and 8 had similar patterns, with only a little difference. In addition, as a result of the PIV measurement, while the flow velocity of mode 4 was faster than that of model 2, those of modes 6 and 8 were almost similar.

  18. Ab initio tensorial electronic friction for molecules on metal surfaces: Nonadiabatic vibrational relaxation

    Science.gov (United States)

    Maurer, Reinhard J.; Askerka, Mikhail; Batista, Victor S.; Tully, John C.

    2016-09-01

    Molecular adsorbates on metal surfaces exchange energy with substrate phonons and low-lying electron-hole pair excitations. In the limit of weak coupling, electron-hole pair excitations can be seen as exerting frictional forces on adsorbates that enhance energy transfer and facilitate vibrational relaxation or hot-electron-mediated chemistry. We have recently reported on the relevance of tensorial properties of electronic friction [M. Askerka et al., Phys. Rev. Lett. 116, 217601 (2016), 10.1103/PhysRevLett.116.217601] in dynamics at surfaces. Here we present the underlying implementation of tensorial electronic friction based on Kohn-Sham density functional theory for condensed phase and cluster systems. Using local atomic-orbital basis sets, we calculate nonadiabatic coupling matrix elements and evaluate the full electronic friction tensor in the Markov limit. Our approach is numerically stable and robust, as shown by a detailed convergence analysis. We furthermore benchmark the accuracy of our approach by calculation of vibrational relaxation rates and lifetimes for a number of diatomic molecules at metal surfaces. We find friction-induced mode-coupling between neighboring CO adsorbates on Cu(100) in a c (2 ×2 ) overlayer to be important for understanding experimental findings.

  19. Motion of liquid drops on surfaces induced by asymmetric vibration: role of contact angle hysteresis.

    Science.gov (United States)

    Mettu, Srinivas; Chaudhury, Manoj K

    2011-08-16

    Hysteresis of wetting, like the Coulombic friction at solid/solid interface, impedes the motion of a liquid drop on a surface when subjected to an external field. Here, we present a counterintuitive example, where some amount of hysteresis enables a drop to move on a surface when it is subjected to a periodic but asymmetric vibration. Experiments show that a surface either with a negligible or high hysteresis is not conducive to any drop motion. Some finite hysteresis of contact angle is needed to break the periodic symmetry of the forcing function for the drift to occur. These experimental results are consistent with simulations, in which a drop is approximated as a linear harmonic oscillator. The experiment also sheds light on the effect of the drop size on flow reversal, where drops of different sizes move in opposite directions due to the difference in the phase of the oscillation of their center of mass.

  20. Optical multi-frequency swept sensing for wide-field vibration measurement of interior surfaces in biological tissue

    Science.gov (United States)

    Choi, S.; Nin, F.; Hibino, H.; Suzuki, T.

    2015-12-01

    Multifrequency sensing technique adopting the wide field heterodyne detection technique is demonstrated for interior surface vibration measurements in thick biological tissue. These arrangements allow obtaining not only 3D tomographic images but also various vibration parameters such as spatial amplitude, phase, and frequency, with high temporal and transverse resolutions over a wide field. The axial resolution and the accuracy of vibration amplitude measurement were estimated to be 2.5 μm and 3 nm, respectively. This wide-field tomographic sensing method can be applied for measuring microdynamics of a variety of biological samples, thus contributing to the progress in life sciences research.

  1. Vibrational Spectra and Potential Energy Surface for Electronic Ground State of Jet-Cooled Molecule S2O

    Institute of Scientific and Technical Information of China (English)

    WANG Xiao-Yan; DING Shi-Liang

    2004-01-01

    The vibration states of transition molecule S2O, including both bending and stretching vibrations, are studied in the framework of dynamical symmetry groups U1(4) U2(4). We get all the vibration spectra of S2O by fitting 22 spectra data with 10 parameters. The fitting rms of the Hamiltonian is 2.12 cm-1. With the parameters and Lie algebraic theory, we give the analytical expression of the potential energy surface, which helps us to calculate the dissociation energy and force constants of S2O in the electronic ground state.

  2. Surface recombination of oxygen atoms in O2 plasma at increased pressure: II. Vibrational temperature and surface production of ozone

    Science.gov (United States)

    Lopaev, D. V.; Malykhin, E. M.; Zyryanov, S. M.

    2011-01-01

    Ozone production in an oxygen glow discharge in a quartz tube was studied in the pressure range of 10-50 Torr. The O3 density distribution along the tube diameter was measured by UV absorption spectroscopy, and ozone vibrational temperature TV was found comparing the calculated ab initio absorption spectra with the experimental ones. It has been shown that the O3 production mainly occurs on a tube surface whereas ozone is lost in the tube centre where in contrast the electron and oxygen atom densities are maximal. Two models were used to analyse the obtained results. The first one is a kinetic 1D model for the processes occurring near the tube walls with the participation of the main particles: O(3P), O2, O2(1Δg) and O3 molecules in different vibrational states. The agreement of O3 and O(3P) density profiles and TV calculated in the model with observed ones was reached by varying the single model parameter—ozone production probability (\\gamma_{O_{3}}) on the quartz tube surface on the assumption that O3 production occurs mainly in the surface recombination of physisorbed O(3P) and O2. The phenomenological model of the surface processes with the participation of oxygen atoms and molecules including singlet oxygen molecules was also considered to analyse \\gamma_{O_{3}} data obtained in the kinetic model. A good agreement between the experimental data and the data of both models—the kinetic 1D model and the phenomenological surface model—was obtained in the full range of the studied conditions that allowed consideration of the ozone surface production mechanism in more detail. The important role of singlet oxygen in ozone surface production was shown. The O3 surface production rate directly depends on the density of physisorbed oxygen atoms and molecules and can be high with increasing pressure and energy inputted into plasma while simultaneously keeping the surface temperature low enough. Using the special discharge cell design, such an approach opens up the

  3. Vibrational spectrum at a water surface: a hybrid quantum mechanics/molecular mechanics molecular dynamics approach.

    Science.gov (United States)

    Ishiyama, Tatsuya; Takahashi, Hideaki; Morita, Akihiro

    2012-03-28

    A hybrid quantum mechanics/molecular mechanics (QM/MM) molecular dynamics (MD) simulation is applied to the calculation of surface orientational structure and vibrational spectrum (second-order nonlinear susceptibility) at the vapor/water interface for the first time. The surface orientational structure of the QM water molecules is consistent with the previous MD studies, and the calculated susceptibility reproduces the experimentally reported one, supporting the previous results using the classical force field MD simulation. The present QM/MM MD simulation also demonstrates that the positive sign of the imaginary part of the second-order nonlinear susceptibility at the lower hydrogen bonding OH frequency region originates not from individual molecular orientational structure, but from cooperative electronic structure through the hydrogen bonding network.

  4. An ab initio potential energy surface and vibrational energy levels of HXeBr

    Institute of Scientific and Technical Information of China (English)

    Zheng Guo Huang; En Cui Yang; Dai Qian Xie

    2008-01-01

    A three-dimensional global potential energy surface for the electronic ground state of HXeBr molecule is constructed from morethan 4200 ab initio points. These points are generated using an internally contracted multi-reference configuration interactionmethod with the Davidson correction (icMRCI + Q) and large basis sets. The stabilities and dissociation barriers are identified fromthe potential energy surfaces. The three-body dissociation channel is found to be the dominate dissociation channel for HXeBr.Based on the obtained potentials, low-lying vibrational energy levels of HXeBr calculated using the Lanczos algorithm is found tobe in good agreement with the available experimental band origins.2008 Zheng Guo Huang. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

  5. Vibrational properties and specific heat of core-shell Ag-Au icosahedral nanoparticles.

    Science.gov (United States)

    Sauceda, Huziel E; Garzón, Ignacio L

    2015-11-14

    The vibrational density of states (VDOS) of metal nanoparticles can be a fingerprint of their geometrical structure and determine their low-temperature thermal properties. Theoretical and experimental methods are available nowadays to calculate and measure it over a size range of 1-4 nm. In this work, we present theoretical results regarding the VDOS of Ag-Au icosahedral nanoparticles with a core-shell structure in that size range (147-923 atoms). The results are obtained by changing the size and type of atoms in the core-shell structure. For all sizes investigated, a smooth and monotonic variation of the VDOSs from Ag to Au is obtained by increasing the number of core Au atoms, and vice versa. Nevertheless, the Ag561Au362 nanoparticle, with a Ag core, shows an anomalous enhancement at low frequencies. An analysis of the calculated VDOSs indicates that as a general trend the low-frequency region is mainly due to the shell contribution, whereas at high frequencies the core effect would be dominant. A linear variation with size is obtained for the period of quasi-breathing mode (QBM), in agreement with the behaviour obtained for pure Ag and Au nanoparticles. A non-monotonic variation is obtained for the QBM frequency as a function of the Ag concentration for all nanoparticles investigated. The calculated specific heat at low temperatures of the Ag-Au nanoparticles is smaller (larger) than the corresponding one calculated for the pure Au (Ag) nanoparticles of same size. Nevertheless, the enhancement of VDOS at low frequencies of the Ag561Au362 nanoparticle with a Ag core induced larger values of specific heat than those of the pure Au923 nanoparticle in the temperature range of 5-15 K.

  6. Low frequency vibrations induce malformations in two aquatic species in a frequency-, waveform-, and direction-specific manner.

    Directory of Open Access Journals (Sweden)

    Laura N Vandenberg

    Full Text Available Environmental toxicants such as industrial wastes, air particulates from machinery and transportation vehicles, and pesticide run-offs, as well as many chemicals, have been widely studied for their effects on human and wildlife populations. Yet other potentially harmful environmental pollutants such as electromagnetic pulses, noise and vibrations have remained incompletely understood. Because developing embryos undergo complex morphological changes that can be affected detrimentally by alterations in physical forces, they may be particularly susceptible to exposure to these types of pollutants. We investigated the effects of low frequency vibrations on early embryonic development of two aquatic species, Xenopus laevis (frogs and Danio rerio (zebrafish, specifically focusing on the effects of varying frequencies, waveforms, and applied direction. We observed treatment-specific effects on the incidence of neural tube defects, left-right patterning defects and abnormal tail morphogenesis in Xenopus tadpoles. Additionally, we found that low frequency vibrations altered left-right patterning and tail morphogenesis, but did not induce neural tube defects, in zebrafish. The results of this study support the conclusion that low frequency vibrations are toxic to aquatic vertebrates, with detrimental effects observed in two important model species with very different embryonic architectures.

  7. An ab initio potential energy surface and vibrational states of MgH2(1(1)A').

    Science.gov (United States)

    Li, Hui; Xie, Daiqian; Guo, Hua

    2004-09-01

    A three-dimensional global potential energy surface for the ground electronic state of MgH(2) is constructed from more than 3000 ab initio points calculated using the internally contracted multireference configuration interaction method with the Davidson correction at the complete basis set limit. Low-lying vibrational energy levels of MgH(2) and MgD(2) are calculated using the Lanczos algorithm, and found to be in good agreement with known experimental band origins. The majority of the vibrational energy levels up to 8000 cm(-1) are assigned with normal mode quantum numbers. However, our results indicate a gradual transition from a normal mode regime for the stretching vibrations at low energies to a local mode regime near 7400 cm(-1), as evidenced by a decreasing energy gap between the (n(1),0,0) and (n(1)-1,0,1) vibrational states and bifurcation of the corresponding wave functions.

  8. Possible evidence of surface vibration of strange stars from stellar observations

    CERN Document Server

    Ray, S; Bhowmick, S; Ray, Subharthi; Dey, Jishnu; Bhowmick, Mira Dey & Siddhartha

    2004-01-01

    Emission lines in the eV and keV range by certain stellar candidates from their recent analysis invoke the question of their possible origin. These stars under consideration, are the 4U 0614+091 (0.65, 0.86, and 1.31 keV), 2S 0918-549 (0.8 keV with width 55 eV), 4U 1543-624 (0.7 keV), 4U 1850-087 (0.7 keV) and 4U 1820-30 (0.6 and 0.9 keV) and also the 0.6 keV excess emission in RX J170930.2-263927. Recently, it has been suggested that the resonance absorption at ~ in 0.7, 1.4, 2.1 and 2.8 keV 1E1207-5209 and 0.35, 0.7 and 1.4 keV RX J1856.5-3754 are due to harmonic surface vibrations in strange stars. We propose that these harmonic vibrations may also responsible for emission lines in the above mentioned compact stellar candidates.

  9. Ozone kinetics in low-pressure discharges: vibrationally excited ozone and molecule formation on surfaces

    Science.gov (United States)

    Marinov, Daniil; Guerra, Vasco; Guaitella, Olivier; Booth, Jean-Paul; Rousseau, Antoine

    2013-10-01

    A combined experimental and modeling investigation of the ozone kinetics in the afterglow of pulsed direct current discharges in oxygen is carried out. The discharge is generated in a cylindrical silica tube of radius 1 cm, with short pulse durations between 0.5 and 2 ms, pressures in the range 1-5 Torr and discharge currents ˜40-120 mA. Time-resolved absolute concentrations of ground-state atoms and ozone molecules were measured simultaneously in situ, by two-photon absorption laser-induced fluorescence and ultraviolet absorption, respectively. The experiments were complemented by a self-consistent model developed to interpret the results and, in particular, to evaluate the roles of vibrationally excited ozone and of ozone formation on surfaces. It is found that vibrationally excited ozone, O_3^{*} , plays an important role in the ozone kinetics, leading to a decrease in the ozone concentration and an increase in its formation time. In turn, the kinetics of O_3^{*} is strongly coupled with those of atomic oxygen and O2(a 1Δg) metastables. Ozone formation at the wall does not contribute significantly to the total ozone production under the present conditions. Upper limits for the effective heterogeneous recombination probability of O atoms into ozone are established.

  10. Study on the nano machining process with a vibrating AFM tip on the polymer surface

    Energy Technology Data Exchange (ETDEWEB)

    Liu Weitao [State Key Laboratory of Robotics and Systems, Robotics Institute, Harbin Institute of Technology, Harbin 150080 (China); Center for Precision Engineering, Harbin Institute of Technology, Harbin, Heilongjiang 150001 (China); Yan Yongda, E-mail: yanyongda@yahoo.com.cn [State Key Laboratory of Robotics and Systems, Robotics Institute, Harbin Institute of Technology, Harbin 150080 (China); Center for Precision Engineering, Harbin Institute of Technology, Harbin, Heilongjiang 150001 (China); Hu Zhenjiang; Zhao Xuesen; Yan Jiucun; Dong Shen [Center for Precision Engineering, Harbin Institute of Technology, Harbin, Heilongjiang 150001 (China)

    2012-01-15

    The polymer has been proved to be nano machined by a vibrating tip in tapping mode of Atomic Force Microscope (AFM). The force between the tip and the surface is an important factor which determines success of the machining process. Controlling this force with high accuracy is the foundation of nanomachining in AFM tapping mode. To achieve a deeper understanding on this process, the tip is modeled as a driving oscillator with damping. Factors affecting the nano machining process are studied. The Hertz elastic contact theory is used to calculate the maximum contact pressure applied by the tip which is employed as a criterion to judge the deformation state of the sample. The simulation results show that: The driven amplitude can be used as a main parameter of controlling the machined depth. Sharper tips and harder cantilevers should be used for successful nanomachining with the vibrating tip. Under the same conditions, a larger tip radius will not only result in the machining error, but also lead to failure of the nanomachining process. The higher driving frequency will lead to a larger tapping force. However it cannot be used as a parameter to control the machined depth because of its narrow variation range. But it is a main error source for the nanomachining process in AFM tapping mode. Moreover, a larger Young's modulus polymer sample will induce a smaller machined depth, a larger maximum contact pressure and a bigger tapping force.

  11. Numerical modelling of ground-borne noise and vibration in buildings due to surface rail traffic

    Science.gov (United States)

    Fiala, P.; Degrande, G.; Augusztinovicz, F.

    2007-04-01

    This paper deals with the numerical computation of the structural and acoustic response of a building to an incoming wave field generated by high-speed surface railway traffic. The source model consists of a moving vehicle on a longitudinally invariant track, coupled to a layered ground modelled with a boundary element formulation. The receiver model is based on a substructuring formulation and consists of a boundary element model of the soil and a finite element model of the structure. The acoustic response of the building's rooms is computed by means of a spectral finite element formulation. The paper investigates the structural and acoustic response of a multi-story portal frame office building up to a frequency of 150 Hz to the passage of a Thalys high-speed train at constant velocity. The isolation performance of three different vibration countermeasures: a floating-floor, a room-in-room, and base-isolation, are examined.

  12. Towards vibrational spectroscopy on surface-attached colloids performed with a quartz crystal microbalance

    Directory of Open Access Journals (Sweden)

    Diethelm Johannsmann

    2016-12-01

    Full Text Available Colloidal spheres attached to a quartz crystal microbalance (QCM produce the so-called “coupled resonances”. They are resonators of their own, characterized by a particle resonance frequency, a resonance bandwidth, and a modal mass. When the frequency of the main resonator comes close to the frequency of the coupled resonance, the bandwidth goes through a maximum. A coupled resonance can be viewed as an absorption line in acoustic shear-wave spectroscopy. The known concepts from spectroscopy apply. This includes the mode assignment problem, selection rules, and the oscillator strength. In this work, the mode assignment problem was addressed with Finite Element calculations. These reveal that a rigid sphere in contact with a QCM displays two modes of vibration, termed “slipping” and “rocking”. In the slipping mode, the sphere rotates about its center; it exerts a tangential force onto the resonator surface at the point of contact. In the rocking mode, the sphere rotates about the point of contact; it exerts a torque onto the substrate. In liquids, both axes of rotation are slightly displaced from their ideal positions. Characteristic for spectroscopy, the two modes do not couple to the mechanical excitation equally well. The degree of coupling is quantified by an oscillator strength. Because the rocking mode mostly exerts a torque (rather than a tangential force, its coupling to the resonator's tangential motion is weak; the oscillator strength consequently is small. Recent experiments on surface-adsorbed colloidal spheres can be explained by the mode of vibration being of the rocking type.

  13. Specification guidelines for surface preparation of concrete prior to repair

    OpenAIRE

    Courard, Luc; Bissonnette, Benoît; Garbacz, Andrzej

    2017-01-01

    The repair of concrete requests specific preparation operations needed for guaranteeing compatibility between substrate and new materials as well as the development of adhesion properties. These specification guidelines contain design and construction recommendations for surface preparation of concrete for repair and overlay. The paper summarizes current knowledge, best practices and results of the research concerning the surface preparation of concrete prior to application of repair/overlay ...

  14. Influence of Whole Body Vibration and Specific Warm-ups on Force during an Isometric Mid-Thigh Pull

    Directory of Open Access Journals (Sweden)

    Vanessa L. Cazás-Moreno

    2015-10-01

    Full Text Available Purpose: The purpose of this study was to investigate the effects of general and specific warm-up protocols on rate of force development (RFD, relative RFD (rRFD, ground reaction force (GRF and relative ground reaction force (rGRF during an isometric mid-thigh pull (IMTP, after WBV exposure. Methods: Fifteen healthy recreationally trained males  (age: 24.1 ± 2.3 yrs, height: 72.9 ± 7.8 cm; mass: 86.9 ± 8.3 completed five protocols: baseline, isometric vibration (iVib, isometric no vibration (iNV, dynamic vibration (dVib and dynamic no vibration (dNV. The baseline was completed without any warm-up prior to the IMTP. The intervention protocols had the same prescription of 4 sets of 30-second bouts of quarter squats (dynamic [DQS] and isometric [IQS] on the WBV platform with or without vibration. Following a one-minute rest period after each protocol, participants completed three maximal IMTPs. Results: Repeated measures ANOVA with a Bonferroni post hoc demonstrated that RFD in dNV (7657.8 ± 2292.5 N/s was significantly greater than iVib (7156.4 ± 2170.0 N/s. However, the other experimental trials for RFD demonstrated no significant differences (p>0.05. There were also no significant differences for rRFD, GRF or rGRF between protocols. Conclusion: These results demonstrate that a dynamic warm-up without WBV elicits greater RFD than an isometric warm-up with WBV prior to a maximal isometric exercise. Further research needs to be investigated utilizing dynamic and isometric warm-ups in conjunction with WBV and power output. Keywords: males, recreationally trained, power

  15. Chemical effects on vibrational properties of adsorbed molecules on metal surfaces: Coverage dependence

    Science.gov (United States)

    Ueba, H.

    1987-10-01

    Vibrational properties of chemisorbed molecules on metal surfaces are studied with a focus on the coverage dependent chemical shift of the frequencies. Available experimental data of a CO adsorption on transition metal and noble metal surfaces are analyzed in the light of the coverage dependent back-donation into the 2 π* orbitals of chemisorbed CO molecules. The vibrational frequency ωCO of the intramolecular stretching mode exhibits a downward shift of varying magnitude, depending on the amount of back-donation into the 2 π* orbitals of the chemisorbed CO. On increasing the coverage θ, ωCO usually increases due to the dipole-dipole interaction. On Cu surfaces, however, the shifts are relatively small, or in some cases, negative. So far, this anomalous frequency shift with θ is understood as a result of competitive effect between the upward dipole Ωdip and the downward chemical shift Ωchem associated with back-donation. The purpose of this paper is to establish the possible origin of the downward frequency shift through the electronic properties of an incomplete monolayer of adsorbates. The adsorbate density of states ρa is calculated by means of the coherent potential approximation, in which the electron hopping between the adsorbates (band formation effect) and the depolarization effect due to the proximity of ionized adsorbed molecules are taken into account. The change of the occupied portion of ρa and ρa ( ɛF) at the Fermi level ɛF with increasing θ then manifests itself in the coverage dependent Ωchem not only due to the static back-donation, but also due to the dynamical charge fluctuation during vibrational excitation. It is found that in a weakly chemisorbed system, such as CO/Cu, the negative Ωchem amounts to Ωdip at low θ. Consequently the apparent total frequency shift remains almost constant. As the coverage increases, Ωchem becomes larger than Ωdip due to the band effect. It is also shown that the variation of the back

  16. Comparison of pollination and defensive buzzes in bumblebees indicates species-specific and context-dependent vibrations

    Science.gov (United States)

    De Luca, Paul A.; Cox, Darryl A.; Vallejo-Marín, Mario

    2014-04-01

    Bees produce vibrations in many contexts, including for defense and while foraging. Buzz pollination is a unique foraging behavior in which bees vibrate the anthers of flowers to eject pollen which is then collected and used as food. The relationships between buzzing properties and pollen release are well understood, but it is less clear to what extent buzzing vibrations vary among species, even though such information is crucial to understanding the functional relationships between bees and buzz-pollinated plants. Our goals in this study were (1) to examine whether pollination buzzes differ from those produced during defense, (2) to evaluate the similarity of buzzes between different species of bumblebees ( Bombus spp.), and (3) to determine if body size affects the expression of buzzing properties. We found that relative peak amplitude, peak frequency, and duration were significantly different between species, but only relative peak amplitude differed between pollination and defensive buzzes. There were significant interactions between species and buzz type for peak frequency and duration, revealing that species differed in their patterns of expression in these buzz properties depending on the context. The only parameter affected by body size was duration, with larger bees producing shorter buzzes. Our findings suggest that although pollination and defensive buzzes differ in some properties, variability in buzz structure also exhibits a marked species-specific component. Species differences in pollination buzzes may have important implications for foraging preferences in bumblebees, especially if bees select flowers best matched to release pollen for their specific buzzing characteristics.

  17. Size-dependent free vibration analysis of rectangular nanoplates with the consideration of surface effects using finite difference method

    Directory of Open Access Journals (Sweden)

    Morteza karimi

    2015-07-01

    Full Text Available In this article, finite difference method (FDM is used to study the size-dependent free vibration characteristics of rectangular nanoplates considering the surface stress effects. To include the surface effects in the equations, Gurtin-Murdoch continuum elasticity approach has been employed. The effects of surface properties including the surface elasticity, surface residual stress and surface mass density are considered to be the main causes for size-dependent behaviors that arise from the increase in surface-to-volume ratios at smaller scales. Numerical results are presented to demonstrate the difference between the natural frequency obtained by considering the surface effects and that obtained without considering surface properties. It is observed that the effects of surface properties tend to diminish in thicker nanoplates, and vice versa.

  18. Spectroscopic determination of ground and excited state vibrational potential energy surfaces

    Science.gov (United States)

    Laane, Jaan

    Far-infrared spectra, mid-infrared combination band spectra, Raman spectra, and dispersed fluorescence spectra of non-rigid molecules can be used to determine the energies of many of the quantum states of conformationally important vibrations such as out-of-plane ring modes, internal rotations, and molecular inversions in their ground electronic states. Similarly, the fluorescence excitation spectra of jet-cooled molecules, together with electronic absorption spectra, provide the information for determining the vibronic energy levels of electronic excited states. One- or two-dimensional potential energy functions, which govern the conformational changes along the vibrational coordinates, can be determined from these types of data for selected molecules. From these functions the molecular structures, the relative energies between different conformations, the barriers to molecular interconversions, and the forces responsible for the structures can be ascertained. This review describes the experimental and theoretical methodology for carrying out the potential energy determinations and presents a summary of work that has been carried out for both electronic ground and excited states. The results for the out-of-plane ring motions of four-, five-, and six-membered rings will be presented, and results for several molecules with unusual properties will be cited. Potential energy functions for the carbonyl wagging and ring modes for several cyclic ketones in their S1(n,pi*) states will also be discussed. Potential energy surfaces for the three internal rotations, including the one governing the photoisomerization process, will be examined for trans-stilbene in both its S0 and S1(pi,pi*) states. For the bicyclic molecules in the indan family, the two-dimensional potential energy surfaces for the highly interacting ring-puckering and ring-flapping motions in both the S0 and S1(pi,pi*) states have also been determined using all of the spectroscopic methods mentioned above

  19. Raman and surface-enhanced Raman spectroscopy of amino acids and nucleotide bases for target bacterial vibrational mode identification

    Science.gov (United States)

    Guicheteau, Jason; Argue, Leanne; Hyre, Aaron; Jacobson, Michele; Christesen, Steven D.

    2006-05-01

    Raman and surface-enhanced Raman spectroscopy (SERS) studies of bacteria have reported a wide range of vibrational mode assignments associated with biological material. We present Raman and SER spectra of the amino acids phenylalanine, tyrosine, tryptophan, glutamine, cysteine, alanine, proline, methionine, asparagine, threonine, valine, glycine, serine, leucine, isoleucine, aspartic acid and glutamic acid and the nucleic acid bases adenosine, guanosine, thymidine, and uridine to better characterize biological vibrational mode assignments for bacterial target identification. We also report spectra of the bacteria Bacillus globigii, Pantoea agglomerans, and Yersinia rhodei along with band assignments determined from the reference spectra obtained.

  20. Bi-objective robust optimization of machined surface quality and productivity under vibrations limitation

    Directory of Open Access Journals (Sweden)

    Sahali M.A.

    2015-01-01

    Full Text Available In this contribution, a bi-objective robust optimization of cutting parameters, with the taking into account uncertainties inherent in the tool wear and the tool deflection for a turning operation is presented. In a first step, we proceed to the construction of substitution models that connect the cutting parameters to the variables of interest based on design of experiments. Our two objectives are the best machined surface quality and the maximum productivity under consideration of limitations related to the vibrations and the range of the three cutting parameters. Then, using the developed genetic algorithm that based on a robust evaluation mechanism of chromosomes by Monte-Carlo simulations, the influence and interest of the uncertainties integration in the machining optimization is demonstrated. After comparing the classical and robust Pareto fronts, A surface quality less efficient but robust can be obtained with the consideration of uncontrollable factors or uncertainties unlike that provides the deterministic and classical optimization for the same values of productivity.

  1. Surface Effect on Vibration of Y-SWCNTs Embedded on Pasternak Foundation Conveying Viscose Fluid

    Directory of Open Access Journals (Sweden)

    A. Ghorbanpour-Arani

    2015-01-01

    Full Text Available Surface and small scale effects on free transverse vibration of a single-walled carbon nanotube (SWCNT fitted with Y-junction at downstream end conveying viscose fluid is investigated in this article based on Euler-Bernoulli beam (EBB model. Nonlocal elasticity theory is employed to consider small scale effects due to its simplicity and efficiency. The energy method and Hamilton’s principle are used to establish the corresponding motion equation. To discretize and solve the governing equation of motion the Galerkin method is applied. Moreover, the small-size effect, angle of Y-junction, surface layer and Pasternak elastic foundation are studied in detail. Regarding fluid flow effects, it has been concluded that the fluid flow is an effective factor on increasing the instability of Y-SWCNT. Results show that increasing the angle of Y-junction enhances the flutter fluid velocity where the first and second modes are merged. This work could be used in medical application and design of nano-electromechanical devices such as measuring the density of blood flowing through such nanotubes.

  2. FFT and Wavelet-Based Analysis of the Influence of Machine Vibrations on Hard Turned Surface Topographies

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    With hard turning, which is an attractive alternative to existing grinding processes, surface quality is of great importance. Signal processing techniques were used to relate workpiece surface topography to the dynamic behavior of the machine tool. Spatial domain frequency analyses based on fast Fourier transform were used to analyze the tool behavior. Wavelet reconstruction was used for profile filtering. The results show that machine vibration remarkably affects the surface topography at small feed rates, but has negligible effect at high feed rates. The analyses also show how to control the surface quality during hard turning.

  3. Optically probing Al—O and O—H vibrations to characterize water adsorption and surface reconstruction on α-alumina: An experimental and theoretical study

    Energy Technology Data Exchange (ETDEWEB)

    Tong, Yujin, E-mail: tong@fhi-berlin.mpg.de; Kirsch, Harald; Wolf, Martin; Campen, R. Kramer, E-mail: campen@fhi-berlin.mpg.de [Fritz Haber Institute of the Max Planck Society, 14195 Berlin (Germany); Wirth, Jonas; Saalfrank, Peter [Institute of Chemistry, University of Potsdam, 14476 Potsdam OT Golm (Germany)

    2015-02-07

    Oxide/water interfaces are ubiquitous in a wide variety of applications and the environment. Despite this ubiquity, and attendant decades of study, gaining molecular level insight into water/oxide interaction has proven challenging. In part, this challenge springs from a lack of tools to concurrently characterize changes in surface structure (i.e., water/oxide interaction from the perspective of the solid) and O—H population and local environment (i.e., water/oxide interaction from the water perspective). Here, we demonstrate the application of surface specific vibrational spectroscopy to the characterization of the interaction of the paradigmatic α-Al{sub 2}O{sub 3}(0001) surface and water. By probing both the interfacial Al—O (surface phonon) and O—H spectral response, we characterize this interaction from both perspectives. Through electronic structure calculation, we assign the interfacial Al—O response and rationalize its changes on surface dehydroxylation and reconstruction. Because our technique is all-optical and interface specific, it is equally applicable to oxide surfaces in vacuum, ambient atmospheres and at the solid/liquid interface. Application of this approach to additional alumina surfaces and other oxides thus seems likely to significantly expand our understanding of how water meets oxide surfaces and thus the wide variety of phenomena this interaction controls.

  4. Nano-porous ultra-high specific surface ultrafine fibers

    Institute of Scientific and Technical Information of China (English)

    LI Xinsong; NIE Guangyu

    2004-01-01

    Nano-porous ultra-high specific surface ultrafine fibers are created by the method of "electrospinning-phase separation-leaching" (EPL) for the first time. First of all, polymer solutions of polyacrylonitrile (PAN) and polyvinylpyrrolidone (PVP) blends dissolved in co-solvent are electrospun to make ultrafine fibers when charged to high voltages. The incompatibility of PAN and PVP induces phase separation to form microdomains of PVP in the polymer blend ultrafine fibers. Then, PVP microdomains in the blend fibers are leached out in water, and porous PAN ultrafine fibers are obtained. Lastly, the surface and cross-section of the porous ultrafine fibers are observed in detail by field emission scanning electron microscope (FESEM), and the specific surface of the ultrafine fibers is measured by means of nitrogen absorption. With increasing the content of PVP, the specific surface area of the ultrafine fibers increases apparently. The specific surface area of the porous ultrafine fibers with the diameter of 2130 nm is more than 70 m2·g-1. The cross-section of the PAN porous ultrafine fibers after leaching of PVP microdomains from polymer blend fibers with the feed ratio of PAN/PVP of 10/20 shows the characteristic of porous structure with pore diameter of ca 30 nm according to FESEM photo.

  5. Surface Modification on Acoustic Wave Biosensors for Enhanced Specificity

    Directory of Open Access Journals (Sweden)

    Nathan D. Gallant

    2012-09-01

    Full Text Available Changes in mass loading on the surface of acoustic biosensors result in output frequency shifts which provide precise measurements of analytes. Therefore, to detect a particular biomarker, the sensor delay path must be judiciously designed to maximize sensitivity and specificity. B-cell lymphoma 2 protein (Bcl-2 found in urine is under investigation as a biomarker for non-invasive early detection of ovarian cancer. In this study, surface chemistry and biofunctionalization approaches were evaluated for their effectiveness in presenting antibodies for Bcl-2 capture while minimizing non-specific protein adsorption. The optimal combination of sequentially adsorbing protein A/G, anti-Bcl-2 IgG and Pluronic F127 onto a hydrophobic surface provided the greatest signal-to-noise ratio and enabled the reliable detection of Bcl-2 concentrations below that previously identified for early stage ovarian cancer as characterized by a modified ELISA method. Finally, the optimal surface modification was applied to a prototype acoustic device and the frequency shift for a range of Bcl-2 concentration was quantified to demonstrate the effectiveness in surface acoustic wave (SAW-based detection applications. The surface functionalization approaches demonstrated here to specifically and sensitively detect Bcl-2 in a working ultrasonic MEMS biosensor prototype can easily be modified to detect additional biomarkers and enhance other acoustic biosensors.

  6. Specific surface as a measure of burial diagenesis of chalk

    DEFF Research Database (Denmark)

    Borre, Mai Kirstine; Lind, Ida; Mortensen, Jeanette

    1997-01-01

    ODP Leg 130, Site 807, in the western equatorial Pacific, penetrates a sequence of pelagic carbonate ooze, chalk and limestone. Compaction, recrystallisation and cementation of the carbonate matrix are diagenetic processes expected to be taking place more or less simultaneously. In order to assess...... the relative importance of the three processes, simple models have been established to illustrate changes in pore space, particle size and -shape and the resulting trends in the specific surface. Specific surface and porosity of the samples were measured using image analysis on electron micrographs of polished...

  7. Effects of electronic relaxation processes on vibrational linewidths of adsorbates on surfaces: The case of CO/Cu(100)

    Science.gov (United States)

    Novko, D.; Alducin, M.; Blanco-Rey, M.; Juaristi, J. I.

    2016-12-01

    We investigate nonadiabatic effects for the vibrational stretch mode of the CO molecule adsorbed on the top site of the Cu(100) surface. By studying the long-wavelength (q ≈0 ) imaginary and real parts of the density functional theory based phonon self-energy due to the electron-phonon coupling Πλ we obtain the phonon linewidth and the frequency renormalization of the CO stretch mode, respectively. To simulate electronic scattering processes that lead to further damping of the phonon modes we include a phenomenological damping in the phonon self-energy, as well as in the single-electron spectral function that enters Πλ, through the momentum distribution function. For the specific case of electron-impurity scattering we explicitly show how this process opens the indirect intraband channel and broadens the linewidth of the CO stretch mode. To emphasize the importance of accounting for electronic scattering processes we compare the phonon linewidths in the clean noninteracting limit (infinite electron lifetime) and when electronic scattering processes are phenomenologically included (finite electron lifetime) with available experimental data. We find that the agreement with experiments is improved in the latter case.

  8. Analysis of the Effects of Surface Pitting and Wear on the Vibrations of a Gear Transmission System

    Science.gov (United States)

    Choy, F. K.; Polyshchuk, V.; Zakrajsek, J. J.; Handschuh, R. F.; Townsend, D. P.

    1994-01-01

    A comprehensive procedure to simulate and analyze the vibrations in a gear transmission system with surface pitting, 'wear' and partial tooth fracture of the gear teeth is presented. An analytical model was developed where the effects of surface pitting and wear of the gear tooth were simulated by phase and magnitude changes in the gear mesh stiffness. Changes in the gear mesh stiffness were incorporated into each gear-shaft model during the global dynamic simulation of the system. The overall dynamics of the system were evaluated by solving for the transient dynamics of each shaft system simultaneously with the vibration of the gearbox structure. In order to reduce the number of degrees-of-freedom in the system, a modal synthesis procedure was used in the global transient dynamic analysis of the overall transmission system. An FFT procedure was used to transform the averaged time signal into the frequency domain for signature analysis. In addition, the Wigner-Ville distribution was also introduced to examine the gear vibration in the joint time frequency domain for vibration pattern recognition. Experimental results obtained from a gear fatigue test rig at NASA Lewis Research Center were used to evaluate the analytical model.

  9. Vibration and acoustic radiation of a finite cylindrical shell submerged at finite depth from the free surface

    Science.gov (United States)

    Guo, Wenjie; Li, Tianyun; Zhu, Xiang; Miao, Yuyue; Zhang, Guanjun

    2017-04-01

    The far-field acoustic radiation of a cylindrical shell with finite length submerged at finite depth from the water surface is studied. Two steps are utilized to solve the problem. The first step is to determine the vibration response of the submerged cylindrical shell by using an analytical method and the second one is to determine the far field sound radiation with the boundary element method. To address the vibration responses of the shell analytically, the cylindrical shell and surrounding fluid are described by the Flügge shell equations and Laplace equation in the cylindrical coordinate system respectively. The free surface effect is taken into consideration by using the image method and the Graf's addition theorem. The reliability and efficiency of the present method are validated by comparison with the finite element method. Then, based on the vibration responses of the shell obtained from the first step, the far-field sound pressure is computed by using the boundary element method. It is found that the vibration of the cylindrical shell submerged at finite depth from the free surface tends to be the same as that in infinite fluid when the submerged depth exceeds a certain value. The frequency and the submerged depth have crucial effects on the fluctuation of the far-field sound pressure, while for the curve of sound pressure level versus immersion depth, the ratio of the distance between the adjacent peak points of sound pressure to the wavelength is independent of the frequency. Moreover, the petal number of the directivity of the far-field sound pressure increases with the increase of the frequency and the submerged depth. The work provides more understanding on the vibration and acoustic radiation behavior of a finite cylindrical shell submerged at finite depth.

  10. Vibrationally specific photoionization cross sections of acrolein leading to the X̃²A' ionic state.

    Science.gov (United States)

    López-Domínguez, Jesús A; Lucchese, Robert R; Fulfer, K D; Hardy, David; Poliakoff, E D; Aguilar, A A

    2014-09-07

    The vibrational branching ratios in the photoionization of acrolein for ionization leading to the X̃²A' ion state were studied. Computed logarithmic derivatives of the cross section and the corresponding experimental data derived from measured vibrational branching ratios for several normal modes (ν9, ν10, ν11, and ν12) were found to be in relatively good agreement, particularly for the lower half of the 11-100 eV photon energy range considered. Two shape resonances have been found near photon energies of 15.5 and 23 eV in the photoionization cross section and have been demonstrated to originate from the partial cross section of the A' scattering symmetry. The wave functions computed at the resonance complex energies are delocalized over the whole molecule. By looking at the dependence of the cross section on the different normal mode displacements together with the wave function at the resonant energy, a qualitative explanation is given for the change of the cross sections with respect to changing geometry.

  11. Vibrations and spatial patterns in biomimetic surfaces: using the shark-skin effect to control blood clotting.

    Science.gov (United States)

    Ramachandran, Rahul; Maani, Nazanin; Rayz, Vitaliy L; Nosonovsky, Michael

    2016-08-01

    We study the effect of small-amplitude fast vibrations and small-amplitude spatial patterns on various systems involving wetting and liquid flow, such as superhydrophobic surfaces, membranes and flow pipes. First, we introduce a mathematical method of averaging the effect of small spatial and temporal patterns and substituting them with an effective force. Such an effective force can change the equilibrium state of a system as well as a phase state, leading to surface texture-induced and vibration-induced phase control. Vibration and patterns can effectively jam holes in vessels with liquid, separate multi-phase flow, change membrane properties, result in propulsion and locomotion and lead to many other multi-scale, nonlinear effects including the shark-skin effect. We discuss the application of such effects to blood flow for novel biomedical 'haemophobic' applications which can prevent blood clotting and thrombosis by controlling the surface pattern at a wall of a vessel (e.g. a catheter or stent).This article is part of the themed issue 'Bioinspired hierarchically structured surfaces for green science'.

  12. Estimation of Specific Surface Area using Langmuir Isotherm ...

    African Journals Online (AJOL)

    Michael Horsfall

    13.884) units in multiple of 10-3km2kg-1. The reliability of the ... In this present study, the linear least- squares method via the correlation coefficient (R2) was used (Yuh,2006). ... specific surface area determination has been adopted widely for ...

  13. Three-dimensional ab initio dipole moment surfaces and stretching vibrational band intensities of the XH3 molecules

    Institute of Scientific and Technical Information of China (English)

    Liu An-Wen; Hu Shui-Ming; Ding Yun; Zhu Qing-Shi

    2005-01-01

    Stretching vibrational band intensities of XH3 (X=N, Sb) molecules are investigated employing three-dimensional dipole moment surfaces combined with the local mode Hamiltonian model. The dipole moment surfaces of NH3 and SbH3 are calculated with the density functional theory and at the correlated MP2 level, respectively. The calculated band intensities are in good agreement with the available experimental data. The contribution to the band intensities from the different terms in the polynomial expansion of the dipole moments of four group V hydrides (NH3, PH3, AsH3 and SbH3) are discussed. It is concluded that the breakdown of the bond dipole approximation must be considered.The intensity "borrowing" effect due to the wave function mixing among the stretching vibrational states is found to be less significant for the molecules that reach the local mode limit.

  14. Site-specific conformational determination in thermal unfolding studies of helical peptides using vibrational circular dichroism with isotopic substitution

    Science.gov (United States)

    Silva, R. A. G. D.; Kubelka, Jan; Bour, Petr; Decatur, Sean M.; Keiderling, Timothy A.

    2000-01-01

    Understanding the detailed mechanism of protein folding requires dynamic, site-specific stereochemical information. The short time response of vibrational spectroscopies allows evaluation of the distribution of populations in rapid equilibrium as the peptide unfolds. Spectral shifts associated with isotopic labels along with local stereochemical sensitivity of vibrational circular dichroism (VCD) allow determination of the segment sequence of unfolding. For a series of alanine-rich peptides that form α-helices in aqueous solution, we used isotopic labeling and VCD to demonstrate that the α-helix noncooperatively unwinds from the ends with increasing temperature. For these blocked peptides, the C-terminal is frayed at 5°C. Ab initio level theoretical simulations of the IR and VCD band shapes are used to analyze the spectra and to confirm the conformation of the labeled components. The VCD signals associated with the labeled residues are amplified by coupling to the nonlabeled parts of the molecule. Thus small labeled segments are detectable and stereochemically defined in moderately large peptides in this report of site-specific peptide VCD conformational analysis. PMID:10880566

  15. Quantum and classical vibrational relaxation dynamics of N-methylacetamide on ab initio potential energy surfaces

    CERN Document Server

    Fujisaki, Hiroshi; Hirao, Kimihiko; Straub, John E; Stock, Gerhard

    2008-01-01

    Employing extensive quantum-chemical calculations at the DFT/B3LYP and MP2 level, a quartic force field of isolated N-methylacetamide is constructed. Taking into account 24 vibrational degrees of freedom, the model is employed to perform numerically exact vibrational configuration interaction calculations of the vibrational energy relaxation of the amide I mode. It is found that the energy transfer pathways may sensitively depend on details of the theoretical description. Moreover, the exact reference calculations were used to study the applicability and accuracy of (i) the quasiclassical trajectory method, (ii) time-dependent second-order perturbation theory, and (iii) the instantaneous normal mode description of frequency fluctuations. Based on the results, several strategies to describe vibrational energy relaxation in biomolecular systems are discussed.

  16. Vibration of bioliquid-filled microtubules embedded in cytoplasm including surface effects using modified couple stress theory.

    Science.gov (United States)

    Ghorbanpour Arani, A; Abdollahian, M; Jalaei, M H

    2015-02-21

    This paper aims to investigate vibrational behavior of bioliquid-filled microtubules (MTs) embedded in cytoplasm considering surface effects. The interactions between the MT, considered as an orthotropic beam within the framework of Euler-Bernoulli beam (EBB) and Timoshenko beam (TB) models, and its surrounding elastic media are simulated by Pasternak foundation model. The modified couple stress theory (MCST) is applied so as to consider the small scale effects while motion equations are derived using energy method and Hamilto's principle for both EBB and TB models. Finally, an analytical method is employed to obtain the frequency of a bioliquid-filled MT, and therefore frequency-response curves are plotted to investigate the influences of small scale parameter, mass density of bioliquid, surface layer and surrounding elastic medium graphically. The results indicate that bioliquid and surface layers play a key role on the frequency of MTs and that the frequency of MTs is decreased with increasing of the mass density of the bioliquid. Vibration analysis of MTs is being considered as a vital problem since MTs look like the nervous system of the biological cells and transmit vibrational signals. It should be noted that the results of this work are hoped to be of use in advanced medical applications especially in the forthcoming use of MTs in transporters for bio-nanosensors.

  17. Vibration attenuation and shape control of surface mounted, embedded smart beam

    OpenAIRE

    Rathi, Vivek; Khan,Arshad Hussain

    2012-01-01

    Active Vibration Control (AVC) using smart structure is used to reduce the vibration of a system by automatic modification of the system structural response. AVC is widely used, because of its wide and broad frequency response range, low additional mass, high adaptability and good efficiency. A lot of research has been done on Finite Element (FE) models for AVC based on Euler Bernoulli Beam Theory (EBT). In the present work Timoshenko Beam Theory (TBT) is used to model a smart cantilever beam...

  18. Adsorption and desorption of hydrogen at nonpolar GaN (1 1 ¯ 00 ) surfaces: Kinetics and impact on surface vibrational and electronic properties

    Science.gov (United States)

    Lymperakis, L.; Neugebauer, J.; Himmerlich, M.; Krischok, S.; Rink, M.; Kröger, J.; Polyakov, V. M.

    2017-05-01

    The adsorption of hydrogen at nonpolar GaN (1 1 ¯00 ) surfaces and its impact on the electronic and vibrational properties is investigated using surface electron spectroscopy in combination with density functional theory (DFT) calculations. For the surface mediated dissociation of H2 and the subsequent adsorption of H, an energy barrier of 0.55 eV has to be overcome. The calculated kinetic surface phase diagram indicates that the reaction is kinetically hindered at low pressures and low temperatures. At higher temperatures ab initio thermodynamics show, that the H-free surface is energetically favored. To validate these theoretical predictions experiments at room temperature and under ultrahigh vacuum conditions were performed. They reveal that molecular hydrogen does not dissociatively adsorb at the GaN (1 1 ¯00 ) surface. Only activated atomic hydrogen atoms attach to the surface. At temperatures above 820 K, the attached hydrogen gets desorbed. The adsorbed hydrogen atoms saturate the dangling bonds of the gallium and nitrogen surface atoms and result in an inversion of the Ga-N surface dimer buckling. The signatures of the Ga-H and N-H vibrational modes on the H-covered surface have experimentally been identified and are in good agreement with the DFT calculations of the surface phonon modes. Both theory and experiment show that H adsorption results in a removal of occupied and unoccupied intragap electron states of the clean GaN (1 1 ¯00 ) surface and a reduction of the surface upward band bending by 0.4 eV. The latter mechanism largely reduces surface electron depletion.

  19. Mechanisms of free-surface breakup in vibration-induced liquid atomization

    Science.gov (United States)

    Vukasinovic, Bojan; Smith, Marc K.; Glezer, Ari

    2007-01-01

    The mechanisms of droplet formation that take place during vibration-induced drop atomization are investigated experimentally. Droplet ejection results from the breakup of transient liquid spikes that form following the localized collapse of free-surface waves. Breakup typically begins with capillary pinch-off of a droplet from the tip of the spike and can be followed by additional pinch-offs of satellite droplets if the corresponding capillary number is sufficiently small (e.g., in low-viscosity liquids). If the capillary number is increased (e.g., in viscous liquids), breakup first occurs near the base of the spike, with or without subsequent breakup of the detached, thread-like spike. The formation of these detached threads is governed by a breakup mechanism that is separated from the tip-dominated capillary pinch-off mechanism by an order of magnitude in terms of dimensionless driving frequency f*. The dependence of breakup time and unbroken spike length on fluid and driving parameters is established over a broad range of dimensionless driving frequencies (10-3

  20. Full Dimensional Vibrational Calculations for Methane Using AN Accurate New AB Initio Based Potential Energy Surface

    Science.gov (United States)

    Majumder, Moumita; Dawes, Richard; Wang, Xiao-Gang; Carrington, Tucker; Li, Jun; Guo, Hua; Manzhos, Sergei

    2014-06-01

    New potential energy surfaces for methane were constructed, represented as analytic fits to about 100,000 individual high-level ab initio data. Explicitly-correlated multireference data (MRCI-F12(AE)/CVQZ-F12) were computed using Molpro [1] and fit using multiple strategies. Fits with small to negligible errors were obtained using adaptations of the permutation-invariant-polynomials (PIP) approach [2,3] based on neural-networks (PIP-NN) [4,5] and the interpolative moving least squares (IMLS) fitting method [6] (PIP-IMLS). The PESs were used in full-dimensional vibrational calculations with an exact kinetic energy operator by representing the Hamiltonian in a basis of products of contracted bend and stretch functions and using a symmetry adapted Lanczos method to obtain eigenvalues and eigenvectors. Very close agreement with experiment was produced from the purely ab initio PESs. References 1- H.-J. Werner, P. J. Knowles, G. Knizia, 2012.1 ed. 2012, MOLPRO, a package of ab initio programs. see http://www.molpro.net. 2- Z. Xie and J. M. Bowman, J. Chem. Theory Comput 6, 26, 2010. 3- B. J. Braams and J. M. Bowman, Int. Rev. Phys. Chem. 28, 577, 2009. 4- J. Li, B. Jiang and Hua Guo, J. Chem. Phys. 139, 204103 (2013). 5- S Manzhos, X Wang, R Dawes and T Carrington, JPC A 110, 5295 (2006). 6- R. Dawes, X-G Wang, A.W. Jasper and T. Carrington Jr., J. Chem. Phys. 133, 134304 (2010).

  1. A new accurate ground-state potential energy surface of ethylene and predictions for rotational and vibrational energy levels

    Energy Technology Data Exchange (ETDEWEB)

    Delahaye, Thibault, E-mail: thibault.delahaye@univ-reims.fr; Rey, Michaël, E-mail: michael.rey@univ-reims.fr; Tyuterev, Vladimir G. [Groupe de Spectrométrie Moléculaire et Atmosphérique, UMR CNRS 7331, BP 1039, F-51687, Reims Cedex 2 (France); Nikitin, Andrei [Laboratory of Theoretical Spectroscopy, Institute of Atmospheric Optics, Russian Academy of Sciences, 634055 Tomsk, Russia and Quamer, State University of Tomsk (Russian Federation); Szalay, Péter G. [Institute of Chemistry, Eötvös Loránd University, P.O. Box 32, H-1518 Budapest (Hungary)

    2014-09-14

    In this paper we report a new ground state potential energy surface for ethylene (ethene) C{sub 2}H{sub 4} obtained from extended ab initio calculations. The coupled-cluster approach with the perturbative inclusion of the connected triple excitations CCSD(T) and correlation consistent polarized valence basis set cc-pVQZ was employed for computations of electronic ground state energies. The fit of the surface included 82 542 nuclear configurations using sixth order expansion in curvilinear symmetry-adapted coordinates involving 2236 parameters. A good convergence for variationally computed vibrational levels of the C{sub 2}H{sub 4} molecule was obtained with a RMS(Obs.–Calc.) deviation of 2.7 cm{sup −1} for fundamental bands centers and 5.9 cm{sup −1} for vibrational bands up to 7800 cm{sup −1}. Large scale vibrational and rotational calculations for {sup 12}C{sub 2}H{sub 4}, {sup 13}C{sub 2}H{sub 4}, and {sup 12}C{sub 2}D{sub 4} isotopologues were performed using this new surface. Energy levels for J = 20 up to 6000 cm{sup −1} are in a good agreement with observations. This represents a considerable improvement with respect to available global predictions of vibrational levels of {sup 13}C{sub 2}H{sub 4} and {sup 12}C{sub 2}D{sub 4} and rovibrational levels of {sup 12}C{sub 2}H{sub 4}.

  2. Military Specification, Mirror, Front Surfaced Aluminized: For Optical Elements

    Science.gov (United States)

    2007-11-02

    uniform magnesium fluoride or silicon monoxide or as otherwise specified on the applicable drawing. Tha film shall be free from holes, foreign...Mt] «. OATI Of IIMMIMION (YYMHDDt MIL-M-13508C AMENDMENT 1 27 May 1983 MILITARY SPECIFICATION MIRROR, FRONT SURFACED ALUMINIZED : FOR OPTICAL... ALUMINIZED : FOR OPTICAL ELEMENTS This notice should be filed in front of MIL-M-13508C, dated 19 March 1973 MIL-M-13508C dated 19 March 1973 with

  3. Surface-modified gold nanorods for specific cell targeting

    Science.gov (United States)

    Wang, Chan-Ung; Arai, Yoshie; Kim, Insun; Jang, Wonhee; Lee, Seonghyun; Hafner, Jason H.; Jeoung, Eunhee; Jung, Deokho; Kwon, Youngeun

    2012-05-01

    Gold nanoparticles (GNPs) have unique properties that make them highly attractive materials for developing functional reagents for various biomedical applications including photothermal therapy, targeted drug delivery, and molecular imaging. For in vivo applications, GNPs need to be prepared with very little or negligible cytotoxicitiy. Most GNPs are, however, prepared using growth-directing surfactants such as cetyl trimethylammonium bromide (CTAB), which are known to have considerable cytotoxicity. In this paper, we describe an approach to remove CTAB to a non-toxic concentration. We optimized the conditions for surface modification with methoxypolyethylene glycol thiol (mPEG), which replaced CTAB and formed a protective layer on the surface of gold nanorods (GNRs). The cytotoxicities of pristine and surface-modified GNRs were measured in primary human umbilical vein endothelial cells and human cell lines derived from hepatic carcinoma cells, embryonic kidney cells, and thyroid papillary carcinoma cells. Cytotoxicity assays revealed that treating cells with GNRs did not significantly affect cell viability except for thyroid papillary carcinoma cells. Thyroid cancer cells were more susceptible to residual CTAB, so CTAB had to be further removed by dialysis in order to use GNRs for thyroid cell targeting. PEGylated GNRs are further modified to present monoclonal antibodies that recognize a specific surface marker, Na-I symporter, for thyroid cells. Antibody-conjugated GNRs specifically targeted human thyroid cells in vitro.

