Science.gov

Sample records for high-volume electrostatic field

  1. Electrostatic Field Invisibility Cloak

    PubMed Central

    Lan, Chuwen; Yang, Yuping; Geng, Zhaoxin; Li, Bo; Zhou, Ji

    2015-01-01

    The invisibility cloak has been drawing much attention due to its new concept for manipulating many physical fields, from oscillating wave fields (electromagnetic, acoustic and elastic) to static magnetic fields, dc electric fields, and diffusive fields. Here, an electrostatic field invisibility cloak has been theoretically investigated and experimentally demonstrated to perfectly hide two dimensional objects without disturbing their external electrostatic fields. The desired cloaking effect has been achieved via both cancelling technology and transformation optics (TO). This study demonstrates a novel way for manipulating electrostatic fields, which shows promise for a wide range of potential applications. PMID:26552343

  2. Electrostatic Field Invisibility Cloak.

    PubMed

    Lan, Chuwen; Yang, Yuping; Geng, Zhaoxin; Li, Bo; Zhou, Ji

    2015-11-10

    The invisibility cloak has been drawing much attention due to its new concept for manipulating many physical fields, from oscillating wave fields (electromagnetic, acoustic and elastic) to static magnetic fields, dc electric fields, and diffusive fields. Here, an electrostatic field invisibility cloak has been theoretically investigated and experimentally demonstrated to perfectly hide two dimensional objects without disturbing their external electrostatic fields. The desired cloaking effect has been achieved via both cancelling technology and transformation optics (TO). This study demonstrates a novel way for manipulating electrostatic fields, which shows promise for a wide range of potential applications.

  3. FIELD EVALUATION OF A HIGH-VOLUME DICHOTOMOUS SAMPLER

    EPA Science Inventory

    This study presents the field evaluation of a high-volume dichotomous sampler that collects coarse (PM10-2.5) and fine (PM2.5) particulate matter. The key feature of this device is the utilization of a round-nozzle virtual impactor with a 50% cutpoint at 2.5 5m to split PM10 into...

  4. FIELD EVALUATION OF A HIGH-VOLUME DICHOTOMOUS SAMPLER

    EPA Science Inventory

    This study presents the field evaluation of a high-volume dichotomous sampler that collects coarse (PM10-2.5) and fine (PM2.5) particulate matter. The key feature of this device is the utilization of a round-nozzle virtual impactor with a 50% cutpoint at 2.5 5m to split PM10 into...

  5. High Volume Manufacturing and Field Stability of MEMS Products

    NASA Astrophysics Data System (ADS)

    Martin, Jack

    Low volume MEMS/NEMS production is practical when an attractive concept is implemented with business, manufacturing, packaging, and test support. Moving beyond this to high volume production adds requirements on design, process control, quality, product stability, market size, market maturity, capital investment, and business systems. In a broad sense, this chapter uses a case study approach: It describes and compares the silicon-based MEMS accelerometers, pressure sensors, image projection systems, and gyroscopes that are in high volume production. Although they serve several markets, these businesses have common characteristics. For example, the manufacturing lines use automated semiconductor equipment and standard material sets to make consistent products in large quantities. Standard, well controlled processes are sometimes modified for a MEMS product. However, novel processes that cannot run with standard equipment and material sets are avoided when possible. This reliance on semiconductor tools, as well as the organizational practices required to manufacture clean, particle-free products partially explains why the MEMS market leaders are integrated circuit manufacturers. There are other factors. MEMS and NEMS are enabling technologies, so it can take several years for high volume applications to develop. Indeed, market size is usually a strong function of price. This becomes a vicious circle, because low price requires low cost - a result that is normally achieved only after a product is in high volume production. During the early years, IC companies reduced cost and financial risk by using existing facilities for low volume MEMS production. As a result, product architectures are partially determined by capabilities developed for previous products. This chapter includes a discussion of MEMS product architecture with particular attention to the impact of electronic integration, packaging, and surfaces. Packaging and testing are critical, because they are

  6. High Volume Manufacturing and Field Stability of MEMS Products

    NASA Astrophysics Data System (ADS)

    Martin, Jack

    Low volume MEMS/NEMS production is practical when an attractive concept is implemented with business, manufacturing, packaging, and test support. Moving beyond this to high volume production adds requirements on design, process control, quality, product stability, market size, market maturity, capital investment, and business systems. In a broad sense, this chapter uses a case study approach: It describes and compares the silicon-based MEMS accelerometers, pressure sensors, image projection systems, and gyroscopes that are in high volume production. Although they serve several markets, these businesses have common characteristics. For example, the manufacturing lines use automated semiconductor equipment and standard material sets to make consistent products in large quantities. Standard, well controlled processes are sometimes modified for a MEMS product. However, novel processes that cannot run with standard equipment and material sets are avoided when possible. This reliance on semiconductor tools, as well as the organizational practices required to manufacture clean, particle-free products partially explains why the MEMS market leaders are integrated circuit manufacturers. There are other factors. MEMS and NEMS are enabling technologies, so it can take several years for high volume applications to develop. Indeed, market size is usually a strong function of price. This becomes a vicious circle, because low price requires low cost - a result that is normally achieved only after a product is in high volume production. During the early years, IC companies reduced cost and financial risk by using existing facilities for low volume MEMS production. As a result, product architectures are partially determined by capabilities developed for previous products. This chapter includes a discussion of MEMS product architecture with particular attention to the impact of electronic integration, packaging, and surfaces. Packaging and testing are critical, because they are

  7. Electrostatic air filters generated by electric fields

    SciTech Connect

    Bergman, W.; Biermann, A.H.; Hebard, H.D.; Lum, B.Y.; Kuhl, W.D.

    1981-01-27

    This paper presents theoretical and experimental findings on fibrous filters converted to electrostatic operation by a nonionizing electric field. Compared to a conventional fibrous filter, the electrostatic filter has a higher efficiency and a longer, useful life. The increased efficiency is attributed to a time independent attraction between polarized fibers and charged, polarized particles and a time dependent attraction between charged fibers and charged, polarized particles. The charge on the fibers results from a dynamic process of charge accumulation due to the particle deposits and a charge dissipation due to the fiber conductivity.

  8. Controlling Charged Particles with Inhomogeneous Electrostatic Fields

    NASA Technical Reports Server (NTRS)

    Herrero, Federico A. (Inventor)

    2016-01-01

    An energy analyzer for a charged-particle spectrometer may include a top deflection plate and a bottom deflection plate. The top and bottom deflection plates may be non-symmetric and configured to generate an inhomogeneous electrostatic field when a voltage is applied to one of the top or bottom deflection plates. In some instances, the top and bottom deflection plates may be L-shaped deflection plates.

  9. Electrostatic fields in a dusty Martian environment

    NASA Technical Reports Server (NTRS)

    Sentman, D. D.

    1991-01-01

    While there have been several studies suggesting the possibility of electrical activity on Mars, to date there have been no measurements to search for evidence of such activity. In the absence of widespread water clouds and convective storm systems similar to those on the Earth and Jupiter, the most likely candidate for the creation of electrostatic charges and fields is triboelectric charging of dust, i.e., the friction between blown dust and the ground, and of dust particles with each other. Terrestrial experience demonstrates that electric fields 5 to 15 kV-m(exp -1) are not uncommon in dust storms and dust devils in desert regions, where the polarity varies according to the chemical composition and grain size. Simple laboratory experiments have demonstrated that modest electrostatic fields of roughly 5,000 V-m(exp -1) may be produced, along with electrical spark discharges and glow discharges, in a simulation of a dusty, turbulent Martian surface environment. While the Viking landers operated for several years with no apparent deleterious effects from electrostatic charging, this may have been at least partly due to good engineering design utilizing pre-1976 electronic circuitry to minimize the possibility of differential charging among the various system components. However, free roaming rovers, astronauts, and airborne probes may conceivably encounter an environment where electrostatic charging is a frequent occurrence, either by way of induction from a static electric field or friction with the dusty surface and atmosphere. This raises the possibility of spark discharges or current surges when subsequent contact is made with other pieces of electrical equipment, and the possibility of damage to modern microelectronic circuitry. Measurements of electrostatic fields on the surface of Mars could therefore be valuable for assessing this danger. Electric field measurements could also be useful for detecting natural discharges that originate in dust storms. This

  10. Ion beam probing of electrostatic fields

    NASA Technical Reports Server (NTRS)

    Persson, H.

    1979-01-01

    The determination of a cylindrically symmetric, time-independent electrostatic potential V in a magnetic field B with the same symmetry by measurements of the deflection of a primary beam of ions is analyzed and substantiated by examples. Special attention is given to the requirements on canonical angular momentum and total energy set by an arbitrary, nonmonotone V, to scaling laws obtained by normalization, and to the analogy with ionospheric sounding. The inversion procedure with the Abel analysis of an equivalent problem with a one-dimensional fictitious potential is used in a numerical experiment with application to the NASA Lewis Modified Penning Discharge. The determination of V from a study of secondary beams of ions with increased charge produced by hot plasma electrons is also analyzed, both from a general point of view and with application to the NASA Lewis SUMMA experiment. Simple formulas and geometrical constructions are given for the minimum energy necessary to reach the axis, the whole plasma, and any point in the magnetic field. The common, simplifying assumption that V is a small perturbation is critically and constructively analyzed; an iteration scheme for successively correcting the orbits and points of ionization for the electrostatic potential is suggested.

  11. Electrostatics

    SciTech Connect

    Wallace, John P.; Wallace, Michael J.

    2015-12-04

    Quantum mechanics should be able to generate the basic properties of a particle. One of the most basic properties are charge and the associated electrostatic electric field. Electrostatic force is a fundamental characteristics of a charged fermion and should have its nature described by the fermion’s structure. To produce the particle properties require two spaces that define both their dynamics and their base structure. Relativity and the conservation of energy dictate how these two separate spaces are connected and the differential equations that describe behavior within these two spaces. The main static characteristic of an elementary fermion are mass and charge. Mass represents a scale measure of the fermion and it appears that charge results from the detailed structure of the fermion, which must merge into the electric field description of Maxwell. Coulomb’s law is a good approximation for large distances, but it is a poor approximation at dimension on the order of a particle’s Compton wavelength. The relativistic description of the fermion in its own frame of reference contains the information required for producing the electrostatic field over all space without a singularity as a source. With this description it is possible to understand the first order correction to the ionization energy of hydrogen. The role of nuclear effects on ionization energies can now be better defined for nuclei heavier than hydrogen.

  12. Electrostatic field between non-concentric cylinders

    SciTech Connect

    Garcia, M

    2000-01-10

    This report describes a closed-form solution to the electrostatic potential, and the electric field, between non-concentric cylinders, with the inner cylinder charged and the outer cylinder grounded. This problem is an abstraction of the situation of an electron beam within a drift tube. Capacitive and surface current probes on the inner wall of the outer cylinder are used to detect the asymmetry of the field when the beam is off center. The solution of this problem allows for a quantitative relationship between probe-array signals and beam deflection. probe-arrays of this type are called ''beam bugs'' at LLNL. The solution described here is suggested by the analysis presented in [3]. The essential point is that the 2D potential for a line source decreases along a radius as the logarithm of the distance. The non-concentric cylinder problem has a unique profile of this type for each ray from ({rho}, {sigma}) linking the inner cylinder at equipotential V{sub 2}, and the outer cylinder at equipotential 0.

  13. Orientation and transformation of flagella in electrostatic field

    SciTech Connect

    Washizu, M. ); Shikida, M. . Central Research Lab.); Aizawa, S.; Hotani, H. )

    1992-10-01

    As an extension of electrostatic molecular manipulation being developed b the authors using a high-frequency high-intensity field produce din microfabricated electrode systems, electrically induced transformation of bacterial flagella are studied. Flagella are known to assume a variety of distinct helical forms, and transformations among these polymorphic states are induced by environmental changes or by mechanical force. In this paper, the orientation time constant of flagella is first measured under the electrostatic field produced in microfabricated electrodes in order to estimate the magnitude of the induced dipole moment. Then, by further raising the field intensity, observations on the electrostatically induced transformation is made.

  14. Instability of Dielectrics and Conductors in Electrostatic Fields

    NASA Astrophysics Data System (ADS)

    Allaire, Grégoire; Rauch, Jeffrey

    2017-04-01

    This article proves most of the assertion in §116 of Maxwell's treatise on electromagnetism. The results go under the name Earnshaw's Theorem and assert the absence of stable equilibrium configurations of conductors and dielectrics in an external electrostatic field.

  15. A Solvatochromic Model Calibrates Nitriles’ Vibrational Frequencies to Electrostatic Fields

    PubMed Central

    Bagchi, Sayan; Fried, Stephen D.; Boxer, Steven G.

    2012-01-01

    Electrostatic interactions provide a primary connection between a protein’s three-dimensional structure and its function. Infrared (IR) probes are useful because vibrational frequencies of certain chemical groups, such as nitriles, are linearly sensitive to local electrostatic field, and can serve as a molecular electric field meter. IR spectroscopy has been used to study electrostatic changes or fluctuations in proteins, but measured peak frequencies have not been previously mapped to total electric fields, because of the absence of a field-frequency calibration and the complication of local chemical effects such as H-bonds. We report a solvatochromic model that provides a means to assess the H-bonding status of aromatic nitrile vibrational probes, and calibrates their vibrational frequencies to electrostatic field. The analysis involves correlations between the nitrile’s IR frequency and its 13C chemical shift, whose observation is facilitated by a robust method for introducing isotopes into aromatic nitriles. The method is tested on the model protein Ribonuclease S (RNase S) containing a labeled p-CN-Phe near the active site. Comparison of the measurements in RNase S against solvatochromic data gives an estimate of the average total electrostatic field at this location. The value determined agrees quantitatively with MD simulations, suggesting broader potential for the use of IR probes in the study of protein electrostatics. PMID:22694663

  16. A solvatochromic model calibrates nitriles' vibrational frequencies to electrostatic fields.

    PubMed

    Bagchi, Sayan; Fried, Stephen D; Boxer, Steven G

    2012-06-27

    Electrostatic interactions provide a primary connection between a protein's three-dimensional structure and its function. Infrared probes are useful because vibrational frequencies of certain chemical groups, such as nitriles, are linearly sensitive to local electrostatic field and can serve as a molecular electric field meter. IR spectroscopy has been used to study electrostatic changes or fluctuations in proteins, but measured peak frequencies have not been previously mapped to total electric fields, because of the absence of a field-frequency calibration and the complication of local chemical effects such as H-bonds. We report a solvatochromic model that provides a means to assess the H-bonding status of aromatic nitrile vibrational probes and calibrates their vibrational frequencies to electrostatic field. The analysis involves correlations between the nitrile's IR frequency and its (13)C chemical shift, whose observation is facilitated by a robust method for introducing isotopes into aromatic nitriles. The method is tested on the model protein ribonuclease S (RNase S) containing a labeled p-CN-Phe near the active site. Comparison of the measurements in RNase S against solvatochromic data gives an estimate of the average total electrostatic field at this location. The value determined agrees quantitatively with molecular dynamics simulations, suggesting broader potential for the use of IR probes in the study of protein electrostatics.

  17. Electrostatic waves in general magnetic field configurations

    SciTech Connect

    Chen, L.; Tsai, S.T.

    1981-07-01

    A scheme for investigating linear electrostatic waves in general magnetically confined plasmas is presented. The scheme is a generalization of the low-frequency (less than the cyclotron frequency) gyrokinetic formalism of Rutherford and Frieman as well as Taylor and Hastie to arbitrary frequencies. Governing integral wave equations for slab plasmas with magnetic shear as well as axisymmetric tokamaks are then derived to illustrate the applications.

  18. Role of electrostatic fields in space and astrophysical systems.

    NASA Astrophysics Data System (ADS)

    Lapenta, G.

    2005-12-01

    An unsuspected agent is emerging as a key player in a number of processes relevant to space, solar and astrophysical systems: electrostatic fields. We focus here on two processes that are present both in space and laboratory plasmas. First, we consider the formation and properties of current sheets. Current sheets are key enablers for large scale system evolution: often large scale processes lead to the formation of thin sheets where small scale processes couple with larger scales. Our recent work proposes that small scales instabilities can produce electrostatic fields on large scales with profound effects on the evolution of the system where the sheet is present. In particular, their effect can lead to the onset of reconnection. Second, a recent discovery suggests that electrostatic fields can affect the evolution of confined plasmas in laboratory experiments [2] suggesting that electrostatic fields can be a major player in magnetic dynamo processes. Our work suggests that similar processes can be also at play in space and astrophysical plasmas. We report a number of simulations that put forward a new possibility: that electrostatic fields can be a major player in processes where magnetic field energy is created (dynamo) or destroyed (reconnection). [1] W. Daughton, G. Lapenta, P. Ricci, Phys. Rev. Lett., 93, 105004, 2004 [2] D. Bonfiglio, S. Cappello, D. F. Escande, Phys. Rev. Lett., 94, 145001, 2005

  19. Points of Equilibrium in Electrostatic Fields.

    ERIC Educational Resources Information Center

    Rogers, Peter J.

    1979-01-01

    Discusses the electric field line pattern for four equal charges of the same sign placed at the corners of a square. The electric field intensity and the point of equilibrium are interpreted, taking into account three dimensions. (HM)

  20. Galactic heavy-ion shielding using electrostatic fields

    NASA Technical Reports Server (NTRS)

    Townsend, L. W.

    1984-01-01

    The shielding of spacecraft against galactic heavy ions, particularly high-energy Fe(56) nuclei, by electrostatic fields is analyzed for an arrangement of spherical concentric shells. Vacuum breakdown considerations are found to limit the minimum radii of the spheres to over 100 m. This limitation makes it impractical to use the fields for shielding small spacecraft. The voltages necessary to repel these Fe(56) nuclei exceed present electrostatic generating capabilities by over 2 orders of magnitude and render the concept useless as an alternative to traditional bulk-material shielding methods.

  1. Magnetic and electrostatic confinement of plasma with tuning of electrostatic field

    DOEpatents

    Rostoker, Norman; Binderbauer, Michl; Qerushi, Artan; Tahsiri, Hooshang

    2006-10-10

    A system and method for containing plasma and forming a Field Reversed Configuration (FRC) magnetic topology are described in which plasma ions are contained magnetically in stable, non-adiabatic orbits in the FRC. Further, the electrons are contained electrostatically in a deep energy well, created by tuning an externally applied magnetic field. The simultaneous electrostatic confinement of electrons and magnetic confinement of ions avoids anomalous transport and facilitates classical containment of both electrons and ions. In this configuration, ions and electrons may have adequate density and temperature so that upon collisions they are fused together by nuclear force, thus releasing fusion energy. Moreover, the fusion fuel plasmas that can be used with the present confinement system and method are not limited to neutronic fuels only, but also advantageously include advanced fuels.

  2. Magnetic and electrostatic confinement of plasma with tuning of electrostatic field

    DOEpatents

    Rostoker, Norman; Binderbauer, Michl; Qerushi, Artan; Tahsiri, Hooshang

    2006-03-21

    A system and method for containing plasma and forming a Field Reversed Configuration (FRC) magnetic topology are described in which plasma ions are contained magnetically in stable, non-adiabatic orbits in the FRC. Further, the electrons are contained electrostatically in a deep energy well, created by tuning an externally applied magnetic field. The simultaneous electrostatic confinement of electrons and magnetic confinement of ions avoids anomalous transport and facilitates classical containment of both electrons and ions. In this configuration, ions and electrons may have adequate density and temperature so that upon collisions they are fused together by nuclear force, thus releasing fusion energy. Moreover, the fusion fuel plasmas that can be used with the present confinement system and method are not limited to neutronic fuels only, but also advantageously include advanced fuels.

  3. Magnetic and electrostatic confinement of plasma with tuning of electrostatic field

    DOEpatents

    Rostoker, Norman; Binderbauer, Michl; Qerushi, Artan; Tahsiri, Hooshang

    2008-10-21

    A system and method for containing plasma and forming a Field Reversed Configuration (FRC) magnetic topology are described in which plasma ions are contained magnetically in stable, non-adiabatic orbits in the FRC. Further, the electrons are contained electrostatically in a deep energy well, created by tuning an externally applied magnetic field. The simultaneous electrostatic confinement of electrons and magnetic confinement of ions avoids anomalous transport and facilitates classical containment of both electrons and ions. In this configuration, ions and electrons may have adequate density and temperature so that upon collisions they are fused together by nuclear force, thus releasing fusion energy. Moreover, the fusion fuel plasmas that can be used with the present confinement system and method are not limited to neutronic fuels only, but also advantageously include advanced fuels.

  4. Intermediate electrostatic field for the generalized elongation method.

    PubMed

    Liu, Kai; Korchowiec, Jacek; Aoki, Yuriko

    2015-05-18

    An intermediate electrostatic field is introduced to improve the accuracy of fragment-based quantum-chemical computational methods by including long-range polarizations of biomolecules. The point charge distribution of the intermediate field is generated by a charge sensitivity analysis that is parameterized for five different population analyses, namely, atoms-in-molecules, Hirshfeld, Mulliken, natural orbital, and Voronoi population analysis. Two model systems are chosen to demonstrate the performance of the generalized elongation method (ELG) combined with the intermediate electrostatic field. The calculations are performed for the STO-3G, 6-31G, and 6-31G(d) basis sets and compared with reference Hartree-Fock calculations. It is shown that the error in the total energy is reduced by one order of magnitude, independently of the population analyses used. This demonstrates the importance of long-range polarization in electronic-structure calculations by fragmentation techniques.

  5. Electrostatic acceleration of helicon plasma using a cusped magnetic field

    SciTech Connect

    Harada, S.; Baba, T.; Uchigashima, A.; Iwakawa, A.; Sasoh, A.; Yokota, S.; Yamazaki, T.; Shimizu, H.

    2014-11-10

    The electrostatic acceleration of helicon plasma is investigated using an electrostatic potential exerted between the ring anode at the helicon source exit and an off-axis hollow cathode in the downstream region. In the downstream region, the magnetic field for the helicon source, which is generated by a solenoid coil, is modified using permanent magnets and a yoke, forming an almost magnetic field-free region surrounded by an annular cusp field. Using a retarding potential analyzer, two primary ion energy peaks, where the lower peak corresponds to the space potential and the higher one to the ion beam, are detected in the field-free region. Using argon as the working gas with a helicon power of 1.5 kW and a mass flow rate of 0.21 mg/s, the ion beam energy is on the order of the applied acceleration voltage. In particular, with an acceleration voltage lower than 150 V, the ion beam energy even exceeds the applied acceleration voltage by an amount on the order of the electron thermal energy at the exit of the helicon plasma source. The ion beam energy profile strongly depends on the helicon power and the applied acceleration voltage. Since by this method the whole working gas from the helicon plasma source can, in principle, be accelerated, this device can be applied as a noble electrostatic thruster for space propulsion.

  6. Trapping and manipulating neutral atoms with electrostatic fields.

    PubMed

    Krüger, P; Luo, X; Klein, M W; Brugger, K; Haase, A; Wildermuth, S; Groth, S; Bar-Joseph, I; Folman, R; Schmiedmayer, J

    2003-12-05

    We report on experiments with cold thermal (7)Li atoms confined in combined magnetic and electric potentials. A novel type of three-dimensional trap was formed by modulating a magnetic guide using electrostatic fields. We observed atoms trapped in a string of up to six individual such traps, a controlled transport of an atomic cloud over a distance of 400 microm, and a dynamic splitting of a single trap into a double well potential. Applications for quantum information processing are discussed.

  7. Calculation of electrostatic fields in periodic structures of complex shape

    NASA Technical Reports Server (NTRS)

    Kravchenko, V. F.

    1978-01-01

    A universal algorithm is presented for calculating electrostatic fields in an infinite periodic structure consisting of electrodes of arbitrary shape which are located in mirror-symmetrical manner along the axis of electron-beam propagation. The method is based on the theory of R-functions, and the differential operators which are derived on the basis of the functions. Numerical results are presented and the accuracy of the results is examined.

  8. Electrostatic field around cytochrome c: theory and energy transfer experiment.

    PubMed

    Northrup, S H; Wensel, T G; Meares, C F; Wendoloski, J J; Matthew, J B

    1990-12-01

    Energy transfer in the "rapid diffusion" limit from electronically excited terbium(III) chelates in three different charge states to horse heart ferricytochrome c was measured as a function of ionic strength. Theoretical rate constants calculated by numerical integration of the Forster integral (containing the Poisson-Boltzmann-generated protein electrostatic potential) were compared with the experimental data to evaluate the accuracy of protein electrostatic field calculations at the protein/solvent interface. Two dielectric formalisms were used: a simple coulombic/Debye-Hückel procedure and a finite difference method [Warwicker, J. & Watson, H. C. (1982) J. Mol. Biol. 157, 671-679] that accounts for the low-dielectric protein interior and the irregular protein/solvent boundary. Good agreement with experiment was obtained and the ionic-strength dependence of the reaction was successfully reproduced. The sensitivity of theoretical rate constants to the choices of effective donor sphere size and the energy transfer distance criterion was analyzed. Electrostatic potential and rate-constant calculations were carried out on sets of structures collected along two molecular dynamics trajectories of cytochrome c. Protein conformational fluctuations were shown to produce large variations in the calculated energy transfer rate constant. We conclude that protein fluctuations and the resulting transient structures can play significant roles in biological or catalytic activities that are not apparent from examination of a static structure. For calculating protein electrostatics, large-scale low-frequency conformational fluctuations, such as charged side-chain reorientation, are established to be as important as the computational method for incorporating dielectric boundary effects.

  9. Development of installation for study of electrostatic fields

    NASA Astrophysics Data System (ADS)

    Kyrmakova, O. S.; Skoryupina, K. A.; Sechin, A. I.

    2017-08-01

    The safe installation for studying the model electrostatic fields in the model areas of the cyclone is developed. It is found that the induction neutralizer reduces the concentration of ethyl alcohol (ethanol) in the examined object. The distance between the charged region in the cyclone and the neutralizer is the correction value of the height of the corona needles that is characterized by the magnitude of the ignition energy of the medium in the cyclone. The research results can be used in the development of cyclone apparatus for explosive industries, as well as measures to reduce technological emissions into the environment.

  10. Understanding and Manipulating Electrostatic Fields at the Protein-Protein Interface Using Vibrational Spectroscopy and Continuum Electrostatics Calculations.

    PubMed

    Ritchie, Andrew W; Webb, Lauren J

    2015-11-05

    Biological function emerges in large part from the interactions of biomacromolecules in the complex and dynamic environment of the living cell. For this reason, macromolecular interactions in biological systems are now a major focus of interest throughout the biochemical and biophysical communities. The affinity and specificity of macromolecular interactions are the result of both structural and electrostatic factors. Significant advances have been made in characterizing structural features of stable protein-protein interfaces through the techniques of modern structural biology, but much less is understood about how electrostatic factors promote and stabilize specific functional macromolecular interactions over all possible choices presented to a given molecule in a crowded environment. In this Feature Article, we describe how vibrational Stark effect (VSE) spectroscopy is being applied to measure electrostatic fields at protein-protein interfaces, focusing on measurements of guanosine triphosphate (GTP)-binding proteins of the Ras superfamily binding with structurally related but functionally distinct downstream effector proteins. In VSE spectroscopy, spectral shifts of a probe oscillator's energy are related directly to that probe's local electrostatic environment. By performing this experiment repeatedly throughout a protein-protein interface, an experimental map of measured electrostatic fields generated at that interface is determined. These data can be used to rationalize selective binding of similarly structured proteins in both in vitro and in vivo environments. Furthermore, these data can be used to compare to computational predictions of electrostatic fields to explore the level of simulation detail that is necessary to accurately predict our experimental findings.

  11. Electrostatic ion-cyclotron waves in a nonuniform magnetic field

    NASA Technical Reports Server (NTRS)

    Cartier, S. L.; Dangelo, N.; Merlino, R. L.

    1985-01-01

    The properties of electrostatic ion-cyclotron waves excited in a single-ended cesium Q machine with a nonuniform magnetic field are described. The electrostatic ion-cyclotron waves are generated in the usual manner by drawing an electron current to a small exciter disk immersed in the plasma column. The parallel and perpendicular (to B) wavelengths and phase velocities are determined by mapping out two-dimensional wave phase contours. The wave frequency f depends on the location of the exciter disk in the nonuniform magnetic field, and propagating waves are only observed in the region where f is approximately greater than fci, where fci is the local ion-cyclotron frequency. The parallel phase velocity is in the direction of the electron drift. From measurements of the plasma properties along the axis, it is inferred that the electron drift velocity is not uniform along the entire current channel. The evidence suggests that the waves begin being excited at that axial position where the critical drift velocity is first exceeded, consistent with a current-driven excitation mechanism.

  12. Physical electrostatics of small field emitter arrays/clusters

    NASA Astrophysics Data System (ADS)

    Forbes, Richard G.

    2016-08-01

    This paper aims to improve qualitative understanding of electrostatic influences on apex field enhancement factors (AFEFs) for small field emitter arrays/clusters. Using the "floating sphere at emitter-plate potential" (FSEPP) model, it re-examines the electrostatics and mathematics of three simple systems of identical post-like emitters. For the isolated emitter, various approaches are noted. An adequate approximation is to consider only the effects of sphere charges and (for significantly separated emitters) image charges. For the 2-emitter system, formulas are found for charge-transfer ("charge-blunting") effects and neighbor-field effects, for widely spaced and for "sufficiently closely spaced" emitters. Mutual charge-blunting is always the dominant effect, with a related (negative) fractional AFEF-change δtwo. For sufficiently small emitter spacing c, |δtwo| varies approximately as 1/c; for large spacing, |δtwo| decreases as 1/c3. In a 3-emitter equispaced linear array, differential charge-blunting and differential neighbor-field effects occur, but differential charge-blunting effects are dominant, and cause the "exposed" outer emitters to have higher AFEF (γ0) than the central emitter (γ1). Formulas are found for the exposure ratio Ξ = γ0/γ1, for large and for sufficiently small separations. The FSEPP model for an isolated emitter has accuracy around 30%. Line-charge models (LCMs) are an alternative, but an apparent difficulty with recent LCM implementations is identified. Better descriptions of array electrostatics may involve developing good fitting equations for AFEFs derived from accurate numerical solution of Laplace's equation, perhaps with equation form(s) guided qualitatively by FSEPP-model results. In existing fitting formulas, the AFEF-reduction decreases exponentially as c increases, which is different from the FSEPP-model formulas. This discrepancy needs to be investigated, using systematic Laplace-based simulations and appropriate results

  13. Tailoring nanoscale morphology of polymer: Fullerene blends using electrostatic field

    DOE PAGES

    Elshobaki, Moneim; Gebhardt, Ryan; Carr, John; ...

    2016-12-05

    In this paper, to tailor the nanoscale phase separation in polymer/fullerene blends, we study the effect of electrostatic field (E-field) on the solidification of poly(3-hexylthiophene-2, 5-diyl) (P3HT):[6,6]-phenyl-C61-butyric acid methyl ester (PC60BM) bulk heterojunction (BHJ). In addition to untreated sample (control); wet P3HT:PC60BM thin films were exposed to E-field of Van de Graaff (VDG) generator at three different directions – horizontal (H), tilted (T) and vertical (V) – relative to the plane of the substrate. Surface and bulk characterizations of field-treated BHJs affirm that fullerene molecules can easily penetrate the spaghetti-like P3HT and move up and down following the E-field. E-fieldmore » treatment yields thin films with large P3HT- and PCBM-rich domains acting as continuous pathways for efficient charge separation, transport, and collection. We improve; (1) the hole mobility values up to 19.4 × 10-4 ± 1.6 × 10-4 cm2 V-1 s-1 (117% higher than the control), and (2) power conversion efficient (PCE) of conventional and inverted OPVs recording 2.58 ± 0.02% and 4.1 ± 0.4%. This E-field approach can serve as a new morphology-tuning technique, which is generally applicable to other polymer-fullerene systems.« less

  14. Modification of the lower ionospheric conductivity by thunderstorm electrostatic fields

    NASA Astrophysics Data System (ADS)

    Salem, Mohammad A.; Liu, Ningyu; Rassoul, Hamid K.

    2016-01-01

    This paper reports a modeling study of the modifications of the nighttime lower ionospheric conductivity by electrostatic fields produced by underlying thunderstorms. The model used combines Ohm's law with a simplified lower ionospheric ion chemistry model to self-consistently calculate the steady state nighttime conductivity above a thunderstorm. The results indicate that although the electron density is generally increased, the lower ionospheric conductivity can be reduced by up to 1-2 orders of magnitude because electron mobility is significantly reduced due to the electron heating effect. For a typical ionospheric density profile, the resulting changes in the reflection heights of extremely low frequency and very low frequency waves are 5 and 2 km, respectively.

  15. On the response of large systems to electrostatic fields

    SciTech Connect

    Springborg, Michael; Kirtman, Bernard

    2015-01-22

    By modifying the surfaces of a macroscopic regular system it is possible to modify the dipole moment per unit by an amount equal to a lattice vector times the elementary charge. Alternatively, we may ignore the surfaces and treat the system as being infinite and periodic. In that event the dipole moment per unit is determined only up to an additive term equal to a lattice vector times the elementary charge. Beyond mathematical arguments we show, through model calculations, that the two cases are completely equivalent, even though the origin of the additive term is very different. The response of extended systems to electrostatic fields — including internal structure, piezoelectricity, bulk charge density, and (hyper)polarizabilities — depends upon this term and is, thereby, surface-dependent. The case of piezoelectricity is analyzed in some detail.

  16. Electrostatic ion acceleration across a diverging magnetic field

    SciTech Connect

    Ichihara, D. Uchigashima, A.; Iwakawa, A.; Sasoh, A.

    2016-08-01

    Electrostatic ion acceleration across a diverging magnetic field, which is generated by a solenoid coil, permanent magnets, and a yoke between an upstream ring anode and a downstream off-axis hollow cathode, is investigated. The cathode is set in an almost magnetic-field-free region surrounded by a cusp. Inside the ring anode, an insulating wall is set to form an annular slit through which the working gas is injected along the anode inner surface, so the ionization of the working gas is enhanced there. By supplying 1.0 Aeq of argon as working gas with a discharge voltage of 225 V, the ion beam energy reached about 60% of a discharge voltage. In spite of this unique combination of electrodes and magnetic field, a large electrical potential drop is formed almost in the axial direction, located slightly upstream of the magnetic-field-free region. The ion beam current almost equals the equivalent working gas flow rate. These ion acceleration characteristics are useful for electric propulsion in space.

  17. Electrostatic ion acceleration across a diverging magnetic field

    NASA Astrophysics Data System (ADS)

    Ichihara, D.; Uchigashima, A.; Iwakawa, A.; Sasoh, A.

    2016-08-01

    Electrostatic ion acceleration across a diverging magnetic field, which is generated by a solenoid coil, permanent magnets, and a yoke between an upstream ring anode and a downstream off-axis hollow cathode, is investigated. The cathode is set in an almost magnetic-field-free region surrounded by a cusp. Inside the ring anode, an insulating wall is set to form an annular slit through which the working gas is injected along the anode inner surface, so the ionization of the working gas is enhanced there. By supplying 1.0 Aeq of argon as working gas with a discharge voltage of 225 V, the ion beam energy reached about 60% of a discharge voltage. In spite of this unique combination of electrodes and magnetic field, a large electrical potential drop is formed almost in the axial direction, located slightly upstream of the magnetic-field-free region. The ion beam current almost equals the equivalent working gas flow rate. These ion acceleration characteristics are useful for electric propulsion in space.

  18. Theory and simulations of electrostatic field error transport

    SciTech Connect

    Dubin, Daniel H. E.

    2008-07-15

    Asymmetries in applied electromagnetic fields cause plasma loss (or compression) in stellarators, tokamaks, and non-neutral plasmas. Here, this transport is studied using idealized simulations that follow guiding centers in given fields, neglecting collective effects on the plasma evolution, but including collisions at rate {nu}. For simplicity the magnetic field is assumed to be uniform; transport is due to asymmetries in applied electrostatic fields. Also, the Fokker-Planck equation describing the particle distribution is solved, and the predicted transport is found to agree with the simulations. Banana, plateau, and fluid regimes are identified and observed in the simulations. When separate trapped particle populations are created by application of an axisymmetric squeeze potential, enhanced transport regimes are observed, scaling as {radical}({nu}) when {nu}<{omega}{sub 0}<{omega}{sub B} and as 1/{nu} when {omega}{sub 0}<{nu}<{omega}{sub B} (where {omega}{sub 0} and {omega}{sub B} are the rotation and axial bounce frequencies, respectively). These regimes are similar to those predicted for neoclassical transport in stellarators.

  19. Control of Flowing Liquid Films By Electrostatic Fields in Space

    NASA Technical Reports Server (NTRS)

    Bankoff, S. George; Miksis, Michael J.; Kim, Hyo

    1996-01-01

    A novel type of lightweight space radiator has been proposed which employs internal electrostatic fields to stop coolant leaks from punctures caused by micrometeorites or space debris. Extensive calculations have indicated the feasibility of leak stoppage without film destabilization for both stationary and rotating designs. Solutions of the evolution equation for a liquid-metal film on an inclined plate, using lubrication theory for low Reynolds numbers, Karman-Pohlhausen quadratic velocity profiles for higher Reynolds numbers, and a direct numerical solution are shown. For verification an earth-based falling-film experiment on a precisely-vertical wall with controllable vacuum on either side of a small puncture is proposed. The pressure difference required to start and to stop the leak, in the presence and absence of a strong electric field, will be measured and compared with calculations. Various parameters, such as field strength, film Reynolds number, contact angle, and hole diameter will be examined. A theoretical analysis will be made of the case where the electrode is close enough to the film surface that the electric field equation and the surface dynamics equations are coupled. Preflight design calculations will be made in order to transfer the modified equipment to a flight experiment.

  20. Tailoring nanoscale morphology of polymer: Fullerene blends using electrostatic field

    SciTech Connect

    Elshobaki, Moneim; Gebhardt, Ryan; Carr, John; Lindemann, William; Wang, Wenjie; Grieser, Eric; Venkatesan, Swaminathan; Ngo, Evan; Bhattacharjee, Ujjal; Strzalka, Joseph; Jiang, Zhang; Qiao, Qiquan; Petrich, Jacob; Vaknin, David; Chaudhary, Sumit

    2016-12-05

    In this paper, to tailor the nanoscale phase separation in polymer/fullerene blends, we study the effect of electrostatic field (E-field) on the solidification of poly(3-hexylthiophene-2, 5-diyl) (P3HT):[6,6]-phenyl-C61-butyric acid methyl ester (PC60BM) bulk heterojunction (BHJ). In addition to untreated sample (control); wet P3HT:PC60BM thin films were exposed to E-field of Van de Graaff (VDG) generator at three different directions – horizontal (H), tilted (T) and vertical (V) – relative to the plane of the substrate. Surface and bulk characterizations of field-treated BHJs affirm that fullerene molecules can easily penetrate the spaghetti-like P3HT and move up and down following the E-field. E-field treatment yields thin films with large P3HT- and PCBM-rich domains acting as continuous pathways for efficient charge separation, transport, and collection. We improve; (1) the hole mobility values up to 19.4 × 10-4 ± 1.6 × 10-4 cm2 V-1 s-1 (117% higher than the control), and (2) power conversion efficient (PCE) of conventional and inverted OPVs recording 2.58 ± 0.02% and 4.1 ± 0.4%. This E-field approach can serve as a new morphology-tuning technique, which is generally applicable to other polymer-fullerene systems.

  1. The low-field permanent magnet electrostatic plasma lens

    NASA Astrophysics Data System (ADS)

    Goncharov, A.; Gorshkov, V.; Maslov, V.; Zadorozhny, V.; Brown, I.

    2004-05-01

    We describe the status of ongoing research and development of the electrostatic plasma lens as used for the manipulation of high current broad beams of heavy ions of moderate energy. In some collaborative work at Lawrence Berkeley National Laboratory the lens was used to good effect for carrying out high dose ion implantation processing. In the process of this work a very narrow range of low magnetic field was found for which the ion-optical characteristics of the lens improved markedly. Subsequent theoretical analysis and computer modeling has led to an understanding of this phenomenon. These serendipitous results open up some attractive possibilities for the development of a new compact and low cost plasma lens based on permanent magnets rather than on current-driven field coils surrounding the lens volume. The development of this kind of lens, including both very low noise and minimal spherical aberration effects, may lead to a tool suitable for use in the injection beam lines of high current heavy ion linear accelerators. Here we briefly review the lens fundamentals, some characteristics of focusing heavy ion beams at low magnetic fields, and summarize recent theoretical and experimental developments, with emphasis on the relevance and suitability of the lens for accelerator injection application.

  2. Electrostatic field changes and durations of narrow bipolar events

    NASA Astrophysics Data System (ADS)

    Karunarathne, S.; Marshall, T. C.; Stolzenburg, M.; Karunarathna, N.