  4. Specification And Control Of Surface Finish: Empiricism Versus Dogmatism

    Science.gov (United States)

    Stout, K. J.; Obray, C.; Jungles, J.

    1985-06-01

    This paper reviews the development of the analysis of surface finish from the early attempts in the 1930s to the present day. The development of parameters used in surface analysis is shown in context with the instrumental techniques available at the time, and it is argued that characterization based on graphical and experimental convenience has influenced industrial practice. As the requirements of manufacture and functional performance have been stretched by advancing technology, many industrialists have been forced to accept the fact that existing specification practices are limited and have sought alternative descriptions based on well-established techniques; but these techniques themselves are limited, their suitability to in-process measurement being practically nonexistent. It is shown that attempts have been made recently to develop optical methods of assessing surface finish using traditional parameters such as Ra. This paper suggests that it may be time to look toward a new form of specification that is more suited to assessment by optical transducers, and some methods of assessment are proposed. To support this view, a simple low-cost device is discussed that can be calibrated to give Ra but that also presents information in a more relevant empirical way that may be more valid than the existing parameter specification.

  5. A mixed space-time and wavenumber-frequency domain procedure for modelling ground vibration from surface railway tracks

    Science.gov (United States)

    Koroma, S. G.; Thompson, D. J.; Hussein, M. F. M.; Ntotsios, E.

    2017-07-01

    This paper presents a methodology for studying ground vibration in which the railway track is modelled in the space-time domain using the finite element method (FEM) and, for faster computation, discretisation of the ground using either FEM or the boundary element method (BEM) is avoided by modelling it in the wavenumber-frequency domain. The railway track is coupled to the ground through a series of rectangular strips located at the surface of the ground; their vertical interaction is described by a frequency-dependent dynamic stiffness matrix whose elements are represented by discrete lumped parameter models. The effectiveness of this approach is assessed firstly through frequency domain analysis using as excitation a stationary harmonic load applied on the rail. The interaction forces at the ballast/ground interface are calculated using the FE track model in the space-time domain, transformed to the wavenumber domain, and used as input to the ground model for calculating vibration in the free field. Additionally, time domain simulations are also performed with the inclusion of nonlinear track parameters. Results are presented for the coupled track/ground model in terms of time histories and frequency spectra for the track vibration, interaction forces and free-field ground vibration. For the linear track model, the results from the mixed formulation are in excellent agreement with those from a semi-analytical model formulated in the wavenumber-frequency domain, particularly in the vicinity of the loading point. The accuracy of the mixed formulation away from the excitation point depends strongly on the inclusion of through-ground coupling in the lumped parameter model, which has been found to be necessary for both track dynamics and ground vibration predictions.

  6. Classification of the road surface condition on the basis of vibrations of the sprung mass in a passenger car

    Science.gov (United States)

    Prażnowski, K.; Mamala, J.

    2016-09-01

    In order to identify the state of the wheel balance in a passenger car on the basis of vibrations of the car body under actual conditions of its operation, it is necessary to determine the impact of random interferences resulting from a changing environment. For this purpose, the criterion for the evaluation of the road surface condition was developed on the basis of longitudinal vibrations of the car body of the tested car in the speed range from 50 km/h to 110 km/h. Selected functions such as: probability distribution and methods in the frequency domain: short-time Fourier transform (STFT) and power spectral density (PSD) were used to analyse recorded signals.

  7. Nanoporous ultra-high specific surface inorganic fibres

    Science.gov (United States)

    Kanehata, Masaki; Ding, Bin; Shiratori, Seimei

    2007-08-01

    Nanoporous inorganic (silica) nanofibres with ultra-high specific surface have been fabricated by electrospinning the blend solutions of poly(vinyl alcohol) (PVA) and colloidal silica nanoparticles, followed by selective removal of the PVA component. The configurations of the composite and inorganic nanofibres were investigated by changing the average silica particle diameters and the concentrations of colloidal silica particles in polymer solutions. After the removal of PVA by calcination, the fibre shape of pure silica particle assembly was maintained. The nanoporous silica fibres were assembled as a porous membrane with a high surface roughness. From the results of Brunauer-Emmett-Teller (BET) measurements, the BET surface area of inorganic silica nanofibrous membranes was increased with the decrease of the particle diameters. The membrane composed of silica particles with diameters of 15 nm showed the largest BET surface area of 270.3 m2 g-1 and total pore volume of 0.66 cm3 g-1. The physical absorption of methylene blue dye molecules by nanoporous silica membranes was examined using UV-vis spectrometry. Additionally, the porous silica membranes modified with fluoroalkylsilane showed super-hydrophobicity due to their porous structures.

  8. Nanoporous ultra-high specific surface inorganic fibres

    Energy Technology Data Exchange (ETDEWEB)

    Kanehata, Masaki [Faculty of Science and Technology, Keio University, Yokohama 223-8522 (Japan); Ding Bin [Fiber and Polymer Science, University of California, Davis, CA 95616 (United States); Shiratori, Seimei [Faculty of Science and Technology, Keio University, Yokohama 223-8522 (Japan)

    2007-08-08

    Nanoporous inorganic (silica) nanofibres with ultra-high specific surface have been fabricated by electrospinning the blend solutions of poly(vinyl alcohol) (PVA) and colloidal silica nanoparticles, followed by selective removal of the PVA component. The configurations of the composite and inorganic nanofibres were investigated by changing the average silica particle diameters and the concentrations of colloidal silica particles in polymer solutions. After the removal of PVA by calcination, the fibre shape of pure silica particle assembly was maintained. The nanoporous silica fibres were assembled as a porous membrane with a high surface roughness. From the results of Brunauer-Emmett-Teller (BET) measurements, the BET surface area of inorganic silica nanofibrous membranes was increased with the decrease of the particle diameters. The membrane composed of silica particles with diameters of 15 nm showed the largest BET surface area of 270.3 m{sup 2} g{sup -1} and total pore volume of 0.66 cm{sup 3} g{sup -1}. The physical absorption of methylene blue dye molecules by nanoporous silica membranes was examined using UV-vis spectrometry. Additionally, the porous silica membranes modified with fluoroalkylsilane showed super-hydrophobicity due to their porous structures.

  9. Porous structure and specific surface of oil shale

    Energy Technology Data Exchange (ETDEWEB)

    Lopachenok, L.V.; Belyanin, Yu.I.; Proskuryakov, V.A.

    1976-01-01

    The total oil shale pore volume, measured by mercury porometry and benzene picnometry, was 0.157 cu m/g (0.225 cc/cc), with 62% of it made up of 200 to 600 angstrom pores and 3.2% of pores below 31.4 angstroms. The oil shale and kerogen specific surface, measured by low-temperature adsorption of radioactive krypton, decreased from 8.7 to 4.1 sq m/g with increase in the organic matter content from 29 to 97.16%. Crushing in a ball mill changed only the particle external surface and thus did not increase adsorptivity relative to flotation concentration reagents.

  10. The effect of surfaces type on vibration behavior of piezoelectric micro-cantilever close to sample surface in a humid environment based on MCS theory

    Science.gov (United States)

    Korayem, M. H.; Korayem, A. H.

    2016-08-01

    Atomic force microscopy (AFM) has been known as an innovative tool in the fields of surface topography, determination of different mechanical properties and manipulation of particles at the micro- and nanoscales. This paper has been concerned with advanced modeling and dynamic simulation of AFM micro-cantilever (MC) in the amplitude mode in the air environment. To increase the accuracy of the governing equations, modified couple stress theory appropriate in micro- and nanoscales has been utilized based on Timoshenko beam theory in the air environment near the sample surface. Also, to discretize the equations, differential quadrature method has been recommended. In modeling, geometric discontinuities due to the presence of a piezoelectric layer enclosed between two electrode layers and the change in MC cross section when connected to the MC have been considered. In addition to the effect of MC modeling on the accuracy of modeling and vibration amplitude during surface topography, understanding and modeling the environmental forces in the air environment, including van der Waals, capillary and contact forces, are important. This paper has been provided more accurate environmental forces modeling and has been investigated the vibration behavior of piezoelectric MC in the humid environment. Moreover, this paper has been examined the maximum and minimum MC amplitude in the air environment close to the surface with different kinds of topography. The results illustrate that kind of surfaces has effect on the maximum and minimum amplitude due to the decrease or increase in equilibrium MC distance.

  11. Ab initio potential energy surface and vibration-rotation energy levels of silicon dicarbide, SiC2.

    Science.gov (United States)

    Koput, Jacek

    2016-10-01

    The accurate ground-state potential energy surface of silicon dicarbide, SiC2 , has been determined from ab initio calculations using the coupled-cluster approach. Results obtained with the conventional and explicitly correlated coupled-cluster methods were compared. The core-electron correlation, higher-order valence-electron correlation, and scalar relativistic effects were taken into account. The potential energy barrier to the linear SiCC configuration was predicted to be 1782 cm(-1) . The vibration-rotation energy levels of the SiC2 , (29) SiC2 , (30) SiC2 , and SiC(13) C isotopologues were calculated using a variational method. The experimental vibration-rotation energy levels of the main isotopologue were reproduced to high accuracy. In particular, the experimental energy levels of the highly anharmonic vibrational ν3 mode of SiC2 were reproduced to within 6.7 cm(-1) , up to as high as the v3  = 16 state.

  12. Vibrational states of the Pt(111)- $ ≤ft( {sqrt {3} × sqrt {3} } right) $ R30°-K surface structure

    Science.gov (United States)

    Rusina, G. G.; Borisov, S. D.; Eremeev, S. V.; Chulkov, E. V.

    2010-09-01

    Vibrational spectrum of the ordered Pt(111)- left( {sqrt {3} × sqrt {3} } right) R30°- K surface superstructure formed on the platinum surface with adsorption of 1/3 ML potassium is calculated with the use of the interatomic interaction potentials obtained in the strong bond approximation. Relaxation of the surface, dispersion of the surface phonons, local density of vibrational states, and polarization of phonon modes of adatoms and atoms of the substrate are discussed in the work. The theoretical results obtained agree well with the available experimental data.

  13. Study of the Internal Flow and Evaporation Characteristic Inside a Water Droplet on a Vertical Vibrating Hydrophobic Surface

    Energy Technology Data Exchange (ETDEWEB)

    Park, Chang-Seok; Lim, Hee-Chang [Pusan Nat’l Univ., Busan (Korea, Republic of)

    2017-01-15

    Thermal Marangoni flow has been observed inside droplets on heated surfaces, finally resulting in a coffee stain effect. This study aims to visualize and control the thermal Marangoni flow by employing periodic vertical vibration. The variations in the contact angle and internal volume of the droplet as it evaporates is observed by using a combination of continuous light and a still camera. With regard to the internal velocity, the particle image velocimetry system is applied to visualize the internal thermal Marangoni flow. In order to estimate the internal temperature gradient and surface tension on the surface of a droplet, the theoretical model based on the conduction and convection theory of heat transfer is applied. Thus, the internal velocity increases with an increase in plate temperature. The flow directions of the Marangoni and gravitational flows are opposite, and hence, it may be possible to control the coffee stain effect.

  14. Effects of surface finish and treatment on the fatigue behaviour of vibrating cylinder block using frequency response approach

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    This paper presents the effects of surface finish and treatment on the high cycle fatigue behaviour of vibrating cylinder block of a new two-stroke free piston engine at complex variable amplitude loading conditions using frequency response approach,Finite element modelling and frequency response analysis was conducted using finite element analysis software Package MSC.PATRAN/MSC.NASTRAN and fatigue life prediction was carried out using MSC.FATIGUE software. Based on the finite element results, different frequency response approach was applied to predict the cylinder block fatigue life. Results for different load histories and material combinations are also discussed. Results indicated great effects for all surface finish and treatment. It is concluded that polished and cast surface finish conditions give the highest and lowest cylinder block lives, respectively; and that Nitrided treatment leads to longest cylinder block life. The results were used to draw contour plots of fatigue life and damage in the worst or most damaging case.

  15. Effect of surface-specific training on 20-m sprint performance on sand and grass surfaces.

    Science.gov (United States)

    Binnie, Martyn J; Peeling, Peter; Pinnington, Hugh; Landers, Grant; Dawson, Brian

    2013-12-01

    This study compared the effect of an 8-week preseason conditioning program conducted on a sand (SAND) or grass (GRASS) surface on 20-m sprint performance. Twelve team-sport athletes were required to attend three 1-hour training sessions per week, including 2 surface-specific sessions (SAND, n = 6 or GRASS, n = 6) and 1 group session (conducted on grass). Throughout the training period, 20-m sprint times of all athletes were recorded on both sand and grass surfaces at the end of weeks 1, 4, and 8. Results showed a significant improvement in 20-m sand time in the SAND group only (p grass time improved equally in both training subgroups (p grass speed gains when incorporating sand surfaces into a preseason program.

  16. Surface and buried interfacial structures of epoxy resins used as underfills studied by sum frequency generation vibrational spectroscopy.

    Science.gov (United States)

    Vázquez, Anne V; Holden, Brad; Kristalyn, Cornelius; Fuller, Mike; Wilkerson, Brett; Chen, Zhan

    2011-05-01

    Flip chip technology has greatly improved the performance of semiconductor devices, but relies heavily on the performance of epoxy underfill adhesives. Because epoxy underfills are cured in situ in flip chip semiconductor devices, understanding their surface and interfacial structures is critical for understanding their adhesion to various substrates. Here, sum frequency generation (SFG) vibrational spectroscopy was used to study surface and buried interfacial structures of two model epoxy resins used as underfills in flip chip devices, bisphenol A digylcidyl ether (BADGE) and 1,4-butanediol diglycidyl ether (BDDGE). The surface structures of these epoxies were compared before and after cure, and the orientations of their surface functional groups were deduced to understand how surface structural changes during cure may affect adhesion properties. Further, the effect of moisture exposure, a known cause of adhesion failure, on surface structures was studied. It was found that the BADGE surface significantly restructured upon moisture exposure while the BDDGE surface did not, showing that BADGE adhesives may be more prone to moisture-induced delamination. Lastly, although surface structure can give some insight into adhesion, buried interfacial structures more directly correspond to adhesion properties of polymers. SFG was used to study buried interfaces between deuterated polystyrene (d-PS) and the epoxies before and after moisture exposure. It was shown that moisture exposure acted to disorder the buried interfaces, most likely due to swelling. These results correlated with lap shear adhesion testing showing a decrease in adhesion strength after moisture exposure. The presented work showed that surface and interfacial structures can be correlated to adhesive strength and may be helpful in understanding and designing optimized epoxy underfill adhesives.

  17. Vibrational spectra study of phosphorus dendrimer containing azobenzene units on the surface

    Science.gov (United States)

    Furer, V. L.; Vandyukov, A. E.; Majoral, J. P.; Caminade, A. M.; Kovalenko, V. I.

    2013-08-01

    The FTIR and FT Raman spectra of the first generation dendrimers, possessing oxybenzaldehyde (G1) or oxyphenylazobenzaldehyde (G2) terminal groups and sodium 4-[4-oxyphenyl)azo]-benzaldehyde (SOAB) were studied. The structural optimization and normal mode analysis were performed for dendrimer G2 on the basis of the density functional theory (DFT). These calculations gave the frequencies of vibrations, infrared intensities and Raman scattering activities for the E- and Z-forms of azobenzene unit. The energy differences between the E- and Z-forms are 12.62 and 25.16 kcal/mol for SOAB and G2. The calculated in gas phase dipole moments for the E- and Z-forms are equal to 20.86, 18.28 D (SOAB) and 7.56, 8.88 D (G2). The calculated geometrical parameters and harmonic vibrational frequencies are predicted in a good agreement with the experimental data. It was found that dendrimer G2 molecule has a concave lens structure with planar sbnd Osbnd C6H4sbnd CHdbnd Nsbnd N(CH3)Pdbnd S and sbnd Osbnd C6H4sbnd Ndbnd Nsbnd C6H4sbnd CHdbnd O fragments and slightly non-planar cyclotriphosphazene core. The experimental IR and Raman spectra of dendrimer G2 were interpreted by means of potential energy distributions. Relying on DFT calculations a complete vibrational assignment is proposed. The strong band 1598 cm-1 in the IR spectra show marked changes of the optical density in dependence of substituents in the aromatic ring. The differences in the IR and Raman spectra of SOAB and G2 for the E- and Z-forms of azobenzene units were cleared up. During structural isomerization of azobenzene units, redistribution of band intensities appears to a much higher extent than frequency shifts.

  18. Mechanism of bubble detachment from vibrating walls

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dongjun; Park, Jun Kwon, E-mail: junkeun@postech.ac.kr; Kang, Kwan Hyoung [Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH), San 31, Hyoja-dong, Pohang 790-784 (Korea, Republic of); Kang, In Seok [Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), San 31, Hyoja-dong, Pohang 790-784 (Korea, Republic of)

    2013-11-15

    We discovered a previously unobserved mechanism by which air bubbles detach from vibrating walls in glasses containing water. Chaotic oscillation and subsequent water jets appeared when a wall vibrated at greater than a critical level. Wave forms were developed at water-air interface of the bubble by the wall vibration, and water jets were formed when sufficiently grown wave-curvatures were collapsing. Droplets were pinched off from the tip of jets and fell to the surface of the glass. When the solid-air interface at the bubble-wall attachment point was completely covered with water, the bubble detached from the wall. The water jets were mainly generated by subharmonic waves and were generated most vigorously when the wall vibrated at the volume resonant frequency of the bubble. Bubbles of specific size can be removed by adjusting the frequency of the wall's vibration.

  19. Torsion-wagging tunneling and vibrational states in hydrazine determined from its ab initio potential energy surface

    Science.gov (United States)

    Łodyga, Wiesław; Makarewicz, Jan

    2012-05-01

    Geometries, anharmonic vibrations, and torsion-wagging (TW) multiplets of hydrazine and its deuterated species are studied using high-level ab initio methods employing the second-order Møller-Plesset perturbation theory (MP2) as well as the coupled cluster singles and doubles model including connected triple corrections, CCSD(T), in conjunction with extended basis sets containing diffuse and core functions. To describe the splitting patterns caused by tunneling in TW states, the 3D potential energy surface (PES) for the large-amplitude TW modes is constructed. Stationary points in the 3D PES, including equivalent local minima and saddle points are characterized. Using this 3D PES, a flexible Hamiltonian is built numerically and then employed to solve the vibrational problem for TW coupled motion. The calculated ground state rav structure is expected to be more reliable than the experimental one that has been determined using a simplified structural model. The calculated fundamental frequencies allowed resolution of the assignment problems discussed earlier in the literature. The determined energy barriers, including the contributions from the small-amplitude vibrations, to the tunneling of the symmetric and antisymmetric wagging mode of 1997 cm-1 and 3454 cm-1, respectively, are in reasonable agreement with the empirical estimates of 2072 cm-1 and 3312 cm-1, respectively [W. Łodyga et al. J. Mol. Spectrosc. 183, 374 (1997), 10.1006/jmsp.1997.7271]. However, the empirical torsion barrier of 934 cm-1 appears to be overestimated. The ab initio calculations yield two torsion barriers: cis and trans of 744 cm-1 and 2706 cm-1, respectively. The multiplets of the excited torsion states are predicted from the refined 3D PES.

  20. Electromechanical modeling of a honeycomb core integrated vibration energy converter with increased specific power for energy harvesting applications

    Science.gov (United States)

    Chandrasekharan, Nataraj

    Innovation in integrated circuit technology along with improved manufacturing processes has resulted in considerable reduction in power consumption of electromechanical devices. Majority of these devices are currently powered by batteries. However, the issues posed by batteries, including the need for frequent battery recharge/replacement has resulted in a compelling need for alternate energy to achieve self-sufficient device operation or to supplement battery power. Vibration based energy harvesting methods through piezoelectric transduction provides with a promising potential towards replacing or supplementing battery power source. However, current piezoelectric energy harvesters generate low specific power (power-to-weight ratio) when compared to batteries that the harvesters seek to replace or supplement. In this study, the potential of integrating lightweight cellular honeycomb structures with existing piezoelectric device configurations (bimorph) to achieve higher specific power is investigated. It is shown in this study that at low excitation frequency ranges, replacing the solid continuous substrate of a conventional piezoelectric bimorph with honeycomb structures of the same material results in a significant increase in power-to-weight ratio of the piezoelectric harvester. In order to maximize the electrical response of vibration based power harvesters, the natural frequency of these harvesters is designed to match the input driving frequency. The commonly used technique of adding a tip mass is employed to lower the natural frequency (to match driving frequency) of both, solid and honeycomb substrate bimorphs. At higher excitation frequency, the natural frequency of the traditional solid substrate bimorph can only be altered (to match driving frequency) through a change in global geometric design parameters, typically achieved by increasing the thickness of the harvester. As a result, the size of the harvester is increased and can be disadvantageous

  1. Development of Additional Requirements for Inclusion in Military Specification, Sprayable Vibration Damping Material for Surface Vessels

    Science.gov (United States)

    1964-08-05

    8217an’,iegt ’ecn-~nm~m 1 -- 5’ Fuel - 1.0 1o0" ; Lab. Project 9300-16 U. S. Naval Applied Sceince Laboratory Tec:hnical Memorandum #7O Enclosure (1) Page...again, immediately. Per cent weight change shall be computed from the following equation: Per cent weight change f Final--initial weight *. 100 initial 𔃾

  2. Specific nature of Trichomonas vaginalis parasitism of host cell surfaces.

    Science.gov (United States)

    Alderete, J F; Garza, G E

    1985-01-01

    The adherence of Trichomonas vaginalis NYH 286 to host cells was evaluated by using monolayer cultures of HeLa and HEp-2 epithelial cells and human fibroblast cell lines. Saturation of sites on HeLa cells was achieved, yielding a maximal T. vaginalis NYH 286-to-cell ratio of two. The ability of radiolabeled NYH 286 to compete with unlabeled trichomonads for attachment and the time, temperature, and pH-dependent nature of host cell parasitism reinforced the idea of specific parasite-cell associations. Other trichomonal isolates (JH31A, RU375, and JHHR) were also found to adhere to cell monolayers, albeit to different degrees, and all isolates produced maximal contact-dependent HeLa cell cytotoxicity. The avirulent trichomonad, Trichomonas tenax, did not adhere to cell monolayers and did not cause host cell damage. Interestingly, parasite cytadherence was greater with HeLa and HEp-2 epithelial cells than with fibroblast cells. In addition, cytotoxicity with fibroblast cells never exceeded 20% of the level of cell killing observed for epithelial cells. Elucidation of properties of the pathogenic human trichomonads that allowed for host cell surface parasitism was also attempted. Treatment of motile T. vaginalis NYH 286 with trypsin diminished cell parasitism. Incubation of trypsinized organisms in growth medium allowed for regeneration of trichomonal adherence, and cycloheximide inhibited the regeneration of attachment. Organisms poisoned with metronidazole or iodoacetate failed to attach to host cells, and adherent trichomonads exposed to metronidazole or iodoacetate were readily released from parasitized cells. Coincubation experiments with polycationic proteins and sugars and pretreatment of parasites or cells with neuraminidase or periodate had no effect on host cell parasitism. Colchicine and cytochalasin B, however, did produce some inhibition of adherence to HeLa cells. The data suggest that metabolizing T. vaginalis adheres to host cells via parasite surface

  3. THE DIAGNOSTIC SPECIFICATIONS IMPROVEMENT FOR ROLLING STOCK’S TRACTION WITH USING OF DAMPING CONTROL OF VIBRATIONAL ENERGY

    OpenAIRE

    Horobets, V. L.; Snitko, N. P.; A. D. Lashko

    2010-01-01

    In the paper an approximate classification of methods of damping oscillations for complex mechanical systems is offered as well as the approach of an adaptive control by dissipation of the vibration energy of the railway rolling stock devices is presented.

  4. Bound state potential energy surface construction: ab initio zero-point energies and vibrationally averaged rotational constants.

    Science.gov (United States)

    Bettens, Ryan P A

    2003-01-15

    Collins' method of interpolating a potential energy surface (PES) from quantum chemical calculations for reactive systems (Jordan, M. J. T.; Thompson, K. C.; Collins, M. A. J. Chem. Phys. 1995, 102, 5647. Thompson, K. C.; Jordan, M. J. T.; Collins, M. A. J. Chem. Phys. 1998, 108, 8302. Bettens, R. P. A.; Collins, M. A. J. Chem. Phys. 1999, 111, 816) has been applied to a bound state problem. The interpolation method has been combined for the first time with quantum diffusion Monte Carlo calculations to obtain an accurate ground state zero-point energy, the vibrationally average rotational constants, and the vibrationally averaged internal coordinates. In particular, the system studied was fluoromethane using a composite method approximating the QCISD(T)/6-311++G(2df,2p) level of theory. The approach adopted in this work (a) is fully automated, (b) is fully ab initio, (c) includes all nine nuclear degrees of freedom, (d) requires no assumption of the functional form of the PES, (e) possesses the full symmetry of the system, (f) does not involve fitting any parameters of any kind, and (g) is generally applicable to any system amenable to quantum chemical calculations and Collins' interpolation method. The calculated zero-point energy agrees to within 0.2% of its current best estimate. A0 and B0 are within 0.9 and 0.3%, respectively, of experiment.

  5. The origins of intra- and inter-molecular vibrational couplings: A case study of H{sub 2}O-Ar on full and reduced-dimensional potential energy surface

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Dan; Ma, Yong-Tao; Zhang, Xiao-Long; Li, Hui, E-mail: Prof-huili@jlu.edu.cn [Institute of Theoretical Chemistry, Jilin University, 2519 Jiefang Road, Changchun 130023 (China)

    2016-01-07

    The origin and strength of intra- and inter-molecular vibrational coupling is difficult to probe by direct experimental observations. However, explicitly including or not including some specific intramolecular vibrational modes to study intermolecular interaction provides a precise theoretical way to examine the effects of anharmonic coupling between modes. In this work, a full-dimension intra- and inter-molecular ab initio potential energy surface (PES) for H{sub 2}O–Ar, which explicitly incorporates interdependence on the intramolecular (Q{sub 1},  Q{sub 2},  Q{sub 3}) normal-mode coordinates of the H{sub 2}O monomer, has been calculated. In addition, four analytic vibrational-quantum-state-specific PESs are obtained by least-squares fitting vibrationally averaged interaction energies for the (v{sub 1},  v{sub 2},  v{sub 3}) =  (0,  0,  0), (0,  0,  1), (1,  0,  0), (0,  1,  0) states of H{sub 2}O to the three-dimensional Morse/long-range potential function. Each vibrationally averaged PES fitted to 442 points has root-mean-square (rms) deviation smaller than 0.15 cm{sup −1}, and required only 58 parameters. With the 3D PESs of H{sub 2}O–Ar dimer system, we employed the combined radial discrete variable representation/angular finite basis representation method and Lanczos algorithm to calculate rovibrational energy levels. This showed that the resulting vibrationally averaged PESs provide good representations of the experimental infrared data, with rms discrepancies smaller than 0.02 cm{sup −1} for all three rotational branches of the asymmetric stretch fundamental transitions. The infrared band origin shifts associated with three fundamental bands of H{sub 2}O in H{sub 2}O–Ar complex are predicted for the first time and are found to be in good agreement with the (extrapolated) experimental values. Upon introduction of additional intramolecular degrees of freedom into the intermolecular potential energy surface, there is clear

  6. Adsorption and Vibration of O Atoms on Fe Low-index and Fe (211) High-index Surfaces

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The 5-parameter Morse potential(5-MP) of the interaction between oxygen atoms and iron surfaces was constructed. The adsorption and diffusion of O atoms on Fe low-index and Fe(211 ) high-index surfaces were investigated by using 5-MP. All the critical characteristics of the system, such as adsorption site, adsorption geometry, binding energy, and eigenvalues for vibration, were calculated. The calculation results show that O atoms are located at the fourfold hollow site of the Fe(100) surface with an eigenvibration at 437 cm-1. These results are in good agreement with the experimental and theoretical results obtained previously. With regard to the adsorption site of O-Fe(110) system, the authors of this study assume that the preferential adsorption state is the H3 site and not the LB site, which is not in agreement with the experimental inferences obtained earlier. However, on the Fe( 111 ) and Fe(211 ) surfaces,O atoms predominantly occupy the quasi-3-fold site.

  7. Vibrational relaxation dynamics of catalysts on TiO{sub 2} Rutile (1 1 0) single crystal surfaces and anatase nanoporous thin films

    Energy Technology Data Exchange (ETDEWEB)

    Ricks, Allen M.; Anfuso, Chantelle L.; Rodríguez-Córdoba, William; Lian, Tianquan, E-mail: tlian@emory.edu

    2013-08-30

    Highlights: • Investigated vibrational relaxation dynamics of a CO{sub 2}-reduction catalyst on TiO{sub 2} surfaces. • IR pump-vibration sum-frequency generation probe spectroscopy on Rutile (1 1 0) surface. • IR-pump/IR probe transient absorption spectroscopy on nano-crystalline thin films. • CO stretching modes show a ultrafast population equilibration followed by population decay. - Abstract: Time-resolved vibrational sum frequency generation (VSFG) spectroscopy has been used to investigate the vibrational relaxation dynamics of the rhenium bipyridyl CO{sub 2}-reduction catalyst Re(CO){sub 3}Cl(dcbpy) [dcbpy = 4,4′-dicarboxy-2,2′-bipyridine] adsorbed onto the (1 1 0) surface of a Rutile TiO{sub 2} single crystal. IR pump-VSFG probe spectra of the a′(1) CO stretching mode indicate a ultrafast population equilibration between three CO stretching modes followed by their population relaxation via intramolecular vibrational energy transfer. Similar vibational relaxation dynamics was also observed for the same complex on anatase TiO{sub 2} nanocrystalline thin films measured by IR pump-IR probe transient absorption spectroscopy. The relaxation dynamics of ReCOA on TiO{sub 2}, in DMF solution, and immobilized on Au through alkane thiol linkers were compared to examine possible effects of adsorbate-TiO{sub 2} interaction.

  8. The role of vibration in tactile speed perception.

    Science.gov (United States)

    Dallmann, Chris J; Ernst, Marc O; Moscatelli, Alessandro

    2015-12-01

    The relative motion between the surface of an object and our fingers produces patterns of skin deformation such as stretch, indentation, and vibrations. In this study, we hypothesized that motion-induced vibrations are combined with other tactile cues for the discrimination of tactile speed. Specifically, we hypothesized that vibrations provide a critical cue to tactile speed on surfaces lacking individually detectable features like dots or ridges. Thus masking vibrations unrelated to slip motion should impair the discriminability of tactile speed, and the effect should be surface-dependent. To test this hypothesis, we measured the precision of participants in discriminating the speed of moving surfaces having either a fine or a ridged texture, while adding masking vibratory noise in the working range of the fast-adapting mechanoreceptive afferents. Vibratory noise significantly reduced the precision of speed discrimination, and the effect was much stronger on the fine-textured than on the ridged surface. On both surfaces, masking vibrations at intermediate frequencies of 64 Hz (65-μm peak-to-peak amplitude) and 128 Hz (10 μm) had the strongest effect, followed by high-frequency vibrations of 256 Hz (1 μm) and low-frequency vibrations of 32 Hz (50 and 25 μm). These results are consistent with our hypothesis that slip-induced vibrations concur to the discrimination of tactile speed.

  9. Passive Optical Technique to Measure Physical Properties of a Vibrating Surface

    Science.gov (United States)

    2014-01-01

    was 25 megapascals, but the brief time produced only a small surface wave that propagated away from the point of impact. Sequence left to right are...optics treatise on reflectance, and defined relevant essentials of reflectance, first introducing the term bidirectional reflectance distribution...chosen to match the spatial extent of the data, ω=2π/λ is the frequency of the surface wave , λ is the wavelength of the surface wave , and ft is the time

  10. Analysis of structure and vibrational dynamics of the BeTe(001) surface using X-ray diffraction, Raman spectroscopy, and density functional theory

    DEFF Research Database (Denmark)

    Kumpf, C.; Müller, A.; Weigand, W.;

    2003-01-01

    The atomic structure and lattice dynamics of epitaxial BeTe(001) thin films are derived from surface x-ray diffraction and Raman spectroscopy. On the Te-rich BeTe(001) surface [1 (1) over bar0]-oriented Te dimers are identified. They cause a (2 X 1) superstructure and induce a pronounced buckling...... in the underlying Te layer. The Be-rich surface exhibits a (4 X 1) periodicity with alternating Te dimers and Te-Be-Te trimers. A vibration eigenfrequency of 165 cm(-1) is observed for the Te-rich surface, while eigenmodes at 157 and 188 cm(-1) are found for the Be-rich surface. The experimentally derived atomic...... geometry and the vibration modes are in very good agreement with the results of density functional theory calculations....

  11. Nonlinear vibration of viscoelastic embedded-DWCNTs integrated with piezoelectric layers-conveying viscous fluid considering surface effects

    Science.gov (United States)

    Fereidoon, A.; Andalib, E.; Mirafzal, A.

    2016-07-01

    This article studies the nonlinear vibration of viscoelastic embedded nano-sandwich structures containing of a double walled carbon nanotube (DWCNT) integrated with two piezoelectric Zinc oxide (ZnO) layers. DWCNT and ZnO layers are subjected to magnetic and electric fields, respectively. This system is conveying viscous fluid and the related force is calculated by modified Navier-Stokes relation considering slip boundary condition and Knudsen number. Visco-Pasternak model with three parameters of the Winkler modulus, shear modulus, and damp coefficient is used for simulation of viscoelastic medium. The nano-structure is simulated as an orthotropic Timoshenko beam (TB) and the effects of small scale, structural damping and surface stress are considered based on Eringen's, Kelvin-voigt and Gurtin-Murdoch theories. Energy method and Hamilton's principle are employed to derive motion equations which are then solved using differential quadrature method (DQM). The detailed parametric study is conducted, focusing on the combined effects of small scale effect, fluid velocity, thickness of piezoelectric layer, boundary condition, surface effects, van der Waals (vdW) force on the frequency and critical velocity of nano-structure. Results indicate that the frequency and critical velocity increases with assume of surface effects.

  12. Vibration analysis of a rectangular thin isotropic plate with a part-through surface crack of arbitrary orientation and position

    Science.gov (United States)

    Bose, Tanmoy; Mohanty, A. R.

    2013-12-01

    In this paper, vibration analysis of a rectangular thin isotropic plate with a part-through surface crack of arbitrary orientation and position is performed by using the Kirchhoff plate theory. Simply supported (SSSS), clamped (CCCC) and simply supported-clamped (SCSC) boundary conditions are considered for the analysis. First, the governing differential equation of a cracked plate is formulated. A modified line spring model is then used to formulate the crack terms in the governing equation. Next, by the application of Burger's formulation, the differential equation is transformed into the well-known Duffing equation with cubic and quadratic nonlinearities. The Duffing equation is then solved by the method of multiple scales (MMS) to extract the frequency response curve. Natural frequencies are evaluated for different values of length, angle and position of a part-through surface crack. Some results are compared with the published literature. Amplitude variation with different values of length, angle and position of a part-through surface crack are presented, for all three types of the plate boundary conditions.

  13. Vibration reliability analysis for aeroengine compressor blade based on support vector machine response surface method

    Institute of Scientific and Technical Information of China (English)

    GAO Hai-feng; BAI Guang-chen

    2015-01-01

    To ameliorate reliability analysis efficiency for aeroengine components, such as compressor blade, support vector machine response surface method (SRSM) is proposed. SRSM integrates the advantages of support vector machine (SVM) and traditional response surface method (RSM), and utilizes experimental samples to construct a suitable response surface function (RSF) to replace the complicated and abstract finite element model. Moreover, the randomness of material parameters, structural dimension and operating condition are considered during extracting data so that the response surface function is more agreeable to the practical model. The results indicate that based on the same experimental data, SRSM has come closer than RSM reliability to approximating Monte Carlo method (MCM); while SRSM (17.296 s) needs far less running time than MCM (10958 s) and RSM (9840 s). Therefore, under the same simulation conditions, SRSM has the largest analysis efficiency, and can be considered a feasible and valid method to analyze structural reliability.

  14. Axial buckling and transverse vibration of ultrathin nanowires: low symmetry and surface elastic effect

    Science.gov (United States)

    Lei, Xiao; Narsu, B.; Yun, Guohong; Li, Jiangang; Yao, Haiyan

    2016-05-01

    Surface effects play a deterministic role in the physical and mechanical properties of nanosized materials and structures. In this paper, we present a self-consistent theoretical scheme for describing the elasticity of nanowires. The natural frequency and the critical compression force of axial buckling are obtained analytically, taking into consideration the influences of lower symmetry, additional elastic parameters, surface reconstruction, surface elasticity, and residual surface stress. Applications of the present theory to elastic systems for the    axially oriented Si and Cu nanowires and Ag    axially oriented nanowires yield good agreement with experimental data and calculated results. The larger positive value of the new elastic parameter c12α taken into account for Si    oriented nanowires drives the curves of natural frequency and critical compression force versus thickness towards the results obtained from density functional theory simulation. Negative surface stress decreases the critical load for axial buckling, thus making the nanowires very easy to bend into various structures. The present study is envisaged to provide useful insights for the design and application of nanowire-based devices.

  15. Surface-catalyzed recombination into excited electronic, vibrational, rotational, and kinetic energy states: A review

    Science.gov (United States)

    Kofsky, I. L.; Barrett, J. L.

    1985-01-01

    Laboratory experiments in which recombined CO, CO2, D2O, OH, N2, H2, and O2 molecules desorb from surfaces in excited internal and translational states are briefly reviewed. Unequilibrated distributions predominate from the principally catalytic metal substrates so far investigated. Mean kinetic energies have been observed up to approx. 3x, and in some cases less than, wall-thermal; the velocity distributions generally vary with emission angle, with non-Lambertian particle fluxes. The excitation state populations are found to depend on surface impurities, in an as yet unexplained way.

  16. Ab initio characterization of low-lying triplet state potential-energy surfaces and vibrational frequencies in the Wulf band of ozone

    Science.gov (United States)

    Xie, Daiqian; Guo, Hua; Peterson, Kirk A.

    2001-12-01

    Accurate ab initio potential-energy surfaces of the 3A2 and 3B1 states of ozone and their nonadiabatic coupling are reported near the ground-state equilibrium geometry using an internally contracted multireference configuration interaction method. These coupled three-dimensional potential-energy surfaces enable the first theoretical characterization of all three vibrational modes in the Wulf band. Reasonably good agreement with recent experimental observations is obtained.

  17. Experimental study of the Marangoni flow in evaporating water droplet placed on vertical vibration and heated hydrophobic surface

    Science.gov (United States)

    Park, Chang Seok; Lim, Hee Chang

    2015-11-01

    In general, the heated surface generates a Marangoni flow inside a droplet yielding a coffee stain effect in the end. This study aims to visualize and control the Marangoni flow by using periodic vertical vibration. While the droplet is evaporating, the variation of contact angle and internal volume of droplet was observed by using the combination of a continuous light and a DSLR still camera. Regarding the internal velocity, the PIV(Particle Image Velocimetry) system was applied to visualize the internal Marangoni flow. In order to estimate the temperature gradient inside and surface tension on the droplet, a commercial software Comsol Multiphysics was used. In the result, the internal velocity increases with the increase of the plate temperature and both flow directions of Marangoni and gravitational flow are opposite so that there seems to be a possibility to control the coffee stain effect. In addition, the Marangoni flow was controlled at relatively lower range of frequency 30 ~ 50Hz. Work supported by Korea government Ministry of Trade, Industry and Energy KETEP grant No. 20134030200290, Ministry of Education NRF grant No. NRF2013R1A1A2005347.

  18. Ab initio potential energy surface and excited vibrational states for the electronic ground state of Li2H

    Institute of Scientific and Technical Information of China (English)

    鄢国森; 先晖; 谢代前

    1997-01-01

    A 285-pomt multi-reference configuration-interaction involving single and double excitations ( MRS DCI) potential energy surface for the electronic ground state of L12H is determined by using 6-311G (2df,2pd)basis set.A Simons-Parr-Finlan polynomial expansion is used to fit the discrete surface with a x2 of 4.64×106 The equn librium geometry occurs at Rc=0.172 nm and,LiHL1=94.10°.The dissociation energy for reaction I2H(2A)→L12(1∑g)+H(2S) is 243.910 kJ/mol,and that for reaction L12H(2A’)→HL1(1∑) + L1(2S) is 106.445 kl/mol The inversion barrier height is 50.388 kj/mol.The vibrational energy levels are calculated using the discrete variable representation (DVR) method.

  19. Investigations of influence of vibration smoothing conditions of geometrical structure on machined surfaces

    Science.gov (United States)

    Bańkowski, D.; Spadło, S.

    2017-02-01

    The paper presents influence of the type of abrasive media on the operating parameters of the surface of components made of composite ceramic-glass, coated with a layer of antiferromagnetic. The research presents the possibilities offered by the use of resin bonded media with different intensities abrasive, understood as different content of abrasive grains. There were used Rollwasch smoothing media PB series – resin plastic media. Media were cone-shaped, with different abrasive properties (10%, 50% and 85%). The process was carried out by using chemical compounds - liquid supportive ME series L100 A22 / NF. Attention has also been given to the relation between the properties of abrasive media and surfaces that can be obtained after polishing with porcelain media and deburring with resin bonded media. As the output surface used the disc of hard drive. Then, to analysis of the possibility various kinds of abrasive media in vibratory finishing the analysis of surface texture with an optical profilometer Talysurf CCI Lite - Taylor Hobson were done. As a result of the effects polishing and deburring using vibratory finishing were compared.

  20. Rate of evolution of the specific surface area of surface snow layers.

    Science.gov (United States)

    Cabanes, Axel; Legagneux, Loïc; Dominé, Florent

    2003-02-15

    The snowpack can impact atmospheric chemistry by exchanging adsorbed or dissolved gases with the atmosphere. Modeling this impact requires the knowledge of the specific surface area (SSA) of snow and its variations with time. We have therefore measured the evolution of the SSA of eight recent surface snow layers in the Arctic and the French Alps, using CH4 adsorption at liquid nitrogen temperature (77 K). The SSA of fresh snow layers was found to decrease with time, from initial values in the range 613-1540 cm2/g to values as low as 257 cm2/g after 6 days. This is explained by snow metamorphism, which causes modifications in crystal shapes, here essentially crystal rounding and the disappearance of microstructures. A parametrization of the rate of SSA decrease is proposed. We fit the SSA decrease to an exponential law and find that the time constant alpha(exp) (day(-1)) depends on temperature according to alpha(exp) = 76.6 exp (-1708/7), with Tin kelvin. Our parametrization predicts that the SSA of a snow layer evolving at -40 degrees C will decrease by a factor of 2 after 14 days, while a similar decrease at -1 degrees C will only require 5 days. Wind was found to increase the rate of SSA decrease, but insufficient data did not allow a parametrization of this effect.

  1. Vibrational Fingerprints of Low-Lying PtnP2n (n = 1–5) Cluster Structures from Global Optimization Based on Density Functional Theory Potential Energy Surfaces

    KAUST Repository

    Jedidi, Abdesslem

    2015-11-13

    Vibrational fingerprints of small PtnP2n (n = 1–5) clusters were computed from their low-lying structures located from a global exploration of their DFT potential energy surfaces with the GSAM code. Five DFT methods were assessed from the CCSD(T) wavenumbers of PtP2 species and CCSD relative energies of Pt2P4 structures. The eight first PtnP2n isomers found are reported. The vibrational computations reveal (i) the absence of clear signatures made by overtone or combination bands due to very weak mechanical and electrical anharmonicities and (ii) some significant and recurrent vibrational fingerprints in correlation with the different PP bonding situations in the PtnP2n structures.

  2. Specifics of surface runoff contents and treatment in large cities

    Directory of Open Access Journals (Sweden)

    V.N. Chechevichkin

    2014-10-01

    Full Text Available The degree of surface runoff pollution in large cities has been assessed in modern conditions in the case study of production sites of St. Petersburg. Increased content of petroleum derivatives and heavy metal ions both in rainwater runoff and especially in snowmelt runoff has been revealed. It has been established that the composition of infiltration runoff from the newly built-up sites within the city limits commonly depends on their background, especially in the places of former unauthorized dumps, which are usually buried under the building sites. The content of petroleum derivatives in such surface runoff can exceed significantly their content in the runoff of landfills. Most petroleum derivatives appear in the surface runoff as emulsified and associated with suspended matters forms, which are a source of secondary pollution of waste water as it is accumulated in settlers and traps of local waste water treatment plants. Filtrational-sorptive technologies of surface runoff treatment are the most effective and simple in terms of both treatment and waste disposal.

  3. Mode-specific multi-channel dynamics of the F- + CHD2Cl reaction on a global ab initio potential energy surface

    Science.gov (United States)

    Szabó, István; Czakó, Gábor

    2016-10-01

    We report a detailed quasiclassical trajectory study for the dynamics of the ground-state and CH/CD stretching-excited F- + CHD2Cl(vCH/CD = 0, 1) → Cl- + CHD2F, HF + CD2Cl-, and DF + CHDCl- SN2, proton-, and deuteron-abstraction reactions using a full-dimensional global ab initio analytical potential energy surface. The simulations show that (a) CHD2Cl(vCH/CD = 1), especially for vCH = 1, maintains its mode-specific excited character prior to interaction, (b) the SN2 reaction is vibrationally mode-specific, (c) double inversion can occur and is enhanced upon CH/CD stretching excitations, (d) in the abstraction reactions the HF channel is preferred and the vCH/CD = 1 excitations significantly promote the HF/DF channels, (e) back-side rebound, back-side stripping, and front-side stripping are the dominant direct abstraction mechanisms based on correlated scattering- and attack-angle distributions, (f) the exact classical vibrational energy-based Gaussian binning (1GB) provides realistic mode-specific polyatomic product state distributions, (g) in the abstraction reactions CH and CD stretchings are not pure spectator modes and mainly ground-state products are produced, thus most of the initial energy transfers into product translation, and (h) the HF and DF product molecules are rotationally cold without any significant dependence on the reactant's and HF/DF vibrational states.

  4. Manganese Dioxide with High Specific Surface Area for Alkaline Battery

    Institute of Scientific and Technical Information of China (English)

    HUANG You-ju; LIN Yu-li; LI Wei-shan

    2012-01-01

    The authors reported a facile method for the synthesis of manganese dioxide without any template and catalyst at a low-temperature.The prepared sample was characterized with X-ray diffraction(XRD),scanning electron microscopy(SEM),Brunauer-Emmett-Teller(BET) surface analysis,Fourier transform infrared(FTIR) spectrometry,cyclic voltammetry,altemative current(AC) impedance test and battery discharge test.It is found that the prepared sample belongs to α-MnO2 and has a microsphere morphology and a large BET surface area.The electrochemical characterization indicates that the prepared sample displays a larger electrochemical capacitance than the commercial electrolytic manganese dioxides(EMD) in Na2SO4 solution,and exhibits larger discharge capacity than EMD,especially at a high rate discharge condition when it is used as cathode of alkaline Zn/MnO2 battery.

  5. Crack modelling and detection in Timoshenko FGM beam under transverse vibration using frequency contour and response surface model with GA

    Science.gov (United States)

    Banerjee, Amit; Panigrahi, Brajesh; Pohit, G.

    2016-04-01

    In the present work, dynamic response of cracked Timoshenko beam with functionally graded material properties are obtained by a numerical technique using Ritz approximation. In order to verify the applicability and performance of the formulation, comparisons of the present numerical method with three-dimensional FEM models are made. Crack is assumed to be transverse and open throughout the vibration cycle. Two different crack detection techniques have been proposed. Results obtained by the numerical technique are used in both of the crack detection techniques. In the first technique, the frequency contours with respect to crack location and size are plotted and the intersection of contours of different modes helps in the prediction of crack location and size. In the second technique, crack is modelled using response surface methodology (RSM). The sum of the squared errors between the numerical and RSM regression model natural frequencies is used as the objective function. This objective function is minimised using genetic algorithm optimisation technique. Both the crack detection techniques and the numerical analysis have shown good agreement with each other.

  6. Arc-Surfaced Frictional Damper for Vibration Control in Container Crane

    Directory of Open Access Journals (Sweden)

    Gongxian Wang

    2017-01-01

    Full Text Available In this paper, a new arc-surfaced frictional damper (AFD is proposed and its hysteretic behavior is experimentally studied. Then the device is applied to container crane based on a seesaw mechanism. The major advantage of the seesaw damping system is that the long tension cables can be utilized as bracing between the seesaw member and the portal legs to avoid compression and buckling of the cables. A simplified trilinear force-displacement model on the basis of experimental results is adopted to represent the hysteretic behavior of AFD. After that, seismic responses of container crane with and without dampers to four earthquakes are studied using nonlinear dynamic time-history analysis. Besides this system, a diagonal-brace-AFD system is studied for comparison. A method based on the displacement and energy dissipation ratio is proposed to find the optimum slip force for seesaw damping system. Performance of AFD control system is assessed though various parameters including displacement and maximum portal frame drift angle. Results prove a feasible application of AFD control system to absorb large amounts of seismic energy and significantly reduce the structural responses.

  7. A refined integro-surface energy-based model for vibration of magnetically actuated double-nanowire-systems carrying electric current

    Science.gov (United States)

    Kiani, Keivan

    2017-02-01

    A novel surface energy-based model is developed to examine more precisely vibrations of current-carrying double-nanowire-systems immersed in a longitudinal magnetic field. Using Biot-Savart and Lorentz laws, a more refined version of interwire interactional magnetic forces is presented. By employing Rayleigh beam theory, the equations of motion are derived. In fact, these are coupled integro-differential equations which are more accurate with respect to those of the previously developed models. For simply supported and clamped nanosystems, governing equations are analyzed via assumed mode method. The effects of interwire distance, slenderness ratio, electric current, magnetic field strength, and surface effect on the fundamental frequency are addressed carefully. The obtained results display the importance of exploiting the refined model for vibration analysis of nanosystems with low interwire distance, high electric current, and high magnetic field strength.

  8. [Study on Enhancing Characteristic Vibration of the Molecular Vibration Spectrum for BDE-15 Based on Solvent Effect].

    Science.gov (United States)

    Jiang, Long; Meng, Chong; Li, Yu

    2015-12-01

    In this paper, the molecular vibrational spectra (IR spectra and Raman spectra) of 4, 4'-dibrominated diphenyl ethers (BDE-15) in atmosphere and 24 kinds of solvents were calculated, at the B3LYP/6-31+G(d) level by density functional theory and self-consistent reaction field separately. Taking the spectra in atmosphere as benchmark, the spectra information of selected characteristic vibrations which were sensitive to the polarity of solvent were used to establish the solvent effect index system for BDE-15, evaluate the specific solvent effect on vibrational frequency, IR vibrational intensity, Raman vibrational intensity and comprehensive solvent effect of each solvent and search the organic solvent which significantly affected the frequency shift/intensity. From the view of molecular vibrational frequency, the characteristic vibrations sensitive to polarity of solvent (frequency shift > 1 cm⁻¹) are all correlated with stretching and out-surface bending vibrations, the solvent effect on the vibrational frequency of BDE-15 of 24 kinds of solvents are all insignificant, with the index values between 1.01-1.03, compared with standard index value 1 of atmosphere spectra. From the view of molecular vibrational intensity, 24 kinds of solvents have all strengthen the vibrational intensities of most of vibrations, locating at the high frequency region of Raman spectra and the middle/low frequency region of IR spectra. The solvents which enhance the vibrational intensities significantly (index value greater than 6 and 5 for IR and Raman intensity separately) include alcohols, acetonitrile, dimethyl sulfoxide, nitrobenzene, dimethyl sulfoxide. The solvent effect index values on Raman vibrational intensity of BDE-15 increase along with the dielectric constant of solvents from linear to logarithmic growth trend, while the solvent effect index values on IR vibrational intensity only leaving the linear relationship. The comprehensive solvent effect index values have presented

  9. Vibrationally specific photoionization cross sections of acrolein leading to the Χ{sup ~}A{sup '} ionic state

    Energy Technology Data Exchange (ETDEWEB)

    López-Domínguez, Jesús A.; Lucchese, Robert R., E-mail: lucchese@mail.chem.tamu.edu [Department of Chemistry, Texas A and M University, College Station, Texas 77843-3255 (United States); Fulfer, K. D.; Hardy, David; Poliakoff, E. D. [Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803 (United States); Aguilar, A. A. [Advanced Light Source, Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720 (United States)

    2014-09-07

    The vibrational branching ratios in the photoionization of acrolein for ionization leading to the Χ{sup ~}A{sup '} ion state were studied. Computed logarithmic derivatives of the cross section and the corresponding experimental data derived from measured vibrational branching ratios for several normal modes (ν{sub 9}, ν{sub 10}, ν{sub 11}, and ν{sub 12}) were found to be in relatively good agreement, particularly for the lower half of the 11–100 eV photon energy range considered. Two shape resonances have been found near photon energies of 15.5 and 23 eV in the photoionization cross section and have been demonstrated to originate from the partial cross section of the A{sup ′} scattering symmetry. The wave functions computed at the resonance complex energies are delocalized over the whole molecule. By looking at the dependence of the cross section on the different normal mode displacements together with the wave function at the resonant energy, a qualitative explanation is given for the change of the cross sections with respect to changing geometry.

  10. Vibrationally specific photoionization cross sections of acrolein leading to the tilde{X} {}^2 A^' } ionic state

    Science.gov (United States)

    López-Domínguez, Jesús A.; Lucchese, Robert R.; Fulfer, K. D.; Hardy, David; Poliakoff, E. D.; Aguilar, A. A.

    2014-09-01

    The vibrational branching ratios in the photoionization of acrolein for ionization leading to the tilde{X} {}^2 A^' } ion state were studied. Computed logarithmic derivatives of the cross section and the corresponding experimental data derived from measured vibrational branching ratios for several normal modes (ν9, ν10, ν11, and ν12) were found to be in relatively good agreement, particularly for the lower half of the 11-100 eV photon energy range considered. Two shape resonances have been found near photon energies of 15.5 and 23 eV in the photoionization cross section and have been demonstrated to originate from the partial cross section of the A' scattering symmetry. The wave functions computed at the resonance complex energies are delocalized over the whole molecule. By looking at the dependence of the cross section on the different normal mode displacements together with the wave function at the resonant energy, a qualitative explanation is given for the change of the cross sections with respect to changing geometry.

  11. The giant frequency shift of intramolecular O-H vibration band in the raman spectra of water on the silver surface

    CERN Document Server

    Kompan, Mikhail

    2016-01-01

    The giant frequency shift was observed in Raman spectra for inramolecular O-H vibration band. The effect was observed in SERS-condition experiment, when exciting light was focused by short-focus objective on the Ag-surface, merged in water. The shift was detected relatively to the regularl position of band, measured from the bulk of water under the same other conditions.

  12. [The study of dimethoate by means of vibrational and surface enhanced Raman spectroscopy on Au/Ag core-shell nanoparticles].

    Science.gov (United States)

    He, Qiang; Li, Si; Yu, Dan-Ni; Zhou, Gunag-Ming; Ji, Fang-Ying; Subklew, Guenter

    2010-12-01

    The vibrational structure of dimethoate, with its solid state and saturated solutions at acidic and basic conditions, was characterized with combination of means of FTIR and FT-Raman vibrational spectroscopy technology, and the comprehensive information about the dimethoate molecular groups' vibrational features was obtained. The surface enhanced Raman scattering (SERS) spectra of dimethoate at different concentrations with different acidic and basic conditions, and adsorbed on the substrate's surface of the core-shell Au/Ag nanoparticles, were also obtained. The adsorption states of dimethoate's molecule on the substrate's surface of the core-shell Au/Ag nanoparticles and the effects by the different acid-base conditions were investigated, with speculation of the adsorption mechanism. From the results, v(as)(NH), v(as)(CH3), v(O=C-N), tau(O=C-N), v(P-O), v(P=S), v(C-C) and delta(P-O-C) are the characteristic peaks of inner dimethoate structure's vibrations; and the concentration range in which dimethoate could interact with core-shell Au/Ag nanoparticles fully is about 1.0 x 10(-3) mol * L(-1) both in acidic and basic conditions. Dimethoate's molecule interacts with SERS' substrate surface mainly through P-O-C, O=C-C, (S-CH2), P=S, and CH3 structures; and the effects of dimethoate's hydrolysis path in acidic and basic conditions on the adsorption are discussed, which give some good references for the research of organophosphorus pesticides' transformations in different environmental systems.

  13. Specification of the Surface Charging Environment with SHIELDS

    Science.gov (United States)

    Jordanova, V.; Delzanno, G. L.; Henderson, M. G.; Godinez, H. C.; Jeffery, C. A.; Lawrence, E. C.; Meierbachtol, C.; Moulton, J. D.; Vernon, L.; Woodroffe, J. R.; Brito, T.; Toth, G.; Welling, D. T.; Yu, Y.; Albert, J.; Birn, J.; Borovsky, J.; Denton, M.; Horne, R. B.; Lemon, C.; Markidis, S.; Thomsen, M. F.; Young, S. L.

    2016-12-01

    Predicting variations in the near-Earth space environment that can lead to spacecraft damage and failure, i.e. "space weather", remains a big space physics challenge. A recently funded project through the Los Alamos National Laboratory (LANL) Directed Research and Development (LDRD) program aims at developing a new capability to understand, model, and predict Space Hazards Induced near Earth by Large Dynamic Storms, the SHIELDS framework. The project goals are to understand the dynamics of the surface charging environment (SCE), the hot (keV) electrons representing the source and seed populations for the radiation belts, on both macro- and microscale. Important physics questions related to rapid particle injection and acceleration associated with magnetospheric storms and substorms as well as plasma waves are investigated. These challenging problems are addressed using a team of world-class experts in the fields of space science and computational plasma physics, and state-of-the-art models and computational facilities. In addition to physics-based models (like RAM-SCB, BATS-R-US, and iPIC3D), new data assimilation techniques employing data from LANL instruments on the Van Allen Probes and geosynchronous satellites are developed. Simulations with the SHIELDS framework of the near-Earth space environment where operational satellites reside are presented. Further model development and the organization of a "Spacecraft Charging Environment Challenge" by the SHIELDS project at LANL in collaboration with the NSF Geospace Environment Modeling (GEM) Workshop and the multi-agency Community Coordinated Modeling Center (CCMC) to assess the accuracy of SCE predictions are discussed.

  14. Snow specific surface area simulation using the one-layer snow model in the Canadian LAnd Surface Scheme (CLASS)

    OpenAIRE

    2013-01-01

    Snow grain size is a key parameter for modeling microwave snow emission properties and the surface energy balance because of its influence on the snow albedo, thermal conductivity and diffusivity. A model of the specific surface area (SSA) of snow was implemented in the one-layer snow model in the Canadian LAnd Surface Scheme (CLASS) version 3.4. This offline multilayer model (CLASS-SSA) simulates the decrease of SSA based on snow age, snow temperature and t...

  15. Study on Effect of Ultrasonic Vibration on Grinding Force and Surface Quality in Ultrasonic Assisted Micro End Grinding of Silica Glass

    Directory of Open Access Journals (Sweden)

    Zhang Jianhua

    2014-01-01

    Full Text Available Ultrasonic vibration assisted micro end grinding (UAMEG is a promising processing method for micro parts made of hard and brittle materials. First, the influence of ultrasonic assistance on the mechanism of this processing technology is theoretically analyzed. Then, in order to reveal the effects of ultrasonic vibration and grinding parameters on grinding forces and surface quality, contrast grinding tests of silica glass with and without ultrasonic assistance using micro radial electroplated diamond wheel are conducted. The grinding forces are measured using a three-component dynamometer. The surface characteristics are detected using the scanning electron microscope. The experiment results demonstrate that grinding forces are significantly reduced by introducing ultrasonic vibration into conventional micro end grinding (CMEG of silica glass; ultrasonic assistance causes inhibiting effect on variation percentages of tangential grinding force with grinding parameters; ductile machining is easier to be achieved and surface quality is obviously improved due to ultrasonic assistance in UAMEG. Therefore, larger grinding depth and feed rate adopted in UAMEG can lead to the improvement of removal rate and machining efficiency compared with CMEG.

  16. 利用Kinect传感器获取振动表面的四维振动数据%The four-dimensional vibration data obtaining on vibrating surfaces by Kinect sensor

    Institute of Scientific and Technical Information of China (English)

    严慧敏; 何炳蔚

    2015-01-01

    The main weaknesses of traditional vibration measurement are that the limit measurement posi‐tions ,low dimensions and with high cost .In this paper ,the speckle ranging technique principle and sam‐pling frequency applied into real‐time four‐dimensional measurement approach have been studied to obtain information from the surfaces of vibrating objects by using Kinect sensor .It can quickly obtain the meas‐urement with four‐dimensional information on the surface with lower cost .Through the measurement test , and by the comparison to different data measured by Kinect sensor and force sensor in different frequen‐cies ,the results show that Kinect sensor can be used in low‐frequency vibration measurement .%针对目前大多数振动测量方法存在测点数量有限、维度底、成本高的问题,基于Kinect传感器的散斑测距技术原理和采样频率,研究将其应用于实时测量振动物体表面所有点的振动信息,实现高维、全域、低成本的振动测量。通过测量实验,比较不同频率下Kinect传感器和力传感器测得的数据,结果表明了Ki‐nect设备用于低频振动测量的可行性。

  17. Structure-based sampling and self-correcting machine learning for accurate calculations of potential energy surfaces and vibrational levels

    Science.gov (United States)

    Dral, Pavlo O.; Owens, Alec; Yurchenko, Sergei N.; Thiel, Walter

    2017-06-01

    We present an efficient approach for generating highly accurate molecular potential energy surfaces (PESs) using self-correcting, kernel ridge regression (KRR) based machine learning (ML). We introduce structure-based sampling to automatically assign nuclear configurations from a pre-defined grid to the training and prediction sets, respectively. Accurate high-level ab initio energies are required only for the points in the training set, while the energies for the remaining points are provided by the ML model with negligible computational cost. The proposed sampling procedure is shown to be superior to random sampling and also eliminates the need for training several ML models. Self-correcting machine learning has been implemented such that each additional layer corrects errors from the previous layer. The performance of our approach is demonstrated in a case study on a published high-level ab initio PES of methyl chloride with 44 819 points. The ML model is trained on sets of different sizes and then used to predict the energies for tens of thousands of nuclear configurations within seconds. The resulting datasets are utilized in variational calculations of the vibrational energy levels of CH3Cl. By using both structure-based sampling and self-correction, the size of the training set can be kept small (e.g., 10% of the points) without any significant loss of accuracy. In ab initio rovibrational spectroscopy, it is thus possible to reduce the number of computationally costly electronic structure calculations through structure-based sampling and self-correcting KRR-based machine learning by up to 90%.

  18. Crystal structure, Hirshfeld surface analysis, vibrational, thermal behavior and UV spectroscopy of (2,6-diaminopyridinium) dihydrogen arsenate

    Science.gov (United States)

    Bouaziz, Emna; Ben Hassen, Chawki; Chniba-Boudjada, Nassira; Daoud, Abdelaziz; Mhiri, Tahar; Boujelbene, Mohamed

    2017-10-01

    A new organic dihydrogenomonoarsenate (C5H8N3)H2AsO4 was synthesized by slow evaporation method at room temperature and characterized by X-ray single crystal diffraction. This compound crystallizes in the monoclinic system with the centro-symmetric space group P21/n. Unit cell parameters are a = 10.124 (5)Ǻ, b = 6.648 (5)Ǻ, c = 13.900 (5)Ǻ, β = 105.532° with Z = 4. The crystal structure was solved and refined to R = 0.038 with 2001 independent reflections. Hirshfeld surfaces analysis were used to visualize the fidelity of the crystal structure which has been determined by X-ray data collection on single crystals (C5H8N3)H2AsO4. Due the strong hydrogen Osbnd H⋯O bond network connecting the H2AsO4 groups, the anionic arrangement must be described as infinite (H2AsO4)nn-of dimers chains spreading, in a zig zag fashion, parallel to the b direction. The organic groups (C5H8N3)+ are anchored between adjacent polyanions through multiple hydrogen bonds Nsbnd H⋯O. The thermal decomposition of precursors studied by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), indicate the existence of two mass loss regions correspond to degradation of the title compound. The existence of vibrational modes correspond to the organic and inorganic groups are identified by the infrared and Raman spectroscopy in the frequency ranges 500-4000 and 25-4000 cm-1, respectively.

  19. The specific surface area of methane hydrate formed in different conditions and manners

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The specific surface area of methane hydrates, formed both in the presence and absence of sodium dodecyl sulfate (SDS) and processed in different manners (stirring, compacting, holding the hydrates at the formation conditions for different periods of time, cooling the hydrates for different periods of time before depressurizing them), was measured under atmospheric pressure and temperatures below ice point. It was found that the specific surface area of hydrate increased with the decreasing temperature. The methane hydrate in the presence of SDS was shown to be of bigger specific surface areas than pure methane hydrates. The experimental results further demonstrated that the manners of forming and processing hydrates affected the specific surface area of hydrate samples. Stirring or compacting made the hydrate become finer and led to a bigger specific surface area.

  20. Exact solutions of equation of transverse vibrations for a bar with a specific cross section variation law

    Science.gov (United States)

    Mironov, M. A.

    2017-01-01

    Flexural wave propagation along a bar whose thickness smoothly decreases down to zero within its end piece is considered. The propagation velocity tends to zero as the tapered end of the bar is approached, and the time of wave propagation to the tapered end is infinite. As a consequence, waves propagating along the bar are not reflected from the end. Previous quantitative study of the effect in the WKB approximation shows that, in the case of parabolic tapering, the WKB approximation yields a uniform asymptotics, which is valid (or invalid) for any of the bar's cross sections. In the case of a bar with parabolic tapering, the equation of flexural vibrations of the bar has exact analytic solutions in the form of power functions. Based on these solutions, a modified WKB approximation is proposed to solve equations for bars with nonparabolic thickness variation laws. The input impedance of a bar with a parabolic tapering is calculated and analyzed.

  1. Probing the structure and nano-scale mechanical properties of polymer surfaces with scanning force microscopy and sum frequency vibrational spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Gracias, David Hugo [Univ. of California, Berkeley, CA (United States)

    1999-05-01

    Scanning Force Microscopy (SFM) has been used to quantitatively measure the elastic modulus, friction and hardness of polymer surfaces with special emphasis on polyethylene and polypropylene. In the experiments, tips of different radii of curvature ranging from 20 nm to 1000 nm have been used and the high pressure applied by the SFM have been observed to affect the values obtained in the measurements. The contact of the SFM tip with the polymer surface is explained by fitting the experimental curves to theoretical predictions of contact mechanics. Sum Frequency Generation (SFG) Vibrational Spectroscopy has been used to measure vibrational spectra of polymer surfaces in the vibrational range of 2700 to 3100 cm-1. Strong correlations are established between surface chemistry and surface structure as probed by SFG and mechanical properties measured by SFM on the surfaces. In these studies segregation of low surface energy moieties, from the bulk of the polymer to the surface have been studied. It was found that surface segregation occurs in miscible polymer blends and a small concentration of surface active polymer can be used to totally modify the surface properties of the blend. A novel high vacuum SFM was built to do temperature dependent measurements of mechanical changes occurring at the surface of polypropylene during the glass transition of the polymer. Using this instrument the modulus and friction of polypropylene was measured in the range of room temperature to ˜-60°C. An increase in the ordering of the backbone of the polymer chains below the glass transition measured by SFG correlates well with the increase in modulus measured on the same surface with SFM. Friction measurements have been done on polyethylene with three different instruments by applying loads ranging from nN to sub newton i.e. over eight orders of magnitude. Pressure and contact area effects were observed to play a significant role in determining the frictional response of the polymer

  2. Surface stress effect on the vibration and instability of nanoscale pipes conveying fluid based on a size-dependent Timoshenko beam model

    Science.gov (United States)

    Ansari, R.; Gholami, R.; Norouzzadeh, A.; Darabi, M. A.

    2015-10-01

    Presented in this paper is a precise investigation of the effect of surface stress on the vibration characteristics and instability of fluid-conveying nanoscale pipes. To this end, the nanoscale pipe is modeled as a Timoshenko nanobeam. The equations of motion of the nanoscale pipe are obtained based on Hamilton's principle and the Gurtin-Murdoch continuum elasticity incorporating the surface stress effect. Afterwards, the generalized differential quadrature method is employed to discretize the governing equations and associated boundary conditions. To what extent important parameters such as the thickness, material and surface stress modulus, residual surface stress, surface density, and boundary conditions influence the natural frequency of nanoscale pipes and the critical velocity of fluid is discussed.

  3. Research on the Influence of Cutting Condition on the Surface Microstruct ure of Ultra-thin Wall Parts in Ultrasonic Vibration Cutting

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    In many fields of high-tech industry the ultra-t hi n wall parts are employed. In this paper the experiments were carried out to dis cuss the surface microstructure of the camera's guided drawtube by applying ult rasonic vibration cutting device to the traditional lathe. The influence rule of the cutting condition on the surface roughness was put forward, which was drawn by comparing the ultrasonic cutting with the common cutting by use of the cemen ted carbide tool and the polycrystalline diamond (PCD) t...

  4. Raman and surface enhanced Raman spectroscopic studies of specific, small molecule activator of histone acetyltransferase p300

    Science.gov (United States)

    Kundu, Partha P.; Pavan Kumar, G. V.; Mantelingu, Kempegowda; Kundu, Tapas K.; Narayana, Chandrabhas

    2011-07-01

    We report for the first time, the Raman and surface enhanced Raman scattering (SERS) studies of N-(4-chloro-3-trifluoromethyl-phenyl)-2-ethoxy-benzamide (CTB). This molecule is specific activator of human histone acetyltransferase (HAT), p300, and serves as lead molecule to design anti-neoplastic therapeutics. A detailed Raman and SERS band assignments have been performed for CTB, which are compared with the density functional theory calculations. The observed red shift of N sbnd H stretching frequency from the computed wavenumber indicates the weakening of N sbnd H bond resulting from proton transfer to the neighboring oxygen atom. We observe Ag sbnd N vibrational mode at 234 cm -1 in SERS of CTB. This indicates there is a metal-molecule bond leading to chemical enhancement in SERS. We also observe, enhancement in the modes pertaining to substituted benzene rings and methyl groups. Based on SERS analysis we propose the adsorption sites and the orientation of CTB on silver surface.

  5. Effects of closed chain exercises for the lumbar region performed with local vibration applied to an unstable support surface on the thickness and length of the transverse abdominis.

    Science.gov (United States)

    Yun, Kihyun; Lee, Sangyong; Park, Jinsik

    2015-01-01

    [Purpose] This study examined the effects of closed chain exercises performed with local vibration applied to an unstable support surface on the thickness and length of the transverse abdominis. [Subjects] The subjects were 64 healthy university students who were randomly assigned to a bridge exercise with sling and vibration group (BESVG, n=30) and a bridge exercise with sling group (BESG, n=34). [Methods] The bridge exercise was repeated four times per set and a total of 18 sets were performed: 9 sets in a supine position and 9 sets in a prone position. In both the BESVG and the BESG groups, the thickness and length of the transverse abdominis (TrA) were measured using ultrasonography with the abdomen "drawn-in" and the pressure of a biofeedback unit maintained at 40 mmHg, both before and after the intervention. [Results] In intra-group comparisons, the BESVG showed significant increases in the thickness of the TrA and significant decreases in the length of the TrA. The BESG showed significant increases in the thickness of the TrA. The BESVG showed significant increases in the thickness of the TrA and significant decreases in the length of the TrA compared to BESG. [Conclusion] Closed chain exercises for the lumbar region performed with local vibration applied to slings, which are unstable support surfaces, are an effective intervention for altering the thickness and length of the TrA.

  6. Power spectral density function and spatial autocorrelation of the ambient vibration full-wavefield generated by a distribution of spatially correlated surface sources

    Science.gov (United States)

    Lunedei, Enrico; Albarello, Dario

    2016-03-01

    Synthetic dispersion curves are here computed in the frame of an ambient-vibration full-wavefield model, which relies on the description of both ambient-vibration ground displacement and its sources as stochastic fields defined on the Earth's surface, stationary in time and homogeneous in space. In this model, previously developed for computing synthetic Horizontal-to-Vertical Spectral Ratio curves, the power spectral density function and the spatial autocorrelation of the displacement are naturally described as functions of the power spectral density function of the generating forces and of the subsoil properties (via the relevant Green's function), by also accounting for spatial correlation of these forces. Dispersion curves are computed from the displacement power spectral density function and from the spatial autocorrelation according with the well-known f-k and SPAC techniques, respectively. Two examples illustrate the way this new ambient-vibration model works, showing its possible use in better understanding the role of the surface waves in forming the dispersion curves, as well as its capability to capture some remarkable experimental findings.

  7. Diffraction Studies of the Atomic Vibrations of Bulk and Surface Atoms in the Reciprocal and Real Spaces of Nanocrystalline SiC

    Science.gov (United States)

    Stelmakh, S.; Grzanka, E.; Weber, H.-P.; Vogel, S.; Palosz, B.; Palosz, B.

    2004-01-01

    To describe and evaluate the vibrational properties of nanoparticles it is necessary to distinguish between the surface and the core of the particles. Theoretical calculations show that vibrational density of states of the inner atoms of nanograins is similar to bulk material but shifted to higher energies which can be explained by the fact that the gain core is stressed (hardened) due to the presence of internal pressure. Theoretical calculations also show that there is a difference between vibrational properties of a crystal lattice of the grain interior in isolated particles and in a dense (sintered) nanocrystalline material. This is probably due to a coupling of the modes inside the grains via the grain boundaries in dense nanocrystalline bodies. We examined strains present in the surface shell based on examination of diamond and Sic nanocrystals in reciprocal (Bragg-type scattering) and real (PDF analysis) space analysis of neutron diffraction data. Recently we examined the atomic thermal motions in nanocrystalline Sic based on the assumption of a simple Einstein model for uncorrelated atomic notions. According to this model, the Bragg intensity is attenuated as a function of scattering angle by the Debye-Waller factor. Based on this assumption overall temperature factors were determined from the Wilson plots.

  8. MCSCF/CI ground state potential energy surface, dipole moment function, and gas phase vibrational frequencies for the nitrogen dioxide positive ion

    Energy Technology Data Exchange (ETDEWEB)

    Hopper, D.G.

    1980-05-01

    The ground state potential energy surface for the nitrogen dioxide positive ion, NO/sup +//sub 2/X /sup 1/..sigma../sup +//sub g/(..sigma../sup +/,A/sub 1/,A'), has been scanned with a correlated wave function to obtain directly, for the first time, the gas phase equilibrium geometry, force constants, vibrational frequencies, and dipole moment function. The wave function for this scan was constructed from a double-zeta plus polarization one-electron basis with a 12 configuration MCSCF determination of the orbital basis for a full valence /sup 1/..sigma../sup +//sub g/ configuration interaction expansion. The calculated equilibrium bond length is 1.12 A. The vibrational frequencies are computed to be ..nu../sub 1/=1514, ..nu../sub 2/=679, and ..nu../sub 3/=2614 cm/sup -1/ The present ab initio results differ significantly from crystalline spectroscopic studies and are, thus, the best values available for the gas phase vibrational frequencies. The dipole moment function is nonzero at the ..sigma../sup +/, A/sub 1/, and A' geometries included in the potential surface scan, and is obtained here to provide for the future a priori calculation of the infrared band intensities.

  9. Theoretical studies for the N{sub 2}–N{sub 2}O van der Waals complex: The potential energy surface, intermolecular vibrations, and rotational transition frequencies

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Rui [Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Centre for Magnetic Resonance, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071 (China); School of Mathematics and Information Science, North China University of Water Resources and Electric Power, Zhengzhou 450011 (China); Zheng, Limin; Yang, Minghui, E-mail: yplu@ntu.edu.sg, E-mail: yangmh@wipm.ac.cn [Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Centre for Magnetic Resonance, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071 (China); Lu, Yunpeng, E-mail: yplu@ntu.edu.sg, E-mail: yangmh@wipm.ac.cn [Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371 (Singapore)

    2015-10-21

    Theoretical studies of the potential energy surface (PES) and bound states are performed for the N{sub 2}–N{sub 2}O van der Waals (vdW) complex. A four-dimensional intermolecular PES is constructed at the level of single and double excitation coupled-cluster method with a non-iterative perturbation treatment of triple excitations [CCSD(T)] with aug-cc-pVTZ basis set supplemented with bond functions. Two equivalent T-shaped global minima are located, in which the O atom of N{sub 2}O monomer is near the N{sub 2} monomer. The intermolecular fundamental vibrational states are assigned by inspecting the orientation of the nodal surface of the wavefunctions. The calculated frequency for intermolecular disrotation mode is 23.086 cm{sup −1}, which is in good agreement with the available experimental data of 22.334 cm{sup −1}. A negligible tunneling splitting with the value of 4.2 MHz is determined for the ground vibrational state and the tunneling splitting increases as the increment of the vibrational frequencies. Rotational levels and transition frequencies are calculated for both isotopomers {sup 14}N{sub 2}–N{sub 2}O and {sup 15}N{sub 2}–N{sub 2}O. The accuracy of the PES is validated by the good agreement between theoretical and experimental results for the transition frequencies and spectroscopic parameters.

  10. Studying the influence of surface effects on vibration behavior of size-dependent cracked FG Timoshenko nanobeam considering nonlocal elasticity and elastic foundation

    Science.gov (United States)

    Ghadiri, Majid; Soltanpour, Mahdi; Yazdi, Ali; Safi, Mohsen

    2016-05-01

    Free transverse vibration of a size-dependent cracked functionally graded (FG) Timoshenko nanobeam resting on a polymer elastic foundation is investigated in the present study. Also, all of the surface effects: surface density, surface elasticity and residual surface tension are studied. Moreover, satisfying the balance condition between the nanobeam and its surfaces was discussed. According to the power-law distribution, it is supposed that the material properties of the FG nanobeam are varying continuously across the thickness. Considering the small-scale effect, the Eringen's nonlocal theory is used; accounting the effect of polymer elastic foundation, the Winkler model is proposed. For this purpose, the equations of motion of the FG Timoshenko nanobeam and boundary conditions are obtained using Hamilton's principle. To find the analytical solutions for equations of motion of the FG nanobeam, the separation of variables method is employed. Two cases of boundary conditions, i.e., simply supported-simply supported (SS) and clamped-clamped (CC) are investigated in the present work. Numerical results are demonstrating a good agreement between the results of the present study and some available cases in the literature. The emphasis of the present study is on investigating the effect of various parameters such as crack severity, crack position, gradient index, mode number, nonlocal parameter, elastic foundation parameter and nanobeam length. It is clearly revealed that the vibrational behavior of a FG nanobeam is depending significantly on these effects. Also, these numerical results can be serving as benchmarks for future studies of FG nanobeams.

  11. Preparation and Characterization of Porous Yttrium Oxide Powders with High Specific Surface Area

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The porous cubic yttrium oxides with high specific surface area were prepared by the explosive decomposition of yttrium nitrate and its complex formed with methyl salicylate. The specific surface area and properties of powders synthesized at various temperatures were characterized using BET, X-ray diffraction (XRD), infrared spectra (IR), and scanning electron microscopy (SEM). The results indicate that the highest specific surface area is found to be 65.37 m2*g-1 at the calcination temperature of 600 ℃, and then decreases to 20.33 m2*g-1 with the calcination temperature rising from 600 to 900 ℃. The powders show strong surface activity for adsorping water and carbon dioxide in air, which also decreases with the rising calcination temperature. The drop both on the surface area and surface activity of samples at higher temperatures may be due to pore-narrowing(sintering) effects.

  12. Inelastic surface vibrations versus energy-dependent nucleus–nucleus potential in sub-barrier fusion dynamics of $^{6}_{3}$ Li + $^{144} -{62}$Sm system

    Indian Academy of Sciences (India)

    GAUTAM MANJEET SINGH

    2016-05-01

    Limitations of the static Woods–Saxon potential and the applicability of the energy dependent Woods–Saxon potential (EDWSP) model within the framework of one-dimensional Wong formula to explore the sub-barrier fusion data are highlighted. The inelastic surface excitations of the fusing nuclei are found to be dominating in the enhancement of sub-barrier fusion excitation function data and the effects of such dominant vibrational states are exploited through the coupled channel calculations obtained by using the code CCFULL. It is worth mentioning here that the influence of multiphonon vibrational states of the reactants can be simulated by introducing the energy dependence in the nucleus–nucleus potential.

  13. Application of a time-dependent Hartree approach on several surfaces to the vibrational predissociation of Ne2I2

    Science.gov (United States)

    Carmona-Novillo, E.; Campos-Martínez, J.; Hernández, M. I.; Roncero, O.; Villarreal, P.; Delgado Barrio, G.

    In this work we explore the application of a time-dependent Hartree (TDH) scheme to study the vibrational predissociation of Ne2I2 van der Waals clusters. The present approach is based on equations of motion extracted from the usual variational principle where the Hamiltonian has been previously represented in a set of diatomic vibrational states. The procedure leads to a set of coupled equations for the different modes on each diabatic state with, however, explicit separation between those modes. The application on a problem that inherently requires long-time propagation is shown to be successful. Calculated lifetimes compare well with previous calculations as well as with available experimental data. A more detailed mechanism, as the breath of the angular mode on the different vibrational channels, is better described.

  14. Properties that influence the specific surface areas of carbon nanotubes and nanofibers.

    Science.gov (United States)

    Birch, M Eileen; Ruda-Eberenz, Toni A; Chai, Ming; Andrews, Ronnee; Hatfield, Randal L

    2013-11-01

    Commercially available carbon nanotubes and nanofibers were analyzed to examine possible relationships between their Brunauer-Emmett-Teller specific surface areas (SSAs) and their physical and chemical properties. Properties found to influence surface area were number of walls/diameter, impurities, and surface functionalization with hydroxyl and carboxyl groups. Characterization by electron microscopy, energy-dispersive X-ray spectrometry, thermogravimetric analysis, and elemental analysis indicates that SSA can provide insight on carbon nanomaterials properties, which can differ vastly depending on synthesis parameters and post-production treatments. In this study, how different properties may influence surface area is discussed. The materials examined have a wide range of surface areas. The measured surface areas differed from product specifications, to varying degrees, and between similar products. Findings emphasize the multiple factors that influence surface area and mark its utility in carbon nanomaterial characterization, a prerequisite to understanding their potential applications and toxicities. Implications for occupational monitoring are discussed.

  15. Role of specific amine surface configurations for grafted surfaces: implications for nanostructured CO2 adsorbents.

    Science.gov (United States)

    Shimizu, Steven; Song, Changsik; Strano, Michael

    2011-03-15

    Amine-grafted porous materials that capture CO2 from emission streams have been considered to be potential alternatives to the more energy-intensive liquid amine systems currently employed. An underappreciated fact in the uptake mechanism of these materials is that under dry, anhydrous conditions each CO2 molecule must react with two adjacent amine groups to adsorb onto the surface, which makes the configuration of amine groups on the surface critically important. Using this chemical mechanism, we developed a semiempirical adsorption isotherm equation that allows straightforward computation of the adsorption isotherm from an arbitrary surface configuration of grafted amines for honeycomb, square, and triangular lattices. The model makes use of the fact that the distribution of amines with respect to the number of nearest neighbors, referred to as the z-histogram, along with the amine loading and equilibrium constant, uniquely determine the adsorption characteristics to a very good approximation. This model was used to predict the range of uptakes possible just through surface configuration, and it was used to fit experimental data in the literature to give a meaningful equilibrium constant and show how efficiently amines were utilized. We also demonstrate how the model can be utilized to design more efficient nanostructured adsorbents and polymer-based adsorbents. Recommendations for exploiting the role of surface configuration include the use of linear instead of branched polyamines, higher amine grafting densities, the use of flexible, less bulky, long, and rotationally free amine groups, and increased silanol densities.

  16. Sum frequency generation vibrational spectroscopy (SFG-VS) for complex molecular surfaces and interfaces: Spectral lineshape measurement and analysis plus some controversial issues

    Science.gov (United States)

    Wang, Hong-Fei

    2016-12-01

    Sum-frequency generation vibrational spectroscopy (SFG-VS) was first developed in the 1980s and it has been proven a uniquely sensitive and surface/interface selective spectroscopic probe for characterization of the structure, conformation and dynamics of molecular surfaces and interfaces. In recent years, there have been many progresses in the development of methodology and instrumentation in the SFG-VS toolbox that have significantly broadened the application to complex molecular surfaces and interfaces. In this review, after presenting a unified view on the theory and methodology focusing on the SFG-VS spectral lineshape, as well as the new opportunities in SFG-VS applications with such developments, some of the controversial issues that have been puzzling the community are discussed. The aim of this review is to present to the researchers and students interested in molecular surfaces and interfacial sciences up-to-date perspectives complementary to the existing textbooks and reviews on SFG-VS.

  17. Back-surface gold mirrors for vibrationally resonant sum-frequency (VR-SFG) spectroscopy using 3-mercaptopropyltrimethoxysilane as an adhesion promoter.

    Science.gov (United States)

    Quast, Arthur D; Zhang, Feng; Linford, Matthew R; Patterson, James E

    2011-06-01

    Back-surface mirrors are needed as reference materials for vibrationally resonant sum-frequency generation (VR-SFG) probing of liquid-solid interfaces. Conventional noble metal mirrors are not suitable for back-surface applications due to the presence of a metal adhesion layer (chromium or titanium) between the window substrate and the reflective metal surface. Using vapor deposited 3-mercaptopropyltrimethoxysilane (MPTMS) as a bi-functional adhesion promoter, gold mirrors were fabricated on fused silica substrates. These mirrors exhibit excellent gold adhesion as determined by the Scotch(®) tape test. They also produce minimal spectroscopic interference in the C-H stretching region (2800-3000 cm(-1)), as characterized by VR-SFG. These mirrors are thus robust and can be used as back-surface mirrors for a variety of applications, including reference mirrors for VR-SFG.

  18. Sum frequency generation vibrational spectroscopy (SFG-VS) for complex molecular surfaces and interfaces: Spectral lineshape measurement and analysis plus some controversial issues

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hong-Fei

    2016-12-01

    Sum-frequency generation vibrational spectroscopy (SFG-VS) was first developed in the 1980s and it has been proven a uniquely sensitive and surface/interface selective spectroscopic probe for characterization of the structure, conformation and dynamics of molecular surfaces and interfaces. In recent years, there has been significant progress in the development of methodology and instrumentation in the SFG-VS toolbox that has significantly broadened the application to complex molecular surfaces and interfaces. In this review, after presenting a unified view on the theory and methodology focusing on the SFG-VS spectral lineshape, as well as the new opportunities in SFG-VS applications with such developments, some of the controversial issues that have been puzzling the community are to be discussed. The aim of this review is to present to the researchers and students interested in molecular surfaces and interfacial sciences up-to-date perspectives complementary to the existing textbooks and reviews on SFG-VS.

  19. A quantitative method to discriminate between non-specific and specific lectin-glycan interactions on silicon-modified surfaces.

    Science.gov (United States)

    Yang, Jie; Siriwardena, Aloysius; Boukherroub, Rabah; Ozanam, François; Szunerits, Sabine; Gouget-Laemmel, Anne Chantal

    2016-02-15

    Essential to the success of any surface-based carbohydrate biochip technology is that interactions of the particular interface with the target protein be reliable and reproducible and not susceptible to unwanted nonspecific adsorption events. This condition is particularly important when the technology is intended for the evaluation of low-affinity interactions such as those typically encountered between lectins and their monomeric glycan ligands. In this paper, we describe the fabrication of glycan (mannoside and lactoside) monolayers immobilized on hydrogenated crystalline silicon (111) surfaces. An efficient conjugation protocol featuring a key "click"-based coupling step has been developed which ensures the obtention of interfaces with controlled glycan density. The adsorption behavior of these newly developed interfaces with the lectins, Lens culinaris and Peanut agglutinin, has been probed using quantitative IR-ATR and the data interpreted using various isothermal models. The analysis reveals that protein physisorption to the interface is more prevalent than specific chemisorption for the majority of washing protocols investigated. Physisorption can be greatly suppressed through application of a strong surfactinated rinse. The coexistence of chemisorption and physisorption processes is further demonstrated by quantification of the amounts of adsorbed proteins distributed on the surface, in correlation with the results obtained by atomic force microscopy (AFM). Taken together, the data demonstrates that the nonspecific adsorption of proteins to these glycan-terminated surfaces can be effectively eliminated through the proper control of the chemical structure of the surface monolayer combined with the implementation of an appropriate surface-rinse protocol.

  20. Catalyzed hydrogenation of nitrogen and ethylene on metal (Fe, Pt) single crystal surfaces and effects of coadsorption: A sum frequency generation vibrational spectroscopy study

    Energy Technology Data Exchange (ETDEWEB)

    Westerberg, Staffan Per Gustav [Univ. of California, Berkeley, CA (United States)

    2004-01-01

    High-pressure catalytic reactions and associated processes, such as adsorption have been studied on a molecular level on single crystal surfaces. Sum Frequency Generation (SFG) vibrational spectroscopy together with Auger Electron Spectroscopy (AES), Temperature Programmed Desorption (TPD) and Gas Chromatography (GC) were used to investigate the nature of species on catalytic surfaces and to measure the catalytic reaction rates. Special attention has been directed at studying high-pressure reactions and in particular, ammonia synthesis in order to identify reaction intermediates and the influence of adsorbates on the surface during reaction conditions. The adsorption of gases N2, H2, O2 and NH3 that play a role in ammonia synthesis have been studied on the Fe(111) crystal surface by sum frequency generation vibrational spectroscopy using an integrated Ultra-High Vacuum (UHV)/high-pressure system. SFG spectra are presented for the dissociation intermediates, NH2 (~3325 cm-1) and NH (~3235 cm-1) under high pressure of ammonia (200 Torr) on the clean Fe(111) surface. Addition of 0.5 Torr of oxygen to 200 Torr of ammonia does not significantly change the bonding of dissociation intermediates to the surface. However, it leads to a phase change of nearly 180° between the resonant and non-resonant second order non-linear susceptibility of the surface, demonstrated by the reversal of the SFG spectral features. Heating the surface in the presence of 200 Torr ammonia and 0.5 Torr oxygen reduces the oxygen coverage, which can be seen from the SFG spectra as another relative phase change of 180°. The reduction of the oxide is also supported by Auger electron spectroscopy. The result suggests that the phase change of the spectral features could serve as a sensitive indicator of the chemical environment of the adsorbates.

  1. Catalyzed hydrogenation of nitrogen and ethylene on metal (Fe, Pt) single crystal surfaces and effects of coadsorption: A sum frequency generation vibrational spectroscopy study

    Energy Technology Data Exchange (ETDEWEB)

    Westerberg, Staffan Per Gustav

    2004-12-15

    High-pressure catalytic reactions and associated processes, such as adsorption have been studied on a molecular level on single crystal surfaces. Sum Frequency Generation (SFG) vibrational spectroscopy together with Auger Electron Spectroscopy (AES), Temperature Programmed Desorption (TPD) and Gas Chromatography (GC) were used to investigate the nature of species on catalytic surfaces and to measure the catalytic reaction rates. Special attention has been directed at studying high-pressure reactions and in particular, ammonia synthesis in order to identify reaction intermediates and the influence of adsorbates on the surface during reaction conditions. The adsorption of gases N{sub 2}, H{sub 2}, O{sub 2} and NH{sub 3} that play a role in ammonia synthesis have been studied on the Fe(111) crystal surface by sum frequency generation vibrational spectroscopy using an integrated Ultra-High Vacuum (UHV)/high-pressure system. SFG spectra are presented for the dissociation intermediates, NH{sub 2} ({approx}3325 cm{sup -1}) and NH ({approx}3235 cm{sup -1}) under high pressure of ammonia (200 Torr) on the clean Fe(111) surface. Addition of 0.5 Torr of oxygen to 200 Torr of ammonia does not significantly change the bonding of dissociation intermediates to the surface. However, it leads to a phase change of nearly 180{sup o} between the resonant and non-resonant second order non-linear susceptibility of the surface, demonstrated by the reversal of the SFG spectral features. Heating the surface in the presence of 200 Torr ammonia and 0.5 Torr oxygen reduces the oxygen coverage, which can be seen from the SFG spectra as another relative phase change of 180{sup o}. The reduction of the oxide is also supported by Auger electron spectroscopy. The result suggests that the phase change of the spectral features could serve as a sensitive indicator of the chemical environment of the adsorbates.

  2. Surface functionalization of SPR chip for specific molecular interaction analysis under flow condition

    Directory of Open Access Journals (Sweden)

    Tao Ma

    2017-03-01

    Full Text Available Surface functionalization of sensor chip for probe immobilization is crucial for the biosensing applications of surface plasmon resonance (SPR sensors. In this paper, we report a method circulating the dopamine aqueous solution to coat polydopamine film on sensing surface for surface functionalization of SPR chip. The polydopamine film with available thickness can be easily prepared by controlling the circulation time and the biorecognition elements can be immobilized on the polydopamine film for specific molecular interaction analysis. These operations are all performed under flow condition in the fluidic system, and have the advantages of easy implementation, less time consuming, and low cost, because the reagents and devices used in the operations are routinely applied in most laboratories. In this study, the specific absorption between the protein A probe immobilized on the sensing surface and human immunoglobulin G in the buffer is monitored based on this surface functionalization strategy to demonstrated its feasibility for SPR biosensing applications.

  3. Electronic and Vibrational Properties of meso -Tetraphenylporphyrin on Silver Substrates

    Energy Technology Data Exchange (ETDEWEB)

    El-Khoury, Patrick Z.; Honkala, Karoliina; Hess, Wayne P.

    2014-09-18

    The electronic and vibrational properties of meso-tetraphenylporphyrin (mtpp) on silver substrates are investigated using UV–vis and surface-enhanced resonance Raman scattering (SERRS) spectroscopy. Whereas the vibrational signatures associated with the tetrapyrrole backbone exhibit minor variations throughout sequences of consecutively recorded SERRS spectra, the C=C stretching vibrational modes localized on the meso-phenyl moieties of mtpp exhibit noticeable intensity fluctuations, masked in the average SERRS response. Finally, we attribute the observed vibrational-state-specific blinking events to conformational changes in mtpp, namely, torsional flexibility which mediates the coupling between the π-framework of the meso-phenyls and the underlying metal substrate.

  4. Identification and control of downhole vibration based on surface data%基于地表数据的井下振动识别与控制

    Institute of Scientific and Technical Information of China (English)

    韩加庚; 汪海阁; 林玥翔; 崔猛

    2016-01-01

    钻柱振动识别与控制对于减少钻井过程中事故复杂、防止钻头提前失效具有重要意义。全球每年与钻柱振动相关的失效和破坏的经济损失高达3亿美元。若能实时监测钻头破岩状态,有效识别并控制钻柱有害振动,则能大大降低这种损失。调研了国内外对钻井振动问题的研究和应用情况,讨论了钻具振动的产生机理及其地表数据响应关系。在基于比能优化技术基础上,建立了一套根据地表数据实时识别并控制井下振动的方法。现场应用表明,振动识别与控制技术能够准确判断井下振动,通过不断优化钻井参数可以消除井下瓶颈因素,挖掘提速潜力,有望为钻井提速和降低成本探寻一条新途径。%Identification and control of vibrations of drill strings are of great importance to eliminate drilling accidents and protect drilling bits from premature failure. Globally, economic losses related to failure and damages induced by drill string vibration are up to $300 million every year. Such losses can be reduced significantly as long as rock-breading conditions can be monitored in real time and hazardous vibration of drill strings can be identified and controlled effectively. In this paper, existing researches and applications related to drilling vibration both at home and abroad were reviewed, and mechanisms for generation of such drill-tool vibrations and their relationship with surface data were discussed. Based in energy density optimization, a package of techniques for identification and control of downhole vibration on the baisis of surface data were developed. Field application results show that the vibration identification and control techniques can accurately detect downhole vibration. Through continuous optimization of drilling parameters, the techniques can help to eliminate downhole bottleneck factors so as to fully explore the potential of improving drilling speed. These

  5. Structure of butanol and hexanol at aqueous, ammonium bisulfate, and sulfuric acid solution surfaces investigated by vibrational sum frequency generation spectroscopy.

    Science.gov (United States)

    Van Loon, Lisa L; Minor, Rena N; Allen, Heather C

    2007-08-09

    The organization of 1-butanol and 1-hexanol at the air-liquid interface of aqueous, aqueous ammonium bisulfate, and sulfuric acid solutions was investigated using vibrational broad bandwidth sum frequency generation spectroscopy. There is spectroscopic evidence supporting the formation of centrosymmetric structures at the surface of pure butanol and pure hexanol. At aqueous, ammonium bisulfate, and at most sulfuric acid solution surfaces, butanol molecules organize in all-trans conformations. This suggests that butanol self-aggregates. The spectrum for the 0.052 M butanol in 59.5 wt % sulfuric acid solution is different from the other butanol solution spectra, that is, the surface butanol molecules are observed to possess a significant number of gauche defects. Relative to surface butanol, surface hexanol chains are more disordered at the surface of their respective solutions. Statistically, an increase in the number of gauche defects is expected for hexanol relative to butanol, a six carbon chain vs a four carbon chain. Yet, self-aggregation of hexanol at its aqueous solution surfaces is not ruled out because the methylene spectral contribution is relatively small. The surface spectra for butanol and hexanol also show evidence for salting out from the ammonium bisulfate solutions.

  6. Synthesis and characterization of large specific surface area nanostructured amorphous silica materials.

    Science.gov (United States)

    Marquez-Linares, Francisco; Roque-Malherbe, Rolando M A

    2006-04-01

    Large specific surface area materials attract wide attention because of their applications in adsorption, catalysis, and nanotechnology. In the present study, we describe the synthesis and characterization of nanostructured amorphous silica materials. These materials were obtained by means of a modification of the Stobe-Fink-Bohn (SFB) method. The morphology and essential features of the synthesized materials have been studied using an automated surface area and pore size analyzer and scanning electron microscopy. The existence of a micro/mesoporous structure in the obtained materials has been established. It was also found that the obtained particle packing materials show large specific surface area up to 1,600 m2/g. (To our best knowledge, there is no any reported amorphous silica material with such a higher specific surface area.) The obtained materials could be useful in the manufacture of adsorbents, catalyst supports, and other nanotechnological applications.

  7. A plasticity principle of convex quadrilaterals on a complete convex surface of bounded specific curvature

    CERN Document Server

    Zachos, Anastasios

    2010-01-01

    We obtain the plasticity equations for convex quadrilaterals on a complete convex surface with bounded specific curvature and derive a plasticity principle which states that: Given four shortest arcs which meet at the weighted Fermat-Torricelli point P_F and their endpoints form a convex quadrilateral, an increase of the weight that corresponds to a shortest arc causes a decrease to the two weights that correspond to the two neighboring shortest arcs and an increase to the weight that corresponds to the opposite shortest arc. We show a connection between the plasticity of convex quadrilaterals on a complete convex surface with bounded specific curvature with the plasticity of generalized convex quadrilaterals on a manifold which is composed by triangles located on a complete convex surface of bounded specific curvature and triangles located on a two dimensional sphere whose constant Gaussian curvature equals to the infimum or supremum of the specific curvature. Furthermore, we give some cases of geometrizatio...

  8. Surface tension and specific heat of liquid Ni70.2Si29.8 alloy

    Institute of Scientific and Technical Information of China (English)

    WANG Haipeng; WEI Bingbo

    2005-01-01

    The surface tension and specific heat of stable and metastable liquid Ni70.2Si29.8 eutectic alloy were measured by electromagnetic levitation oscillating drop method and drop calorimetry. The surface tension depends on temperature linearly within the experimental undercooling regime of 0-182 K (0.12 TE). Its value is 1.693 N·m-1 at the eutectic temperature of 1488 K, and the temperature coefficient is -4.23×10-4 N·m-1·K-1. For the specific heat measurement, the maximum undercooling is up to 253 K (0.17 TE). The specific heat is determined as a polynomial function of temperature in the experimental temperature regime. On the basis of the measured data of surface tension and specific heat, the temperature-dependent density, excess volume and sound speed of liquid Ni70.2Si29.8 alloy are predicted theoretically.

  9. Simultaneous investigation of blast induced ground vibration and airblast effects on safety level of structures and human in surface blasting

    Institute of Scientific and Technical Information of China (English)

    Faramarzi Farhad⇑; Ebrahimi Farsangi Mohammad Ali; Mansouri Hamid

    2014-01-01

    The significance of studying, monitoring and predicting blast induced vibration and noise level in mining and civil activities is justified in the capability of imposing damages, sense of uncertainty due to negative psychological impacts on involved personnel and also judicial complaints of local inhabitants in the nearby area. This paper presents achieved results during an investigation carried out at Sungun Copper Mine, Iran. Besides, the research also studied the significance of blast induced ground vibration and air-blast on safety aspects of nearby structures, potential risks, frequency analysis, and human response. According to the United States Bureau of Mines (USBM) standard, the attenuation equations were devel-oped using field records. A general frequency analysis and risk evaluation revealed that:94%of generated frequencies are less than 14 Hz which is within the natural frequency of structures that increases risk of damage. At the end, studies of human response showed destructive effects of the phenomena by ranging between 2.54 and 25.40 mm/s for ground vibrations and by the average value of 110 dB for noise levels which could increase sense of uncertainty among involved employees.

  10. Calculation of the structure, potential energy surface, vibrational dynamics, and electric dipole properties for the Xe:HI van der Waals complex.

    Science.gov (United States)

    Preller, M; Grunenberg, J; Bulychev, V P; Bulanin, M O

    2011-05-07

    We report the structure and spectroscopic characteristics for the Xe:HI van der Waals binary isomers determined from variational solutions of two-dimensional and three-dimensional (3D) vibrational Schrödinger equations. The solutions are based on a potential energy surface computed at the coupled-cluster level of theory including single and double excitations and a non-iterative perturbation treatment of triple excitations [CCSD(T)]. The dipole moment surface was calculated using quadratic configuration interaction (QCISD). The global potential minimum is shown to be located at the anti-hydrogen-bonded Xe-IH isomer, 21 cm(-1) below the secondary local minimum associated with the hydrogen-bonded Xe-HI isomeric form. The dissociation energy from the global minimum is 245.9 cm(-1). 3D Schrödinger equations are solved for the rotational quantum numbers J = k = 0, 1, and 2, without invoking an adiabatic separation of high- and low-frequency degrees of freedom. The vibrational ground state resides in the Xe-HI potential well, while the first excited state, 8.59 cm(-1) above the ground, occupies the Xe-IH well. We find that intra-complex dynamics exhibits a sudden transformation upon increase of the r(HI) bond length, accompanied by abrupt changes in the geometric and dipole parameters. A similar chaotic behavior is predicted to occur for Xe:DI at a shorter r(DI) bond length, which implies stronger coupling between low- and high-frequency motions in the heavier complex. Our calculations confirm a strong enhancement for the r(HI) stretch fundamental and a significant weakening for the first overtone vibrational transitions in Xe:HI, as compared to those in the free HI molecule. A qualitative explanation of this, earlier experimentally detected effect is suggested.

  11. Bacterial surface antigen-specific monoclonal antibodies used to detect beer spoilage pediococci.

    Science.gov (United States)

    Whiting, M S; Ingledew, W M; Lee, S Y; Ziola, B

    1999-08-01

    Fourteen monoclonal antibodies (Mabs) were isolated that react with surface antigens of Pediococcus beer spoilage organisms, including P. damnosus, P. pentosaceous, P. acidilactici, and unspeciated isolates. Immunoblotting, enzyme immunoassays (EIAs) of protease- and neuraminidase-treated surface antigen extracts, carbohydrate competition EIAs, and cardiolipin EIAs were used to characterize the bacterial antigens involved in Mab binding. Antigen stability in situ was tested by protease treatment or surface antigen extraction of washed bacteria. In most cases, the Mabs bind to Pediococcus surface antigens that appear to be covalently bound cell wall polymers resistant to alteration or removal from the bacterial surface. These bacterial surface antigen reactive Mabs show good potential for rapid, sensitive, and specific immunoassay detection of Pediococcus beer spoilage organisms.

  12. Site-specific immobilization of protein layers on gold surfaces via orthogonal sortases.

    Science.gov (United States)

    Raeeszadeh-Sarmazdeh, Maryam; Parthasarathy, Ranganath; Boder, Eric T

    2015-04-01

    We report a site-specific, sortase-mediated ligation to immobilize proteins layer-by-layer on a gold surface. Recombinant fluorescent proteins with a Sortase A recognition tag at the C-terminus were immobilized on peptide-modified gold surfaces. We used two sortases with different substrate specificities (Streptococcus pyogenes Sortase A and Staphylococcus aureus Sortase A) to immobilize layers of GFP and mCherry site-specifically on the gold surface. Surfaces were characterized using fluorescence and atomic force microscopy after immobilizing each layer of protein. Fluorescent micrographs showed that both protein immobilization on the modified gold surface and protein oligomerization are sortase-dependent. AFM images showed that either homogenous protein monolayers or layers of protein oligomers can be generated using appropriately tagged substrate proteins. Using Sortase A variants with orthogonal peptide substrate specificities, site-specific immobilization of appropriately tagged GFP onto a layer of immobilized mCherry was achieved without disruption of the underlying protein layer.

  13. Gene targeting in melanoma therapy: exploiting of surface markers and specific promoters

    Directory of Open Access Journals (Sweden)

    Sverdlov E. D.

    2012-01-01

    Full Text Available One of the problems of gene therapy of melanoma is effective expression of therapeutic gene in tumor cells and their metastases but not in normal cells. In this review, we will consider a two-step approach to a highly specific gene therapy. At the first step, therapeutic genes are delivered specifically to tumor cells using cell surface markers of melanoma cells as targets. At the second step, a specific expression of the therapeutic genes in tumor cells is ensured. Surface markers of melanoma cells were analyzed as potential targets for therapeutic treatment. Criteria for choosing the most promising targets are proposed. The use of specific melanoma promoters allows to further increase the specificity of treatment via transcriptional control of therapeutic gene expression in melanoma cells.

  14. Vibration interaction in a multiple flywheel system

    Science.gov (United States)

    Firth, Jordan; Black, Jonathan

    2012-03-01

    This paper investigates vibration interaction in a multiple flywheel system. Flywheels can be used for kinetic energy storage in a satellite Integrated Power and Attitude Control System (IPACS). One hitherto unstudied problem with IPACS is vibration interaction between multiple unbalanced wheels. This paper uses a linear state-space dynamics model to study the impact of vibration interaction. Specifically, imbalance-induced vibration inputs in one flywheel rotor are used to cause a resonant whirling vibration in another rotor. Extra-synchronous resonant vibrations are shown to exist, but with damping modeled the effect is minimal. Vibration is most severe when both rotors are spinning in the same direction.