    2016-09-01

    Using an array of 10 sensors, electric field change measurements of 35 positive narrow bipolar events (NBEs) were obtained at close range (≤10 km). At the closest sensor all 35 NBEs had a net electrostatic change (ΔEfast) associated with the main bipolar pulse with amplitudes of 0.4 to 16.3 V/m (not range normalized). At the closest sensor the bipolar pulse of each of the 35 NBEs was followed by a relatively long, slow electrostatic change (ΔEslow) with amplitudes of 0.1 to 43.4 V/m and durations of 0.7 to 33.7 ms. For ΔEfast, estimated 3-D charge moments for 10 NBEs ranged from 0.46 C km to 1.81 C km with an average and standard deviation of (1.09 ± 0.36) C km. Seven 3-D charge moments were essentially vertically oriented, and the other three moments were tilted at 10°-20° from vertical. The 10 3-D charge moments were overlaid on vertical radar cross sections; 6 NBEs occurred in weak reflectivity near the upper reflectivity boundary; the other 4 NBEs occurred near the top of the high-reflectivity core of the thunderclouds. For ΔEslow, we estimated 3-D charge moments for only three NBEs; they ranged from 1.11 C km to 2.69 C km with an average of (1.83 ± 0.80) C km. A two current transmission line model matched the bipolar pulse and the following slow change (ΔEslow) of one NBE reasonably well. The slow change mechanism may be different from the NBE mechanism and similar to the initial E-change before typical lightning flashes.

  3. Hohenberg-Kohn theorems in electrostatic and uniform magnetostatic fields

    SciTech Connect

    Pan, Xiao-Yin; Sahni, Viraht

    2015-11-07

    The Hohenberg-Kohn (HK) theorems of bijectivity between the external scalar potential and the gauge invariant nondegenerate ground state density, and the consequent Euler variational principle for the density, are proved for arbitrary electrostatic field and the constraint of fixed electron number. The HK theorems are generalized for spinless electrons to the added presence of an external uniform magnetostatic field by introducing the new constraint of fixed canonical orbital angular momentum. Thereby, a bijective relationship between the external scalar and vector potentials, and the gauge invariant nondegenerate ground state density and physical current density, is proved. A corresponding Euler variational principle in terms of these densities is also developed. These theorems are further generalized to electrons with spin by imposing the added constraint of fixed canonical orbital and spin angular momenta. The proofs differ from the original HK proof and explicitly account for the many-to-one relationship between the potentials and the nondegenerate ground state wave function. A Percus-Levy-Lieb constrained-search proof expanding the domain of validity to N-representable functions, and to degenerate states, again for fixed electron number and angular momentum, is also provided.

  4. Investigation of the Arcjet near Field Plume Using Electrostatic Probes

    NASA Technical Reports Server (NTRS)

    Sankovic, John M.

    1990-01-01

    The near field plume of a 1 kW class arcjet thruster was investigated using electrostatic probes of various geometries. The electron number densities and temperatures were determined in a simulated hydrazine plume at axial distances between 3 cm (1.2 in.) and 15 cm (5.9 in.) and radial distances extending to 10 cm (3.9 in.) off centerline. Values of electron number densities obtained using cylindrical and spherical probes of different geometries agreed very well. The electron density on centerline followed a source flow approximation for axial distances as near as 3 cm (1.2 in.) from the nozzle exit plane. The model agreed well with previously obtained data in the far field. The effects of propellant mass flow rate and input power level were also studied. Cylindrical probes were used to obtain ion streamlines by changing the probe orientation with respect to the flow. The effects of electrical configuration on the plasma characteristics of the plume were also investigated by using a segmented anode/nozzle thruster. The results showed that the electrical configuration in the nozzle affected the distribution of electrons in the plume.

  5. Investigation of the arcjet plume near field using electrostatic probes

    NASA Technical Reports Server (NTRS)

    Sankovic, John M.

    1990-01-01

    The near field plum of a 1 kW class arcjet thruster was investigated using electrostatic probes of various geometries. The electron number densities and temperatures were determined in a simulated hydrazine plume at axial distances between 3 cm (1.2 in) and 15 cm (5.9 in) and radial distances extending to 10 cm (3.9 in) off centerline. Values of electron number densities obtained using cylindrical and spherical probes of different geometries agreed very well. The electron density on centerline followed a source flow approximation for axial distances as near as 3 cm (1.2 in) from the nozzle exit plane. The model agreed well with previously obtained data in the far field. The effects of propellant mass flow rate and input power level were also studied. Cylindrical probes were used to obtain ion streamlines by changing the probe orientation with respect to the flow. The effects of electrical configuration on the plasma characteristics of the plume were also investigated by using a segmented anode/nozzle thruster. The results showed that the electrical configuration in the nozzle affected the distribution of electrons in the plume.

  6. Heterogeneous mass transfer in HRE in the presence of electrostatic field research

    NASA Astrophysics Data System (ADS)

    Reshetnikov, S. M.; Zyryanov, I. A.; Budin, A. G.; Pozolotin, A. P.

    2017-01-01

    The paper presents research results of polymethylmethacrylate (PMMA) combustion in a hybrid rocket engine (HRE) under the influence of an electrostatic field. It is shown that the main mechanism of electrostatic field influence on the combustion rate is process changes in the condensed phase.

  7. Proton imaging of an electrostatic field structure formed in laser-produced counter-streaming plasmas

    NASA Astrophysics Data System (ADS)

    Morita, T.; Kugland, N. L.; Wan, W.; Crowston, R.; Drake, R. P.; Fiuza, F.; Gregori, G.; Huntington, C.; Ishikawa, T.; Koenig, M.; Kuranz, C.; Levy, M. C.; Martinez, D.; Meinecke, J.; Miniati, F.; Murphy, C. D.; Pelka, A.; Plechaty, C.; Presura, R.; Quirós, N.; Remington, B. A.; Reville, B.; Ross, J. S.; Ryutov, D. D.; Sakawa, Y.; Steele, L.; Takabe, H.; Yamaura, Y.; Woolsey, N.; Park, H.-S.

    2016-03-01

    We report the measurements of electrostatic field structures associated with an electrostatic shock formed in laser-produced counter-streaming plasmas with proton imaging. The thickness of the electrostatic structure is estimated from proton images with different proton kinetic energies from 4.7 MeV to 10.7 MeV. The width of the transition region is characterized by electron scale length in the laser-produced plasma, suggesting that the field structure is formed due to a collisionless electrostatic shock.

  8. Correlation of electrostatic fluctuation and reversal of toroidal field in the reversed-field pinch plasma

    SciTech Connect

    Yambe, Kiyoyuki; Koguchi, Haruhisa; Sakakita, Hajime; Hirano, Yoichi; Kiyama, Satoru

    2011-06-15

    The magnetic fluctuations and electrostatic probe potential have been measured in the Toroidal Pinch Experiment - RX (TPE-RX) reversed-field pinch plasma [Y. Yagi et al., Fusion Eng. Des. 45, 421 (1999)] (at the plasma surface r/a = 1.00). Fast electrons with energy comparable to or slightly higher than the core electron temperature are observed as many spikes in the electrostatic probe signal. These electrons are diffused by a fluctuating magnetic field from the core region. During the period of mild deepening of the reversal of the edge toroidal field, a significant reduction in the spike signal, increases in electron density and soft x-ray radiation, and a decrease in the D{alpha} line radiation are observed, even though the reduction in magnetic fluctuations is not significant during the same period, which indicates that the mild deepening of the reversal of the toroidal field can improve the confinement of fast electrons.

  9. Electrostatic Field Influence on Luminescence Features of Cadmium Sulphide Quantum Dots in Silica Matrix

    NASA Astrophysics Data System (ADS)

    Voznesenskiy, S. S.; Sergeev, A. A.; Postnova, I. V.; Shchipunov, Y. A.

    The effect of electrostatic field on optical properties of silicate nanocomposite with cadmium sulfide quantum dots was investigated. It was found that the electrostatic field causes quantum dot orientation along the field force lines leading to changes in the polarized components of the luminescence spectrum. The influence of field force line direction on photoinduced absorption characteristics arised from λ = 405.9 nm laser radiation exposure to nanocomposite was shown.

  10. Modelling Electrostatic Sheath Effects on Swarm Electric Field Instrument Measurements

    NASA Astrophysics Data System (ADS)

    Marchand, R.; Burchill, J. K.; Knudsen, D. J.

    2010-10-01

    The Electric Field Instrument (EFI) was designed to measure ionospheric ion flow velocities, temperatures and distribution functions at the ram face of the European Space Agency’s Swarm spacecraft. These flow velocities, combined with the known orbital velocity of the satellite and local magnetic field, will be used to infer local electric fields from the relation E=- v× B. EFI is among a class of many particle sensors and flow meters mounted on satellites to monitor in situ plasma conditions. The interpretation of the measurements made with EFI and similar sensors relies on a spacecraft sheath model. A common approach, valid in the relatively cold and dense ionospheric plasma, is to assume a potential drop in a thin sheath through which particle deflection and energisation can be calculated analytically. In such models, sheath effects only depend on the spacecraft floating potential, and on the angle of incidence of particles with respect to the normal to the surface. Corrections to measurements are therefore local as they do not depend on the geometry of nearby objects. In an actual plasma, satellites are surrounded by electrostatic sheaths with a finite thickness. As a result, local corrections to particle distribution functions can only be seen as an approximation. A correct interpretation of measured particle fluxes or particle distribution functions must, at least in principle, account for the extent and shape of the sheath in the vicinity of the measuring instrument. This in turn requires a careful analysis of the interaction of the satellite with the surrounding plasma, while accounting for detailed aspects of the geometry, as well as for several physical effects. In this paper, the validity of the thin sheath model is tested by comparing its predictions with detailed PIC (Particle In Cell) calculations of satellite-plasma interaction. Deviations attributed to sheath finite thickness effects are calculated for EFI measurements, with representative plasma

  11. Accurate color tuning of firefly chromophore by modulation of local polarization electrostatic fields.

    PubMed

    Cai, Duanjun; Marques, Miguel A L; Nogueira, Fernando

    2011-01-20

    Although many microenvironmental factors contribute to the color shift of light emission from the firefly chromophore, the dominant one is the local electrostatic field. This opens up the possibility of accurate color tuning the bioluminescent absorption and emission by adjusting the local charged residues. With this aim, the optical response of oxyluciferin for different electrostatic fields is computed by using time-dependent density-functional theory. We find that the wavelength shift is correlated to the projection of the electrostatic field on the molecular plane, and that the fluorescent intensity of the second excitation peak can be effectively enhanced or suppressed (±30%) by field modulation. A model is formulated by correlating the shift in the spectral maxima with the projection of the local electrostatic field on the molecular plane. This method provides a predictable determination of the structural modifications leading to a particular color shift and/or fluorescent efficiency enhancement.

  12. Electrostatic discharge and field effects of electronics systems

    NASA Astrophysics Data System (ADS)

    Dicks, L. R.; Morin, G.

    1988-04-01

    The effects of static electricity on modern electronics are discussed, as well as a comprehensive approach to electrostatic discharge (ESD) protection measures in all phases of the life cycle of an electronic system. Static electricity has become a potential source of damage to electronic systems used in most applications, including aircraft, ground and shipboard installations.

  13. Enhancing molecular orientation by combining electrostatic and four-color laser fields

    NASA Astrophysics Data System (ADS)

    Xu, Shuwu; Yao, Yunhua; Lu, Chenhui; Jia, Tianqing; Ding, Jingxin; Zhang, Shian; Sun, Zhenrong

    2014-09-01

    We propose a scheme to enhance molecular orientation by combing an intense electrostatic field and a four-color laser field. We show that molecular orientation by the combined field can be obtained under a laser-field-free condition, and the maximal orientation degree can be enhanced by comparing with the sum of that individually created by the electrostatic field and the four-color laser field. Our results show that the orientation enhancement results from the larger asymmetry of the four-color laser field because of the existence of the electrostatic field. Furthermore, we also discuss the dependence of the orientation enhancement on the carrier-envelope phase, laser intensity, and pulse duration of the four-color laser field and the molecular rotational temperature.

  14. Effects of interaction between plasma-flow fields and electrostatic fields in dusty plasmas

    NASA Astrophysics Data System (ADS)

    Tsytovich, V. N.

    2007-04-01

    Interaction between plasma-flow fields and electrostatic fields is considered as the most appropriate method for describing the characteristic properties of a dusty plasma. This method makes it possible to treat the openness of the dusty plasma systems and to describe the processes of self-organization and change in interaction between dust particles that are caused by the presence of plasma flows, in particular, to describe attraction between the dust particles at large distances, as well as the pairing of identically charged particles and the formation of complicated dusty structures including dusty plasma crystals. Interaction between the plasma-flow fields and electrostatic fields was previously taken into account only when considering particular problems but was not considered as the general characteristic property of the dusty plasma. It is emphasized that the model taking into account the plasma-flow fields and their interaction with the electrostatic fields is the only model that allows simultaneous explanation of all basic parameters characterizing the condensation of the dusty plasma to plasma crystals (coupling constant Γ, interparticle distance r min, and melting temperature T d) obtained in observations. Attraction between the dust particles at large distances leads to instability similar to gravitational instability, which was erroneously disregarded in previous descriptions of the dust sound. The corresponding critical size is similar to the Jeans radius. As a result of such attraction, dusty systems are structured, and such structuring is similar to known gravitational structuring and can explain the observation of dusty structures in most laboratory experiments on the dusty plasma.

  15. The effect of an electrostatic field on film flow down an inclined plane

    SciTech Connect

    Kim, H.; Bankoff, S.G. ); Miksis, M.J. )

    1992-10-01

    A study of the interaction of an electrostatic field with a thin liquid film flowing under gravity down an inclined plane is presented. First, the effect of the electric field on the stability of the film flow is examined. Next, several limits of the equations of motion are investigated analytically, and then compared with an explicit numerical calculation of the equations of motion. Also, applications of these calculations to a proposed electrostatic liquid film space radiator are discussed.

  16. MHD dynamo in Reversed Field Pinch Plasmas: electrostatic drift nature of the dynamo velocity field

    NASA Astrophysics Data System (ADS)

    Cappello, Susanna

    2005-10-01

    Within the framework of MHD numerical modelling, the Reversed Field Pinch (RFP) has been found to develop turbulent or laminar regimes switching from the former to the latter in a continuous way depending on the strength of dissipative forces. The laminar solution corresponds to a simple global helical deformation of the current channel and is associated to an electrostatic dynamo field. In this work we show that the associated drift yields the main component of the dynamo velocity. While quite natural in the stationary helical state, this analysis is shown to extend also to the dynamic turbulent regime for a sustained RFP. The continuity of the transition between the two regimes suggests that the simple helical symmetric solution can provide a fruitful intuitive description of the RFP dynamo in general. Many of the MHD predictions are in good agreement with experimental findings. References: [1] S. Cappello and D.F. Escande, ``Bifurcation in viscoresistive MHD: the Hartmann number and the RFP,'' Phys. Rev. Lett. 85, 3838 (2000) [2] S. Cappello, ``Bifurcation in the MHD behaviour of a self-organizing system: the RFP,'' Plasma Phys. Control. Fusion 46, B313 (2004) [3] D. Bonfiglio, S. Cappello, D.F. Escande, ``Dominant electrostatic nature of the Reversed Field Pinch dynamo,'' Phys. Rev. Lett. 94, 145001 (2005) In collaboration with D.F. Escande and D. Bonfiglio.

  17. A Wheel Electrometer to Measure Electrostatic Fields on the Martian Surface

    NASA Technical Reports Server (NTRS)

    Calle, C. I.; Buhler, C. R.; Mantovani, J. G.; Groop, E. E.; Buehler, M. G.; Nowicki, A. W.

    2003-01-01

    A system of embedded sensors that can be incorporated into the wheel of any future mission rover would provide for a simple and fairly unobtrusive way to measure the distribution of electrostatic fields on the Martian surface and to measure variations in soil electrostatic response. This technology could perhaps be applied to different types of sensors that require the mobility provided by a rover s wheel.

  18. Numerical Investigation of Two-Phase Flows With Charged Droplets in Electrostatic Field

    NASA Technical Reports Server (NTRS)

    Kim, Sang-Wook

    1996-01-01

    A numerical method to solve two-phase turbulent flows with charged droplets in an electrostatic field is presented. The ensemble-averaged Navier-Stokes equations and the electrostatic potential equation are solved using a finite volume method. The transitional turbulence field is described using multiple-time-scale turbulence equations. The equations of motion of droplets are solved using a Lagrangian particle tracking scheme, and the inter-phase momentum exchange is described by the Particle-In-Cell scheme. The electrostatic force caused by an applied electrical potential is calculated using the electrostatic field obtained by solving a Laplacian equation and the force exerted by charged droplets is calculated using the Coulombic force equation. The method is applied to solve electro-hydrodynamic sprays. The calculated droplet velocity distributions for droplet dispersions occurring in a stagnant surrounding are in good agreement with the measured data. For droplet dispersions occurring in a two-phase flow, the droplet trajectories are influenced by aerodynamic forces, the Coulombic force, and the applied electrostatic potential field.

  19. Long period preservation of marine products using electrostatic field

    NASA Astrophysics Data System (ADS)

    Okumura, Takamasa; Yaegashi, Taro; Yamada, Kazuki; Ito, Takanori; Takahashi, Katsuyuki; Aisawa, Sumio; Takaki, Koichi; Yamazaki, Shigeyoshi; Syuto, Bunei

    2016-07-01

    The effect of an AC electric field on the freshness of marine products was experimentally investigated. An AC voltage of 10 kV with 50 Hz in frequency was generated with a transformer and applied to a plane electrode set in an incubator. The biological material was the gonad of purple sea urchin. The AC electric field with 50 Hz in frequency was applied to the gonad at -1 °C for 7 days. Freshness was evaluated by measuring protein release and lactate dehydrogenase (LDH) activity. The results showed that the protein release and LDH activity in the gonad were suppressed by applying the AC electric field, compared with that without the AC electric field. Moreover, the gonad was treated with the AC electric field at -5 °C for 3 days and then preserved at 0 °C for 1 day without the field. This electrical field treatment of the gonad prolonged the freshness date for more than 10 days under 4 °C preservation condition. In addition, the permeability of the cell membrane was suppressed by applying the AC electric field. Concerning the relationship between permeability and AC electric field, the conformational change of bovine serum albumin (BSA) induced by the AC electric field was evaluated on the basis of UV absorption spectra. The results revealed that the secondary and/or higher-order structure gradually changes with preservation period. The conformational change of the BSA molecule was induced by applying the AC electric field.

  20. Dual field effects in spinel ferrite field effect devices: electrostatic carrier doping and redox reactions

    NASA Astrophysics Data System (ADS)

    Tanaka, Hidekazu

    2015-03-01

    Spinel ferrite is a good candidate as a tunable magnetic semiconductor with high TC. Here, we report the gate-induced conductance modulation of (Fe3-xZnx) O4 solid solution to demonstrate the dual contributions of volatile and non-volatile field effects arising from electronic carrier doping and redox reactions using field effect device structure with a ferroelectric Pb(Zr,Ti)O3 and an ionic liquid DEME-TFSI. In the Pb(Zr,Ti)O3/(Fe2.5Zn0.5) O4 FET, the gate voltage dependence of channel conductance on the (Fe,Zn)3O4 layer shows the typical hysteresis behavior reflecting the ferroelectric polarization, indicating the static carrier modulation . In contrast, in the DEME-TFSI/(Fe2.5Zn0.5) O4 FET, a large hysteresis observed in the drain current vs gate voltage characteristics is not accounted for solely by electrostatic doping, strongly suggesting the presence of chemical reactions. In more details, the characteristic hysteresis virtually disappears for the heavily Zn substituted system,(Fe2.2Zn0.8) O4 with less carrier concentration. These observations revealed the coexistence of two types of field effects in the Fe3-xZnxO4 devices, and the tuning of field-effect characteristics via composition engineering should be extremely useful for fabricating high-performance oxide field-effect devices.

  1. Computational modeling of electrostatic charge and fields produced by hypervelocity impact

    SciTech Connect

    Crawford, David A.

    2015-05-19

    Following prior experimental evidence of electrostatic charge separation, electric and magnetic fields produced by hypervelocity impact, we have developed a model of electrostatic charge separation based on plasma sheath theory and implemented it into the CTH shock physics code. Preliminary assessment of the model shows good qualitative and quantitative agreement between the model and prior experiments at least in the hypervelocity regime for the porous carbonate material tested. The model agrees with the scaling analysis of experimental data performed in the prior work, suggesting that electric charge separation and the resulting electric and magnetic fields can be a substantial effect at larger scales, higher impact velocities, or both.

  2. New physics and chemistry in high electrostatic fields

    NASA Astrophysics Data System (ADS)

    Karahka, M. L.; Kreuzer, H. J.

    2016-01-01

    Fields of the order of volts per meter exist along micron-sized tips. They are of the magnitude of fields inside atoms and molecules and can affect their electronic structure. This leads to a continuous periodic table resulting in new field-induced chemistry. We will present a tutorial treatment of this new physics and chemistry explaining such surprising phenomena like covalent bonding of helium to metal surfaces, metallization of semiconductors and insulators, and more.

  3. Fast and precise computation of electrostatic fields with a charge simulation method using modern programming techniques

    SciTech Connect

    Schmidt, S.; Zech, G.; Otto, W.

    1996-05-01

    A precise computation of the electrostatic field is of considerable importance for the optimization of devices with electrooptical imaging. Another field of interest is the development of particle detectors like wire chambers or microstrip chambers. Inside a gas volume of such a detector a high electrostatic field is produced at small electrodes. Particles passing the detector ionize a certain number of gas molecules. The electrons produced by this process are moving along the field lines. When they reach a high field region they are accelerated and in turn ionize the gas. This leads to a charge avalanche that induces a signal on the electrodes that can be measured. To simulate these detectors the field has to be computed to high precision, especially in regions where the field is large, since the gas gain depends exponentially on the field strength. For signal simulation also the drift velocity of the positive ions which is proportional to the field, the induced charges on the electrodes, and the capacitances are of interest. Here a method to reduce the computational effort for numerical calculation of electrostatic fields by a Charge Simulation Method is introduced. By simplifying complex charge configurations for the evaluation of the field at large distances, the computation time can be reduced considerably preserving high precision. Since the method is ideally suited to object-oriented programming it has been implemented in C++.

  4. Impulse Magnetic Fields Generated by Electrostatic Discharges in Protoplanetary Nebulae

    NASA Technical Reports Server (NTRS)

    Tunyi, I.; Guba, P.; Roth, L. E.; Timko, M.

    2002-01-01

    We examine quantitative aspects associated with the hypothesis of nebular lightnings as a source of impulse magnetic fields. Our findings support our previous accretion model in which a presence of impulse magnetic fields was of a key necessity. Additional information is contained in the original extended abstract.

  5. Mapping the electrostatic force field of single molecules from high-resolution scanning probe images

    PubMed Central

    Hapala, Prokop; Švec, Martin; Stetsovych, Oleksandr; van der Heijden, Nadine J.; Ondráček, Martin; van der Lit, Joost; Mutombo, Pingo; Swart, Ingmar; Jelínek, Pavel

    2016-01-01

    How electronic charge is distributed over a molecule determines to a large extent its chemical properties. Here, we demonstrate how the electrostatic force field, originating from the inhomogeneous charge distribution in a molecule, can be measured with submolecular resolution. We exploit the fact that distortions typically observed in high-resolution atomic force microscopy images are for a significant part caused by the electrostatic force acting between charges of the tip and the molecule of interest. By finding a geometrical transformation between two high-resolution AFM images acquired with two different tips, the electrostatic force field or potential over individual molecules and self-assemblies thereof can be reconstructed with submolecular resolution. PMID:27230940

  6. Nonresonant Charged-Particle Acceleration by Electrostatic Waves Propagating across Fluctuating Magnetic Field

    NASA Astrophysics Data System (ADS)

    Artemyev, A. V.; Neishtadt, A. I.; Vasiliev, A. A.; Zelenyi, L. M.

    2015-10-01

    In this Letter, we demonstrate the effect of nonresonant charged-particle acceleration by an electrostatic wave propagating across the background magnetic field. We show that in the absence of resonance (i.e., when particle velocities are much smaller than the wave phase velocity) particles can be accelerated by electrostatic waves provided that the adiabaticity of particle motion is destroyed by magnetic field fluctuations. Thus, in a system with stochastic particle dynamics the electrostatic wave should be damped even in the absence of Landau resonance. The proposed mechanism is responsible for the acceleration of particles that cannot be accelerated via resonant wave-particle interactions. Simplicity of this straightforward acceleration scenario indicates a wide range of possible applications.

  7. Electrostatic field-exposed water in nanotube at constant axial pressure

    PubMed Central

    He, Yuchi; Sun, Gang; Koga, Kenichiro; Xu, Limei

    2014-01-01

    Water confined within nanoscale geometries under external field has many interesting properties which is very important for its application in biological processes and engineering. Using molecular dynamics simulations, we investigate the effect of external fields on polarization and structure as well as phase transformations of water confined within carbon nanotubes. We find that dipoles of water molecules tend to align along external field in nanoscale cylindrical confinement. Such alignment directly leads to the longitudinal electrostriction and cross-sectional dilation of water in nanotube. It also influences the stability of ice structures. As the electrostatic field strengthens, the confined water undergoes phase transitions from a prism structure to a helical one to a single chain as the electrostatic field strengthens. These results imply a rich phase diagram of the confined water due to the presence of external electriostatic field, which can be of importance for the industrial applications in nanopores. PMID:25318649

  8. Simulation of electrostatic ion instabilities in the presence of parallel currents and transverse electric fields

    NASA Technical Reports Server (NTRS)

    Nishikawa, K.-I.; Ganguli, G.; Lee, Y. C.; Palmadesso, P. J.

    1989-01-01

    A spatially two-dimensional electrostatic PIC simulation code was used to study the stability of a plasma equilibrium characterized by a localized transverse dc electric field and a field-aligned drift for L is much less than Lx, where Lx is the simulation length in the x direction and L is the scale length associated with the dc electric field. It is found that the dc electric field and the field-aligned current can together play a synergistic role to enable the excitation of electrostatic waves even when the threshold values of the field aligned drift and the E x B drift are individually subcritical. The simulation results show that the growing ion waves are associated with small vortices in the linear stage, which evolve to the nonlinear stage dominated by larger vortices with lower frequencies.

  9. Electrostatic fields in hybrid heterojunctions: Field-effect transistor, topological insulator, & thermoelectronic application

    NASA Astrophysics Data System (ADS)

    Ireland, Robert Matthew

    Organic semiconductors (OSC) are still surging in popularity for sustainable electronic devices, especially since they can perform as well as amorphous and polycrystalline silicon materials. Although OSCs have processing advantages that give rise to novel opportunities compared to inorganic semiconductors (ISCs), devices usually require inorganic materials for highly conductive connections or other functionality. Significantly, OSCs can be used to tune or modify the behavior of inorganic semiconductors (ISCs) by exploiting the junction between two semiconductors (a heterojunction). The possible creation of stable interfaces between ISCs and OSCs provides a practically limitless range of functionalities. Broadly, my goal is to study interfaces between OSCs and ISCs (hybrid heterojunctions) by testing devices of different configurations and altering the internal fields systematically, as well as with the aid of electron- and force-microscopy, and photoelectron spectroscopy. This thesis contains three major sections based around nascent, relevant applications: field-effect transistors, topological insulators, and thermoelectrics. First I study the effects of combining tellurium thin-films with OSC layers in field-effect transistors, where the organic acts both as a substrate modification layer and electrostatic gate. Secondly, I use electron withdrawing OSCs as gating materials for modifying Bi2Se3 in order to realize fundamental topological insulator behavior. Thirdly, I develop polymer-particle composites, including doping of the polymers and stabilization of inorganic particles with an electronic density of states that supports good thermoelectric behavior. We show that OSCs can undeniably be used to significantly modify properties of ISCs, namely tellurium, bismuth selenide, and organometallic compounds. I will first discuss the interfacial fields intrinsic to each heterojunction or device structure. Then I implement an additional electrostatic gate as part of the

  10. Effects of cycle duration of an external electrostatic field on anammox biomass activity

    PubMed Central

    Yin, Xin; Qiao, Sen; Zhou, Jiti

    2016-01-01

    In this study, the effects of different cycle durations of an external electrostatic field on an anammox biomass were investigated. The total application time per day was 12 h at 2 V/cm for different cycle durations (i.e., continuous application-resting time) of 3 h-3 h, 6 h-6 h, and 12 h-12 h. Compared with the control reactor, the nitrogen removal rates (NRRs) increased by 18.7%, 27.4% and 8.50% using an external electrostatic field application with a continuous application time of 3 h, 6 h and 12 h. Moreover, after the reactor was running smoothly for approximately 215 days under the optimal electrostatic field condition (mode 2, continuous application-rest time: 6 h-6 h), the total nitrogen (TN) removal rate reached a peak value of approximately 6468 g-N/m3/d, which was 44.7% higher than the control. The increase in 16S rRNA gene copy numbers, heme c content and enzyme activities were demonstrated to be the main reasons for enhancement of the NRR of the anammox process. Additionally, transmission electron microscope observations proved that a morphological change in the anammox biomass occurred under an electrostatic field application. PMID:26794647

  11. Control of Flowing Liquid Films by Electrostatic Fields in Space

    NASA Technical Reports Server (NTRS)

    Griffing, E. M.; Bankoff, S. G.; Schluter, R. A.; Miksis, M. J.

    1999-01-01

    The interaction of a spacially varying electric field and a flowing thin liquid film is investigated experimentally for the design of a proposed light weight space radiator. Electrodes are utilized to create a negative pressure at the bottom of a fluid film and suppress leaks if a micrometeorite punctures the radiator surface. Experimental pressure profiles under a vertical falling film, which passes under a finite electrode, show that fields of sufficient strength can be used safely in such a device. Leak stopping experiments demonstrate that leaks can be stopped with an electric field in earth gravity. A new type of electrohydrodynamic instability causes waves in the fluid film to develop into 3D cones and touch the electrode at a critical voltage. Methods previously used to calculate critical voltages for non moving films are shown to be inappropriate for this situation. The instability determines a maximum field which may be utilized in design, so the possible dependence of critical voltage on electrode length, height above the film, and fluid Reynolds number is discussed.

  12. A wide bandwidth electrostatic field sensor for lightning research

    NASA Technical Reports Server (NTRS)

    Zaepfel, K. P.

    1986-01-01

    Data obtained from UHF Radar observation of direct-lightning strikes to the NASA F-106B airplane have indicated that most of the 690 strikes acquired during direct-strike lightning tests were triggered by the aircraft. As an aid in understanding the triggered lightning process, a wide bandwidth electric field measuring system was designed for the F-106B by implementing a clamped-detection signal processing concept originated at the Air Force Cambridge Research Lab in 1953. The detection scheme combines the signals from complementary stator pairs clamped to zero volts at the exact moment when each stator pair is maximally shielded by the rotor, a process that restores the dc level lost by the charge amplifier. The new system was implemented with four shutter-type field mills located at strategic points on the airplane. The bandwidth of the new system was determined in the laboratory to be from dc to over 100 Hz, whereas past designs had upper limits of 10 Hz to 100 Hz. To obtain the undisturbed electric field vector and total aircraft charge, the airborne field mill system is calibrated by using techniques involving results from ground and flight calibrations of the F-106B, laboratory tests of a metallized model, and a finite-difference time-domain electromagnetic computer code.

  13. A wide bandwidth electrostatic field sensor for lightning research

    NASA Technical Reports Server (NTRS)

    Zaepfel, Klaus P.

    1989-01-01

    Data obtained from UHF radar observation of direct-lightning strikes to the NASA F-106B aircraft have indicated that most of the 690 strikes acquired during direct-strike lightning tests were triggered by the aircraft. As an aid in understanding the triggered lightning process, a wide bandwidth electric field measuring system was designed for the F-106B by implementing a clamped-detection signal processing concept originated at the Air Force Cambridge Research Lab in 1953. The detection scheme combines the signals from complementary stator pairs clamped to zero bolts at the exact moment when each stator pair is maximally shielded by the rotor, a process that restores the dc level lost by the charge amplifier. The system was implemented with four shutter-type field mills located at strategic points on the aircraft. The bandwidth of the system was determined in the laboratory to be from dc to over 100 Hz, whereas past designs had upper limits of 10 to 100 Hz. To obtain the undisturbed electric field vector and total aircraft charge, the airborne field mill system is calibrated by using techniques involving results from ground and flight calibrations of the F-106B, laboratory tests of a metallized model, and a finite difference time-domain electromagnetic computer code.

  14. Determination of the electrostatic lever arm of carbon nanotube field effect transistors using Kelvin force microscopy

    NASA Astrophysics Data System (ADS)

    Brunel, David; Deresmes, Dominique; Mélin, Thierry

    2009-06-01

    We use Kelvin force microscopy (KFM) to study the electrostatic properties of single-walled carbon nanotube field effect transistor devices (CNTFETs) with backgate geometry at room temperature. We show that KFM maps recorded as a function of the device backgate polarization enable a complete phenomenological determination of the averaging effects associated with the KFM probe side capacitances, and thus, to obtain KFM measurements with quantitative character. The value of the electrostatic lever arm of the CNTFET is determined from KFM measurements and found in agreement with transport measurements based on Coulomb blockade.

  15. Modeling and Electrostatic Focusing for a Field Emission Electron Source

    DTIC Science & Technology

    2013-06-01

    mechanisms of the beam formation, transport, field emission energy distributions, the effects of the emission properties, and parametric studies are...metals, the valence electrons possess the conduction energy band and are described by Sommerfeld free electron gas model with Fermi- Dirac statistics...which defines the electrons energy distribution. For the emission from not electrical conductors the Sommerfeld theory of metals with Fermi- Dirac

  16. Electrostatics 1979,

    DTIC Science & Technology

    1979-11-28

    UK also perform consulting work on elec- trostatic problems. Two of these are the Wolfson Electrostatics Unit of the Department of Electrical...Cross (Wolfson Electrostatics Advisory Unit , Univ. of Southampton, UK ) reported that the application of high electro- static fields does indeed aid heat...062 917 OFFICE OF NAVAL RESEARCH LONDON ( ENGLAND ) F/0 20/3 ELECTROSTATICS 1979. (U) NOV 79 1 KAUFMAN UNCLASSIFIE’ ONLC-1 7 N JJ32 L136 I L. - ’III

  17. General Model for Treating Short-Range Electrostatic Penetration in a Molecular Mechanics Force Field.

    PubMed

    Wang, Qiantao; Rackers, Joshua A; He, Chenfeng; Qi, Rui; Narth, Christophe; Lagardere, Louis; Gresh, Nohad; Ponder, Jay W; Piquemal, Jean-Philip; Ren, Pengyu

    2015-06-09

    Classical molecular mechanics force fields typically model interatomic electrostatic interactions with point charges or multipole expansions, which can fail for atoms in close contact due to the lack of a description of penetration effects between their electron clouds. These short-range penetration effects can be significant and are essential for accurate modeling of intermolecular interactions. In this work we report parametrization of an empirical charge-charge function previously reported (Piquemal J.-P.; J. Phys. Chem. A2003, 107, 10353) to correct for the missing penetration term in standard molecular mechanics force fields. For this purpose, we have developed a database (S101×7) of 101 unique molecular dimers, each at 7 different intermolecular distances. Electrostatic, induction/polarization, repulsion, and dispersion energies, as well as the total interaction energy for each complex in the database are calculated using the SAPT2+ method (Parker T. M.; J. Chem. Phys.2014, 140, 094106). This empirical penetration model significantly improves agreement between point multipole and quantum mechanical electrostatic energies across the set of dimers and distances, while using only a limited set of parameters for each chemical element. Given the simplicity and effectiveness of the model, we expect the electrostatic penetration correction will become a standard component of future molecular mechanics force fields.

  18. Electromagnetic field generation in the downstream of electrostatic shocks due to electron trapping.

    PubMed

    Stockem, A; Grismayer, T; Fonseca, R A; Silva, L O

    2014-09-05

    A new magnetic field generation mechanism in electrostatic shocks is found, which can produce fields with magnetic energy density as high as 0.01 of the kinetic energy density of the flows on time scales ∼10(4)ωpe-1. Electron trapping during the shock formation process creates a strong temperature anisotropy in the distribution function, giving rise to the pure Weibel instability. The generated magnetic field is well confined to the downstream region of the electrostatic shock. The shock formation process is not modified, and the features of the shock front responsible for ion acceleration, which are currently probed in laser-plasma laboratory experiments, are maintained. However, such a strong magnetic field determines the particle trajectories downstream and has the potential to modify the signatures of the collisionless shock.

  19. Maximum Langmuir Fields in Planetary Foreshocks Determined from the Electrostatic Decay Threshold

    NASA Technical Reports Server (NTRS)

    Robinson, P. A.; Cairns, Iver H.

    1995-01-01

    Maximum electric fields of Langmuir waves at planetary foreshocks are estimated from the threshold for electrostatic decay, assuming it saturates beam driven growth, and incorporating heliospheric variation of plasma density and temperature. Comparisons with spacecraft observations yields good quantitative agreement. Observations in type 3 radio sources are also in accord with this interpretation. A single mechanism can thus account for the highest fields of beam driven waves in both contexts.

  20. Electrostatic-field-enhanced photoexfoliation of bilayer benzene: A first-principles study

    NASA Astrophysics Data System (ADS)

    Uchida, Kazuki; Silaeva, Elena P.; Watanabe, Kazuyuki

    2016-06-01

    Photoexfoliation of bilayer benzene in an external electrostatic (dc) field is studied using time-dependent density functional theory combined with molecular dynamics. We find that the dc-field-induced force on the upper benzene in addition to the repulsive interaction between the positively charged benzene molecules induced by the laser field leads to fast athermal exfoliation. Thus, we conclude that the dc field enhances the photoexfoliation due to dc-field emission in addition to laser-assisted photoemission. The athermal exfoliation process is shown to depend crucially on the charge state of benzene molecules rather than on the excitation energy supplied by the laser.

  1. Determining polarizable force fields with electrostatic potentials from quantum mechanical linear response theory

    NASA Astrophysics Data System (ADS)

    Wang, Hao; Yang, Weitao

    2016-06-01

    We developed a new method to calculate the atomic polarizabilities by fitting to the electrostatic potentials (ESPs) obtained from quantum mechanical (QM) calculations within the linear response theory. This parallels the conventional approach of fitting atomic charges based on electrostatic potentials from the electron density. Our ESP fitting is combined with the induced dipole model under the perturbation of uniform external electric fields of all orientations. QM calculations for the linear response to the external electric fields are used as input, fully consistent with the induced dipole model, which itself is a linear response model. The orientation of the uniform external electric fields is integrated in all directions. The integration of orientation and QM linear response calculations together makes the fitting results independent of the orientations and magnitudes of the uniform external electric fields applied. Another advantage of our method is that QM calculation is only needed once, in contrast to the conventional approach, where many QM calculations are needed for many different applied electric fields. The molecular polarizabilities obtained from our method show comparable accuracy with those from fitting directly to the experimental or theoretical molecular polarizabilities. Since ESP is directly fitted, atomic polarizabilities obtained from our method are expected to reproduce the electrostatic interactions better. Our method was used to calculate both transferable atomic polarizabilities for polarizable molecular mechanics' force fields and nontransferable molecule-specific atomic polarizabilities.

  2. Determining polarizable force fields with electrostatic potentials from quantum mechanical linear response theory

    PubMed Central

    Yang, Weitao

    2016-01-01

    We developed a new method to calculate the atomic polarizabilities by fitting to the electrostatic potentials (ESPs) obtained from quantum mechanical (QM) calculations within the linear response theory. This parallels the conventional approach of fitting atomic charges based on electrostatic potentials from the electron density. Our ESP fitting is combined with the induced dipole model under the perturbation of uniform external electric fields of all orientations. QM calculations for the linear response to the external electric fields are used as input, fully consistent with the induced dipole model, which itself is a linear response model. The orientation of the uniform external electric fields is integrated in all directions. The integration of orientation and QM linear response calculations together makes the fitting results independent of the orientations and magnitudes of the uniform external electric fields applied. Another advantage of our method is that QM calculation is only needed once, in contrast to the conventional approach, where many QM calculations are needed for many different applied electric fields. The molecular polarizabilities obtained from our method show comparable accuracy with those from fitting directly to the experimental or theoretical molecular polarizabilities. Since ESP is directly fitted, atomic polarizabilities obtained from our method are expected to reproduce the electrostatic interactions better. Our method was used to calculate both transferable atomic polarizabilities for polarizable molecular mechanics’ force fields and nontransferable molecule-specific atomic polarizabilities. PMID:27305996

  3. Determining polarizable force fields with electrostatic potentials from quantum mechanical linear response theory.

    PubMed

    Wang, Hao; Yang, Weitao

    2016-06-14

    We developed a new method to calculate the atomic polarizabilities by fitting to the electrostatic potentials (ESPs) obtained from quantum mechanical (QM) calculations within the linear response theory. This parallels the conventional approach of fitting atomic charges based on electrostatic potentials from the electron density. Our ESP fitting is combined with the induced dipole model under the perturbation of uniform external electric fields of all orientations. QM calculations for the linear response to the external electric fields are used as input, fully consistent with the induced dipole model, which itself is a linear response model. The orientation of the uniform external electric fields is integrated in all directions. The integration of orientation and QM linear response calculations together makes the fitting results independent of the orientations and magnitudes of the uniform external electric fields applied. Another advantage of our method is that QM calculation is only needed once, in contrast to the conventional approach, where many QM calculations are needed for many different applied electric fields. The molecular polarizabilities obtained from our method show comparable accuracy with those from fitting directly to the experimental or theoretical molecular polarizabilities. Since ESP is directly fitted, atomic polarizabilities obtained from our method are expected to reproduce the electrostatic interactions better. Our method was used to calculate both transferable atomic polarizabilities for polarizable molecular mechanics' force fields and nontransferable molecule-specific atomic polarizabilities.

  4. Effect of surface roughness on the electrostatic field of an RPC

    NASA Astrophysics Data System (ADS)

    Jash, A.; Majumdar, N.; Mukhopadhyay, S.; Chattopadhyay, S.