  15. Surface effects on vibration analysis of elastically restrained piezoelectric nanobeams subjected to magneto-thermo-electrical field embedded in elastic medium

    Science.gov (United States)

    Marzbanrad, Javad; Boreiry, Mahya; Shaghaghi, Gholam Reza

    2017-04-01

    In the present study, a generalized nonlocal beam theory is utilized to study the magneto-thermo-mechanical vibration characteristic of piezoelectric nanobeam by considering surface effects rested in elastic medium for various elastic boundary conditions. The nonlocal elasticity of Eringen as well as surface effects, including surface elasticity, surface stress and surface density are implemented to inject size-dependent effects into equations. Using the Hamilton's principle and Euler-Bernoulli beam theory, the governing differential equations and associated boundary conditions will be obtained. The differential transformation method (DTM) is used to discretize resultant motion equations and related boundary conditions accordingly. The natural frequencies are obtained for the various elastic boundary conditions in detail to show the significance of nonlocal parameter, external voltage, temperature change, surface effects, elastic medium, magnetic field and length of nanobeam. Moreover, it should be noted that by changing the spring stiffness at each end, the conventional boundary conditions will be obtained which are validated by well-known literature.

  16. Vibrational spectroscopic (FT-IR, FT-Raman) studies, Hirshfeld surfaces analysis, and quantum chemical calculations of m-acetotoluidide and m-thioacetotoluidide

    Science.gov (United States)

    Śmiszek-Lindert, Wioleta Edyta; Chełmecka, Elżbieta; Góralczyk, Stefan; Kaczmarek, Marian

    2017-01-01

    Theoretical calculations of the m-acetotoluidide and m-thioacetotoluidide isolated molecules were performed by using density functional theory (DFT) method at B3LYP/6-311++G (d,p) and B3LYP/6-311++G (3df,2pd) basis set levels. The Hirshfeld surfaces analysis and FT-IR and FT-Raman spectroscopy studies have been reported. The geometrical parameters of the title amide and thioamide are in a good agreement with the XRD experiment. The vibrational frequencies were calculated and scaled, and subsequently values have been compared with the experimental Infrared and Raman spectra. The observed and calculated frequencies are found to be in good agreement. The analysis of the Hirshfeld surface has been well correlated to the spectroscopic studies. Additionally, the highest occupied molecular orbital energy (EHOMO), lowest unoccupied molecular orbital energy (ELUMO) and the energy gap between EHOMO and ELUMO (ΔEHOMO-LUMO) have been calculated.

  17. Non-specific cellular uptake of surface-functionalized quantum dots

    CERN Document Server

    Kelf, T A; Sun, J; Kim, E J; Goldys, E M; Zvyagin, A V; 10.1088/0957-4484/21/28/285105

    2010-01-01

    We report a systematic empirical study of nanoparticle internalization into cells via non-specific pathways. The nanoparticles were comprised of commercial quantum dots (QDs) that were highly visible under a fluorescence confocal microscope. Surface-modified QDs with basic biologically-significant moieties, e.g. carboxyl, amino, streptavidin were used, in combination with the surface derivatization with polyethylene glycol (PEG) in a range of immortalized cell lines. Internalization rates were derived from image analysis and a detailed discussion about the effect of nanoparticle size, charge and surface groups is presented. We find that PEG-derivatization dramatically suppresses the non-specific uptake while PEG-free carboxyl and amine functional groups promote QD internalization. These uptake variations displayed a remarkable consistency across different cell types. The reported results are important for experiments concerned with cellular uptake of surface-functionalized nanomaterials, both when non-specifi...

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

    Science.gov (United States)

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

    2009-02-25

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

  19. The study of pervious concrete mix proportion by the method of specific surface area of aggregate

    Science.gov (United States)

    Xiao, Liguang; Jiang, Dawei

    2017-09-01

    The purpose of this paper is to solve the shortcoming of the mix proportion of pervious concrete. So we have done the research on the measurement of the specific surface area of aggregate, and the research on the volume change of cement after hydration, and the research on the best water-binder ratio and thickness of gelled material package. The experimental results show that the equivalent method is more accurate for measuring the specific surface area of aggregate. It can better reflect the specific surface area of aggregate. Moreover, the calculation method of the mix proportion of the cementing material can improve the utilization ratio of material and the quality of pervious concrete.

  20. Specific features of low-frequency vibrational dynamics and low-temperature heat capacity of double-walled carbon nanotubes

    Science.gov (United States)

    Avramenko, M. V.; Roshal, S. B.

    2016-05-01

    A continuous model has been constructed for low-frequency dynamics of a double-walled carbon nanotube. The formation of the low-frequency part of the phonon spectrum of a double-walled nanotube from phonon spectra of its constituent single-walled nanotubes has been considered in the framework of the proposed approach. The influence of the environment on the phonon spectrum of a single double-walled carbon nanotube has been analyzed. A combined method has been proposed for estimating the coefficients of the van der Waals interaction between the walls of the nanotube from the spectroscopic data and the known values of the elastic moduli of graphite. The low-temperature specific heat has been calculated for doublewalled carbon nanotubes, which in the field of applicability of the model ( T nanotubes forming it.

  1. Neutron Diffraction Studies of the Atomic Vibrations of Bulk and Surface Atoms of Nanocrystalline SiC

    Science.gov (United States)

    Stelmakh, S.; Grzanka, E.; Zhao, Y.; Palosz, W.; Palosz, B.

    2004-01-01

    Thermal atomic motions of nanocrystalline Sic were characterized by two temperature atomic factors B(sub core), and B(sub shell). With the use of wide angle neutron diffraction data it was shown that at the diffraction vector above 15A(exp -1) the Wilson plots gives directly the temperature factor of the grain interior (B(sub core)). At lower Q values the slope of the Wilson plot provides information on the relative amplitudes of vibrations of the core and shell atoms.

  2. A process to enhance the specific surface area and capacitance of hydrothermally reduced graphene oxide

    KAUST Repository

    Alazmi, Amira

    2016-08-26

    The impact of post-synthesis processing in reduced graphene oxide materials for supercapacitor electrodes has been analyzed. A comparative study of vacuum, freeze and critical point drying was carried out for hydrothermally reduced graphene oxide demonstrating that the optimization of the specific surface area and preservation of the porous network are critical to maximize its supercapacitance performance. As described below, using a supercritical fluid as the drying medium, unprecedented values of the specific surface area (364 m2 g−1) and supercapacitance (441 F g−1) for this class of materials have been achieved.

  3. Preparation of Zirconia-Ceria Powders with High Specific Surface Area

    Institute of Scientific and Technical Information of China (English)

    Wang Enguo; Mei Fang

    2004-01-01

    Zirconia-ceria mixed oxide powders were prepared by high temperature aging method.The effects of the temperature and the time of aging, cerium content and calcination on powder performance were studied.The result shows that high temperature aging is an efficient way of preparation of ZrO2-CeO2 mixed oxide powders with high specific surface area and good thermal stability, and that addition of a small amount of cerium to hydrous zirconia can promote the preparation of high specific surface area powders.

  4. The clusters-in-a-liquid approach for solvation: New insights from the conformer specific gas phase spectroscopy and vibrational optical activity spectroscopy

    Directory of Open Access Journals (Sweden)

    Yunjie eXu

    2016-02-01

    Full Text Available Vibrational optical activity spectroscopies, namely vibrational circular dichroism (VCD and Raman optical activity (ROA, have been emerged in the past decade as a powerful spectroscopic tool for stereochemical information of a wide range of chiral compounds in solution directly. More recently, their applications in unveiling solvent effects, especially those associated with water solvent, have been explored. In this review article, we first select a few examples to demonstrate the unique sensitivity of VCD spectral signatures to both bulk solvent effects and explicit hydrogen-bonding interactions in solution. Second, we discuss the induced solvent chirality, or chiral transfer, VCD spectral features observed at the water bending band region in detail. From these chirality transfer spectral data, the related conformer specific gas phase spectroscopic studies of small chiral hydration clusters, and the associated matrix isolation VCD experiments of hydrogen-bonded complexes in cold rare gas matrices, a general picture of solvation in aqueous solution emerges. In such an aqueous solution, some small chiral hydration clusters, rather than the chiral solutes themselves, are the dominant species and are the ones who contribute mainly to the experimentally observed VCD features. We then review a series of VCD studies of amino acids and their derivatives in aqueous solution under different pHs to emphasize the importance of the inclusion of the bulk solvent effects. These experimental data and the associated theoretical analyses are the foundation for the proposed clusters-in-a-liquid approach to account for solvent effects effectively. We present several approaches to identify and build such representative chiral hydration clusters. Recent studies which applied molecular dynamics simulations and the subsequent snapshot averaging approach to generate the ROA, electronic CD, and optical rotatory dispersion spectra are also reviewed. Challenges associated

  5. Electrical transport properties of graphene on SiO2 with specific surface structures

    OpenAIRE

    Nagashio, K.; Yamashita, T; Nishimura, T.; K. Kita; Toriumi, A.

    2011-01-01

    The mobility of graphene transferred on a SiO2/Si substrate is limited to ~10,000 cm2/Vs. Without understanding the graphene/SiO2 interaction, it is difficult to improve the electrical transport properties. Although surface structures on SiO2 such as silanol and siloxane groups are recognized, the relation between the surface treatment of SiO2 and graphene characteristics has not yet been elucidated. This paper discusses the electrical transport properties of graphene on specific surface stru...

  6. New developments for the site-specific attachment of protein to surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Camarero, J A

    2005-05-12

    Protein immobilization on surfaces is of great importance in numerous applications in biology and biophysics. The key for the success of all these applications relies on the immobilization technique employed to attach the protein to the corresponding surface. Protein immobilization can be based on covalent or noncovalent interaction of the molecule with the surface. Noncovalent interactions include hydrophobic interactions, hydrogen bonding, van der Waals forces, electrostatic forces, or physical adsorption. However, since these interactions are weak, the molecules can get denatured or dislodged, thus causing loss of signal. They also result in random attachment of the protein to the surface. Site-specific covalent attachment of proteins onto surfaces, on the other hand, leads to molecules being arranged in a definite, orderly fashion and uses spacers and linkers to help minimize steric hindrances between the protein surface. This work reviews in detail some of the methods most commonly used as well as the latest developments for the site-specific covalent attachment of protein to solid surfaces.

  7. Specific bindings of glycine peptides of distinctly different chain length on dynamic papain surfaces

    Science.gov (United States)

    Nishiyama, Katsuhiko

    2011-06-01

    We investigated the specific bindings of peptides of 1-10 glycine residues (1-10GLY) on dynamic papain surfaces via molecular dynamics and docking simulations. Although the binding specificities of 1-5GLY on papain fluctuated little with time, the binding specificities of 6-10GLY on papain considerably fluctuated with time. Some residues had a significant impact on bindings of 6-10GLY to sites near active center of papain, and some of their residues were specific for each 6GLY, 8GLY, and 10GLY. Modification of these specific residues should allow for control of binding specificity of 6GLY, 8GLY, and 10GLY to the active center.

  8. Waves & vibrations

    OpenAIRE

    Nicolas, Maxime

    2016-01-01

    Engineering school; This course is designed for students of Polytech Marseille, engineering school. It covers first the physics of vibration of the harmonic oscillator with damping and forcing, coupled oscillators. After a presentation of the wave equation, the vibration of strings, beams and membranes are studied.

  9. Specific grinding energy and surface roughness of nanoparticle jet minimum quantity lubrication in grinding

    Directory of Open Access Journals (Sweden)

    Zhang Dongkun

    2015-04-01

    Full Text Available Nanoparticles with the anti-wear and friction reducing features were applied as cooling lubricant in the grinding fluid. Dry grinding, flood grinding, minimal quantity of lubrication (MQL, and nanoparticle jet MQL were used in the grinding experiments. The specific grinding energy of dry grinding, flood grinding and MQL were 84, 29.8, 45.5 J/mm3, respectively. The specific grinding energy significantly decreased to 32.7 J/mm3 in nanoparticle MQL. Compared with dry grinding, the surface roughness values of flood grinding, MQL, and nanoparticle jet MQL were significantly reduced with the surface topography profile values reduced by 11%, 2.5%, and 10%, respectively, and the ten point height of microcosmic unflatness values reduced by 1.5%, 0.5%, and 1.3%, respectively. These results verified the satisfactory lubrication effects of nanoparticle MQL. MoS2, carbon nanotube (CNT, and ZrO2 nanoparticles were also added in the grinding fluid of nanoparticle jet MQL to analyze their grinding surface lubrication effects. The specific grinding energy of MoS2 nanoparticle was only 32.7 J/mm3, which was 8.22% and 10.39% lower than those of the other two nanoparticles. Moreover, the surface roughness of workpiece was also smaller with MoS2 nanoparticle, which indicated its remarkable lubrication effects. Furthermore, the role of MoS2 particles in the grinding surface lubrication at different nanoparticle volume concentrations was analyzed. MoS2 volume concentrations of 1%, 2%, and 3% were used. Experimental results revealed that the specific grinding energy and the workpiece surface roughness initially increased and then decreased as MoS2 nanoparticle volume concentration increased. Satisfactory grinding surface lubrication effects were obtained with 2% MoS2 nanoparticle volume concentration.

  10. Studies Of Vibrations In Gearboxes

    Science.gov (United States)

    Choy, Fred K.; Ruan, Yeefeng F.; Tu, Yu K.; Zakrajsek, James J.; Oswald, Fred B.; Coy, John J.; Townsend, Dennis P.

    1994-01-01

    Three NASA technical memorandums summarize studies of vibrations in gearboxes. Directed toward understanding and reducing gearbox noise caused by coupling of vibrations from meshing gears, through gear shafts and their bearings, to surfaces of gearbox housings. Practical systems in which understanding and reduction of gearbox noise beneficial include helicopter, car, and truck transmissions; stationary geared systems; and gear-driven actuator systems.

  11. Isolating Site-Specific Spectral Signatures of Individual Water Molecules in H-Bonded Networks with Isotopomer-Selective Ir-Ir Double Resonance Vibrational Predissociation Spectroscopy

    Science.gov (United States)

    Wolke, Conrad T.; Johnson, Mark

    2016-06-01

    We will discuss an experimental method that directly yields the embedded correlations between the two OH stretches and the intramolecular bending modes associated with a single H2O water molecule embedded in an otherwise all-D isotopologue. This is accomplished using isotopomer-selective IR-IR hole-burning on the Cs+(D2O)5(H2O) clusters formed by gas-phase exchange of a single, intact H2O molecule for D2O in the Cs+(D2O)6 ion. The OH stretching pattern of the Cs+(H2O)6 isotopologue is accurately recovered by superposition of the isotopomer spectra, thus establishing that the H2O incorporation is random and that the OH stretching manifold is largely due to contributions from decoupled water molecules. This behavior enables a powerful new way to extract structural information from vibrational spectra of size-selected clusters by explicitly identifying the local environments responsible for specific infrared features. Extension of this method to address the degree to which OH stretches are decoupled in the protonated water clusters will also be discussed.

  12. Mode-specific vibrational relaxation of photoexcited guanosine 5'-monophosphate and its acid form: a femtosecond broadband mid-IR transient absorption and theoretical study.

    Science.gov (United States)

    Zhang, Yuyuan; Improta, Roberto; Kohler, Bern

    2014-01-28

    UV-pump/broadband-mid-IR-probe transient absorption (TA) experiments and ab initio quantum mechanical (QM) calculations were used to investigate the photophysics in heavy water of the neutral and acid forms of guanosine 5'-monophosphate (GMP and GMPD(+), respectively). Excited GMP undergoes ultrafast internal conversion (IC) and returns to the electronic ground state in less than one picosecond with a large amount of excess vibrational energy. The spectroscopic signals are dominated by vibrational cooling - a process in which the solute dissipates vibrational energy to the solvent. For neutral GMP, cooling proceeds with a time constant of 3 ps. Following IC, at least some medium-frequency modes such as the carbonyl stretch and an in-plane ring vibration are excited, suggesting that the vibrational energy distribution is non-statistical. This is consistent with predicted structural changes upon passage through the S1/S0 conical intersection. GMPD(+) differs from GMP by a single deuteron at the N7 position, but has a dramatically longer lifetime of 200 ps. Vibrational cooling of the S1 state of GMPD(+) was monitored via several medium-frequency modes that were assigned using QM calculations. These medium-frequency modes are also vibrationally excited in a non-statistical fashion. Excitation of these modes is in line with the change in geometry at the S1 minimum of GMPD(+) predicted by QM calculations. Furthermore, these modes relax at different rates, fully consistent with QM calculations, which predict that excited vibrational states of the carbonyl stretch couple strongly to the D2O solvent and thus deactivate via intermolecular energy transfer (IET). In contrast, the ring stretch couples strongly to other ring modes of the guanine chromophore and appears to decay via intramolecular vibrational energy redistribution (IVR).

  13. Universality and Specificity of Fractal Dimension of Fractured Surfaces in Materials

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    After calculation on the fracture angles under various conditions of specific surface energies with different symmetry operations of rotation, the complicated behavior of dependence of fractal dimension on the structure of crystal is shown. It is found that the crack propagates along the weakest crystal plane no matter what the direction of the maximum stress is if the anisotropy is sufficiently strong; and then, the fractal dimension of the fractured surfaces might be determined by the approximate fractal structure already existed in the material. Specificity of the fractal dimension of fractured surfaces would be easy to appear in this case. Reversely, the crack propagates along the direction of the maximum stress no matter what direction of the weakest crystal plane is if the anisotropy is sufficiently weak. Universality of the fractal dimension of fractured surfaces would be possible to appear in this case. In many real materials, universality and specificity of the materials are associated. The fractal dimension measured may more or less be influenced by the structure of materials and it shows its universality through the specificity of materials.

  14. Specific surface area effect on adsorption of chlorpyrifos and TCP by soils and modeling

    Science.gov (United States)

    The adsorption of chlorpyrifos and TCP (3,5,6, trichloro-2-pyridinol) was determined in four soils (Mollisol, Inceptisol, Entisol, Alfisol) having different specific surface areas (19–84 m2/g) but rather similar organic matter content (2.4–3.5%). Adsorption isotherms were derived from batch equilibr...

  15. Production of specific structured lipids by enzymatic interesterification: optimization of the reaction by response surface design

    DEFF Research Database (Denmark)

    Xu, Xuebing; Skands, Anja Rebecca Havegaard; Adler-Nissen, Jens;

    1998-01-01

    Rapeseed oil and capric acid were interesterified in solvent-free media catalyzed by Lipozyme IM (Rhizomucor miehei) to produce specific-structured lipids (SSLs). The process was optimized by response surface design concerning the effects of acyl migration and the by-products of diacylglycerols...

  16. Specific surface modification of the acetylene-linked glycolipid vesicle by click chemistry.

    Science.gov (United States)

    Ito, Hidehiro; Kamachi, Toshiaki; Yashima, Eiji

    2012-06-07

    A novel glycolipid with a terminal acetylene was synthesized and used to prepare unilamellar vesicles. Using these vesicles, a convenient method was developed for the specific modification of the vesicle surface using the photoresponsive copper complex [Cu(OH(2))(cage)] as the catalyst for a click reaction.

  17. Vibrations on board and health effects

    DEFF Research Database (Denmark)

    Jensen, Anker; Jepsen, Jørgen Riis

    2014-01-01

    There is only limited knowledge of the exposure to vibrations of ships’ crews and their risk of vibration-induced health effects. Exposure to hand-arm vibrations from the use of vibrating tools at sea does not differ from that in the land-based trades. However, in contrast to most other work places......, seafarers are also exposed to vibrations to the feet when standing on vibrating surfaces onboard. Anecdotal reports have related the development of “white feet” to local exposure to vibration, e.g. in mining, but this connection has not been investigated in the maritime setting. As known from studies...... of the health consequences of whole body vibrations in land-transportation, such exposure at sea may affect ships’ passengers and crews. While the relation of back disorders to high levels of whole body vibration has been demonstrated among e.g. tractor drivers, there are no reported epidemiological evidence...

  18. Understanding the interfacial properties of nanostructured liquid crystalline materials for surface-specific delivery applications.

    Science.gov (United States)

    Dong, Yao-Da; Larson, Ian; Barnes, Timothy J; Prestidge, Clive A; Allen, Stephanie; Chen, Xinyong; Roberts, Clive J; Boyd, Ben J

    2012-09-18

    Nonlamellar liquid crystalline dispersions such as cubosomes and hexosomes have great potential as novel surface-targeted active delivery systems. In this study, the influence of internal nanostructure, chemical composition, and the presence of Pluronic F127 as a stabilizer, on the surface and interfacial properties of different liquid crystalline particles and surfaces, was investigated. The interfacial properties of the bulk liquid crystalline systems with coexisting excess water were dependent on the internal liquid crystalline nanostructure. In particular, the surfaces of the inverse cubic systems were more hydrophilic than that of the inverse hexagonal phase. The interaction between F127 and the bulk liquid crystalline systems depended on the internal liquid crystalline structure and chemical composition. For example, F127 adsorbed to the surface of the bulk phytantriol cubic phase, while for monoolein cubic phase, F127 was integrated into the liquid crystalline structure. Last, the interfacial adsorption behavior of the dispersed liquid crystalline particles also depended on both the internal nanostructure and the chemical composition, despite the dispersions all being stabilized using F127. The findings highlight the need to understand the specific surface characteristics and the nature of the interaction with colloidal stabilizer for understanding and optimizing the behavior of nonlamellar liquid crystalline systems in surface delivery applications.

  19. Non-specific cellular uptake of surface-functionalized quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Kelf, T A; Sreenivasan, V K A; Sun, J; Goldys, E M; Zvyagin, A V [MQ Photonics Centre, Faculty of Science, Macquarie University, Sydney (Australia); Kim, E J, E-mail: azvyagin@science.mq.edu.au [Department of Science Education-Chemical Education Major, Daegu University, Gyeonbuk (Korea, Republic of)

    2010-07-16

    We report a systematic empirical study of nanoparticle internalization into cells via non-specific pathways. The nanoparticles were comprised of commercial quantum dots (QDs) that were highly visible under a fluorescence confocal microscope. Surface-modified QDs with basic biologically significant moieties, e.g. carboxyl, amino, and streptavidin, were used, in combination with surface derivatization with polyethylene glycol (PEG) for a range of immortalized cell lines. Internalization rates were derived from image analysis and a detailed discussion about the effect of nanoparticle size, charge and surface groups is presented. We find that PEG derivatization dramatically suppresses the non-specific uptake while PEG-free carboxyl and amine functional groups promote QD internalization. These uptake variations displayed a remarkable consistency across different cell types. The reported results are important for experiments concerned with cellular uptake of surface-functionalized nanomaterials, both when non-specific internalization is undesirable and when it is intended for material to be internalized as efficiently as possible.

  20. Part 2: effect of training surface on acute physiological responses after sport-specific training.

    Science.gov (United States)

    Binnie, Martyn J; Dawson, Brian; Pinnington, Hugh; Landers, Grant; Peeling, Peter

    2013-04-01

    This study compared the effect of sand and grass training surfaces during a sport-specific conditioning session in well-trained team sport athletes (n = 10). The participants initially completed a preliminary testing session to gather baseline (BASE) performance data for vertical jump, repeated sprint ability, and 3-km running time trial. Three days subsequent to BASE, all the athletes completed the first sport-specific conditioning session, which was followed by a repeat of the BASE performance tests the following day (24 hours postexercise). Seven days later, the same training session was completed on the opposing surface and was again followed 24 hours later by the BASE performance tests. During each session, blood lactate, ratings of perceived exertion (RPE), and heart rate (HR) were recorded, with player movement patterns also monitored via global positioning system units. Additionally, venous blood was collected preexercise, postexercise, and 24 hours postexercise, and analyzed for serum concentrations of Myoglobin, Haptoglobin, and C-Reactive Protein. Results showed significantly higher HR and RPE responses on SAND (p > 0.05), despite significantly lower distance and velocity outputs for the training session (p > 0.05). There were no differences in 24 hours postexercise performance (p > 0.05), and blood markers of muscle damage, inflammation and hemolysis were also similar between the surfaces (p > 0.05). These results suggest that performing a sport-specific conditioning session on a sand (vs. grass) surface can result in a greater physiological response, without any additional decrement to next-day performance.

  1. Exploring site-specific chemical interactions at surfaces: a case study on highly ordered pyrolytic graphite

    Science.gov (United States)

    Dagdeviren, Omur E.; Götzen, Jan; Altman, Eric I.; Schwarz, Udo D.

    2016-12-01

    A material’s ability to interact with approaching matter is governed by the structural and chemical nature of its surfaces. Tailoring surfaces to meet specific needs requires developing an understanding of the underlying fundamental principles that determine a surface’s reactivity. A particularly insightful case occurs when the surface site exhibiting the strongest attraction changes with distance. To study this issue, combined noncontact atomic force microscopy and scanning tunneling microscopy experiments have been carried out, where the evolution of the local chemical interaction with distance leads to a contrast reversal in the force channel. Using highly ordered pyrolytic graphite surfaces and metallic probe tips as a model system, we find that at larger tip-sample distances, carbon atoms exhibit stronger attractions than hollow sites while upon further approach, hollow sites become energetically more favorable. For the tunneling current that is recorded at large tip-sample separations during acquisition of a constant-force image, the contrast is dominated by the changes in tip-sample distance required to hold the force constant (‘cross-talk’) at smaller separations the contrast turns into a convolution of this cross-talk and the local density of states. Analysis shows that the basic factors influencing the force channel contrast reversal are locally varying decay lengths and an onset of repulsive forces that occurs for distinct surface sites at different tip-sample distances. These findings highlight the importance of tip-sample distance when comparing the relative strength of site-specific chemical interactions.

  2. Characterization of homing endonuclease binding and cleavage specificities using yeast surface display SELEX (YSD-SELEX).

    Science.gov (United States)

    Jacoby, Kyle; Lambert, Abigail R; Scharenberg, Andrew M

    2017-02-17

    LAGLIDADG homing endonucleases (LHEs) are a class of rare-cleaving nucleases that possess several unique attributes for genome engineering applications. An important approach for advancing LHE technology is the generation of a library of design ‘starting points’ through the discovery and characterization of natural LHEs with diverse specificities. However, while identification of natural LHE proteins by sequence homology from genomic and metagenomic sequence databases is straightforward, prediction of corresponding target sequences from genomic data remains challenging. Here, we describe a general approach that we developed to circumvent this issue that combines two technologies: yeast surface display (YSD) of LHEs and systematic evolution of ligands via exponential enrichment (SELEX). Using LHEs expressed on the surface of yeast, we show that SELEX can yield binding specificity motifs and identify cleavable LHE targets using a combination of bioinformatics and biochemical cleavage assays. This approach, which we term YSD-SELEX, represents a simple and rapid first principles approach to determining the binding and cleavage specificity of novel LHEs that should also be generally applicable to any type of yeast surface expressible DNA-binding protein. In this marriage, SELEX adds DNA specificity determination to the YSD platform, and YSD brings diagnostics and inexpensive, facile protein-matrix generation to SELEX.

  3. Specific adsorption of tungstate by cell surface display of the newly designed ModE mutant.

    Science.gov (United States)

    Kuroda, Kouichi; Nishitani, Takashi; Ueda, Mitsuyoshi

    2012-10-01

    By cell surface display of ModE protein that is a transcriptional regulator of operons involved in the molybdenum metabolism in Escherichia coli, we have constructed a molybdate-binding yeast (Nishitani et al., Appl Microbiol Biotechnol 86:641-648, 2010). In this study, the binding specificity of the molybdate-binding domain of the ModE protein displayed on yeast cell surface was improved by substituting the amino acids involved in oxyanion binding with other amino acids. Although the displayed S126T, R128E, and T163S mutant proteins adsorbed neither molybdate nor tungstate, the displayed ModE mutant protein (T163Y) abolished only molybdate adsorption, exhibiting the specific adsorption of tungstate. The specificity of the displayed ModE mutant protein (T163Y) for tungstate was increased by approximately 9.31-fold compared to the displayed wild-type ModE protein at pH 5.4. Therefore, the strategy of protein design and its cell surface display is effective for the molecular breeding of bioadsorbents with metal-specific adsorption ability based on a single species of microorganism without isolation from nature.

  4. The triazine-based porous organic polymer: Novel synthetic strategy for high specific surface area

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jin Kuen [Dept. of Chemistry, Hankuk University of Foreign Studies, Yongin (Korea, Republic of)

    2017-02-15

    A new type of microporous polymer has been successively synthesized via a simple polycondensation reaction with the 2,4-diaminotriazine moiety and dianhydride monomer. Diaminotriazine moieties in M1 especially can provide effective branching sites, resulting in high surface areas up to 1150 m{sup 2} /g. In addition, the specific pore structure of the polyimide POP in its solid state can be modified by the surface activation method. Therefore, it can be expected that the resulting material will be a promising candidate for gas storage, and with this synthetic strategy, various type of derivatives will also be optimized.

  5. Nano surface interaction and mo del of vibrating prob e%纳米表面相互作用及振动测头模型∗

    Institute of Scientific and Technical Information of China (English)

    陈丽娟; 陈晓怀; 刘芳芳; 王景凡

    2016-01-01

    The high precision measurement has been a focus in the field of manufacturing and microelectronics in this year. The micro/nano probe for coordinate measuring machine (CMM) acts as a key characteristic because it can measure the high-aspect-ratio components with high precision. Various micro/nano-CMM probes with different principles and different structures have been developed in the last decade. However, most of these studies focused on the sensing principle and measurement methods. There is little research on the behavior of the surface interaction between the probe tip and the workpiece. And the measurement accuracy and reliability of the current probe, especially those of the low stiffness probe, are limited by interaction forces including capillary force, van der Waals force, electrostatic force and Casimir force. Therefore, it becomes a challenge to reduce the effect of the surface interaction forces for the Micro/nano CMM probe. A new trigger probe based on the vibrating principle is analyzed and an optimal method for the appropriate vibrating parameters is presented in this paper. The structure and principle of the probe are briefly described in the first part. In this system, a tungsten stylus with a tip-ball is fixed to the floating plate, which is supported by four L-shape high-elasticity leaf springs. The fiber Bargg grating (FBG) sensors are used in the probe for micro-CMM due to their superiority in t of small size, high sensitivity, large linear measuring range, immunity to electromagnetic interference, and low cost. One end of FBG is attached to a floating plate, and the other end to a retention plate which is connected with the piezoelectric ceramic actuator (PZT). The probe is driven by the PZT vibrating. Assuming that the driving forces can offset the surface interaction forces, then the probe can be described as a forced vibration model of the spring oscillator. Therefore, the equivalent model of the probe is set up. In the second part, a

  6. Surface enhanced vibrational spectroscopy and first-principles study of L-cysteine adsorption on noble trimetallic Au/Pt@Rh clusters.

    Science.gov (United States)

    Loganathan, B; Chandraboss, V L; Senthilvelan, S; Karthikeyan, B

    2015-09-07

    The Rh shell of the Au/Pt/Rh trimetallic nanoparticles induces a wide variety of interesting surface reactions by allowing the adsorption of amino acids like L-cysteine (L-Cys). We present a snapshot of theoretical and experimental investigation of L-Cys adsorption on the surface of noble trimetallic Au/Pt@Rh colloidal nanocomposites. Density functional theoretical (DFT) investigations of L-Cys interaction with the Rhodium (Rh) shell of a trimetallic Au/Pt@Rh cluster in terms of geometry, binding energy (E(B)), binding site, energy gap (E(g)), electronic and spectral properties have been performed. L-Cys establishes a strong interaction with the Rh shell. It binds to Rh by the S1-site, which makes a stable L-Cys-Rh surface complex. DFT can be taken as a valuable tool to assign the vibrational spectra of the adsorption of L-Cys on trimetallic Au/Pt@Rh colloidal nanocomposites and mono-metallic Rh nanoparticles. Surface-enhanced infrared spectroscopy (SEIRS) with L-Cys on a Rh6 cluster surface has been simulated for the first time. Experimental information on the L-Cys-Rh surface complex is included to examine the interaction. The experimental spectral observations are in good agreement with the simulated DFT results. Characterization of the synthesized trimetallic Au/Pt@Rh colloidal nanocomposites has been done by high-resolution transmission electron microscopy (HR-TEM) with selected area electron diffraction (SAED) pattern, energy dispersive X-ray (EDX) spectroscopy, dynamic light scattering (DLS) measurements, zeta potential, zeta deviation analysis and UV-visible (UV-Vis) spectroscopic studies.

  7. Effect of surface related organic vibrational modes in luminescent upconversion dynamics of rare earth ions doped nanoparticles

    NARCIS (Netherlands)

    Wang, Y.; Smolarek, S.; Kong, X.; Buma, W.J.; Brouwer, A.M.; Zhang, H.

    2010-01-01

    Physical and chemical properties of nanoparticles are known to be subject to the surface factors. For their biological/biomedical applications, typically, surface of the nanoparticles has to be modified which inevitably affects their performance. In this work we have studied the interaction between

  8. Surface-enhanced vibrational spectroscopy of B vitamins: what is the effect of SERS-active metals used?

    Science.gov (United States)

    Kokaislová, A; Matějka, P

    2012-05-01

    Surface-enhanced Raman scattering (SERS) spectroscopy and surface-enhanced infrared absorption (SEIRA) spectroscopy are analytical tools suitable for the detection of small amounts of various analytes adsorbed on metal surfaces. During recent years, these two spectroscopic methods have become increasingly important in the investigation of adsorption of biomolecules and pharmaceuticals on nanostructured metal surfaces. In this work, the adsorption of B-group vitamins pyridoxine, nicotinic acid, folic acid and riboflavin at electrochemically prepared gold and silver substrates was investigated using Fourier transform SERS spectroscopy at an excitation wavelength of 1,064 nm. Gold and silver substrates were prepared by cathodic reduction on massive platinum targets. In the case of gold substrates, oxidation-reduction cycles were applied to increase the enhancement factor of the gold surface. The SERS spectra of riboflavin, nicotinic acid, folic acid and pyridoxine adsorbed on silver substrates differ significantly from SERS spectra of these B-group vitamins adsorbed on gold substrates. The analysis of near-infrared-excited SERS spectra reveals that each of B-group vitamin investigated interacts with the gold surface via a different mechanism of adsorption to that with the silver surface. In the case of riboflavin adsorbed on silver substrate, the interpretation of surface-enhanced infrared absorption (SEIRA) spectra was also helpful in investigation of the adsorption mechanism.

  9. Good Vibrations

    OpenAIRE

    Panesar, Lucy

    2007-01-01

    Good Vibrations was a market research exercise conducted by Felicity (my alter-ego) and assistants to help develop marketing and packaging for an electro-therapeutic device (vibrator) used to treat hysteria and other female stress related disorders. It was a live art work commissioned by The Live Art Development Agency for East End Collaborations on 6th May 2007 and the South London Gallery for Bonkersfest on 2nd June 2007.

  10. Tibiofemoral joint subchondral surface conformity: Individual variability with race and sex-specific trends.

    Science.gov (United States)

    Everhart, Joshua S; Flanigan, David C; Chaudhari, Ajit M W; Siston, Robert A

    2016-10-01

    Femoral and tibial subchondral surface morphology has been extensively studied to aid in anatomically correct total knee arthroplasty (TKA) implant design. Emphasis has been placed on shape variations in individual bones, and person-to-person variability in joint conformity has been overlooked. The purpose of this study is to 1) determine individual variability in key measures of tibiofemoral joint conformity, and 2) determine whether variability differs by sex or race. Laser-scanner-generated surface models of tibiofemoral joints were obtained from 165 archival skeletons (at death: age 28.8±7.6years; 85 African-American, 80 Caucasian, 86 men, 79 women). Ratios and correlations were determined among related femoral and tibial subchondral surface areas (SA), alignment, curvatures, and linear dimensions between opposing surfaces with stratification by race and sex. Anterior-posterior length (R=0.80, pconformity at the subchondral surface, and for some measures this variability is sex-or-race specific. Key measures of joint conformity including surface area, curvature, width, and depth covary weakly or not at all, and a wide range of TKA component sizes and shapes would be required to accurately replicate native joint conformity in most people. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Vibration sensors

    Science.gov (United States)

    Gupta, Amita; Singh, Ranvir; Ahmad, Amir; Kumar, Mahesh

    2003-10-01

    Today, vibration sensors with low and medium sensitivities are in great demand. Their applications include robotics, navigation, machine vibration monitoring, isolation of precision equipment & activation of safety systems e.g. airbags in automobiles. Vibration sensors have been developed at SSPL, using silicon micromachining to sense vibrations in a system in the 30 - 200 Hz frequency band. The sensing element in the silicon vibration sensor is a seismic mass suspended by thin silicon hinges mounted on a metallized glass plate forming a parallel plate capacitor. The movement of the seismic mass along the vertical axis is monitored to sense vibrations. This is obtained by measuring the change in capacitance. The movable plate of the parallel plate capacitor is formed by a block connected to a surrounding frame by four cantilever beams located on sides or corners of the seismic mass. This element is fabricated by silicon micromachining. Several sensors in the chip sizes 1.6 cm x 1.6 cm, 1 cm x 1 cm and 0.7 cm x 0.7 cm have been fabricated. Work done on these sensors, techniques used in processing and silicon to glass bonding are presented in the paper. Performance evaluation of these sensors is also discussed.

  12. Specific heats of lunar surface materials from 90 to 350 degrees Kelvin

    Science.gov (United States)

    Robie, R.A.; Hemingway, B.S.; Wilson, W.H.

    1970-01-01

    The specific heats of lunar samples 10057 and 10084 returned by the Apollo 11 mission have been measured between 90 and 350 degrees Kelvin by use of an adiabatic calorimeter. The samples are representative of type A vesicular basalt-like rocks and of finely divided lunar soil. The specific heat of these materials changes smoothly from about 0.06 calorie per gram per degree at 90 degrees Kelvin to about 0.2 calorie per gram per degree at 350 degrees Kelvin. The thermal parameter ??=(k??C)-1/2 for the lunar surface will accordingly vary by a factor of about 2 between lunar noon and midnight.

  13. Correlation of Gear Surface Fatigue Lives to Lambda Ratio (Specific Film Thickness)

    Science.gov (United States)

    Krantz, Timothy Lewis

    2013-01-01

    The effect of the lubrication regime on gear performance has been recognized, qualitatively, for decades. Often the lubrication regime is characterized by the specific film thickness being the ratio of lubricant film thickness to the composite surface roughness. Three studies done at NASA to investigate gearing pitting life are revisited in this work. All tests were done at a common load. In one study, ground gears were tested using a variety of lubricants that included a range of viscosities, and therefore the gears operated with differing film thicknesses. In a second and third study, the performance of gears with ground teeth and superfinished teeth were assessed. Thicker oil films provided longer lives as did improved surface finish. These datasets were combined into a common dataset using the concept of specific film thickness. This unique dataset of more 258 tests provides gear designers with some qualitative information to make gear design decisions.

  14. Preparation and characterization of boron nitride/carbon fiber composite with high specific surface area

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Yan; Fan, Mingwen [Wuhan Univ. (China). Key Laboratory for Oral Biomedical Engineering; Yuan, Songdong; Xiong, Kun; Hu, Kunpeng; Luo, Yi [Hubei Univ. of Technology, Wuhan (China). School of Chemistry and Chemical Engineering; Li, Dong [Hubei Univ. of Technology, Wuhan (China). School of Chemistry and Chemical Engineering; Oxford Univ. (United Kingdom). Chemistry Research Lab.

    2014-06-15

    Boron nitride can be used as a good catalyst carrier because of its high thermal conductivity and chemical stability. However, a high specific surface area of boron nitride is still desirable. In this work, a carbon fiber composite coated with boron nitride villous nano-film was prepared, and was also characterized by means of scanning electron microscopy, high resolution transmission electron microscopy, Fourier transform infrared spectroscopy, and Brunauer-Emmett-Teller analysis. The results indicated that the carbon fibers were covered by uniform villous boron nitride films whose thickness was about 150 - 200 nm. The specific surface area of the boron nitride/carbon fiber composite material was 96 m{sup 2} g{sup -1}, which was markedly improved compared with conventional boron nitride materials. (orig.)

  15. Hydration Repulsion between Carbohydrate Surfaces Mediated by Temperature and Specific Ions

    Science.gov (United States)

    Chen, Hsieh; Cox, Jason R.; Ow, Hooisweng; Shi, Rena; Panagiotopoulos, Athanassios Z.

    2016-06-01

    Stabilizing colloids or nanoparticles in solution involves a fine balance between surface charges, steric repulsion of coating molecules, and hydration forces against van der Waals attractions. At high temperature and electrolyte concentrations, the colloidal stability of suspensions usually decreases rapidly. Here, we report a new experimental and simulation discovery that the polysaccharide (dextran) coated nanoparticles show ion-specific colloidal stability at high temperature, where we observed enhanced colloidal stability of nanoparticles in CaCl2 solution but rapid nanoparticle-nanoparticle aggregation in MgCl2 solution. The microscopic mechanism was unveiled in atomistic simulations. The presence of surface bound Ca2+ ions increases the carbohydrate hydration and induces strongly polarized repulsive water structures beyond at least three hydration shells which is farther-reaching than previously assumed. We believe leveraging the binding of strongly hydrated ions to macromolecular surfaces represents a new paradigm in achieving absolute hydration and colloidal stability for a variety of materials, particularly under extreme conditions.

  16. Anti-fouling poly(2-hydoxyethyl methacrylate) surface coatings with specific bacteria recognition capabilities

    Science.gov (United States)

    Mrabet, Bechir; Nguyen, Minh Ngoc; Majbri, Aymen; Mahouche, Samia; Turmine, Mireille; Bakhrouf, Amina; Chehimi, Mohamed M.

    2009-08-01

    Poly(2-hydroxyethyl methacrylate), PHEMA, brushes were prepared by surface-initiated atom transfer radical polymerization (SI-ATRP) on silanized glass slides bearing grafted initiators. High resolution X-ray photoelectron spectroscopy (XPS) highlighted the surface chemical changes of the glass slides upon silanization and surface-confined ATRP of HEMA. Particularly, the initiator sites from the silane were detected by their bromine Br3d core electron peak whilst the O/C atomic ratios and the high resolution C1s region of the glass-PHEMA hybrids are comparable to those of pure PHEMA, thus confirming that the PHEMA chains have indeed attached to the surface. The glass-PHEMA hybrids were found to behave as anti-fouling ultrathin coatings as they resisted non-specific Salmonella typhimurium bacterial adhesion. This behaviour is driven by the hydrophilic properties of the glass-PHEMA hybrids which were assessed by contact angle measurements. In contrast, after activation of PHEMA brushes by S.typhimurium antibodies through the trichlorotriazine coupling procedure, the bacteria specifically and strongly attached to the PHEMA-coated glass slides as judged from optical microscope observation.

  17. Selective radiolabeling of cell surface proteins to a high specific activity

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, J.A.; Lau, A.L.; Cunningham, D.D.

    1987-02-10

    A procedure was developed for selective radiolabeling of membrane proteins on cells to higher specific activities than possible with available techniques. Cell surface amino groups were derivatized with /sup 125/I-(hydroxyphenyl)propionyl groups via /sup 125/I-sulfosuccinimidyl (hydroxyphenyl)propionate (/sup 125/II-sulfo-SHPP). This reagent preferentially labeled membrane proteins exposed at the cell surface of erythrocytes as assessed by the degree of radiolabel incorporation into erythrocyte ghost proteins and hemoglobin. Comparison with the lactoperoxidase-(/sup 125/I)iodide labeling technique revealed that /sup 125/I-sulfo-SHPP labeled cell surface proteins to a much higher specific activity and hemoglobin to a much lower specific activity. Additionally, this reagent was used for selective radiolabeling of membrane proteins on the cytoplasmic face of the plasma membrane by blocking exofacial amino groups with uniodinated sulfo-SHPP, lysing the cells, and then incubating them with /sup 125/I-sulfo-SHPP. Exclusive labeling of either side of the plasma membrane was demonstrated by the labeling of some marker proteins with well-defined spacial orientations on erythroctyes. Transmembrane proteins such as the epidermal growth factor receptor on cultured cells could also be labeled differentially from either side of the plasma membrane.

  18. Dependence of the specific surface area of the nuclear fuel with the matrix oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Gomez, F.; Quinones, J.; Iglesias, E.; Rodriguez, N. [CIEMAT. Avda. Complutense 22, 28040-Madrid (Spain)

    2008-07-01

    This paper is focused on the study of the changes in the specific surface area measured using BET techniques. The objective is to obtain a relation between this parameter and the change in the matrix stoichiometry (i.e., oxidation increase). None of the actual models used for extrapolating the behaviour of the spent fuel matrix under repository conditions have included this dependence yet. In this work the specific surface area of different uranium oxide were measured using N{sub 2}(g) and Kr(g). The starting material was UO{sub 2+x}(s) with a size powder distribution lower than 20 {mu}m. The results included in this paper shown a strong dependence on specific surface area with the matrix stoichiometry, i.e., and increase of more than one order of magnitude (SUO{sub 2} = 6 m{sup 2}*g{sup -1} and SU{sub 3}O{sub 8} = 16.07 m{sup 2}*g{sup -1}). Furthermore, the particle size distribution measured as a function of the thermal treatment done shows changes on the powder size related to the changes observed in the uranium oxide stoichiometry. (authors)

  19. Motility assays using myosin attached to surfaces through specific binding to monoclonal antibodies.

    Science.gov (United States)

    Winkelmann, D A; Bourdieu, L; Kinose, F; Libchaber, A

    1995-04-01

    We have analyzed the dependence of actin filament movement on the mode of myosin attachment to surfaces. Monoclonal antibodies that bind to three distinct sites were used to tether myosin to nitrocellulose-coated glass. One antibody reacts with an epitope on the regulatory light chain located at the head-rod junction. The other two react with sites in the rod domain, one in the S2 region near the S2-LMM hinge, and the other at the C terminus of the myosin rod. These monoclonal antibodies were used to provide increasing flexibility in the mode of attachment. Fast skeletal muscle myosin monomers were bound to the surfaces through the specific interaction with these monoclonal antibodies and the sliding movement of fluorescently labeled actin filaments analyzed by video microscopy. Each of these antibodies produced stable, myosin-coated surfaces that supported uniform movement of actin over the course of several hours. Attachment of myosin through the anti-S2 and anti-LMM monoclonal antibodies yielded a maximum velocity of 10 microns/s at 30 degrees C, whereas attachment through anti-LC2 produced a lower velocity of 4-5 microns/s. Each antibody showed a characteristic minimum myosin density below which sliding movement was no longer supported and an exponential dependence of actin filament velocity on myosin surface density below Vmax. Maximum sliding velocity was achieved over a range of myosin surface densities. Thus, the specific mode of attachment can influence the characteristic velocity of actin filament movement and the surface density needed to support movement. These data are being used to analyze the dynamics of sliding filament assays and evaluate estimates of the average number of motor molecules per unit length of actin required to support movement.

  20. "Plug and play" full-dimensional ab initio potential energy and dipole moment surfaces and anharmonic vibrational analysis for CH4-H2O.

    Science.gov (United States)

    Qu, Chen; Conte, Riccardo; Houston, Paul L; Bowman, Joel M

    2015-03-28

    The potential energy surface of the methane-water dimer is represented as the sum of a new intrinsic two-body potential energy surface and pre-existing intramolecular potentials for the monomers. Different fits of the CH4-H2O intrinsic two-body energy are reported. All these fits are based on 30 467 ab initio interaction energies computed at CCSD(T)-F12b/haTZ (aug-cc-pVTZ for C and O, cc-pVTZ for H) level of theory. The benchmark fit is a full-dimensional, permutationally-invariant analytical representation with root-mean-square (rms) fitting error of 3.5 cm(-1). Two other computationally more efficient two-body potentials are also reported, albeit with larger rms fitting errors. Of these a compact permutationally invariant fit is shown to be the best one in combining precision and speed of evaluation. An intrinsic two-body dipole moment surface is also obtained, based on MP2/haTZ expectation values, with an rms fitting error of 0.002 au. As with the potential, this dipole moment surface is combined with existing monomer ones to obtain the full surface. The vibrational ground state of the dimer and dissociation energy, D0, are determined by diffusion Monte Carlo calculations, and MULTIMODE calculations are performed for the IR spectrum of the intramolecular modes. The relative accuracy of the different intrinsic two-body potentials is analyzed by comparing the energetics and the harmonic frequencies of the global minimum well, and the maximum impact parameter employed in a sample methane-water scattering calculation.

  1. Degradable polyester scaffolds with controlled surface chemistry combining minimal protein adsorption with specific bioactivation

    Science.gov (United States)

    Grafahrend, Dirk; Heffels, Karl-Heinz; Beer, Meike V.; Gasteier, Peter; Möller, Martin; Boehm, Gabriele; Dalton, Paul D.; Groll, Jürgen

    2011-01-01

    Advanced biomaterials and scaffolds for tissue engineering place high demands on materials and exceed the passive biocompatibility requirements previously considered acceptable for biomedical implants. Together with degradability, the activation of specific cell-material interactions and a three-dimensional environment that mimics the extracellular matrix are core challenges and prerequisites for the organization of living cells to functional tissue. Moreover, although bioactive signalling combined with minimization of non-specific protein adsorption is an advanced modification technique for flat surfaces, it is usually not accomplished for three-dimensional fibrous scaffolds used in tissue engineering. Here, we present a one-step preparation of fully synthetic, bioactive and degradable extracellular matrix-mimetic scaffolds by electrospinning, using poly(D,L-lactide-co-glycolide) as the matrix polymer. Addition of a functional, amphiphilic macromolecule based on star-shaped poly(ethylene oxide) transforms current biomedically used degradable polyesters into hydrophilic fibres, which causes the suppression of non-specific protein adsorption on the fibres’ surface. The subsequent covalent attachment of cell-adhesion-mediating peptides to the hydrophilic fibres promotes specific bioactivation and enables adhesion of cells through exclusive recognition of the immobilized binding motifs. This approach permits synthetic materials to directly control cell behaviour, for example, resembling the binding of cells to fibronectin immobilized on collagen fibres in the extracellular matrix of connective tissue.

  2. The illusion of specific capture: surface and solution studies of suboptimal oligonucleotide hybridization

    Science.gov (United States)

    2013-01-01

    Background Hybridization based assays and capture systems depend on the specificity of hybridization between a probe and its intended target. A common guideline in the construction of DNA microarrays, for instance, is that avoiding complementary stretches of more than 15 nucleic acids in a 50 or 60-mer probe will eliminate sequence specific cross-hybridization reactions. Here we present a study of the behavior of partially matched oligonucleotide pairs with complementary stretches starting well below this threshold complementarity length – in silico, in solution, and at the microarray surface. The modeled behavior of pairs of oligonucleotide probes and their targets suggests that even a complementary stretch of sequence 12 nt in length would give rise to specific cross-hybridization. We designed a set of binding partners to a 50-mer oligonucleotide containing complementary stretches from 6 nt to 21 nt in length. Results Solution melting experiments demonstrate that stable partial duplexes can form when only 12 bp of complementary sequence are present; surface hybridization experiments confirm that a signal close in magnitude to full-strength signal can be obtained from hybridization of a 12 bp duplex within a 50mer oligonucleotide. Conclusions Microarray and other molecular capture strategies that rely on a 15 nt lower complementarity bound for eliminating specific cross-hybridization may not be sufficiently conservative. PMID:23445545

  3. Large eddy simulation of LDL surface concentration in a subject specific human aorta.

    Science.gov (United States)

    Lantz, Jonas; Karlsson, Matts

    2012-02-02

    The development of atherosclerosis is correlated to the accumulation of lipids in the arterial wall, which, in turn, may be caused by the build-up of low-density lipoproteins (LDL) on the arterial surface. The goal of this study was to model blood flow within a subject specific human aorta, and to study how the LDL surface concentration changed during a cardiac cycle. With measured velocity profiles as boundary conditions, a scale-resolving technique (large eddy simulation, LES) was used to compute the pulsatile blood flow that was in the transitional regime. The relationship between wall shear stress (WSS) and LDL surface concentration was investigated, and it was found that the accumulation of LDL correlated well with WSS. In general, regions of low WSS corresponded to regions of increased LDL concentration and vice versa. The instantaneous LDL values changed significantly during a cardiac cycle; during systole the surface concentration was low due to increased convective fluid transport, while in diastole there was an increased accumulation of LDL on the surface. Therefore, the near-wall velocity was investigated at four representative locations, and it was concluded that in regions with disturbed flow the LDL concentration had significant temporal changes, indicating that LDL accumulation is sensitive to not only the WSS but also near-wall flow.

  4. Structural Investigations of Surfaces and Orientation-SpecificPhenomena in Nanocrystals and Their Assemblies

    Energy Technology Data Exchange (ETDEWEB)

    Aruguete, Deborah Michiko [Univ. of California, Berkeley, CA (United States)

    2006-01-01

    Studies of colloidal nanocrystals and their assemblies are presented. Two of these studies concern the atomic-level structural characterization of the surfaces, interfaces, and interiors present in II-VI semiconductor nanorods. The third study investigates the crystallographic arrangement of cobalt nanocrystals in self-assembled aggregates. Crystallographically-aligned assemblies of colloidal CdSe nanorods are examined with linearly-polarized Se-EXAFS spectroscopy, which probes bonding along different directions in the nanorod. This orientation-specific probe is used, because it is expected that the presence of specific surfaces in a nanorod might cause bond relaxations specific to different crystallographic directions. Se-Se distances are found to be contracted along the long axis of the nanorod, while Cd-Se distances display no angular dependence, which is different from the bulk. Ab-initio density functional theory calculations upon CdSe nanowires indicate that relaxations on the rod surfaces cause these changes. ZnS/CdS-CdSe core-shell nanorods are studied with Se, Zn, Cd, and S X-ray absorption spectroscopy (XAS). It is hypothesized that there are two major factors influencing the core and shell structures of the nanorods: the large surface area-to-volume ratio, and epitaxial strain. The presence of the surface may induce bond rearrangements or relaxations to minimize surface energy; epitaxial strain might cause the core and shell lattices to contract or expand to minimize strain energy. A marked contraction of Zn-S bonds is observed in the core-shell nanorods, indicating that surface relaxations may dominate the structure of the nanorod (strain might otherwise drive the Zn-S lattice to accommodate the larger CdS or CdSe lattices via bond expansion). EXAFS and X-ray diffraction (XRD) indicate that Cd-Se bond relaxations might be anisotropic, an expected phenomenon for a rod-shaped nanocrystal. Ordered self-assembled aggregates of cobalt nanocrystals are

  5. Vibrational relaxation and vibrational cooling in low temperature molecular crystals

    Science.gov (United States)

    Hill, Jeffrey R.; Chronister, Eric L.; Chang, Ta-Chau; Kim, Hackjin; Postlewaite, Jay C.; Dlott, Dana D.