    2016-10-01

    The inner surfaces of the electrodes encompassing the gas volume of a Resistive Plate Chamber (RPC) have been found to exhibit asperities with three kind of feature grossly. The desired uniform electric field within the gas volume of RPC is expected to be affected due to presence of these asperities, which will eventually affect the final response from the detector. In this work, an attempt has been made to model the highly complex roughness of the electrode surfaces and compute its effect on the electrostatic field within RPC gas chamber. The different aspects of surface structures have been modeled and their effect on the electrostatic field has been calculated. The calculations have been performed numerically using Finite Element Method (FEM) and Boundary Element Method (BEM) and the two methods have been compared in this context.

  5. A SPICE Model and Electrostatic Field Analysis of the MOS Turn-Off Thyristor

    SciTech Connect

    Kelly, D Q; Mayhall, D J; Wilson, M J; Lahowe, D A

    2002-08-05

    This paper presents a circuit model and an electrostatic field analysis with an approximate model of the SDM170HK MOS turn-off thyristor (MTO) fabricated by Silicon Power Corporation. The circuit model consists of five cells, each containing two bipolar junction transistors and three resistors. The turn-off feature of the MTO was simulated by inserting an array of 21 Fairchild FDS6670A MOSFET importable sub-circuit components between the cathode and the turn-on gate. The model was then used to create a four-terminal sub-circuit component representing the MTO that can be readily imported into computer-aided circuit design programs such as PSPICE and Micro-Cap. The generated static I-V characteristics and simulated switching waveforms are shown. The electrostatic field analysis was done for the maximum operating voltage of 4.5 kV using the Ansoft Maxwell 3D field simulator. Electrostatic field magnitudes that exceed the nominal air breakdown threshold of 30 kV/cm were observed surrounding the simulated turn-off gate wire, the turn-off gate ring contact, and the cathode ring contact. The resulting areas of high fields are a concern, as arc track marks have been found on the inner surface of the ceramic insulator near the internal gate connections of a failed device.

  6. Deformation of doubly clamped single-walled carbon nanotubes in an electrostatic field.

    PubMed

    Wang, Zhao; Philippe, Laetitia

    2009-05-29

    In this Letter, we demonstrate a strong dependence of the electrostatic deformation of doubly clamped single-walled carbon nanotubes on both the field strength and the tube length, using molecular simulations. Metallic nanotubes are found to be more sensitive to an electric field than semiconducting ones of the same size. For a given electric field, the induced deformation increases with tube length but decreases with tube radius. Furthermore, it is found that nanotubes can be more efficiently bent in a center-oriented transverse electric field.

  7. Electrostatic ion instabilities in the presence of parallel currents and transverse electric fields

    NASA Technical Reports Server (NTRS)

    Ganguli, G.; Palmadesso, P. J.

    1988-01-01

    The electrostatic ion instabilities are studied for oblique propagation in the presence of magnetic field-aligned currents and transverse localized electric fields in a weakly collisional plasma. The presence of transverse electric fields result in mode excitation for magnetic field aligned current values that are otherwise stable. The electron collisions enhance the growth while ion collisions have a damping effect. These results are discussed in the context of observations of low frequency ion modes in the auroral ionosphere by radar and rocket experiments.

  8. Electrostatic ion instabilities in the presence of parallel currents and transverse electric fields

    NASA Technical Reports Server (NTRS)

    Ganguli, G.; Palmadesso, P. J.

    1988-01-01

    The electrostatic ion instabilities are studied for oblique propagation in the presence of magnetic field-aligned currents and transverse localized electric fields in a weakly collisional plasma. The presence of transverse electric fields result in mode excitation for magnetic field aligned current values that are otherwise stable. The electron collisions enhance the growth while ion collisions have a damping effect. These results are discussed in the context of observations of low frequency ion modes in the auroral ionosphere by radar and rocket experiments.

  9. [The in vitro influence of the external electrostatic field on the physical parameters of erythrocyte membranes].

    PubMed

    Artsruni, G G; Saakian, G V; Pogosian, G A

    2013-01-01

    The in vitro influence of external electrostatic fields with 200 kV/m tension on the biophysical parameters of the erythrocyte membranes and their ghosts of white outbred rats was studied. The investigation on the parameters of erythrocyte membranes and their ghosts, particularly, their microviscosity, the amount and degree of membrane proteins submersion in lipids, polarity in depth of the membrane bilayer and its viscositywas carried out by the spectrofluorimeteric method using pyrene as a hydrophobic fluorescent probe. The analyses of literature data, findings of the current study and their comparison with the results of our previous works allow of concluding that the in vitro influence of external electrostatic fields with 200 kV/m tension on the erythrocyte membranes and their ghosts occurs at different sites of membrane. It is shown that the preliminary exposure of erythrocytes in external electrostatic fields leads to the changes of the parameters both of a membrane surface layer and the intra-membrane domains. So, the decrease in the strength of peripheral proteins binding to the erythrocyte membranes and the increase in the micriviscosity of the lipid bilayer are observed. The influence of the field on the ghosts of intact erythrocytes results in alterations of the studied parameters only of the membrane surface.

  10. Fermi level pinning induced electrostatic fields and band bending at organic heterojunctions

    SciTech Connect

    Akaike, K.; Koch, N.; Oehzelt, M.

    2014-12-01

    The energy level alignment at interfaces between organic semiconductors is of direct relevance to understand charge carrier generation and recombination in organic electronic devices. Commonly, work function changes observed upon interface formation are interpreted as interface dipoles. In this study, using ultraviolet and X-ray photoelectron spectroscopy, complemented by electrostatic calculations, we find a huge work function decrease of up to 1.4 eV at the C{sub 60} (bottom layer)/zinc phthalocyanine (ZnPc, top layer) interface prepared on a molybdenum trioxide (MoO{sub 3}) substrate. However, detailed measurements of the energy level shifts and electrostatic calculations reveal that no interface dipole occurs. Instead, upon ZnPc deposition, a linear electrostatic potential gradient is generated across the C{sub 60} layer due to Fermi level pinning of ZnPc on the high work function C{sub 60}/MoO{sub 3} substrate, and associated band-bending within the ZnPc layer. This finding is generally of importance for understanding organic heterojunctions when Fermi level pinning is involved, as induced electrostatic fields alter the energy level alignment significantly.

  11. Computational modeling of electrostatic charge and fields produced by hypervelocity impact

    DOE PAGES

    Crawford, David A.

    2015-05-19

    Following prior experimental evidence of electrostatic charge separation, electric and magnetic fields produced by hypervelocity impact, we have developed a model of electrostatic charge separation based on plasma sheath theory and implemented it into the CTH shock physics code. Preliminary assessment of the model shows good qualitative and quantitative agreement between the model and prior experiments at least in the hypervelocity regime for the porous carbonate material tested. The model agrees with the scaling analysis of experimental data performed in the prior work, suggesting that electric charge separation and the resulting electric and magnetic fields can be a substantial effectmore » at larger scales, higher impact velocities, or both.« less

  12. Formation of a field reversed configuration for magnetic and electrostatic confinement of plasma

    SciTech Connect

    Rostoker, Norman; Binderbauer, Michl; Qerushi, Artan; Tahsiri, Hooshang

    2006-02-07

    A system and method for containing plasma and forming a Field Reversed Configuration (FRC) magnetic topology are described in which plasma ions are contained magnetically in stable, non-adiabatic orbits in the FRC. Further, the electrons are contained electrostatically in a deep energy well, created by tuning an externally applied magnetic field. The simultaneous electrostatic confinement of electrons and magnetic confinement of ions avoids anomalous transport and facilitates classical containment of both electrons and ions. In this configuration, ions and electrons may have adequate density and temperature so that upon collisions they are fused together by nuclear force, thus releasing fusion energy. Moreover, the fusion fuel plasmas that can be used with the present confinement system and method are not limited to neutronic fuels only, but also advantageously include advanced fuels.

  13. Formation of a field reversed configuration for magnetic and electrostatic confinement of plasma

    DOEpatents

    Rostoker, Norman; Binderbauer, Michl; Qerushi, Artan; Tahsiri, Hooshang

    2007-02-20

    A system and method for containing plasma and forming a Field Reversed Configuration (FRC) magnetic topology are described in which plasma ions are contained magnetically in stable, non-adiabatic orbits in the FRC. Further, the electrons are contained electrostatically in a deep energy well, created by tuning an externally applied magnetic field. The simultaneous electrostatic confinement of electrons and magnetic confinement of ions avoids anomalous transport and facilitates classical containment of both electrons and ions. In this configuration, ions and electrons may have adequate density and temperature so that upon collisions they are fused together by nuclear force, thus releasing fusion energy. Moreover, the fusion fuel plasmas that can be used with the present confinement system and method are not limited to neutronic fuels only, but also advantageously include advanced fuels.

  14. Formation of a field reversed configuration for magnetic and electrostatic confinement of plasma

    DOEpatents

    Rostoker, Norman; Binderbauer, Michl

    2003-12-16

    A system and method for containing plasma and forming a Field Reversed Configuration (FRC) magnetic topology are described in which plasma ions are contained magnetically in stable, non-adiabatic orbits in the FRC. Further, the electrons are contained electrostatically in a deep energy well, created by tuning an externally applied magnetic field. The simultaneous electrostatic confinement of electrons and magnetic confinement of ions avoids anomalous transport and facilitates classical containment of both electrons and ions. In this configuration, ions and electrons may have adequate density and temperature so that upon collisions they are fused together by nuclear force, thus releasing fusion energy. Moreover, the fusion fuel plasmas that can be used with the present confinement system and method are not limited to neutronic fuels only, but also advantageously include advanced fuels.

  15. Proximity Eliashberg theory of electrostatic field-effect doping in superconducting films

    NASA Astrophysics Data System (ADS)

    Ummarino, G. A.; Piatti, E.; Daghero, D.; Gonnelli, R. S.; Sklyadneva, Irina Yu.; Chulkov, E. V.; Heid, R.

    2017-08-01

    We calculate the effect of a static electric field on the critical temperature of a s -wave one band superconductor in the framework of proximity effect Eliashberg theory. In the weak electrostatic field limit the theory has no free parameters while, in general, the only free parameter is the thickness of the surface layer where the electric field acts. We conclude that the best situation for increasing the critical temperature is to have a very thin film of a superconducting material with a strong increase of electron-phonon (boson) constant upon charging.

  16. Methodology and application of high performance electrostatic field simulation in the KATRIN experiment

    NASA Astrophysics Data System (ADS)

    Corona, Thomas

    The Karlsruhe Tritium Neutrino (KATRIN) experiment is a tritium beta decay experiment designed to make a direct, model independent measurement of the electron neutrino mass. The experimental apparatus employs strong ( O[T]) magnetostatic and (O[10 5 V/m]) electrostatic fields in regions of ultra high (O[10-11 mbar]) vacuum in order to obtain precise measurements of the electron energy spectrum near the endpoint of tritium beta-decay. The electrostatic fields in KATRIN are formed by multiscale electrode geometries, necessitating the development of high performance field simulation software. To this end, we present a Boundary Element Method (BEM) with analytic boundary integral terms in conjunction with the Robin Hood linear algebraic solver, a nonstationary successive subspace correction (SSC) method. We describe an implementation of these techniques for high performance computing environments in the software KEMField, along with the geometry modeling and discretization software KGeoBag. We detail the application of KEMField and KGeoBag to KATRIN's spectrometer and detector sections, and demonstrate its use in furthering several of KATRIN's scientific goals. Finally, we present the results of a measurement designed to probe the electrostatic profile of KATRIN's main spectrometer in comparison to simulated results.

  17. Direct measurement of electrostatic fields using single Teflon nanoparticle attached to AFM tip

    PubMed Central

    2013-01-01

    Abstract A single 210-nm Teflon nanoparticle (sTNP) was attached to the vertex of a silicon nitride (Si3N4) atomic force microscope tip and charged via contact electrification. The charged sTNP can then be considered a point charge and used to measure the electrostatic field adjacent to a parallel plate condenser using 30-nm gold/20-nm titanium as electrodes. This technique can provide a measurement resolution of 250/100 nm along the X- and Z-axes, and the minimum electrostatic force can be measured within 50 pN. PACS 07.79.Lh, 81.16.-c, 84.37. + q PMID:24314111

  18. An optimized intermolecular force field for hydrogen-bonded organic molecular crystals using atomic multipole electrostatics.

    PubMed

    Pyzer-Knapp, Edward O; Thompson, Hugh P G; Day, Graeme M

    2016-08-01

    We present a re-parameterization of a popular intermolecular force field for describing intermolecular interactions in the organic solid state. Specifically we optimize the performance of the exp-6 force field when used in conjunction with atomic multipole electrostatics. We also parameterize force fields that are optimized for use with multipoles derived from polarized molecular electron densities, to account for induction effects in molecular crystals. Parameterization is performed against a set of 186 experimentally determined, low-temperature crystal structures and 53 measured sublimation enthalpies of hydrogen-bonding organic molecules. The resulting force fields are tested on a validation set of 129 crystal structures and show improved reproduction of the structures and lattice energies of a range of organic molecular crystals compared with the original force field with atomic partial charge electrostatics. Unit-cell dimensions of the validation set are typically reproduced to within 3% with the re-parameterized force fields. Lattice energies, which were all included during parameterization, are systematically underestimated when compared with measured sublimation enthalpies, with mean absolute errors of between 7.4 and 9.0%.

  19. An optimized intermolecular force field for hydrogen-bonded organic molecular crystals using atomic multipole electrostatics

    PubMed Central

    Pyzer-Knapp, Edward O.; Thompson, Hugh P. G.; Day, Graeme M.

    2016-01-01

    We present a re-parameterization of a popular intermolecular force field for describing intermolecular interactions in the organic solid state. Specifically we optimize the performance of the exp-6 force field when used in conjunction with atomic multipole electrostatics. We also parameterize force fields that are optimized for use with multipoles derived from polarized molecular electron densities, to account for induction effects in molecular crystals. Parameterization is performed against a set of 186 experimentally determined, low-temperature crystal structures and 53 measured sublimation enthalpies of hydrogen-bonding organic molecules. The resulting force fields are tested on a validation set of 129 crystal structures and show improved reproduction of the structures and lattice energies of a range of organic molecular crystals compared with the original force field with atomic partial charge electrostatics. Unit-cell dimensions of the validation set are typically reproduced to within 3% with the re-parameterized force fields. Lattice energies, which were all included during parameterization, are systematically underestimated when compared with measured sublimation enthalpies, with mean absolute errors of between 7.4 and 9.0%. PMID:27484370

  20. Drop-on-demand printing of conductive ink by electrostatic field induced inkjet head

    NASA Astrophysics Data System (ADS)

    Choi, Jaeyong; Kim, Yong-Jae; Lee, Sukhan; Son, Sang Uk; Ko, Han Seo; Nguyen, Vu Dat; Byun, Doyoung

    2008-11-01

    Recently, inkjet printing technology has become crucial in many industrial fabrication fields mainly due to its advantages of noncontact and fast pattern generation. In this paper, we investigate an electrostatic field induced inkjet printing system, which is based on an electrohydrodynamic process, for drop-on-demand jetting. In order to locate the optimal jetting conditions, we tested jetting performance for various bias voltages and pulse signals. To investigate the characteristics of drop-on-demand operation and micropatterning, we used conductive silver ink and examined the drops and lines patterned on a substrate.

  1. Electrostatic focal spot correction for x-ray tubes operating in strong magnetic fields.

    PubMed

    Lillaney, Prasheel; Shin, Mihye; Hinshaw, Waldo; Fahrig, Rebecca

    2014-11-01

    orthogonal field does not affect the electrostatic correction technique. However, rotation of the x-ray tube by 30° toward the MR bore increases the parallel magnetic field magnitude (∼72 mT). The presence of this larger parallel field along with the orthogonal field leads to incomplete correction. Monte Carlo simulations demonstrate that the mean energy of the x-ray spectrum is not noticeably affected by the electrostatic correction, but the output flux is reduced by 7.5%. The maximum orthogonal magnetic field magnitude that can be compensated for using the proposed design is 65 mT. Larger orthogonal field magnitudes cannot be completely compensated for because a pure electrostatic approach is limited by the dielectric strength of the vacuum inside the x-ray tube insert. The electrostatic approach also suffers from limitations when there are strong magnetic fields in both the orthogonal and parallel directions because the electrons prefer to stay aligned with the parallel magnetic field. These challenging field conditions can be addressed by using a hybrid correction approach that utilizes both active shielding coils and biasing electrodes.

  2. Electrostatic focal spot correction for x-ray tubes operating in strong magnetic fields

    PubMed Central

    Lillaney, Prasheel; Shin, Mihye; Hinshaw, Waldo; Fahrig, Rebecca

    2014-01-01

    field in addition to the orthogonal field does not affect the electrostatic correction technique. However, rotation of the x-ray tube by 30° toward the MR bore increases the parallel magnetic field magnitude (∼72 mT). The presence of this larger parallel field along with the orthogonal field leads to incomplete correction. Monte Carlo simulations demonstrate that the mean energy of the x-ray spectrum is not noticeably affected by the electrostatic correction, but the output flux is reduced by 7.5%. Conclusions: The maximum orthogonal magnetic field magnitude that can be compensated for using the proposed design is 65 mT. Larger orthogonal field magnitudes cannot be completely compensated for because a pure electrostatic approach is limited by the dielectric strength of the vacuum inside the x-ray tube insert. The electrostatic approach also suffers from limitations when there are strong magnetic fields in both the orthogonal and parallel directions because the electrons prefer to stay aligned with the parallel magnetic field. These challenging field conditions can be addressed by using a hybrid correction approach that utilizes both active shielding coils and biasing electrodes. PMID:25370658

  3. Green Ocean Amazon 2014/15 High-Volume Filter Sampling: Atmospheric Particulate Matter of an Amazon Tropical City and its Relationship to Population Health Field Campaign Report

    SciTech Connect

    Machado, C. M.; Santos, Erickson O.; Fernandes, Karenn S.; Neto, J. L.; Souza, Rodrigo A.

    2016-08-01

    Manaus, the capital of the Brazilian state of Amazonas, is developing very rapidly. Its pollution plume contains aerosols from fossil fuel combustion mainly due to vehicular emission, industrial activity, and a thermal power plant. Soil resuspension is probably a secondary source of atmospheric particles. The plume transports from Manaus to the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Climate Research Facility ARM site at Manacapuru urban pollutants as well as pollutants from pottery factories along the route of the plume. Considering the effects of particulate matter on health, atmospheric particulate matter was evaluated at this site as part of the ARM Facility’s Green Ocean Amazon 2014/15 (GoAmazon 2014/15) field campaign. Aerosol or particulate matter (PM) is typically defined by size, with the smaller particles having more health impact. Total suspended particulate (TSP) are particles smaller than 100 μm; particles smaller than 2.5 μm are called PM2.5. In this work, the PM2.5 levels were obtained from March to December of 2015, totaling 34 samples and TSP levels from October to December of 2015, totaling 17 samples. Sampling was conducted with PM2.5 and TSP high-volume samplers using quartz filters (Figure 1). Filters were stored during 24 hours in a room with temperature (21,1ºC) and humidity (44,3 %) control, in order to do gravimetric analyses by weighing before and after sampling. This procedure followed the recommendations of the Brazilian Association for Technical Standards local norm (NBR 9547:1997). Mass concentrations of particulate matter were obtained from the ratio between the weighted sample and the volume of air collected. Defining a relationship between particulate matter (PM2.5 and TSP) and respiratory diseases of the local population is an important goal of this project, since no information exists on that topic.

  4. Self-consistent field model for strong electrostatic correlations and inhomogeneous dielectric media

    SciTech Connect

    Ma, Manman Xu, Zhenli

    2014-12-28

    Electrostatic correlations and variable permittivity of electrolytes are essential for exploring many chemical and physical properties of interfaces in aqueous solutions. We propose a continuum electrostatic model for the treatment of these effects in the framework of the self-consistent field theory. The model incorporates a space- or field-dependent dielectric permittivity and an excluded ion-size effect for the correlation energy. This results in a self-energy modified Poisson-Nernst-Planck or Poisson-Boltzmann equation together with state equations for the self energy and the dielectric function. We show that the ionic size is of significant importance in predicting a finite self energy for an ion in an inhomogeneous medium. Asymptotic approximation is proposed for the solution of a generalized Debye-Hückel equation, which has been shown to capture the ionic correlation and dielectric self energy. Through simulating ionic distribution surrounding a macroion, the modified self-consistent field model is shown to agree with particle-based Monte Carlo simulations. Numerical results for symmetric and asymmetric electrolytes demonstrate that the model is able to predict the charge inversion at high correlation regime in the presence of multivalent interfacial ions which is beyond the mean-field theory and also show strong effect to double layer structure due to the space- or field-dependent dielectric permittivity.

  5. Self-consistent field model for strong electrostatic correlations and inhomogeneous dielectric media.

    PubMed

    Ma, Manman; Xu, Zhenli

    2014-12-28

    Electrostatic correlations and variable permittivity of electrolytes are essential for exploring many chemical and physical properties of interfaces in aqueous solutions. We propose a continuum electrostatic model for the treatment of these effects in the framework of the self-consistent field theory. The model incorporates a space- or field-dependent dielectric permittivity and an excluded ion-size effect for the correlation energy. This results in a self-energy modified Poisson-Nernst-Planck or Poisson-Boltzmann equation together with state equations for the self energy and the dielectric function. We show that the ionic size is of significant importance in predicting a finite self energy for an ion in an inhomogeneous medium. Asymptotic approximation is proposed for the solution of a generalized Debye-Hückel equation, which has been shown to capture the ionic correlation and dielectric self energy. Through simulating ionic distribution surrounding a macroion, the modified self-consistent field model is shown to agree with particle-based Monte Carlo simulations. Numerical results for symmetric and asymmetric electrolytes demonstrate that the model is able to predict the charge inversion at high correlation regime in the presence of multivalent interfacial ions which is beyond the mean-field theory and also show strong effect to double layer structure due to the space- or field-dependent dielectric permittivity.

  6. Self-consistent field model for strong electrostatic correlations and inhomogeneous dielectric media

    NASA Astrophysics Data System (ADS)

    Ma, Manman; Xu, Zhenli

    2014-12-01

    Electrostatic correlations and variable permittivity of electrolytes are essential for exploring many chemical and physical properties of interfaces in aqueous solutions. We propose a continuum electrostatic model for the treatment of these effects in the framework of the self-consistent field theory. The model incorporates a space- or field-dependent dielectric permittivity and an excluded ion-size effect for the correlation energy. This results in a self-energy modified Poisson-Nernst-Planck or Poisson-Boltzmann equation together with state equations for the self energy and the dielectric function. We show that the ionic size is of significant importance in predicting a finite self energy for an ion in an inhomogeneous medium. Asymptotic approximation is proposed for the solution of a generalized Debye-Hückel equation, which has been shown to capture the ionic correlation and dielectric self energy. Through simulating ionic distribution surrounding a macroion, the modified self-consistent field model is shown to agree with particle-based Monte Carlo simulations. Numerical results for symmetric and asymmetric electrolytes demonstrate that the model is able to predict the charge inversion at high correlation regime in the presence of multivalent interfacial ions which is beyond the mean-field theory and also show strong effect to double layer structure due to the space- or field-dependent dielectric permittivity.

  7. Force-field parametrization of retro-inverso modified residues: development of torsional and electrostatic parameters.

    PubMed

    Curcó, David; Rodríguez-Ropero, Francisco; Alemán, Carlos

    2006-01-01

    Torsional and the electrostatic parameters for molecular mechanics studies of retro-inverso modified peptides have been developed using quantum mechanical calculations. The resulting parameters have been compared with those calculated for conventional peptides. Rotational profiles, which were obtained spanning the corresponding dihedral angle, were corrected by removing the energy contributions associated to changes in interactions different from torsion under study. For this purpose, the torsional energy associated to each point of the profiles was estimated as the corresponding quantum mechanical energy minus the bonding and nonbonding energy contributions produced by the perturbations that the variation of the spanned dihedral angle causes in the bond distances, bond angles and the other dihedral angles. These energies were calculated using force-field expressions. The corrected profiles were fitted to a three-term Fourier expansion to derive the torsional parameters. Atomic charges for retro-inverso modified residues were derived from the rigorously calculated quantum mechanical electrostatic potential. Furthermore, the reliability of electrostatic models based on geometry-dependent charges and fixed charges has been examined.

  8. Theoretical studies of the mechanism of the action of the neurohypophyseal hormones. I. Molecular electrostatic potential (MEP) and molecular electrostatic field (MEF) maps of some vasopressin analogues

    NASA Astrophysics Data System (ADS)

    Liwo, Adam; Tempczyk, Anna; Grzonka, Zbigniew

    1989-09-01

    Continuing our theoretical studies of the oxytocin and vasopressin analogues, we have analysed the molecular electrostatic potential (MEP) and the norm of the molecular electrostatic field (MEF) of [1- β-mercaptopropionic acid]-arginine-vasopressin ([Mpa1]-AVP), [1-( β-mercapto- β,β-cyclopentamethylene)propionic acid]-arginine-vasopressin ([Cpp']-AVP), and [1-thiosalicylic acid]-arginine-vasopressin ([Ths']-AVP) whose low-energy conformations were calculated in our previous work. These compounds are known from experiment to exhibit different biological activity. The scalar fields mentioned determine the energy of interaction with either charged (MEP) or polar (MEF) species, the energy being in the second case either optimal or Boltzmann-averaged over all the possible orientations of the dipole moment versus the electrostatic field. The electrostatic interactions slowly vanish with distance and can therefore be considered to be the factor determining the molecular shape at greater distances, which can help in both predicting the interactions with the receptor at the stage of remote recognition and in finding the preferred directions of solvation by a polar solvent. In the analysis of the fields three techniques have been used: (i) the construction of maps in certain planes; (ii) the construction of maps on spheres centered in the charge center of the molecule under study and of poles chosen according to the main axes of the quadrupole moment; and (iii) the construction of surfaces corresponding to a given value of potential. The results obtained show that the shapes of both MEP and MEF are similar in the case of [Mpa1]-AVP and [Cpp1-AVP (biologically active), while some differences emerge when comparing these compounds with [Ths1]-AVP (inactive). It has also been found that both MEP and MEF depend even more strongly on conformation.

  9. Sprites as Luminous Columns of Ionization Produced by Quasi-Electrostatic Thundercloud Fields

    NASA Technical Reports Server (NTRS)

    Pasko, V. P.; Inan, U. S.; Bell, T. F.

    1996-01-01

    Quasi-electrostatic (QE) fields which exist above thunderclouds after lightning discharges can lead to the formation of columnar channels of breakdown ionization and carrot-like vertical luminous structures with typical transverse dimension approximately 5-10 km spaning an altitude range from approximately 80 km to well below approximately 50 km. The carrot-like forms closely resemble those observed in sprites. Results indicate that the appearance of optical emissions can be significantly delayed in time (approx. 1-20 ms) with respect to the causative lightning discharge.

  10. A Comparative Study of Transferable Aspherical Pseudoatom Databank and Classical Force Fields for Predicting Electrostatic Interactions in Molecular Dimers

    PubMed Central

    2015-01-01

    Accurate and fast evaluation of electrostatic interactions in molecular systems is one of the most challenging tasks in the rapidly advancing field of macromolecular chemistry and drug design. Electrostatic interactions are of crucial importance in biological systems. They are well represented by quantum mechanical methods; however, such calculations are computationally expensive. In this study, we have evaluated the University of Buffalo Pseudoatom Databank (UBDB)1,2 approach for approximation of electrostatic properties of macromolecules and their complexes. We selected the S663 and JSCH-20054 data sets (208 molecular complexes in total) for this study. These complexes represent a wide range of chemical and biological systems for which hydrogen bonding, electrostatic, and van der Waals interactions play important roles. Reference electrostatic energies were obtained directly from wave functions at the B3LYP/aug-cc-pVTZ level of theory using the SAPT (Symmetry-Adapted Perturbation Theory) scheme for calculation of electrostatic contributions to total intermolecular interaction energies. Electrostatic energies calculated on the basis of the UBDB were compared with corresponding reference results. Results were also compared with energies computed using a point charge model from popular force fields (AM1-BCC and RESP used in AMBER and CGenFF from CHARMM family). The energy trends are quite consistent (R2 ≈ 0.98) for the UBDB method as compared to the AMBER5 and CHARMM force field methods6(R2 ≈ 0.93 on average). The RSMEs do not exceed 3.2 kcal mol–1 for the UBDB and are in the range of 3.7–7.6 kcal mol–1 for the point charge models. We also investigated the discrepancies in electrostatic potentials and magnitudes of dipole moments among the tested methods. This study shows that estimation of electrostatic interaction energies using the UBDB databank is accurate and reasonably fast when compared to other known methods, which opens potential new applications

  11. Electrostatic field of the large fragment of Escherichia coli DNA polymerase I.

    PubMed

    Warwicker, J; Ollis, D; Richards, F M; Steitz, T A

    1985-12-05

    The electrostatic field of the large fragment of Escherichia coli DNA polymerase I (Klenow fragment) has been calculated by the finite difference procedure on a 2 A grid. The potential field is substantially negative at physiological pH (reflecting the net negative charge at this pH). The largest regions of positive potential are in the deep crevice of the C-terminal domain, which is the proposed binding site for the DNA substrate. Within the crevice, the electrostatic potential has a partly helical form. If the DNA is positioned to fulfil stereochemical requirements, then the positive potential generally follows the major groove and (to a lesser extent) the negative potential is in the minor groove. Such an arrangement could stabilize DNA configurations related by screw symmetry. The histidine residues of the Klenow fragment give the positive field of the groove a sensitivity to relatively small pH changes around neutrality. We suggest that the histidine residues could change their ionization states in response to DNA binding, and that this effect could contribute to the protein-DNA binding energy.

  12. Inhomogeneities of plasma density and electric field as sources of electrostatic turbulence in the auroral region

    SciTech Connect

    Ilyasov, Askar A.; Chernyshov, Alexander A. Mogilevsky, Mikhail M.; Golovchanskaya, Irina V. Kozelov, Boris V.

    2015-03-15

    Inhomogeneities of plasma density and non-uniform electric fields are compared as possible sources of a sort of electrostatic ion cyclotron waves that can be identified with broadband extremely low frequency electrostatic turbulence in the topside auroral ionosphere. Such waves are excited by inhomogeneous energy-density-driven instability. To gain a deeper insight in generation of these waves, computational modeling is performed with various plasma parameters. It is demonstrated that inhomogeneities of plasma density can give rise to this instability even in the absence of electric fields. By using both satellite-observed and model spatial distributions of plasma density and electric field in our modeling, we show that specific details of the spatial distributions are of minor importance for the wave generation. The solutions of the nonlocal inhomogeneous energy-density-driven dispersion relation are investigated for various ion-to-electron temperature ratios and directions of wave propagation. The relevance of the solutions to the observed spectra of broadband extremely low frequency emissions is shown.

  13. Geometry dependence of the electrostatic and thermal response of a carbon nanotube during field emission.

    PubMed

    Sanchez, Jaime A; Mengüç, M Pinar

    2008-02-20

    In this paper we present an analysis to simulate heating within an isolated carbon nanotube (CNT) attached to an etched tungsten tip during field emission of an electron beam. The length, radius, wall thickness and shape of the tip (closed with a hemispherical shape or open and flat) of the CNT and its separation distance from the flat surface are considered as variables. Using a finite element method, we predict the field enhancement, emission current and temperature of the CNT as a function of these parameters. The electrostatic and transient thermal analyses are integrated with the field-emission models based on the Fowler-Nordheim approximation and heating/cooling due to emitting energetic electrons (the Nottingham effect). These simulations suggest that the main mechanism responsible for heating of the CNT is Joule heating, which is significantly larger than the Nottingham effect. Results also indicate that the electrostatic characteristics of CNTs are very sensitive to the considered parameters whereas the transient thermal response is only a function of the CNT radius and wall thickness. Further, the thermal response of the CNT is independent of its geometry, meaning that, as long as a given set of geometrical conditions are present that result in a given emission current, the maximum temperature a CNT attains will be the same.

  14. Use of an electric field in an electrostatic liquid film radiator.

    PubMed

    Bankoff, S G; Griffing, E M; Schluter, R A

    2002-10-01

    Experimental and numerical work was performed to further the understanding of an electrostatic liquid film radiator (ELFR) that was originally proposed by Kim et al.(1) The ELFR design utilizes an electric field that exerts a normal force on the interface of a flowing film. The field lowers the pressure under the film in a space radiator and, thereby, prevents leakage through a puncture in the radiator wall. The flowing film is subject to the Taylor cone instability, whereby a cone of fluid forms underneath an electrode and sharpens until a jet of fluid is pulled toward the electrode and disintegrates into droplets. The critical potential for the instability is shown to be as much as an order of magnitude higher than that used in previous designs.(2) Furthermore, leak stoppage experiments indicate that the critical field is adequate to stop leaks in a working radiator.

  15. Anomalous self-generated electrostatic fields in nanosecond laser-plasma interaction

    SciTech Connect

    Lancia, L.; Antici, P.; Grech, M.; Weber, S.; Marques, J.-R.; Romagnani, L.; Bourgeois, N.; Audebert, P.; Fuchs, J.; Nakatsutsumi, M.; Bellue, A.; Feugeas, J.-L.; Nicolaie, Ph.; Tikhonchuk, V. T.; Grismayer, T.; Lin, T.; Nkonga, B.; Kodama, R.

    2011-03-15

    Electrostatic (E) fields associated with the interaction of a well-controlled, high-power, nanosecond laser pulse with an underdense plasma are diagnosed by proton radiography. Using a current three-dimensional wave propagation code equipped with nonlinear and nonlocal hydrodynamics, we can model the measured E-fields that are driven by the laser ponderomotive force in the region where the laser undergoes filamentation. However, strong fields of up to 110 MV/m measured in the first millimeter of propagation cannot be reproduced in the simulations. This could point to the presence of unexpected strong thermal electron pressure gradients possibly linked to ion acoustic turbulence, thus emphasizing the need for the development of full kinetic collisional simulations in order to properly model laser-plasma interaction in these strongly nonlinear conditions.

  16. Application of Gaussian Electrostatic Model (GEM) Distributed Multipoles in the AMOEBA Force Field.

    PubMed

    Cisneros, G Andrés

    2012-12-11

    We present the inclusion of distributed multipoles obtained from the Gaussian Electrostatic Model (GEM) into the AMOEBA force field. As a proof of principle, we have reparametrized water and alanine di-peptide. The GEM distributed multipoles (GEM-DM) have been obtained at the same levels of theory as those used for the original AMOEBA parametrization. The use of GEM allows the derivation of the distributed multipoles from the analytical fit to the molecular density or the numerical fit to the molecular electrostatic potential (mESP). In addition, GEM-DM are intrinsically finite of the highest order of the auxiliary basis used for the GEM fit. We also present the fitting of multipoles for the di-methyl imidazolium/chloride (DMIM(+)-Cl(-)) ionic liquid pair. Results for intermolecular Coulomb for all test systems show very good agreement. MD simulations for a reparametrized AMOEBA water model with GEM-DM provide results on par with the original AMOEBA force field for a series of bulk properties including liquid density and enthalpy of vaporization. A package for the calculation of GEM Hermite coefficients and derived distributed multipoles using the numerical procedure is also presented and released under the GNU public license.

  17. Preparation of CNTs rope by electrostatic and airflow field carding with high speed rotor spinning

    NASA Astrophysics Data System (ADS)

    Dai, J. F.; Liu, J. F.; Zou, J. T.; Dai, Y. L.

    2015-12-01

    The large-scale preparation of disorderly CNTs with a length larger than 3 mm using CVD method were aligned in polymer monomer airflow fields in a quartz tube with an internal diameter of 200 μm and a length of 1.5 m. The airflow aligned CNTs at the output end of the pipe connects to a copper nozzle with an electrostatic field of applied voltage 5x105 V/m and space length of 0.03 m, which were further realigned using via electrostatic spinning. End to end spray into the high speed rotor twisted single-stranded carbon nanotubes threads via rotor spinning technology. The essential component of this technique was the use of carbon nanotubes at a high rotory speed (200000 r/min) combined with the double twisting of filaments that were twisted together to increase the radial friction of the entire section. SEM micrography showed that carbon nanotube thread has a uniform diameter of approximately 200 μm. Its tensile strength was tested up to 2.7 Gpa, with a length of several meters.

  18. Temperature sensitivity analysis of polarity controlled electrostatically doped tunnel field-effect transistor

    NASA Astrophysics Data System (ADS)

    Nigam, Kaushal; Pandey, Sunil; Kondekar, P. N.; Sharma, Dheeraj

    2016-09-01

    The conventional tunnel field-effect transistors (TFETs) have shown potential to scale down in sub-22 nm regime due to its lower sub-threshold slope and robustness against short-channel effects (SCEs), however, sensitivity towards temperature variation is a major concern. Therefore, for the first time, we investigate temperature sensitivity analysis of a polarity controlled electrostatically doped tunnel field-effect transistor (ED-TFET). Different performance metrics and analog/RF figure-of-merits were considered and compared for both devices, and simulations were performed using Silvaco ATLAS device tool. We found that the variation in ON-state current in ED-TFET is almost temperature independent due to electrostatically doped mechanism, while, it increases in conventional TFET at higher temperature. Above room temperature, the variation in ION, IOFF, and SS sensitivity in ED-TFET are only 0.11%/K, 2.21%/K, and 0.63%/K, while, in conventional TFET the variations are 0.43%/K, 2.99%/K, and 0.71%/K, respectively. However, below room temperature, the variation in ED-TFET ION is 0.195%/K compared to 0.27%/K of conventional TFET. Moreover, it is analysed that the incomplete ionization effect in conventional TFET severely affects the drive current and the threshold voltage, while, ED-TFET remains unaffected. Hence, the proposed ED-TFET is less sensitive towards temperature variation and can be used for cryogenics as well as for high temperature applications.

  19. Equilibrium of a sphere inside a shell in an electrostatic field

    NASA Astrophysics Data System (ADS)

    Semenov, V. A.

    1984-10-01

    The ability of an axial mirror-symmetric electrostatic field to suspend a conducting sphere in a spherical dielectric shell is investigated theoretically and experimentally. The expression for the critical voltage required to suspend a sphere of given radius and dielectric constant is derived, extending the analysis of Bratukhin and Semenov (1982) for a nonconducting sphere to the conducting sphere. The experimental apparatus comprises a Wood's-metal sphere of diameter 0.3-1.5 mm, fitted into a polyethylene shell of diameter 2-3 mm and placed within a 6-mm-diameter Cu-wire electrode (at up to 20 kV) and between 16-mm-separated grounded horizontal Cu plates in a glass cell filled with castor oil and under a 170-Hz ac field (to damp electrohydrodynamic motion). The results are presented in a graph and shown to confirm the theoretical predictions.

  20. Effect of atom- and group-based truncations on biomolecules simulated with reaction-field electrostatics

    PubMed Central

    Ni, Boris

    2011-01-01

    The performance of the reaction-field method of electrostatics is tested in molecular dynamics simulations of protein human interleukin-4 and a short DNA fragment in explicit solvent. Two truncation schemes are considered: one based on the position of atomic charges in water molecules and the other on the position of groups of charges. The group-based truncation leads to the melting of the DNA double helix. In contrast, the atom-based truncation maintains the helical structure intact. Similarly for the protein, the group-based truncation leads to an unfolding at pH 2 while the atom-based truncation produces stable trajectories at low and normal pH, in agreement with experiment. Artificial repulsion between charged residues associated with the group-based truncation is identified as the microscopic reason behind unfolding of the protein. Implications of different truncation schemes in reaction-field simulations of biomolecules are discussed. PMID:21311933

  1. Magnetic field design for a Penning ion source for a 200 keV electrostatic accelerator

    NASA Astrophysics Data System (ADS)

    Fathi, A.; Feghhi, S. A. H.; Sadati, S. M.; Ebrahimibasabi, E.

    2017-04-01

    In this study, the structure of magnetic field for a Penning ion source has been designed and constructed with the use of permanent magnets. The ion source has been designed and constructed for a 200 keV electrostatic accelerator. With using CST Studio Suite, the magnetic field profile inside the ion source was simulated and an appropriate magnetic system was designed to improve particle confinement. Designed system consists of two ring magnets with 9 mm distance from each other around the anode. The ion source was constructed and the cylindrical magnet and designed magnetic system were tested on the ion source. The results showed that the ignition voltage for ion source with the designed magnetic system is almost 300 V lower than the ion source with the cylindrical magnet. Better particle confinement causes lower voltage discharge to occur.

  2. Tailoring Nanoscale Morphology of Polymer:Fullerene Blends Using Electrostatic Field.

    PubMed

    Elshobaki, Moneim; Gebhardt, Ryan; Carr, John; Lindemann, William; Wang, Wenjie; Grieser, Eric; Venkatesan, Swaminathan; Ngo, Evan; Bhattacharjee, Ujjal; Strzalka, Joseph; Jiang, Zhang; Qiao, Qiquan; Petrich, Jacob; Vaknin, David; Chaudhary, Sumit

    2017-01-25

    To tailor the nanomorphology in polymer/fullerene blends, we study the effect of electrostatic field (E-field) on the solidification of poly(3-hexylthiophene-2, 5-diyl) (P3HT):[6,6]-phenyl-C61-butyric acid methyl ester (PC60BM) bulk heterojunction (BHJ). In addition to control; wet P3HT:PC60BM thin films were exposed to E-field of Van de Graaff (VDG) generator at three different directions-horizontal (H), tilted (T), and vertical (V)-relative to the plane of the substrate. Surface and bulk characterizations of the field-treated BHJs affirmed that fullerene molecules can easily penetrate the spaghetti-like P3HT and move up and down following the E-field. Using E-field treatment, we achieved favorable morphologies with efficient charge separation, transport, and collection. We improve; (1) the hole mobility values up to 19.4 × 10(-4) ± 1.6 × 10(-4) cm(2) V(-1) s(-1) and (2) the power conversion efficiency (PCE) of conventional and inverted OPVs up to 2.58 ± 0.02% and 4.1 ± 0.40%, respectively. This E-field approach can serve as a new morphology-tuning technique, which is generally applicable to other polymer-fullerene systems.

  3. Electrostatic melting in a single-molecule field-effect transistor with applications in genomic identification

    NASA Astrophysics Data System (ADS)

    Vernick, Sefi; Trocchia, Scott M.; Warren, Steven B.; Young, Erik F.; Bouilly, Delphine; Gonzalez, Ruben L.; Nuckolls, Colin; Shepard, Kenneth L.

    2017-05-01

    The study of biomolecular interactions at the single-molecule level holds great potential for both basic science and biotechnology applications. Single-molecule studies often rely on fluorescence-based reporting, with signal levels limited by photon emission from single optical reporters. The point-functionalized carbon nanotube transistor, known as the single-molecule field-effect transistor, is a bioelectronics alternative based on intrinsic molecular charge that offers significantly higher signal levels for detection. Such devices are effective for characterizing DNA hybridization kinetics and thermodynamics and enabling emerging applications in genomic identification. In this work, we show that hybridization kinetics can be directly controlled by electrostatic bias applied between the device and the surrounding electrolyte. We perform the first single-molecule experiments demonstrating the use of electrostatics to control molecular binding. Using bias as a proxy for temperature, we demonstrate the feasibility of detecting various concentrations of 20-nt target sequences from the Ebolavirus nucleoprotein gene in a constant-temperature environment.

  4. Electrostatic mode associated with the pinch velocity in reversed field pinch simulations

    SciTech Connect

    Delzanno, Gian Luca; Finn, John M.; Chacon, Luis

    2008-12-15

    The existence of a new phenomenon in reversed field pinch (RFP) simulations related to the equilibrium pinch flow is discussed. This behavior is due to the inward equilibrium flow, but is strongly affected by boundary conditions on the perturbed azimuthal flow. It is important to understand and control this mechanism in single helicity simulations of RFPs. This mechanism can be explained in terms of an electrostatic instability related to a mode which can occur in fluid dynamics. In a simple linear model, it is shown that the mode, which is related to the inward advection of angular momentum from the edge, can be stabilized by using homogeneous Dirichlet (no-slip) boundary conditions at the wall. Behavior due to this mode is present in nonlinear simulations with zero-viscous-stress boundary conditions on the tangential velocity at the wall and, even in the presence of the usual magnetohydrodynamic modes, this mode can dominate the nonlinear dynamics of the velocity. In nonlinear simulations with Dirichlet boundary conditions on the tangential velocity, behavior associated with this electrostatic mode is not observed.

  5. Electrostatic mode associated with the pinch velocity in reversed field pinch simulations

    SciTech Connect

    Delzanno, Gian Luca; Chacon, Luis; Finn, John M.

    2008-01-01

    The existence of a new phenomenon in reversed field pinch (RFP) simulations related to the equilibrium pinch flow is discussed. This behavior is due to the inward equilibrium flow, but is strongly affected by boundary conditions on the perturbed azimuthal flow. It is important to understand and control this mechanism in single helicity simulations of RFPs. This mechanism can be explained in terms of an electrostatic instability related to a mode which can occur in fluid dynamics. In a simple linear model, it is shown that the mode, which is related to the inward advection of angular momentum from the edge, can be stabilized by using homogeneous Dirichlet (no-slip) boundary conditions at the wall. Behavior due to this mode is present in nonlinear simulations with zero-viscous-stress boundary conditions on the tangential velocity at the wall and, even in the presence of the usual magnetohydrodynamic modes, this mode can dominate the nonlinear dynamics of the velocity. In nonlinear simulations with Dirichlet boundary conditions on the tangential velocity, behavior associated with this electrostatic mode is not observed.

  6. Long- and Short-Range Electrostatic Fields in GFP Mutants: Implications for Spectral Tuning

    PubMed Central

    Drobizhev, M.; Callis, P. R.; Nifosì, R.; Wicks, G.; Stoltzfus, C.; Barnett, L.; Hughes, T. E.; Sullivan, P.; Rebane, A.

    2015-01-01

    The majority of protein functions are governed by their internal local electrostatics. Quantitative information about these interactions can shed light on how proteins work and allow for improving/altering their performance. Green fluorescent protein (GFP) and its mutation variants provide unique optical windows for interrogation of internal electric fields, thanks to the intrinsic fluorophore group formed inside them. Here we use an all-optical method, based on the independent measurements of transition frequency and one- and two-photon absorption cross sections in a number of GFP mutants to evaluate these internal electric fields. Two physical models based on the quadratic Stark effect, either with or without taking into account structural (bond-length) changes of the chromophore in varying field, allow us to separately evaluate the long-range and the total effective (short- and long-range) fields. Both types of the field quantitatively agree with the results of independent molecular dynamic simulations, justifying our method of measurement. PMID:26286372

  7. Improved mapping of planetary gravitational field with an electrostatic accelerometer/gradiometer

    NASA Astrophysics Data System (ADS)

    Foulon, Bernard; Huynh, Phuong-Anh; Liorzou, Francoise; Christophe, Bruno; Hardy, Emilie; Boulanger, Damien; Lebat, Vincent; Perrot, Eddy

    2015-04-01

    ONERA has a proven record spanning several years in developing the most accurate accelerometers for geodesy missions. They are still operational in the GRACE mission and their successors for the GRACE-FO mission will fly in 2017. Finally, the GOCE mission has shown the benefit of using a gradiometer for the direct measurement of the gravity field. Now, ONERA proposes a new accelerometer design, MicroSTAR, for interplanetary missions. This design based on the same technology as for the GRACE and GOCE space missions, with the notable addition of a bias rejection system, has a reduced mass and consumption. The accelerometer is embarked on Uranus Pathfinder (mission proposal for Cosmic M4) as up-scope instrument to achieve two scientific objectives: 1) to determine the gravity fields of Uranus and the satellites, allowing for a better understanding of the planet interior composition, 2) to test gravity at the largest possible length scales to search for deviations from General Relativity. The success of using accelerometer for geodesy mission could be imported in the planetary science field. The poster details the accuracy which can be achieved on the gravity potential field according to different accelerometer configurations. It describes the instrument and its integration inside an interplanetary probe. Finally, it explains the benefit of using this electrostatic accelerometer complementary to radio science technology for improved planetary gravitational field measurements.

  8. Mixed quantum-classical molecular dynamics simulation of vibrational relaxation of ions in an electrostatic field.

    PubMed

    Koutselos, Andreas D

    2006-12-28

    The vibrational relaxation of ions in low-density gases under the action of an electrostatic field is reproduced through a molecular dynamics simulation method. The vibration is treated though quantum mechanics and the remaining degrees of freedom are considered classical. The procedure is tested through comparison against analytic results for a two-dimensional quantum model and by studying energy exchange during binary ion-atom collisions. Finally, the method has been applied successfully to the calculation of the mobility and the vibrational relaxation rate of O2+ in Kr as a function of the mean collision energy using a model interaction potential that reproduces the potential minimum of a previously known ab initio potential surface. The calculation of the steady mean vibrational motion of the ions in (flow) drift tubes seems straightforward, though at the expense of large amounts of computer time.

  9. Gyrokinetic Simulations of Electrostatic Turbulence Reduction due to Radial Electric Field Shear in DIII-D

    NASA Astrophysics Data System (ADS)

    Taimourzadeh, Sam; Holod, Ihor; Lin, Zhihong; Nazikian, Raffi

    2015-11-01

    It has been demonstrated that edge localized modes (ELMs) can be fully suppressed in DIII-D H-mode plasmas with the application of resonant magnetic perturbations (RMPs), and that there is a corresponding reduction of pedestal gradients, changes in rotation, and changes in the radial electric field (Er) profile. However, with the application of RMPs there is also an increase in short wavelength, electrostatic turbulence on top of the pedestal, as observed with BES, DBS, and other fluctuation diagnostics. The effects of Er shear on this turbulence, is investigated using gyrokinetic simulations via the gyrokinetic toroidal code (GTC) for in DIII-D shot 158103, at times 3750 ms (RMP on, ELM active) and 3050 ms (RMP on, ELM suppressed).

  10. Improvement of Electrostatic Discharge Protection by Introducing a Spindt-Type Silicon Field Emission Device

    NASA Astrophysics Data System (ADS)

    Chang, Liann-Be; Ferng, Yi-Cherng; Liao, Jhong-Wei; Lin, Ching-Chi

    2012-04-01

    In this paper, an original Spindt-type silicon field emission device (FED) with electrostatic discharge (ESD) regulation capability is proposed. The fabricated FED characteristics, including process parameters, capacitance-voltage (C-V), current-voltage (I-V), and frequency response, are investigated. To verify its capability of ESD protection, we replace the metal oxide varistor (MOV) in a state-of-the-art protection configuration with the fabricated FED under the application conditions of system-level ESD tests. The measured results show that the proposed ESD protection circuit composed of a prestage gas arrestor, an intermediate resistor, and an introduced FED can suppress an injected ESD pulse voltage of 6000 to 3193 V, a reduction of 46.8%, whereas suppression is to 5606 V, a reduction of 6.57%, when using only a gas arrestor.

  11. Dispersive FDTD analysis of induced electric field in human models due to electrostatic discharge.

    PubMed

    Hirata, Akimasa; Nagai, Toshihiro; Koyama, Teruyoshi; Hattori, Junya; Chan, Kwok Hung; Kavet, Robert

    2012-07-07

    Contact currents flow from/into a charged human body when touching a grounded conductive object. An electrostatic discharge (ESD) or spark may occur just before contact or upon release. The current may stimulate muscles and peripheral nerves. In order to clarify the difference in the induced electric field between different sized human models, the in-situ electric fields were computed in anatomically based models of adults and a child for a contact current in a human body following ESD. A dispersive finite-difference time-domain method was used, in which biological tissue is assumed to obey a four-pole Debye model. From our computational results, the first peak of the discharge current was almost identical across adult and child models. The decay of the induced current in the child was also faster due mainly to its smaller body capacitance compared to the adult models. The induced electric fields in the forefingers were comparable across different models. However, the electric field induced in the arm of the child model was found to be greater than that in the adult models primarily because of its smaller cross-sectional area. The tendency for greater doses in the child has also been reported for power frequency sinusoidal contact current exposures as reported by other investigators.

  12. Electrostatic induction of the electric field into free-flow electrophoresis devices.

    PubMed

    Janasek, Dirk; Schilling, Michael; Manz, Andreas; Franzke, Joachim

    2006-06-01

    The electrostatic induction of an applied voltage causes electrophoretic separation under free-flow conditions and no electrolysis or electric current flowing between the metal electrodes was observed.

  13. Field-aligned electrostatic potential differences on the Martian night side

    NASA Astrophysics Data System (ADS)

    Lillis, Rob; Collinson, Glyn; Mitchell, David

    2017-04-01

    Field-aligned electrostatic potential differences on the Martian night side above 170 km can be inferred with the aid of a kinetic electron transport model and in a statistical sense, by energy-dependent angular shifts in electron loss cones measured in Mars orbit. Potentials between 170 km and 400 km derived from pitch angle distributions measured by the Mars Global Surveyor (MGS) Magnetometer/ Electron Reflectometer experiment (MAG/ER) at 2 a.m. local time are typically small (-10 V to 10 V) but can reach magnitudes of >100 V. Geographically, the strongest negative potential differences (with mean values up to -50 V) are preferentially observed at the boundaries between open and closed strong magnetic field regions, while positive potential differences are preferentially observed further from open field lines. These characteristics may reflect current systems closing at high altitude through cross-tail currents and at low altitude in the conducting night side ionosphere. We will present a synthesis of potentials derived from pitch angle distributions measured by both MGS MAG/ER as mentioned above, and by the MAVEN Solar Wind Electron Analyzer (SWEA) collected at a range of local times and altitudes.

  14. Kinetics of charged particles in a high-voltage gas discharge in a nonuniform electrostatic field

    NASA Astrophysics Data System (ADS)

    Kolpakov, V. A.; Krichevskii, S. V.; Markushin, M. A.

    2017-01-01

    A high-voltage gas discharge is of interest as a possible means of generating directed flows of low-temperature plasma in the off-electrode space distinguished by its original features [1-4]. We propose a model for calculating the trajectories of charges particles in a high-voltage gas discharge in nitrogen at a pressure of 0.15 Torr existing in a nonuniform electrostatic field and the strength of this field. Based on the results of our calculations, we supplement and refine the extensive experimental data concerning the investigation of such a discharge published in [1, 2, 5-8]; good agreement between the theory and experiment has been achieved. The discharge burning is initiated and maintained through bulk electron-impact ionization and ion-electron emission. We have determined the sizes of the cathode surface regions responsible for these processes, including the sizes of the axial zone involved in the discharge generation. The main effect determining the kinetics of charged particles consists in a sharp decrease in the strength of the field under consideration outside the interelectrode space, which allows a free motion of charges with specific energies and trajectories to be generated in it. The simulation results confirm that complex electrode systems that allow directed plasma flows to be generated at a discharge current of hundreds or thousands of milliamperes and a voltage on the electrodes of 0.3-1 kV can be implemented in practice [3, 9, 10].

  15. On the state selection of linear triatomic molecules by electrostatic hexapole fields.

    PubMed

    Tsai, Po-Yu

    2016-09-14

    Electrostatic hexapole state-selector is a versatile tool in experimental stereodynamics. The requirement of appropriate models to correctly predict the behavior of molecules in the hexapole motivated us to realize a treatment that predicts the Stark effect of linear triatomic molecules with rotational doublet states. Various perturbative approximations are conventionally adopted to obtain analytic Stark energy derivatives of a truncated Hamiltonian matrix, without utilizing numerical diagonalization of the full Hamiltonian matrix. By including both the low and high field effects, which were alternatively ignored in the analytical formulae of such approximate approaches, herein we demonstrate that the performance of hexapole state selector to linear triatomic molecules can be appropriately predicted via Van Vleck transformation. This method can provide analytic Stark energy derivatives that are acceptably in consistent with the ones obtained via numerical diagonalization of the full Hamiltonian matrix. Particularly, this work is suitable for v2 = 1 level of linear triatomic molecules, due to the following reasons: (1) the Stark energy derivative and the molecular orientation as a function of the electric field are expressed in analytical formulae, hence it is suitable for implementation without involving numerical diagonalization of the full Hamiltonian matrix; (2) a better prediction of the focusing curves with respect to conventional analytical treatments is provided, allowing a reliable determination of the selected state compositions and molecular orientation.

  16. Gyrokinetic theory of electrostatic lower-hybrid drift instabilities in a current sheet with guide field

    SciTech Connect

    Tummel, K.; Chen, L.; Wang, Z.; Wang, X. Y.; Lin, Y.

    2014-05-15

    A kinetic electrostatic eigenvalue equation for the lower-hybrid drift instability (LHDI) in a thin Harris current sheet with a guide field is derived based on the gyrokinetic electron and fully kinetic ion(GeFi) description. Three-dimensional nonlocal analyses are carried out to investigate the influence of a guide field on the stabilization of the LHDI by finite parallel wavenumber, k{sub ∥}. Detailed stability properties are first analyzed locally, and then as a nonlocal eigenvalue problem. Our results indicate that at large equilibrium drift velocities, the LHDI is further destabilized by finite k{sub ∥} in the short-wavelength domain. This is demonstrated in a local stability analysis and confirmed by the peak in the eigenfunction amplitude. We find the most unstable modes localized at the current sheet edges, and our results agree well with simulations employing the GeFi code developed by Lin et al. [Plasma Phys. Controlled Fusion 47, 657 (2005); Plasma Phys. Controlled Fusion 53, 054013 (2011)].

  17. Interaction of field-aligned cold plasma flows with an equatorially-trapped hot plasma - Electrostatic shock formation

    NASA Technical Reports Server (NTRS)

    Singh, Nagendra

    1993-01-01

    Effects of equatorially trapped hot plasma on the highly supersonic cold-plasma flow occurring during early stage plasmaspheric refilling are studied by means of numerical simulations. It is shown that the equatorially trapped hot ions set up a potential barrier for the cold ion beams and facilitate formation of electrostatic shocks by reflecting them from the equatorial region. Simulations with and without the hot plasma show different flow properties; the formation of electrostatic shocks occur only in the former case. The simulation with the hot plasma also reveals that the magnetic trapping in conjunction with the evolution of the electrostatic potential barrier produces ion velocity distribution functions consisting of a cold core and a hot ring in the perpendicular velocity. Such a distribution function provides a source of free energy for equatorial waves. The corresponding electron population is warm and field-aligned.

  18. Interaction of field-aligned cold plasma flows with an equatorially-trapped hot plasma - Electrostatic shock formation

    NASA Technical Reports Server (NTRS)

    Singh, Nagendra

    1993-01-01

    Effects of equatorially trapped hot plasma on the highly supersonic cold-plasma flow occurring during early stage plasmaspheric refilling are studied by means of numerical simulations. It is shown that the equatorially trapped hot ions set up a potential barrier for the cold ion beams and facilitate formation of electrostatic shocks by reflecting them from the equatorial region. Simulations with and without the hot plasma show different flow properties; the formation of electrostatic shocks occur only in the former case. The simulation with the hot plasma also reveals that the magnetic trapping in conjunction with the evolution of the electrostatic potential barrier produces ion velocity distribution functions consisting of a cold core and a hot ring in the perpendicular velocity. Such a distribution function provides a source of free energy for equatorial waves. The corresponding electron population is warm and field-aligned.

  19. Effects of high-voltage electrostatic fields on the quality of tilapia meat during refrigeration.

    PubMed

    Hsieh, Chang-Wei; Lai, Cheng-Hung; Lee, Chia-Hsin; Ko, Wen-Ching

    2011-08-01

    Fresh fish is typically brought to market refrigerated at approximately 4 °C, R-storage. A storage method has been devised that combines refrigeration with a high-voltage electrostatic field (100 kV/m; E-storage). It was developed to improve the quality and prolong the shelf life of foods. This study investigated changes in the freshness of tilapia meat under E-storage conditions. The total viable count of tilapia reached 10⁷ CFU/g on the 7th d of refrigeration in R-storage. By the 6th d, K-value had increased from 20% to 61.7% for E-storage and to 94.7% for R-storage. Volatile basic nitrogen had increased from 12.54 mg/100 g to about 24.34 and 25.03 mg/100 g for R- and E-storage (on the 7th and 10th d), respectively. The sensory assessment also indicated that E-storage yielded an improvement in quality over that of R-storage. Practical application of the study model has the potential to prolong the freshness of fish.

  20. Enhanced Deposition by Electrostatic Field-Assistance Aggravating Diesel Exhaust Aerosol Toxicity for Human Lung Cells.

    PubMed

    Stoehr, Linda C; Madl, Pierre; Boyles, Matthew S P; Zauner, Roland; Wimmer, Monika; Wiegand, Harald; Andosch, Ancuela; Kasper, Gerhard; Pesch, Markus; Lütz-Meindl, Ursula; Himly, Martin; Duschl, Albert

    2015-07-21

    Air pollution is associated with increased risk of cardiovascular and pulmonary diseases, but conventional air quality monitoring gives no information about biological consequences. Exposing human lung cells at the air-liquid interface (ALI) to ambient aerosol could help identify acute biological responses. This study investigated electrode-assisted deposition of diesel exhaust aerosol (DEA) on human lung epithelial cells (A549) in a prototype exposure chamber. A549 cells were exposed to DEA at the ALI and under submerged conditions in different electrostatic fields (EFs) and were assessed for cell viability, membrane integrity, and IL-8 secretion. Qualitative differences of the DEA and its deposition under different EFs were characterized using scanning mobility particle sizer (SMPS) measurements, transmission electron microscopy (TEM), and electron energy loss spectroscopy (EELS). Upon exposure to DEA only, cell viability decreased and membrane impairment increased for cells at the ALI; submerged cells were unaffected. These responses were enhanced upon application of an EF, as was DEA deposition. No adverse effects were observed for filtered DEA or air only, confirming particle-induced responses. The prototype exposure chamber proved suitable for testing DEA-induced biological responses of cells at the ALI using electrode-assisted deposition and may be useful for analysis of other air pollutants.

  1. Multipolar electrostatics.

    PubMed

    Cardamone, Salvatore; Hughes, Timothy J; Popelier, Paul L A

    2014-06-14

    Atomistic simulation of chemical systems is currently limited by the elementary description of electrostatics that atomic point-charges offer. Unfortunately, a model of one point-charge for each atom fails to capture the anisotropic nature of electronic features such as lone pairs or π-systems. Higher order electrostatic terms, such as those offered by a multipole moment expansion, naturally recover these important electronic features. The question remains as to why such a description has not yet been widely adopted by popular molecular mechanics force fields. There are two widely-held misconceptions about the more rigorous formalism of multipolar electrostatics: (1) Accuracy: the implementation of multipole moments, compared to point-charges, offers little to no advantage in terms of an accurate representation of a system's energetics, structure and dynamics. (2) Efficiency: atomistic simulation using multipole moments is computationally prohibitive compared to simulation using point-charges. Whilst the second of these may have found some basis when computational power was a limiting factor, the first has no theoretical grounding. In the current work, we disprove the two statements above and systematically demonstrate that multipole moments are not discredited by either. We hope that this perspective will help in catalysing the transition to more realistic electrostatic modelling, to be adopted by popular molecular simulation software.

  2. Optical transitions in semiconductor nanospherical core/shell/shell heterostructure in the presence of radial electrostatic field

    NASA Astrophysics Data System (ADS)

    Baghdasaryan, D. A.; Hayrapetyan, D. B.; Harutyunyan, V. A.

    2017-04-01

    The electronic states and optical properties of spherical nanolayer in the presence of the electrostatic radial field in the strong size quantization regime have been considered. Both analytical and numerical methods have been applied to the problem of one-electron states in the system. According to the intensity of the external electrostatic field, three regimes have been distinguished: week, intermediate and strong. Perturbative approach have been applied to the case of week, WKB to the case of intermediate and variation approach to the case of strong field intensities. The analytical dependencies of the one electron energy and wave function on the electric field value and geometrical parameters of the nanolayer have been achieved. The comparison of the results obtained by the analytical method with the results of the numerical method have been made. The interband and intraband optical transitions caused by incident optical light polarized in z direction have been considered in this system. The selection rules for this transitions have been obtained. The dependence of the absorption coefficient on the energy of incident light for both cases of interband and intraband transitions for every regime of the electrostatic field value have been received.

  3. ELECTROSTATIC POWER GENERATOR.

    DTIC Science & Technology

    ELECTROSTATIC GENERATORS , POWER EQUIPMENT, ELECTRIC GOVERNORS, CIRCUITS, VACUUM SEALS, ELECTRICAL INSULATION, VACUUM, ELECTRODES, FINISHES, SURFACE...FINISHING, SURFACE PROPERTIES, HARDNESS, PULSE GENERATORS , TRANSFORMERS, FIELD EMISSION.

  4. ELECTROSTATIC POWER GENERATOR.

    DTIC Science & Technology

    ELECTROSTATIC GENERATORS , POWER EQUIPMENT, ELECTRICAL INSULATION, FIELD EMISSION, ELECTRODES, VACUUM, SURFACE PROPERTIES, ANODES, CATHODES, POLISHES...DIELECTRICS, COATINGS, PRESSURE, HARDNESS, PULSE GENERATORS , TRANSFORMERS, VACUUM SEALS, EQUATIONS.

  5. Electrostatics of proteins in dielectric solvent continua. I. An accurate and efficient reaction field description

    SciTech Connect

    Bauer, Sebastian; Mathias, Gerald; Tavan, Paul

    2014-03-14

    We present a reaction field (RF) method which accurately solves the Poisson equation for proteins embedded in dielectric solvent continua at a computational effort comparable to that of an electrostatics calculation with polarizable molecular mechanics (MM) force fields. The method combines an approach originally suggested by Egwolf and Tavan [J. Chem. Phys. 118, 2039 (2003)] with concepts generalizing the Born solution [Z. Phys. 1, 45 (1920)] for a solvated ion. First, we derive an exact representation according to which the sources of the RF potential and energy are inducible atomic anti-polarization densities and atomic shielding charge distributions. Modeling these atomic densities by Gaussians leads to an approximate representation. Here, the strengths of the Gaussian shielding charge distributions are directly given in terms of the static partial charges as defined, e.g., by standard MM force fields for the various atom types, whereas the strengths of the Gaussian anti-polarization densities are calculated by a self-consistency iteration. The atomic volumes are also described by Gaussians. To account for covalently overlapping atoms, their effective volumes are calculated by another self-consistency procedure, which guarantees that the dielectric function ε(r) is close to one everywhere inside the protein. The Gaussian widths σ{sub i} of the atoms i are parameters of the RF approximation. The remarkable accuracy of the method is demonstrated by comparison with Kirkwood's analytical solution for a spherical protein [J. Chem. Phys. 2, 351 (1934)] and with computationally expensive grid-based numerical solutions for simple model systems in dielectric continua including a di-peptide (Ac-Ala-NHMe) as modeled by a standard MM force field. The latter example shows how weakly the RF conformational free energy landscape depends on the parameters σ{sub i}. A summarizing discussion highlights the achievements of the new theory and of its approximate solution

  6. Electrostatics of proteins in dielectric solvent continua. I. An accurate and efficient reaction field description.

    PubMed

    Bauer, Sebastian; Mathias, Gerald; Tavan, Paul

    2014-03-14

    We present a reaction field (RF) method which accurately solves the Poisson equation for proteins embedded in dielectric solvent continua at a computational effort comparable to that of an electrostatics calculation with polarizable molecular mechanics (MM) force fields. The method combines an approach originally suggested by Egwolf and Tavan [J. Chem. Phys. 118, 2039 (2003)] with concepts generalizing the Born solution [Z. Phys. 1, 45 (1920)] for a solvated ion. First, we derive an exact representation according to which the sources of the RF potential and energy are inducible atomic anti-polarization densities and atomic shielding charge distributions. Modeling these atomic densities by Gaussians leads to an approximate representation. Here, the strengths of the Gaussian shielding charge distributions are directly given in terms of the static partial charges as defined, e.g., by standard MM force fields for the various atom types, whereas the strengths of the Gaussian anti-polarization densities are calculated by a self-consistency iteration. The atomic volumes are also described by Gaussians. To account for covalently overlapping atoms, their effective volumes are calculated by another self-consistency procedure, which guarantees that the dielectric function ε(r) is close to one everywhere inside the protein. The Gaussian widths σ(i) of the atoms i are parameters of the RF approximation. The remarkable accuracy of the method is demonstrated by comparison with Kirkwood's analytical solution for a spherical protein [J. Chem. Phys. 2, 351 (1934)] and with computationally expensive grid-based numerical solutions for simple model systems in dielectric continua including a di-peptide (Ac-Ala-NHMe) as modeled by a standard MM force field. The latter example shows how weakly the RF conformational free energy landscape depends on the parameters σ(i). A summarizing discussion highlights the achievements of the new theory and of its approximate solution particularly by

  7. Two-dimensional infrared spectroscopy as a probe of the solvent electrostatic field for a twelve residue peptide.

    PubMed

    Wang, Jianping; Zhuang, Wei; Mukamel, Shaul; Hochstrasser, Robin

    2008-05-15

    The linear IR and two-dimensional (2D) IR spectra of the amide-I modes of the 12-residue beta-hairpin peptide tryptophan zipper-2 (SWTWENGKWTWK) and its two 13C isotopomers were simulated, with local mode frequencies evaluated by two solution-phase peptide amide-I frequency maps proposed recently: an electrostatic potential map and an electrostatic field map. Both maps predict a set of nondegenerate local amide-I mode transition energies for the hairpin. Spectral simulations using both maps predict the main spectral features of the linear IR and 2D IR experimental results of the (13)C-labeled and -unlabeled hairpin. The radial distribution functions obtained using trajectories from classical molecular dynamics simulations demonstrate different water distributions at different sites of the hairpin. Our results suggest that the observed difference of the (13)C-shifted band, including its peak position and frequency distributions for different isotopomers, in both linear IR and 2D IR spectra, is likely to be due to the difference in the local environment of the solvated peptide. Ab initio density functional theory calculations show a residue-independent (13)C shift of the amide-I mode, further supporting the result. The variations of these shifts are attributed to the residue level heterogeneity of the electrostatic environment of the peptide. Our results show that 2D IR of peptide with single (13)C isotopic labeling can be used to probe the electrostatic environment of the peptide local structure.

  8. Combining the lattice-sum and reaction-field approaches for evaluating long-range electrostatic interactions in molecular simulations.

    PubMed

    Heinz, Tim N; Hünenberger, Philippe H

    2005-07-15

    A new scheme, the lattice-sum-emulated reaction-field (LSERF) method, is presented that combines the lattice-sum (LS) and reaction-field (RF) approaches for evaluating electrostatic interactions in molecular simulations. More precisely, the LSERF scheme emulates a RF calculation (based on an atomic cutoff) via the LS machinery. This is achieved by changing the form of the electrostatic interactions in a standard LS calculation (Coulombic) to the form corresponding to RF electrostatics (Coulombic plus quadratic reaction-field correction term, truncated at the cutoff distance). It is shown (both analytically and numerically) that in the limit of infinite reciprocal-space accuracy, (i) the LSERF scheme with a finite reaction-field cutoff and a given reaction-field permittivity is identical to the RF scheme with the same parameters (and an atomic cutoff), and (ii) the LSERF scheme is identical to the LS scheme in the limit of an infinite reaction-field cutoff, irrespective of the reaction-field permittivity. This new scheme offers two key advantages: (i) from a conceptual point of view, it shows that there is a continuity between the RF and LS schemes and unifies them into a common framework; (ii) from a practical point of view, it allows us to perform RF calculations with arbitrarily large reaction-field cutoff distances for the same computational costs as a corresponding LS calculation. The optimal choice for the cutoff will be the one that achieves the best compromise between artifacts arising from the dielectric heterogeneity of the system (short cutoff) and its artificial periodicity (long cutoff). The implementation of the LSERF method is extremely easy, requiring only very limited modifications of any standard LS code. For practical applications to biomolecular systems, the use of the LSERF scheme with large reaction-field cutoff distances is expected to represent a significant improvement over the current RF simulations involving comparatively much shorter

  9. High volume-high value usage of flue gas desulfurization (FGD) by-products in underground mines: Phase 2, Field investigations. Quarterly report, October 1--December 31, 1996

    SciTech Connect

    1996-12-31

    In this quarter, activity focused on the placement of Flue Gas Desulfurization (FGD) grout into auger holes at the Sunny Ridge Mining Co. site. As discussed in previous reports, the grout was prepared using fluidized bed combustion (FBC) by-product obtained from the Costain Coal Company. The grout was thoroughly mixed with water and transferred to a concrete pumping truck. The nozzle on the pumper truck was attached to PVC pipe through which the grout was pumped into the auger holes. The first field test involved the placement of a very high slump, flowable grout into auger holes sing a simple, earthern bulkhead. These tests were conducted to explore the flowability of the grout. The second series of test was conducted with a lower-slump, higher-viscosity material pumped at high pressure and using sandbags as a bulkhead. The goal of these tests was to examine the feasibility of pressure grouting to completely fill auger holes with a material that will exhibit high long-term strength because of this low initial water content. Although there were many problems encountered during the field demonstration, these initial tests were, overall, successful. It was shown that a high-slump grout can be pumped the length of the auger holes, and can be successfully placed in holes containing standing water. Furthermore, this can be accomplished using available concrete emplacement equipment. In contrast, the pressure grouting proved more challenging than emplacement of the flowable grout mainly because of pipe-joint failures and difficulties in working the stiff, high-viscosity grout; the amount of water added to the mix is critical when placing this type of material. Cylinders of grout for compressive strength testing were prepared during field demonstration, and cores of the in situ hardened grout will be recovered after a minimum of 30 days. Additional field demonstration will focus on improving the procedure for placement of the flowable grout.

  10. Vibrational spectroscopic determination of local solvent electric field, solute-solvent electrostatic interaction energy, and their fluctuation amplitudes.

    PubMed

    Lee, Hochan; Lee, Gayeon; Jeon, Jonggu; Cho, Minhaeng

    2012-01-12

    IR probes have been extensively used to monitor local electrostatic and solvation dynamics. Particularly, their vibrational frequencies are highly sensitive to local solvent electric field around an IR probe. Here, we show that the experimentally measured vibrational frequency shifts can be inversely used to determine local electric potential distribution and solute-solvent electrostatic interaction energy. In addition, the upper limits of their fluctuation amplitudes are estimated by using the vibrational bandwidths. Applying this method to fully deuterated N-methylacetamide (NMA) in D(2)O and examining the solvatochromic effects on the amide I' and II' mode frequencies, we found that the solvent electric potential difference between O(═C) and D(-N) atoms of the peptide bond is about 5.4 V, and thus, the approximate solvent electric field produced by surrounding water molecules on the NMA is 172 MV/cm on average if the molecular geometry is taken into account. The solute-solvent electrostatic interaction energy is estimated to be -137 kJ/mol, by considering electric dipole-electric field interaction. Furthermore, their root-mean-square fluctuation amplitudes are as large as 1.6 V, 52 MV/cm, and 41 kJ/mol, respectively. We found that the water electric potential on a peptide bond is spatially nonhomogeneous and that the fluctuation in the electrostatic peptide-water interaction energy is about 10 times larger than the thermal energy at room temperature. This indicates that the peptide-solvent interactions are indeed important for the activation of chemical reactions in aqueous solution.

  11. High volume production of nanostructured materials

    DOEpatents

    Ripley, Edward B [Knoxville, TN; Morrell, Jonathan S [Knoxville, TN; Seals, Roland D [Oak Ridge, TN; Ludtka, Gerard M [Oak Ridge, TN

    2009-10-13

    A system and method for high volume production of nanoparticles, nanotubes, and items incorporating nanoparticles and nanotubes. Microwave, radio frequency, or infrared energy vaporizes a metal catalyst which, as it condenses, is contacted by carbon or other elements such as silicon, germanium, or boron to form agglomerates. The agglomerates may be annealed to accelerate the production of nanotubes. Magnetic or electric fields may be used to align the nanotubes during their production. The nanotubes may be separated from the production byproducts in aligned or non-aligned configurations. The agglomerates may be formed directly into tools, optionally in compositions that incorporate other materials such as abrasives, binders, carbon-carbon composites, and cermets.

  12. A refined polarizable water model for the coarse-grained MARTINI force field with long-range electrostatic interactions

    NASA Astrophysics Data System (ADS)

    Michalowsky, Julian; Schäfer, Lars V.; Holm, Christian; Smiatek, Jens

    2017-02-01

    We present a refined version of the polarizable Martini water model - coined refPOL - designed specifically for the use with long-range electrostatics. The refPOL model improves the agreement with the experimentally measured dielectric constant and the mass density of water at room temperature compared to the original polarizable Martini water force field when particle mesh Ewald electrostatics are employed. Our study reveals that the model remains applicable with various commonly used settings for the non-bonded interactions, including reaction field electrostatics. The oil/water partitioning behavior of uncharged Martini bead types is thoroughly investigated: Lennard-Jones interactions between the refPOL model and the remaining Martini beads are adjusted to reproduce the hydration free energies obtained with the original polarizable water model, while free energies of solvation in apolar media remain unchanged. The cross-interactions with charged bead types are parameterized to agree with the experimentally observed area per lipid of a fully solvated dipalmitoylphosphatidylcholine bilayer. We additionally verify the model by analyzing the potentials of mean force between different sample pairs in refPOL water and comparing the results to reference data obtained using the original polarizable Martini water model as well as fully atomistic simulations. Based on the results, we suggest to replace the original polarizable Martini water model with the new refPOL model for future applications.

  13. Electrostatically screened, voltage-controlled electrostatic chuck

    DOEpatents

    Klebanoff, Leonard Elliott

    2001-01-01

    Employing an electrostatically screened, voltage-controlled electrostatic chuck particularly suited for holding wafers and masks in sub-atmospheric operations will significantly reduce the likelihood of contaminant deposition on the substrates. The electrostatic chuck includes (1) an insulator block having a outer perimeter and a planar surface adapted to support the substrate and comprising at least one electrode (typically a pair of electrodes that are embedded in the insulator block), (2) a source of voltage that is connected to the at least one electrode, (3) a support base to which the insulator block is attached, and (4) a primary electrostatic shield ring member that is positioned around the outer perimeter of the insulator block. The electrostatic chuck permits control of the voltage of the lithographic substrate; in addition, it provides electrostatic shielding of the stray electric fields issuing from the sides of the electrostatic chuck. The shielding effectively prevents electric fields from wrapping around to the upper or front surface of the substrate, thereby eliminating electrostatic particle deposition.

  14. Role of cold ionospheric plasma in the formation of a longitudinal electrostatic field on an auroral line of force

    NASA Astrophysics Data System (ADS)

    Kropotkin, A. P.

    1985-12-01

    A theoretical study shows that the appearance of a longitudinal electric field on auroral lines of force, connected with the existence of intense electron fluxes from the near-equatorial region and leading to the acceleration of auroral electrons, is complicated by the existence of a relatively dense ionospheric plasma hindering the penetration of the longitudinal field to low altitudes. A kinetic model is developed for such longitudinal electrostatic structures in auroral flux tubes. The model yields a consistent solution for the entire tube, obtained by matching solutions at its 'quasi-neutral' parts with a solution of double-layer type.

  15. Influence of inhomogeneities of the plasma density and electric field on the generation of electrostatic noise in the auroral zone

    SciTech Connect

    Chernyshov, A. A. Ilyasov, A. A. Mogilevskii, M. M.; Golovchanskaya, I. V. Kozelov, B. V.

    2015-03-15

    In order to study instabilities caused by inhomogeneities of the electric field and plasma density in the auroral zone, numerical algorithms are developed and numerical simulations are performed for different conditions in the background plasma. To this end, a nonlocal dispersion relation for a given type of wave is analyzed. It is shown that the dispersion relation has unstable solutions in a wide range of frequencies and wavenumbers. These solutions manifest themselves in satellite observations as a broadband spectrum of electrostatic perturbations. Two mechanisms of broadband noise generation related to the gradients of the density and electric field are compared.

  16. Compact electrostatic comb actuator

    DOEpatents

    Rodgers, M. Steven; Burg, Michael S.; Jensen, Brian D.; Miller, Samuel L.; Barnes, Stephen M.

    2000-01-01

    A compact electrostatic comb actuator is disclosed for microelectromechanical (MEM) applications. The actuator is based upon a plurality of meshed electrostatic combs, some of which are stationary and others of which are moveable. One or more restoring springs are fabricated within an outline of the electrostatic combs (i.e. superposed with the moveable electrostatic combs) to considerably reduce the space required for the actuator. Additionally, a truss structure is provided to support the moveable electrostatic combs and prevent bending or distortion of these combs due to unbalanced electrostatic forces or external loading. The truss structure formed about the moveable electrostatic combs allows the spacing between the interdigitated fingers of the combs to be reduced to about one micron or less, thereby substantially increasing the number of active fingers which can be provided in a given area. Finally, electrostatic shields can be used in the actuator to substantially reduce unwanted electrostatic fields to further improve performance of the device. As a result, the compact electrostatic comb actuator of the present invention occupies only a fraction of the space required for conventional electrostatic comb actuators, while providing a substantial increase in the available drive force (up to one-hundred times).

  17. High volume-high value usage of flue gas desulfurization (FGD) by-products in underground mines: Phase 2 -- Field investigations. Quarterly report, July 1--September 30, 1997

    SciTech Connect

    1997-12-31

    During this quarter, the majority of activity focused on grout emplacement at the Lodestar Energy Inc. (formerly Costain Coal Co.) surface mine auger holes described in the previous report. Specifically, two different types of grout pumps were investigated: a piston pump used in previous demonstrations, and a progressive cavity pump. The latter is currently utilized for grouting in underground coal mines, is relatively small and portable, and is capable of receiving dry material (e.g., fly ash) and water, mixing it to produce a grout, and pumping the grout at high pressure. It is therefore worthwhile to investigate it`s potential use in auger mine filling. Several field demonstrations were conducted using the different pumps. Numerous problems were encountered when using the progressive cavity pump, all of which were related to its inability to handle the highly reactive and heterogeneous FBC fly ash. Even relatively small ash agglomerates (<1 in. in diameter), which were not a problem for the larger piston pump, caused blockages in the progressive cavity pump which not only proved extremely difficult to clear, but also resulted in significant mechanical failures. Furthermore, mixing of dry fly ash with water within the progressive cavity pump was inconsistent and difficult to control. Consequently, the pump was unable to completely fill even a single auger hole. It was found that a large proportion of bed ash in the grout generated a large amount of heat and caused early stiffening of the material. During the experiments, cylinders of grout were prepared for compressive strength testing, and moisture contents were determined on-site. A thermocouple assembly was also constructed to record grout temperatures within an auger hole.

  18. Electrostatic solitary structures in presence of non-thermal electrons and a warm electron beam on the auroral field lines

    NASA Astrophysics Data System (ADS)

    Singh, S. V.; Lakhina, G. S.; Bharuthram, R.; Pillay, S. R.