    1988-01-01

    The processes of vibrational relaxation (VR) and vibrational cooling (VC) are investigated in low temperature crystals of complex molecules, specifically benzene, naphthalene, anthracene, and durene. In the VR process, a vibration is deexcited, while VC consists of many sequential and parallel VR steps which return the crystal to thermal equilibrium. A theoretical model is developed which relates the VR rate to the excess vibrational energy, the molecular structure, and the crystal structure. Specific relations are derived for the vibrational lifetime T1 in each of three regimes of excess vibrational energy. The regimes are the following: Low frequency regime I where VR occurs by emission of two phonons, intermediate frequency regime II where VR occurs by emission of one phonon and one vibration, and high frequency regime III where VR occurs by evolution into a dense bath of vibrational combinations. The VR rate in each regime depends on a particular multiphonon density of states and a few averaged anharmonic coefficients. The appropriate densities of states are calculated from spectroscopic data, and together with available VR data and new infrared and ps Raman data, the values of the anharmonic coefficients are determined for each material. The relationship between these parameters and the material properties is discussed. We then describe VC in a master equation formalism. The transition rate matrix for naphthalene is found using the empirically determined parameters of the above model, and the time dependent redistribution in each mode is calculated.

  6. The description of friction of silicon MEMS with surface roughness: virtues and limitations of a stochastic Prandtl–Tomlinson model and the simulation of vibration-induced friction reduction

    Directory of Open Access Journals (Sweden)

    W. Merlijn van Spengen

    2010-12-01

    Full Text Available We have replaced the periodic Prandtl–Tomlinson model with an atomic-scale friction model with a random roughness term describing the surface roughness of micro-electromechanical systems (MEMS devices with sliding surfaces. This new model is shown to exhibit the same features as previously reported experimental MEMS friction loop data. The correlation function of the surface roughness is shown to play a critical role in the modelling. It is experimentally obtained by probing the sidewall surfaces of a MEMS device flipped upright in on-chip hinges with an AFM (atomic force microscope. The addition of a modulation term to the model allows us to also simulate the effect of vibration-induced friction reduction (normal-force modulation, as a function of both vibration amplitude and frequency. The results obtained agree very well with measurement data reported previously.

  7. VIBRATION TESTING OF A SIXTEEN-STORIED BUILDING THAT HAS A PRECAST CONCRETE BOX STRUCTURE

    Directory of Open Access Journals (Sweden)

    Rumyantsev Anton Andreevich

    2012-10-01

    Full Text Available This article covers the problems of theoretical assessment of the seismic stability of a 16-storied building made of precast concrete box units by full-scale experimental testing through the employment of a powerful unbalance-type vibration machine. The authors provide the results of the experimental testing and scale them to assess the effects of an earthquake. The testing procedure that consists in the assessment of the seismic stability of buildings through employment of the vibration testing performed by a powerful vibration machine installed on the soil surface, have proven its high efficiency. As a result of the vibration testing, specific values of accelerations and shifts in terms of the building height and length were identified in lateral and longitudinal directions. The results of extrapolation of the seismic effect of the vibration testing onto the 9-grade seismic load scale have proven that the buildings of this type can be considered seismically stable.

  8. Evolution of the Specific Surface Area of Snow in a High Temperature Gradient Metamorphism

    Science.gov (United States)

    Wang, X.; Baker, I.

    2014-12-01

    The structural evolution of low-density snow under a high temperature gradient over a short period usually takes place in the surface layers during diurnal recrystallization or on a clear, cold night. To relate snow microstructures with their thermal properties, we combined X-ray computed microtomography (micro-CT) observations with numerical simulations. Different types of snow were tested over a large range of TGs (100 K m-1- 500 K m-1). The Specific Surface Area (SSA) was used to characterize the temperature gradient metamorphism (TGM). The magnitude of the temperature gradient and the initial snow type both influence the evolution of SSA. The SSA evolution under TGM was dominated by grain growth and the formation of complex surfaces. Fresh snow experienced a logarithmic decrease of SSA with time, a feature been observed previously by others [Calonne et al., 2014; Schneebeli and Sokratov, 2004; Taillandier et al., 2007]. However, for initial rounded and connected snow structures, the SSA will increase during TGM. Understanding the SSA increase is important in order to predict the enhanced uptake of chemical species by snow or increase in snow albedo. Calonne, N., F. Flin, C. Geindreau, B. Lesaffre, and S. Rolland du Roscoat (2014), Study of a temperature gradient metamorphism of snow from 3-D images: time evolution of microstructures, physical properties and their associated anisotropy, The Cryosphere Discussions, 8, 1407-1451, doi:10.5194/tcd-8-1407-2014. Schneebeli, M., and S. A. Sokratov (2004), Tomography of temperature gradient metamorphism of snow and associated changes in heat conductivity, Hydrological Processes, 18(18), 3655-3665, doi:10.1002/hyp.5800. Taillandier, A. S., F. Domine, W. R. Simpson, M. Sturm, and T. A. Douglas (2007), Rate of decrease of the specific surface area of dry snow: Isothermal and temperature gradient conditions, Journal of Geophysical Research: Earth Surface (2003-2012), 112(F3), doi: 10.1029/2006JF000514.

  9. Forced vibrations of a current-carrying nanowire in a longitudinal magnetic field accounting for both surface energy and size effects

    Science.gov (United States)

    Kiani, Keivan

    2014-09-01

    Forced vibrations of current-carrying nanowires in the presence of a longitudinal magnetic field are of interest. By considering the surface energy and size effects, the coupled equations of motion describing transverse motions of the nanostructure are derived. By employing Galerkin and Newmark-β approaches, the deflections of the nanowire subjected to transverse dynamic loads are evaluated. The effects of the magnetic field, electric current, pre-tension force, frequency of the applied load, surface and size effects on the maximum transverse displacements are discussed. The obtained results display that for the frequency of the applied load lower than the nanowire's fundamental frequency, by increasing the magnetic field or electric current, the maximum transverse displacements would increase. However, for exciting frequencies greater than that of the nanowire, maximum transverse displacements would increase or decrease with the magnetic field strength or electric current. Additionally, the pre-tension force results in decreasing of the maximum transverse displacements. Such a reduction is more apparent for higher values of the magnetic field strength and electric current. The present study would be useful in the design of the micro- and nano-electro-mechanical systems expected to be one of the most wanted technologies in the near future.

  10. On the vibrational behaviour of cyanide adsorbed at Pt(1 1 1) and Pt(1 0 0) surfaces in alkaline solutions

    Science.gov (United States)

    Huerta, F.; Montilla, F.; Morallón, E.; Vázquez, J. L.

    2006-03-01

    This communication deals with the vibrational behaviour of cyanide adlayers formed on Pt(1 1 1) and Pt(1 0 0) surfaces in the electrochemical environment. In situ FTIR spectroscopy can be employed to follow the potential dependence of the C-N stretching frequency in acidic electrolytes with quite a low uncertainty. Owing to the stability of the cyanide adlayer in alkaline solutions, experiments performed in NaOH medium are usually perturbed by the significant overlapping of the reference and the sample FTIR spectra. Deconvolution of the spectra was carried out assuming a Lorentz oscillator. The procedure allowed to confirm that two potential regions with different band centre frequency tuning coexist for Pt(1 1 1)-CN in perchloric acid medium. Conversely, in the alkaline electrolyte a single tuning rate for the band position was found for both surfaces studied. The lack of reorientation of the C-N molecular axis together with the occurrence of a certain screening effect of negatively charged hydroxyl anions on the electric field at the interface could be at the origin of the different behaviour displayed in both electrolytic media.

  11. Surface charge-specific interactions between polymer nanoparticles and ABC transporters in Caco-2 cells

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharjee, Sourav, E-mail: sourav.bhattacharjee@wur.nl [Wageningen University, Laboratory of Organic Chemistry (Netherlands); Opstal, Edward J. van; Alink, Gerrit M. [Wageningen University, Division of Toxicology (Netherlands); Marcelis, Antonius T. M.; Zuilhof, Han [Wageningen University, Laboratory of Organic Chemistry (Netherlands); Rietjens, Ivonne M. C. M. [Wageningen University, Division of Toxicology (Netherlands)

    2013-06-15

    The surface charge-dependent transport of polymeric nanoparticles (PNPs) across Caco-2 monolayers grown on transwell culture systems as an in vitro model for intestinal transport was tested. The transport of well-characterized, monodisperse, and fluorescent tri-block copolymer nanoparticles (TCNPs/size {approx}45 nm) and polystyrene nanoparticles (PSNPs/size {approx}50 nm), with different surface charges (positive and negative), was quantified. The positive PNPs showed a higher intracellular uptake and flux across the Caco-2 monolayers than the negative PNPs. Multidrug resistance/P-glycoprotein (MDR1/P-gp), a specific ATP-binding cassette (ABC) transporter, was found to play a major role in the cellular efflux of positive PNPs, whereas the multidrug resistance protein 1 took part in the efflux of negative PNPs from Caco-2 cells. The positive PNPs also caused an increased cellular uptake and apical to basolateral transport of the carcinogen PhIP across the Caco-2 monolayer. The flavonoid quercetin, which is known to interact with ABC transporters, promoted the intracellular uptake of different PNPs and interfered with the normal distribution patterns of PNPs in the transwell system. These results indicate that PNPs display surface charge-specific interactions with ABC transporters and can even affect the bioavailability of toxic food-borne compounds (like pro-carcinogens).

  12. Urban vibrations

    DEFF Research Database (Denmark)

    Morrison, Ann; Knudsen, L.; Andersen, Hans Jørgen

    2012-01-01

    In   this   paper   we   describe   a   field   study   conducted   with   a   wearable   vibration   belt   where   we   test   to   determine   the   vibration   intensity   sensitivity   ranges   on   a   large   diverse   group   of   participants   with   evenly   distributed  ages  and......   lab   studies   in   that   we   found   a   decreased   detection   rate   in   busy   environments.   Here   we   test   with   a   much   larger   sample   and   age   range,   and   contribute   with   the   first   vibration  sensitivity  testing  outside  the  lab  in  an  urban   public...

  13. Vibrational Fingerprints of Low-Lying Pt(n)P(2n) (n = 1-5) Cluster Structures from Global Optimization Based on Density Functional Theory Potential Energy Surfaces.

    Science.gov (United States)

    Jedidi, Abdesslem; Li, Rui; Fornasiero, Paolo; Cavallo, Luigi; Carbonniere, Philippe

    2015-12-03

    Vibrational fingerprints of small Pt(n)P(2n) (n = 1-5) clusters were computed from their low-lying structures located from a global exploration of their DFT potential energy surfaces with the GSAM code. Five DFT methods were assessed from the CCSD(T) wavenumbers of PtP2 species and CCSD relative energies of Pt2P4 structures. The eight first Pt(n)P(2n) isomers found are reported. The vibrational computations reveal (i) the absence of clear signatures made by overtone or combination bands due to very weak mechanical and electrical anharmonicities and (ii) some significant and recurrent vibrational fingerprints in correlation with the different PP bonding situations in the Pt(n)P(2n) structures.

  14. Determination of the specific surface area of snow using ozonation of 1,1-diphenylethylene.

    Science.gov (United States)

    Ray, Debajyoti; Kurková, Romana; Hovorková, Ivana; Klán, Petr

    2011-12-01

    We measured the kinetics of ozonation reaction of 1,1-diphenylethylene (DPE) in artificial snow, produced by shock freezing of DPE aqueous solutions sprayed into liquid nitrogen. It was demonstrated that most of the reactant molecules are in direct (productive) contact with gaseous ozone, thus the technique produces snow with organic molecules largely ejected to the surface of snow grains. The kinetic data were used to evaluate the snow specific surface area (∼70 cm(2) g(-1)). This number is a measure of the availability of the molecules on the surface for chemical reaction with gaseous species. The experimental results were consistent with the Langmuir-Hinshelwood type reaction mechanism. DPE represents environmentally relevant compounds such as alkenes which can react with atmospheric ozone, and are relatively abundant in natural snow. For typical atmospheric ozone concentrations in polar areas (20 ppbv), we estimated that half-life of DPE on the surface of snow grains is ∼5 days at submonolayer coverages and -15 °C.

  15. New Tools for the site-specific attachment of proteins to surface

    Energy Technology Data Exchange (ETDEWEB)

    Camarero, J A; Kwon, Y; Coleman, M A

    2005-06-17

    Protein microarrays in which proteins are immobilized to a solid surface are ideal reagents for high-throughput experiments that require very small amounts of analyte. Such protein microarrays ('protein chips') can be used very efficiently to analyze all kind of protein interactions en masse. Although a variety of methods are available for attaching proteins on solid surfaces. Most of them rely on non-specific adsorption methods or on the reaction of chemical groups within proteins (mainly, amino and carboxylic acid groups) with complementary reactive groups. In both cases the protein is attached to the surface in random orientations. The use of recombinant affinity tags addresses the orientation issue, however in most of the cases the interaction of the tags are reversible (e.g., glutathione S-transferase, maltose binding protein and poly-His) and, hence, are not stable over the course of subsequent assays or require large mediator proteins (e.g., biotin-avidin and antigen antibody). The key for the covalent attachment of a protein to a solid support with a total control over the orientation is to introduce two unique and mutually reactive groups on both the protein and the surface. The reaction between these two groups should be highly selective thus behaving like a molecular 'Velcro'.

  16. New Tools for the site-specific attachment of proteins to surface

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Y; Coleman, M A; Camarero, J A

    2006-06-27

    Protein microarrays in which proteins are immobilized to a solid surface are ideal reagents for high-throughput experiments that require very small amounts of analyte. Such protein microarrays (''protein chips'') can be used very efficiently to analyze all kind of protein interactions en masse. Although a variety of methods are available for attaching proteins on solid surfaces. Most of them rely on non-specific adsorption methods or on the reaction of chemical groups within proteins (mainly, amino and carboxylic acid groups) with complementary reactive groups. In both cases the protein is attached to the surface in random orientations. The use of recombinant affinity tags addresses the orientation issue, however in most of the cases the interaction of the tags are reversible (e.g., glutathione S-transferase, maltose binding protein and poly-His) and, hence, are not stable over the course of subsequent assays or require large mediator proteins (e.g., biotin-avidin and antigen antibody). The key for the covalent attachment of a protein to a solid support with a total control over the orientation is to introduce two unique and mutually reactive groups on both the protein and the surface. The reaction between these two groups should be highly selective thus behaving like a molecular ''velcro''.

  17. Functional Characterization of a Mucus-Specific LPXTG Surface Adhesin from Probiotic Lactobacillus rhamnosus GG ▿

    Science.gov (United States)

    von Ossowski, Ingemar; Satokari, Reetta; Reunanen, Justus; Lebeer, Sarah; De Keersmaecker, Sigrid C. J.; Vanderleyden, Jos; de Vos, Willem M.; Palva, Airi

    2011-01-01

    In spite of the wealth of clinical evidence supporting the health benefits of Lactobacillus rhamnosus GG in humans, there is still a lack of understanding of the molecular mechanisms behind its probiosis. Current knowledge suggests that the health-promoting effects of this probiotic strain might be partly dependent on its persistence in the intestine and adhesion to mucosal surfaces. Moreover, L. rhamnosus GG contains mucus-binding pili that might also explain the occupation of its ecological niche as a comparatively less stringent allochthonous intestine-dwelling bacterium. To uncover additional surface proteins involved in mucosal adhesion, we investigated the adherence properties of the only predicted protein (LGG_02337) in L. rhamnosus GG that exhibits homology with a known mucus-binding domain. We cloned a recombinant form of the gene for this putative mucus adhesin and established that the purified protein readily adheres to human intestinal mucus. We also showed that this mucus adhesin is visibly distributed throughout the cell surface and participates in the adhesive interaction between L. rhamnosus GG and mucus, although less prominently than the mucus-binding pili in this strain. Based on primary structural comparisons, we concluded that the current annotation of the LGG_02337 protein likely does not accurately reflect its predicted properties, and we propose that this mucus-specific adhesin be called the mucus-binding factor (MBF). Finally, we interpret our results to mean that L. rhamnosus GG MBF, as an active mucus-specific surface adhesin with a presumed ancillary involvement in pilus-mediated mucosal adhesion, plays a part in the adherent mechanisms during intestinal colonization by this probiotic. PMID:21602388

  18. Porphyromonas gingivalis Uses Specific Domain Rearrangements and Allelic Exchange to Generate Diversity in Surface Virulence Factors

    Science.gov (United States)

    Dashper, Stuart G.; Mitchell, Helen L.; Seers, Christine A.; Gladman, Simon L.; Seemann, Torsten; Bulach, Dieter M.; Chandry, P. Scott; Cross, Keith J.; Cleal, Steven M.; Reynolds, Eric C.

    2017-01-01

    Porphyromonas gingivalis is a keystone pathogen of chronic periodontitis. The virulence of P. gingivalis is reported to be strain related and there are currently a number of strain typing schemes based on variation in capsular polysaccharide, the major and minor fimbriae and adhesin domains of Lys-gingipain (Kgp), amongst other surface proteins. P. gingivalis can exchange chromosomal DNA between strains by natural competence and conjugation. The aim of this study was to determine the genetic variability of P. gingivalis strains sourced from international locations over a 25-year period and to determine if variability in surface virulence factors has a phylogenetic basis. Whole genome sequencing was performed on 13 strains and comparison made to 10 previously sequenced strains. A single nucleotide polymorphism-based phylogenetic analysis demonstrated a shallow tri-lobed phylogeny. There was a high level of reticulation in the phylogenetic network, demonstrating extensive horizontal gene transfer between the strains. Two highly conserved variants of the catalytic domain of the major virulence factor the Kgp proteinase (KgpcatI and KgpcatII) were found. There were three variants of the fourth Kgp C-terminal cleaved adhesin domain. Specific variants of the cell surface proteins FimA, FimCDE, MfaI, RagAB, Tpr, and PrtT were also identified. The occurrence of all these variants in the P. gingivalis strains formed a mosaic that was not related to the SNP-based phylogeny. In conclusion P. gingivalis uses domain rearrangements and genetic exchange to generate diversity in specific surface virulence factors. PMID:28184216

  19. Functional characterization of a mucus-specific LPXTG surface adhesin from probiotic Lactobacillus rhamnosus GG.

    Science.gov (United States)

    von Ossowski, Ingemar; Satokari, Reetta; Reunanen, Justus; Lebeer, Sarah; De Keersmaecker, Sigrid C J; Vanderleyden, Jos; de Vos, Willem M; Palva, Airi

    2011-07-01

    In spite of the wealth of clinical evidence supporting the health benefits of Lactobacillus rhamnosus GG in humans, there is still a lack of understanding of the molecular mechanisms behind its probiosis. Current knowledge suggests that the health-promoting effects of this probiotic strain might be partly dependent on its persistence in the intestine and adhesion to mucosal surfaces. Moreover, L. rhamnosus GG contains mucus-binding pili that might also explain the occupation of its ecological niche as a comparatively less stringent allochthonous intestine-dwelling bacterium. To uncover additional surface proteins involved in mucosal adhesion, we investigated the adherence properties of the only predicted protein (LGG_02337) in L. rhamnosus GG that exhibits homology with a known mucus-binding domain. We cloned a recombinant form of the gene for this putative mucus adhesin and established that the purified protein readily adheres to human intestinal mucus. We also showed that this mucus adhesin is visibly distributed throughout the cell surface and participates in the adhesive interaction between L. rhamnosus GG and mucus, although less prominently than the mucus-binding pili in this strain. Based on primary structural comparisons, we concluded that the current annotation of the LGG_02337 protein likely does not accurately reflect its predicted properties, and we propose that this mucus-specific adhesin be called the mucus-binding factor (MBF). Finally, we interpret our results to mean that L. rhamnosus GG MBF, as an active mucus-specific surface adhesin with a presumed ancillary involvement in pilus-mediated mucosal adhesion, plays a part in the adherent mechanisms during intestinal colonization by this probiotic.

  20. Pyrrole Hydrogenation over Rh(111) and Pt(111) Single-Crystal Surfaces and Hydrogenation Promotion Mediated by 1-Methylpyrrole: A Kinetic and Sum-Frequency Generation Vibrational Spectroscopy Study

    Energy Technology Data Exchange (ETDEWEB)

    Kliewer, Christopher J.; Bieri, Marco; Somorjai, Gabor A.

    2008-03-04

    Sum-frequency generation (SFG) surface vibrational spectroscopy and kinetic measurements using gas chromatography have been used to study the adsorption and hydrogenation of pyrrole over both Pt(111) and Rh(111) single-crystal surfaces at Torr pressures (3 Torr pyrrole, 30 Torr H{sub 2}) to form pyrrolidine and the minor product butylamine. Over Pt(111) at 298 K it was found that pyrrole adsorbs in an upright geometry cleaving the N-H bond to bind through the nitrogen evidenced by SFG data. Over Rh(111) at 298 K pyrrole adsorbs in a tilted geometry relative to the surface through the p-aromatic system. A pyrroline surface reaction intermediate, which was not detected in the gas phase, was seen by SFG during the hydrogenation over both surfaces. Significant enhancement of the reaction rate was achieved over both metal surfaces by adsorbing 1-methylpyrrole before reaction. SFG vibrational spectroscopic results indicate that reaction promotion is achieved by weakening the bonding between the N-containing products and the metal surface because of lateral interactions on the surface between 1-methylpyrrole and the reaction species, reducing the desorption energy of the products. It was found that the ring-opening product butylamine was a reaction poison over both surfaces, but this effect can be minimized by treating the catalyst surfaces with 1-methylpyrrole before reaction. The reaction rate was not enhanced with elevated temperatures, and SFG suggests desorption of pyrrole at elevated temperatures.

  1. Nitrogen-doped porous carbon with an ultrahigh specific surface area for superior performance supercapacitors

    Science.gov (United States)

    Long, Chao; Zhuang, Jianle; Xiao, Yong; Zheng, Mingtao; Hu, Hang; Dong, Hanwu; Lei, Bingfu; Zhang, Haoran; Liu, Yingliang

    2016-04-01

    Owing to its abundant nitrogen content, silk cocoon is a promising precursor for the synthesis of Nitrogen-doped porous carbon (N-PC). Using a simple staged KOH activation, the prepared sample displays particular nanostructure with ultrahigh specific surface area (3841 m2 g-1) and appropriate pore size, providing favorable pathways for transportation and penetration of electrolyte ions. Additionally, the doped nitrogen atoms ensure the samples with pseudocapacitive behavior. Those special characteristics endow N-PCs with high capacity, low resistance, and long-term stability, indicating a wonderful potential for application in energy-storage devices.

  2. Measurement of Specific Surface Area of Ceramisite Made from River Sediment

    Institute of Scientific and Technical Information of China (English)

    LIU Gui-yun; XI Dan-li

    2002-01-01

    Principle and method of measuring Specific Surface Area (SSA) of ceramisite made from dredged river sediment,sewage sludge and adherent materials are discussed.Brunauer-Fmmett- Teller Procedure tests SSA of the ceramisite. Influences of sewage sludge content,adherent content and sintering point on the SSA of ceramisite made of river sediment are also analyzed.Results show that with the right sewage sludge content,adherent content and sintering point, the ceramisite can have the highest SSA value and be widely used.

  3. Facile syntheses of 3-dimension graphene aerogel and nanowalls with high specific surface areas

    Science.gov (United States)

    Zhou, Lina; Yang, Zhongbo; Yang, Jun; Wu, Yonggang; Wei, Dongshan

    2017-06-01

    We propose facile synthesis methods to prepare two three-dimension (3D) multi-porous graphene structures including graphene aerogel and graphene nanowalls. The graphene aerogel was prepared via the hydrothermal reduction and tert-butanol freeze-drying. The graphene nanowalls were prepared by growing the obtained graphene aerogel via a plasma enhanced chemical vapor deposition (PECVD). High specific surface areas of these two structures up to 795 m2/g were obtained by BET analyses. The crystallized, multi-porous, and thermal stable features of these two 3D graphene structures were verified via the X-ray diffraction, SEM, Raman spectroscopy and thermal gravity analysis characterizations.

  4. Cation-induced monolayer collapse at lower surface pressure follows specific headgroup percolation

    Science.gov (United States)

    Das, Kaushik; Sah, Bijay Kumar; Kundu, Sarathi

    2017-02-01

    A Langmuir monolayer can be considered as a two-dimensional (2D) sheet at higher surface pressure which structurally deform with mechanical compression depending upon the elastic nature of the monolayer. The deformed structures formed after a certain elastic limit are called collapsed structures. To explore monolayer collapses at lower surface pressure and to see the effect of ions on such monolayer collapses, out-of-plane structures and in-plane morphologies of stearic acid Langmuir monolayers have been studied both at lower (≈6.8) and higher (≈9.5) subphase p H in the presence of M g2 +,C a2 +,Z n2 +,C d2 + , and B a2 + ions. At lower subphase p H and in the presence of all cations, the stearic acid monolayer remains as a monolayer before collapse, which generally takes place at higher surface pressure (πc>50 mN /m ). However, at higher subphase p H , structural changes of stearic acid monolayers occur at relatively lower surface pressure depending upon the specific dissolved ions. Among the same group elements of M g2 +,C a2 + , and B a2 + , only for B a2 + ions does monolayer to multilayer transition take place from a much lower surface pressure of the monolayer, remaining, however, as a monolayer for M g2 + and C a2 + ions. For another same group elements of Z n2 + and C d2 + ions, a less covered bilayer structure forms on top of the monolayer structure at lower surface pressure, which is evidenced from both x-ray reflectometry and atomic force microscopy. Fourier transform infrared spectroscopy confirms the presence of two coexisting conformations formed by the two different metal-headgroup coordinations and the monolayer to trilayer or multilayer transformation takes place when the coverage ratio of the two molecular conformations changes from the critical value (pc) of ≈0.66 . Such ion-specific monolayer collapses are correlated with the 2D lattice percolation model.

  5. Specific Features of Chip Making and Work-piece Surface Layer Formation in Machining Thermal Coatings

    Directory of Open Access Journals (Sweden)

    V. M. Yaroslavtsev

    2016-01-01

    Full Text Available A wide range of unique engineering structural and performance properties inherent in metallic composites characterizes wear- and erosion-resistant high-temperature coatings made by thermal spraying methods. This allows their use both in manufacturing processes to enhance the wear strength of products, which have to operate under the cyclic loading, high contact pressures, corrosion and high temperatures and in product renewal.Thermal coatings contribute to the qualitative improvement of the technical level of production and product restoration using the ceramic composite materials. However, the possibility to have a significantly increased product performance, reduce their factory labour hours and materials/output ratio in manufacturing and restoration is largely dependent on the degree of the surface layer quality of products at their finishing stage, which is usually provided by different kinds of machining.When machining the plasma-sprayed thermal coatings, a removing process of the cut-off layer material is determined by its distinctive features such as a layered structure, high internal stresses, low ductility material, high tendency to the surface layer strengthening and rehardening, porosity, high abrasive properties, etc. When coatings are machined these coating properties result in specific characteristics of chip formation and conditions for formation of the billet surface layer.The chip formation of plasma-sprayed coatings was studied at micro-velocities using an experimental tool-setting microscope-based setup, created in BMSTU. The setup allowed simultaneous recording both the individual stages (phases of the chip formation process and the operating force factors.It is found that formation of individual chip elements comes with the multiple micro-cracks that cause chipping-off the small particles of material. The emerging main crack in the cut-off layer of material leads to separation of the largest chip element. Then all the stages

  6. Vibrational spectroscopy

    Science.gov (United States)

    Umesh P. Agarwal; Rajai Atalla

    2010-01-01

    Vibrational spectroscopy is an important tool in modern chemistry. In the past two decades, thanks to significant improvements in instrumentation and the development of new interpretive tools, it has become increasingly important for studies of lignin. This chapter presents the three important instrumental methods-Raman spectroscopy, infrared (IR) spectroscopy, and...

  7. Vibrating minds

    CERN Document Server

    2009-01-01

    Ed Witten is one of the leading scientists in the field of string theory, the theory that describes elementary particles as vibrating strings. This week he leaves CERN after having spent a few months here on sabbatical. His wish is that the LHC will unveil supersymmetry.

  8. Surface mesh to voxel data registration for patient-specific anatomical modeling

    Science.gov (United States)

    de Oliveira, Júlia E. E.; Giessler, Paul; Keszei, András.; Herrler, Andreas; Deserno, Thomas M.

    2016-03-01

    Virtual Physiological Human (VPH) models are frequently used for training, planning, and performing medical procedures. The Regional Anaesthesia Simulator and Assistant (RASimAs) project has the goal of increasing the application and effectiveness of regional anesthesia (RA) by combining a simulator of ultrasound-guided and electrical nerve-stimulated RA procedures and a subject-specific assistance system through an integration of image processing, physiological models, subject-specific data, and virtual reality. Individualized models enrich the virtual training tools for learning and improving regional anaesthesia (RA) skills. Therefore, we suggest patient-specific VPH models that are composed by registering the general mesh-based models with patient voxel data-based recordings. Specifically, the pelvis region has been focused for the support of the femoral nerve block. The processing pipeline is composed of different freely available toolboxes such as MatLab, the open Simulation framework (SOFA), and MeshLab. The approach of Gilles is applied for mesh-to-voxel registration. Personalized VPH models include anatomical as well as mechanical properties of the tissues. Two commercial VPH models (Zygote and Anatomium) were used together with 34 MRI data sets. Results are presented for the skin surface and pelvic bones. Future work will extend the registration procedure to cope with all model tissue (i.e., skin, muscle, bone, vessel, nerve, fascia) in a one-step procedure and extrapolating the personalized models to body regions actually being out of the captured field of view.

  9. Polar interface and surface optical vibration spectra in multi-layer wurtzite quantum wires:transfer matrix method

    Institute of Scientific and Technical Information of China (English)

    Zhang Li

    2006-01-01

    The polar interface optical (IO) and surface optical (SO) phonon modes and the corresponding Frohlich electronphonon-interaction Hamiltonian in a freestanding multi-layer wurtzite cylindrical quantum wire (QWR) are derived and studied by employing the transfer matrix method in the dielectric continuum approximation and Loudon's uniaxial crystal model. A numerical calculation of a freestanding wurtzite GaN/AlN QWR is performed. The results reveal that for a relatively large azimuthal quantum number m or wave-number kz in the free z-direction, there exist two branches of IO phonon modes localized at the interface, and only one branch of SO mode localized at the surface in the system.The degenerating behaviours of the IO and SO phonon modes in the wurtzite QWR have also been clearly observed for a smallkz or m. The limiting frequency properties of the IO and SO modes for large kz and m have been explained reasonably from the mathematical and physical viewpoints. The calculations of electron-phonon coupling functions show that the high-frequency IO phonon branch and SO mode play a more important role in the electron-phonon interaction.

  10. On the protonation of oxo- and hydroxo-groups of the goethite (α-FeOOH) surface: A FTIR spectroscopic investigation of surface O H stretching vibrations

    Science.gov (United States)

    Boily, Jean-François; Felmy, Andrew R.

    2008-07-01

    The O-H stretching region of goethite particles evaporated at different levels of acidity was investigated by Attenuated Total Reflectance (ATR)-Fourier Transform InfraRed (FTIR) spectroscopy. Two-dimensional IR Correlation Spectroscopy was used to identify correlations between different sets of discrete surface OH stretches and a Multivariate Curve Resolution analysis was used to resolve the predominant spectral components. Two dominant groups of hydroxyls were identified on the basis of their differences in proton affinity. Group I hydroxyls appear as two 3698/3541 and 3660/3490 cm -1 band pairs. Group II hydroxyls are manifested through the 3648 and 3578 cm -1 bands at greater levels of surface proton loading. There is consequently no correlation between O-H stretching frequencies and proton affinity. Groups I and II were assigned to mostly singly- (-OH) and doubly- (μ-OH) coordinated hydroxyls, respectively. Stretches arising from triply-coordinated (μ 3-OH) are proposed to be embedded within the dominant O-H band of bulk goethite. The possibility that these sites contribute to Group I and II hydroxyls should, however, not be entirely dismissed without further investigations. A reexamination of Temperature Programmed Desorption (TPD)-FTIR data of one goethite sample evaporated from alkaline conditions [Boily J.-F., Szanyi J., Felmy A. R. (2006) A combined FTIR and TPD study on the bulk and surface dehydroxylation and decarbonation of synthetic goethite. Geochim. Cosmochim. Acta70, 3613-3624] provided further constraints to this band assignment by providing clues to the network of surface hydrogen bonds. Important cooperative effects between hydrogen-bonded surface hydroxyls are suggested to play a crucial role on the variations of the position and intensity of discrete O-H stretching bands as a function of protonation level and temperature.

  11. On the protonation of oxo- and hydroxo- groups of the goethite (α-FeOOH) surface: A FTIR spectroscopic investigation of surface O-H stretching vibrations.

    Energy Technology Data Exchange (ETDEWEB)

    Boily, Jean F; Felmy, Andrew R

    2008-06-01

    The O–H stretching region of goethite particles evaporated at different levels of acidity was investigated by Attenuated Total Reflectance (ATR)-Fourier Transform InfraRed (FTIR) spectroscopy. Two-dimensional IR Correlation Spectroscopy was used to identify correlations between different sets of discrete surface OH stretches and a Multivariate Curve Resolution analysis was used to resolve the predominant spectral components. Two dominant groups of hydroxyls were identified on the basis of their differences in proton affinity. Group I hydroxyls appear as two 3698/3541 and 3660/3490 cm-1 band pairs. Group II hydroxyls are manifested through the 3648 and 3578 cm-1 bands at greater levels of surface proton loading. There is consequently no correlation between O–H stretching frequencies and proton affinity. Groups I and II were assigned to mostly singly- (–OH) and doubly- (μ-OH) coordinated hydroxyls, respectively. Stretches arising from triply-coordinated (μ3-OH) are proposed to be embedded within the dominant O–H band of bulk goethite. The possibility that these sites contribute to Group I and II hydroxyls should, however, not be entirely dismissed without further investigations. A reexamination of Temperature Programmed Desorption (TPD)-FTIR data of one goethite sample evaporated from alkaline conditions [Boily J.-F., Szanyi J., Felmy A. R. (2006) A combined FTIR and TPD study on the bulk and surface dehydroxylation and decarbonation of synthetic goethite. Geochim. Cosmochim. Acta70, 3613–3624] provided further constraints to this band assignment by providing clues to the network of surface hydrogen bonds. Important cooperative effects between hydrogen-bonded surface hydroxyls are suggested to play a crucial role on the variations of the position and intensity of discrete O–H stretching bands as a function of protonation level and temperature.

  12. The brain-specific Beta4 subunit downregulates BK channel cell surface expression.

    Science.gov (United States)

    Shruti, Sonal; Urban-Ciecko, Joanna; Fitzpatrick, James A; Brenner, Robert; Bruchez, Marcel P; Barth, Alison L

    2012-01-01

    The large-conductance K(+) channel (BK channel) can control neural excitability, and enhanced channel currents facilitate high firing rates in cortical neurons. The brain-specific auxiliary subunit β4 alters channel Ca(++)- and voltage-sensitivity, and β4 knock-out animals exhibit spontaneous seizures. Here we investigate β4's effect on BK channel trafficking to the plasma membrane. Using a novel genetic tag to track the cellular location of the pore-forming BKα subunit in living cells, we find that β4 expression profoundly reduces surface localization of BK channels via a C-terminal ER retention sequence. In hippocampal CA3 neurons from C57BL/6 mice with endogenously high β4 expression, whole-cell BK channel currents display none of the characteristic properties of BKα+β4 channels observed in heterologous cells. Finally, β4 knock-out animals exhibit a 2.5-fold increase in whole-cell BK channel current, indicating that β4 also regulates current magnitude in vivo. Thus, we propose that a major function of the brain-specific β4 subunit in CA3 neurons is control of surface trafficking.

  13. The brain-specific Beta4 subunit downregulates BK channel cell surface expression.

    Directory of Open Access Journals (Sweden)

    Sonal Shruti

    Full Text Available The large-conductance K(+ channel (BK channel can control neural excitability, and enhanced channel currents facilitate high firing rates in cortical neurons. The brain-specific auxiliary subunit β4 alters channel Ca(++- and voltage-sensitivity, and β4 knock-out animals exhibit spontaneous seizures. Here we investigate β4's effect on BK channel trafficking to the plasma membrane. Using a novel genetic tag to track the cellular location of the pore-forming BKα subunit in living cells, we find that β4 expression profoundly reduces surface localization of BK channels via a C-terminal ER retention sequence. In hippocampal CA3 neurons from C57BL/6 mice with endogenously high β4 expression, whole-cell BK channel currents display none of the characteristic properties of BKα+β4 channels observed in heterologous cells. Finally, β4 knock-out animals exhibit a 2.5-fold increase in whole-cell BK channel current, indicating that β4 also regulates current magnitude in vivo. Thus, we propose that a major function of the brain-specific β4 subunit in CA3 neurons is control of surface trafficking.

  14. The specificity of targeted vaccines for APC surface molecules influences the immune response phenotype.

    Directory of Open Access Journals (Sweden)

    Gunnveig Grødeland

    Full Text Available Different diseases require different immune responses for efficient protection. Thus, prophylactic vaccines should prime the immune system for the particular type of response needed for protection against a given infectious agent. We have here tested fusion DNA vaccines which encode proteins that bivalently target influenza hemagglutinins (HA to different surface molecules on antigen presenting cells (APC. We demonstrate that targeting to MHC class II molecules predominantly induced an antibody/Th2 response, whereas targeting to CCR1/3/5 predominantly induced a CD8(+/Th1 T cell response. With respect to antibodies, the polarizing effect was even more pronounced upon intramuscular (i.m delivery as compared to intradermal (i.d. vaccination. Despite these differences in induced immune responses, both vaccines protected against a viral challenge with influenza H1N1. Substitution of HA with ovalbumin (OVA demonstrated that polarization of immune responses, as a consequence of APC targeting specificity, could be extended to other antigens. Taken together, the results demonstrate that vaccination can be tailor-made to induce a particular phenotype of adaptive immune responses by specifically targeting different surface molecules on APCs.

  15. Characteristics of PAHs adsorbed on street dust and the correlation with specific surface area and TOC.

    Science.gov (United States)

    Wang, Chengkun; Li, Yingxia; Liu, Jingling; Xiang, Li; Shi, Jianghong; Yang, Zhifeng

    2010-10-01

    Street dust was collected from five roads with different traffic volumes in the metropolitan area of Beijing and separated into five size fractions. Concentrations of polycyclic aromatic hydrocarbons (PAHs) adsorbed on street dust in different size ranges and their correlation with specific surface area and total organic carbon (TOC) were investigated. Results show that the concentration of 16-PAHs of sieved samples ranges from 0.27 to 1.30 mg/kg for all the sampling sites. Particles smaller than 40 mum in diameter have the highest 16-PAHs concentration among all of the size ranges for street dust from the four sampling sites with vehicles running on. PAHs with three or four rings account for 68% of the overall 16-PAHs on average. Remarkable positive correlation exists between 16-PAHs concentration and specific surface area with R(2) values from 0.7 to 0.96 for the four sampling sites with vehicles running on. The relationship between the concentration of 16-PAHs and TOC is less clear.

  16. Non-conventional halide oxidation pathways : oxidation by imidazole triplet and surface specific oxidation by ozone

    Science.gov (United States)

    Ammann, Markus; Corral-Arroyo, Pablo; Aellig, Raphael; Orlando, Fabrizio; Lee, Ming-Tao; Artiglia, Luca

    2016-04-01

    Oxidation of halide ions (chloride, bromide, iodide) are the starting point of halogen release mechanisms out of sea water, marine aerosol or other halide containing continental aerosols. Slow oxidation of chloride and bromide by ozone in the bulk aqueous phase is of limited relevance. Faster surface specific oxidation has been suggested based on heterogeneous kinetics experiments. We provide first insight into very efficient bromide oxidation by ozone at the aqueous solution - air interface by surface sensitive X-ray photoelectron spectroscopy indicating significant build-up of an oxidized intermediate at the surface within millisecond time scales. The second source of oxidants in the condensed we have considered is the absorption of light by triplet forming photosensitizers at wavelengths longer than needed for direct photolysis and radical formation. We have performed coated wall flow tube experiments with mixtures of citric acid (CA) and imidazole-2-carboxaldehyde (IC) to represent secondary organic material rich marine aerosol. The halide ions bromide and iodide have been observed to act as efficient electron donors leading to their oxidation, HO2 formation and finally release of molecular halogen compounds. The photosensitization of imidazole-2-carboxaldehyde (IC) involves a well-known mechanism where the triplet excited state of IC is reduced by citric acid to a reduced ketyl radical that reacts with halide ions. A competition kinetics approach has been used to evaluate the rate limiting steps and to assess the significance of this source of halogens to the gas phase.

  17. Ligand-specific regulation of the extracellular surface of a G-protein-coupled receptor

    Energy Technology Data Exchange (ETDEWEB)

    Bokoch, Michael P.; Zou, Yaozhong; Rasmussen, Søren G.F.; Liu, Corey W.; Nygaard, Rie; Rosenbaum, Daniel M.; Fung, Juan José; Choi, Hee-Jung; Thian, Foon Sun; Kobilka, Tong Sun; Puglisi, Joseph D.; Weis, William I.; Pardo, Leonardo; Prosser, R. Scott; Mueller, Luciano; Kobilka, Brian K. (Stanford-MED); (Toronto); (BMS); (UAB, Spain)

    2010-01-14

    G-protein-coupled receptors (GPCRs) are seven-transmembrane proteins that mediate most cellular responses to hormones and neurotransmitters. They are the largest group of therapeutic targets for a broad spectrum of diseases. Recent crystal structures of GPCRs have revealed structural conservation extending from the orthosteric ligand-binding site in the transmembrane core to the cytoplasmic G-protein-coupling domains. In contrast, the extracellular surface (ECS) of GPCRs is remarkably diverse and is therefore an ideal target for the discovery of subtype-selective drugs. However, little is known about the functional role of the ECS in receptor activation, or about conformational coupling of this surface to the native ligand-binding pocket. Here we use NMR spectroscopy to investigate ligand-specific conformational changes around a central structural feature in the ECS of the {beta}{sub 2} adrenergic receptor: a salt bridge linking extracellular loops 2 and 3. Small-molecule drugs that bind within the transmembrane core and exhibit different efficacies towards G-protein activation (agonist, neutral antagonist and inverse agonist) also stabilize distinct conformations of the ECS. We thereby demonstrate conformational coupling between the ECS and the orthosteric binding site, showing that drugs targeting this diverse surface could function as allosteric modulators with high subtype selectivity. Moreover, these studies provide a new insight into the dynamic behaviour of GPCRs not addressable by static, inactive-state crystal structures.

  18. Standard Specification for Steel Blades Used with the Photovoltaic Module Surface Cut Test

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2009-01-01

    1.1 This specification specifies the recommended physical characteristics of the steel blades required for the surface cut test described in ANSI/UL 1703 (Section 24) and IEC 61730-2 (Paragraph 10.3). 1.2 ANSI/UL 1703 and IEC 61730-2 are standards for photovoltaic module safety testing. 1.3 This standard provides additional fabrication details for the surface cut test blades that are not provided in ANSI/UL 1703 or IEC 61730-2. Surface cut test blades that have out-of-tolerance corner radii or burrs are known to cause erroneous test results, either passes or failures. 1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.5 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

  19. Experimental verification of the identity of variant-specific surface proteins in Giardia lamblia trophozoites.

    Science.gov (United States)

    Li, Wei; Saraiya, Ashesh A; Wang, Ching C

    2013-05-21

    The cell membrane of a Giardia lamblia trophozoite is covered with a single species of variant-specific surface protein (VSP) that is replaced by another VSP every 6 to 13 generations of cell growth, possibly for an evasion of host immunity. Experimentally, only six VSP species have been verified to localize to the cell membrane thus far. By assuming that VSP contains multiple CXXC motifs, 219 vsp genes were annotated in GiardiaDB of the WB isolate. By further assuming that VSP possesses both CXXC motifs and a CRGKA tail at the C terminus, Adam et al. (BMC Genomics 11:424, 2010) identified a total of 303 potential vsp genes in Giardia WB. The discrepancies between these two assumed VSP identities have caused some confusion. Here, we used experimental approaches to further verify what is required of the structures of a VSP to localize to the surface of cell membrane. The data led to the following conclusions. (i) The C-terminal CRGKA sequence is not essential for localizing VSPs to the cell membrane. (ii) A "motif 1" of 45 residues, consisting of two CXXCs separated by 12 to 15 amino acid residues, located close to the C terminus and a hydrophobic "motif 2" of 38 residues at the C terminus are both essential and sufficient for localizing the protein to the cell membrane. (ii) An N-terminal sequence upstream from motif 1 is not required for targeting VSPs to the cell membrane. By these criteria, we are able to identify 73 open reading frames as the putative vsp genes in Giardia. IMPORTANCE The intestinal pathogen Giardia lamblia expresses only one variant-specific surface protein (VSP) on the cell membrane surface at a given time, but it changes spontaneously every 6 to 13 generations of growth, presumably for evading the host immunity. Only 6 VSPs have been empirically shown to localize to the cell membrane surface thus far. Here, we used mutations of VSPs and methods of identifying their locations in Giardia cells and found that a "motif 1" of 45 residues

  20. Specific binding of avidin to biotin containing lipid lamella surfaces studied with monolayers and liposomes.

    Science.gov (United States)

    Liu, Z; Qin, H; Xiao, C; Wen, C; Wang, S; Sui, S F

    1995-01-01

    The interaction of avidin (from egg white) with phospholipid (monolayer and bilayer) model membranes containing biotin-conjugated phospholipids has been studied. In the first part, using surface sensitive techniques (ellipsometry and surface plasmon resonance) we demonstrated that the nonspecific adsorption of avidin to phospholipid lamella could be abolished by adding an amount of Ca2+, Mg2+ or Ba2+ that led to an electrostatic interaction. The specific binding of avidin to lipid mixtures containing biotin-conjugated phospholipids was obviously composition dependent. The ratio 1:12 of a B-DPPE/DPPE mixture was found to be the optimum molar ratio. When we compared the results from the surface sensitive techniques with those from the electron micrographs of a two dimensional crystal of avidin (obtained in our laboratory), the optimum ratio was found to be determined by the effect of lateral steric hindrance. In the second part, we observed the pattern of the layers of fluorescently labeled phospholipid and adsorbed proteins with a home-made micro fluorescence film balance. The fluorescence images showed that avidin was preferentially bound to the receptors that were in the fluid domains. Further, with a sensitive fluorescence assay method, the effect of the phase behavior of liposomes on the specific binding of avidin was measured. This showed that avidin interacted with biotinlipid more weakly in the gel state liposome than in the liquid state liposome. The major conclusion was that the binding of avidin to a membrane bound model receptor was significantly restricted by two factors: one was the lateral steric hindrance and the other was the fluidity of the model membrane.

  1. A new set of potential energy surfaces for HCO: Influence of Renner-Teller coupling on the bound and resonance vibrational states

    Science.gov (United States)

    Ndengué, Steve Alexandre; Dawes, Richard; Guo, Hua

    2016-06-01

    It is commonly understood that the Renner-Teller effect can strongly influence the spectroscopy of molecules through coupling of electronic states. Here we investigate the vibrational bound states and low-lying resonances of the formyl radical treating the Renner-Teller coupled X˜ 2A' and A˜ 2A″ states using the MultiConfiguration Time Dependent Hartree (MCTDH) method. The calculations were performed using the improved relaxation method for the bound states and a recently published extension to compute resonances. A new set of accurate global potential energy surfaces were computed at the explicitly correlated multireference configuration interaction (MRCI-F12) level and yielded remarkably close agreement with experiment in this application and thus enable future studies including photodissociation and collisional dynamics. The results show the necessity of including the large contribution from a Davidson correction in the electronic structure calculations in order to appreciate the relatively small effect of the Renner-Teller coupling on the states considered here.

  2. Vibrational spectroscopy at electrified interfaces

    CERN Document Server

    Wieckowski, Andrzej; Braunschweig, Björn

    2013-01-01

    Reviews the latest theory, techniques, and applications Surface vibrational spectroscopy techniques probe the structure and composition of interfaces at the molecular level. Their versatility, coupled with their non-destructive nature, enables in-situ measurements of operating devices and the monitoring of interface-controlled processes under reactive conditions. Vibrational Spectroscopy at Electrified Interfaces explores new and emerging applications of Raman, infrared, and non-linear optical spectroscopy for the study of charged interfaces. The book draws from hu

  3. Multi-Plane High Speed Balancing Techniques and the Use of a High Specific Stiffness Ti-Borsic Material for Vibration Control.

    Science.gov (United States)

    1980-02-01

    cruise * missile rotor through four critical speeds, thereby reducing unbalance related vibration. A rotordynamics analysis of the LP rotor was...Design included structural and rotordynamics analysis (undamped critical speed analysis and unbalance response analysis) of a metal matrix LP shaft for the... Rotordynamics analyses resulted in predicted rotor critical speeds at *approximately 5,000, 8,000, 14,000 and 30,000 RPM. Based on calculated moade

  4. Characterization of the molecular structure and mechanical properties of polymer surfaces and protein/polymer interfaces by sum frequency generation vibrational spectroscopy and atomic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Koffas, Telly Stelianos [Univ. of California, Berkeley, CA (United States)

    2004-01-01

    Sum frequency generation (SFG) vibrational spectroscopy, atomic force microscopy (AFM), and other complementary surface-sensitive techniques have been used to study the surface molecular structure and surface mechanical behavior of biologically-relevant polymer systems. SFG and AFM have emerged as powerful analytical tools to deduce structure/property relationships, in situ, for polymers at air, liquid and solid interfaces. The experiments described in this dissertation have been performed to understand how polymer surface properties are linked to polymer bulk composition, substrate hydrophobicity, changes in the ambient environment (e.g., humidity and temperature), or the adsorption of macromolecules. The correlation of spectroscopic and mechanical data by SFG and AFM can become a powerful methodology to study and engineer materials with tailored surface properties. The overarching theme of this research is the interrogation of systems of increasing structural complexity, which allows us to extend conclusions made on simpler model systems. We begin by systematically describing the surface molecular composition and mechanical properties of polymers, copolymers, and blends having simple linear architectures. Subsequent chapters focus on networked hydrogel materials used as soft contact lenses and the adsorption of protein and surfactant at the polymer/liquid interface. The power of SFG is immediately demonstrated in experiments which identify the chemical parameters that influence the molecular composition and ordering of a polymer chain's side groups at the polymer/air and polymer/liquid interfaces. In general, side groups with increasingly greater hydrophobic character will be more surface active in air. Larger side groups impose steric restrictions, thus they will tend to be more randomly ordered than smaller hydrophobic groups. If exposed to a hydrophilic environment, such as water, the polymer chain will attempt to orient more of its hydrophilic groups to

  5. Characterization of the molecular structure and mechanical properties of polymer surfaces and protein/polymer interfaces by sum frequency generation vibrational spectroscopy and atomic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Koffas, Telly Stelianos

    2004-05-15

    Sum frequency generation (SFG) vibrational spectroscopy, atomic force microscopy (AFM), and other complementary surface-sensitive techniques have been used to study the surface molecular structure and surface mechanical behavior of biologically-relevant polymer systems. SFG and AFM have emerged as powerful analytical tools to deduce structure/property relationships, in situ, for polymers at air, liquid and solid interfaces. The experiments described in this dissertation have been performed to understand how polymer surface properties are linked to polymer bulk composition, substrate hydrophobicity, changes in the ambient environment (e.g., humidity and temperature), or the adsorption of macromolecules. The correlation of spectroscopic and mechanical data by SFG and AFM can become a powerful methodology to study and engineer materials with tailored surface properties. The overarching theme of this research is the interrogation of systems of increasing structural complexity, which allows us to extend conclusions made on simpler model systems. We begin by systematically describing the surface molecular composition and mechanical properties of polymers, copolymers, and blends having simple linear architectures. Subsequent chapters focus on networked hydrogel materials used as soft contact lenses and the adsorption of protein and surfactant at the polymer/liquid interface. The power of SFG is immediately demonstrated in experiments which identify the chemical parameters that influence the molecular composition and ordering of a polymer chain's side groups at the polymer/air and polymer/liquid interfaces. In general, side groups with increasingly greater hydrophobic character will be more surface active in air. Larger side groups impose steric restrictions, thus they will tend to be more randomly ordered than smaller hydrophobic groups. If exposed to a hydrophilic environment, such as water, the polymer chain will attempt to orient more of its hydrophilic groups to

  6. Method and apparatus for vibrating a substrate during material formation

    Science.gov (United States)

    Bailey, Jeffrey A [Richland, WA; Roger, Johnson N [Richland, WA; John, Munley T [Benton City, WA; Walter, Park R [Benton City, WA

    2008-10-21

    A method and apparatus for affecting the properties of a material include vibrating the material during its formation (i.e., "surface sifting"). The method includes the steps of providing a material formation device and applying a plurality of vibrations to the material during formation, which vibrations are oscillations having dissimilar, non-harmonic frequencies and at least two different directions. The apparatus includes a plurality of vibration sources that impart vibrations to the material.