    2011-12-01

    Electrostatic solitary waves (ESWs) have been observed by satellites in the auroral region of the Earth's magnetosphere. These ESWs are found to be having both positive and negative electrostatic potentials. Using the Sagdeeev psuedo-potential technique, arbitrary amplitude electron-acoustic solitary waves/double layers are studied in an unmagnetized plasma consisting of non-thermally distributed hot electrons, fluid cold electrons, a warm electron beam, and ions. The inertia of the warm electrons, and not the beam speed, is essential for the existence of positive potential solitary structures. Existence domains for positive as well as negative potential electrostatic solitons/double layers are obtained. For the typical auroral region parameters, the electric field amplitude of the negative potential solitons is found to be in the range ˜(3-30) mV/m and ˜(5-80) mV/m for the positive potential solitons. For the negative potential solitons/double layers, the amplitudes are higher when their widths are smaller. On the other hand, the amplitude of the positive potential structures increase with their widths.

  19. A self-consistent phase-field approach to implicit solvation of charged molecules with Poisson-Boltzmann electrostatics.

    PubMed

    Sun, Hui; Wen, Jiayi; Zhao, Yanxiang; Li, Bo; McCammon, J Andrew

    2015-12-28

    Dielectric boundary based implicit-solvent models provide efficient descriptions of coarse-grained effects, particularly the electrostatic effect, of aqueous solvent. Recent years have seen the initial success of a new such model, variational implicit-solvent model (VISM) [Dzubiella, Swanson, and McCammon Phys. Rev. Lett. 96, 087802 (2006) and J. Chem. Phys. 124, 084905 (2006)], in capturing multiple dry and wet hydration states, describing the subtle electrostatic effect in hydrophobic interactions, and providing qualitatively good estimates of solvation free energies. Here, we develop a phase-field VISM to the solvation of charged molecules in aqueous solvent to include more flexibility. In this approach, a stable equilibrium molecular system is described by a phase field that takes one constant value in the solute region and a different constant value in the solvent region, and smoothly changes its value on a thin transition layer representing a smeared solute-solvent interface or dielectric boundary. Such a phase field minimizes an effective solvation free-energy functional that consists of the solute-solvent interfacial energy, solute-solvent van der Waals interaction energy, and electrostatic free energy described by the Poisson-Boltzmann theory. We apply our model and methods to the solvation of single ions, two parallel plates, and protein complexes BphC and p53/MDM2 to demonstrate the capability and efficiency of our approach at different levels. With a diffuse dielectric boundary, our new approach can describe the dielectric asymmetry in the solute-solvent interfacial region. Our theory is developed based on rigorous mathematical studies and is also connected to the Lum-Chandler-Weeks theory (1999). We discuss these connections and possible extensions of our theory and methods.

  20. A self-consistent phase-field approach to implicit solvation of charged molecules with Poisson–Boltzmann electrostatics

    PubMed Central

    Sun, Hui; Wen, Jiayi; Zhao, Yanxiang; Li, Bo; McCammon, J. Andrew

    2015-01-01

    Dielectric boundary based implicit-solvent models provide efficient descriptions of coarse-grained effects, particularly the electrostatic effect, of aqueous solvent. Recent years have seen the initial success of a new such model, variational implicit-solvent model (VISM) [Dzubiella, Swanson, and McCammon Phys. Rev. Lett. 96, 087802 (2006) and J. Chem. Phys. 124, 084905 (2006)], in capturing multiple dry and wet hydration states, describing the subtle electrostatic effect in hydrophobic interactions, and providing qualitatively good estimates of solvation free energies. Here, we develop a phase-field VISM to the solvation of charged molecules in aqueous solvent to include more flexibility. In this approach, a stable equilibrium molecular system is described by a phase field that takes one constant value in the solute region and a different constant value in the solvent region, and smoothly changes its value on a thin transition layer representing a smeared solute-solvent interface or dielectric boundary. Such a phase field minimizes an effective solvation free-energy functional that consists of the solute-solvent interfacial energy, solute-solvent van der Waals interaction energy, and electrostatic free energy described by the Poisson–Boltzmann theory. We apply our model and methods to the solvation of single ions, two parallel plates, and protein complexes BphC and p53/MDM2 to demonstrate the capability and efficiency of our approach at different levels. With a diffuse dielectric boundary, our new approach can describe the dielectric asymmetry in the solute-solvent interfacial region. Our theory is developed based on rigorous mathematical studies and is also connected to the Lum–Chandler–Weeks theory (1999). We discuss these connections and possible extensions of our theory and methods. PMID:26723595

  1. Optimizing electrostatic field calculations with the adaptive Poisson-Boltzmann Solver to predict electric fields at protein-protein interfaces. I. Sampling and focusing.

    PubMed

    Ritchie, Andrew W; Webb, Lauren J

    2013-10-03

    Continuum electrostatics methods are commonly used to calculate electrostatic potentials in proteins and at protein-protein interfaces to aid many types of biophysical studies. Despite their ubiquity throughout the biophysical literature, these calculations are difficult to test against experimental data to determine their accuracy and validity. To address this, we have calculated the Boltzmann-weighted electrostatic field at the midpoint of a nitrile bond placed at a variety of locations on the surface of the protein RalGDS, both in its monomeric form as well as when docked to four different constructs of the protein Rap, and compared the computation results to vibrational absorption energy measurements of the nitrile oscillator. This was done by generating a statistical ensemble of protein structures using enhanced molecular dynamics sampling with the Amber03 force field, followed by solving the linear Poisson-Boltzmann equation for each structure using the Applied Poisson-Boltzmann Solver (APBS) software package. Using a two-stage focusing strategy, we examined numerous second stage box dimensions, grid point densities, box locations, and compared the numerical result to the result obtained from the sum of the numeric reaction field and the analytic Coulomb field. It was found that the reaction field method yielded higher correlation with experiment for the absolute calculation of fields, while the numeric solutions yielded higher correlation with experiment for the relative field calculations. Finer grid spacing typically improved the calculation, although this effect was less pronounced in the reaction field method. These sorts of calculations were also very sensitive to the box location, particularly for the numeric calculations of absolute fields using a 10(3) Å(3) box.

  2. Electrostatic instabilities and nonlinear structures associated with field-aligned plasma flows and Cairns-Tsallis electrons in the ionosphere

    NASA Astrophysics Data System (ADS)

    Shan, S. Ali; Saleem, H.

    2017-08-01

    Effects of non-Maxwellian electron densities on the low frequency electrostatic waves and instabilities are pointed out in a bi-ion plasma having field-aligned shear flow. Several different electron densities are used and formation of nonlinear stationary structures is investigated in different limits. Solutions of nonlinear equations are obtained in the form of KdV solitons and vortices and results are applied to terrestrial ionosphere. The deviation from Boltzmann density of the electrons enhances the linear shear flow-driven ion acoustic instability in the bi-ion plasma. But it plays destructive role in the formation of pulse type solitons.

  3. Linear (in oscillation dimensionless amplitude) interaction between the modes of a nonspherical charged drop in an external electrostatic field

    NASA Astrophysics Data System (ADS)

    Shiryaeva, S. O.; Petrushov, N. A.; Grigor'ev, A. I.

    2016-01-01

    The stability of a heavily charged drop in a weak uniform electrostatic field (in which the equilibrium shape of the drop can be represented by a prolate spheroid) is calculated in the fourth order of smallness in the eccentricity of the spheroidal drop and in the first order of smallness in the drop oscillation dimensionless amplitude. It is found that as the order of approximation in eccentricity grows, so does the number of modes interacting with the initially excited mode. In the given order of smallness, the preferred (initially excited) mode is shown to interact with the nearest eight modes. The drop becomes unstable if such is the second mode.

  4. Biological effects of the electrostatic field: red blood cell-related alterations of oxidative processes in blood

    NASA Astrophysics Data System (ADS)

    Harutyunyan, Hayk A.; Sahakyan, Gohar V.

    2016-01-01

    The aim of this study was to determine activities of pro-/antioxidant enzymes, reactive oxygen species (ROS) content, and oxidative modification of proteins and lipids in red blood cells (RBCs) and blood plasma of rats exposed to electrostatic field (200 kV/m) during the short (1 h) and the long periods (6 day, 6 h daily). Short-term exposure was characterized by the increase of oxidatively damaged proteins in blood of rats. This was strongly expressed in RBC membranes. After long-term action, RBC content in peripheral blood was higher than in control ( P < 0.01) and the attenuation of prooxidant processes was shown.

  5. Electrostatic self-force in the field of an (n + 1)-dimensional black hole: Dimensional regularization

    SciTech Connect

    Grats, Yu. V. Spirin, P. A.

    2016-01-15

    The self-energy of a classical charged particle localized at a relatively large distance outside the event horizon of an (n + 1)-dimensional Schwarzschild–Tangherlini black hole for an arbitrary n ≥ 3 is calculated. An expression for the electrostatic Green function is derived in the first two orders of the perturbation theory. Dimensional regularization is proposed to be used to regularize the corresponding formally divergent expression for the self-energy. The derived expression for the renormalized self-energy is compared with the results of other authors.

  6. Electrostatic Precipitator

    NASA Image and Video Library

    2017-06-09

    New Electrostatic Precipitator in a flow-through system. The precipitator system is being developed to remove dust from the atmospheric intakes of the MARS ISRU chambers. It uses electrostatic forces for the dust removal.

  7. Reduction of the electrostatic coupling in a large-area internal inductively coupled plasma source using a multicusp magnetic field

    NASA Astrophysics Data System (ADS)

    Lee, Y. J.; Kim, K. N.; Yeom, G. Y.; Lieberman, M. A.

    2004-09-01

    A large area (1020mm×830mm) inductively coupled plasma (ICP) source has been developed using an internal-type linear antenna with permanent magnets forming a multicusp magnetic field. The large rf antenna voltages, which cause the electrostatic coupling between the antenna and the plasma in a large area internal-type linear-antenna ICP source, were decreased significantly by applying the magnetic field near and parallel to the antenna. Through the application of the magnetic field, an approximately 20% higher plasma density, with a value of close to 1.0×1011cm-3 at a rf power of 2000W, and about three times higher photoresist etch rates were observed, while maintaining the plasma nonuniformity at less than 9%.

  8. Two-spacecraft charged particle observations interpreted in terms of electrostatic potential drops along polar cap field lines

    NASA Astrophysics Data System (ADS)

    Pollock, C. J.; Chappell, C. R.; Horwitz, J. L.; Winningham, J. D.

    We are studying the possible occurrence and magnitude of field-aligned electrostatic potential drops over the ionospheric polar caps. For this purpose, signatures in upgoing and downgoing photoelectrons, obtained in the topside ionosphere using the low altitude plasma instrument (LAPI) on the Dynamics Explorer 2 (DE 2), spacecraft are analyzed [Winningham and Gurgiolo, 1982]. These data are compared with positive ion data obtained at high altitude using the retarding ion mass spectrometer (RIMS) on the DE 1 spacecraft. Data were selected from intervals when DE 1 and DE 2 were approximately connected along polar cap magnetic field lines and when upflowing 0+ beams were observed in the RIMS data. We present here one case in which the comparison of data from the two DE spacecraft is quite favorable regarding its interpretation in terms of a field-aligned potential drop.

  9. The influence of external transverse magnetic field in propagation of electrostatic oscillations in single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Abdikian, Alireza

    2016-10-01

    Propagation of an electrostatic oscillation by using the linearized quantum hydrodynamic model in conjunction with Maxwell's equations was studied. The dispersion relation of a system of electron plasma in single-walled carbon nanotubes in the presence of an external magnetic field B 0 by considering the exchange-correlation effects in 2D cylindrical geometry is derived here. The uniform static magnetic field is assumed to be normal to the cylindrical surface (Voigt configuration). Distribution of the electrons and ions are considered uniformly over the cylindrical surface of a nanotube. It is found that the external magnetic field has significant impact on the wave in the longer wavelength. The influence of variation in azimuthal index and radius of the nanotube on dispersion relation is also discussed. It is tried to plot some schemes and analyze numerically in different limits of cylindrical and planar geometries. The results can be important in the study of collective phenomena in nanostructures.

  10. The Electrical Impact of Lightning Quasi-Electrostatic Fields on the Nighttime Lower Ionosphere: The Case of Negative Sprite Halos

    NASA Astrophysics Data System (ADS)

    Salem, M. A.; Liu, N.; Rassoul, H.

    2016-12-01

    It is well known that electrostatic (ES) and quasi-electrostatic (QE) fields can be established in the lower ionosphere by underlying thunderstorms. We recently found that although the thunderstorm ES field is not strong enough to produce transient luminous events (TLEs) such as halos and sprites, it generates significant effects on the electrical properties of the nighttime lower ionosphere [Salem et al., GRL., 42(6), doi: 10.1002/2015GL063268, 2015; Salem et al., GRL., 43(1), doi: 10.1002/2015GL066933, 2016]. In particular, according to Salem et al. [2016], the nighttime lower ionospheric height measured using the VLF wave reflection technique can be increased due to the effects of the ES field. In this work, we continue to study the nighttime lower ionospheric response to QE fields of cloud-to-ground (CG) lightning flashes. In contrast to thunderstorm ES fields, QE fields can be much stronger and trigger halos. Halos are relatively homogeneous glows centered on 75-85 km altitude, with a horizontal extent of tens of kilometers and a vertical thickness of several kilometers. They typically appear within a few milliseconds of their parent CGs. In particular, negative halos are caused by unusually impulsive negative CGs [Boggs et al., JGR. Atmos., doi: 10.1002/2015JD024188, 121(2), 2016; Liu et al., GRL., 43(6), doi: 10.1002/2016GL068256, 2016]. This study uses a one-dimensional plasma discharge fluid model combined with a simplified ionospheric ion chemistry model described by Liu [JGR., 117, doi: 10.1029/2011JA017062, 2012]. The response of the nighttime lower ionosphere to impulsive negative CGs is investigated for different ambient ionospheric density profiles and different CG properties (e.g., charge moment changes and charge transfer times). Finally, the modeling results of the lower ionosphere recovery time are analyzed to investigate the role of negative halos in producing different types of early VLF events.

  11. Electrostatic Fields Near the Active Site of Human Aldose Reductase: 2. New Inhibitors and Complications due to Hydrogen Bonds†

    PubMed Central

    Xu, Lin; Cohen, Aina E.; Boxer, Steven G.

    2011-01-01

    Vibrational Stark effect spectroscopy was used to measure electrostatic fields in the hydrophobic region of the active site of human aldose reductase (hALR2). A new nitrile-containing inhibitor was designed and synthesized, and the x-ray structure of its complex, along with cofactor NADP+, with wild-type hALR2 was determined at 1.3 Å resolution. The nitrile is found to be in close proximity to T113, consistent with a hydrogen bond interaction. Two vibrational absorption peaks were observed at room temperature in the nitrile region when the inhibitor binds to wild-type hALR2, indicating that the nitrile probe experiences two different microenvironments, and these could be empirically separated into a hydrogen bonded and non-hydrogen bonded population by comparison with the mutant T113A, where a hydrogen bond to the nitrile is not present. Classical molecular dynamics simulations based on the structure predict a double-peaked distribution in protein electric fields projected along the nitrile probe. The interpretation of these two peaks as a hydrogen bond formation-dissociation process between the probe nitrile group and a nearby amino acid side chain is used to explain the observation of two IR bands, and the simulations were used to investigate the molecular details of this conformational change. Hydrogen bonding complicates the simplest analysis of vibrational frequency shifts as being due solely to electrostatic interactions through the vibrational Stark effect, and the consequences of this complication are discussed. PMID:21859105

  12. Simple formulas for improved point-charge electrostatics in classical force fields and hybrid quantum mechanical/molecular mechanical embedding

    NASA Astrophysics Data System (ADS)

    Cisneros, G. A.; Tholander, S. Na-Im; Parisel, O.; Darden, T. A.; Elking, D.; Perera, L.; Piquemal, J.-P.

    We present a simple damping scheme for point-charge electrostatics that could be used directly in classical force fields. The approach acts at the charge (or monopole) level only and allows the inclusion of short-range electrostatic penetration effects at a very low cost. Results are compared with density functional theory Coulomb intermolecular interaction energies and with several other methods such as distributed multipoles, damped distributed multipoles, and transferable Hermite-Gaussian densities. Realistic trends in the interactions are observed for atom-centered Mertz-Kollman corrected point-charge distributions. The approach allows increasing the selectivity of parameters in the case of metal complexes. In addition, two QM/MM calculations are presented where the damping function is employed to include the MM atoms located at the QM/MM boundary. The first calculation corresponds to the gas-phase proton transfer of aspartic acid through water and the second is the first step of the reaction catalyzed by the 4-oxalocrotonate tautomerase (4OT) enzyme. First, improved agreement is observed when using the damping approach compared with the conventional excluded charge method or when including all charges in the calculation. Second, in the case of 4OT, the damped charge approach is in agreement with previous calculations, whereas including all charges gives a significantly higher energy barrier. In both cases, no reparameterization of the van der Waals part of the force field was performed.

  13. Self-consistent treatment of the local dielectric permittivity and electrostatic potential in solution for polarizable macromolecular force fields

    PubMed Central

    Hassan, Sergio A.

    2012-01-01

    A self-consistent method is presented for the calculation of the local dielectric permittivity and electrostatic potential generated by a solute of arbitrary shape and charge distribution in a polar and polarizable liquid. The structure and dynamics behavior of the liquid at the solute/liquid interface determine the spatial variations of the density and the dielectric response. Emphasis here is on the treatment of the interface. The method is an extension of conventional methods used in continuum protein electrostatics, and can be used to estimate changes in the static dielectric response of the liquid as it adapts to charge redistribution within the solute. This is most relevant in the context of polarizable force fields, during electron structure optimization in quantum chemical calculations, or upon charge transfer. The method is computationally efficient and well suited for code parallelization, and can be used for on-the-fly calculations of the local permittivity in dynamics simulations of systems with large and heterogeneous charge distributions, such as proteins, nucleic acids, and polyelectrolytes. Numerical calculation of the system free energy is discussed for the general case of a liquid with field-dependent dielectric response. PMID:22920098

  14. Trade-off between the electrostatic efficiency and mechanical stability of two-stage field emitter structures

    NASA Astrophysics Data System (ADS)

    de Assis, Thiago A.; Dall'Agnol, Fernando F.

    2017-01-01

    The electrostatic effects and mechanical stability of systems formed of nanostructures mounted on cylindrical/conical base structures were studied numerically using the finite element method. We modeled a base structure (lower-stage structure) with a height of h1, a base radius of r1, and a characteristic field enhancement factor (FEF) of γ1. The nanostructure on top (upper-stage structure) had a height of h2, a radius of r2 < r1, an FEF of γ2, and a hemisphere-on-post shape. The resulting two-stage system had a characteristic FEF of γC. We define the electrostatic efficiency as ηR=(γC-γ1)/(γ3-γ1) , where γ3 is the reference FEF for a hemisphere-on-post structure of radius r3 = r2 and height h3 = h1 + h2. The results suggest a scaling of ηR=f (u ≡λθ-n) , where λ≡h2/h1, θ≡r1/r2 , the exponent n depends on the geometry of the lower-stage structure, and u is a scale parameter of the two-stage system that arises from the scale-invariant nature of the electrostatic effects. Regarding the mechanical stability of the two-stage system, our results show that there are characteristic λ* and θ* values that result in the maximum mechanical stability. For a given relative difference δ between γC and γ3, our results suggest λ*θ*˜δα , where α ≈ 0.2 for both cylindrical and conical lower-stage structures. This result provides a relation between the electrostatic efficiency and the mechanical stability, allowing one to predict the necessary conditions for two-stage structures with the maximum sturdiness for a given FEF. This study, therefore, provides theoretical guidance for field electron emission applications, for the construction of needles for high-resolution probe microscopy, and for applications that require very high brightness but low emittance.

  15. Electronic responses of long chains to electrostatic fields: Hartree-Fock vs. density-functional theory: A model study

    SciTech Connect

    Vargas, Jorge; Springborg, Michael; Kirtman, Bernard

    2014-02-07

    The response to an electrostatic field is determined through simple model calculations, within both the restricted Hartree-Fock and density functional theory methods, for long, finite as well as infinite, periodic chains. The permanent dipole moment, μ{sub 0}, the polarizability, α, and the hyperpolarizabilities β and γ, calculated using a finite-field approach, are extensively analyzed. Our simple model allows for treatment of large systems and for separation of the properties into atomic and unit-cell contributions. That part of the response properties attributable to the terminations of the finite system change into delocalized current contributions in the corresponding infinite periodic system. Special emphasis is placed on analyzing the reasons behind the dramatic overestimation of the response properties found with density functional theory methods presently in common use.

  16. High volume data storage architecture analysis

    NASA Technical Reports Server (NTRS)

    Malik, James M.

    1990-01-01

    A High Volume Data Storage Architecture Analysis was conducted. The results, presented in this report, will be applied to problems of high volume data requirements such as those anticipated for the Space Station Control Center. High volume data storage systems at several different sites were analyzed for archive capacity, storage hierarchy and migration philosophy, and retrieval capabilities. Proposed architectures were solicited from the sites selected for in-depth analysis. Model architectures for a hypothetical data archiving system, for a high speed file server, and for high volume data storage are attached.

  17. Effect of thawing and cold storage on frozen chicken thigh meat quality by high-voltage electrostatic field.

    PubMed

    Hsieh, Chang-Wei; Lai, Cheng-Hung; Ho, Wai-Jane; Huang, Su-Chen; Ko, Wen-Ching

    2010-05-01

    One of the most popular issues in electrostatic biology is the effects of a high-voltage electrostatic field (HVEF) on the thawing of chicken thigh meat. In this study, chicken thigh meat was treated with HVEF (E-group), and compared to samples stored in a common refrigerator (R-group), to investigate how HVEF affects chicken thigh meat quality after thawing at low temperature storage (-3 and 4 degrees C). The results showed that there were no significant differences in biochemical and microorganism indices at -3 degrees C. However, the HVEF can significantly shorten thawing time for frozen chicken thigh meat at -3 degrees C. After thawing chicken thigh meat and storing at 4 degrees C, the total viable counts reached the Intl. Commission on Microbiological Specification for Foods limit of 10(7) CFU/g on the 6 and 8 d for the R- and E-group, respectively. On the 8th d, the volatile basic nitrogen had increased from 11.24 mg/100 g to 21.9 mg/100 g for the E-group and 39.9 mg/100 g for the R-group, respectively. The biochemical and microorganism indices also indicated that the E-group treatment yielded better results on thawing than the R-group treatment. The application of this model has the potential to keep products fresh.

  18. An investigation of flow-limited field-injection electrostatic spraying (FFESS) and its applications to thin film deposition

    NASA Astrophysics Data System (ADS)

    Singh, Ravindra Pratap

    Electrostatic spraying is the process of controlled disruption of a liquid surface due to excess surface charge density. The technique has found applications in a wide range of fields from agricultural sprays to fuel injectors to colloidal thrusters for space vehicle propulsion. Over the past 20 years, the technique has been intensely studied in material processing for synthesis of ceramic and metal powders, nanoparticles and thin films. The importance of the technique lies in its simple setup, high deposition efficiency, and ambient atmosphere operation. In conventional electrostatic spraying (CESS), one uses a conducting nozzle to charge the liquid, mostly by induction charging. CESS is therefore restricted to the single jet mode of spraying which occurs at low spray currents. It lacks stability and reproducibility in the high current, multiple jet regime, which can generate much finer sprays. In flow-limited field-injection electrostatic spraying (FFESS), one uses a field-injection electrode to stably and controllably inject higher currents into the liquid, a la Fowler-Nordheim, using an otherwise insulating nozzle. This way, it is possible to stably electrospray in the multiple jet mode. In addition to producing much finer sprays, the multi-jet mode atomizes liquids at higher rates, and spreads the spray over a wider region and more uniformly than single jet sprays, thus paving way for large-area uniform thin film deposition. A simple yet comprehensive theory is formulated to describe the multi jet formation. The theory, which is based on the energy minimization principle, takes into account, for the first time, the interactions between charged jets which leads to saturation in the number of jets at high spray currents. The possibility of using an array of nozzles to obtain uniform large-area high-throughput thin film deposition is also investigated. A large number of FFESS nozzles with alternating positive and negative polarities arranged in a periodic 2

  19. Avoidance of an electric field by insects: Fundamental biological phenomenon for an electrostatic pest-exclusion strategy

    NASA Astrophysics Data System (ADS)

    Matsuda, Y.; Nonomura, T.; Kakutani, K.; Kimbara, J.; Osamura, K.; Kusakari, S.; Toyoda, H.

    2015-10-01

    An electric field screen is a physical device used to exclude pest insects from greenhouses and warehouses to protect crop production and storage. The screen consists of iron insulated conductor wires (ICWs) arrayed in parallel and linked to each other, an electrostatic DC voltage generator used to supply a negative charge to the ICWs, and an earthed stainless net placed on one side of the ICW layer. The ICW was negatively charged to polarize the earthed net to create a positive charge on the ICW side surface, and an electric field formed between the opposite charges of the ICW and earthed net. The current study focused on the ability of the screen to repel insects reaching the screen net. This repulsion was a result of the insect's behaviour, i.e., the insects were deterred from entering the electric field of the screen. In fact, when the screen was negatively charged with the appropriate voltages, the insects placed their antennae inside the screen and then flew away without entering. Obviously, the insects recognized the electric field using their antennae and thereby avoided entering. Using a wide range of insects and spiders belonging to different taxonomic groups, we confirmed that the avoidance response to the electric field was common in these animals.

  20. A PI4P-driven electrostatic field controls cell membrane identity and signaling in plants

    PubMed Central

    Simon, Mathilde Laetitia Audrey; Platre, Matthieu Pierre; Marquès-Bueno, Maria Mar; Armengot, Laia; Stanislas, Thomas; Bayle, Vincent; Caillaud, Marie-Cécile; Jaillais, Yvon

    2016-01-01

    Many signaling proteins permanently or transiently localize to specific organelles for function. It is well established that certain lipids act as biochemical landmarks to specify compartment identity. However, they also influence membrane biophysical properties, which emerge as important features in specifying cellular territories. Such parameters include the membrane inner surface potential, which varies according to the lipid composition of each organelle. Here, we found that the plant plasma membrane (PM) and the cell plate of dividing cells have a unique electrostatic signature controlled by phosphatidylinositol-4-phosphate (PI4P). Our results further reveal that, contrarily to other eukaryotes, PI4P massively accumulates at the PM, establishing it as a critical hallmark of this membrane in plants. Membrane surface charges control the PM localization and function of the polar auxin transport regulator PINOID, as well as proteins from the BRI1 KINASE INHIBITOR1 (BKI1)/MEMBRANE ASSOCIATED KINASE REGULATORs (MAKRs) family, which are involved in brassinosteroid and receptor-like kinase signaling. We anticipate that this PI4P-driven physical membrane property will control the localization and function of many proteins involved in development, reproduction, immunity and nutrition. PMID:27322096

  1. Laser generated Ge ions accelerated by additional electrostatic field for implantation technology

    NASA Astrophysics Data System (ADS)

    Rosinski, M.; Gasior, P.; Fazio, E.; Ando, L.; Giuffrida, L.; Torrisi, L.; Parys, P.; Mezzasalma, A. M.; Wolowski, J.

    2013-05-01

    The paper presents research on the optimization of the laser ion implantation method with electrostatic acceleration/deflection including numerical simulations by the means of the Opera 3D code and experimental tests at the IPPLM, Warsaw. To introduce the ablation process an Nd:YAG laser system with repetition rate of 10 Hz, pulse duration of 3.5 ns and pulse energy of 0.5 J has been applied. Ion time of flight diagnostics has been used in situ to characterize concentration and energy distribution in the obtained ion streams while the postmortem analysis of the implanted samples was conducted by the means of XRD, FTIR and Raman Spectroscopy. In the paper the predictions of the Opera 3D code are compared with the results of the ion diagnostics in the real experiment. To give the whole picture of the method, the postmortem results of the XRD, FTIR and Raman characterization techniques are discussed. Experimental results show that it is possible to achieve the development of a micrometer-sized crystalline Ge phase and/or an amorphous one only after a thermal annealing treatment.

  2. Electrostatic precipitation

    SciTech Connect

    Albanese, V.

    1980-07-22

    A method is described of improving the conductivity of particles entrained in a stream of particle-laden gas formed by the burning of coal. The particles are collected by an electrostatic precipitator which comprises treating said gas containing particles prior to contact with the electrostatic precipitator at a temperature not greater than about 800/sup 0/F with a resistivitydecreasing amount of hexamethylene tetramine or its water-soluble salts and thereafter passing the gas to the electrostatic precipitator.

  3. Electrostatic end-field defocusing of neutral atoms and its compensation

    NASA Astrophysics Data System (ADS)

    Kalnins, Juris G.

    2011-10-01

    Neutral atoms entering an electric field experience a defocusing force in the dipole field direction, which is proportional to the field gradient. If an experiment, such as the search for a permanent electron electric dipole moment (eEDM), requires a very strong electric field (13.5MV/m), then this end-field defocusing results in beam blowup and much reduced phase-space acceptance. In this paper we discuss how these defocusing fields arise from the longitudinal changes in the electric dipole field and their dependence on the electrode shape and spacing between lenses. We find that the end-field defocusing comes from strong impulse forces, whose defocusing power was calculated for simple electrodes with rounded ends. To compensate for this end-field defocusing, a triplet of transverse-focusing lenses was added to the pure dipole field plates in the generic eEDM cesium fountain experiment used to study the neutral beam optics. Envelope equations, which calculated the beam sizes of the atom bunch for the linear forces, are used to obtain a set of lens parameters that give a well focused beam in the fountain. Atom trajectory equations allow us to calculate the phase-space acceptance of the lens system with the nonlinear force terms included.

  4. Interpreting the Coulomb-field approximation for generalized-Born electrostatics using boundary-integral equation theory.

    SciTech Connect

    Bardhan, J. P.; Mathematics and Computer Science

    2008-10-14

    The importance of molecular electrostatic interactions in aqueous solution has motivated extensive research into physical models and numerical methods for their estimation. The computational costs associated with simulations that include many explicit water molecules have driven the development of implicit-solvent models, with generalized-Born (GB) models among the most popular of these. In this paper, we analyze a boundary-integral equation interpretation for the Coulomb-field approximation (CFA), which plays a central role in most GB models. This interpretation offers new insights into the nature of the CFA, which traditionally has been assessed using only a single point charge in the solute. The boundary-integral interpretation of the CFA allows the use of multiple point charges, or even continuous charge distributions, leading naturally to methods that eliminate the interpolation inaccuracies associated with the Still equation. This approach, which we call boundary-integral-based electrostatic estimation by the CFA (BIBEE/CFA), is most accurate when the molecular charge distribution generates a smooth normal displacement field at the solute-solvent boundary, and CFA-based GB methods perform similarly. Conversely, both methods are least accurate for charge distributions that give rise to rapidly varying or highly localized normal displacement fields. Supporting this analysis are comparisons of the reaction-potential matrices calculated using GB methods and boundary-element-method (BEM) simulations. An approximation similar to BIBEE/CFA exhibits complementary behavior, with superior accuracy for charge distributions that generate rapidly varying normal fields and poorer accuracy for distributions that produce smooth fields. This approximation, BIBEE by preconditioning (BIBEE/P), essentially generates initial guesses for preconditioned Krylov-subspace iterative BEMs. Thus, iterative refinement of the BIBEE/P results recovers the BEM solution; excellent agreement

  5. Interpreting the Coulomb-field approximation for generalized-Born electrostatics using boundary-integral equation theory

    NASA Astrophysics Data System (ADS)

    Bardhan, Jaydeep P.

    2008-10-01

    The importance of molecular electrostatic interactions in aqueous solution has motivated extensive research into physical models and numerical methods for their estimation. The computational costs associated with simulations that include many explicit water molecules have driven the development of implicit-solvent models, with generalized-Born (GB) models among the most popular of these. In this paper, we analyze a boundary-integral equation interpretation for the Coulomb-field approximation (CFA), which plays a central role in most GB models. This interpretation offers new insights into the nature of the CFA, which traditionally has been assessed using only a single point charge in the solute. The boundary-integral interpretation of the CFA allows the use of multiple point charges, or even continuous charge distributions, leading naturally to methods that eliminate the interpolation inaccuracies associated with the Still equation. This approach, which we call boundary-integral-based electrostatic estimation by the CFA (BIBEE/CFA), is most accurate when the molecular charge distribution generates a smooth normal displacement field at the solute-solvent boundary, and CFA-based GB methods perform similarly. Conversely, both methods are least accurate for charge distributions that give rise to rapidly varying or highly localized normal displacement fields. Supporting this analysis are comparisons of the reaction-potential matrices calculated using GB methods and boundary-element-method (BEM) simulations. An approximation similar to BIBEE/CFA exhibits complementary behavior, with superior accuracy for charge distributions that generate rapidly varying normal fields and poorer accuracy for distributions that produce smooth fields. This approximation, BIBEE by preconditioning (BIBEE/P), essentially generates initial guesses for preconditioned Krylov-subspace iterative BEMs. Thus, iterative refinement of the BIBEE/P results recovers the BEM solution; excellent agreement

  6. Dual field effects in electrolyte-gated spinel ferrite: electrostatic carrier doping and redox reactions

    PubMed Central

    Ichimura, Takashi; Fujiwara, Kohei; Tanaka, Hidekazu

    2014-01-01

    Controlling the electronic properties of functional oxide materials via external electric fields has attracted increasing attention as a key technology for next-generation electronics. For transition-metal oxides with metallic carrier densities, the electric-field effect with ionic liquid electrolytes has been widely used because of the enormous carrier doping capabilities. The gate-induced redox reactions revealed by recent investigations have, however, highlighted the complex nature of the electric-field effect. Here, we use the gate-induced conductance modulation of spinel ZnxFe3−xO4 to demonstrate the dual contributions of volatile and non-volatile field effects arising from electronic carrier doping and redox reactions. These two contributions are found to change in opposite senses depending on the Zn content x; virtual electronic and chemical field effects are observed at appropriate Zn compositions. The tuning of field-effect characteristics via composition engineering should be extremely useful for fabricating high-performance oxide field-effect devices. PMID:25056718

  7. Field and material stresses predict observable surface forces in optical and electrostatic manipulation

    NASA Astrophysics Data System (ADS)

    Kemp, Brandon A.; Sheppard, Cheyenne J.

    2016-09-01

    The momentum of light in media has been one of the most debated topics in physics over the past one hundred years. Originally a theoretical debate over the electrodynamics of moving media, practical applications have emerged over the past few decades due to interest in optical manipulation and nanotechnology. Resolution of the debate identifies a kinetic momentum as the momentum of the fields responsible for center of mass translations and a canonical momentum related to the coupled field and material system. The optical momentum resolution has been considered incomplete because it did not uniquely identify the full stress-energy-momentum (SEM) tensor of the field-kinetic subsystem. A consequence of this partial resolution is that the field-kinetic momentum could be described by three of the leading formulations found in the literature. The Abraham, Einstein-Laub, and Chu SEM tensors share the field-kinetic momentum, but their SEM tensors differ resulting in competing force densities. We can show now that the Abraham and Einstein-Laub formulations are invalid since their SEM tensors are not frame invariant, whereas the Chu SEM tensor satisfies relativistic principles as the field-kinetic formulation. However, a number of reports indicate that the force distribution in matter may not accurately represent experimental observations. In this correspondence, we show that the field-kinetic SEM tensor can be used along with the corresponding material subsystem to accurately predict experimental force and stress distributions. We model experimental examples from optical and static manipulation of particles and fluids.

  8. Combined effect of constant high voltage electrostatic field and variable frequency pulsed electromagnetic field on the morphology of calcium carbonate scale in circulating cooling water systems.

    PubMed

    Zhao, Ju-Dong; Liu, Zhi-An; Zhao, Er-Jun

    2014-01-01

    Research on scale inhibition is of importance to improve the heat transfer efficiency of heat exchangers. The combined effect of high voltage electrostatic and variable frequency pulsed electromagnetic fields on calcium carbonate precipitation was investigated, both theoretically and experimentally. Using energy dispersive spectrum analysis, the predominant phase was found to be CaCO(3). The formed crystal phases mainly consist of calcite and aragonite, which is, in part, verified by theory. The results indicate that the setting of water flow velocity, and high voltage electrostatic and variable frequency pulsed electromagnetic fields is very important. Favorable values of these parameters can have a significant anti-scaling effect, with 68.95% of anti-scaling ratio for scale sample 13, while unfavorable values do not affect scale inhibition, but rather promoted fouling, such as scale sample 6. By using scanning electron microscopy analysis, when the anti-scaling ratio is positive, the particle size of scale was found to become smaller than that of untreated sample and the morphology became loose. The X-ray diffraction results verify that the good combined effect favors the appearance and growth of aragonite and restrains its transition to calcite. The mechanism for scale reduction is discussed.

  9. A multi-channel capacitive probe for electrostatic fluctuation measurement in the Madison Symmetric Torus reversed field pinch.

    PubMed

    Tan, Mingsheng; Stone, Douglas R; Triana, Joseph C; Almagri, Abdulgader F; Fiksel, Gennady; Ding, Weixing; Sarff, John S; McCollam, Karsten J; Li, Hong; Liu, Wandong

    2017-02-01

    A 40-channel capacitive probe has been developed to measure the electrostatic fluctuations associated with the tearing modes deep into Madison Symmetric Torus (MST) reversed field pinch plasma. The capacitive probe measures the ac component of the plasma potential via the voltage induced on stainless steel electrodes capacitively coupled with the plasma through a thin annular layer of boron nitride (BN) dielectric (also serves as the particle shield). When bombarded by the plasma electrons, BN provides a sufficiently large secondary electron emission for the induced voltage to be very close to the plasma potential. The probe consists of four stalks each with ten cylindrical capacitors that are radially separated by 1.5 cm. The four stalks are arranged on a 1.3 cm square grid so that at each radial position, there are four electrodes forming a square grid. Every two adjacent radial sets of four electrodes form a cube. The fluctuating electric field can be calculated by the gradient of the plasma potential fluctuations at the eight corners of the cube. The probe can be inserted up to 15 cm (r/a = 0.7) into the plasma. The capacitive probe has a frequency bandwidth from 13 Hz to 100 kHz, amplifier-circuit limit, sufficient for studying the tearing modes (5-30 kHz) in the MST reversed-field pinch.

  10. A multi-channel capacitive probe for electrostatic fluctuation measurement in the Madison Symmetric Torus reversed field pinch

    NASA Astrophysics Data System (ADS)

    Tan, Mingsheng; Stone, Douglas R.; Triana, Joseph C.; Almagri, Abdulgader F.; Fiksel, Gennady; Ding, Weixing; Sarff, John S.; McCollam, Karsten J.; Li, Hong; Liu, Wandong

    2017-02-01

    A 40-channel capacitive probe has been developed to measure the electrostatic fluctuations associated with the tearing modes deep into Madison Symmetric Torus (MST) reversed field pinch plasma. The capacitive probe measures the ac component of the plasma potential via the voltage induced on stainless steel electrodes capacitively coupled with the plasma through a thin annular layer of boron nitride (BN) dielectric (also serves as the particle shield). When bombarded by the plasma electrons, BN provides a sufficiently large secondary electron emission for the induced voltage to be very close to the plasma potential. The probe consists of four stalks each with ten cylindrical capacitors that are radially separated by 1.5 cm. The four stalks are arranged on a 1.3 cm square grid so that at each radial position, there are four electrodes forming a square grid. Every two adjacent radial sets of four electrodes form a cube. The fluctuating electric field can be calculated by the gradient of the plasma potential fluctuations at the eight corners of the cube. The probe can be inserted up to 15 cm (r/a = 0.7) into the plasma. The capacitive probe has a frequency bandwidth from 13 Hz to 100 kHz, amplifier-circuit limit, sufficient for studying the tearing modes (5-30 kHz) in the MST reversed-field pinch.

  11. Helical modulation of the electrostatic plasma potential due to edge magnetic islands induced by resonant magnetic perturbation fields at TEXTOR

    SciTech Connect

    Ciaccio, G. Spizzo, G.; Schmitz, O. Frerichs, H.; Abdullaev, S. S.; Evans, T. E.; White, R. B.

    2015-10-15

    The electrostatic response of the edge plasma to a magnetic island induced by resonant magnetic perturbations to the plasma edge of the circular limiter tokamak TEXTOR is analyzed. Measurements of plasma potential are interpreted by simulations with the Hamiltonian guiding center code ORBIT. We find a strong correlation between the magnetic field topology and the poloidal modulation of the measured plasma potential. The ion and electron drifts yield a predominantly electron driven radial diffusion when approaching the island X-point while ion diffusivities are generally an order of magnitude smaller. This causes a strong radial electric field structure pointing outward from the island O-point. The good agreement found between measured and modeled plasma potential connected to the enhanced radial particle diffusivities supports that a magnetic island in the edge of a tokamak plasma can act as convective cell. We show in detail that the particular, non-ambipolar drifts of electrons and ions in a 3D magnetic topology account for these effects. An analytical model for the plasma potential is implemented in the code ORBIT, and analyses of ion and electron radial diffusion show that both ion- and electron-dominated transport regimes can exist, which are known as ion and electron root solutions in stellarators. This finding and comparison with reversed field pinch studies and stellarator literature suggest that the role of magnetic islands as convective cells and hence as major radial particle transport drivers could be a generic mechanism in 3D plasma boundary layers.

  12. Electrostatically focused addressable field emission array chips (AFEA's) for high-speed massively parallel maskless digital E-beam direct write lithography and scanning electron microscopy

    DOEpatents

    Thomas, Clarence E.; Baylor, Larry R.; Voelkl, Edgar; Simpson, Michael L.; Paulus, Michael J.; Lowndes, Douglas H.; Whealton, John H.; Whitson, John C.; Wilgen, John B.

    2002-12-24

    Systems and methods are described for addressable field emission array (AFEA) chips. A method of operating an addressable field-emission array, includes: generating a plurality of electron beams from a pluralitly of emitters that compose the addressable field-emission array; and focusing at least one of the plurality of electron beams with an on-chip electrostatic focusing stack. The systems and methods provide advantages including the avoidance of space-charge blow-up.

  13. The effect of pulsating electrostatic field application on the development of delayed onset of muscle soreness (DOMS) symptoms after eccentric exercise

    PubMed Central

    Gatterer, Hannes; Peters, Philippe; Philippe, Marc; Burtscher, Martin

    2015-01-01

    [Purpose] The aim of the study was to establish whether pulsating electrostatic field application, shown to increase blood flow and metabolic activity and to function as an ion pump, is able to reduce muscle pain after exercise-induced muscle damage. [Subjects and Methods] Seven participants (4 males, 3 females) performed two sessions of downhill running separated by at least 4 weeks. After the running sessions, participants were either treated for 45 min with a pulsating electrostatic field (field intensity, 9000 V; current, <9 mA; frequency, 50 Hz) or a sham treatment. The order of the intervention was random, and the condition was blinded for the participants. Muscle soreness score, creatine kinase, and jump ability were assessed before and up to 48 hours after running. [Results] Twenty-four and 48 hours after the downhill running, the muscle soreness score tended to be less increased after pulsating electrostatic field administration when compared with the sham setting (changes in muscle soreness score: 3.7±1.6 vs. 5.7±2.2 after 24 h and 3.1±2.0 vs. 5.4±3.2 after 48 h, respectively). No further differences were detected. [Conclusion] The outcomes show that a pulsating electrostatic field might be a promising treatment to reduce muscle soreness after exercise-induced muscle damage. However, further studies are needed to confirm the present outcomes and to establish the mechanism by which a pulsating electrostatic field may reduce muscle pain. PMID:26644654

  14. The effect of pulsating electrostatic field application on the development of delayed onset of muscle soreness (DOMS) symptoms after eccentric exercise.

    PubMed

    Gatterer, Hannes; Peters, Philippe; Philippe, Marc; Burtscher, Martin

    2015-10-01

    [Purpose] The aim of the study was to establish whether pulsating electrostatic field application, shown to increase blood flow and metabolic activity and to function as an ion pump, is able to reduce muscle pain after exercise-induced muscle damage. [Subjects and Methods] Seven participants (4 males, 3 females) performed two sessions of downhill running separated by at least 4 weeks. After the running sessions, participants were either treated for 45 min with a pulsating electrostatic field (field intensity, 9000 V; current, <9 mA; frequency, 50 Hz) or a sham treatment. The order of the intervention was random, and the condition was blinded for the participants. Muscle soreness score, creatine kinase, and jump ability were assessed before and up to 48 hours after running. [Results] Twenty-four and 48 hours after the downhill running, the muscle soreness score tended to be less increased after pulsating electrostatic field administration when compared with the sham setting (changes in muscle soreness score: 3.7±1.6 vs. 5.7±2.2 after 24 h and 3.1±2.0 vs. 5.4±3.2 after 48 h, respectively). No further differences were detected. [Conclusion] The outcomes show that a pulsating electrostatic field might be a promising treatment to reduce muscle soreness after exercise-induced muscle damage. However, further studies are needed to confirm the present outcomes and to establish the mechanism by which a pulsating electrostatic field may reduce muscle pain.

  15. Transport of ions in presence of induced electric field and electrostatic turbulence - source of ions injected into ring current

    SciTech Connect

    Cladis, J.B.; Francis, W.E.

    1985-01-01

    The transport of ions from the polar ionosphere to the inner magnetosphere during stormtime conditions has been computed using a Monte Carlo diffusion code. The effect of the electrostatic turbulence assumed to be present during the substorm expansion phase was simulated by a process that accelerated the ions stochastically perpendicular to the magnetic field with a diffusion coefficient proportional to the energization rate of the ions by the induced electric field. This diffusion process was continued as the ions were convected from the plasma sheet boundary layer to the double-spiral injection boundary. Inward of the injection boundary, the ions were convected adiabatically. By using as input an O(+) flux of 2.8 x 10 to the 8th per sq cm per s (w greater than 10 eV) and an H(+) flux of 5.5 x 10 to the 8th per sq cm per s (w greater than 0.63 eV), the computed distribution functions of the ions in the ring current were found to be in good agreement, over a wide range in L (4 to 8), with measurements made with the ISEE-1 satellite during a storm. This O(+) flux and a large part of the H(+) flux are consistent with the DE satellite measurements of the polar ionospheric outflow during disturbed times. 19 references.

  16. Asymptotic boundary conditions with immersed finite elements for interface magnetostatic/electrostatic field problems with open boundary

    NASA Astrophysics Data System (ADS)

    Chu, Yuchuan; Cao, Yong; He, Xiaoming; Luo, Min

    2011-11-01

    Many of the magnetostatic/electrostatic field problems encountered in aerospace engineering, such as plasma sheath simulation and ion neutralization process in space, are not confined to finite domain and non-interface problems, but characterized as open boundary and interface problems. Asymptotic boundary conditions (ABC) and immersed finite elements (IFE) are relatively new tools to handle open boundaries and interface problems respectively. Compared with the traditional truncation approach, asymptotic boundary conditions need a much smaller domain to achieve the same accuracy. When regular finite element methods are applied to an interface problem, it is necessary to use a body-fitting mesh in order to obtain the optimal convergence rate. However, immersed finite elements possess the same optimal convergence rate on a Cartesian mesh, which is critical to many applications. This paper applies immersed finite element methods and asymptotic boundary conditions to solve an interface problem arising from electric field simulation in composite materials with open boundary. Numerical examples are provided to demonstrate the high global accuracy of the IFE method with ABC based on Cartesian meshes, especially around both interface and boundary. This algorithm uses a much smaller domain than the truncation approach in order to achieve the same accuracy.

  17. Transport of ions in presence of induced electric field and electrostatic turbulence - Source of ions injected into ring current

    NASA Technical Reports Server (NTRS)

    Cladis, J. B.; Francis, W. E.

    1985-01-01

    The transport of ions from the polar ionosphere to the inner magnetosphere during stormtime conditions has been computed using a Monte Carlo diffusion code. The effect of the electrostatic turbulence assumed to be present during the substorm expansion phase was simulated by a process that accelerated the ions stochastically perpendicular to the magnetic field with a diffusion coefficient proportional to the energization rate of the ions by the induced electric field. This diffusion process was continued as the ions were convected from the plasma sheet boundary layer to the double-spiral injection boundary. Inward of the injection boundary, the ions were convected adiabatically. By using as input an O(+) flux of 2.8 x 10 to the 8th per sq cm per s (w greater than 10 eV) and an H(+) flux of 5.5 x 10 to the 8th per sq cm per s (w greater than 0.63 eV), the computed distribution functions of the ions in the ring current were found to be in good agreement, over a wide range in L (4 to 8), with measurements made with the ISEE-1 satellite during a storm. This O(+) flux and a large part of the H(+) flux are consistent with the DE satellite measurements of the polar ionospheric outflow during disturbed times.

  18. Transport of ions in presence of induced electric field and electrostatic turbulence - Source of ions injected into ring current

    NASA Technical Reports Server (NTRS)

    Cladis, J. B.; Francis, W. E.

    1985-01-01

    The transport of ions from the polar ionosphere to the inner magnetosphere during stormtime conditions has been computed using a Monte Carlo diffusion code. The effect of the electrostatic turbulence assumed to be present during the substorm expansion phase was simulated by a process that accelerated the ions stochastically perpendicular to the magnetic field with a diffusion coefficient proportional to the energization rate of the ions by the induced electric field. This diffusion process was continued as the ions were convected from the plasma sheet boundary layer to the double-spiral injection boundary. Inward of the injection boundary, the ions were convected adiabatically. By using as input an O(+) flux of 2.8 x 10 to the 8th per sq cm per s (w greater than 10 eV) and an H(+) flux of 5.5 x 10 to the 8th per sq cm per s (w greater than 0.63 eV), the computed distribution functions of the ions in the ring current were found to be in good agreement, over a wide range in L (4 to 8), with measurements made with the ISEE-1 satellite during a storm. This O(+) flux and a large part of the H(+) flux are consistent with the DE satellite measurements of the polar ionospheric outflow during disturbed times.

  19. Electrostatic Kelvin-Helmholtz instability produced by a localized electric field perpendicular to an external magnetic field

    NASA Technical Reports Server (NTRS)

    Pritchett, P. L.

    1987-01-01

    The evolution of a plasma with a localized electric field perpendicular to an external magnetic field is shown to be dominated by the Kelvin-Helmholtz instability. For small ion gyroradius, the instability is similar to the fluid mode. When the ion gyroradius is an appreciable fraction of the spatial extent of the electric field, the plasma is not in equilibrium, and the initial drift profile relaxes. Subsequent evolution still leads to vortex flows.

  20. Use of axially symmetric electrostatic fields for ion-beam focussing

    SciTech Connect

    Colton, E.; Kelly, J.C.

    1983-01-01

    The 1/r electric field obtained between charged coaxial cylindrical electrodes is useful for focusing hollow ion beams in ion-microprobe and ion- implantation applications. The focusing strengths are mass-independent at nonrelativistic energies. Focused-particle densities can be enhanced by using a diverging-converging pair to flatten the dependence of focal length on incoming-beam radius. Transport of 425-keV and 1-MeV protons has been simulated and results are presented.

  1. Improvement of the Planetary Gravitational Potentiel Field Knwoledge with Accurate Electrostatic Accelerometer / Gradiometer

    NASA Astrophysics Data System (ADS)

    Christophe, B.; Lebat, V.; Foulon, B.; Liorzou, F.; Perrot, E.; Boulanger, D.; Hardy, E.

    2014-12-01

    ONERA has developed since several years the most accurate accelerometers for the geodesy mission. The accelerometers are still operational in the GRACE mission. Their successors for the GRACE-FO mission are under manufacturing and will fly in 2017. Finally, the GOCE mission has proved the interest of gradiometer for a direct measurement of the gravity field.Now, ONERA proposes a new design of accelerometer, MicroSTAR, for interplanetary mission. It inherits of the same technology but with reduced mass and consumption. It has been proposed in several missions towards outer planets in order to test the deviation to the relativity general over large distance to the sun (with the addition of a bias rejection system). But the same instrument could be interesting to improve our knowledge of the planetary gravitational potential field, allowing a better understanding of the planet interior composition. The success of using accelerometer for geodesy mission could be imported in the planetary science.The paper will present the accuracy achievable on the gravity potential field according to different accelerometer configurations (one accelerometer, one gradiometer arm or a complete 3-axis gradiometer). Then, the instrument will be described and the integration of the instrument inside an interplanetary probe will be evoked.

  2. An image-based reaction field method for electrostatic interactions in molecular dynamics simulations of aqueous solutions

    NASA Astrophysics Data System (ADS)

    Lin, Yuchun; Baumketner, Andrij; Deng, Shaozhong; Xu, Zhenli; Jacobs, Donald; Cai, Wei

    2009-10-01

    In this paper, a new solvation model is proposed for simulations of biomolecules in aqueous solutions that combines the strengths of explicit and implicit solvent representations. Solute molecules are placed in a spherical cavity filled with explicit water, thus providing microscopic detail where it is most needed. Solvent outside of the cavity is modeled as a dielectric continuum whose effect on the solute is treated through the reaction field corrections. With this explicit/implicit model, the electrostatic potential represents a solute molecule in an infinite bath of solvent, thus avoiding unphysical interactions between periodic images of the solute commonly used in the lattice-sum explicit solvent simulations. For improved computational efficiency, our model employs an accurate and efficient multiple-image charge method to compute reaction fields together with the fast multipole method for the direct Coulomb interactions. To minimize the surface effects, periodic boundary conditions are employed for nonelectrostatic interactions. The proposed model is applied to study liquid water. The effect of model parameters, which include the size of the cavity, the number of image charges used to compute reaction field, and the thickness of the buffer layer, is investigated in comparison with the particle-mesh Ewald simulations as a reference. An optimal set of parameters is obtained that allows for a faithful representation of many structural, dielectric, and dynamic properties of the simulated water, while maintaining manageable computational cost. With controlled and adjustable accuracy of the multiple-image charge representation of the reaction field, it is concluded that the employed model achieves convergence with only one image charge in the case of pure water. Future applications to pKa calculations, conformational sampling of solvated biomolecules and electrolyte solutions are briefly discussed.

  3. Role of electrostatic and magnetic electron confinement in a hollow-cathode glow discharge in a nonuniform magnetic field

    SciTech Connect

    Metel, A. S. Grigoriev, S. N.; Volosova, M. A.; Bolbukov, V. P.; Melnik, Yu. A.

    2015-02-15

    Glow discharge with electron confinement in an electrostatic trap has been studied. The trap is formed by a cylindrical hollow cathode, as well as by a flat target on its bottom and a grid covering its output aperture, both being negatively biased relative to the cathode. At a gas pressure of 0.2–0.4 Pa, the fraction of ions sputtering the target (δ = 0.13) in the entire number of ions emitted by the uniform discharge plasma corresponds to the ratio of the target surface area to the total surface area of the cathode, grid, and target. When a nonuniform magnetic field with force lines passing through the target center (where the magnetic induction reaches 35 mT), as well as through the grid, hollow cathode, and target periphery (where the field lines are arc-shaped), is applied to the trap, its influence on the discharge depends on the magnetic induction B{sub 0} at the target edge. At B{sub 0} = 1 mT, the electrons emitted from the target periphery and drifting azimuthally in the arc-shaped field insignificantly contribute to gas ionization. Nevertheless, since fast electrons that are emitted from the cathode and oscillate inside it are forced by the magnetic field to come more frequently to the target, thereby intensifying gas ionization near the latter, the fraction δ doubles and the plasma density near the target becomes more than twice as high as that near the grid. At B{sub 0} = 6 mT, the contribution of electrons emitted from the target surface to gas ionization near the target grows up and δ increases two more times. At cathode-target voltages in the range of 0–3 kV, the current in the target circuit vanishes as the voltage between the anode and the cathode decreases to zero.

  4. Electrostatic ion-cyclotron instability caused by a nonuniform electric field perpendicular to the external magnetic field

    NASA Technical Reports Server (NTRS)

    Ganguli, G.; Lee, Y. C.; Palmadesso, P.

    1985-01-01

    A new mechanism that can destablize kinetic ion-cyclotron waves in the presence of a nonuniform electric field perpendicular to the uniform ambient magnetic field is given. In the absence of the electric field, the mode energy is positive, while in the presence of a uniform electric field the mode energy could be negative. However, when the electric field is nonuniform, it is possible for a finite region to be of negative wave energy surrounded by regions of positive wave energy. A nonlocal wave packet couples the two regions so that a flow of energy from the region of negative wave energy to the region of positive wave energy will cause the mode to grow. This gives rise to the instability.

  5. Radiation of electromagnetic waves by a dipole in an external uniform electrostatic field

    NASA Astrophysics Data System (ADS)

    Manaenkov, S. I.

    2017-01-01

    Exact solution for the electromagnetic field densities E and H of a dipole of uniformly accelerated point-charges with identical masses is discussed. It is shown that, for any fixed time t and a large distance R between the center of the dipole and the fieldpoint, | E| R -4, | H| R -5, while for large c| t| R, | E| | H| 1/ R as in spherical electromagnetic waves. Nevertheless, any irreversible radiation of electromagnetic waves is absent since the wave zone does not exist.

  6. Lightning-Driven Electric Fields in the Stratosphere: Comparisons Between In-Situ Measurements and a Quasi-Electrostatic Field Model

    NASA Astrophysics Data System (ADS)

    Thomas, J. N.; Holzworth, R. H.; McCarthy, M. P.; Roy, N. G.; Solorzano, N. N.; Pinto, O.; Sato, M.

    2004-12-01

    During the Sprite Balloon Campaign in southeastern Brazil (December 6-7, 2002), 38 electric field changes greater than 10~V/m, correlated with cloud-to-ground and intra-cloud lightning, were measured above 30~km in altitude in the stratosphere. These electric field signatures are compared directly to an axi-symmetric quasi-electrostatic field (QSF) model developed by the authors and based on the model of Pasko et al. '97. Both the amplitude and the relaxation time of the lightning-driven electric fields are compared to this QSF model at the exact location of the in-situ balloon-borne measurements. The Brazilian Integrated Network (BIN), a regional ground-based lightning detection network that covers the southeast of Brazil, provides lightning location and peak current values for cloud-to-ground strokes, while remote extremely low frequency (ELF) magnetic field measurements from Japan and Antarctica provide charge moment estimates. These network and remote measurements, along with in-situ measurements of the conductivity by the Sprite flight 1 balloon payload, provide realistic input parameters to this QSF model. The in-situ electric field measurements are compared to the output of the QSF model for various cloud charge distributions and atmospheric conductivity profiles. When the electric field measurements agree well with the QSF model, the model can predict the electric field signature everywhere in the stratosphere and mesosphere, including sprite initiation altitudes. Thus, by utilizing in-situ electric field and conductivity measurements, local lightning network data, remote ELF measurements, and a QSF model of the lightning discharge, we are able to predict the amplitude and relaxation time of the electric field at sprite altitudes.

  7. Electrostatics of proteins in dielectric solvent continua. II. Hamiltonian reaction field dynamics

    NASA Astrophysics Data System (ADS)

    Bauer, Sebastian; Tavan, Paul; Mathias, Gerald

    2014-03-01

    In Paper I of this work [S. Bauer, G. Mathias, and P. Tavan, J. Chem. Phys. 140, 104102 (2014)] we have presented a reaction field (RF) method, which accurately solves the Poisson equation for proteins embedded in dielectric solvent continua at a computational effort comparable to that of polarizable molecular mechanics (MM) force fields. Building upon these results, here we suggest a method for linearly scaling Hamiltonian RF/MM molecular dynamics (MD) simulations, which we call "Hamiltonian dielectric solvent" (HADES). First, we derive analytical expressions for the RF forces acting on the solute atoms. These forces properly account for all those conditions, which have to be self-consistently fulfilled by RF quantities introduced in Paper I. Next we provide details on the implementation, i.e., we show how our RF approach is combined with a fast multipole method and how the self-consistency iterations are accelerated by the use of the so-called direct inversion in the iterative subspace. Finally we demonstrate that the method and its implementation enable Hamiltonian, i.e., energy and momentum conserving HADES-MD, and compare in a sample application on Ac-Ala-NHMe the HADES-MD free energy landscape at 300 K with that obtained in Paper I by scanning of configurations and with one obtained from an explicit solvent simulation.

  8. Electrostatic particle-in-cell simulation of heat flux mitigation using magnetic fields

    NASA Astrophysics Data System (ADS)

    Lüskow, Karl Felix; Kemnitz, S.; Bandelow, G.; Duras, J.; Kahnfeld, D.; Matthias, P.; Schneider, R.; Konigorski, D.

    2016-10-01

    The particle-in-cell (PIC) method was used to simulate heat flux mitigation experiments with partially ionised argon. The experiments demonstrate the possibility of reducing heat flux towards a target using magnetic fields. Modelling using the PIC method is able to reproduce the heat flux mitigation qualitatively. This is driven by modified electron transport. Electrons are magnetised and react directly to the external magnetic field. In addition, an increase of radial turbulent transport is also needed to explain the experimental observations in the model. Close to the target an increase of electron density is created. Due to quasi-neutrality, ions follow the electrons. Charge exchange collisions couple the dynamics of the neutrals to the ions and reduce the flow velocity of neutrals by radial momentum transport and subsequent losses. By this, the dominant heat-transport channel by neutrals gets reduced and a reduction of the heat deposition, similar to the experiment, is observed. Using the simulation a diagnostic module for optical emission is developed and its results are compared with spectroscopic measurements and photos from the experiment. The results of this study are in good agreement with the experiment. Experimental observations such as a shrank bright emission region close to the nozzle exit, an additional emission in front of the target and an overall change in colour to red are reproduced by the simulation.

  9. Top hat electrostatic analyzer for far-field electric propulsion plume diagnostics

    SciTech Connect

    Victor, Allen L.; Zurbuchen, Thomas H.; Gallimore, Alec D.

    2006-01-15

    The design, development, and testing of the top hat electric propulsion plume analyzer (TOPAZ) are presented for far-field electric propulsion plume diagnostics. The trend towards high-power thruster development will require plume diagnostic techniques capable of measuring high-energy particles as well as low-energy ions produced from charge-exchange collisions due to elevated facility background pressures. TOPAZ incorporates a 'top hat' design with a geometrical analyzer constant of 100 resulting in a wide energy range and a high-energy resolution. SIMION, an ion trajectory analysis program, was used to predict characteristics of the analyzer. An ion beam accelerator system confirms the computational results. TOPAZ provides an energy resolution of 2.7%, field of view of 112 deg. x 26 deg. (azimuthal by elevation) with an angular resolution in each direction of 2 deg., and a demonstrated energy-per-charge acceptance range of 5-15 keV. An energy profile measurement of the NASA-173Mv1 Hall thruster demonstrates instrument operation in a Hall thruster plume.

  10. Electrostatics of proteins in dielectric solvent continua. II. Hamiltonian reaction field dynamics

    SciTech Connect

    Bauer, Sebastian; Tavan, Paul; Mathias, Gerald

    2014-03-14

    In Paper I of this work [S. Bauer, G. Mathias, and P. Tavan, J. Chem. Phys. 140, 104102 (2014)] we have presented a reaction field (RF) method, which accurately solves the Poisson equation for proteins embedded in dielectric solvent continua at a computational effort comparable to that of polarizable molecular mechanics (MM) force fields. Building upon these results, here we suggest a method for linearly scaling Hamiltonian RF/MM molecular dynamics (MD) simulations, which we call “Hamiltonian dielectric solvent” (HADES). First, we derive analytical expressions for the RF forces acting on the solute atoms. These forces properly account for all those conditions, which have to be self-consistently fulfilled by RF quantities introduced in Paper I. Next we provide details on the implementation, i.e., we show how our RF approach is combined with a fast multipole method and how the self-consistency iterations are accelerated by the use of the so-called direct inversion in the iterative subspace. Finally we demonstrate that the method and its implementation enable Hamiltonian, i.e., energy and momentum conserving HADES-MD, and compare in a sample application on Ac-Ala-NHMe the HADES-MD free energy landscape at 300 K with that obtained in Paper I by scanning of configurations and with one obtained from an explicit solvent simulation.

  11. Electrostatics of proteins in dielectric solvent continua. II. Hamiltonian reaction field dynamics.

    PubMed

    Bauer, Sebastian; Tavan, Paul; Mathias, Gerald

    2014-03-14

    In Paper I of this work [S. Bauer, G. Mathias, and P. Tavan, J. Chem. Phys. 140, 104102 (2014)] we have presented a reaction field (RF) method, which accurately solves the Poisson equation for proteins embedded in dielectric solvent continua at a computational effort comparable to that of polarizable molecular mechanics (MM) force fields. Building upon these results, here we suggest a method for linearly scaling Hamiltonian RF/MM molecular dynamics (MD) simulations, which we call "Hamiltonian dielectric solvent" (HADES). First, we derive analytical expressions for the RF forces acting on the solute atoms. These forces properly account for all those conditions, which have to be self-consistently fulfilled by RF quantities introduced in Paper I. Next we provide details on the implementation, i.e., we show how our RF approach is combined with a fast multipole method and how the self-consistency iterations are accelerated by the use of the so-called direct inversion in the iterative subspace. Finally we demonstrate that the method and its implementation enable Hamiltonian, i.e., energy and momentum conserving HADES-MD, and compare in a sample application on Ac-Ala-NHMe the HADES-MD free energy landscape at 300 K with that obtained in Paper I by scanning of configurations and with one obtained from an explicit solvent simulation.

  12. Second harmonic generation in carbon nanotubes induced by transversal electrostatic field.

    PubMed

    Trolle, Mads Lund; Pedersen, Thomas Garm

    2013-08-14

    Carbon nanotubes (CNTs) of armchair and zigzag type contain an inversion centre, and are thus intrinsically unable to generate dipole even-order nonlinearities, such as second harmonic generation (SHG). Breaking the inversion symmetry by application of an external voltage transversal to the CNT axis will, however, induce a second harmonic response. Similarly, additional non-vanishing second harmonic tensor elements will be induced in chiral tubes already displaying an intrinsic response. Many geometries realizing such a setup can be envisaged, e.g., an experimental gate setup or deposition of CNTs on, or integration in, strongly polarized host media, perhaps facilitating a tunable second harmonic response. In this work, we calculate the SHG signal from CNTs under transversally applied electric fields based on a tight-binding model.

  13. HEATING OF SIMPLE SOLUTIONS AND EMULSIONS EXPOSED TO HIGH FREQUENCY HIGH POTENTIAL ELECTROSTATIC FIELDS

    PubMed Central

    Marshall, W. H.

    1930-01-01

    1. It is shown that the absorption in liquid dielectrics is a function of potential gradient (field intensity) as well as frequency and that for values of potential gradient above, at least 70 volts per millimeter, the rate of rise of temperature-frequency curve increases rapidly with frequency. 2. The presence of ions in measurable quantity considerably changes the absorption characteristics and apparently causes the values to remain constant, whereas the values for water drop about 40 per cent, during exposure. The absorption also changes rapidly with the concentration of the electrolyte. 3. Very high absorption values are found for an emulsion of cotton-seed oil in 1 per cent sodium oleate. It is shown that the absorption is due to the colloidal structure (with the possibility that the energy is dissipated at the phase boundaries). PMID:19872553

  14. Electrostatic analyzer with a 3-D instantaneous field of view for fast measurements of plasma distribution functions in space

    NASA Astrophysics Data System (ADS)

    Morel, X.; Berthomier, M.; Berthelier, J.-J.

    2017-03-01

    We describe the concept and properties of a new electrostatic optic which aims to provide a 2π sr instantaneous field of view to characterize space plasmas. It consists of a set of concentric toroidal electrodes that form a number of independent energy-selective channels. Charged particles are deflected toward a common imaging planar detector. The full 3-D distribution function of charged particles is obtained through a single energy sweep. Angle and energy resolution of the optics depends on the number of toroidal electrodes, on their radii of curvature, on their spacing, and on the angular aperture of the channels. We present the performances, as derived from numerical simulations, of an initial implementation of this concept that would fit the need of many space plasma physics applications. The proposed instrument has 192 entrance windows corresponding to eight polar channels each with 24 azimuthal sectors. The initial version of this 3-D plasma analyzer may cover energies from a few eV up to 30 keV, typically with a channel-dependent energy resolution varying from 10% to 7%. The angular acceptance varies with the direction of the incident particle from 3° to 12°. With a total geometric factor of two sensor heads reaching 0.23 cm2 sr eV/eV, this "donut" shape analyzer has enough sensitivity to allow very fast measurements of plasma distribution functions in most terrestrial and planetary environments on three-axis stabilized as well as on spinning satellites.

  15. Increasing the efficiency of organic solar cells by photonic and electrostatic-field enhancements

    SciTech Connect

    Nalwa, Kanwar

    2011-01-01

    recombination of charge carriers. Thus it becomes imperative to understand the effect of processing conditions such as spin coating speed and drying rate on defect density and hence induced carrier recombination mechanism. In this study, It is shown that slow growth (longer drying time) of the active-layer leads to reduction of sub-bandgap traps by an order of magnitude as compared to fast grown active-layer. By coupling the experimental results with simulations, it is demonstrated that at one sun condition, slow grown device has bimolecular recombination as the major loss mechanism while in the fast grown device with high trap density, the trap assisted recombination dominates. It has been estimated that non-radiative recombination accounts nearly 50% of efficiency loss in modern OPVs. Generally, an external bias (electric field) is required to collect all the photogenerated charges and thus prevent their recombination. The motivation is to induce additional electric field in otherwise low mobility conjugated polymer based active layer by incorporating ferroelectric dipoles. This is expected to facilitate singlet exciton dissociation in polymer matrix and impede charge transfer exciton (CTE) recombination at polymer:fullerene interface. For the first time, it is shown that the addition of ferroelectric dipoles to modern bulk heterojunction (BHJ) can significantly improve exciton dissociation, resulting in a ~50% enhancement of overall solar cell efficiency. The devices also exhibit the unique ferroelectric-photovoltaic effect with polarization-controlled power conversion efficiency.

  16. Electrostatic Precipitator

    NASA Image and Video Library

    2017-06-09

    Dr. Carlos Calle, lead scientist in the Kennedy Space Center's Electrostatics and Surface Physics Laboratory, left, and Jay Phillips, a research physicist, are modifying an electrostatic precipitator to help remove dust from simulated Martian atmosphere. NASA's Journey to Mars requires cutting-edge technologies to solve the problems explorers will face on the Red Planet. Scientists are developing some of the needed solutions by adapting a device to remove the ever-present dust from valuable elements in the Martian atmosphere. Those commodities include oxygen, water and methane.

  17. Electrostatic Precipitator

    NASA Image and Video Library

    2017-06-09

    Dr. Carlos Calle, lead scientist in the Kennedy Space Center's Electrostatics and Surface Physics Laboratory, left, and Jay Phillips, a research physicist, are modifying an electrostatic precipitator to help remove dust from a simulated Martian atmosphere. NASA's Journey to Mars requires cutting-edge technologies to solve the problems explorers will face on the Red Planet. Scientists are developing some of the needed solutions by adapting a device to remove the ever-present dust from valuable elements in the Martian atmosphere. Those commodities include oxygen, water and methane.

  18. Electrostatic Precipitator

    NASA Image and Video Library

    2017-06-09

    In their Swamp Works laboratory at NASA's Kennedy Space Center, Dr. Carlos Calle and Jay Phillips are testing an electrostatic precipitator using dust that closely approximates the make-up of that on Mars. They upgraded their electrostatic precipitator to fully simulate Martian atmosphere by designing and constructing a dust aerosolization pre-chamber. The agency's Journey to Mars requires cutting-edge technologies to solve the problems explorers will face on the Red Planet. Scientists are developing some of the needed solutions by adapting a device to remove the ever-present dust from valuable elements in the Martian atmosphere. Those commodities include oxygen, water and methane.

  19. Electrostatic Precipitator

    NASA Image and Video Library

    2017-06-09

    Jay Phillips, a research physicist in the Kennedy Space Center's Electrostatics and Surface Physics Laboratory, left, and Dr. Carlos Calle, lead scientist in the lab, are modifying an electrostatic precipitator to help remove dust from simulated Martian atmosphere. NASA's Journey to Mars requires cutting-edge technologies to solve the problems explorers will face on the Red Planet. Scientists are developing some of the needed solutions by adapting a device to remove the ever-present dust from valuable elements in the Martian atmosphere. Those commodities include oxygen, water and methane.

  20. A novel easy-driving and easy-signal-processing electrostatic field sensor based on a piezoresistance and polyethylene terephthalate lever

    NASA Astrophysics Data System (ADS)

    Bai, Minyu; Zhao, Yulong; Jiao, Binbin; Zhai, Xiaoshe; Geng, Yingsan

    2017-03-01

    A novel electrostatic field sensor with compact structure and a simple signal processing circuit is proposed in this paper. The sensor is based on a piezoresistive force meter and a lathy polyethylene terephthalate (PET) lever for electrostatic force generation and transformation. The force meter with a rectangular membrane supported by four beams was fabricated and one end of the PET lever was attached to the center of the membrane surface. The other end of the lever was free for electrostatic force generation. Only a low voltage DC source was required for the whole sensor, rather than sophisticated driving circuits. The lever magnified the electrostatic force effecting upon the force meter, and thus the output of the sensor was large enough for a simple processing circuit to be sufficient, rather than requiring complicated instruments. Characteristics of the sensor formation make it appropriate to adopt this sensor in various applications, in particular in high voltage power systems monitoring and meteorology measurements. The experiment results showed agreement with simulation results of the sensor. Sensitivity of the prototype of this sensor was 0.06  √mV (kV · m-1)-1 which can be greatly promoted by design optimization and fabrication improvement.

  1. Low-temperature adsorption/storage of hydrogen on FAU, MFI, and MOR zeolites with various Si/Al ratios: effect of electrostatic fields and pore structures.

    PubMed

    Jhung, Sung Hwa; Yoon, Ji Woong; Lee, Ji Sun; Chang, Jong-San

    2007-01-01

    Several zeolites, such as faujasite, mordenite, and ZSM-5, with various aluminum contents have been used to analyze the effect of aluminum or cation concentration (strength of electrostatic field) on hydrogen adsorption at low temperature. Irrespective of the zeolite structure, the adsorption capacity, isosteric heat of adsorption (-DeltaHads), surface coverage, and micropore occupancy increase with increasing aluminum content of a zeolite. Zeolites with a higher amount of aluminum favorably adsorb hydrogen at relatively low pressures. For zeolites with similar aluminum contents, the adsorption capacity, isosteric heat of adsorption, surface coverage, and micropore occupancy are in the order of mordenite>ZSM-5>faujasite, probably due to differing pore sizes and the presence or absence of pore intersections. This work demonstrates that zeolites with strong electrostatic fields and narrow pores without intersections are beneficial for high hydrogen uptake.

  2. Electrostatic Toys.

    ERIC Educational Resources Information Center

    Greenslade, Thomas B., Jr.

    1982-01-01

    Describes typical electrostatic toys which may be used to show students phenomena associated with sparks, sudden drops in potential, induction, and forces between bodies of like and opposite charges. Many of these demonstrations are suitable for student projects. (Author/JN)

  3. Teaching Electrostatics in University Courses

    ERIC Educational Resources Information Center

    Hughes, J. F.

    1974-01-01

    Describes an optional course on applied electrostatics that was offered to electrical engineers in their final year. Topics included the determination of electric fields, nature of the charging process, static electricity in liquids, solid state processes, charged particle applications, and electrostatic ignition. (GS)

  4. Teaching Electrostatics in University Courses

    ERIC Educational Resources Information Center

    Hughes, J. F.

    1974-01-01

    Describes an optional course on applied electrostatics that was offered to electrical engineers in their final year. Topics included the determination of electric fields, nature of the charging process, static electricity in liquids, solid state processes, charged particle applications, and electrostatic ignition. (GS)

  5. Modeling the response of a top hat electrostatic analyzer in an external magnetic field: Experimental validation with the Juno JADE-E sensor

    NASA Astrophysics Data System (ADS)

    Clark, G.; Allegrini, F.; McComas, D. J.; Louarn, P.

    2016-06-01

    We investigate the response function of an electrostatic analyzer when electron gyroradii in a magnetic field become comparable to the scale size of the sensor. This occurs when electrons have sufficiently small energies and are in a strong magnetic field. Through simulations and laboratory experiments with the Jovian Auroral Distribution Experiment-Electron (JADE-E) sensor, we observe the energy response, detection angle distribution, and geometric factor to change significantly. Using electro-optics simulation results, we develop semiempirical and empirical relationships that can be used for top hat electrostatic analyzers. We present a model based on these relationships that covers an energy range between 0.1 keV and 5 keV with a uniform external magnetic field magnitude between 0-3 G and verified that these relationships apply to JADE-E in a specially designed testing environment by comparing with the model. We find that the model agrees well with the JADE-E sensor validating it for top hat electrostatic analyzers more generally.

  6. Dipolar self-consistent field theory for ionic liquids between charged plates: Effects of dielectric contrast between cation and anion under external electrostatic fields

    NASA Astrophysics Data System (ADS)

    Nakamura, Issei

    We develop a new dipolar self-consistent field theory (DSCFT) for both incompressible and compressible ionic liquids under external electrostatic fields. Our theory accounts for the difference between the dipole moments and the molecular volumes of the cation and anion, and the double layer caused by the strong association of the ions with the electrodes. To date, few theoretical studies have considered the dielectric contrast between the cation and anion. Thus, our study focuses on the effect of the dielectric inhomogeneity on the ion distribution and the capacitance. Our theory shows that the capacitance changes with the applied voltage in agreement with experimental observations. Importantly, the dielectric contrast and the difference in molecular volumes between the cation and anion have equal effects on the magnitude of the capacitance. We also consider compressible ionic liquids by developing a hybrid of DSCFT combined with Monte Carlo simulations. We then demonstrate that the hard-core nature of the ions causes oscillations in the density profile and dielectric value near the charged plates. Accordingly, the dielectric constants derived from the classical theories of Onsager and Kirkwood are shown to be gross approximations of the true situation in nanochannels. National Natural Science Foundation of China (21474112).

  7. Field evaluation of a new particle concentrator- electrostatic precipitator system for measuring chemical and toxicological properties of particulate matter

    PubMed Central

    Ning, Zhi; Sillanpää, Markus; Pakbin, Payam; Sioutas, Constantinos

    2008-01-01

    Background A newly designed electrostatic precipitator (ESP) in tandem with Versatile Aerosol Concentration Enrichment System (VACES) was developed by the University of Southern California to collect ambient aerosols on substrates appropriate for chemical and toxicological analysis. The laboratory evaluation of this sampler is described in a previous paper. The main objective of this study was to evaluate the performance of the new VACES-ESP system in the field by comparing the chemical characteristics of the PM collected in the ESP to those of reference samplers operating in parallel. Results The field campaign was carried out in the period from August, 2007 to March, 2008 in a typical urban environment near downtown Los Angeles. Each sampling set was restricted to 2–3 hours to minimize possible sampling artifacts in the ESP. The results showed that particle penetration increases and ozone concentration decreases with increasing sampling flow rate, with highest particle penetration observed between 100 nm and 300 nm. A reference filter sampler was deployed in parallel to the ESP to collect concentration-enriched aerosols, and a MOUDI sampler was used to collect ambient aerosols. Chemical analysis results showed very good agreement between the ESP and MOUDI samplers in the concentrations of trace elements and inorganic ions. The overall organic compound content of PM collected by the ESP, including polycyclic aromatic hydrocarbons (PAHs), hopanes, steranes, and alkanes, was in good agreement with that of the reference sampler, with an average ESP -to -reference concentration ratio of 1.07 (± 0.38). While majority of organic compound ratios were close to 1, some of the semi-volatile organic species had slightly deviated ratios from 1, indicating the possibility of some sampling artifacts in the ESP due to reactions of PM with ozone and radicals generated from corona discharge, although positive and negative sampling artifacts in the reference filter sampler

  8. Electrostatics at the nanoscale

    SciTech Connect

    Walker, David A.; Kowalczyk, Bartlomiej; Olvera de la Cruz, Monica; Grzybowski, Bartosz A.

    2011-01-01

    Electrostatic forces are amongst the most versatile interactions to mediate the assembly of nanostructured materials. Depending on experimental conditions, these forces can be long- or short-ranged, can be either attractive or repulsive, and their directionality can be controlled by the shapes of the charged nano-objects. This Review is intended to serve as a primer for experimentalists curious about the fundamentals of nanoscale electrostatics and for theorists wishing to learn about recent experimental advances in the field. Accordingly, the first portion introduces the theoretical models of electrostatic double layers and derives electrostatic interaction potentials applicable to particles of different sizes and/or shapes and under different experimental conditions. This discussion is followed by the review of the key experimental systems in which electrostatic interactions are operative. Examples include electroactive and “switchable” nanoparticles, mixtures of charged nanoparticles, nanoparticle chains, sheets, coatings, crystals, and crystals-within-crystals. Applications of these and other structures in chemical sensing and amplification are also illustrated.

  9. Electrostatics at the nanoscale.

    PubMed

    Walker, David A; Kowalczyk, Bartlomiej; de la Cruz, Monica Olvera; Grzybowski, Bartosz A

    2011-04-01

    Electrostatic forces are amongst the most versatile interactions to mediate the assembly of nanostructured materials. Depending on experimental conditions, these forces can be long- or short-ranged, can be either attractive or repulsive, and their directionality can be controlled by the shapes of the charged nano-objects. This Review is intended to serve as a primer for experimentalists curious about the fundamentals of nanoscale electrostatics and for theorists wishing to learn about recent experimental advances in the field. Accordingly, the first portion introduces the theoretical models of electrostatic double layers and derives electrostatic interaction potentials applicable to particles of different sizes and/or shapes and under different experimental conditions. This discussion is followed by the review of the key experimental systems in which electrostatic interactions are operative. Examples include electroactive and "switchable" nanoparticles, mixtures of charged nanoparticles, nanoparticle chains, sheets, coatings, crystals, and crystals-within-crystals. Applications of these and other structures in chemical sensing and amplification are also illustrated.

  10. A theoretical analysis of HLA-DRbeta1*0301-CLIP complex using the first three multipolar moments of the electrostatic field.

    PubMed

    Balbín, Alejandro; Cárdenas, Constanza; Villaveces, José Luis; Patarroyo, Manuel E

    2006-09-01

    Interactions between the HLA-DRbeta1*0301 molecule and several occupying peptides obtained from computational substitutions made to the CLIP peptide are studied. The exploration was carried out using a vector composed of the first three terms of the multipolar expansion of the electrostatic field, namely, charge (q), dipole (d) and quadrupole (C). Comparisons between pocket-peptide interactions established that the binding pockets for this HLA molecule are ordered in terms of their importance for binding peptides, as follows: P1 > P4 > P6 > P7 > P9. A set of electrostatically distinct amino acids that determine interaction stability and specificity were identified for each pocket. The beta74R residue was especially identified as being the key amino acid mediating the occupying peptide binding for pocket 4; this residue has been recently associated with Graves' disease.