  7. Vibration Induced Microfluidic Atomization

    Science.gov (United States)

    Yeo, Leslie; Qi, Aisha; Friend, James

    2008-11-01

    We demonstrate rapid generation of micron aerosol droplets in a microfluidic device in which a fluid drop is exposed to surface vibration as it sits atop a piezoelectric substrate. Little, however, is understood about the processes by which these droplets form due to the complex hydrodynamic processes that occur across widely varying length and time scales. Through experiments, scaling theory and numerical modelling, we elucidate the interfacial destabilization mechanisms that lead to droplet formation. Droplets form due to the axisymmetric break-up of cylindrical liquid jets ejected as a consequence of interfacial destabilization. Their 10 μm size correlates with the jet radius and the instability wavelength, both determined from a viscous-capillary dominant force balance and confirmed through a numerical solution. With the exception of drops that spread into thin films with thicknesses on the order of the boundary layer dimension, the free surface is always observed to vibrate at the capillary-viscous resonance frequency despite the surface vibration frequency being several orders larger. This is contrary to common assumptions used in deriving subharmonic models resulting in a Mathieu equation, which has commonly led to spurious predictions in the droplet size.

  8. HadISDH: an updated land surface specific humidity product for climate monitoring

    Directory of Open Access Journals (Sweden)

    K. M. Willett

    2012-10-01

    Full Text Available Presented herein is HadISDH: an annually-updated near-global land-surface specific humidity product providing monthly means from 1973 onwards over large scale grids. HadISDH is an update to the land component of HadCRUH utilising the global high resolution land surface station product HadISD as a basis. HadISD, in turn uses an updated version of NOAA's integrated surface database. Intensive automated quality control has been undertaken at the synoptic level, as part of HadISD processing. The data have been subsequently run through the pairwise homogenisation algorithm developed for NCDC's GHCN Monthly temperature product. Uncertainty estimates including station uncertainty and sampling uncertainty are provided at the gridbox spatial scale and monthly time scale.

    HadISDH is in good agreement with existing land surface humidity products in periods of overlap. Widespread moistening is shown over the 1973–2011 period. The largest moistening signals are over the tropics with drying over the subtropics, supporting other evidence of an intensified hydrological cycle over recent years. Moistening is detectable with high (95% confidence over large-scale averages for the globe, Northern Hemisphere and tropics with trends of 0.095 (0.086 to 0.105 g kg−1 per decade, 0.091 (0.08 to 0.103 g kg−1 per decade and 0.147 (0.133 to 0.162 g kg−1 per decade, respectively. No change (0.008 (−0.011 to 0.028 g kg−1 per decade is detectable in the Southern Hemisphere. When globally averaged, 1998 was the moistest year since records began in 1973, closely followed by 2010, two strong El Niño years.

  9. Biomaterial design for specific cellular interactions: Role of surface functionalization and geometric features

    Science.gov (United States)

    Kolhar, Poornima

    The areas of drug delivery and tissue engineering have experienced extraordinary growth in recent years with the application of engineering principles and their potential to support and improve the field of medicine. The tremendous progress in nanotechnology and biotechnology has lead to this explosion of research and development in biomedical applications. Biomaterials can now be engineered at a nanoscale and their specific interactions with the biological tissues can be modulated. Various design parameters are being established and researched for design of drug-delivery carriers and scaffolds to be implanted into humans. Nanoparticles made from versatile biomaterial can deliver both small-molecule drugs and various classes of bio-macromolecules, such as proteins and oligonucleotides. Similarly in the field of tissue engineering, current approaches emphasize nanoscale control of cell behavior by mimicking the natural extracellular matrix (ECM) unlike, traditional scaffolds. Drug delivery and tissue engineering are closely connected fields and both of these applications require materials with exceptional physical, chemical, biological, and biomechanical properties to provide superior therapy. In the current study the surface functionalization and the geometric features of the biomaterials has been explored. In particular, a synthetic surface for culture of human embryonic stem cells has been developed, demonstrating the importance of surface functionalization in maintaining the pluripotency of hESCs. In the second study, the geometric features of the drug delivery carriers are investigated and the polymeric nanoneedles mediated cellular permeabilization and direct cytoplasmic delivery is reported. In the third study, the combined effect of surface functionalization and geometric modification of carriers for vascular targeting is enunciated. These studies illustrate how the biomaterials can be designed to achieve various cellular behaviors and control the

  10. Atom-specific look at the surface chemical bond using x-ray emission spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Nilsson, A.; Wassdahl, N.; Weinelt, M. [Uppsala Univ. (Sweden)] [and others

    1997-04-01

    CO and N{sub 2} adsorbed on the late transition metals have become prototype systems regarding the general understanding of molecular adsorption. It is in general assumed that the bonding of molecules to transition metals can be explained in terms of the interaction of the frontier HOMO and LUMO molecular orbitals with the d-orbitals. In such a picture the other molecular orbitals should remain essentially the same as in the free molecule. For the adsorption of the isoelectronic molecules CO and N{sub 2} this has led to the so called Blyholder model i.e., a synergetic {sigma} (HOMO) donor and {pi} (LUMO) backdonation bond. The authors results at the ALS show that such a picture is oversimplified. The direct observation and identification of the states related to the surface chemical bond is an experimental challenge. For noble and transition metal surfaces, the adsorption induced states overlap with the metal d valence band. Their signature is therefore often obscured by bulk substrate states. This complication has made it difficult for techniques such as photoemission and inverse photoemission to provide reliable information on the energy of chemisorption induced states and has left questions unanswered regarding the validity of the frontier orbitals concept. Here the authors show how x-ray emission spectroscopy (XES), in spite of its inherent bulk sensitivity, can be used to investigate adsorbed molecules. Due to the localization of the core-excited intermediate state, XE spectroscopy allows an atomic specific separation of the valence electronic states. Thus the molecular contributions to the surface measurements make it possible to determine the symmetry of the molecular states, i.e., the separation of {pi} and {sigma} type states. In all the authors can obtain an atomic view of the electronic states involved in the formation of the chemical bond to the surface.

  11. Production of vibrationally excited hydrogen molecules by atom recombination on Cu and W materials.

    Science.gov (United States)

    Markelj, Sabina; Čadež, Iztok

    2011-03-28

    We have measured vibrational population of H(2) and D(2) molecules produced by atom (H or D) recombination on tungsten and copper material. The vibrational spectroscopy, based on the properties of dissociative electron attachment to hydrogen molecule, was used. The vibrationally excited molecules were produced by atom recombination in a cell where the studied sample is exposed to hydrogen atoms, from hot tungsten filament. Vibrational populations were obtained for the studied materials, which can be well described by the Boltzmann distribution, with specific vibrational temperatures for each material. The experimentally obtained vibrational populations for copper approximately agree with the theoretical predictions, whereas the experimentally obtained vibrational temperature for tungsten is higher and thus showing a considerable overpopulation of highly excited vibrational states than predicted. We propose that the origin of this higher excitation is related to the existence of high hydrogen surface coverage on tungsten, where hydrogen is occupying binding sites with different desorption energies. In order to obtain an insight into the recombination mechanism with more than one binding site per unit cell, a Monte Carlo simulation was performed, where it was assumed that the main production of molecules proceeds through the hot-atom recombination with an adsorbed atom. The results show that the recombination proceeds mainly through the weak binding sites, once they are occupied.

  12. The responses to surface wettability gradients induced by chitosan nanofilms on microtextured titanium mediated by specific integrin receptors

    Science.gov (United States)

    Park, Jung Hwa; Wasilewski, Christine E.; Almodovar, Noelia; Olivares-Navarrete, Rene; Boyan, Barbara D.; Tannenbaum, Rina; Schwartz, Zvi

    2013-01-01

    Microtexture and chemistry of implant surfaces are important variables for modulating cellular responses. Surface chemistry and wettability are connected directly. While each of these surface properties can influence cell response, it is difficult to decouple their specific contributions. To address this problem, the aims of this study were to develop a surface wettability gradient with a specific chemistry without altering micron scale roughness and to investigate the role of surface wettability on osteoblast response. Microtextured sandblasted/acid-etched (SLA, Sa = 3.1 μm) titanium disks were treated with oxygen plasma to increase reactive oxygen density on the surface. At 0, 2, 6, 10, and 24 h after removing them from the plasma, the surfaces were coated with chitosan for 30 min, rinsed and dried. Modified SLA surfaces are denoted as SLA/h in air prior to coating. Surface characterization demonstrated that this process yielded differing wettability (SLA0 < SLA2 < SLA10 < SLA24) without modifying the micron scale features of the surface. Cell number was reduced in a wettability-dependent manner, except for the most water-wettable surface, SLA24. There was no difference in alkaline phosphatase activity with differing wettability. Increased wettability yielded increased osteocalcin and osteoprotegerin production, except on the SLA24 surfaces. mRNA for integrins α1, α2, α5, β1, and β3 was sensitive to surface wettability. However, surface wettability did not affect mRNA levels for integrin α3. Silencing β1 increased cell number with reduced osteocalcin and osteoprotegerin in a wettability-dependent manner. Surface wettability as a primary regulator enhanced osteoblast differentiation, but integrin expression and silencing β1 results indicate that surface wettability regulates osteoblast through differential integrin expression profiles than microtexture does. The results may indicate that both microtexture and wettability with a specific chemistry have

  13. Functional test of PCDHB11, the most human-specific neuronal surface protein.

    Science.gov (United States)

    de Freitas, Guilherme Braga; Gonçalves, Rafaella Araújo; Gralle, Matthias

    2016-04-12

    Brain-expressed proteins that have undergone functional change during human evolution may contribute to human cognitive capacities, and may also leave us vulnerable to specifically human diseases, such as schizophrenia, autism or Alzheimer's disease. In order to search systematically for those proteins that have changed the most during human evolution and that might contribute to brain function and pathology, all proteins with orthologs in chimpanzee, orangutan and rhesus macaque and annotated as being expressed on the surface of cells in the human central nervous system were ordered by the number of human-specific amino acid differences that are fixed in modern populations. PCDHB11, a beta-protocadherin homologous to murine cell adhesion proteins, stood out with 12 substitutions and maintained its lead after normalizing for protein size and applying weights for amino acid exchange probabilities. Human PCDHB11 was found to cause homophilic cell adhesion, but at lower levels than shown for other clustered protocadherins. Homophilic adhesion caused by a PCDHB11 with reversion of human-specific changes was as low as for modern human PCDHB11; while neither human nor reverted PCDHB11 adhered to controls, they did adhere to each other. A loss of function in PCDHB11 is unlikely because intra-human variability did not increase relative to the other human beta-protocadherins. The brain-expressed protein with the highest number of human-specific substitutions is PCDHB11. In spite of its fast evolution and low intra-human variability, cell-based tests on the only proposed function for PCDHB11 did not indicate a functional change.

  14. HadISDH: an updateable land surface specific humidity product for climate monitoring

    Directory of Open Access Journals (Sweden)

    K. M. Willett

    2013-03-01

    Full Text Available HadISDH is a near-global land surface specific humidity monitoring product providing monthly means from 1973 onwards over large-scale grids. Presented herein to 2012, annual updates are anticipated. HadISDH is an update to the land component of HadCRUH, utilising the global high-resolution land surface station product HadISD as a basis. HadISD, in turn, uses an updated version of NOAA's Integrated Surface Database. Intensive automated quality control has been undertaken at the individual observation level, as part of HadISD processing. The data have been subsequently run through the pairwise homogenisation algorithm developed for NCDC's US Historical Climatology Network monthly temperature product. For the first time, uncertainty estimates are provided at the grid-box spatial scale and monthly timescale. HadISDH is in good agreement with existing land surface humidity products in periods of overlap, and with both land air and sea surface temperature estimates. Widespread moistening is shown over the 1973–2012 period. The largest moistening signals are over the tropics with drying over the subtropics, supporting other evidence of an intensified hydrological cycle over recent years. Moistening is detectable with high (95% confidence over large-scale averages for the globe, Northern Hemisphere and tropics, with trends of 0.089 (0.080 to 0.098 g kg−1 per decade, 0.086 (0.075 to 0.097 g kg−1 per decade and 0.133 (0.119 to 0.148 g kg−1 per decade, respectively. These changes are outside the uncertainty range for the large-scale average which is dominated by the spatial coverage component; station and grid-box sampling uncertainty is essentially negligible on large scales. A very small moistening (0.013 (−0.005 to 0.031 g kg−1 per decade is found in the Southern Hemisphere, but it is not significantly different from zero and uncertainty is large. When globally averaged, 1998 is the moistest year since monitoring began in 1973, closely

  15. HadISDH: an updateable land surface specific humidity product for climate monitoring

    Science.gov (United States)

    Willett, K. M.; Williams, C. N., Jr.; Dunn, R. J. H.; Thorne, P. W.; Bell, S.; de Podesta, M.; Jones, P. D.; Parker, D. E.

    2013-03-01

    HadISDH is a near-global land surface specific humidity monitoring product providing monthly means from 1973 onwards over large-scale grids. Presented herein to 2012, annual updates are anticipated. HadISDH is an update to the land component of HadCRUH, utilising the global high-resolution land surface station product HadISD as a basis. HadISD, in turn, uses an updated version of NOAA's Integrated Surface Database. Intensive automated quality control has been undertaken at the individual observation level, as part of HadISD processing. The data have been subsequently run through the pairwise homogenisation algorithm developed for NCDC's US Historical Climatology Network monthly temperature product. For the first time, uncertainty estimates are provided at the grid-box spatial scale and monthly timescale. HadISDH is in good agreement with existing land surface humidity products in periods of overlap, and with both land air and sea surface temperature estimates. Widespread moistening is shown over the 1973-2012 period. The largest moistening signals are over the tropics with drying over the subtropics, supporting other evidence of an intensified hydrological cycle over recent years. Moistening is detectable with high (95%) confidence over large-scale averages for the globe, Northern Hemisphere and tropics, with trends of 0.089 (0.080 to 0.098) g kg-1 per decade, 0.086 (0.075 to 0.097) g kg-1 per decade and 0.133 (0.119 to 0.148) g kg-1 per decade, respectively. These changes are outside the uncertainty range for the large-scale average which is dominated by the spatial coverage component; station and grid-box sampling uncertainty is essentially negligible on large scales. A very small moistening (0.013 (-0.005 to 0.031) g kg-1 per decade) is found in the Southern Hemisphere, but it is not significantly different from zero and uncertainty is large. When globally averaged, 1998 is the moistest year since monitoring began in 1973, closely followed by 2010, two strong El

  16. ANALYSIS OF HIGH FIELD NON-LINEAR LOSSES ON SRF SURFACES DUE TO SPECIFIC TOPOGRAPHIC ROUGHNESS

    Energy Technology Data Exchange (ETDEWEB)

    Chen Xu,Charles Reece,Michael Kelley

    2012-07-01

    The high-field performance of SRF cavities will eventually be limited by the realization of fundamental material limits, whether it is Hc1 or Hsh, or some derivative thereof, at which the superconductivity is lost. Before reaching this fundamental field limit at the macro level, it must be encountered at localized, perhaps microscopic, sites of field enhancement due to local topography. If such sites are small enough, they may produce thermally stabilized normal-conducting regions which contribute non-linear losses when viewed from the macro resonant field perspective, and thus produce degradation in Q0. We have undertaken a calculation of local surface magnetic field enhancement from specific fine topographic structure by conformal mapping method and numerically. A solution of the resulting normal conducting volume has been derived and the corresponding RF Ohmic loss simulated.

  17. Soil Specific Surface Area and Non-Singularity of Soil-Water Retention at Low Saturations

    DEFF Research Database (Denmark)

    Arthur, Emmanuel; Tuller, Markus; Møldrup, Per

    2013-01-01

    and Or (TO) and new single-parameter non-singularity (SPN) models; and evaluate estimates of SSA from water sorption, ethylene glycol monoethyl ether (EGME), and N2–BET methods. The AquaSorp successfully measured water sorption isotherms (∼140 data points) within a reasonably short time (1–3 d). The SPN......The dry end of the soil water characteristic (SWC) is important for modeling vapor flow dynamics and predicting soil properties such as specific surface area (SSA) and clay content (CL). Verification of new instrumentation for rapid measurement of the dry end of the SWC is relevant to avoid long...... model well described the distinct non-singularity between the adsorption and desorption branches, while the TO model captured the adsorption data reasonably well (model were...

  18. Excimer laser texturing of natural composite polymer surfaces for studying cell-to-substrate specific response

    Science.gov (United States)

    Dinca, V.; Alloncle, P.; Delaporte, P.; Ion, V.; Rusen, L.; Filipescu, M.; Mustaciosu, C.; Luculescu, C.; Dinescu, M.

    2015-10-01

    Surface modifications of biocompatible materials are among the main factors used for enhancing and promoting specific cellular activities (e.g. spreading, adhesion, migration, and differentiation) for various types of medical applications such as implants, microfluidic devices, or tissue engineering scaffolds. In this work an excimer laser at 193 nm was used to fabricate chitosan-collagen roughness gradients. The roughness gradients were obtained in one step by applying single laser pulses and sample tilting. Fourier transform infrared spectroscopy measurements, atomic force microscopy (AFM), scanning electron microscopy (SEM), and spectro-ellipsometry (SE) were used for sample characterization. The goal is to determine the optimal morpho-chemical characteristics of these structures for in vitro tailoring of protein adsorption and cell behavior. The response induced by the roughness gradient onto various cell lines (i.e. L 929 fibroblasts, HEP G2 hepatocytes, OLN 93 oligodendrocytes, M63 osteoblasts) and bovine serum albumin (BSA) protein absorption was investigated.

  19. High specific surface area Mo2C nanoparticles as an efficient electrocatalyst for hydrogen evolution

    Science.gov (United States)

    Tang, Chaoyun; Sun, Aokui; Xu, Yushuai; Wu, Zhuangzhi; Wang, Dezhi

    2015-11-01

    Mo2C nanoparticles with high specific surface area (120 m2 g-1) are successfully synthesized using a typical and low-cost monosaccharide of glucose via a facile calcination and subsequent reduction process. The HER functions of the obtained Mo2C nanoparticles are investigated and the effect of reduction time in hydrogen is also discussed. It is found that η-MoC can be obtained at 800 °C with a reduction time of 10 min, but the formation of β-Mo2C phase requires more than 20 min. Moreover, the β-Mo2C obtained with a reduction time of 20 min exhibits the best HER activity with a small Tafel slope of 55 mV dec-1 and a large current density of 60 mA cm-2 at -200 mV, which is among the best records over Mo2C-based HER catalysts.

  20. Phonons on the clean metal surfaces and in adsorption structures

    Science.gov (United States)

    Rusina, Galina G.; Chulkov, Evgenii V.

    2013-06-01

    The state-of-the-art studies of the vibrational dynamics of clean metal surfaces and metal surface structures formed upon the sub-monolayer adsorption of the atoms of various elements are considered. A brief historical survey of the milestones of investigations of surface phonons is presented. The results of studies of the atomic structure and vibration characteristics of surfaces with low and high Miller indices and adsorption structures are analyzed. It is demonstrated that vicinal surfaces of FCC metals tend to exhibit specific vibrational modes located on the step and polarized along the step. Irrespective of the type and position of adsorption or the substrate structure, the phonon spectra of sub-monolayer adsorption structures always tend to display two modes for combined translational displacements of adatoms and for coupled vibrations of substrate atoms and adatoms polarized in the direction normal to the surface. The bibliography includes 202 references.

  1. Analysis of bacterial-surface-specific antibodies in body fluids using bacterial flow cytometry.

    Science.gov (United States)

    Moor, Kathrin; Fadlallah, Jehane; Toska, Albulena; Sterlin, Delphine; Balmer, Maria L; Macpherson, Andrew J; Gorochov, Guy; Larsen, Martin; Slack, Emma

    2016-08-01

    Antibacterial antibody responses that target surfaces of live bacteria or secreted toxins are likely to be relevant in controlling bacterial pathogenesis. The ability to specifically quantify bacterial-surface-binding antibodies is therefore highly attractive as a quantitative correlate of immune protection. Here, binding of antibodies from various body fluids to pure-cultured live bacteria is made visible with fluorophore-conjugated secondary antibodies and measured by flow cytometry. We indicate the necessary controls for excluding nonspecific binding and also demonstrate a cross-adsorption technique for determining the extent of cross-reactivity. This technique has numerous advantages over standard ELISA and western blotting techniques because of its independence from scaffold binding, exclusion of cross-reactive elements from lysed bacteria and ability to visualize bacterial subpopulations. In addition, less than 10(5) bacteria and less than 10 μg of antibody are required per sample. The technique requires 3-4 h of hands-on experimentation and analysis. Moreover, it can be combined with automation and mutliplexing for high-throughput applications.

  2. Femtosecond nonlinear spectroscopy at surfaces: Second-harmonic probing of hole burning at the Si(111)7x7 surface and fourier-transform sum-frequency vibrational spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    McGuire, John Andrew [Univ. of California, Berkeley, CA (United States)

    2004-11-24

    The high temporal resolution and broad bandwidth of a femtosecond laser system are exploited in a pair of nonlinear optical studies of surfaces. The dephasing dynamics of resonances associated with the adatom dangling bonds of the Si(111)7 x 7 surface are explored by transient second-harmonic hole burning, a process that can be described as a fourth-order nonlinear optical process. Spectral holes produced by a 100 fs pump pulse at about 800 nm are probed by the second harmonic signal of a 100 fs pulse tunable around 800 nm. The measured spectral holes yield homogeneous dephasing times of a few tens of femtoseconds. Fits with a Lorentzian spectral hole centered at zero probe detuning show a linear dependence of the hole width on pump fluence, which suggests that charge carrier-carrier scattering dominates the dephasing dynamics at the measured excitation densities. Extrapolation of the deduced homogeneous dephasing times to zero excitation density yields an intrinsic dephasing time of {approx} 70 fs. The presence of a secondary spectral hole indicates that scattering of the surface electrons with surface optical phonons at 570 cm-1 occurs within the first 200 fs after excitation. The broad bandwidth of femtosecond IR pulses is used to perform IR-visible sum frequency vibrational spectroscopy. By implementing a Fourier-transform technique, we demonstrate the ability to obtain sub-laser-bandwidth spectral resolution. FT-SFG yields a greater signal when implemented with a stretched visible pulse than with a femtosecond visible pulse. However, when compared with multichannel spectroscopy using a femtosecond IR pulse but a narrowband visible pulse, Fourier-transform SFG is found to have an inferior signal-to-noise ratio. A mathematical analysis of the signal-to-noise ratio illustrates the constraints on the Fourier-transform approach.

  3. Enzyme-Linked Immunosorbent Assays for Detection of Equine Antibodies Specific to Sarcocystis neurona Surface Antigens†

    Science.gov (United States)

    Hoane, Jessica S.; Morrow, Jennifer K.; Saville, William J.; Dubey, J. P.; Granstrom, David E.; Howe, Daniel K.

    2005-01-01

    Sarcocystis neurona is the primary causative agent of equine protozoal myeloencephalitis (EPM), a common neurologic disease of horses in the Americas. We have developed a set of enzyme-linked immunosorbent assays (ELISAs) based on the four major surface antigens of S. neurona (SnSAGs) to analyze the equine antibody response to S. neurona. The SnSAG ELISAs were optimized and standardized with a sample set of 36 equine sera that had been characterized by Western blotting against total S. neurona parasite antigen, the current gold standard for S. neurona serology. The recombinant SnSAG2 (rSnSAG2) ELISA showed the highest sensitivity and specificity at 95.5% and 92.9%, respectively. In contrast, only 68.2% sensitivity and 71.4% specificity were achieved with the rSnSAG1 ELISA, indicating that this antigen may not be a reliable serological marker for analyzing antibodies against S. neurona in horses. Importantly, the ELISA antigens did not show cross-reactivity with antisera to Sarcocystis fayeri or Neospora hughesi, two other equine parasites. The accuracy and reliability exhibited by the SnSAG ELISAs suggest that these assays will be valuable tools for examining the equine immune response against S. neurona infection, which may help in understanding the pathobiology of this accidental parasite-host interaction. Moreover, with modification and further investigation, the SnSAG ELISAs have potential for use as immunodiagnostic tests to aid in the identification of horses affected by EPM. PMID:16148170

  4. Enzyme-linked immunosorbent assays for detection of equine antibodies specific to Sarcocystis neurona surface antigens.

    Science.gov (United States)

    Hoane, Jessica S; Morrow, Jennifer K; Saville, William J; Dubey, J P; Granstrom, David E; Howe, Daniel K

    2005-09-01

    Sarcocystis neurona is the primary causative agent of equine protozoal myeloencephalitis (EPM), a common neurologic disease of horses in the Americas. We have developed a set of enzyme-linked immunosorbent assays (ELISAs) based on the four major surface antigens of S. neurona (SnSAGs) to analyze the equine antibody response to S. neurona. The SnSAG ELISAs were optimized and standardized with a sample set of 36 equine sera that had been characterized by Western blotting against total S. neurona parasite antigen, the current gold standard for S. neurona serology. The recombinant SnSAG2 (rSnSAG2) ELISA showed the highest sensitivity and specificity at 95.5% and 92.9%, respectively. In contrast, only 68.2% sensitivity and 71.4% specificity were achieved with the rSnSAG1 ELISA, indicating that this antigen may not be a reliable serological marker for analyzing antibodies against S. neurona in horses. Importantly, the ELISA antigens did not show cross-reactivity with antisera to Sarcocystis fayeri or Neospora hughesi, two other equine parasites. The accuracy and reliability exhibited by the SnSAG ELISAs suggest that these assays will be valuable tools for examining the equine immune response against S. neurona infection, which may help in understanding the pathobiology of this accidental parasite-host interaction. Moreover, with modification and further investigation, the SnSAG ELISAs have potential for use as immunodiagnostic tests to aid in the identification of horses affected by EPM.

  5. Reliable nanomaterial classification of powders using the volume-specific surface area method

    Science.gov (United States)

    Wohlleben, Wendel; Mielke, Johannes; Bianchin, Alvise; Ghanem, Antoine; Freiberger, Harald; Rauscher, Hubert; Gemeinert, Marion; Hodoroaba, Vasile-Dan

    2017-02-01

    The volume-specific surface area (VSSA) of a particulate material is one of two apparently very different metrics recommended by the European Commission for a definition of "nanomaterial" for regulatory purposes: specifically, the VSSA metric may classify nanomaterials and non-nanomaterials differently than the median size in number metrics, depending on the chemical composition, size, polydispersity, shape, porosity, and aggregation of the particles in the powder. Here we evaluate the extent of agreement between classification by electron microscopy (EM) and classification by VSSA on a large set of diverse particulate substances that represent all the anticipated challenges except mixtures of different substances. EM and VSSA are determined in multiple labs to assess also the level of reproducibility. Based on the results obtained on highly characterized benchmark materials from the NanoDefine EU FP7 project, we derive a tiered screening strategy for the purpose of implementing the definition of nanomaterials. We finally apply the screening strategy to further industrial materials, which were classified correctly and left only borderline cases for EM. On platelet-shaped nanomaterials, VSSA is essential to prevent false-negative classification by EM. On porous materials, approaches involving extended adsorption isotherms prevent false positive classification by VSSA. We find no false negatives by VSSA, neither in Tier 1 nor in Tier 2, despite real-world industrial polydispersity and diverse composition, shape, and coatings. The VSSA screening strategy is recommended for inclusion in a technical guidance for the implementation of the definition.

  6. Generation and tumor recognition properties of two human monoclonal antibodies specific to cell surface anionic phospholipids.

    Science.gov (United States)

    Bujak, Emil; Pretto, Francesca; Neri, Dario

    2015-08-01

    Phosphatidylserine (PS) and other anionic phospholipids, which become exposed on the surface of proliferating endothelial cells, tumor cells and certain leukocytes, have been used as targets for the development of clinical-stage biopharmaceuticals. One of these products (bavituximab) is currently being investigated in Phase 3 clinical trials. There are conflicting reports on the ability of bavituximab and other antibodies to recognize PS directly or through beta-2 glycoprotein 1, a serum protein that is not highly conserved across species. Here, we report on the generation and characterization of two fully human antibodies directed against phosphatidylserine. One of these antibodies (PS72) bound specifically to phosphatidylserine and to phosphatidic acid, but did not recognize other closely related phospholipids, while the other antibody (PS41) also bound to cardiolipin. Both PS72 and PS41 stained 8/9 experimental tumor models in vitro, but both antibodies failed to exhibit a preferential tumor accumulation in vivo, as revealed by quantitative biodistribution analysis. Our findings indicate that anionic phospholipids are exposed and accessible in most tumor types, but cast doubts about the possibility of efficiently targeting tumors in vivo with PS-specific reagents.

  7. Real-time specific surface area measurements via laser-induced breakdown spectroscopy

    Science.gov (United States)

    Washburn, Kathryn E.; Birdwell, Justin E.; Howard, James E.

    2017-01-01

    From healthcare to cosmetics to environmental science, the specific surface area (SSA) of micro- and mesoporous materials or products can greatly affect their chemical and physical properties. SSA results are also widely used to examine source rocks in conventional and unconventional petroleum resource plays. Despite its importance, current methods to measure SSA are often cumbersome, time-consuming, or require cryogenic consumables (e.g., liquid nitrogen). These methods are not amenable to high-throughput environments, have stringent sample preparation requirements, and are not practical for use in the field. We present a new application of laser-induced breakdown spectroscopy for rapid measurement of SSA. This study evaluates geological samples, specifically organic-rich oil shales, but the approach is expected to be applicable to many other types of materials. The method uses optical emission spectroscopy to examine laser-generated plasma and quantify the amount of argon adsorbed to a sample during an inert gas purge. The technique can accommodate a wide range of sample sizes and geometries and has the potential for field use. These advantages for SSA measurement combined with the simultaneous acquisition of composition information make this a promising new approach for characterizing geologic samples and other materials.

  8. The Fanconi anemia associated protein FAAP24 uses two substrate specific binding surfaces for DNA recognition.

    Science.gov (United States)

    Wienk, Hans; Slootweg, Jack C; Speerstra, Sietske; Kaptein, Robert; Boelens, Rolf; Folkers, Gert E

    2013-07-01

    To maintain the integrity of the genome, multiple DNA repair systems exist to repair damaged DNA. Recognition of altered DNA, including bulky adducts, pyrimidine dimers and interstrand crosslinks (ICL), partially depends on proteins containing helix-hairpin-helix (HhH) domains. To understand how ICL is specifically recognized by the Fanconi anemia proteins FANCM and FAAP24, we determined the structure of the HhH domain of FAAP24. Although it resembles other HhH domains, the FAAP24 domain contains a canonical hairpin motif followed by distorted motif. The HhH domain can bind various DNA substrates; using nuclear magnetic resonance titration experiments, we demonstrate that the canonical HhH motif is required for double-stranded DNA (dsDNA) binding, whereas the unstructured N-terminus can interact with single-stranded DNA. Both DNA binding surfaces are used for binding to ICL-like single/double-strand junction-containing DNA substrates. A structural model for FAAP24 bound to dsDNA has been made based on homology with the translesion polymerase iota. Site-directed mutagenesis, sequence conservation and charge distribution support the dsDNA-binding model. Analogous to other HhH domain-containing proteins, we suggest that multiple FAAP24 regions together contribute to binding to single/double-strand junction, which could contribute to specificity in ICL DNA recognition.

  9. Nickel catalysts supported on MgO with different specific surface area for carbon dioxide reforming of methane

    Institute of Scientific and Technical Information of China (English)

    Luming; Zhang; Lin; Li; Yuhua; Zhang; Yanxi; Zhao; Jinlin; Li

    2014-01-01

    In this paper, three kinds of MgO with different specific surface area were prepared, and their effects on the catalytic performance of nickel catalysts for the carbon dioxide reforming of methane were investigated. The results showed that MgO support with the higher specific surface area led to the higher dispersion of the active metal, which resulted in the higher initial activity. On the other hand, the specific surface area of MgO materials might not be the dominant factor for the basicity of support to chemisorb and activate CO2, which was another important factor for the performance of catalysts. Herein, Ni/MgO(CA) catalyst with proper specific surface area and strong ability to activate CO2exhibited stable catalytic property and the carbon species deposited on the Ni/MgO(CA) catalyst after 10 h of reaction at 650 ?C were mainly activated carbon species.

  10. Vertical profiles of the specific surface area of the snow at Dome C, Antarctica

    Directory of Open Access Journals (Sweden)

    J.-C. Gallet

    2010-09-01

    Full Text Available The specific surface area (SSA of snow determines in Part the albedo of snow surfaces and the capacity of the snow to adsorb chemical species and catalyze reactions. Despite these crucial roles, almost no value of snow SSA are available for the largest permanent snow expanse on Earth, the Antarctic. We have measured the first vertical profiles of snow SSA near Dome C (DC: 75°06´ S, 123°20´ E, 3233 m a.s.l. on the Antarctic plateau, and at seven sites during the logistical traverse between Dome C and the French coastal base Dumont D'Urville (DDU: 66°40´ S, 140°01´ E during the Austral summer 2008–2009. We used the DUFISSS system, which measures the IR reflectance of snow at 1310 nm with an integrating sphere. At DC, the mean SSA of the snow in the top 1 cm is 38 m2 kg−1, decreasing monotonically to 14 m2 kg−1 at a depth of 15 cm. Along the traverse, the snow SSA profile is similar to that at DC in the first 600 km from DC. Closer to DDU, the SSA of the top 5 cm is 23 m2 kg−1, decreasing to 19 m2 kg−1 at 50 cm depth. This is attributed to wind, which causes a rapid decrease of surface snow SSA, but forms hard windpacks whose SSA decrease more slowly with time. Since light-absorbing impurities are not concentrated enough to affect albedo, the vertical profiles of SSA and density were used to calculate the spectral albedo of the snow for several realistic illumination conditions, using the DISORT radiative transfer model. A preliminary comparison with MODIS data is presented for use in energy balance calculations and for comparison with other satellite retrievals. These calculated albedos are compared to the few existing measurements on the Antarctic plateau. The interest of postulating a submillimetric, high-SSA layer at the snow surface to explain measured albedos is discussed.

  11. Leishmania-specific surface antigens show sub-genus sequence variation and immune recognition.

    Directory of Open Access Journals (Sweden)

    Daniel P Depledge

    Full Text Available BACKGROUND: A family of hydrophilic acylated surface (HASP proteins, containing extensive and variant amino acid repeats, is expressed at the plasma membrane in infective extracellular (metacyclic and intracellular (amastigote stages of Old World Leishmania species. While HASPs are antigenic in the host and can induce protective immune responses, the biological functions of these Leishmania-specific proteins remain unresolved. Previous genome analysis has suggested that parasites of the sub-genus Leishmania (Viannia have lost HASP genes from their genomes. METHODS/PRINCIPAL FINDINGS: We have used molecular and cellular methods to analyse HASP expression in New World Leishmania mexicana complex species and show that, unlike in L. major, these proteins are expressed predominantly following differentiation into amastigotes within macrophages. Further genome analysis has revealed that the L. (Viannia species, L. (V. braziliensis, does express HASP-like proteins of low amino acid similarity but with similar biochemical characteristics, from genes present on a region of chromosome 23 that is syntenic with the HASP/SHERP locus in Old World Leishmania species and the L. (L. mexicana complex. A related gene is also present in Leptomonas seymouri and this may represent the ancestral copy of these Leishmania-genus specific sequences. The L. braziliensis HASP-like proteins (named the orthologous (o HASPs are predominantly expressed on the plasma membrane in amastigotes and are recognised by immune sera taken from 4 out of 6 leishmaniasis patients tested in an endemic region of Brazil. Analysis of the repetitive domains of the oHASPs has shown considerable genetic variation in parasite isolates taken from the same patients, suggesting that antigenic change may play a role in immune recognition of this protein family. CONCLUSIONS/SIGNIFICANCE: These findings confirm that antigenic hydrophilic acylated proteins are expressed from genes in the same chromosomal

  12. Generalized Free-Surface Effect and Random Vibration Theory: a new tool for computing moment magnitudes of small earthquakes using borehole data

    Science.gov (United States)

    Malagnini, Luca; Dreger, Douglas S.

    2016-07-01

    Although optimal, computing the moment tensor solution is not always a viable option for the calculation of the size of an earthquake, especially for small events (say, below Mw 2.0). Here we show an alternative approach to the calculation of the moment-rate spectra of small earthquakes, and thus of their scalar moments, that uses a network-based calibration of crustal wave propagation. The method works best when applied to a relatively small crustal volume containing both the seismic sources and the recording sites. In this study we present the calibration of the crustal volume monitored by the High-Resolution Seismic Network (HRSN), along the San Andreas Fault (SAF) at Parkfield. After the quantification of the attenuation parameters within the crustal volume under investigation, we proceed to the spectral correction of the observed Fourier amplitude spectra for the 100 largest events in our data set. Multiple estimates of seismic moment for the all events (1811 events total) are obtained by calculating the ratio of rms-averaged spectral quantities based on the peak values of the ground velocity in the time domain, as they are observed in narrowband-filtered time-series. The mathematical operations allowing the described spectral ratios are obtained from Random Vibration Theory (RVT). Due to the optimal conditions of the HRSN, in terms of signal-to-noise ratios, our network-based calibration allows the accurate calculation of seismic moments down to Mw < 0. However, because the HRSN is equipped only with borehole instruments, we define a frequency-dependent Generalized Free-Surface Effect (GFSE), to be used instead of the usual free-surface constant F = 2. Our spectral corrections at Parkfield need a different GFSE for each side of the SAF, which can be quantified by means of the analysis of synthetic seismograms. The importance of the GFSE of borehole instruments increases for decreasing earthquake's size because for smaller earthquakes the bandwidth available

  13. Enteroendocrine cells are specifically marked by cell surface expression of claudin-4 in mouse small intestine.

    Directory of Open Access Journals (Sweden)

    Takahiro Nagatake

    Full Text Available Enteroendocrine cells are solitary epithelial cells scattered throughout the gastrointestinal tract and produce various types of hormones, constituting one of the largest endocrine systems in the body. The study of these rare epithelial cells has been hampered by the difficulty in isolating them because of the lack of specific cell surface markers. Here, we report that enteroendocrine cells selectively express a tight junction membrane protein, claudin-4 (Cld4, and are efficiently isolated with the use of an antibody specific for the Cld4 extracellular domain and flow cytometry. Sorted Cld4+ epithelial cells in the small intestine exclusively expressed a chromogranin A gene (Chga and other enteroendocrine cell-related genes (Ffar1, Ffar4, Gpr119, and the population was divided into two subpopulations based on the activity of binding to Ulex europaeus agglutinin-1 (UEA-1. A Cld4+UEA-1- cell population almost exclusively expressed glucose-dependent insulinotropic polypeptide gene (Gip, thus representing K cells, whereas a Cld4+UEA-1+ cell population expressed other gut hormone genes, including glucagon-like peptide 1 (Gcg, pancreatic polypeptide-like peptide with N-terminal tyrosine amide (Pyy, cholecystokinin (Cck, secretin (Sct, and tryptophan hydroxylase 1 (Tph1. In addition, we found that orally administered luminal antigens were taken up by the solitary Cld4+ cells in the small intestinal villi, raising the possibility that enteroendocrine cells might also play a role in initiation of mucosal immunity. Our results provide a useful tool for the cellular and functional characterization of enteroendocrine cells.

  14. In Situ Adsorption Studies at the Solid/Liquid Interface:Characterization of Biological Surfaces and Interfaces Using SumFrequency Generation Vibrational Spectroscopy, Atomic Force Microscopy,and Quartz Crystal Microbalance

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, Diana Christine [Univ. of California, Berkeley, CA (United States)

    2006-01-01

    Sum frequency generation (SFG) vibrational spectroscopy, atomic force microscopy (AFM), and quartz crystal microbalance (QCM) have been used to study the molecular surface structure, surface topography and mechanical properties, and quantitative adsorbed amount of biological molecules at the solid-liquid interface. The molecular-level behavior of designed peptides adsorbed on hydrophobic polystyrene and hydrophilic silica substrates has been examined as a model of protein adsorption on polymeric biomaterial surfaces. Proteins are such large and complex molecules that it is difficult to identify the features in their structure that lead to adsorption and interaction with solid surfaces. Designed peptides which possess secondary structure provide simple model systems for understanding protein adsorption. Depending on the amino acid sequence of a peptide, different secondary structures (α-helix and β-sheet) can be induced at apolar (air/liquid or air/solid) interfaces. Having a well-defined secondary structure allows experiments to be carried out under controlled conditions, where it is possible to investigate the affects of peptide amino acid sequence and chain length, concentration, buffering effects, etc. on adsorbed peptide structure. The experiments presented in this dissertation demonstrate that SFG vibrational spectroscopy can be used to directly probe the interaction of adsorbing biomolecules with a surface or interface. The use of well designed model systems aided in isolation of the SFG signal of the adsorbing species, and showed that surface functional groups of the substrate are sensitive to surface adsorbates. The complementary techniques of AFM and QCM allowed for deconvolution of the effects of surface topography and coverage from the observed SFG spectra. Initial studies of biologically relevant surfaces are also presented: SFG spectroscopy was used to study the surface composition of common soil bacteria for use in bioremediation of nuclear waste.

  15. Laser induced structural vibration

    Science.gov (United States)

    Koss, L. L.; Tobin, R. C.

    1983-01-01

    A technique is described for exciting structural vibration by using a focussed laser beam to vaporize material from a target attached to the structure. The rapid ejection of material results in an impulsive reaction to the target which is transmitted to the structure. The method has been studied with a Nd: glass laser, operated in the long pulse mode, in combination with a bismuth target attached in turn to a ballistic pendulum and cantilever beam. The specific mechanical energy was found to be proportional to the laser pulse energy raised to a power in the range 2.5-2.9. The highest efficiency of energy transfer achieved for the first vibrational mode of the cantilever was about 2 millipercent for the maximum laser pulse energy used, 1.5 J, the signal to noise ratio then being about 40 dB.

  16. Detection of Influenza Virus with Specific Subtype by Using Localized Surface Plasmons Excited on a Flat Metal Surface

    Science.gov (United States)

    Ning, Jun; Nagata, Kotaro; Ainai, Akira; Hasegawa, Hideki; Kano, Hiroshi

    2013-08-01

    We report on a method to determine subtype of influenza viruses by using surface plasmons localized in microscopic region on a flat metal surface. In this method, refractive index variation arisen from interactions between viruses and their monoclonal antibodies is measured. The developed sensor shows stability of refractive index in the order of 10-4 against sample exchange. In our experiment, A/H1N1 viruses are distinguished from A/H3N2 viruses by using monoclonal antibodies immobilized on the metal surface. Since the measurement probe has the volume of ˜6 al, the method has potential to handle multiple subtypes in the measurement of a sample with ultra small volume.

  17. An examination of the vibration transmissibility of the hand-arm system in three orthogonal directions.

    Science.gov (United States)

    Welcome, Daniel E; Dong, Ren G; Xu, Xueyan S; Warren, Christopher; McDowell, Thomas W; Wu, John Z

    2015-02-01

    The objective of this study is to enhance the understanding of the vibration transmission in the hand-arm system in three orthogonal directions (X, Y, and Z). For the first time, the transmitted vibrations distributed on the entire hand-arm system exposed in the three orthogonal directions via a 3-D vibration test system were measured using a 3-D laser vibrometer. Seven adult male subjects participated in the experiment. This study confirms that the vibration transmissibility generally decreased with the increase in distance from the hand and it varied with the vibration direction. Specifically, to the upper arm and shoulder, only moderate vibration transmission was measured in the test frequency range (16 to 500 Hz), and virtually no transmission was measured in the frequency range higher than 50 Hz. The resonance vibration on the forearm was primarily in the range of 16-30 Hz with the peak amplitude of approximately 1.5 times of the input vibration amplitude. The major resonance on the dorsal surfaces of the hand and wrist occurred at around 30-40 Hz and, in the Y direction, with peak amplitude of more than 2.5 times of the input amplitude. At higher than 50 Hz, vibration transmission was effectively limited to the hand and fingers. A major finger resonance was observed at around 100 Hz in the X and Y directions and around 200 Hz in the Z direction. In the fingers, the resonance magnitude in the Z direction was generally the lowest, and the resonance magnitude in the Y direction was generally the highest with the resonance amplitude of 3 times the input vibration, which was similar to the transmissibility at the wrist and hand dorsum. The implications of the results are discussed.

  18. Identification of Pancreatic Cancer Specific Cell-Surface Markers for Development of Targeting Ligands

    Science.gov (United States)

    Morse, David L.; Hostetter, Galen; Balagurunathan, Yoganand; Gillies, Robert J.; Han, Haiyong

    2014-01-01

    Pancreatic cancer is generally detected at later stages with a poor prognosis and a high-mortality rate. Development of theranostic imaging agents that non-invasively target pancreatic cancer by gene expression and deliver therapies directly to malignant cells could greatly improve therapeutic outcomes. Small-peptide ligands that bind cell-surface proteins and are conjugated to imaging moieties have demonstrated efficacy in cancer imaging. Identification of cancer specific targets is a major bottleneck in the development of such agents. Herein, a method is presented that uses DNA microarray expression profiling of large sets of normal and cancer tissues to identify targets expressed in cancer but not expressed in relevant normal tissues. Identified targets are subsequently validated for protein expression using tissue microarray. Further validations are performed by quantifying expression in pancreatic cancer cells by quantitative real-time reverse-transcription polymerase chain reaction (qRT-PCR), by immunocytochemistry and immunohistochemistry and by reviewing data and literature in public databases. Validated targets are selected for ligand development based on the existence of a known ligand or by known structure activity relationships useful for development of novel ligands. PMID:20217597

  19. Upscaling of the specific surface area for reactive transport modelling in fractured rock

    Science.gov (United States)

    Cvetkovic, Vladimir

    2014-05-01

    The impact of flow heterogeneity on chemical transport from single to multiple fractures, is investigated. The emphasis is on the dynamic nature of the specific surface area (SSA) due to heterogeneity of the flow, relative to a purely geometrical definition. It is shown how to account for SSA as a random variable in modelling multi-component reactions. The flow-dependent SSA is interpreted probabilistically, following inert tracer particles along individual fractures. Upscaling to a fracture network is proposed as a time-domain random walk based on the statistics of SSA for single fractures. Statistics of SSA are investigated for three correlation structures of transmissivity, one classical multi-gaussian, and two non-Gaussian. The coefficient of variation of single fracture SSA decreases monotonously with the distance over the fracture length; the CV of the upscaled SSA reduces further such that after ca 20 fractures it is under 0.1 for a disconnected field, and around 0.2 for connected and multi-gaussian fields. This implies that after 10-20 fractures, uncertainty in SSA is significantly reduced, justifying the use of an effective value. A conservative, lower bound for the dimensionless upscaled effective SSA was found to be 1, suitable for all heterogeneity structures, assuming the cubic hydraulic law applicable.

  20. High specific surface gold electrode on polystyrene substrate: Characterization and application as DNA biosensor.

    Science.gov (United States)

    Yang, Zhiliu; Liu, Yichen; Lu, Wei; Yuan, Qingpan; Wang, Wei; Pu, Qiaosheng; Yao, Bo

    2016-05-15

    In the past decades, many efforts have been made to improve the sensitivity and specificity of electrochemical DNA biosensors. However, it is still strongly required to develop disposable and reliable DNA biosensors for wide and practical application. In this article, we reported superior electrochemical properties of an integrated plastic-gold electrode (PGE) fabricated in-house by chemical plating on polystyrene substrate. PGEs were found having extremely high capacity of DNA immobilization compared with gold electrodes fabricated by standard sputtering based photolithography. Unique nano-structured surface was observed on PGEs through morphology techniques, which would to some extend give an explanation to higher capacity of DNA immobilization on PGEs. A probable mechanism of carboxylic acid produced on polystyrene substrate after exposure to UV irradiation was proposed and discussed for the first time. This biosensor was applied to detection and manipulate of DNA hybridization. Detection limit of 7.2×10(-11) M and 1-500 nM of linearity range was obtained.

  1. Excimer laser texturing of natural composite polymer surfaces for studying cell-to-substrate specific response

    Energy Technology Data Exchange (ETDEWEB)

    Dinca, V., E-mail: dincavalentina@yahoo.com [NILPRP, National Institute for Lasers, Plasma and Radiation Physics, Magurele, Bucharest (Romania); Alloncle, P.; Delaporte, P. [Aix-Marseille University, CNRS, LP3 Laboratory, Campus de Luminy, 13288 Marseille (France); Ion, V. [NILPRP, National Institute for Lasers, Plasma and Radiation Physics, Magurele, Bucharest (Romania); Faculty of Physics, University of Bucharest, 077125 Magurele (Romania); Rusen, L.; Filipescu, M. [NILPRP, National Institute for Lasers, Plasma and Radiation Physics, Magurele, Bucharest (Romania); Mustaciosu, C. [Horia Hulubei National Institute of Physics and Nuclear Engineering – IFIN HH, Magurele, Bucharest (Romania); Luculescu, C.; Dinescu, M. [NILPRP, National Institute for Lasers, Plasma and Radiation Physics, Magurele, Bucharest (Romania)

    2015-10-15

    Highlights: • Roughness gradients are obtained in one step by applying single laser pulses and sample tilting. • BSA protein and cell dependence behavior onto gradient characteristics was studied. • The degradation of the samples by lysozyme was correlated to its ability to access the textured area. - Abstract: Surface modifications of biocompatible materials are among the main factors used for enhancing and promoting specific cellular activities (e.g. spreading, adhesion, migration, and differentiation) for various types of medical applications such as implants, microfluidic devices, or tissue engineering scaffolds. In this work an excimer laser at 193 nm was used to fabricate chitosan–collagen roughness gradients. The roughness gradients were obtained in one step by applying single laser pulses and sample tilting. Fourier transform infrared spectroscopy measurements, atomic force microscopy (AFM), scanning electron microscopy (SEM), and spectro-ellipsometry (SE) were used for sample characterization. The goal is to determine the optimal morpho-chemical characteristics of these structures for in vitro tailoring of protein adsorption and cell behavior. The response induced by the roughness gradient onto various cell lines (i.e. L 929 fibroblasts, HEP G2 hepatocytes, OLN 93 oligodendrocytes, M63 osteoblasts) and bovine serum albumin (BSA) protein absorption was investigated.

  2. Determination of specific binding interactions at L-cystine crystal surfaces with chemical force microscopy.

    Science.gov (United States)

    Mandal, Trinanjana; Ward, Michael D

    2013-04-17

    The pathogenesis of L-cystine kidney stones involves four critical steps: nucleation, crystal growth, crystal aggregation, and crystal adhesion to cells. Although inhibition of crystal growth by L-cystine "imposters" at L-cystine crystal surfaces has been suggested as a plausible route for the suppression of stones, understanding the factors that govern crystal-crystal aggregation and adhesion of crystals to epithelial cells also is essential for devising strategies to mitigate L-cystine stone formation. Chemical force microscopy performed with atomic force microscope tips decorated with functional groups commonly found in urinary constituents that likely mediate aggregation and attachment (e.g., COOH, NH2, SH, CH3, OH) revealed signatures that reflect differences in the chemical affinity of these groups for the (001) and {100} faces of the naturally occurring hexagonal form of L-cystine single crystals and the {110} faces of the non-native tetragonal form. These signatures can be explained by the different chemical compositions of the crystal faces, and they reveal a remarkable binding specificity of the thiol group for the sulfur-rich {100} and {110} faces of the hexagonal and tetragonal forms, respectively. Collectively, these observations suggest that alterations of the crystal habit and polymorph by crystal growth inhibitors may not affect crystal aggregation or adhesion to cells significantly.

  3. Retrieval of snow Specific Surface Area (SSA) from MODIS data in mountainous regions

    Science.gov (United States)

    Mary, A.; Dumont, M.; Dedieu, J.-P.; Durand, Y.; Sirguey, P.; Milhem, H.; Mestre, O.; Negi, H. S.; Kokhanovsky, A. A.

    2012-05-01

    This study describes a method to retrieve snow specific surface area (SSA) from satellite radiance reasurements in mountainous terrain. It aims at comparing different retrieval methods and at addressing topographic corrections of reflectance, namely slope and aspect of terrain and multiple reflections on neighbouring slopes. We use an iterative algorithm to compute reflectance from radiance of the MODerate resolution Imaging Spectrometer (MODIS) with a comprehensive correction of local illumination with regards to topography. The retrieved SSA is compared to the results of the snowpack model Crocus, fed by driving data from the SAFRAN meteorological analysis, over a large domain in the French Alps. We compared SSA retrievals with and without topographic or anisotropy correction, and with a spherical or non-spherical snow reflectance model. The topographic correction enables SSA to be retrieved in better agreement with those from SAFRAN-Crocus. The root mean square deviation is 10.0 m2 kg-1 and the bias is -0.6 m2 kg-1, over 3829 pixels representing seven different dates and snow conditions. The standard deviation of MODIS retrieved data, larger than the one of SAFRAN-Crocus estimates, is responsible for half this RMSD. It is due to the topographic classes used by SAFRAN-Crocus. In addition, MODIS retrieved data show SSA gradients with elevation and solar exposition, physically consistent and in good agreement with SAFRAN-Crocus.

  4. Retrieval of snow Specific Surface Area (SSA from MODIS data in mountainous regions

    Directory of Open Access Journals (Sweden)

    A. Mary

    2012-05-01

    Full Text Available This study describes a method to retrieve snow specific surface area (SSA from satellite radiance reasurements in mountainous terrain. It aims at comparing different retrieval methods and at addressing topographic corrections of reflectance, namely slope and aspect of terrain and multiple reflections on neighbouring slopes. We use an iterative algorithm to compute reflectance from radiance of the MODerate resolution Imaging Spectrometer (MODIS with a comprehensive correction of local illumination with regards to topography. The retrieved SSA is compared to the results of the snowpack model Crocus, fed by driving data from the SAFRAN meteorological analysis, over a large domain in the French Alps. We compared SSA retrievals with and without topographic or anisotropy correction, and with a spherical or non-spherical snow reflectance model. The topographic correction enables SSA to be retrieved in better agreement with those from SAFRAN-Crocus. The root mean square deviation is 10.0 m2 kg−1 and the bias is −0.6 m2 kg−1, over 3829 pixels representing seven different dates and snow conditions. The standard deviation of MODIS retrieved data, larger than the one of SAFRAN-Crocus estimates, is responsible for half this RMSD. It is due to the topographic classes used by SAFRAN-Crocus. In addition, MODIS retrieved data show SSA gradients with elevation and solar exposition, physically consistent and in good agreement with SAFRAN-Crocus.