  11. Constraining electric fields from electrostatic deflector plates: A brief report and case study from the Fast Plasma Investigation for the Magnetospheric Multiscale Mission

    NASA Astrophysics Data System (ADS)

    Collinson, Glyn A.; McFadden, James P.; Chornay, Dennis J.; Gershman, Daniel; Moore, Thomas E.

    2016-08-01

    A common feature of top hat space plasma analyzers are electrostatic "deflector plates" mounted externally to the aperture which steer the incoming particles and permit the sensor to rapidly scan the sky without moving. However, the electric fields generated by these plates can penetrate the mesh or grid on the outside of the sensor, potentially violating spacecraft electromagnetic cleanliness requirements. In this brief report we discuss how this issue was addressed for the Dual Electron Spectrometer for the Magnetospheric Multiscale Mission using a double-grid system and the simple modeling technique employed to assure the safe containment of the stray fields from its deflector plates.

  12. Dynamic Coupling of Quasi-Electrostatic Thundercloud Fields to the Mesosphere and Lower Ionosphere: Sprites and Jets

    NASA Technical Reports Server (NTRS)

    Pasko, Victor Petrovich

    1996-01-01

    Red Sprites and Blue Jets are two different types of recently discovered optical flashes ob- served above large thunderstorm systems. Sprites are luminous glows occurring at altitudes typically ranging from approximately 50 to 90 km. In video they exhibit a red color at their top which gradually changes to blue at lower altitudes. Sprites may occur singly or in clusters of two or more. The lateral extent of "unit" sprites is typically 5-10 km and they endure for several milliseconds. Jets are upward moving (approximately 100 km/s) highly collimated beams of luminosity, emanating from the tops of thunderclouds, extending up to approximately 50 km altitude and exhibiting a primarily blue color. We propose that sprites result from large electric field transients capable of causing electron heating, breakdown ionization and excitation of optical emissions at mesospheric altitudes following the removal of thundercloud charge by a cloud-to-ground discharge. Depending on the history of charge accumulation and removal, and the distribution of ambient atmospheric conductivity, the breakdown region may have the shape of vertically oriented ionization column(s). Results of a two-dimensional and self consistent quasi-electrostatic (QE) model indicate that most of the observed features of sprites can be explained in terms of the formation and self-driven propagation of streamer type channels of breakdown ionization. Comparison of the optical emission intensities of the 1st and 2nd positive bands of N2, Meinel and 1st negative bands of N2(+) and the 1st negative band of O2(+) demonstrates that the 1st positive band of N2 is the dominant optical emission in the altitude range approximately 50-90 km, which accounts for the observed red color of sprites. Optical emissions of the 1st and 2nd positive bands of N2 occur in carrot-like vertical structures with typical transverse dimension approximately 5-10 km which can span an altitude range from approximately 80 km to well below

  13. Electrostatic monitoring

    DOEpatents

    Orr, Christopher Henry; Luff, Craig Janson; Dockray, Thomas; Macarthur, Duncan Whittemore

    2001-01-01

    The apparatus and method provide a technique for more simply measuring alpha and/or beta emissions arising from items or locations. The technique uses indirect monitoring of the emissions by detecting ions generated by the emissions, the ions being attracted electrostatically to electrodes for discharge of collection. The apparatus and method employ a chamber which is sealed around the item or location during monitoring with no air being drawn into or expelled from the chamber during the monitoring process. A simplified structure and operations arises as a result, but without impairing the efficiency and accuracy of the detection technique.

  14. Vibrational Stark Effect of the Electric-Field Reporter 4-Mercaptobenzonitrile as a Tool for Investigating Electrostatics at Electrode/SAM/Solution Interfaces

    PubMed Central

    Schkolnik, Gal; Salewski, Johannes; Millo, Diego; Zebger, Ingo; Franzen, Stefan; Hildebrandt, Peter

    2012-01-01

    4-mercaptobenzonitrile (MBN) in self-assembled monolayers (SAMs) on Au and Ag electrodes was studied by surface enhanced infrared absorption and Raman spectroscopy, to correlate the nitrile stretching frequency with the local electric field exploiting the vibrational Stark effect (VSE). Using MBN SAMs in different metal/SAM interfaces, we sorted out the main factors controlling the nitrile stretching frequency, which comprise, in addition to external electric fields, the metal-MBN bond, the surface potential, and hydrogen bond interactions. On the basis of the linear relationships between the nitrile stretching and the electrode potential, an electrostatic description of the interfacial potential distribution is presented that allows for determining the electric field strengths on the SAM surface, as well as the effective potential of zero-charge of the SAM-coated metal. Comparing this latter quantity with calculated values derived from literature data, we note a very good agreement for Au/MBN but distinct deviations for Ag/MBN which may reflect either the approximations and simplifications of the model or the uncertainty in reported structural parameters for Ag/MBN. The present electrostatic model consistently explains the electric field strengths for MBN SAMs on Ag and Au as well as for thiophenol and mercaptohexanoic acid SAMs with MBN incorporated as a VSE reporter. PMID:22837705

  15. Methods for high volume production of nanostructured materials

    DOEpatents

    Ripley, Edward B [Knoxville, TN; Morrell, Jonathan S [Knoxville, TN; Seals, Roland D [Oak Ridge, TN; Ludtka, Gerald M [Oak Ridge, TN

    2011-03-22

    A system and method for high volume production of nanoparticles, nanotubes, and items incorporating nanoparticles and nanotubes. Microwave, radio frequency, or infrared energy vaporizes a metal catalyst which, as it condenses, is contacted by carbon or other elements such as silicon, germanium, or boron to form agglomerates. The agglomerates may be annealed to accelerate the production of nanotubes. Magnetic or electric fields may be used to align the nanotubes during their production. The nanotubes may be separated from the production byproducts in aligned or non-aligned configurations. The agglomerates may be formed directly into tools, optionally in compositions that incorporate other materials such as abrasives, binders, carbon-carbon composites, and cermets.

  16. The self-consistent parallel electric field due to electrostatic ion-cyclotron turbulence in downward auroral-current regions of the Earth's magnetosphere. IV

    SciTech Connect

    Jasperse, John R.; Basu, Bamandas; Lund, Eric J.; Grossbard, Neil

    2010-06-15

    The physical processes that determine the self-consistent electric field (E{sub ||}) parallel to the magnetic field have been an unresolved problem in magnetospheric physics for over 40 years. Recently, a new multimoment fluid theory was developed for inhomogeneous, nonuniformly magnetized plasma in the guiding-center and gyrotropic approximation that includes the effect of electrostatic, turbulent, wave-particle interactions (see Jasperse et al. [Phys. Plasmas 13, 072903 (2006); ibid.13, 112902 (2006)]). In the present paper and its companion paper [Jasperse et al., Phys. Plasmas 17, 062903 (2010)], which are intended as sequels to the earlier work, a fundamental model for downward, magnetic field-aligned (Birkeland) currents for quasisteady conditions is presented. The model includes the production of electrostatic ion-cyclotron turbulence in the long-range potential region by an electron, bump-on-tail-driven ion-cyclotron instability. Anomalous momentum transfer (anomalous resistivity) by itself is found to produce a very small contribution to E{sub ||}; however, the presence of electrostatic, ion-cyclotron turbulence has a very large effect on the altitude dependence of the entire quasisteady solution. Anomalous energy transfer (anomalous heating and cooling) modifies the density, drift, and temperature altitude profiles and hence the generalized parallel-pressure gradients and mirror forces in the electron and ion momentum-balance equations. As a result, |E{sub ||}| is enhanced by nearly a factor of 40 compared to its value when turbulence is absent. The space-averaged potential increase associated with the strong double layer at the bottom of the downward-current sheet is estimated using the FAST satellite data and the multimoment fluid theory.

  17. Magnetosheath electrostatic turbulence

    NASA Technical Reports Server (NTRS)

    Rodriquez, P.

    1977-01-01

    The spectrum of electrostatic plasma waves in the terrestrial magnetosheath was studied using the plasma wave experiment on the IMP-6 satellite. Electrostatic plasma wave turbulence is almost continuously present throughout the magnetosheath with broadband (20 Hz- 70 kHz) r.m.s. field intensities typically 0.01 - 1.0 millivolts/m. Peak intensities of about 1.0 millivolts/m near the electron plasma frequency (30 - 60 kHz) were detected occasionally. The components usually identified in the spectrum of magnetosheath electrostatic turbulence include a high frequency ( or = 30 kHz) component peaking at the electron plasma frequency f sub pe, a low frequency component with a broad intensity maximum below the nominal ion plasma frequency f sub pi (approximately f sub pe/43), and a less well defined intermediate component in the range f sub pi f f sub pe. The intensity distribution of magnetosheath electrostatic turbulence clearly shows that the low frequency component is associated with the bow shock, suggesting that the ion heating begun at the shock continues into the downstream magnetosheath.

  18. Nanoscale Electrostatics in Mitosis

    NASA Astrophysics Data System (ADS)

    Gagliardi, L. John; West, Patrick Michael

    2001-04-01

    Primitive biological cells had to divide with very little biology. This work simulates a physicochemical mechanism, based upon nanoscale electrostatics, which explains the anaphase A poleward motion of chromosomes. In the cytoplasmic medium that exists in biological cells, electrostatic fields are subject to strong attenuation by Debye screening, and therefore decrease rapidly over a distance equal to several Debye lengths. However, the existence of microtubules within cells changes the situation completely. Microtubule dimer subunits are electric dipolar structures, and can act as intermediaries that extend the reach of the electrostatic interaction over cellular distances. Experimental studies have shown that intracellular pH rises to a peak at mitosis, and decreases through cytokinesis. This result, in conjunction with the electric dipole nature of microtubule subunits and the Debye screened electrostatic force is sufficient to explain and unify the basic events during mitosis and cytokinesis: (1) assembly of asters, (2) motion of the asters to poles, (3) poleward motion of chromosomes (anaphase A), (4) cell elongation, and (5) cytokinesis. This paper will focus on a simulation of the dynamics if anaphase A motion based on this comprehensive model. The physicochemical mechanisms utilized by primitive cells could provide important clues regarding our understanding of cell division in modern eukaryotic cells.

  19. Real-Time DC-dynamic Biasing Method for Switching Time Improvement in Severely Underdamped Fringing-field Electrostatic MEMS Actuators

    PubMed Central

    Small, Joshua; Fruehling, Adam; Garg, Anurag; Liu, Xiaoguang; Peroulis, Dimitrios

    2014-01-01

    Mechanically underdamped electrostatic fringing-field MEMS actuators are well known for their fast switching operation in response to a unit step input bias voltage. However, the tradeoff for the improved switching performance is a relatively long settling time to reach each gap height in response to various applied voltages. Transient applied bias waveforms are employed to facilitate reduced switching times for electrostatic fringing-field MEMS actuators with high mechanical quality factors. Removing the underlying substrate of the fringing-field actuator creates the low mechanical damping environment necessary to effectively test the concept. The removal of the underlying substrate also a has substantial improvement on the reliability performance of the device in regards to failure due to stiction. Although DC-dynamic biasing is useful in improving settling time, the required slew rates for typical MEMS devices may place aggressive requirements on the charge pumps for fully-integrated on-chip designs. Additionally, there may be challenges integrating the substrate removal step into the back-end-of-line commercial CMOS processing steps. Experimental validation of fabricated actuators demonstrates an improvement of 50x in switching time when compared to conventional step biasing results. Compared to theoretical calculations, the experimental results are in good agreement. PMID:25145811

  20. Real-time DC-dynamic biasing method for switching time improvement in severely underdamped fringing-field electrostatic MEMS actuators.

    PubMed

    Small, Joshua; Fruehling, Adam; Garg, Anurag; Liu, Xiaoguang; Peroulis, Dimitrios

    2014-08-15

    Mechanically underdamped electrostatic fringing-field MEMS actuators are well known for their fast switching operation in response to a unit step input bias voltage. However, the tradeoff for the improved switching performance is a relatively long settling time to reach each gap height in response to various applied voltages. Transient applied bias waveforms are employed to facilitate reduced switching times for electrostatic fringing-field MEMS actuators with high mechanical quality factors. Removing the underlying substrate of the fringing-field actuator creates the low mechanical damping environment necessary to effectively test the concept. The removal of the underlying substrate also a has substantial improvement on the reliability performance of the device in regards to failure due to stiction. Although DC-dynamic biasing is useful in improving settling time, the required slew rates for typical MEMS devices may place aggressive requirements on the charge pumps for fully-integrated on-chip designs. Additionally, there may be challenges integrating the substrate removal step into the back-end-of-line commercial CMOS processing steps. Experimental validation of fabricated actuators demonstrates an improvement of 50x in switching time when compared to conventional step biasing results. Compared to theoretical calculations, the experimental results are in good agreement.

  1. Electrostatic surface plasmon resonance: Direct electric field-induced hybridization and denaturation in monolayer nucleic acid films and label-free discrimination of base mismatches

    PubMed Central

    Heaton, Richard J.; Peterson, Alexander W.; Georgiadis, Rosina M.

    2001-01-01

    We demonstrate that in situ optical surface plasmon resonance spectroscopy can be used to monitor hybridization kinetics for unlabeled DNA in tethered monolayer nucleic acid films on gold in the presence of an applied electrostatic field. The dc field can enhance or retard hybridization and can also denature surface-immobilized DNA duplexes. Discrimination between matched and mismatched hybrids is achieved by simple adjustment of the electrode potential. Although the electric field at the interface is extremely large, the tethered single-stranded DNA thiol probes remain bound and can be reused for subsequent hybridization reactions without loss of efficiency. Only capacitive charging currents are drawn; redox reactions are avoided by maintaining the gold electrode potential within the ideally polarizable region. Because of potential-induced changes in the shape of the surface plasmon resonance curve, we account for the full curve rather than simply the shift in the resonance minimum. PMID:11259682

  2. Enhanced Selectivity for CO2 Adsorption on Mesoporous Silica with Alkali Metal Halide Due to Electrostatic Field: A Molecular Simulation Approach.

    PubMed

    Kwon, Soonchul; Kwon, Hyuk Jae; Choi, Ji Il; Kim, Ki Chul; Seo, Jeong Gil; Park, Jung Eun; You, Su Jin; Park, Eun Duck; Jang, Seung Soon; Lee, Hyun Chul

    2017-09-20

    Since adsorption performances are dominantly determined by adsorbate-adsorbent interactions, accurate theoretical prediction of the thermodynamic characteristics of gas adsorption is critical for designing new sorbent materials as well as understanding the adsorption mechanisms. Here, through our molecular modeling approach using a newly developed quantum-mechanics-based force field, it is demonstrated that the CO2 adsorption selectivity of SBA-15 can be enhanced by incorporating crystalline potassium chloride particles. It is noted that the induced intensive electrostatic fields around potassium chloride clusters create gas-trapping sites with high selectivity for CO2 adsorption. The newly developed force field can provide a reliable theoretical tool for accurately evaluating the gas adsorption on given adsorbents, which can be utilized to identify good gas adsorbents.

  3. High-volume haemofiltration for sepsis.

    PubMed

    Borthwick, Emma M J; Hill, Christopher J; Rabindranath, Kannaiyan S; Maxwell, Alexander P; McAuley, Danny F; Blackwood, Bronagh

    2013-01-31

    Severe sepsis and septic shock are leading causes of death in the intensive care unit (ICU). This is despite advances in the management of patients with severe sepsis and septic shock including early recognition, source control, timely and appropriate administration of antimicrobial agents, and goal directed haemodynamic, ventilatory and metabolic therapies. High-volume haemofiltration (HVHF) is a blood purification technique which may improve outcomes in critically ill patients with severe sepsis or septic shock. The technique of HVHF has evolved from renal replacement therapies used to treat acute kidney injury (AKI) in critically ill patients in the ICU. This review assessed whether HVHF improves clinical outcome in adult critically ill patients with sepsis in an ICU setting. We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, 2011, Issue 7); MEDLINE (1990 to August 2011), EMBASE (1990 to August 2011); LILACS (1982 to August 2011), Web of Science (1990 to August 2011), CINAHL (1982 to August 2011) and specific websites. We included randomized controlled trials (RCTs) and quasi-randomized trials comparing HVHF or high-volume haemodiafiltration to standard or usual dialysis therapy; and RCTs and quasi-randomized trials comparing HVHF or high-volume haemodiafiltration to no similar dialysis therapy. The studies involved adults in critical care units. Three review authors independently extracted data and assessed trial quality. We sought additional information as required from trialists. We included three randomized trials involving 64 participants. Due to the small number of studies and participants, it was not possible to combine data or perform sub-group analyses. One trial reported ICU and 28-day mortality, one trial reported hospital mortality and in the third, the number of deaths stated did not match the quoted mortality rates. No trials reported length of stay in ICU or hospital and one reported organ dysfunction

  4. High volume, multiple use, portable precipitator

    DOEpatents

    Carlson, Duane C [N. Augusta, SC

    2011-10-25

    A portable high air volume electrostatic collection precipitator for analyzing air is provided which is a relatively small, self-contained device. The device has a collection electrode adapted to carry a variety of collecting media. An air intake is provided such that air to be analyzed flows through an ionization section with a transversely positioned ionization wire to ionize analytes in the air, and then flows over the collection electrode where ionized analytes are collected. Air flow is maintained at but below turbulent flow, Ionizable constituents in the air are ionized, attracted to the collection electrode, and precipitated in the selected medium which can be removed for analysis.

  5. Public health and high volume hydraulic fracturing.

    PubMed

    Korfmacher, Katrina Smith; Jones, Walter A; Malone, Samantha L; Vinci, Leon F

    2013-01-01

    High-volume horizontal hydraulic fracturing (HVHF) in unconventional gas reserves has vastly increased the potential for domestic natural gas production. HVHF has been promoted as a way to decrease dependence on foreign energy sources, replace dirtier energy sources like coal, and generate economic development. At the same time, activities related to expanded HVHF pose potential risks including ground- and surface water contamination, climate change, air pollution, and effects on worker health. HVHF has been largely approached as an issue of energy economics and environmental regulation, but it also has significant implications for public health. We argue that public health provides an important perspective on policymaking in this arena. The American Public Health Association (APHA) recently adopted a policy position for involvement of public health professionals in this issue. Building on that foundation, this commentary lays out a set of five perspectives that guide how public health can contribute to this conversation.

  6. Optimizing the operating parameters of corona electrostatic separation for recycling waste scraped printed circuit boards by computer simulation of electric field.

    PubMed

    Li, Jia; Lu, Hongzhou; Liu, Shushu; Xu, Zhenming

    2008-05-01

    The printed circuit board (PCB) has a metal content of nearly 28% metal, including an abundance of nonferrous metals such as copper, lead, and tin. The purity of precious metals in PCBs is more than 10 times that of rich-content minerals. Therefore, the recycling of PCBs is an important subject, not only from the viewpoint of waste treatment, but also with respect to the recovery of valuable materials. Compared with traditional process the corona electrostatic separation (CES) had no waste water or gas during the process and it had high productivity with a low-energy cost. In this paper, the roll-type corona electrostatic separator was used to separate metals and nonmetals from scraped waste PCBs. The software MATLAB was used to simulate the distribution of electric field in separating space. It was found that, the variations of parameters of electrodes and applied voltages directly influenced the distribution of electric field. Through the correlation of simulated and experimental results, the good separation results were got under the optimized operating parameter: U=20-30 kV, L=L(1)=L(2)=0.21 m, R(1)=0.114, R(2)=0.019 m, theta(1)=20 degrees and theta(2)=60 degrees .

  7. An electrostatic ion pump with nanostructured Si field emission electron source and Ti particle collectors for supporting an ultra-high vacuum in miniaturized atom interferometry systems

    NASA Astrophysics Data System (ADS)

    Basu, Anirban; Velásquez-García, Luis F.

    2016-12-01

    We report a field emission-based, magnetic-less ion pump architecture for helping maintain a high vacuum within a small chamber that is compatible with miniaturized cold-atom interferometry systems. A nanostructured silicon field emitter array, with each nano-sharp tip surrounded by a self-aligned proximal gate electrode, is used to generate a surplus of electrons that cause impact ionization of gas molecules. A two-stage cylindrical electron collector, made of titanium, is used to increase the travel distance of the electrons, augmenting the ionization probability; gas ionization is subsequently followed by gettering of the ions by a negatively charged, annular-shaped titanium electrode. A proof-of-concept pump prototype was characterized using a 25 cm3 stainless steel vacuum chamber backed up by an external turbomolecular pump, a diaphragm pump, and a standard ion pump. Pumping action was observed with the electrostatic pump operating alone after an initial rapid rise of the chamber pressure due to electron/ion scrubbing. In addition, running the electrostatic pump in combination with the standard ion pump results in a lower vacuum level compared to the vacuum level produced by the standard ion pump acting alone. A proposed reduced-order model accurately predicts the functional dependence of the pressure versus time data and provides a good estimate of the characteristic pumping time constant inferred from the experiments.

  8. Micromachined silicon electrostatic chuck

    SciTech Connect

    Anderson, R.A.; Seager, C.H.

    1994-12-31

    In the field of microelectronics, and in particular the fabrication of microelectronics during plasma etching processes, electrostatic chucks have been used to hold silicon wafers during the plasma etching process. Current electrostatic chucks that operate by the {open_quotes}Johnson-Rahbek Effect{close_quotes} consist of a metallic base plate that is typically coated with a thick layer of slightly conductive dielectric material. A silicon wafer of approximately the same size as the chuck is placed on top of the chuck and a potential difference of several hundred volts is applied between the silicon and the base plate of the electrostatic chuck. This causes an electrostatic attraction proportional to the square of the electric field in the gap between the silicon wafer and the chuck face. When the chuck is used in a plasma filled chamber the electric potential of the wafer tends to be fixed by the effective potential of the plasma. The purpose of the dielectric layer on the chuck is to prevent the silicon wafer from coming into direct electrical contact with the metallic part of the chuck and shorting out the potential difference. On the other hand, a small amount of conductivity appears to be desirable in the dielectric coating so that much of its free surface between points of contact with the silicon wafer is maintained near the potential of the metallic base plate; otherwise, a much larger potential difference would be needed to produce a sufficiently large electric field in the vacuum gap between the wafer and chuck. Typically, the face of the chuck has a pattern of grooves in which about 10 torr pressure of helium gas is maintained. This gas provides cooling (thermal contact) between the wafer and the chuck. A pressure of 10 torr is equivalent to about 0.2 psi.

  9. SIRAH: a structurally unbiased coarse-grained force field for proteins with aqueous solvation and long-range electrostatics.

    PubMed

    Darré, Leonardo; Machado, Matías Rodrigo; Brandner, Astrid Febe; González, Humberto Carlos; Ferreira, Sebastián; Pantano, Sergio

    2015-02-10

    Modeling of macromolecular structures and interactions represents an important challenge for computational biology, involving different time and length scales. However, this task can be facilitated through the use of coarse-grained (CG) models, which reduce the number of degrees of freedom and allow efficient exploration of complex conformational spaces. This article presents a new CG protein model named SIRAH, developed to work with explicit solvent and to capture sequence, temperature, and ionic strength effects in a topologically unbiased manner. SIRAH is implemented in GROMACS, and interactions are calculated using a standard pairwise Hamiltonian for classical molecular dynamics simulations. We present a set of simulations that test the capability of SIRAH to produce a qualitatively correct solvation on different amino acids, hydrophilic/hydrophobic interactions, and long-range electrostatic recognition leading to spontaneous association of unstructured peptides and stable structures of single polypeptides and protein-protein complexes.

  10. Formation of an intense pulsed beam of CH3Cl in the ‖111≳ state using a 2-m electrostatic hexapole field

    NASA Astrophysics Data System (ADS)

    Kasai, T.; Fukawa, T.; Matsunami, T.; Che, D.-C.; Ohashi, K.; Fukunishi, Y.; Ohoyama, H.; Kuwata, K.

    1993-05-01

    An intense pulsed beam of CH3Cl in the ‖111≳ state without velocity selection was focused using a 2-m electrostatic hexapole field. The beam intensity was estimated to be ˜1×1013 molecules pulse-1, which is much greater than the similar beams in the earlier study of Gandhi et al. by at least two orders of magnitude. The beam had a 3-ms pulse width and was focused with an angular divergence of 0.7 mrad. The improvements in beam intensity and in the divergence of the beam can be mainly ascribable to the efficient pumping of the hexapole field through the cylindrical electrodes, which enables us to employ the helium seeding to have the fast stream velocity, the narrow distribution of velocity, and the aerodynamic effects. Those factors altogether made the velocity selection of the beam unnecessary.

  11. Electrostatic curtain studies

    SciTech Connect

    Meyer, L C

    1992-05-01

    This report presents the results of experiments using electrostatic curtains (ESCS) as a transuranic (TRU) contamination control technique. The TRU contaminants included small (micrometer to sub micrometer) particles of plutonium and americium compounds associated with defense-related waste. Three series of experiments were conducted. The first was with uncontaminated Idaho National Engineering Laboratory (INEL) soil, the second used contaminated soil containing plutonium-239 (from a mixture of Rocky Flats Plant contaminated soil and INEL uncontaminated soil), and the third was uncontaminated INEL soil spiked with plutonium-239. All experiments with contaminated soil were conducted inside a glove box containing a dust generator, low volume cascade impactor (LVCI), electrostatic separator, and electrostatic materials. The data for these experiments consisted of the mass of dust collected on the various material coupons, plates, and filters; radiochemical analysis of selected samples; and photographs, as well as computer printouts giving particle size distributions and dimensions from the scanning electron microscope (SEM). The following results were found: (a) plutonium content (pCi/g) was found to increase with smaller soil particle sizes and (b) the electrostatic field had a stronger influence on smaller particle sizes compared to larger particle sizes. The SEM analysis indicated that the particle size of the tracer Pu239 used in the spiked soil experiments was below the detectable size limit (0.5 {mu}m) of the SEM and, thus, may not be representative of plutonium particles found in defense-related waste. The use of radiochemical analysis indicated that plutonium could be found on separator plates of both polarities, as well as passing through the electric field and collecting on LVCI filters.

  12. The non-dominance of counterions in charge-asymmetric electrolytes: non-monotonic precedence of electrostatic screening and local inversion of the electric field by multivalent coions.

    PubMed

    Guerrero-García, Guillermo Iván; González-Tovar, Enrique; Quesada-Pérez, Manuel; Martín-Molina, Alberto

    2016-08-03

    The asymptotic convergence of the thermodynamic and structural properties of unequally-sized charge-symmetric ions in strong electric fields was postulated more than thirty years ago by Valleau and Torrie as the dominance of counterions via the non-linear Poisson-Boltzmann theory [Valleau and Torrie, J. Chem. Phys., 1982, 76, 4623]. According to this mean field prescription, the properties of the electrical double layer near a highly charged electrode immersed in a size-asymmetric binary electrolyte converge to those of a size-symmetric electrolyte if the properties of counterions are the same in both instances. On the other hand, some of the present authors have shown that, in fact, counterions do not dominate the electrical properties of a spherical macroion in the presence of unequally-sized ions, symmetric in valence, if ion correlations and ionic excluded volume effects are taken into account consistently. These ingredients are neglected in the classical Poisson-Boltzmann picture. In the present work, we show the occurrence of the non-dominance of counterions in the opposite scenario, that is, when ions are equally-sized but asymmetric in valence. This is performed in the presence of highly charged colloidal surfaces of spherical and planar geometries for different ionic volume fractions. In addition to the phenomenon of non-dominance of counterions, our simulations and theoretical data also exhibit a non-monotonic order or precedence in the mean electrostatic potential, or electrostatic screening, at the Helmholtz plane of a charged colloid. This interesting behaviour is analyzed as a function of the coion's valence, the ionic volume fraction, and the charge and size of the colloidal particle. All these phenomena are explained in terms of the decay of the electric field near the colloidal surface, and by the appearance of a local inversion of both the electric field and the integrated surface charge density of the colloidal particle in the presence of

  13. Worldwide high-volume coal ash utilization

    SciTech Connect

    Manz, O.E.

    1999-11-01

    Coal ash refers to fly ash as well as bottom ash and boiler slag. High-volume uses include those fly ash products that are either large in quantity or use huge percentages (over 50%) of fly ash. High-volume uses are typified by fills, embankments, backfills, highway base course, and soil stabilization and amendment. In 1992, 367 million tonnes of fly ash were produced, as well as 91.8 million tonnes of bottom ash and boiler slag; 152.8 million tonnes (33.3%) were used. The main uses of coal ash have been in cement and concrete manufacture, in road construction and as filler on construction sites, in cellular concrete, and in lightweight aggregate and brick. Worldwide in 1992, 40.2 million tonnes were used in cement and concrete manufacture; 47.5 million tonnes in road construction and as filler on construction sites, in cellular concrete, and in lightweight aggregate and brick. Worldwide in 1992, 40.2 million tonnes were used in cement and concrete manufacture; 47.5 million tonnes in road construction and as filler on construction sites; 7.2 million tonnes in cellular concrete; 3.1 million tonnes in lightweight aggregate and bricks; over 40 million tonnes for filler for mines, quarries, or pits; and almost 3 million tonnes for soil amendment. EPRI (the collaborative R and D organization with membership of over 700 electric utilities) initiated an ash utilization research and development program in 1979 aimed at supporting the increased use of fly ash in the United States. This paper includes a worldwide survey of the production and utilization of coal ash from 1964 to 1995. The data were collected from various working papers of the UN Group of Experts on the Utilization of Ash and from three papers by the author on the worldwide production and utilization of coal ash. For 1995, information was obtained through a questionnaire sent to selected individuals. The last available data for eastern Europe and the United Kingdom are for 1989.

  14. Electrostatic potential map modelling with COSY Infinity

    NASA Astrophysics Data System (ADS)

    Maloney, J. A.; Baartman, R.; Planche, T.; Saminathan, S.

    2016-06-01

    COSY Infinity (Makino and Berz, 2005) is a differential-algebra based simulation code which allows accurate calculation of transfer maps to arbitrary order. COSY's existing internal procedures were modified to allow electrostatic elements to be specified using an array of field potential data from the midplane. Additionally, a new procedure was created allowing electrostatic elements and their fringe fields to be specified by an analytic function. This allows greater flexibility in accurately modelling electrostatic elements and their fringe fields. Applied examples of these new procedures are presented including the modelling of a shunted electrostatic multipole designed with OPERA, a spherical electrostatic bender, and the effects of different shaped apertures in an electrostatic beam line.

  15. Versatile electrostatic trap

    SciTech Connect

    Veldhoven, Jacqueline van; Bethlem, Hendrick L.; Schnell, Melanie; Meijer, Gerard

    2006-06-15

    A four electrode electrostatic trap geometry is demonstrated that can be used to combine a dipole, quadrupole, and hexapole field. A cold packet of {sup 15}ND{sub 3} molecules is confined in both a purely quadrupolar and hexapolar trapping field and additionally, a dipole field is added to a hexapole field to create either a double-well or a donut-shaped trapping field. The profile of the {sup 15}ND{sub 3} packet in each of these four trapping potentials is measured, and the dependence of the well-separation and barrier height of the double-well and donut potential on the hexapole and dipole term are discussed.

  16. Program PROTEUS for adding hydrogens to a protein structure and electrostatic field across carotenoids in light harvesting complexes and reaction centers from bacterial sources

    NASA Astrophysics Data System (ADS)

    Lipovaca, Samir

    The hydrogen construction method presented in the program PROTEUS treats hydrogens depending on their torsional degrees of freedom. The positions of hydrogens with restricted torsional degrees of freedom are completely determined by the heavy atoms positions in the structure. The hydroxyl and water hydrogens are the only hydrogens that PROTEUS accepts as movable hydrogens (having rotational degrees of freedom). Their positions are determined by the interactions with neighboring atoms. PROTEUS interaction energy corresponds to a view that the hydrogen bond is affected, besides electrostatic effects and steric constraints of neighboring groups, by an inherent energy barrier that opposes free rotation of the hydroxyl hydrogen. For the water hydrogens that barrier is zero. The hydroxyl and water hydrogens are minimized within a short distance using the Threshold Accepting (TA) energy minimization method. PROTEUS can provide reasonable positions of movable hydrogens and a good initial protein structure for further investigations. We applied the program PROTEUS to place hydrogens in several resolved three-dimensional crystal structures of light harvesting complexes (LHCs) and reaction centers (RCs) from bacterial sources. Using program DelPhi we calculated the local electrostatic field across carotenoid generated by the protein's charges. In each structure we identified amino acids responsible for the field. Much of the field is generated by the charged residues. There are different ways that a RC or LHC uses charged residues. A nearby dipole consisting of the charged residues which are ionized in the physiological pH range (like Arg-Asp), is often used. Clusters of charged residues or scattered isolated charged residues around the carotenoid molecule also contribute. The polarizable field is not necessarily along the carotenoid molecule principal axis. For soluble LHCs the contribution of polar residues to the field cannot be neglected. Our calculations indicate an

  17. Influence of electrostatic forces on particle propulsion in the evanescent field of silver ion-exchanged waveguides.

    PubMed

    Gebennikov, Dmytro; Mittler, Silvia

    2013-02-26

    The effect of electrostatic interaction between carboxylate- and amino-functionalized polystyrene particles and a charged waveguide surface on the propulsion speed in optical tweezers is considered to be a function of the pH and ionic strength. It was shown that with the variation of the pH of the aqueous solution in which the particles were immersed, a systematic change in propulsion speed with a maximum speed could be achieved. The appearance of a maximum speed was ascribed to changes in the particle-waveguide separation as a result of the combination of two forces: Coulomb repulsion/attraction and induced dipole forces. The highest maximum speed at low ionic strength was around 12 μm/s. Changes in the ionic strength of the solution influenced the gradient of the dielectric constant near the involved surfaces and also led to a slightly reduced hydrodynamic radius of the particles. The combination of these effects subsequently increased the maximum speed to about 23 μm/s.

  18. Ion source for desportion and ionization in strong electrostatic field for MKh1320 high-resolution mass spectrometer

    SciTech Connect

    Golovatyi, V.G.; Shabel'nikov, V.P.; Shpakovskii, I.V.

    1986-06-01

    This paper describes an ion source for an MKh1320 mass spectrometer for field desorption studies. The ion current of the main component recorded by the collector of the mass spectrometer is 10/sup -12/ A and the resolution is ca 1000. Tri-p-bromotriphenylamine (stable aromatic cation radical) was studied to determine the resolution of the mass spectrometer in the field desorption mode. A field desorption mass spectrum of this material with the emitter at room temperature is shown. The field desorption ion source can be used with IE-26, IE-26M, and/or IEP-23 industrial ion sources.

  19. Electrostatic disturbances aboard LISA Pathfinder

    NASA Astrophysics Data System (ADS)

    Ferroni, Valerio

    Test mass charging and stray electrostatic fields are a potentially important source of force noise for the LISA Pathfinder mission. During the flight we plan to measure the relevant stray electrostatic fields on the surfaces of both the test mass and the electrode housing and compensate them with DC electrode bias voltages. In addition we monitor the charge and reduce it to near zero by UV illumination. We describe the analysis techniques used during the mission and explain the importance of periodic charging/discharging and of long-term charge measurements to limit the force noise at low frequency, which is particularly relevant for the eLISA mission.

  20. Charge sniffer for electrostatics demonstrations

    NASA Astrophysics Data System (ADS)

    Dinca, Mihai P.

    2011-02-01

    An electronic electroscope with a special design for demonstrations and experiments on static electricity is described. It operates as an electric charge sniffer by detecting slightly charged objects when they are brought to the front of its sensing electrode. The sniffer has the advantage of combining high directional sensitivity with a logarithmic bar display. It allows for the identification of electric charge polarity during charge separation by friction, peeling, electrostatic induction, batteries, or secondary coils of power transformers. Other experiments in electrostatics, such as observing the electric field of an oscillating dipole and the distance dependence of the electric field generated by simple charge configurations, are also described.

  1. Innovative Electrostatic Adhesion Technologies

    NASA Astrophysics Data System (ADS)

    Gagliano, L.; Bryan, T.; Williams, S.; McCoy, B.; MacLeod, T.

    Developing specialized Electro-Static grippers (commercially used in Semiconductor Manufacturing and in package handling) will allow gentle and secure Capture, Soft Docking, and Handling of a wide variety of materials and shapes (such as upper-stages, satellites, arrays, and possibly asteroids) without requiring physical features or cavities for a pincher or probe or using harpoons or nets. Combined with new rigid boom mechanisms or small agile chaser vehicles, flexible, high speed Electro-Static Grippers can enable compliant capture of spinning objects starting from a safe stand-off distance. Electroadhesion (EA) can enable lightweight, ultra-low-power, compliant attachment in space by using an electrostatic force to adhere similar and dissimilar surfaces. A typical EA enabled device is composed of compliant space-rated materials, such as copper-clad polyimide encapsulated by polymers. Attachment is induced by strong electrostatic forces between any substrate material, such as an exterior satellite panel and a compliant EA surface. When alternate positive and negative charges are induced in adjacent planar electrodes in an EA surface, the electric fields set up opposite charges on the substrate and cause an electrostatic adhesion between the electrodes and the induced charges on the substrate. Since the electrodes and the polymer are compliant and can conform to uneven or rough surfaces, the electrodes can remain intimately close to the entire surface, enabling high clamping pressures. Clamping pressures of more than 3 N/cm2 in shear can be achieved on a variety of substrates with ultra-low holding power consumption (measured values are less than 20 microW/Newton weight held). A single EA surface geometry can be used to clamp both dielectric and conductive substrates, with slightly different physical mechanisms. Furthermore EA clamping requires no normal force be placed on the substrate, as conventional docking requires. Internally funded research and development

  2. Innovative Electrostatic Adhesion Technologies

    NASA Technical Reports Server (NTRS)

    Bryan, Tom; Macleod, Todd; Gagliano, Larry; Williams, Scott; McCoy, Brian

    2015-01-01

    Developing specialized Electro-Static grippers (commercially used in Semiconductor Manufacturing and in package handling) will allow gentle and secure Capture, Soft Docking, and Handling of a wide variety of materials and shapes (such as upper-stages, satellites, arrays, and possibly asteroids) without requiring physical features or cavities for a pincher or probe or using harpoons or nets. Combined with new rigid boom mechanisms or small agile chaser vehicles, flexible, high speed Electro-Static Grippers can enable compliant capture of spinning objects starting from a safe stand-off distance. Electroadhesion (EA) can enable lightweight, ultra-low-power, compliant attachment in space by using an electrostatic force to adhere similar and dissimilar surfaces. A typical EA enabled device is composed of compliant space-rated materials, such as copper-clad polyimide encapsulated by polymers. Attachment is induced by strong electrostatic forces between any substrate material, such as an exterior satellite panel and a compliant EA gripper pad surface. When alternate positive and negative charges are induced in adjacent planar electrodes in an EA surface, the electric fields set up opposite charges on the substrate and cause an electrostatic adhesion between the electrodes and the induced charges on the substrate. Since the electrodes and the polymer are compliant and can conform to uneven or rough surfaces, the electrodes can remain intimately close to the entire surface, enabling high clamping pressures. Clamping pressures of more than 3 N/cm2 in shear can be achieved on a variety of substrates with ultra-low holding power consumption (measured values are less than 20 microW/Newton weight held). A single EA surface geometry can be used to clamp both dielectric and conductive substrates, with slightly different physical mechanisms. Furthermore EA clamping requires no normal force be placed on the substrate, as conventional docking requires. Internally funded research and

  3. A distributed electrostatic model for field gradients at nuclei in van der Waals molecules: application to complexes of HCl

    NASA Astrophysics Data System (ADS)

    Buckingham, A. D.; Fowler, P. W.; Legon, A. C.; Peebles, S. A.; Steiner, E.

    1995-01-01

    A distributed model for the response of the electric field gradient at a nucleus to perturbation by external fields is proposed, and an implementation using perturbation of distributed multipole moments by a test nuclear quadrupole is described. Calculations on the HCl and Cl 2 molecules show the response of the electric field gradient at Cl to be dominated by induced σ charge flow. Application to hydrogen-bonded complexes of HCl gives a qualitative explanation of 35Cl quadrupole coupling constants in B…HCl where B is a base such as H 3N, HCN, CH 3CN, H 3P and OC.

  4. Spacecraft Electrostatic Radiation Shielding

    NASA Technical Reports Server (NTRS)

    2008-01-01

    This project analyzed the feasibility of placing an electrostatic field around a spacecraft to provide a shield against radiation. The concept was originally proposed in the 1960s and tested on a spacecraft by the Soviet Union in the 1970s. Such tests and analyses showed that this concept is not only feasible but operational. The problem though is that most of this work was aimed at protection from 10- to 100-MeV radiation. We now appreciate that the real problem is 1- to 2-GeV radiation. So, the question is one of scaling, in both energy and size. Can electrostatic shielding be made to work at these high energy levels and can it protect an entire vehicle? After significant analysis and consideration, an electrostatic shield configuration was proposed. The selected architecture was a torus, charged to a high negative voltage, surrounding the vehicle, and a set of positively charged spheres. Van de Graaff generators were proposed as the mechanism to move charge from the vehicle to the torus to generate the fields necessary to protect the spacecraft. This design minimized complexity, residual charge, and structural forces and resolved several concerns raised during the internal critical review. But, it still is not clear if such a system is costeffective or feasible, even though several studies have indicated usefulness for radiation protection at energies lower than that of the galactic cosmic rays. Constructing such a system will require power supplies that can generate voltages 10 times that of the state of the art. Of more concern is the difficulty of maintaining the proper net charge on the entire structure and ensuring that its interaction with solar wind will not cause rapid discharge. Yet, if these concerns can be resolved, such a scheme may provide significant radiation shielding to future vehicles, without the excessive weight or complexity of other active shielding techniques.