  5. Molecular aspects of muco- and bioadhesion: tethered structures and site-specific surfaces.

    Science.gov (United States)

    Huang, Y; Leobandung, W; Foss, A; Peppas, N A

    2000-03-01

    Mucoadhesive controlled-release devices can improve the effectiveness of a drug by maintaining the drug concentration between the effective and toxic levels, inhibiting the dilution of the drug in the body fluids, and allowing targeting and localization of a drug at a specific site. Acrylic-based hydrogels have been used extensively as mucoadhesive systems. They are well suited for bioadhesion due to their flexibility and nonabrasive characteristics in the partially swollen state, which reduce damage-causing attrition to the tissues in contact. Crosslinked polymeric devices may be rendered adhesive to the mucosa. For example, adhesive capabilities of these hydrogels can be improved by tethering of long flexible chains to their surfaces. Tethering of long poly(ethylene glycol) (PEG) chains on poly(acrylic acid) hydrogels and their copolymers can be achieved by grafting reactions, or by copolymerization in the presence of several PEG-containing acrylates. The ensuing hydrogels exhibit mucoadhesive properties due to enhanced anchoring of the chains with the mucosa. Theoretical calculations can lead to optimization of the tethered structure. Experimental results indicate that the chain interpenetration is a strong function of the PEG molecular weight, the polymer swelling ratio and the mucosa composition.

  6. Measuring the specific surface area of wet snow using 1310 nm reflectance

    Directory of Open Access Journals (Sweden)

    J.-C. Gallet

    2013-10-01

    Full Text Available The specific surface area (SSA of snow can be used as an objective measurement of grain size and is therefore a central variable to describe snow physical properties such as albedo. Snow SSA can now be easily measured in the field using optical methods based on infrared reflectance. However, existing optical methods have only been validated for dry snow. Here we test the possibility to use the DUFISSS instrument, based on the measurement of the 1310 nm reflectance of snow with an integrating sphere, to measure the SSA of wet snow. We perform cold room experiments where we measure the SSA of a wet snow sample, freeze it and measure it again, to quantify the difference in reflectance between frozen and wet snow. We study snow samples in the SSA range 12–37 m2 kg−1 and in the mass liquid water content range 5–32%. We conclude that the SSA of wet snow can be obtained from the measurement of its 1310 nm reflectance using three simple steps. In most cases, the SSA thus obtained is less than 10% different from the value that would have been obtained if the sample had been considered dry, so that the three simple steps constitute a minor correction. We also run two optical models to interpret the results, but no model reproduces correctly the water-ice distribution in wet snow, so that their predictions of wet snow reflectance are imperfect.

  7. Surface functionalization of SPR chip for specific molecular interaction analysis under flow condition

    OpenAIRE

    Tao Ma; Xiaoxia Chen; Qing Peng; Pengfei Zhang; Yonghong He

    2017-01-01

    Surface functionalization of sensor chip for probe immobilization is crucial for the biosensing applications of surface plasmon resonance (SPR) sensors. In this paper, we report a method circulating the dopamine aqueous solution to coat polydopamine film on sensing surface for surface functionalization of SPR chip. The polydopamine film with available thickness can be easily prepared by controlling the circulation time and the biorecognition elements can be immobilized on the polydopamine fil...

  8. Increasing the Detection Limit of the Parkinson Disorder through a Specific Surface Chemistry Applied onto Inner Surface of the Titration Well

    Directory of Open Access Journals (Sweden)

    Fabienne Poncin-Epaillard

    2012-04-01

    Full Text Available The main objective of this paper was to illustrate the enhancement of the sensitivity of ELISA titration for neurodegenerative proteins by reducing nonspecific adsorptions that could lead to false positives. This goal was obtained thanks to the association of plasma and wet chemistries applied to the inner surface of the titration well. The polypropylene surface was plasma-activated and then, dip-coated with different amphiphilic molecules. These molecules have more or less long hydrocarbon chains and may be charged. The modified surfaces were characterized in terms of hydrophilic—phobic character, surface chemical groups and topography. Finally, the coated wells were tested during the ELISA titration of the specific antibody capture of the α-synuclein protein. The highest sensitivity is obtained with polar (Θ = 35°, negatively charged and smooth inner surface.

  9. Ground test for vibration control demonstrator

    Science.gov (United States)

    Meyer, C.; Prodigue, J.; Broux, G.; Cantinaud, O.; Poussot-Vassal, C.

    2016-09-01

    In the objective of maximizing comfort in Falcon jets, Dassault Aviation is developing an innovative vibration control technology. Vibrations of the structure are measured at several locations and sent to a dedicated high performance vibration control computer. Control laws are implemented in this computer to analyse the vibrations in real time, and then elaborate orders sent to the existing control surfaces to counteract vibrations. After detailing the technology principles, this paper focuses on the vibration control ground demonstration that was performed by Dassault Aviation in May 2015 on Falcon 7X business jet. The goal of this test was to attenuate vibrations resulting from fixed forced excitation delivered by shakers. The ground test demonstrated the capability to implement an efficient closed-loop vibration control with a significant vibration level reduction and validated the vibration control law design methodology. This successful ground test was a prerequisite before the flight test demonstration that is now being prepared. This study has been partly supported by the JTI CleanSky SFWA-ITD.

  10. Theory of vibration protection

    CERN Document Server

    Karnovsky, Igor A

    2016-01-01

    This text is an advancement of the theory of vibration protection of mechanical systems with lumped and distributed parameters. The book offers various concepts and methods of solving vibration protection problems, discusses the advantages and disadvantages of different methods, and the fields of their effective applications. Fundamental approaches of vibration protection, which are considered in this book, are the passive, parametric and optimal active vibration protection. The passive vibration protection is based on vibration isolation, vibration damping and dynamic absorbers. Parametric vibration protection theory is based on the Shchipanov-Luzin invariance principle. Optimal active vibration protection theory is based on the Pontryagin principle and the Krein moment method. The book also contains special topics such as suppression of vibrations at the source of their occurrence and the harmful influence of vibrations on humans. Numerous examples, which illustrate the theoretical ideas of each chapter, ar...

  11. 振动诱导微结构粗糙表面水滴Wenzel-Cassie状态转变特性%Vibration-induced Wenzel-Cassie wetting transition on rough patterned surface

    Institute of Scientific and Technical Information of China (English)

    贾志海; 雷威; 贺吉昌; 蔡泰民

    2014-01-01

    Superhydrophobic surfaces have aroused great attention for promising applications, e.g., enhanced heat transfer. The rough surface of square-shaped pillars was prepared from the polydimethyl-siloxane (PDMS) substrate by using photolithography technique. Based on the analysis of dynamic wetting characteristics of water droplets during vertical vibration, the Wenzel-Cassie wetting transition on the rough surface was studied with experimental and theoretical techniques. The experimental results showed that the Wenzel state droplets on the square-shaped pillars rough surface could change to the Cassie state when forced vibration frequency and amplitude were in the threshold range. When the eigenfrequency of the droplet was in accordance with forced vibration frequency, that is to say, at the resonance frequency, the forced vibration amplitude for Wenzel-Cassie wetting transition reached the lowest value. When forced vibration frequency was far from eigenfrequency, vibration amplitude was greater than the amplitude corresponding to resonance frequency. In the end, using the theory of surface chemistry, combining with vibration mechanics, a physical model was proposed to explain the Wenzel-Cassie wetting transition mechanism. This study could be potentially used to improve and control the heat transfer performance of dropwise condensation.%以聚二甲基硅氧烷(PDMS)基底采用光刻蚀技术制备了微方柱结构粗糙表面。采用高速摄影对液滴在垂直振动作用下的动态浸润状态进行了图像采集。通过对水滴振动过程中的动态浸润特性分析,研究了粗糙表面水滴的Wenzel-Cassie 浸润状态转变特征。结果表明,对于一定尺寸的 Wenzel 状态水滴,只有当施加的振动能量超过某一阈值时,微方柱粗糙表面Wenzel状态液滴才可以发生向Cassie状态的完全转变,且存在发生Wenzel-Cassie浸润转变的阈值范围;此外,当外加振动频率和液滴固有频率一致时

  12. LITERATURE REVIEW OF PUO2 CALCINATION TIME AND TEMPERATURE DATA FOR SPECIFIC SURFACE AREA

    Energy Technology Data Exchange (ETDEWEB)

    Daniel, G.

    2012-03-06

    The literature has been reviewed in December 2011 for calcination data of plutonium oxide (PuO{sub 2}) from plutonium oxalate Pu(C{sub 2}O{sub 4}){sub 2} precipitation with respect to the PuO{sub 2} specific surface area (SSA). A summary of the literature is presented for what are believed to be the dominant factors influencing SSA, the calcination temperature and time. The PuO{sub 2} from Pu(C{sub 2}O{sub 4}){sub 2} calcination data from this review has been regressed to better understand the influence of calcination temperature and time on SSA. Based on this literature review data set, calcination temperature has a bigger impact on SSA versus time. However, there is still some variance in this data set that may be reflecting differences in the plutonium oxalate preparation or different calcination techniques. It is evident from this review that additional calcination temperature and time data for PuO{sub 2} from Pu(C{sub 2}O{sub 4}){sub 2} needs to be collected and evaluated to better define the relationship. The existing data set has a lot of calcination times that are about 2 hours and therefore may be underestimating the impact of heating time on SSA. SRNL recommends that more calcination temperature and time data for PuO{sub 2} from Pu(C{sub 2}O{sub 4}){sub 2} be collected and this literature review data set be augmented to better refine the relationship between PuO{sub 2} SSA and its calcination parameters.

  13. Biodegradable polylactide microspheres enhance specific immune response induced by Hepatitis B surface antigen.

    Science.gov (United States)

    Qiu, Shaohui; Wei, Qiang; Liang, Zhenglun; Ma, Guanghui; Wang, Lianyan; An, Wenqi; Ma, Xiaowei; Fang, Xin; He, Peng; Li, Hemin; Hu, Zhongyu

    2014-01-01

    Hepatitis B (HB) infection caused by Hepatitis B virus (HBV) is the most common liver disease in the world. HB vaccine, when administered in conjunction with alum adjuvants, induces Th2 immunity that confers protection against HBV. However, currently available vaccine formulations and adjuvants do not elicit adequate Th1 and CTL responses that are important for prevention of maternal transmission of the virus. Microspheres synthesized from poly (D, L-lactide-co-glycolide) (PLGA) or poly (D, L-lactide) (PLA) polymers have been considered as promising tools for in vivo delivery of antigens and drugs. Here we describe PLA microspheres synthesized by premix membrane emulsification method and their application in formulating a new microsphere based HB vaccine. To evaluate the immunogenicity of this microsphere vaccine, BALB/c mice were immunized with microsphere vaccine and a series of immunological assays were conducted. Results of Enzyme-linked ImmunoSpot (ELISPOT) assays revealed that the number of interferon-gamma (IFN-γ)-producing splenocytes and CD8(+) T cells increased significantly in the microsphere vaccine group. Microsphere vaccine group showed enhanced specific cell lysis when compared with HB surface antigen (HBsAg) only group in (51)Cr cytotoxicity assays. Moreover, microsphere vaccine elicited a comparable level of antibody production as that of HB vaccine administered with alum adjuvant. We show that phagocytosis of HBsAg by dendritic cells is more pronounced in microsphere vaccine group when compared with other control groups. These results clearly demonstrate the potential of using PLA microspheres as effective HB vaccine adjuvants for an enhanced Th1 immune response.

  14. Super-multiplex vibrational imaging

    Science.gov (United States)

    Wei, Lu; Chen, Zhixing; Shi, Lixue; Long, Rong; Anzalone, Andrew V.; Zhang, Luyuan; Hu, Fanghao; Yuste, Rafael; Cornish, Virginia W.; Min, Wei

    2017-04-01

    The ability to visualize directly a large number of distinct molecular species inside cells is increasingly essential for understanding complex systems and processes. Even though existing methods have successfully been used to explore structure-function relationships in nervous systems, to profile RNA in situ, to reveal the heterogeneity of tumour microenvironments and to study dynamic macromolecular assembly, it remains challenging to image many species with high selectivity and sensitivity under biological conditions. For instance, fluorescence microscopy faces a ‘colour barrier’, owing to the intrinsically broad (about 1,500 inverse centimetres) and featureless nature of fluorescence spectra that limits the number of resolvable colours to two to five (or seven to nine if using complicated instrumentation and analysis). Spontaneous Raman microscopy probes vibrational transitions with much narrower resonances (peak width of about 10 inverse centimetres) and so does not suffer from this problem, but weak signals make many bio-imaging applications impossible. Although surface-enhanced Raman scattering offers high sensitivity and multiplicity, it cannot be readily used to image specific molecular targets quantitatively inside live cells. Here we use stimulated Raman scattering under electronic pre-resonance conditions to image target molecules inside living cells with very high vibrational selectivity and sensitivity (down to 250 nanomolar with a time constant of 1 millisecond). We create a palette of triple-bond-conjugated near-infrared dyes that each displays a single peak in the cell-silent Raman spectral window; when combined with available fluorescent probes, this palette provides 24 resolvable colours, with the potential for further expansion. Proof-of-principle experiments on neuronal co-cultures and brain tissues reveal cell-type-dependent heterogeneities in DNA and protein metabolism under physiological and pathological conditions, underscoring the

  15. Effects of ramp vibrational states on flexural intrinsic vibrations in Besocke-style scanners

    Institute of Scientific and Technical Information of China (English)

    Zhang Hui; Jiang Guo-Zhu; Liu Zhao-Qun; Zhang Shu-Yi; Fan Li

    2013-01-01

    For both the vibrating and steady supporting surfaces of a scanning disk in a Besocke-style piezoelectric scanner,a theoretical model is given by considering the nonlinear lateral friction at the micro-contact interface between the positioning legs and the supporting surface.Numerical simulations demonstrate that unexpected flexural vibrations can arise from a vibrating ramp,and their frequencies are lower than the eigenfrequencies of the scanner in the linearly elastic regime.The vibrations essentially depend on 1) the vibrational states of the supporting ramp and the steel ball tips on the three piezoelectric positioning legs,and 2) the tribological characteristics of the contacts between the tips and the ramp.The results give an insight into the intrinsic vibrations of the scanners,and are applicable in designing and optimizing piezoelectric scanning systems.

  16. Flow-induced detachment of red blood cells adhering to surfaces by specific antigen-antibody bonds.

    OpenAIRE

    Xia, Z; Goldsmith, H L; van de Ven, T G

    1994-01-01

    Fixed spherical swollen human red blood cells of blood type B adhering on a glass surface through antigen-antibody bonds to monoclonal mouse antihuman IgM, adsorbed or covalently linked on the surface, were detached by known hydrodynamic forces created in an impinging jet. The dynamic process of detachment of the specifically bound cells was recorded and analyzed. The fraction of adherent cells remaining on the surface decreased with increasing hydrodynamic force. For an IgM coverage of 0.26%...

  17. Cooperative triple-proton/hydrogen atom relay in 7-azaindole(CH3OH)2 in the gas phase: remarkable change in the reaction mechanism from vibrational-mode specific to statistical fashion with increasing internal energy.

    Science.gov (United States)

    Sakota, Kenji; Inoue, Naomi; Komoto, Yusuke; Sekiya, Hiroshi

    2007-05-31

    The 7-azaindole-methanol 1:2 cluster [7AI(CH(3)OH)2] undergoes excited-state triple-proton/hydrogen atom transfer (ESTPT/HT) along the hydrogen-bonded network in the gas phase. The measurements of the resonance-enhanced multiphoton ionization (REMPI) spectra of 7AI(CH(3)OH)2-d(n) (n = 0-3), where subscript n indicates the number of deuterium, and the fluorescence excitation spectrum of 7AI(CH(3)OH)2-d(0) allowed us to investigate the ESTPT/HT dynamics. By comparing the intensity ratios of the vibronic bands between 7AI(CH(3)OH)2-d(0) and 7AI(CH(3)OH)2-d(3) in REMPI spectra, we obtained the lower limit of an acceleration factor (f(a)(low)) of 7AI(CH(3)OH)2-d(0), which is the ratio of the reaction rate for the excitation of a vibronic state to that of the zero-point state in S(1). The f(a)(low) values are 2.7 +/- 0.83 and 4.0 +/- 1.2 for an in-phase intermolecular stretching vibration (sigma(1)) and its overtone (2sigma(1)) observed at 181 cm(-1) and 359 cm(-1) in the excitation spectrum, respectively, while that of the vibration (nu(2)/sigma(1) or nu(3)/sigma(1)) at 228 cm(-1) is 1.1 +/- 0.83. Thus, vibrational-mode-specific ESTPT/HT occurs in the low-energy region (600 cm(-1)). The excitation of an intramolecular ring mode (nu(intra)) of 7AI at 744 cm(-1) substantially enhances the reaction rate (f(a)(low) = 4.4 +/- 0.98), but the increase of f(a)(low) is not prominent for the excitation of v(intra) + sigma(1) at 926 cm(-1) (f(a)(low) = 5.0 +/- 1.6), although the sigma(1) mode is excited. These results suggest that the ESTPT/HT reaction in 7AI(CH(3)OH)2-d(0) directly proceeds from the photoexcited states with the internal energy less than approximately 600 cm(-1), but it occurs from the isoenergetically vibrational-energy redistributed states when the internal energy is large. This shows a remarkable feature of ESTPT/HT in 7AI(CH(3)OH)2; the nature of the reaction mechanism changes from vibrational-mode specific to statistical fashion with increasing the internal

  18. Cell surface domain specific postsynaptic currents evoked by identified GABAergic neurones in rat hippocampus in vitro.

    Science.gov (United States)

    Maccaferri, G; Roberts, J D; Szucs, P; Cottingham, C A; Somogyi, P

    2000-04-01

    of IPSCs evoked by BiCs and O-BiCs showed the largest cell to cell variation, and a single interneurone could evoke both small and slow as well as large and relatively fast IPSCs. 6. The kinetic properties of the somatically recorded postsynaptic current are correlated with the innervated cell surface domain. A significant correlation of rise and decay times for the overall population of unitary IPSCs suggests that electrotonic filtering of distal responses is a major factor for the location and cell type specific differences of unitary IPSCs, but molecular heterogeneity of postsynaptic GABAA receptors may also contribute to the observed kinetic differences. Furthermore, domain specific differences in the short-term plasticity of the postsynaptic response indicate a differentiation of interneurones in activity-dependent responses.

  19. Vibration therapy for Parkinson's disease: Charcot's studies revisited.

    Science.gov (United States)

    Kapur, Sachin S; Stebbins, Glenn T; Goetz, Christopher G

    2012-01-01

    The 19th century neurologist, J-M Charcot, used a vibration chair for treating Parkinson's disease (PD). He documented improvement, but few subsequent studies examined vibration treatment. Using a specialized lounge chair, we conducted a rater blinded, randomized trial of body vibration vs. no vibration in 23 PD patients. The primary outcome measure was change from baseline in the motor section of the MDS-UPDRS. Both vibration and no vibration groups significantly improved after one month of daily treatments. However, there was no significant difference between the two treatment groups, suggesting that non-specific or placebo factors had an effect on PD motor function.

  20. In-situ Vibrational Spectroelectrochemistry

    Science.gov (United States)

    1988-07-15

    also observed. UNDERPOTENTIAL DEPOSITION We have recently studied the low frequency vibrations for layers of lithium on gold electrodes (45,46). In...removal of adatom or adatom clusters on the surface of the SERS active electrode. The stability of the SERS surface to underpotential deposition is... deposition of zinc, while during underpotential deposition of zinc, cyanide adsorption onto both silver and zinc is evident. When a full layer of zinc

  1. Optical fiber grating vibration sensor for vibration monitoring of hydraulic pump

    Science.gov (United States)

    Zhang, Zhengyi; Liu, Chuntong; Li, Hongcai; He, Zhenxin; Zhao, Xiaofeng

    2017-06-01

    In view of the existing electrical vibration monitoring traditional hydraulic pump vibration sensor, the high false alarm rate is susceptible to electromagnetic interference and is not easy to achieve long-term reliable monitoring, based on the design of a beam of the uniform strength structure of the fiber Bragg grating (FBG) vibration sensor. In this paper, based on the analysis of the vibration theory of the equal strength beam, the principle of FBG vibration tuning based on the equal intensity beam is derived. According to the practical application of the project, the structural dimensions of the equal strength beam are determined, and the optimization design of the vibrator is carried out. The finite element analysis of the sensor is carried out by ANSYS, and the first order resonant frequency is 94.739 Hz. The vibration test of the sensor is carried out by using the vibration frequency of 35 Hz and the vibration source of 50 Hz. The time domain and frequency domain analysis results of test data show that the sensor has good dynamic response characteristics, which can realize the accurate monitoring of the vibration frequency and meet the special requirements of vibration monitoring of hydraulic pump under specific environment.

  2. 40 CFR 761.372 - Specific requirements for relatively clean surfaces.

    Science.gov (United States)

    2010-07-01

    ... grimy before a spill, such as glass, automobile surfaces, newly-poured concrete, and desk tops, use the... with a solvent-soaked, disposable absorbent pad such that each 900 cm2 (1 square foot) is wiped for...

  3. Evolution of Specific Surface Area Inside Glass Immersed in Beishan Groundwater

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>The surface area of the fissure inside the glass block is an important parameter influencing the long term behavior of high-level radioactive waste glass in the aqueous media during the deep geological

  4. Plasmodium falciparum parasites expressing pregnancy-specific variant surface antigens adhere strongly to the choriocarcinoma cell line BeWo

    DEFF Research Database (Denmark)

    Haase, Rikke N; Megnekou, Rosette; Lundquist, Maja;

    2006-01-01

    Placenta-sequestering Plasmodium falciparum parasites causing pregnancy-associated malaria express pregnancy-specific variant surface antigens (VSA(PAM)). We report here that VSA(PAM)-expressing patient isolates adhere strongly to the choriocarcinoma cell line BeWo and that the BeWo line can...

  5. Specific Surface versus Electrochemically Active Area of the Carbon/Polypyrrole Capacitor: Correlation of Ion Dynamics Studied by an Electrochemical Quartz Crystal Microbalance with BET Surface.

    Science.gov (United States)

    Mosch, Heike L K S; Akintola, Oluseun; Plass, Winfried; Höppener, Stephanie; Schubert, Ulrich S; Ignaszak, Anna

    2016-05-10

    Carbon/polypyrrole (PPy) composites are promising electrode materials for energy storage applications such as lightweight capacitors. Although these materials are composed of relatively inexpensive components, there is a gap of knowledge regarding the correlation between surface, porosity, ion exchange dynamics, and the interplay of the double layer capacitance and pseudocapacitance. In this work we evaluate the specific surface area analyzed by the BET method and the area accessible for ions using electrochemical quartz-crystal microbalance (EQCM) for SWCNT/PPy and carbon black Vulcan XC72-R/PPy composites. The study revealed that the polymer has significant influence on the pore size of the composites. Although the BET surface is low for the polypyrrole, the electrode mass change and thus the electrochemical area are large for the polymer-containing electrodes. This indicates that multiple redox active centers in the charged polymer chain are good ion scavengers. Also, for the composite electrodes, the effective charge storage occurs at the polypyrrole-carbon junctions, which are easy to design/multiply by a proper carbon-to-polymer weight ratio. The specific BET surface and electrochemically accessible surface area are both important parameters in calculation of the electrode capacitance. SWCNTs/PPy showed the highest capacitances normalized to the BET and electrochemical surface as compared to the polymer-carbon black. TEM imaging revealed very homogeneous distribution of the nanosized polymer particles onto the CNTs, which facilitates the synergistic effect of the double layer capacitance (CNTs) and pseudocapacitance (polymer). The trend in the electrode mass change in correlation with the capacitance suggest additional effects such as a solvent co-insertion into the polymer and the contribution of the charge associated with the redox activity of oxygen-containing functional groups on the carbon surface.

  6. Adsorption of alpha-helical antifreeze peptides on specific ice crystal surface planes

    OpenAIRE

    Knight, C A; Cheng, C C; DeVries, A.L.

    1991-01-01

    The noncolligative peptide and glycopeptide antifreezes found in some cold-water fish act by binding to the ice surface and preventing crystal growth, not by altering the equilibrium freezing point of the water. A simple crystal growth and etching technique allows determination of the crystallographic planes where the binding occurs. In the case of elongated molecules, such as the alpha-helical peptides in this report, it also allows a deduction of the molecular alignment on the ice surface. ...

  7. Cell Surface Properties of Lactococcus lactis Reveal Milk Protein Binding Specifically Evolved in Dairy Isolates

    Directory of Open Access Journals (Sweden)

    Mariya Tarazanova

    2017-09-01

    Full Text Available Surface properties of bacteria are determined by the molecular composition of the cell wall and they are important for interactions of cells with their environment. Well-known examples of bacterial interactions with surfaces are biofilm formation and the fermentation of solid materials like food and feed. Lactococcus lactis is broadly used for the fermentation of cheese and buttermilk and it is primarily isolated from either plant material or the dairy environment. In this study, we characterized surface hydrophobicity, charge, emulsification properties, and the attachment to milk proteins of 55 L. lactis strains in stationary and exponential growth phases. The attachment to milk protein was assessed through a newly developed flow cytometry-based protocol. Besides finding a high degree of biodiversity, phenotype-genotype matching allowed the identification of candidate genes involved in the modification of the cell surface. Overexpression and gene deletion analysis allowed to verify the predictions for three identified proteins that altered surface hydrophobicity and attachment of milk proteins. The data also showed that lactococci isolated from a dairy environment bind higher amounts of milk proteins when compared to plant isolates. It remains to be determined whether the alteration of surface properties also has potential to alter starter culture functionalities.

  8. Cell Surface Properties of Lactococcus lactis Reveal Milk Protein Binding Specifically Evolved in Dairy Isolates.

    Science.gov (United States)

    Tarazanova, Mariya; Huppertz, Thom; Beerthuyzen, Marke; van Schalkwijk, Saskia; Janssen, Patrick; Wels, Michiel; Kok, Jan; Bachmann, Herwig

    2017-01-01

    Surface properties of bacteria are determined by the molecular composition of the cell wall and they are important for interactions of cells with their environment. Well-known examples of bacterial interactions with surfaces are biofilm formation and the fermentation of solid materials like food and feed. Lactococcus lactis is broadly used for the fermentation of cheese and buttermilk and it is primarily isolated from either plant material or the dairy environment. In this study, we characterized surface hydrophobicity, charge, emulsification properties, and the attachment to milk proteins of 55 L. lactis strains in stationary and exponential growth phases. The attachment to milk protein was assessed through a newly developed flow cytometry-based protocol. Besides finding a high degree of biodiversity, phenotype-genotype matching allowed the identification of candidate genes involved in the modification of the cell surface. Overexpression and gene deletion analysis allowed to verify the predictions for three identified proteins that altered surface hydrophobicity and attachment of milk proteins. The data also showed that lactococci isolated from a dairy environment bind higher amounts of milk proteins when compared to plant isolates. It remains to be determined whether the alteration of surface properties also has potential to alter starter culture functionalities.

  9. Do Scaphoideus titanus (Hemiptera: Cicadellidae) nymphs use vibrational communication?

    Science.gov (United States)

    Chuche, Julien; Thiéry, Denis; Mazzoni, Valerio

    2011-07-01

    Small Auchenorrhyncha use substrate-borne vibrations to communicate. Although this behaviour is well known in adult leafhoppers, so far no studies have been published on nymphs. Here we checked the occurrence of vibrational communication in Scaphoideus titanus (Hemiptera: Cicadellidae) nymphs as a possible explanation of their aggregative distributions on host plants. We studied possible vibratory emissions of isolated and grouped nymphs, as well as their behavioural responses to vibration stimuli that simulated presence of conspecifics, to disturbance noise, white noise and predator spiders. None of our synthetic stimuli or pre-recorded substrate vibrations from nymphs elicited specific vibration responses and only those due to grooming or mechanical contacts of the insect with the leaf were recorded. Thus, S. titanus nymphs showed to not use species-specific vibrations neither for intra- nor interspecific communication and also did not produce alarm vibrations when facing potential predators. We conclude that their aggregative behaviour is independent from a vibrational communication.

  10. Vibration analysis of atomising discs

    Energy Technology Data Exchange (ETDEWEB)

    Deng, H; Ouyang, H, E-mail: H.Ouyang@liverpool.ac.u [Department of Engineering, University of Liverpool, Liverpool L69 3GH (United Kingdom)

    2009-08-01

    The centrifugal atomisation of metallic melts using a spinning disc is an important process for powder production and spray deposition. In the manufacturing process the high-temperature melt flows down to the surface of the atomising disc spinning at very high speed. It is observed that there is a hydraulic jump of the melt flow prior to atomisation. In this paper, the dynamic model of the atomising disc as a spinning Kirchhoff plate with this hydraulic jump is established. The flowing melt is modelled as moving mass and weight force in the radial direction. Using a Galerkin method, it is found that the vibration properties of the atomising disc vary with the disc clamping ratio. The amplitude of the vibration is largely raised when the clamping ratio is smaller than the critical jump radius ratio. It is also found that the disc vibration is non-stationary before becoming steady and the amplitude decreases with increasing disc speed.

  11. Surface Plasmon Resonance Studies of the Specific Interactions of Hexamer Peptide Ligands with Human Immunoglobulin G

    Science.gov (United States)

    Islam, Nafisa

    This study characterizes the human immunoglobulin G (IgG) binding on peptides grafted onto self-assembled monolayers (SAMs) and the binding events are studied primarily using surface plasmon resonance (SPR) technology. The dissertation also seeks to determine the optimum surface preparation and surface chemistry approaches for grafting the peptide so that the sensor surfaces demonstrate enhanced selectivity and sensitivity in both laboratory and industrial settings. Peptide covalent grafting was performed on pure and mixed SAMs, the surfaces were characterized and the peptide densities were quantified. Theoretical models were developed and implemented to describe the binding mechanism of IgG with grafted ligands. Protein A was grafted onto SPR sensors and subsequent IgG binding characteristics were compared side-by-side to those of peptide-IgG binding. It was found that Protein A-based sensors showed much higher selectivities and higher binding capacities than their peptides based counterparts. Oligo(ethylene glycol) alkanethiol-based pure and mixed SAMs were grafted with peptides in order to determine the optimal surface among these, for enhanced selectivity. Among the mixed SAMs formed from different precursor solutions, a surface with peptides grafted onto mixed SAMs formulated from 10% amine-terminated/90% hydroxyl-terminated alkanethiols showed optimum selectivity. Studies were carried out to increase the peptide density via grafting of branched amines onto surfaces. The branched amine-based peptide surfaces displayed improved sensitivities and similar selectivities to the surfaces based on un-branched amine termini. Kinetic analyses were carried out to determine the characteristics of IgG binding to ligands grafted in the abovementioned methods. Kinetic analysis of binding indicated that Protein A-IgG interactions have concentrationdependent affinity properties that could be attributed to the allosteric effects of the interaction. The lack of tertiary

  12. Using Surface Treatment Specification Databases to Anticipate and Accelerate Response to Regulatory Changes

    Science.gov (United States)

    2012-08-28

    Substance declarations, MSDS data, specifications 3. Tools REPORT Substances in article, Article 33 ... INTEGRATE, ACCESS from: PLM , CAD, ERP...specifications, materials & processes for regulatory impact & obsolescence risk Use existing infrastructure (e.g. CAD, PLM ) to deploy strategy into engineers

  13. Electrospun anatase-phase TiO2 nanofibers with different morphological structures and specific surface areas.

    Science.gov (United States)

    He, Guangfei; Cai, Yibing; Zhao, Yong; Wang, Xiaoxu; Lai, Chuilin; Xi, Min; Zhu, Zhengtao; Fong, Hao

    2013-05-15

    Electrospun anatase-phase TiO2 nanofibers with desired morphological structure and relatively high specific surface area are expected to outperform other nanostructures (e.g., powder and film) of TiO2 for various applications (particularly dye-sensitized solar cell and photo-catalysis). In this study, systematic investigations were carried out to prepare and characterize electrospun anatase-phase TiO2 nanofibers with different morphological structures (e.g., solid, hollow/tubular, and porous) and specific surface areas. The TiO2 nanofibers were generally prepared via electrospinning of precursor nanofibers followed by pyrolysis at 500°C. For making hollow/tubular TiO2 nanofibers, the technique of co-axial electrospinning was utilized; while for making porous TiO2 nanofibers, the etching treatment in NaOH aqueous solution was adopted. The results indicated that the hollow/tubular TiO2 nanofibers (with diameters of ~300-500 nm and wall-thickness in the range from tens of nanometers to ~200 nm) had the BET specific surface area of ~27.3 m(2)/g, which was approximately twice as that of the solid TiO2 nanofibers (~15.2 m(2)/g) with diameters of ~200-300 nm and lengths of at least tens of microns. Porous TiO2 nanofibers made from the precursor of Al2O3/TiO2 composite nanofibers had the BET specific surface area of ~106.5 m(2)/g, whereas porous TiO2 nanofibers made from the precursor of ZnO/TiO2 composite nanofibers had the highest BET specific surface area of ~148.6 m(2)/g.

  14. SU-E-T-04: 3D Printed Patient-Specific Surface Mould Applicators for Brachytherapy Treatment of Superficial Lesions

    Energy Technology Data Exchange (ETDEWEB)

    Cumming, I; Lasso, A; Rankin, A; Fichtinger, G [Laboratory for Percutaneous Surgery, School of Computing, Queen' s University, Kingston, Ontario (Canada); Joshi, C P; Falkson, C; Schreiner, L John [CCSEO, Kingston General Hospital and Department of Oncology, Queen' s University, Kingston, Ontario (Canada)

    2014-06-01

    Purpose: Evaluate the feasibility of constructing 3D-printed patient-specific surface mould applicators for HDR brachytherapy treatment of superficial lesions. Methods: We propose using computer-aided design software to create 3D printed surface mould applicators for brachytherapy. A mould generation module was developed in the open-source 3D Slicer ( http://www.slicer.org ) medical image analysis platform. The system extracts the skin surface from CT images, and generates smooth catheter paths over the region of interest based on user-defined start and end points at a specified stand-off distance from the skin surface. The catheter paths are radially extended to create catheter channels that are sufficiently wide to ensure smooth insertion of catheters for a safe source travel. An outer mould surface is generated to encompass the channels. The mould is also equipped with fiducial markers to ensure its reproducible placement. A surface mould applicator with eight parallel catheter channels of 4mm diameters was fabricated for the nose region of a head phantom; flexible plastic catheters of 2mm diameter were threaded through these channels maintaining 10mm catheter separations and a 5mm stand-off distance from the skin surface. The apparatus yielded 3mm thickness of mould material between channels and the skin. The mould design was exported as a stereolithography file to a Dimension SST1200es 3D printer and printed using ABS Plus plastic material. Results: The applicator closely matched its design and was found to be sufficiently rigid without deformation during repeated application on the head phantom. Catheters were easily threaded into channels carved along catheter paths. Further tests are required to evaluate feasibility of channel diameters smaller than 4mm. Conclusion: Construction of 3D-printed mould applicators show promise for use in patient specific brachytherapy of superficial lesions. Further evaluation of 3D printing techniques and materials is required

  15. Unexpected red shift of C-H vibrational band of Methyl benzoate

    CERN Document Server

    Maiti, Kiran Sankar; Scheurer, Christoph

    2016-01-01

    The C-H vibrational bands become more and more important in the structural determination of biological molecules with the development of CARS microscopy and 2DIR spectroscopy. Due to the congested pattern, near degeneracy, and strong anharmonicity of the C-H stretch vibrations, assignment of the C-H vibrational bands are often misleading. Anharmonic vibrational spectra calculation with multidimensional potential energy surface interprets the C-H vibrational spectra more accurately. In this article we have presented the importance of multidimensional potential energy surface in anharmonic vibrational spectra calculation and discuss the unexpected red shift of C-H vibrational band of Methyl benzoate.

  16. Interfacial instabilities in vibrated fluids

    Science.gov (United States)

    Porter, Jeff; Laverón-Simavilla, Ana; Tinao Perez-Miravete, Ignacio; Fernandez Fraile, Jose Javier

    2016-07-01

    Vibrations induce a range of different interfacial phenomena in fluid systems depending on the frequency and orientation of the forcing. With gravity, (large) interfaces are approximately flat and there is a qualitative difference between vertical and horizontal forcing. Sufficient vertical forcing produces subharmonic standing waves (Faraday waves) that extend over the whole interface. Horizontal forcing can excite both localized and extended interfacial phenomena. The vibrating solid boundaries act as wavemakers to excite traveling waves (or sloshing modes at low frequencies) but they also drive evanescent bulk modes whose oscillatory pressure gradient can parametrically excite subharmonic surface waves like cross-waves. Depending on the magnitude of the damping and the aspect ratio of the container, these locally generated surfaces waves may interact in the interior resulting in temporal modulation and other complex dynamics. In the case where the interface separates two fluids of different density in, for example, a rectangular container, the mass transfer due to vertical motion near the endwalls requires a counterflow in the interior region that can lead to a Kelvin-Helmholtz type instability and a ``frozen wave" pattern. In microgravity, the dominance of surface forces favors non-flat equilibrium configurations and the distinction between vertical and horizontal applied forcing can be lost. Hysteresis and multiplicity of solutions are more common, especially in non-wetting systems where disconnected (partial) volumes of fluid can be established. Furthermore, the vibrational field contributes a dynamic pressure term that competes with surface tension to select the (time averaged) shape of the surface. These new (quasi-static) surface configurations, known as vibroequilibria, can differ substantially from the hydrostatic state. There is a tendency for the interface to orient perpendicular to the vibrational axis and, in some cases, a bulge or cavity is induced

  17. Specific features of heat transfer on the external surface of smoke stacks blown by wind

    Science.gov (United States)

    Maneev, A. P.; Terekhov, V. I.

    2015-03-01

    Results of a full-scale experiment on studying heat transfer on the surface of a reinforced-concrete smoke stack blown by wind at the value of Reynolds number Re = 1.05 × 107 are presented. Comparison of the experimental results with the experimental data obtained previously by other researchers under laboratory conditions at Re cylinder in a transcritical streamlining mode. The data obtained in the present study open the possibility to estimate the average values of heat transfer coefficient on the surface of smoke stacks in a flow of atmospheric air at 4 × 106 < Re < 107.

  18. Production, Delivery and Application of Vibration Energy in Healthcare

    Energy Technology Data Exchange (ETDEWEB)

    Abundo, Paolo; Trombetta, Chiara [Medical Engineering Service, Fondazione Policlinico Tor Vergata, Viale Oxford 81 - Roma (Italy); Foti, Calogero; Rosato, Nicola, E-mail: paolo.abundo@ptvonline.it [Tor Vergata University, Physical and Rehabilitation Medicine, Public Health Department, Via Montpellier 1 - Roma (Italy)

    2011-02-01

    In Rehabilitation Medicine therapeutic application of vibration energy in specific clinical treatments and in sport rehabilitation is being affirmed more and more.Vibration exposure can have positive or negative effects on the human body depending on the features and time of the characterizing wave. The human body is constantly subjected to different kinds of vibrations, inducing bones and muscles to actively modify their structure and metabolism in order to fulfill the required functions. Like every other machine, the body supports only certain vibration energy levels over which long term impairments can be recognized. As shown in literature anyway, short periods of vibration exposure and specific frequency values can determine positive adjustments.

  19. Enhanced Activity and Altered Specificity of Phospholipase A2 by Deletion of a Surface Loop

    NARCIS (Netherlands)

    Kuipers, Oscar P.; Thunnissen, Marjolein M.G.M.; Geus, Pieter de; Dijkstra, Bauke W.; Drenth, Jan; Verheij, Hubertus M.; Haas, Gerard H. de

    1989-01-01

    Protein engineering and x-ray crystallography have been used to study the role of a surface loop that is present in pancreatic phospholipases but is absent in snake venom phospholipases. Removal of residues 62 to 66 from porcine pancreatic phospholipase A2 does not change the binding constant for mi

  20. Improvement of the Specificity of Surface Plasmon Resonance with BSA-modified Chip

    Institute of Scientific and Technical Information of China (English)

    Li Hua CHEN

    2006-01-01

    A chip was modified with bovine serum albumin (BSA), then interaction between glutathione (GSH) immobilized on the top of BSA and glutathione-S-transferase (GST) was examined, using surface plasmon resonance (SPR). The SPR results showed that BSA-modified chip was effective not only in binding the target proteins but also in suppressing the nonspecific binding (NSB) of proteins.

  1. Enhanced Activity and Altered Specificity of Phospholipase A2 by Deletion of a Surface Loop

    NARCIS (Netherlands)

    Kuipers, Oscar P.; Thunnissen, Marjolein M.G.M.; Geus, Pieter de; Dijkstra, Bauke W.; Drenth, Jan; Verheij, Hubertus M.; Haas, Gerard H. de

    1989-01-01

    Protein engineering and x-ray crystallography have been used to study the role of a surface loop that is present in pancreatic phospholipases but is absent in snake venom phospholipases. Removal of residues 62 to 66 from porcine pancreatic phospholipase A2 does not change the binding constant for mi

  2. Surface charge-specific interactions between polymer nanoparticles and ABC transporters in Caco-2 cells

    NARCIS (Netherlands)

    Bhattacharjee, S.; Opstal, van E.J.; Alink, G.M.; Marcelis, A.T.M.; Zuilhof, H.; Rietjens, I.M.C.M.

    2013-01-01

    The surface charge-dependent transport of polymeric nanoparticles (PNPs) across Caco-2 monolayers grown on transwell culture systems as an in vitro model for intestinal transport was tested. The transport of well-characterized, monodisperse, and fluorescent tri-block copolymer nanoparticles (TCNPs/s

  3. Ionic profiles close to dielectric discontinuities: Specific ion-surface interactions

    CERN Document Server

    Markovich, Tomer; Orland, Henri

    2016-01-01

    We study, by incorporating short-range ion-surface interactions, ionic profiles of electrolyte solutions close to a non-charged interface between two dielectric media. In order to account for important correlation effects close to the interface, the ionic profiles are calculated beyond mean-field theory, using the loop expansion of the free energy. We show how it is possible to overcome the well-known deficiency of the regular loop expansion close to the dielectric jump, and treat the non-linear boundary conditions within the framework of field theory. The ionic profiles are obtained analytically to one-loop order in the free energy, and their dependence on different ion-surface interactions is investigated. The Gibbs adsorption isotherm, as well as the ionic profiles are used to calculate the surface tension, in agreement with the reverse Hofmeister series. Consequently, from the experimentally-measured surface tension, one can extract a single adhesivity parameter, which can be used within our model to quan...

  4. Molecular N-2 chemisorption-specific adsorption on step defect sites on Pt surfaces

    DEFF Research Database (Denmark)

    Tripa, C. Emil; Zubkov, T.S.; Yates, John T.

    1999-01-01

    Infrared reflection-absorption spectroscopy and density functional theory, within the generalized gradient approximation, were used to investigate both experimentally and theoretically N-2 chemisorption on stepped and smooth Pt surfaces. N-2 chemisorption was observed to occur only on the edge...

  5. Specificity for field enumeration of Escherichia coli in tropical surface waters

    DEFF Research Database (Denmark)

    Jensen, Peter Kjær Mackie; Aalbaek, B; Aslam, R

    2001-01-01

    In remote rural areas in developing countries, bacteriological monitoring often depends on the use of commercial field media. This paper evaluates a commercial field medium used for the enumeration of Escherichia coli in different surface waters under primitive field conditions in rural Pakistan....

  6. Surface charge-specific cytotoxicity and cellular uptake of tri-block copolymer nanoparticles

    NARCIS (Netherlands)

    Bhattacharjee, S.; Ershov, D.S.; Gucht, van der J.; Alink, G.M.; Rietjens, I.; Zuilhof, H.; Marcelis, A.T.M.

    2013-01-01

    A series of monodisperse (45 ± 5 nm) fluorescent nanoparticles from tri-block copolymers (polymeric nanoparticles (PNPs)) bearing different surface charges were synthesised and investigated for cytotoxicity in NR8383 and Caco-2 cells. The positive PNPs were more cytotoxic and induced a higher intrac

  7. Artificial neural network approach for estimation of surface specific humidity and air temperature using Multifrequency Scanning Microwave Radiometer

    Indian Academy of Sciences (India)

    Randhir Singh; B G Vasudevan; P K Pal; P C Joshi

    2004-03-01

    Microwave sensor MSMR (Multifrequency Scanning Microwave Radiometer) data onboard Oceansat-1 was used for retrieval of monthly averages of near surface specific humidity (a) and air temperature (a) by means of Artificial Neural Network (ANN). The MSMR measures the microwave radiances in 8 channels at frequencies of 6.6, 10.7, 18 and 21 GHz for both vertical and horizontal polarizations. The artificial neural networks (ANN) technique is employed to find the transfer function relating the input MSMR observed brightness temperatures and output (a and a) parameters. Input data consist of nearly 28 months (June 1999 — September 2001) of monthly averages of MSMR observed brightness temperature and surface marine observations of a and a from Comprehensive Ocean- Atmosphere Data Set (COADS). The performance of the algorithm is assessed with independent surface marine observations. The results indicate that the combination of MSMR observed brightness temperatures as input parameters provides reasonable estimates of monthly averaged surface parameters. The global root mean square (rms) differences are 1.0°C and 1.1 g kg−1 for air temperature and surface specific humidity respectively.

  8. Vibrational Microspectroscopy for Cancer Screening

    Directory of Open Access Journals (Sweden)

    Fiona M. Lyng

    2015-02-01

    Full Text Available Vibrational spectroscopy analyses vibrations within a molecule and can be used to characterise a molecular structure. Raman spectroscopy is one of the vibrational spectroscopic techniques, in which incident radiation is used to induce vibrations in the molecules of a sample, and the scattered radiation may be used to characterise the sample in a rapid and non-destructive manner. Infrared (IR spectroscopy is a complementary vibrational spectroscopic technique based on the absorption of IR radiation by the sample. Molecules absorb specific frequencies of the incident light which are characteristic of their structure. IR and Raman spectroscopy are sensitive to subtle biochemical changes occurring at the molecular level allowing spectral variations corresponding to disease onset to be detected. Over the past 15 years, there have been numerous reports demonstrating the potential of IR and Raman spectroscopy together with multivariate statistical analysis techniques for the detection of a variety of cancers including, breast, lung, brain, colon, oral, oesophageal, prostate and cervical cancer. This paper discusses the recent advances and the future perspectives in relation to cancer screening applications, focussing on cervical and oral cancer.

  9. Analysis of Vibration Specific and Natural Frequency of Axial-flow Compressor Blades%轴流式压缩机叶片振动特性及固有频率分析

    Institute of Scientific and Technical Information of China (English)

    白静

    2013-01-01

    The kinetic characteristics of blades of axial-flow compressor were researched by taking blades of axial-flow compressor as subjects. The static frequency, the dynamic frequency and vibration modes were calculated by the mode analysis of the blades. The difference between the dynamic frequency and the static frequency was small under each rotational speed. Because the pre-stress imposed by the centrifugal force was distributed in the groove, the centrifugal force has little influence on the vibration specific of the blades. The Campbell diagram which described the dynamic frequency under the rotational speed of 1000~3000 r/min is drew. Through an analysis of the Campbell diagram and the calculation of resonance safety ratio, it was found that there are two resonant peaks and frequency must be adjusted.%以轴流压缩机动叶片为研究对象,分析了轴流式压缩机叶片的动态特性.对叶片进行模态分析,计算得到其静频值、动频值及其相应振型.发现叶片在各个转速下的动频值与静频值相差很小,说明离心初应力对叶片的振动特性影响很小,这是因为离心力产生的预应力仅仅分布在叶根榫槽处.并将模态计算得到的转速1 000~3 000 r/min的动频绘制成Campbell图,通过对Campbell图进行分析及共振安全率的计算发现,叶片存在2个共振点,必须对其进行调频.

  10. Two-dimensional optical coherence vibration tomography for low-frequency vibration measurement and response-only modal analysis

    Science.gov (United States)

    Zhong, Jianfeng; Zhong, Shuncong; Zhang, Qiukun

    2016-10-01

    A high-speed camera-based two-dimensional optical coherence vibration tomography (2DOCVT) system with a subnanometre displacement resolution was developed and employed for low-frequency vibration measurement and modal analysis. Experimental results demonstrated the ability of low-frequency absolute displacement measurement of structural line vibrations without scanning. Three-dimensional (3D) surface displacement of a vibrating structure could also be obtained using the developed 2DOCVT by scanning the structure. The scanning 2DOCVT system acted like a 3D optical coherence vibration tomography system. The developed 2DOCVT system could capture structural modal parameters without vibration excitation input information, and therefore, it is a response-only method. The 2DOCVT could be recommended in the application of low-frequency vibration measurement and modal analysis of beam and plate structures, especially when the vibration amplitude is at nanometre or micrometre scale.

  11. Initiation of blood coagulation - Evaluating the relevance of specific surface functionalities using self assembled monolayers

    OpenAIRE

    Fischer, Marion

    2010-01-01

    The surface of biomaterials can induce contacting blood to coagulate, similar to the response initiated by injured blood vessels to control blood loss. This poses a challenge to the use of biomaterials as the resulting coagulation can impair the performance of hemocompatible devices such as catheters, vascular stents and various extracorporeal tubings [1], what can moreover cause severe host reactions like embolism and infarction. Biomaterial induced coagulation processes limit the therape...

  12. Adsorption of alpha-helical antifreeze peptides on specific ice crystal surface planes.

    Science.gov (United States)

    Knight, C A; Cheng, C C; DeVries, A L

    1991-02-01

    The noncolligative peptide and glycopeptide antifreezes found in some cold-water fish act by binding to the ice surface and preventing crystal growth, not by altering the equilibrium freezing point of the water. A simple crystal growth and etching technique allows determination of the crystallographic planes where the binding occurs. In the case of elongated molecules, such as the alpha-helical peptides in this report, it also allows a deduction of the molecular alignment on the ice surface. The structurally similar antifreeze peptides from winter flounder (Pseudopleuronectes americanus) and Alaskan plaice (Pleuronectes quadritaberulatus) adsorb onto the (2021) pyramidal planes of ice, whereas the sculpin (Myoxocephalus scorpius) peptide adsorbs on (2110), the secondary prism planes. All three are probably aligned along (0112). These antifreeze peptides have 11-amino acid sequence repeats ending with a polar residue, and each repeat constitutes a distance of 16.5 A along the helix, which nearly matches the 16.7 A repeat spacing along (0112) in ice. This structural match is undoubtedly important, but the mechanism of binding is not yet clear. The suggested mechanism of growth inhibition operates through the influence of local surface curvature upon melting point and results in complete inhibition of the crystal growth even though individual antifreeze molecules bind at only one interface orientation.

  13. Portable vibration exciter

    Science.gov (United States)

    Beecher, L. C.; Williams, F. T.

    1970-01-01

    Gas-driven vibration exciter produces a sinusoidal excitation function controllable in frequency and in amplitude. It allows direct vibration testing of components under normal loads, removing the possibility of component damage due to high static pressure.

  14. Control System Damps Vibrations

    Science.gov (United States)

    Kopf, E. H., Jr.; Brown, T. K.; Marsh, E. L.

    1983-01-01

    New control system damps vibrations in rotating equipment with help of phase-locked-loop techniques. Vibrational modes are controlled by applying suitable currents to drive motor. Control signals are derived from sensors mounted on equipment.

  15. 7075-T6铝合金单向超声振动车削表面质量及形貌特征%Research on unidirectional ultrasonic vibrations turning 7075 -T6 aluminum alloy surface quality and morphology

    Institute of Scientific and Technical Information of China (English)

    栾晓明; 胡斌梁; 周知进

    2014-01-01

    7075 -T6 aluminum alloy specimens were tested for machining experiments by using ordinary cutting (CT ) and the vibration cutting (UVC ) processing methods, to analyze the influence of cutting parameters on the work piece surface roughness.Experimental results show that:In the same amount of feed and depth of cut,speed with the turning changed,the surface roughness of ordinary cutting reduced first decreases and then increases again,but with the speed increased into the high -speed,the surface roughness become stable;The surface roughness uptrend with the feed rate increased of ultrasonic vibrations hard turning and ordinary hard cutting;In the same cutting speed and feed rate,with cutting depth increased ,7075 Aluminum ordinary hard cutting surface roughness increased,but the ultrasonic vibration cutting surface roughness first decrease and then increase.Through the analysis of experimental data obtained and the observations of the microscopic morphology of the machined surface after turning,the advantage of ultrasonic vibration machining in difficult materials processing is confirmed.%对7075-T6铝合金试件采用普通切削(CT)和振动切削(UVC)加工方法进行了加工实验,分析了2种切削加工方法在不同参数下对铝合金试件加工表面粗糙度的影响。试验研究结果表明:在相同的进给量和切削深度情况下,随着车削速度的变化,普通切削获得的加工表面粗糙度先减小后增大再减小,但随着转速的增大进入高速切削后,工件表面粗糙度值逐渐趋于稳定;随着进给量的增加超声振动硬车削与普通硬切削加工表面粗糙度都呈上升趋势,超声振动切削表面粗糙度较小;在切削速度、进给量相同的条件下,普通硬质切削7075铝合金加工表面粗糙度随着切削深度的增加而增加,而超声振动切削7075铝合金加工表面粗糙度随着切削深度的增加先减小后增加。通过对获得实验数

  16. A protein allergen microarray detects specific IgE to pollen surface, cytoplasmic, and commercial allergen extracts.

    Directory of Open Access Journals (Sweden)

    Katinka A Vigh-Conrad

    Full Text Available Current diagnostics for allergies, such as skin prick and radioallergosorbent tests, do not allow for inexpensive, high-throughput screening of patients. Additionally, extracts used in these methods are made from washed pollen that lacks pollen surface materials that may contain allergens.We sought to develop a high-throughput assay to rapidly measure allergen-specific IgE in sera and to explore the relative allergenicity of different pollen fractions (i.e. surface, cytoplasmic, commercial extracts. To do this, we generated a protein microarray containing surface, cytoplasmic, and commercial extracts from 22 pollen species, commercial extracts from nine non-pollen allergens, and five recombinant allergenic proteins. Pollen surface and cytoplasmic fractions were prepared by extraction into organic solvents and aqueous buffers, respectively. Arrays were incubated with <25 uL of serum from 176 individuals and bound IgE was detected by indirect immunofluorescence, providing a high-throughput measurement of IgE. We demonstrated that the allergen microarray is a reproducible method to measure allergen-specific IgE in small amounts of sera. Using this tool, we demonstrated that specific IgE clusters according to the phylogeny of the allergen source. We also showed that the pollen surface, which has been largely overlooked in the past, contained potent allergens. Although, as a class, cytoplasmic fractions obtained by our pulverization/precipitation method were comparable to commercial extracts, many individual allergens showed significant differences.These results support the hypothesis that protein microarray technology is a useful tool for both research and in the clinic. It could provide a more efficient and less painful alternative to traditionally used skin prick tests, making it economically feasible to compare allergen sensitivity of different populations, monitor individual responses over time, and facilitate genetic studies on pollen allergy.

  17. Granular avalanches down inclined and vibrated planes

    Science.gov (United States)

    Gaudel, Naïma; Kiesgen de Richter, Sébastien; Louvet, Nicolas; Jenny, Mathieu; Skali-Lami, Salaheddine

    2016-09-01

    In this article, we study granular avalanches when external mechanical vibrations are applied. We identify conditions of flow arrest and compare with the ones classically observed for nonvibrating granular flows down inclines [Phys. Fluids 11, 542 (1999), 10.1063/1.869928]. We propose an empirical law to describe the thickness of the deposits with the inclination angle and the vibration intensity. The link between the surface velocity and the depth of the flow highlights a competition between gravity and vibrations induced flows. We identify two distinct regimes: (a) gravity-driven flows at large angles where vibrations do not modify dynamical properties but the deposits (scaling laws in this regime are in agreement with the literature for nonvibrating granular flows) and (b) vibrations-driven flows at small angles where no flow is possible without applied vibrations (in this last regime, the flow behavior can be properly described by a vibration induced activated process). We show, in this study, that granular flows down inclined planes can be finely tuned by external mechanical vibrations.

  18. Superhydrophobic Surface Enhanced Raman Scattering Sensing using Janus Particle Arrays Realized by Site-Specific Electrochemical Growth

    OpenAIRE

    Yang, Shikuan; Hricko, Patrick John; Huang, Po-Hsun; Li, Sixing; Zhao, Yanhui; Xie, Yuliang; Guo, Feng; Wang, Lin; Huang, Tony Jun

    2013-01-01

    Site-specific electrochemical deposition is used to prepare polystyrene (PS)-Ag Janus particle arrays with superhydrophobic properties. The analyte molecules can be significantly enriched using the superhydrophobic property of the PS-Ag Janus particle array before SERS detections, enabling an extremely sensitive detection of molecules in a highly diluted solution (e.g., femtomolar level). This superhydrophobic surface enhanced Raman scattering sensing concept described here is of critical sig...

  19. The Non-Specific Binding of Fluorescent-Labeled MiRNAs on Cell Surface by Hydrophobic Interaction.

    Directory of Open Access Journals (Sweden)

    Ting Lu

    Full Text Available MicroRNAs are small noncoding RNAs about 22 nt long that play key roles in almost all biological processes and diseases. The fluorescent labeling and lipofection are two common methods for changing the levels and locating the position of cellular miRNAs. Despite many studies about the mechanism of DNA/RNA lipofection, little is known about the characteristics, mechanisms and specificity of lipofection of fluorescent-labeled miRNAs.Therefore, miRNAs labeled with different fluorescent dyes were transfected into adherent and suspension cells using lipofection reagent. Then, the non-specific binding and its mechanism were investigated by flow cytometer and laser confocal microscopy. The results showed that miRNAs labeled with Cy5 (cyanine fluorescent dye could firmly bind to the surface of adherent cells (Hela and suspended cells (K562 even without lipofection reagent. The binding of miRNAs labeled with FAM (carboxyl fluorescein to K562 cells was obvious, but it was not significant in Hela cells. After lipofectamine reagent was added, most of the fluorescently labeled miRNAs binding to the surface of Hela cells were transfected into intra-cell because of the high transfection efficiency, however, most of them were still binding to the surface of K562 cells. Moreover, the high-salt buffer which could destroy the electrostatic interactions did not affect the above-mentioned non-specific binding, but the organic solvent which could destroy the hydrophobic interactions eliminated it.These results implied that the fluorescent-labeled miRNAs could non-specifically bind to the cell surface by hydrophobic interaction. It would lead to significant errors in the estimation of transfection efficiency only according to the cellular fluorescence intensity. Therefore, other methods to evaluate the transfection efficiency and more appropriate fluorescent dyes should be used according to the cell types for the accuracy of results.

  20. Multidimensional Time-Resolved Spectroscopy of Vibrational Coherence in Biopolyenes

    Science.gov (United States)

    Buckup, Tiago; Motzkus, Marcus

    2014-04-01

    Multidimensional femtosecond time-resolved vibrational coherence spectroscopy allows one to investigate the evolution of vibrational coherence in electronic excited states. Methods such as pump-degenerate four-wave mixing and pump-impulsive vibrational spectroscopy combine an initial ultrashort laser pulse with a nonlinear probing sequence to reinduce vibrational coherence exclusively in the excited states. By carefully exploiting specific electronic resonances, one can detect vibrational coherence from 0 cm-1 to over 2,000 cm-1 and map its evolution. This review focuses on the observation and mapping of high-frequency vibrational coherence for all-trans biological polyenes such as β-carotene, lycopene, retinal, and retinal Schiff base. We discuss the role of molecular symmetry in vibrational coherence activity in the S1 electronic state and the interplay of coupling between electronic states and vibrational coherence.

  1. Multidimensional time-resolved spectroscopy of vibrational coherence in biopolyenes.

    Science.gov (United States)

    Buckup, Tiago; Motzkus, Marcus

    2014-01-01

    Multidimensional femtosecond time-resolved vibrational coherence spectroscopy allows one to investigate the evolution of vibrational coherence in electronic excited states. Methods such as pump-degenerate four-wave mixing and pump-impulsive vibrational spectroscopy combine an initial ultrashort laser pulse with a nonlinear probing sequence to reinduce vibrational coherence exclusively in the excited states. By carefully exploiting specific electronic resonances, one can detect vibrational coherence from 0 cm(-1) to over 2,000 cm(-1) and map its evolution. This review focuses on the observation and mapping of high-frequency vibrational coherence for all-trans biological polyenes such as β-carotene, lycopene, retinal, and retinal Schiff base. We discuss the role of molecular symmetry in vibrational coherence activity in the S1 electronic state and the interplay of coupling between electronic states and vibrational coherence.

  2. DOWNHOLE VIBRATION MONITORING & CONTROL SYSTEM

    Energy Technology Data Exchange (ETDEWEB)

    Martin E. Cobern

    2004-08-31

    The deep hard rock drilling environment induces severe vibrations into the drillstring, which can cause reduced rates of penetration (ROP) and premature failure of the equipment. The only current means of controlling vibration under varying conditions is to change either the rotary speed or the weight-on-bit (WOB). These changes often reduce drilling efficiency. Conventional shock subs are useful in some situations, but often exacerbate the problems. The objective of this project is development of a unique system to monitor and control drilling vibrations in a ''smart'' drilling system. This system has two primary elements: (1) The first is an active vibration damper (AVD) to minimize harmful axial, lateral and torsional vibrations. The hardness of this damper will be continuously adjusted using a robust, fast-acting and reliable unique technology. (2) The second is a real-time system to monitor drillstring vibration, and related parameters. This monitor adjusts the damper according to local conditions. In some configurations, it may also send diagnostic information to the surface via real-time telemetry. The AVD is implemented in a configuration using magnetorheological (MR) fluid. By applying a current to the magnetic coils in the damper, the viscosity of the fluid can be changed rapidly, thereby altering the damping coefficient in response to the measured motion of the tool. Phase I of this program entailed modeling and design of the necessary subsystems and design, manufacture and test of a full laboratory prototype. Phase I of the project was completed by the revised end date of May 31, 2004. The objectives of this phase were met, and all prerequisites for Phase II have been completed.

  3. DOWNHOLE VIBRATION MONITORING & CONTROL SYSTEM

    Energy Technology Data Exchange (ETDEWEB)

    Martin E. Cobern

    2004-08-31

    The deep hard rock drilling environment induces severe vibrations into the drillstring, which can cause reduced rates of penetration (ROP) and premature failure of the equipment. The only current means of controlling vibration under varying conditions is to change either the rotary speed or the weight-on-bit (WOB). These changes often reduce drilling efficiency. Conventional shock subs are useful in some situations, but often exacerbate the problems. The objective of this project is development of a unique system to monitor and control drilling vibrations in a ''smart'' drilling system. This system has two primary elements: (1) The first is an active vibration damper (AVD) to minimize harmful axial, lateral and torsional vibrations. The hardness of this damper will be continuously adjusted using a robust, fast-acting and reliable unique technology. (2) The second is a real-time system to monitor drillstring vibration, and related parameters. This monitor adjusts the damper according to local conditions. In some configurations, it may also send diagnostic information to the surface via real-time telemetry. The AVD is implemented in a configuration using magnetorheological (MR) fluid. By applying a current to the magnetic coils in the damper, the viscosity of the fluid can be changed rapidly, thereby altering the damping coefficient in response to the measured motion of the tool. Phase I of this program entailed modeling and design of the necessary subsystems and design, manufacture and test of a full laboratory prototype. Phase I of the project was completed by the revised end date of May 31, 2004. The objectives of this phase were met, and all prerequisites for Phase II have been completed.

  4. Vibration in metal and non-metal incubators.

    Science.gov (United States)

    Youngblut, J M; Lewandowski, W; Casper, G R; Youngblut, W R

    1994-01-01

    The purpose of this study was to determine the amount of vibration transmitted to the surface of an incubator mattress. Empty incubators with metal (n = 12) and non-metal (n = 12) bases were monitored for vibration levels when the incubators were turned "off" and when they were turned "on." High levels of low-frequency vibration were detected in both types of incubators in both conditions. The metal incubators transmitted significantly less vibration to the mattress than did the non-metal incubators at several frequencies in the "off," the "on," and the "adjusted" conditions. These results suggest that infants experience significant whole-body vibration while lying in incubators.

  5. Optimization of operating variables for production of ultra-fine talc in a stirred mill. Specific surface area investigations

    Directory of Open Access Journals (Sweden)

    Toraman Oner Yusuf

    2016-01-01

    Full Text Available Due to its properties such as chemical inertness, softness, whiteness, high thermal conductivity, low electrical conductivity and adsorption properties talc has wide industrial applications in paper, cosmetics, paints, polymer, ceramics, refractory materials and pharmaceutical. The demand for ultra-fine talc is emerging which drives the mineral industry to produce value added products. In this study, it was investigated how certain grinding parameters such as mill speed, ball filling ratio, powder filling ratio and grinding time of dry stirred mill affect grindability of talc ore (d97=127 μm. A series of laboratory experiments using a 24 full factorial design was conducted to determine the optimal operational parameters of a stirred mill in order to minimize the specific surface area. The main and interaction effects on the volume specific surface area (SV, m2.cm−3 of the ground product were evaluated using the Yates analysis. Under the optimal conditions at the stirrer speed of 600 rpm, grinding time of 20 min, sample mass of 5% and ball ratio of 70%, the resulting talc powder had larger volume specific surface area (i.e., 3.48 m2.cm−3 than the starting material (i.e., 1.84 m2.cm−3.

  6. Au/HClO4 interface: Influence of preparation technique of the electrode surface and specific anion adsorption

    Directory of Open Access Journals (Sweden)

    A HAMMADI

    2007-12-01

    Full Text Available We present electrochemical impedance spectra made on gold alloy containing 30% silver electrodes of various roughnesses in aqueous perchlorate acid solution as supporting electrolyte in the absence and the presence of mM of specifically adsorbed halide ions X (X = Br-, Cl-, I-, at potentials where the dominant electrode process is the adsorption of the above anions. Efforts were mainly concentrated on the importance of surface preparation technique of the electrode and its influence on impedance spectra. Atomic scale inhomogeneities are introduced by mechanical treatment and can be decreased by annealing. Due to the annealing the double layer behaves as (almost an ideal capacitance in the absence of specific adsorption though surface roughness remains the same. A study of the related impedance behaviour in the presence of adsorbates even at very low concentrations (10-4M, revealed capacitance dispersion increasing with the extent of specific anion adsorption at the gold/silver surface.

  7. Synoptic relationships quantified between surface Chlorophyll-a and diagnostic pigments specific to phytoplankton functional types

    Science.gov (United States)

    Hirata, T.; Hardman-Mountford, N. J.; Brewin, R. J. W.; Aiken, J.; Barlow, R.; Suzuki, K.; Isada, T.; Howell, E.; Hashioka, T.; Noguchi-Aita, M.; Yamanaka, Y.

    2010-09-01

    Error-quantified, synoptic-scale relationships between chlorophyll-a (Chla) and phytoplankton pigment groups at the sea surface are presented. A total of nine pigment groups were considered to represent nine phytoplankton functional types (PFTs) including microplankton, nanoplankton, picoplankton, diatoms, dinoflagellates, green algae, picoeukaryotes, prokaryotes and Prochlorococcus sp. The observed relationships between Chla and pigment groups were well-defined at the global scale to show that Chla can be used as an index of not only phytoplankton abundance but also community structure; large (micro) phytoplankton monotonically increase as Chla increases, whereas the small (pico) phytoplankton community generally decreases. Within these relationships, we also found non-monotonic variations with Chla for certain pico-plankton (pico-eukaryotes, Prokaryotes and Prochlorococcus sp.) and for Green Algae and nano-sized phytoplankton. The relationships were quantified with a least-square fitting approach in order to estimate the PFTs from Chla alone. The estimated uncertainty of the relationships quantified depends on both phytoplankton types and Chla concentration. Maximum uncertainty over all groups (34.7% Chla) was found from diatom at approximately Chla = 1.07 mg m-3. However, the mean uncertainty of the relationships over all groups was 5.8 [% Chla] over the entire Chla range observed (0.02 < Chla < 6.84 mg m-3). The relationships were applied to SeaWiFS satellite Chla data from 1998 to 2009 to show the global climatological fields of the surface distribution of PFTs. Results show that microplankton are present in the mid and high latitudes, constituting ~9.0 [% Chla] of the phytoplankton community at the global surface, in which diatoms explain ~6.0 [% Chla]. Nanoplankton are ubiquious throught much of the global surface oceans except subtropical gyres, acting as a background population, constituting ~44.2 [% Chla]. Picoplankton are mostly limited in subtropical

  8. Snapshots of Proton Accommodation at a Microscopic Water Surface: Understanding the Vibrational Spectral Signatures of the Charge Defect in Cryogenically Cooled H+(H2O)n=2 – 28 Clusters

    Energy Technology Data Exchange (ETDEWEB)

    Fournier, Joseph A.; Wolke, Conrad T.; Johnson, Mark A.; Odbadrakh, Tuguldur T.; Jordan, Kenneth D.; Kathmann, Shawn M.; Xantheas, Sotiris S.

    2015-07-09

    In this Article, we review the role of gas-phase, size-selected protonated water clusters, H+(H2O)n, in the analysis of the microscopic mechanics responsible for the behavior of the excess proton in bulk water. We extend upon previous studies of the smaller, two-dimensional sheet-like structures to larger (n≥10) assemblies with three-dimensional cage morphologies which better mimic the bulk environment. Indeed, clusters in which a complete second solvation shell forms around a surface-embedded hydronium ion yield vibrational spectra where the signatures of the proton defect display strikingly similar positions and breadth to those observed in dilute acids. We investigate effects of the local structure and intermolecular interactions on the large red shifts observed in the proton vibrational signature upon cluster growth using various theoretical methods. We show that, in addition to sizeable anharmonic couplings, the position of the excess proton vibration can be traced to large increases in the electric field exerted on the embedded hydronium ion upon formation of the first and second solvation shells. MAJ acknowledges support from the U.S. Department of Energy under Grant No. DE-FG02- 06ER15800 as well as the facilities and staff of the Yale University Faculty of Arts and Sciences High Performance Computing Center, and by the National Science Foundation under Grant No. CNS 08-21132 that partially funded acquisition of the facilities. SMK and SSX acknowledge support from the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences and Biosciences. Pacific Northwest National Laboratory (PNNL) is a multiprogram national laboratory operated for DOE by Battelle. This research used resources of the National Energy Research Scientific Computing Center, which is supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.

  9. Generation of monoclonal antibodies specific for cell surface molecules expressed on early mouse endoderm.

    Science.gov (United States)

    Gadue, Paul; Gouon-Evans, Valerie; Cheng, Xin; Wandzioch, Ewa; Zaret, Kenneth S; Grompe, Markus; Streeter, Philip R; Keller, Gordon M

    2009-09-01

    The development of functional cell populations such as hepatocytes and pancreatic beta cells from embryonic stem cell (ESC) is dependent on the efficient induction of definitive endoderm early in the differentiation process. To monitor definitive endoderm formation in mouse ESC differentiation cultures in a quantitative fashion, we generated a reporter cell line that expresses human CD25 from the Foxa3 locus and human CD4 from the Foxa2 locus. Induction of these reporter ESCs with high concentrations of activin A led to the development of a CD25-Foxa3+CD4-Foxa2+ population within 4-5 days of culture. Isolation and characterization of this population showed that it consists predominantly of definitive endoderm that is able to undergo hepatic specification under the appropriate conditions. To develop reagents that can be used for studies on endoderm development from unmanipulated ESCs, from induced pluripotent stem cells, and from the mouse embryo, we generated monoclonal antibodies against the CD25-Foxa3+CD4-Foxa2+ population. With this approach, we identified two antibodies that react specifically with endoderm from ESC cultures and from the early embryo. The specificity of these antibodies enables one to quantitatively monitor endoderm development in ESC differentiation cultures, to study endoderm formation in the embryo, and to isolate pure populations of culture- or embryo-derived endodermal cells.

  10. Stage-specific, Nonlinear Surface Ozone Damage to Rice Production in China

    Science.gov (United States)

    Carter, Colin A.; Cui, Xiaomeng; Ding, Aijun; Ghanem, Dalia; Jiang, Fei; Yi, Fujin; Zhong, Funing

    2017-03-01

    China is one of the most heavily polluted nations and is also the largest agricultural producer. There are relatively few studies measuring the effects of pollution on crop yields in China, and most are based on experiments or simulation methods. We use observational data to study the impact of increased air pollution (surface ozone) on rice yields in Southeast China. We examine nonlinearities in the relationship between rice yields and ozone concentrations and find that an additional day with a maximum ozone concentration greater than 120 ppb is associated with a yield loss of 1.12% ± 0.83% relative to a day with maximum ozone concentration less than 60 ppb. We find that increases in mean ozone concentrations, SUM60, and AOT40 during panicle formation are associated with statistically significant yield losses, whereas such increases before and after panicle formation are not. We conclude that heightened surface ozone levels will potentially lead to reductions in rice yields that are large enough to have implications for the global rice market.

  11. Synthesis of silica aerogel monoliths with controlled specific surface areas and pore sizes

    Science.gov (United States)

    Gao, Bingying; Lu, Shaoxiang; Kalulu, Mulenga; Oderinde, Olayinka; Ren, Lili

    2017-07-01

    To replace traditional preparation methods of silica aerogels, a small-molecule 1,2-epoxypropane (PO) has been introduced into the preparation process instead of using ammonia as the cross-linking agent, thus generating a lightweight, high porosity, and large surface area silica aerogel monolithic. We put forward a simple solution route for the chemical synthesis of silica aerogels, which was characterized by scanning electron microscopy (SEM), TEM, XRD, FTIR, thermogravimetric analysis (TGA) and the Brunauer-Emmett-Teller (BET) method In this paper, the effect of the amount of PO on the microstructure of silica aerogels is discussed. The BET surface areas and pore sizes of the resulting silica aerogels can be freely adjusted by changing the amount of PO, which will be helpful in promoting the development of silica aerogels to fabricate other porous materials with similar requirements. We also adopted a new organic solvent sublimation drying (OSSD) method to replace traditional expensive and dangerous drying methods such as critical point drying and freeze drying. This simple approach is easy to operate and has good repeatability, which will further facilitate actual applications of silica aerogels.

  12. Aqueous bromine etching of InP: a specific surface chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Causier, A.; Bouttemy, M.; Gerard, I.; Aureau, D.; Vigneron, J.; Etcheberry, A. [Institut Lavoisier de Versailles, Versailles-Saint-Quentin University, UMR CNRS 8180, 45 Av. des Etats-Unis, 78035 Versailles (France)

    2012-06-15

    The n -InP behaviour in HBr (0.1-1.0 M)/Br{sub 2} (1.25 x 10{sup -2}M) aqueous solutions is studied by AAS, XPS and SEM-FEG. Indium AAS-titrations of the HBr/Br{sub 2} solutions demonstrate that InP undergoes an etching mechanism whatever the HBr/Br{sub 2} formulation. The etching process is always linear with time but its rate depends on the HBr concentration. XPS analyses permit to link the apparent slow-down of the dissolution process when decreasing the HBr molarity from 1.0 M to 0.1 M to the presence of a mixed (In,P){sub ox} oxide layer on the surface. Therefore, the dissolution process of InP in HBr/Br{sub 2} solution appears to be ruled by the surface chemical state (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  13. MEMS reliability in a vibration environment

    Energy Technology Data Exchange (ETDEWEB)

    TANNER,DANELLE M.; WALRAVEN,JEREMY A.; HELGESEN,KAREN SUE; IRWIN,LLOYD W.; GREGORY,DANNY LYNN; STAKE,JOHN R.; SMITH,NORMAN F.

    2000-02-03

    MicroElectricalMechanical Systems (MEMS) were subjected to a vibration environment that had a peak acceleration of 120g and spanned frequencies from 20 to 2000 Hz. The device chosen for this test was a surface-micromachined microengine because it possesses many elements (springs, gears, rubbing surfaces) that may be susceptible to vibration. The microengines were unpowered during the test. The authors observed 2 vibration-related failures and 3 electrical failures out of 22 microengines tested. Surprisingly, the electrical failures also arose in four microengines in the control group indicating that they were not vibration related. Failure analysis revealed that the electrical failures were due to shorting of stationary comb fingers to the ground plane.

  14. Windowed defocused photographic speckle vibration measurement

    CERN Document Server

    Diazdelacruz, Jose M

    2014-01-01

    The out-of-plane vibration of a rough surface causes an in-plane vibration of its speckle pattern when observed with a defocused optical photographic system. If the frequency of the oscillations is high enough, a time-averaged specklegram is recorded from which the amplitude of the vibration can be estimated. The statistical character of speckle distributions along with the pixel sampling and intensity analog-to-digital conversion inherent to electronic cameras degrade the accuracy of the amplitude measurement to an extent that is analyzed and experimentally tested in this paper. The relations limiting the mutually competing metrological features of a defocused speckle system are also deduced mathematically.

  15. Probing zeolites by vibrational spectroscopies.

    Science.gov (United States)

    Bordiga, Silvia; Lamberti, Carlo; Bonino, Francesca; Travert, Arnaud; Thibault-Starzyk, Frédéric

    2015-10-21

    This review addresses the most relevant aspects of vibrational spectroscopies (IR, Raman and INS) applied to zeolites and zeotype materials. Surface Brønsted and Lewis acidity and surface basicity are treated in detail. The role of probe molecules and the relevance of tuning both the proton affinity and the steric hindrance of the probe to fully understand and map the complex site population present inside microporous materials are critically discussed. A detailed description of the methods needed to precisely determine the IR absorption coefficients is given, making IR a quantitative technique. The thermodynamic parameters of the adsorption process that can be extracted from a variable-temperature IR study are described. Finally, cutting-edge space- and time-resolved experiments are reviewed. All aspects are discussed by reporting relevant examples. When available, the theoretical literature related to the reviewed experimental results is reported to support the interpretation of the vibrational spectra on an atomic level.

  16. Area-Specific Cell Stimulation via Surface-Mediated Gene Transfer Using Apatite-Based Composite Layers

    Directory of Open Access Journals (Sweden)

    Yushin Yazaki

    2015-04-01

    Full Text Available Surface-mediated gene transfer systems using biocompatible calcium phosphate (CaP-based composite layers have attracted attention as a tool for controlling cell behaviors. In the present study we aimed to demonstrate the potential of CaP-based composite layers to mediate area-specific dual gene transfer and to stimulate cells on an area-by-area basis in the same well. For this purpose we prepared two pairs of DNA–fibronectin–apatite composite (DF-Ap layers using a pair of reporter genes and pair of differentiation factor genes. The results of the area-specific dual gene transfer successfully demonstrated that the cells cultured on a pair of DF-Ap layers that were adjacently placed in the same well showed specific gene expression patterns depending on the gene that was immobilized in theunderlying layer. Moreover, preliminary real-time PCR results indicated that multipotential C3H10T1/2 cells may have a potential to change into different types of cells depending on the differentiation factor gene that was immobilized in the underlying layer, even in the same well. Because DF-Ap layers have a potential to mediate area-specific cell stimulation on their surfaces, they could be useful in tissue engineering applications.

  17. Synoptic relationships between surface Chlorophyll-a and diagnostic pigments specific to phytoplankton functional types

    Directory of Open Access Journals (Sweden)

    M. Noguchi-Aita

    2011-02-01

    Full Text Available Error-quantified, synoptic-scale relationships between chlorophyll-a (Chl-a and phytoplankton pigment groups at the sea surface are presented. A total of ten pigment groups were considered to represent three Phytoplankton Size Classes (PSCs, micro-, nano- and picoplankton and seven Phytoplankton Functional Types (PFTs, i.e. diatoms, dinoflagellates, green algae, prymnesiophytes (haptophytes, pico-eukaryotes, prokaryotes and Prochlorococcus sp.. The observed relationships between Chl-a and PSCs/PFTs were well-defined at the global scale to show that a community shift of phytoplankton at the basin and global scales is reflected by a change in Chl-a of the total community. Thus, Chl-a of the total community can be used as an index of not only phytoplankton biomass but also of their community structure. Within these relationships, we also found non-monotonic variations with Chl-a for certain pico-sized phytoplankton (pico-eukaryotes, Prokaryotes and Prochlorococcus sp. and nano-sized phytoplankton (Green algae, prymnesiophytes. The relationships were quantified with a least-square fitting approach in order to enable an estimation of the PFTs from Chl-a where PFTs are expressed as a percentage of the total Chl-a. The estimated uncertainty of the relationships depends on both PFT and Chl-a concentration. Maximum uncertainty of 31.8% was found for diatoms at Chl-a = 0.49 mg m−3. However, the mean uncertainty of the relationships over all PFTs was 5.9% over the entire Chl-a range observed in situ (0.02 < Chl-a < 4.26 mg m−3. The relationships were applied to SeaWiFS satellite Chl-a data from 1998 to 2009 to show the global climatological fields of the surface distribution of PFTs. Results show that microplankton are present in the mid and high latitudes, constituting only ~10.9% of the entire phytoplankton community in the mean field for 1998–2009, in which diatoms explain ~7.5%. Nanoplankton are ubiquitous throughout the global surface oceans

  18. Surface magnetic contribution in zinc ferrite thin films studied by element- and site-specific XMCD hysteresis-loops

    Energy Technology Data Exchange (ETDEWEB)

    Mendoza Zélis, P.; Pasquevich, G.A. [IFLP-CCT-La Plata-CONICET and Departamento de Física, Facultad de Ciencias Exactas, C. C. 67, Universidad Nacional de La Plata, 1900 La Plata (Argentina); Departamento de Ciencias Básicas, Facultad de Ingeniería, Universidad Nacional de La Plata, 1900 La Plata (Argentina); Salcedo Rodríguez, K.L.; Sánchez, F.H. [IFLP-CCT-La Plata-CONICET and Departamento de Física, Facultad de Ciencias Exactas, C. C. 67, Universidad Nacional de La Plata, 1900 La Plata (Argentina); Rodríguez Torres, C.E., E-mail: torres@fisica.unlp.edu.ar [IFLP-CCT-La Plata-CONICET and Departamento de Física, Facultad de Ciencias Exactas, C. C. 67, Universidad Nacional de La Plata, 1900 La Plata (Argentina)

    2016-12-01

    Element- and site-specific magnetic hysteresis-loops measurements on a zinc ferrite (ZnFe{sub 2}O{sub 4}) thin film were performed by X-ray magnetic circular dichroism. Results show that iron in octahedral and tetrahedral sites of spinel structure are coupled antiferromagnetically between them, and when magnetic field is applied the magnetic moment of the ion located at octahedral sites aligns along the field direction. The magnetic measurements reveal a distinctive response of the surface with in-plane anisotropy and an effective anisotropy constant value of 12.6 kJ/m{sup 3}. This effective anisotropy is due to the combining effects of demagnetizing field and, volume and surface magnetic anisotropies K{sub V} =3.1 kJ/m{sup 3} and K{sub S} =16 μJ/m{sup 2}. - Highlights: • Surface magnetic response in ZnFe{sub 2}O{sub 4} film (thickness t ∼57 nm) by XMCD is studied. • Measurements of magnetic moment vs. applied field cycles via XMCD are presented. • Fe{sup 3+} at A- and B-sites are coupled antiferromagnetically between them. • A distinctive response of the surface with in-plane magnetic anisotropy is determined. • Volume and surface magnetic anisotropy are determined: 3.1 kJ/m{sup 3} and 16 μJ/m{sup 2}.

  19. Polymer bilayer formation due to specific interactions between beta-cyclodextrin and adamantane: a surface force study.

    Science.gov (United States)

    Blomberg, Eva; Kumpulainen, Atte; David, Christelle; Amiel, Catherine

    2004-11-23

    The purposes of this study are to utilize the interactions between an adamantane end-capped poly(ethylene oxide) (PEO) and a cationic polymer of beta-cyclodextrin to build polymer bilayers on negatively charged surfaces, and to investigate the interactions between such layers. The association of this system in solution has been studied by rheology, light scattering, and fluorescence measurements. It was found that the adamantane-terminated PEO (PEO-Ad) mixed with the beta-cyclodextrin polymer gives complexes where the interpolymer links are formed by specific inclusion of the adamantane groups in the beta-cyclodextrin cavities. This results in a higher viscosity of the solution and growth of intermolecular clusters. The interactions between surfaces coated with a cationized beta-cyclodextrin polymer across a water solution containing PEO-Ad polymers were studied by employing the interferometric surface force apparatus (SFA). In the first step, the interaction between mica surfaces coated with the cationized beta-cyclodextrin polymer in pure water was investigated. It was found that the beta-cyclodextrin polymer adsorbs onto mica and almost neutralizes the surface charge. The adsorbed layers of the beta-cyclodextrin polymer are rather compact, with a layer thickness of about 60 A (30 A per surface). Upon separation, a very weak attractive force is observed. The beta-cyclodextrin solution was then diluted by pure water by a factor of 3000 and a PEO-Ad polymer was introduced into the solution. Two different architectures of the PEO-Ad polymer were investigated: a four-arm structure and a linear structure. After the adsorption of the PEO polymer onto the beta-cyclodextrin layer reached equilibrium, the forces were measured again. It was found that the weak repulsive long-range force had disappeared and an attractive force caused the surfaces to jump into contact, and that the compressed layer thickness had increased. The attractive force is interpreted as being due to

  20. Variant surface antigen-specific IgG and protection against clinical consequences of pregnancy-associated Plasmodium falciparum malaria

    DEFF Research Database (Denmark)

    Staalsoe, Trine; Shulman, Caroline E; Bulmer, Judith N

    2004-01-01

    BACKGROUND: Pregnancy-associated malaria caused by Plasmodium falciparum adherence to chondroitin sulfate A in the placental intervillous space is a major cause of low birthweight and maternal anaemia in areas of endemic P falciparum transmission. Adhesion-blocking antibodies that specifically...... recognise parasite-encoded variant surface antigens (VSA) are associated with resistance to pregnancy-associated malaria. We looked for a possible relation between VSA-specific antibody concentrations, placental infection, and protection from low birthweight and maternal anaemia. METHODS: We used flow...... cytometry to measure VSA-specific IgG concentrations in plasma samples taken during child birth from 477 Kenyan women selected from a cohort of 910 women on the basis of HIV-1 status, gravidity, and placental histology. We measured VSA expressed by one placental P falciparum isolate and two isolates...

  1. Recent advances in micro-vibration isolation

    Science.gov (United States)

    Liu, Chunchuan; Jing, Xingjian; Daley, Steve; Li, Fengming

    2015-05-01

    Micro-vibration caused by disturbance sources onboard spacecraft can severely degrade the working environment of sensitive payloads. Some notable vibration control methods have been developed particularly for the suppression or isolation of micro-vibration over recent decades. Usually, passive isolation techniques are deployed in aerospace engineering. Active isolators, however, are often proposed to deal with the low frequency vibration that is common in spacecraft. Active/passive hybrid isolation has also been effectively used in some spacecraft structures for a number of years. In semi-active isolation systems, the inherent structural performance can be adjusted to deal with variation in the aerospace environment. This latter approach is potentially one of the most practical isolation techniques for micro-vibration isolation tasks. Some emerging advanced vibration isolation methods that exploit the benefits of nonlinearity have also been reported in the literature. This represents an interesting and highly promising approach for solving some challenging problems in the area. This paper serves as a state-of-the-art review of the vibration isolation theory and/or methods which were developed, mainly over the last decade, specifically for or potentially could be used for, micro-vibration control.

  2. The Brain-Specific Beta4 Subunit Downregulates BK Channel Cell Surface Expression

    OpenAIRE

    Sonal Shruti; Joanna Urban-Ciecko; Fitzpatrick, James A.; Robert Brenner; Bruchez, Marcel P.; Alison L Barth

    2012-01-01

    The large-conductance K(+) channel (BK channel) can control neural excitability, and enhanced channel currents facilitate high firing rates in cortical neurons. The brain-specific auxiliary subunit β4 alters channel Ca(++)- and voltage-sensitivity, and β4 knock-out animals exhibit spontaneous seizures. Here we investigate β4's effect on BK channel trafficking to the plasma membrane. Using a novel genetic tag to track the cellular location of the pore-forming BKα subunit in living cells, we fi...

  3. The Soil Characteristic Curve at Low Water Contents: Relations to Specific Surface Area and Texture

    DEFF Research Database (Denmark)

    Resurreccion, Augustus; Møldrup, Per; Schjønning, Per;

    Accurate description of the soil-water retention curve (SWRC) at low water contents is important for simulating water dynamics, plant-water relations, and microbial processes in surface soil. Soil-water retention at soil-water matric potential of less than -10 MPa, where adsorptive forces dominate...... that measurements by traditional pressure plate apparatus generally overestimated water contents at -1.5 MPa (plant wilting point). The 41 soils were classified into four textural classes based on the so-called Dexter index n (= CL/OC), and the Tuller-Or (TO) general scaling model describing the water film...... thickness at a given soil-water matric potential (low organic soils with n > 10, the estimated SA from the dry soil-water retention was in good agreement with the SA measured using ethylene glycol monoethyl ether (SA_EGME). A strong relationship between the ratio...

  4. The surface properties of SOA generated from limonene and toluene using specific molecular probes: exploration of a new experimental technique

    Directory of Open Access Journals (Sweden)

    B. Demirdjian

    2005-02-01

    Full Text Available A new experimental technique of characterizing the aerosol-atmosphere surface has been explored using three examples: the secondary organic aerosols (SOA resulting from the reaction of limonene with O3 and from the photooxidation of toluene in comparison with the combustion aerosol (soot from a toluene diffusion flame. Rather than investigating the bulk composition of the aerosol by complete chemical analysis and identification of the many dozens if not more of constituent compounds we have interrogated the type and number of functional groups located at the aerosol surface by interacting them with specific molecular probes such as O3, NO2, N(CH33, and NH2OH to probe for the presence of oxidizable sites, acidic sites and carbonyl functionalities, respectively, that are present on the surface of the aerosol particle. In practice, typical amounts of one to a few mg of laboratory-generated SOA of limonene, toluene and soot have been deposited on a PTFE membrane filter that subsequently has been transferred to a molecular flow reactor used for the titration reaction of the surface functional groups by the molecular probes. Absolute amounts Ni with i=O3, NO2, N(CH33, NH2OH of probe molecules taken up by the filter sample measured using molecular beam sampling mass spectrometry have been converted into the number of surface group functionalities per unit surface area S using the aerosol particle distribution function (PDF of limonene and toluene SOA and the BET total surface area of toluene flame soot to result in Ni/S. Arguments are presented that support the transfer of the PDF of the suspended to the aerosol collected on the Teflon filter.

  5. Application specific beam profiles: new surface and thin-film refinement processes using beam shaping technologies

    Science.gov (United States)

    Hauschild, Dirk

    2017-02-01

    Today, the use of laser photons for materials processing is a key technology in nearly all industries. Most of the applications use circular beam shapes with Gaussian intensity distribution that is given by the resonator of the laser or by the power delivery via optical fibre. These beam shapes can be typically used for material removal with cutting or drilling and for selective removal of material layers with ablation processes. In addition to the removal of materials, it is possible to modify and improve the material properties in case the dose of laser photons and the resulting light-material interaction addresses a defined window of energy and dwell-time. These process windows have typically dwell-times between µs and s because of using sintering, melting, thermal diffusion or photon induced chemical and physical reaction mechanisms. Using beam shaping technologies the laser beam profiles can be adapted to the material properties and time-temperature and the space-temperature envelopes can be modified to enable selective annealing or crystallization of layers or surfaces. Especially the control of the process energy inside the beam and at its edges opens a large area of laser applications that can be addressed only with an optimized spatial and angular beam profile with down to sub-percent intensity variation used in e.g. immersion lithography tools with ArF laser sources. LIMO will present examples for new beam shapes and related material refinement processes even on large surfaces and give an overview about new mechanisms in laser material processing for current and coming industrial applications.

  6. Active Control for Multinode Unbalanced Vibration of Flexible Spindle Rotor System with Active Magnetic Bearing

    OpenAIRE

    Xiaoli Qiao; Guojun Hu

    2017-01-01

    The unbalanced vibration of the spindle rotor system in high-speed cutting processes not only seriously affects the surface quality of the machined products, but also greatly reduces the service life of the electric spindle. However, since the unbalanced vibration is often distributed on different node positions, the multinode unbalanced vibration greatly exacerbates the difficulty of vibration control. Based on the traditional influence coefficient method for controlling the vibration of a f...

  7. Vibration of hydraulic machinery

    CERN Document Server

    Wu, Yulin; Liu, Shuhong; Dou, Hua-Shu; Qian, Zhongdong

    2013-01-01

    Vibration of Hydraulic Machinery deals with the vibration problem which has significant influence on the safety and reliable operation of hydraulic machinery. It provides new achievements and the latest developments in these areas, even in the basic areas of this subject. The present book covers the fundamentals of mechanical vibration and rotordynamics as well as their main numerical models and analysis methods for the vibration prediction. The mechanical and hydraulic excitations to the vibration are analyzed, and the pressure fluctuations induced by the unsteady turbulent flow is predicted in order to obtain the unsteady loads. This book also discusses the loads, constraint conditions and the elastic and damping characters of the mechanical system, the structure dynamic analysis, the rotor dynamic analysis and the system instability of hydraulic machines, including the illustration of monitoring system for the instability and the vibration in hydraulic units. All the problems are necessary for vibration pr...

  8. Real-Time Analysis of Specific Protein-DNA Interactions with Surface Plasmon Resonance

    Directory of Open Access Journals (Sweden)

    Markus Ritzefeld

    2012-01-01

    Full Text Available Several proteins, like transcription factors, bind to certain DNA sequences, thereby regulating biochemical pathways that determine the fate of the corresponding cell. Due to these key positions, it is indispensable to analyze protein-DNA interactions and to identify their mode of action. Surface plasmon resonance is a label-free method that facilitates the elucidation of real-time kinetics of biomolecular interactions. In this article, we focus on this biosensor-based method and provide a detailed guide how SPR can be utilized to study binding of proteins to oligonucleotides. After a description of the physical phenomenon and the instrumental realization including fiber-optic-based SPR and SPR imaging, we will continue with a survey of immobilization methods. Subsequently, we will focus on the optimization of the experiment, expose pitfalls, and introduce how data should be analyzed and published. Finally, we summarize several interesting publications of the last decades dealing with protein-DNA and RNA interaction analysis by SPR.

  9. Identifying and tracing potential energy surfaces of electronic excitations with specific character via their transition origins: application to oxirane.

    Science.gov (United States)

    Li, Jian-Hao; Zuehlsdorff, T J; Payne, M C; Hine, N D M

    2015-05-14

    We show that the transition origins of electronic excitations identified by quantified natural transition orbital (QNTO) analysis can be employed to connect potential energy surfaces (PESs) according to their character across a wide range of molecular geometries. This is achieved by locating the switching of transition origins of adiabatic potential surfaces as the geometry changes. The transition vectors for analysing transition origins are provided by linear response time-dependent density functional theory (TDDFT) calculations under the Tamm-Dancoff approximation. We study the photochemical CO ring opening of oxirane as an example and show that the results corroborate the traditional Gomer-Noyes mechanism derived experimentally. The knowledge of specific states for the reaction also agrees well with that given by previous theoretical work using TDDFT surface-hopping dynamics that was validated by high-quality quantum Monte Carlo calculations. We also show that QNTO can be useful for considerably larger and more complex systems: by projecting the excitations to those of a reference oxirane molecule, the approach is able to identify and analyse specific excitations of a trans-2,3-diphenyloxirane molecule.

  10. Sulfur-doped nanoporous carbon spheres with ultrahigh specific surface area and high electrochemical activity for supercapacitor

    Science.gov (United States)

    Liu, Simin; Cai, Yijin; Zhao, Xiao; Liang, Yeru; Zheng, Mingtao; Hu, Hang; Dong, Hanwu; Jiang, Sanping; Liu, Yingliang; Xiao, Yong

    2017-08-01

    Development of facile and scalable synthesis process for the fabrication of nanoporous carbon materials with large specific surface areas, well-defined nanostructure, and high electrochemical activity is critical for the high performance energy storage applications. The key issue is the dedicated balance between the ultrahigh surface area and highly porous but interconnected nanostructure. Here, we demonstrate the fabrication of new sulfur doped nanoporous carbon sphere (S-NCS) with the ultrahigh surface area up to 3357 m2 g-1 via a high-temperature hydrothermal carbonization and subsequent KOH activation process. The as-prepared S-NCS which integrates the advantages of ultrahigh porous structure, well-defined nanospherical and modification of heteroatom displays excellent electrochemical performance. The best performance is obtained on S-NCS prepared by the hydrothermal carbonization of sublimed sulfur and glucose, S-NCS-4, reaching a high specific capacitance (405 F g-1 at a current density of 0.5 A g-1) and outstanding cycle stability. Moreover, the symmetric supercapacitor is assembled by S-NCS-4 displays a superior energy density of 53.5 Wh kg-1 at the power density of 74.2 W kg-1 in 1.0 M LiPF6 EC/DEC. The synthesis method is simple and scalable, providing a new route to prepare highly porous and heteroatom-doped nanoporous carbon spheres for high performance energy storage applications.

  11. Biotemplated synthesis of high specific surface area copper-doped hollow spherical titania and its photocatalytic research for degradating chlorotetracycline

    Science.gov (United States)

    Bu, Dan; Zhuang, Huisheng

    2013-01-01

    Copper-doped titania (Cu/TiO2) hollow microspheres were fabricated using the rape pollen as biotemplates via an improved sol-gel method and a followed calcinations process. In the fabricated process, a titanium(IV)-isopropoxide-based sol directly coated onto the surface of rape pollen. Subsequently, after calcinations, rape pollen was removed by high temperature and the hollow microsphere structure was retained. The average diameter of as-obtained hollow microspheres is 15-20 μm and the thickness of shell is approximately 0.6 μm. Knowing from XRD results, the main crystal phase of microspheres is anatase, coupled with rutile. The specific surface area varied between 141.80 m2/g and 172.51 m2/g. This hollow sphere photocatalysts with high specific surface area exhibited stronger absorption ability and higher photoactivity, stimulated by visible light. The degradation process of chlortetracycline (CTC) solution had been studied. The degradated results indicate that CTC could be effective degradated by fabricated hollow spherical materials. And the intermediate products formed in the photocatalytic process had been identified.

  12. Statistical quality control through overall vibration analysis

    Science.gov (United States)

    Carnero, M. a. Carmen; González-Palma, Rafael; Almorza, David; Mayorga, Pedro; López-Escobar, Carlos

    2010-05-01

    The present study introduces the concept of statistical quality control in automotive wheel bearings manufacturing processes. Defects on products under analysis can have a direct influence on passengers' safety and comfort. At present, the use of vibration analysis on machine tools for quality control purposes is not very extensive in manufacturing facilities. Noise and vibration are common quality problems in bearings. These failure modes likely occur under certain operating conditions and do not require high vibration amplitudes but relate to certain vibration frequencies. The vibration frequencies are affected by the type of surface problems (chattering) of ball races that are generated through grinding processes. The purpose of this paper is to identify grinding process variables that affect the quality of bearings by using statistical principles in the field of machine tools. In addition, an evaluation of the quality results of the finished parts under different combinations of process variables is assessed. This paper intends to establish the foundations to predict the quality of the products through the analysis of self-induced vibrations during the contact between the grinding wheel and the parts. To achieve this goal, the overall self-induced vibration readings under different combinations of process variables are analysed using statistical tools. The analysis of data and design of experiments follows a classical approach, considering all potential interactions between variables. The analysis of data is conducted through analysis of variance (ANOVA) for data sets that meet normality and homoscedasticity criteria. This paper utilizes different statistical tools to support the conclusions such as chi squared, Shapiro-Wilks, symmetry, Kurtosis, Cochran, Hartlett, and Hartley and Krushal-Wallis. The analysis presented is the starting point to extend the use of predictive techniques (vibration analysis) for quality control. This paper demonstrates the existence

  13. Mechanical vibration of viscoelastic liquid droplets

    Science.gov (United States)

    Sharp, James; Harrold, Victoria

    2014-03-01

    The resonant vibrations of viscoelastic sessile droplets supported on different substrates were monitored using a simple laser light scattering technique. In these experiments, laser light was reflected from the surfaces of droplets of high Mw poly acrylamide-co-acrylic acid (PAA) dissolved in water. The scattered light was allowed to fall on the surface of a photodiode detector and a mechanical impulse was applied to the drops using a vibration motor mounted beneath the substrates. The mechanical impulse caused the droplets to vibrate and the scattered light moved across the surface of the photodiode. The resulting time dependent photodiode signal was then Fourier transformed to obtain the mechanical vibrational spectra of the droplets. The frequencies and widths of the resonant peaks were extracted for droplets containing different concentrations of PAA and with a range of sizes. This was repeated for PAA loaded water drops on surfaces which displayed different values of the three phase contact angle. The results were compared to a simple model of droplet vibration which considers the formation of standing wave states on the surface of a viscoelastic droplet. We gratefully acknowledge the support of the Leverhulme trust under grant number RPG-2012-702.

  14. A 38-kilobase pathogenicity island specific for Mycobacterium avium subsp. paratuberculosis encodes cell surface proteins expressed in the host.

    Science.gov (United States)

    Stratmann, Janin; Strommenger, Birgit; Goethe, Ralph; Dohmann, Karen; Gerlach, Gerald-F; Stevenson, Karen; Li, Ling-Ling; Zhang, Qing; Kapur, Vivek; Bull, Tim J

    2004-03-01

    We have used representational difference analysis to identify a novel Mycobacterium avium subsp. paratuberculosis-specific ABC transporter operon (mpt), which comprises six open reading frames designated mptA to -F and is immediately preceded by two putative Fur boxes. Functional genomics revealed that the mpt operon is flanked on one end by a fep cluster encoding proteins involved in the uptake of Fe(3+) and on the other end by a sid cluster encoding non-ribosome-dependent heterocyclic siderophore synthases. Together these genes form a 38-kb M. avium subsp. paratuberculosis-specific locus flanked by an insertion sequence similar to IS1110. Expression studies using Western blot analyses showed that MptC is present in the envelope fraction of M. avium subsp. paratuberculosis. The MptD protein was shown to be surface exposed, using a specific phage (fMptD) isolated from a phage-peptide library, by differential screening of Mycobacterium smegmatis transformants. The phage fMptD-derived peptide could be used in a peptide-mediated capture PCR with milk from infected dairy herds, thereby showing surface-exposed expression of the MptD protein in the host. Together, these data suggest that the 38-kb locus constitutes an M. avium subsp. paratuberculosis pathogenicity island.

  15. COMPLEX HEAT TRANSFER ENHANCEMENT BY FLUID INDUCED VIBRATION

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    A new method of heat transfer enhancement by fluid induced vibration was put forward, and its theoretical analysis and experimental study were performed. Though people always try to prophylaxis fluid induced vibration for regarding it as an accident, the utilization space of fluid induced vibration is still very large. The in-surface and out-surface vibrations which come from the fluid induce elastic tube bundles, can effectively increase the convective heat transfer coefficient, and also decrease the fouling resistance, then increase the heat transfer coefficient remarkably.

  16. An algorithm for the use of the Lagrangian specification in Newtonian fluid mechanics and applications to free-surface flow

    DEFF Research Database (Denmark)

    Bach, P; Hassager, Ole

    1985-01-01

    An algorithm is constructed for the use of the Lagrangian kinematc specification in Newtonian fluid mechanics. The algorithm is implemented with a finite-element method, and it is demonstrated that the method accurately describes free-surface flow, including the effects of surface tension, with t......-plate geometry show that the measured apparent contact angle is not the true angle, and that the true angle is always very close to the equilibrium value......., with the use of just bilinear isoparametric elements. Moving contact lines are modelled with a small amount of slip near the contact lines. The contact angle boundary condition is included in the form of a net interfacial force specified at the contact line. Simulations of measurements in a parallel...

  17. A group of Giardia lamblia variant-specific surface protein (VSP) genes with nearly identical 5' regions.

    Science.gov (United States)

    Yang, Y; Adam, R D

    1995-12-01

    The surfaces of Giardia lamblia trophozoites contain one of a set of variant-specific surface proteins. The genes encoding these proteins are highly conserved at the 3' terminus, but frequently demonstrate little similarity in the remainder of the coding region. This report describes a family of vsp genes highly similar to a repeat-containing vsp gene (vspC5) at the 5' coding and flanking regions, but which diverge abruptly from vspC5 in the first repeat and do not themselves contain full copies of the repeat. This observation suggests the possibility that recombination among different vsp genes may have played a role in development of the vsp gene repertoire.

  18. Surface magnetic contribution in zinc ferrite thin films studied by element- and site-specific XMCD hysteresis-loops

    Science.gov (United States)

    Mendoza Zélis, P.; Pasquevich, G. A.; Salcedo Rodríguez, K. L.; Sánchez, F. H.; Rodríguez Torres, C. E.

    2016-12-01

    Element- and site-specific magnetic hysteresis-loops measurements on a zinc ferrite (ZnFe2O4) thin film were performed by X-ray magnetic circular dichroism. Results show that iron in octahedral and tetrahedral sites of spinel structure are coupled antiferromagnetically between them, and when magnetic field is applied the magnetic moment of the ion located at octahedral sites aligns along the field direction. The magnetic measurements reveal a distinctive response of the surface with in-plane anisotropy and an effective anisotropy constant value of 12.6 kJ/m3. This effective anisotropy is due to the combining effects of demagnetizing field and, volume and surface magnetic anisotropies KV =3.1 kJ/m3 and KS =16 μJ/m2.

  19. Experimental investigation of active machine tool vibration control

    Science.gov (United States)

    Rojas, J.; Liang, Chen; Geng, Zheng J.

    1996-05-01

    The successful vibration reduction of machine tools during machining process can improve productivity, increase quality, and reduce tool wear. This paper will present our initial investigation in the application of smart material technologies in machine tool vibration control using magnetostrictive actuators and electrorheological elastomer dampers on an industrial Sheldon horizontal lathe. The dynamics of the machining process are first studied, which reveals the complexity in the machine tool vibration response and the challenge to the active control techniques. The active control experiment shows encouraging results. The use of electrorheological elastomer damping device for active/passive vibration control provides significant vibration reduction in the high frequency range and great improvement in the workpiece surface finishing. The research presented in this paper demonstrates that the combination of active and active/passive vibration control techniques is very promising for successful machine tool vibration control.

  20. Thermal Vibrational Convection

    Science.gov (United States)

    Gershuni, G. Z.; Lyubimov, D. V.

    1998-08-01

    Recent increasing awareness of the ways in which vibrational effects can affect low-gravity experiments have renewed interest in the study of thermal vibrational convection across a wide range of fields. For example, in applications where vibrational effects are used to provide active control of heat and mass transfer, such as in heat exchangers, stirrers, mineral separators and crystal growth, a sound understanding of the fundamental theory is required. In Thermal Vibrational Convection, the authors present the theory of vibrational effects caused by a static gravity field, and of fluid flows which appear under vibration in fluid-filled cavities. The first part of the book discusses fluid-filled cavities where the fluid motion only appears in the presence of temperature non-uniformities, while the second considers those situations where the vibrational effects are caused by a non-uniform field. Throughout, the authors concentrate on consideration of high frequency vibrations, where averaging methods can be successfully applied in the study of the phenomena. Written by two of the pioneers in this field, Thermal Vibrational Convection will be of great interest to scientists and engineers working in the many areas that are concerned with vibration, and its effect on heat and mass transfer. These include hydrodynamics, hydro-mechanics, low gravity physics and mechanics, and geophysics. The rigorous approach adopted in presenting the theory of this fascinating and highly topical area will facilitate a greater understanding of the phenomena involved, and will lead to the development of more and better-designed experiments.