  5. Electrostatic field measurements and band flattening during electron-transfer processes at single-crystal TiO[sub 2] electrodes by electric field-induced optical second harmonic generation

    SciTech Connect

    Lantz, J.M.; Corn, R.M. )

    1994-05-05

    Optical second harmonic generation (SHG) is employed as a local, time-resolved measurement of the electrostatic fields at the surface of single-crystal TiO[sub 2] electrodes in contact with aqueous electrolyte solutions. The interfacial SHG at a fundamental wavelength of 584 nm is dominated by the electric field-induced second harmonic (EFISH) response from the first 20 nm of the space charge layer at the surface of the semiconductor. A substantial decrease in the amount of SHG from the electrode while under potentiostatic control is observed upon illumination of the surface with UV light (320 nm) whose energy is above the bandgap for TiO[sub 2] (3.0 eV or 410 nm). Comparisons of the drop in SHG upon UV illumination with photovoltage measurements for TiO[sub 2] electrodes at open circuit verify that this decrease is due to a reduction in the strength of the electrostatic fields ([open quotes]band flattening[close quotes]) within the space charge region upon UV illumination. The EFISH response from the surface decreases with increasing power of the UV illumination, corresponding to a band flattening of up to 70% for the highest power densities. Upon termination of the UV illumination, a slow (10-12 s) rise time is observed for the return of the surface SHG to its normal levels. 50 refs., 8 figs.

  6. Field-aligned Currents Induced by Electrostatic Polarization at the Ionosphere: Application to the Poleward Boundary Intensification (PBI) of Auroral Emission

    NASA Astrophysics Data System (ADS)

    Ohtani, S.; Yoshikawa, A.

    2016-12-01

    Although the field-aligned currents (Birkeland currents) are generally considered to be driven by magnetospheric processes, it is possible that some field-aligned currents are locally induced in the ionosphere in the presence of sharp conductance gradient. In this presentation we shall discuss the poleward boundary intensification (PBI) of auroral emission as an example effect of such electrostatic polarization. The observations show that the PBIs are very often preceded by the fast polar cap convection approaching the nightside auroral oval. We propose that the ionospheric currents driven by the associated electric field diverges/converges at the poleward boundary of the auroral oval as the background ionospheric conductance changes sharply in space, and they close with field-aligned currents. The associated upward field-aligned current is accompanied by electron precipitation, which may cause auroral emission as observed as PBIs. We test this idea by modeling the ionosphere as a slab-shaped enhancement of conductance and the polar cap flow channel as a pair of upward and downward FACs. The results show that (i) a pair of upward and downward FACs is induced at the poleward boundary when the front of the polar cap flow channel approaches the auroral oval; (ii) the upward FAC extends westward much wider in longitude than the flow channel; (iii) the peak FAC density is significantly larger than the incident FAC; and (iv) the induced upward and downward FACs are distributed almost symmetrically in longitude, indicating that the Pedersen polarization dominates the Hall polarization. These results are consistent with some general characteristics of PBIs, which are rather difficult to explain if the PBIs are the ionospheric manefestation of distant reconnection as often suggested.

  7. Using Programmable Calculators to Solve Electrostatics Problems.

    ERIC Educational Resources Information Center

    Yerian, Stephen C.; Denker, Dennis A.

    1985-01-01

    Provides a simple routine which allows first-year physics students to use programmable calculators to solve otherwise complex electrostatic problems. These problems involve finding electrostatic potential and electric field on the axis of a uniformly charged ring. Modest programing skills are required of students. (DH)

  8. Tailoring plasmonic and electrostatic field effects to maximize solar energy conversion by bacteriorhodopsin, the other natural photosynthetic system.

    PubMed

    Yen, Chun-Wan; Hayden, Steven C; Dreaden, Erik C; Szymanski, Paul; El-Sayed, Mostafa A

    2011-09-14

    We have explored the plasmonic field enhancement of current production from bacteriorhodopsin (bR) by maximizing the blue light effect, where the influx of blue photons absorbed by the long-lived M intermediate drastically shortens the time scale of the bR photocycle, leading to current enhancement. To this end, we used three approaches in our solution-based cell: (1) We improved the charge carrier separation in solution through the use of a proton-selective Nafion membrane. (2) We maximized the plasmonic surface field effects by selecting the capping polymer with minimum surface field screening and best nanoparticle stability. (3) We selected the plasmonic nanoparticle with the strongest plasmonic field whose surface plasmon resonance has the largest spectral overlap with the blue light absorbing M-intermediate. Theoretical models are used to explain experimental results, which show a 40 nm cuboidal nanoparticle capped with 55k PVP polymer to give the best photocurrent enhancement. Enhanced by this particle, bR in our Nafion membrane solution cell gave a photocurrent of 0.21 μA/cm(3), which is 5000 times larger than the published results for thin film bR electrochemical cells even with an applied bias. Additional possible enhancements are proposed.

  9. Built-in microscale electrostatic fields induced by anatase–rutile-phase transition in selective areas promote osteogenesis

    PubMed Central

    Ning, Chengyun; Yu, Peng; Zhu, Ye; Yao, Mengyu; Zhu, Xiaojing; Wang, Xiaolan; Lin, Zefeng; Li, Weiping; Wang, Shuangying; Tan, Guoxin; Zhang, Yu; Wang, Yingjun; Mao, Chuanbin

    2016-01-01

    Bone has a built-in electric field because of the presence of piezoelectric collagen. To date, only externally applied electric fields have been used to direct cell behavior; however, these fields are not safe or practical for in vivo use. In this work, for the first time, we use a periodic microscale electric field (MEF) built into a titanium implant to induce osteogenesis. Such a MEF is generated by the periodic organization of a junction made of two parallel semiconducting TiO2 zones: anatase and rutile with lower and higher electron densities, respectively. The junctions were formed through anatase–rutile-phase transition in selective areas using laser irradiation on the implants. The in vitro and in vivo studies confirmed that the built-in MEF was an efficient electrical cue for inducing osteogenic differentiation in the absence of osteogenic supplements and promoted bone regeneration around the implants. Our work opens up a new avenue toward bone repair and regeneration using built-in MEF. PMID:27818718

  10. Electrostatic Insect Sweeper for Eliminating Whiteflies Colonizing Host Plants: A Complementary Pest Control Device in An Electric Field Screen-Guarded Greenhouse

    PubMed Central

    Takikawa, Yoshihiro; Matsuda, Yoshinori; Kakutani, Koji; Nonomura, Teruo; Kusakari, Shin-ichi; Okada, Kiyotsugu; Kimbara, Junji; Osamura, Kazumi; Toyoda, Hideyoshi

    2015-01-01

    Our greenhouse tomatoes have suffered from attacks by viruliferous whiteflies Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) over the last 10 years. The fundamental countermeasure was the application of an electric field screen to the greenhouse windows to prevent their entry. However, while the protection was effective, it was incomplete, because of the lack of a guard at the greenhouse entrance area; in fact, the pests entered from the entrance door when workers entered and exited. To address this, we developed a portable electrostatic insect sweeper as a supplementary technique to the screen. In this sweeper, eight insulated conductor wires (ICWs) were arranged at constant intervals along a polyvinylchloride (PVC) pipe and covered with a cylindrical stainless net. The ICWs and metal net were linked to a DC voltage generator (operated by 3-V alkaline batteries) inside the grip and oppositely electrified to generate an electric field between them. Whiteflies on the plants were attracted to the sweeper that was gently slid along the leaves. This apparatus was easy to operate on-site in a greenhouse and enabled capture of the whiteflies detected during the routine care of the tomato plants. Using this apparatus, we caught all whiteflies that invaded the non-guarded entrance door and minimized the appearance and spread of the viral disease in tomato plants in the greenhouse. PMID:26463195

  11. Control of ion gyroscale fluctuations via electrostatic biasing and sheared E×B flow in the C-2 field reversed configuration

    NASA Astrophysics Data System (ADS)

    Schmitz, L.; Ruskov, E.; Deng, B. H.; Binderbauer, M.; Tajima, T.; Gota, H.; Tuszewski, M.

    2016-03-01

    Control of radial particle and thermal transport is instrumental for achieving and sustaining well-confined high-β plasma in a Field-Reversed Configuration (FRC). Radial profiles of low frequency ion gyro-scale density fluctuations (0.5≤kρs≤40), consistent with drift- or drift-interchange modes, have been measured in the scrape-off layer (SOL) and core of the C-2 Field-Reversed Configuration (FRC), together with the toroidal E×B velocity. It is shown here that axial electrostatic SOL biasing controls and reduces gyro-scale density fluctuations, resulting in very low FRC core fluctuation levels. When the radial E×B flow shearing rate decreases below the turbulence decorrelation rate, fluctuation levels increase substantially, concomitantly with onset of the n=2 instability and rapid loss of diamagnetism. Low turbulence levels, improved energy/particle confinement and substantially increased FRC life times are achieved when E×B shear near the separatrix is maintained via axial SOL biasing using an annular washer gun.

  12. Electrostatic frequency maps for amide-I mode of β-peptide: Comparison of molecular mechanics force field and DFT calculations

    NASA Astrophysics Data System (ADS)

    Cai, Kaicong; Zheng, Xuan; Du, Fenfen

    2017-08-01

    The spectroscopy of amide-I vibrations has been widely utilized for the understanding of dynamical structure of polypeptides. For the modeling of amide-I spectra, two frequency maps were built for β-peptide analogue (N-ethylpropionamide, NEPA) in a number of solvents within different schemes (molecular mechanics force field based, GM map; DFT calculation based, GD map), respectively. The electrostatic potentials on the amide unit that originated from solvents and peptide backbone were correlated to the amide-I frequency shift from gas phase to solution phase during map parameterization. GM map is easier to construct with negligible computational cost since the frequency calculations for the samples are purely based on force field, while GD map utilizes sophisticated DFT calculations on the representative solute-solvent clusters and brings insight into the electronic structures of solvated NEPA and its chemical environments. The results show that the maps' predicted amide-I frequencies present solvation environmental sensitivities and exhibit their specific characters with respect to the map protocols, and the obtained vibrational parameters are in satisfactory agreement with experimental amide-I spectra of NEPA in solution phase. Although different theoretical schemes based maps have their advantages and disadvantages, the present maps show their potentials in interpreting the amide-I spectra for β-peptides, respectively.

  13. Toward an Understanding of the Electric Field-Induced Electrostatic Doping in van der Waals Heterostructures: A First-Principles Study.

    PubMed

    Lu, Anh Khoa Augustin; Houssa, Michel; Radu, Iuliana P; Pourtois, Geoffrey

    2017-03-01

    Since the discovery of graphene, a broad range of two-dimensional (2D) materials has captured the attention of the scientific communities. Materials, such as hexagonal boron nitride (hBN) and the transition metal dichalcogenides (TMDs) family, have shown promising semiconducting and insulating properties that are very appealing for the semiconductor industry. Recently, the possibility of taking advantage of the properties of 2D-based heterostructures has been investigated for low-power nanoelectronic applications. In this work, we aim at evaluating the relation between the nature of the materials used in such heterostructures and the amplitude of the layer-to-layer charge transfer induced by an external electric field, as is typically present in nanoelectronic gated devices. A broad range of combinations of TMDs, graphene, and hBN has been investigated using density functional theory. Our results show that the electric field induced charge transfer strongly depends on the nature of the 2D materials used in the van der Waals heterostructures and to a lesser extent on the relative orientation of the materials in the structure. Our findings contribute to the building of the fundamental understanding required to engineer electrostatically the doping of 2D materials and to establish the factors that drive the charge transfer mechanisms in electron tunneling-based devices. These are key ingredients for the development of 2D-based nanoelectronic devices.

  14. Electrostatic Insect Sweeper for Eliminating Whiteflies Colonizing Host Plants: A Complementary Pest Control Device in An Electric Field Screen-Guarded Greenhouse.

    PubMed

    Takikawa, Yoshihiro; Matsuda, Yoshinori; Kakutani, Koji; Nonomura, Teruo; Kusakari, Shin-Ichi; Okada, Kiyotsugu; Kimbara, Junji; Osamura, Kazumi; Toyoda, Hideyoshi

    2015-05-12

    Our greenhouse tomatoes have suffered from attacks by viruliferous whiteflies Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) over the last 10 years. The fundamental countermeasure was the application of an electric field screen to the greenhouse windows to prevent their entry. However, while the protection was effective, it was incomplete, because of the lack of a guard at the greenhouse entrance area; in fact, the pests entered from the entrance door when workers entered and exited. To address this, we developed a portable electrostatic insect sweeper as a supplementary technique to the screen. In this sweeper, eight insulated conductor wires (ICWs) were arranged at constant intervals along a polyvinylchloride (PVC) pipe and covered with a cylindrical stainless net. The ICWs and metal net were linked to a DC voltage generator (operated by 3-V alkaline batteries) inside the grip and oppositely electrified to generate an electric field between them. Whiteflies on the plants were attracted to the sweeper that was gently slid along the leaves. This apparatus was easy to operate on-site in a greenhouse and enabled capture of the whiteflies detected during the routine care of the tomato plants. Using this apparatus, we caught all whiteflies that invaded the non-guarded entrance door and minimized the appearance and spread of the viral disease in tomato plants in the greenhouse.

  15. Resistivity Problems in Electrostatic Precipitation

    ERIC Educational Resources Information Center

    White, Harry J.

    1974-01-01

    The process of electrostatic precipitation has ever-increasing application in more efficient collection of fine particles from industrial air emissions. This article details a large number of new developments in the field. The emphasis is on high resistivity particles which are a common cause of poor precipitator performance. (LS)

  16. Optimizing electrostatic field calculations with the Adaptive Poisson-Boltzmann Solver to predict electric fields at protein-protein interfaces II: explicit near-probe and hydrogen-bonding water molecules.

    PubMed

    Ritchie, Andrew W; Webb, Lauren J

    2014-07-17

    We have examined the effects of including explicit, near-probe solvent molecules in a continuum electrostatics strategy using the linear Poisson-Boltzmann equation with the Adaptive Poisson-Boltzmann Solver (APBS) to calculate electric fields at the midpoint of a nitrile bond both at the surface of a monomeric protein and when docked at a protein-protein interface. Results were compared to experimental vibrational absorption energy measurements of the nitrile oscillator. We examined three methods for selecting explicit water molecules: (1) all water molecules within 5 Å of the nitrile nitrogen; (2) the water molecule closest to the nitrile nitrogen; and (3) any single water molecule hydrogen-bonding to the nitrile. The correlation between absolute field strengths with experimental absorption energies were calculated and it was observed that method 1 was only an improvement for the monomer calculations, while methods 2 and 3 were not significantly different from the purely implicit solvent calculations for all protein systems examined. Upon taking the difference in calculated electrostatic fields and comparing to the difference in absorption frequencies, we typically observed an increase in experimental correlation for all methods, with method 1 showing the largest gain, likely due to the improved absolute monomer correlations using that method. These results suggest that, unlike with quantum mechanical methods, when calculating absolute fields using entirely classical models, implicit solvent is typically sufficient and additional work to identify hydrogen-bonding or nearest waters does not significantly impact the results. Although we observed that a sphere of solvent near the field of interest improved results for relative field calculations, it should not be consider a panacea for all situations.

  17. Effects of magnetic field on phase-mixing of electrostatic oscillations in cold electron-positron-ion plasmas

    NASA Astrophysics Data System (ADS)

    Pramanik, Sourav; Maity, Chandan

    2017-08-01

    Spatiotemporal evolution of nonlinear electron-positron oscillations around a homogeneous background of massive ions has been analyzed in cold electron-positron-ion (EPI) plasmas by employing a simple perturbation method, demonstrating phase-mixing and thus wave-breaking of excited oscillations at arbitrarily low amplitudes [C. Maity, Phys. Plasmas 21, 072317 (2014)]. In this work, we investigate effects of the magnetic field on the phase-mixing phenomena of electron-positron oscillations in cold EPI plasmas. A perturbative analysis of governing fluid-Maxwell's equations has been carried out up to third order to obtain a rough estimate of the phase-mixing time. It has been shown that the presence of an external ambient magnetic field may induce a delay in the process of phase-mixing of such oscillations.

  18. An analytical approach for scanning probe microscope-tip electrostatic field distribution accounting for dead layer and domain wall.

    PubMed

    Starkov, Alexander S; Starkov, Ivan A

    2013-12-01

    We have proposed a new theoretical approach for the determination of the electric field distribution in the ferroelectric/dielectric system with the presence of the SPM tip. The initial statement of the model has only a numerical solution. To find an analytical solution of the problem, some assumptions are introduced: the domain wall thickness can be considered to be much smaller than the domain size, and we use a high ferroelectric dielectric permittivity. The developed approach allows us to obtain explicit formulas for the polarization and electric field intensity. We have calculated and then analyzed the tip capacitance as a function of the distance from the ferroelectric interface. Additionally, different forms of the SPM tip are considered. It is demonstrated that in the presence of charges at the domain, the results differ from those obtained with the widely used dielectric model by 30%.

  19. Polarizable multipolar electrostatics for cholesterol

    NASA Astrophysics Data System (ADS)

    Fletcher, Timothy L.; Popelier, Paul L. A.

    2016-08-01

    FFLUX is a novel force field under development for biomolecular modelling, and is based on topological atoms and the machine learning method kriging. Successful kriging models have been obtained for realistic electrostatics of amino acids, small peptides, and some carbohydrates but here, for the first time, we construct kriging models for a sizeable ligand of great importance, which is cholesterol. Cholesterol's mean total (internal) electrostatic energy prediction error amounts to 3.9 kJ mol-1, which pleasingly falls below the threshold of 1 kcal mol-1 often cited for accurate biomolecular modelling. We present a detailed analysis of the error distributions.

  20. Surface electrostatics: theory and computations

    PubMed Central

    Chatzigeorgiou, G.; Javili, A.; Steinmann, P.

    2014-01-01

    The objective of this work is to study the electrostatic response of materials accounting for boundary surfaces with their own (electrostatic) constitutive behaviour. The electric response of materials with (electrostatic) energetic boundary surfaces (surfaces that possess material properties and constitutive structures different from those of the bulk) is formulated in a consistent manner using a variational framework. The forces and moments that appear due to bulk and surface electric fields are also expressed in a consistent manner. The theory is accompanied by numerical examples on porous materials using the finite-element method, where the influence of the surface electric permittivity on the electric displacement, the polarization stress and the Maxwell stress is examined. PMID:24711720

  1. Engineering scale electrostatic enclosure demonstration

    SciTech Connect

    Meyer, L.C.

    1993-09-01

    This report presents results from an engineering scale electrostatic enclosure demonstration test. The electrostatic enclosure is part of an overall in-depth contamination control strategy for transuranic (TRU) waste recovery operations. TRU contaminants include small particles of plutonium compounds associated with defense-related waste recovery operations. Demonstration test items consisted of an outer Perma-con enclosure, an inner tent enclosure, and a ventilation system test section for testing electrostatic curtain devices. Three interchangeable test fixtures that could remove plutonium from the contaminated dust were tested in the test section. These were an electret filter, a CRT as an electrostatic field source, and an electrically charged parallel plate separator. Enclosure materials tested included polyethylene, anti-static construction fabric, and stainless steel. The soil size distribution was determined using an eight stage cascade impactor. Photographs of particles containing plutonium were obtained with a scanning electron microscope (SEM). The SEM also provided a second method of getting the size distribution. The amount of plutonium removed from the aerosol by the electrostatic devices was determined by radiochemistry from input and output aerosol samplers. The inner and outer enclosures performed adequately for plutonium handling operations and could be used for full scale operations.

  2. PREFACE: Electrostatics 2015

    NASA Astrophysics Data System (ADS)

    Matthews, James

    2015-10-01

    Electrostatics 2015, supported by the Institute of Physics, was held in the Sir James Matthews building at Southampton Solent University, UK between 12th and 16th April 2015. Southampton is a historic city on the South Coast of England with a strong military and maritime history. Southampton is home to two Universities: Solent University, which hosted the conference, and the University of Southampton, where much work is undertaken related to electrostatics. 37 oral and 44 poster presentations were accepted for the conference, and 60 papers were submitted and accepted for the proceedings. The Bill Bright Memorial Lecture was delivered this year by Professor Mark Horenstein from Boston University who was, until recently, Editor-in-Chief of the Journal of Electrostatics. He spoke on The contribution of surface potential to diverse problems in electrostatics and his thorough knowledge of the subject of electrostatics was evident in the presentation. The first session was chaired by the Conference Chair, Dr Keith Davies, whose experience in the field showed through his frequent contributions to the discussions throughout the conference. Hazards and Electrostatic Discharge have formed a strong core to Electrostatics conferences for many years, and this conference contained sessions on both Hazards and on ESD, including an invited talk from Dr Jeremy Smallwood on ESD in Industry - Present and Future. Another strong theme to emerge from this year's programme was Non-Thermal Plasmas, which was covered in two sessions. There were two invited talks on this subject: Professor Masaaki Okubo gave a talk on Development of super-clean diesel engine and combustor using nonthermal plasma hybrid after treatment and Dr David Go presented a talk on Atmospheric-pressure ionization processes: New approaches and applications for plasmas in contact with liquids. A new innovation to the conference this year was the opportunity for conference sponsors to present to the delegates a technical

  3. Improvement of charged particles transport across a transverse magnetic filter field by electrostatic trapping of magnetized electrons

    SciTech Connect

    Das, B. K. Hazarika, P.; Chakraborty, M.; Bandyopadhyay, M.

    2014-07-15

    A study on the transport of charged particles across a magnetic filter field has been carried out in a double plasma device (DPD) and presented in this manuscript. The DPD is virtually divided into two parts viz. source and target regions by a transverse magnetic field (TMF) which is constructed by inserting strontium ferrite magnets into two stainless steel rectangular tubes. Plasma electrons are magnetized but ions are unmagnetized inside the TMF region. Negative voltages are applied to the TMF tubes in order to reduce the loss of electrons towards them. Plasma is produced in the source region by filament discharge method and allowed to flow towards the target region through this negatively biased TMF. It is observed that in the target region, plasma density can be increased and electron temperature decreased with the help of negatively biased TMF. This observation is beneficial for negative ion source development. Plasma diffusion across the negatively biased TMF follows Bohm or anomalous diffusion process when negative bias voltage is very less. At higher negative bias, diffusion coefficient starts deviating from the Bohm diffusion value, associated with enhanced plasma flow in the target region.

  4. Multi-point Analysis of Electrostatic Solitary Waves and Field Aligned Electrons Observed by Cluster in and Near the Auroral Current Regions

    NASA Astrophysics Data System (ADS)

    Pickett, J. S.; Forsyth, C.; Christopher, I.; Fazakerley, A. N.; Masson, A.; Marklund, G. T.; Georgescu, E.

    2011-12-01

    The four Cluster spacecraft have been transiting Earth's mid and upper auroral acceleration region (AAR) during parts of the year since late 2008. The Wideband Data (WBD) plasma wave receiver mounted on all four spacecraft obtains high time resolution, band-limited waveforms over a wide frequency range (100 Hz to 577 kHz). We present observations of Electrostatic Solitary Waves (ESWs) made by the WBD instrument simultaneously on more than one Cluster spacecraft in and near the auroral downward current region in the following two frequency bands: 100 Hz to 9.5 kHz and 700 Hz to 77 kHz. We examine and analyze these ESWs for similarities on different spacecraft, and investigate the conclusion, based on single spacecraft FAST satellite data, that fast ESWs (~1 ms duration) in this region are observed in conjunction with modulations in both upgoing and downgoing electrons, suggesting a current instability as the mechanism for generation of these ESWs. We also analyze and discuss the very short time duration ESWs (~20-30 microseconds) observed in the upward current region by the Cluster spacecraft. Such short time duration ESWs have not been previously reported in this region, although fast ESWs of ~300 microseconds duration have been reported using data from the FAST satellite. The Cluster PEACE electron data in this upward current region are examined to determine if there is a correlation of ESW detection with narrow, field-aligned downgoing beams as shown by the FAST results, suggesting ESW generation through a beam instability. The electron density and electric field data are also presented for some events in order to place the wave measurements into context with relation to the auroral density cavity and electric field configuration in and near the AAR.

  5. Direct coupling of thin-layer chromatography-bioautography with electrostatic field induced spray ionization-mass spectrometry for separation and identification of lipase inhibitors in lotus leaves.

    PubMed

    Zhang, Lei; Shi, Jiyao; Tang, Jihe; Cheng, Zhihong; Lu, Xiaohui; Kong, Yao; Wu, Tao

    2017-05-15

    In situ profiling compounds in complex matrices is important technology to develop in analytic chemistry. The aim of this study is to develop a direct coupling method of thin layer chromatography (TLC) to mass spectrometry (MS) via electrostatic field induced spray ionization (EFISI). We proposed a surface treatment method of normal-phase thin layer chromatography (TLC) plates with dimethyl silicone oil coating which successfully allowed TLC to couple to MS via EFISI. Different parameters affecting the ionization efficiency were investigated and optimized, including silicone oil concentrations, air-drying times, applied voltages, and TLC plate types. This optimized TLC-EFISI-MS method was successfully applied to examine lipase inhibitory components present in lotus leaves. Six active alkaloids including three aporphines and three benzylisoquinolines were profiled with their MS(n) (n = 4) data, or with a comparison with reference substances. This is the first report on the coupling EFISI-MS to TLC or TLC bioautography for in situ identification of active natural products. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Large Bi-Polar Signature in a Perpendicular Electric Field of Two-Dimensional Electrostatic Solitary Waves Associated with Magnetic Reconnection: Statistics and Discussion

    NASA Astrophysics Data System (ADS)

    Li, Shi-You; Zhang, Shi-Feng; Deng, Xiao-Hua; Cai, Hong

    2013-01-01

    More than 300 electrostatic solitary waves (ESWs) with a large perpendicular component which is a bi-polar waveform structure are observed in the boundary layer within the magnetic reconnection diffusion region in the near-Earth magnetotail. Such ESWs are called two-dimensional ESWs. A Singe-reconnection-based-statistical study of two-dimensional ESWs shows that: (1) ESWs can be continuously observed in the plasma sheet boundary layer (PSBL) associated with the magnetic reconnection diffusion region, and their amplitude ranges are mainly from several tens to hundreds of μV/m (2) both one-dimension-like ESWs (very small magnitude on E⊥) and two-dimension-like ESWs (large magnitude on E⊥, which are even comparable to that in the E‖) are observed within a small time interval; (3) within the observation time spans, more than 61% of ESWs are regarded as two-dimensional ESWs for the I2D > 20%. We discuss the bi-polar structure in E⊥. The observation of ESWs with a large bi-polar structure in the perpendicular electric field gives evidence that the unique waveform differs from previous understanding from observations and simulations which suggests that it should be a uni-polar waveform structure in the E⊥ of ESWs.

  7. Vertical phase separation of 6,13-bis(triisopropylsilylethynyl) pentacene/poly(methyl methacrylate) blends prepared by electrostatic spray deposition for organic field-effect transistors

    NASA Astrophysics Data System (ADS)

    Onojima, Norio; Hara, Kazuhiro; Nakamura, Ayato

    2017-05-01

    Blend films composed of 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS pentacene) and poly(methyl methacrylate) (PMMA) were prepared by electrostatic spray deposition (ESD). ESD is considered as an intermediate process between dry and wet processes since the solvent present in small droplets can almost be evaporated before arriving at the substrate. Post-drying treatments with the time-consuming evaporation of residual solvents can be omitted. However, it is still not clear that a vertically phase-separated structure can be formed in the ESD process since the vertical phase separation of the blend films is associated with the solvent evaporation. In this study, we fabricated bottom-gate, top-contact organic field-effect transistors based on the blend films prepared by ESD and the devices exhibited transistor behavior with small hysteresis. This result demonstrates that the vertical phase separation of a blend film (upper TIPS pentacene active layer/bottom PMMA gate insulator) can occur in the facile one-step ESD process.

  8. Electrostatic generator/motor configurations

    DOEpatents

    Post, Richard F

    2014-02-04

    Electrostatic generators/motors designs are provided that generally may include a first cylindrical stator centered about a longitudinal axis; a second cylindrical stator centered about the axis, a first cylindrical rotor centered about the axis and located between the first cylindrical stator and the second cylindrical stator. The first cylindrical stator, the second cylindrical stator and the first cylindrical rotor may be concentrically aligned. A magnetic field having field lines about parallel with the longitudinal axis is provided.

  9. Fine scale structure in the current sheet and electrostatic fields during driven magnetic reconnection on the VTF experiment.

    NASA Astrophysics Data System (ADS)

    Fox, William

    2005-10-01

    We have conducted a series of experiments in the VTF reconnection experiment[1] to measure with high resolution the current channel and electric structures that form in response to driven reconnection. Preliminary measurements have revealed that the current sheet is not symmetric across the X-line, contradicting an assumption fundamental to nearly every reconnection theory. Importantly, effects related to this asymmetry can account for momentum balance for the electrons at the X-line (i.e. fulfillment of the generalized Ohm's law) via convective inertia (m n v.∇v||). Measurements of strong in-plane electric field structures (E˜ 1 kV/m) near the X-point reveal a mechanism to efficiently heat ions, as has been recently observed by laser induced fluorescence (LIF) measurements of the ion distribution function[2].This work was supported by a DoE Fusion Energy Sciences Fellowship.[1] J. Egedal, et. al. (2001), Rev. Sci. Instrum. 71, 3351 [2] A. Stark, W. Fox, J.Egedal, O. Grulke, T. Klinger, (2005), submitted to Phys. Rev. Lett.

  10. Immediate Identification of Volcanic Eruption Intensity: Promising Test of a New Monitoring System Based on Short-Term Electrostatic Field Variations at the Active Volcano Popocatepetl, Mexico

    NASA Astrophysics Data System (ADS)

    Berger, P.

    2006-12-01

    Experiments by the Physikalisch Vulkanologisches Labor (PVL) in Wuerzburg, Germany, have shown that the intensity of violent volcanic eruptions, occurring when magma undergoes brittle fragmentation, is mirrored within brief electrical charges that can be detected on a short timescale (ms). Laboratory studies and certain explosion experiments offer the opportunity to calibrate the energy release of volcanic eruptions. Based on these results, a new high-precision, low-cost, real-time surveillance system is developed and tested at the active volcano of Popocatepetl, Mexico. This volcano, situated about 60 km southeast of Mexico City, offers excellent testing conditions, erupting regularly and intensively. The system, which detects short-term electrostatic field gradients (dc voltage against local ground), mainly consists of an antenna and a specially- designed amplifier. Depending on eruption intensity, as little as two or three eruptions will provide a sufficient amount of data. Amount, size, and shape of erupted particles give important indications about the physical fragmentation process which formed the pyroclasts, and hence about the type and intensity of the eruption. The evaluation and analysis of the samples collected at the volcano after each documented eruption will be carried out at the PVL. This physics lab, with a specially-designed experimental setup, allows controlled explosion experiments wherein rock from lava or bombs - related to the sampled pyroclasts - will be melted and subsequently brought to explosion. The energy released during these laboratory experiments will be calibrated to Popocatepetl using the ejecta volume of the observed eruptions, allowing a correlation of the actual energy release to the registered electrical field data. The aims of the project are: (1) quantification of individual magma properties of Popocatepetl (2) on-line measurement of mechanical energy release and mass flux and (3) immediate risk assessment of ongoing volcanic

  11. Miniature Electrostatic Ion Thruster With Magnet

    NASA Technical Reports Server (NTRS)

    Hartley, Frank T.

    2006-01-01

    A miniature electrostatic ion thruster is proposed that, with one exception, would be based on the same principles as those of the device described in the previous article, "Miniature Bipolar Electrostatic Ion Thruster". The exceptional feature of this thruster would be that, in addition to using electric fields for linear acceleration of ions and electrons, it would use a magnetic field to rotationally accelerate slow electrons into the ion stream to neutralize the ions.

  12. Electrostatic Levitator Electrodes

    NASA Technical Reports Server (NTRS)

    1998-01-01

    Electrostatic levitation system inside Electrostatic Levitator (ESL) vacuum chamber. The ESL uses static electricity to suspend an object (about 2-3 mm in diameter) inside a vacuum chamber while a laser heats the sample until it melts. This lets scientists record a wide range of physical properties without the sample contacting the container or any instruments, conditions that would alter the readings. The Electrostatic Levitator is one of several tools used in NASA's microgravity materials science program.

  13. Electrostatic Levitator Electrodes

    NASA Technical Reports Server (NTRS)

    1998-01-01

    Electrostatic levitation system inside Electrostatic Levitator (ESL) vacuum chamber. The ESL uses static electricity to suspend an object (about 2-3 mm in diameter) inside a vacuum chamber while a laser heats the sample until it melts. This lets scientists record a wide range of physical properties without the sample contacting the container or any instruments, conditions that would alter the readings. The Electrostatic Levitator is one of several tools used in NASA's microgravity materials science program.

  14. The Electrostatic Bell

    NASA Astrophysics Data System (ADS)

    Martrou, Guillaume; Leonetti, Marc

    2016-11-01

    An initially static fluid-fluid interface is known to become unstable under a strong electric field leading to jet instability, surface pattern and spout formation. Applying an electric field to an initial dripping mode accelerates the dripping rate and leads to a continuous jet mode. We show that those two different configurations, when applied to dielectric liquids, can lead to the same instability, the formation of an unexpected macroscopic fluid bell-shape of typical size few times the capillary length even if the needle is as small as 200 μm . The instability results from the competition between the dielectric and the gravity forces, reminiscent of the Taylor-Melcher mechanism. The study is performed on several fluids of various densities, permittivity and surface tension on a large range of electric field. We show that the transition is an imperfect subcritical bifurcation with its characteristic bottleneck effect (lag time). Finally, in the case of flow rate, we established a shape diagram with four domains corresponding to dripping, jetting, bridge and electrostatic bell.

  15. [Determination of fructo-oligosaccharides in milk powder by high performance liquid chromatography-quadrupole/electrostatic field orbitrap high resolution mass spectrometry].

    PubMed

    Liu, Yun; Ding, Tao; Xu, Suli; Wu, Bin; Shen, Chongyu; Zhang, Rui; Wang, Yan; Fei, Xiaoqing

    2015-10-01

    A method of high performance liquid chromatography-quadrupole/electrostatic field Orbitrap high resolution mass spectrometry (HPLC-Q/Orbitrap MS) was developed to determine fructo-oligosaccharides in milk powder. The milk powder samples were dissolved in deionized water. Subsequently, an aqueous solution of zinc acetate was used to precipitate protein. After centrifugation, the final aqueous solution was filtered by a polytetrafluoroethylene (PTFE) membrane with pore size of 0.22 μm. The analytes were separated on a Carbohydrate column (100 mm x 2.1 mm, 2.6 μm) through gradient elution with the combination of acetonitrile and 0.1% formic acid aqueous solution. The target-MS/MS templates were performed at isolation window of m/z 4.0 and collision energy of 30 eV in positive mode to extract the accurate product ion mass of analytes. Under the optimal condition, 1-kestose (GF2), nystose (GF3) and 1-F-β-fructofuranosyl nystose (GF4) were well separated and the accuracy of extracted mass routinely detected was below 5 x 10(-6) (5 ppm). The whole analysis time is only ten minutes. The detection limits for GF2 and GF3 were 100 μg/kg, and the detection limit for GF4 was 55 μg/kg. Good linearities were obtained in their respective linear ranges with correlation coefficients higher than 0.998. The average recoveries at three spiked levels (5, 10 and 20 mg/kg) were in the range of 75.8%-107.3% and the relative standard deviations (RSDs) were in the range of 1.6% - 8.3%. The proposed method is simple, sensitive, fast and only in need of precipitation of proteins. The interference of matrix can be eliminated through the selection of product ion. The results were convenient and reliable and thus can be used in the large batch determination of any milk powder.

  16. Hydrophobic and electrostatic interaction chromatography for estimating changes in cell surface charge of Escherichia coli cells treated with pulsed electric fields.

    PubMed

    Ukuku, Dike O; Yuk, Hyun-Gyun; Zhang, Howard

    2011-10-01

    Pulsed electric field (PEF) treatments, a nonthermal process, have been reported to injure and inactivate bacteria in liquid foods. However, the effect of this treatment on bacterial cell surface charge and hydrophobicity has not been investigated. Apple juice (pH 3.8) purchased from a wholesale distributor was inoculated with cocktail of Escherichia coli O157:H7 at 7.4 log CFU/mL, processed with a PEF at a field strength of 18.4 kV/cm and 32.2 kV/cm at 25°C, 35°C, and 45°C with a treatment time of 160 μs and a flow rate of 120 mL/min. Bacterial cell surface charge and hydrophobicity of untreated and PEF-treated E. coli O157:H7 were determined immediately and after storage at 5°C and 23°C using hydrophobic and electrostatic interaction chromatography. Similarly, the populations surviving the PEF treatments including injured cells were determined by plating 0.1 mL of the sample on sorbitol MacConkey agar and tryptic soy agar (TSA) plates. The surviving populations of E. coli cells after PEF treatment varied depending on field strength and treatment temperature used. Percent injury in the surviving populations was high immediately after PEF treatment and varied among treatment temperatures. Cell surface charge of E. coli bacteria before PEF treatment averaged 32.10±8.12. PEF treatments at 25°C, 35°C, and 45°C reduced the above surface charge to 26.34±1.24, 14.24±3.30, and 6.72±2.82, respectively. Similarly, the surface hydrophobicity of untreated E. coli cells at 0.194±0.034 was increased to an average of 0.268±0.022, 0.320±0.124, and 0.586±0.123 after PEF treatments at 25°C, 35°C, and 45°C, respectively. The results of this study indicate that PEF treatment affects the outer cell envelope of E. coli bacteria as evidenced by the changes in surface hydrophobicity and cell surface charge leading to injury and subsequent inactivation of the cells.

  17. Electrostatic forces for personnel restraints

    NASA Technical Reports Server (NTRS)

    Ashby, N.; Ciciora, J.; Gardner, R.; Porter, K.

    1977-01-01

    The feasibility of utilizing electrostatic forces for personnel retention devices on exterior spacecraft surfaces was analyzed. The investigation covered: (1) determination of the state of the art; (2) analysis of potential adhesion surfaces; (3) safety considerations for personnel; (4) electromagnetic force field determination and its effect on spacecraft instrumentation; and (5) proposed advances to current technology based on documentation review, analyses, and experimental test data.

  18. Edutainment Science: Electrostatics

    ERIC Educational Resources Information Center

    Ahlers, Carl

    2009-01-01

    Electrostatics should find a special place in all primary school science curricula. It is a great learning area that reinforces the basics that underpin electricity and atomic structure. Furthermore, it has many well documented hands-on activities. Unfortunately, the "traditional" electrostatics equipment such as PVC rods, woollen cloths, rabbit…

  19. Electrostatic Levitator (ESL)

    NASA Technical Reports Server (NTRS)

    1998-01-01

    Dr. Rulison of Space System LORAl working with the Electrostatic Levitation (ESL) prior to the donation. Space System/LORAL donated the electrostatic containerless processing system to NASA's Marshall Space Flight Center (MSFC). The official hand over took place in July 1998.

  20. Edutainment Science: Electrostatics

    ERIC Educational Resources Information Center

    Ahlers, Carl

    2009-01-01

    Electrostatics should find a special place in all primary school science curricula. It is a great learning area that reinforces the basics that underpin electricity and atomic structure. Furthermore, it has many well documented hands-on activities. Unfortunately, the "traditional" electrostatics equipment such as PVC rods, woollen cloths, rabbit…

  1. Hantavirus cardiopulmonary syndrome successfully treated with high-volume hemofiltration

    PubMed Central

    Bugedo, Guillermo; Florez, Jorge; Ferres, Marcela; Roessler, Eric; Bruhn, Alejandro

    2016-01-01

    Hantavirus cardiopulmonary syndrome has a high mortality rate, and early connection to extracorporeal membrane oxygenation has been suggested to improve outcomes. We report the case of a patient with demonstrated Hantavirus cardiopulmonary syndrome and refractory shock who fulfilled the criteria for extracorporeal membrane oxygenation and responded successfully to high volume continuous hemofiltration. The implementation of high volume continuous hemofiltration along with protective ventilation reversed the shock within a few hours and may have prompted recovery. In patients with Hantavirus cardiopulmonary syndrome, a short course of high volume continuous hemofiltration may help differentiate patients who can be treated with conventional intensive care unit management from those who will require more complex therapies, such as extracorporeal membrane oxygenation. PMID:27410413

  2. Electrostatic-free piezoresponse force microscopy

    PubMed Central

    Kim, Sungho; Seol, Daehee; Lu, Xiaoli; Alexe, Marin; Kim, Yunseok

    2017-01-01

    Contact and non-contact based atomic force microscopy (AFM) approaches have been extensively utilized to explore various nanoscale surface properties. In most AFM-based measurements, a concurrent electrostatic effect between the AFM tip/cantilever and sample surface can occur. This electrostatic effect often hinders accurate measurements. Thus, it is very important to quantify as well as remove the impact of the electrostatic effect on AFM-based measurements. In this study, we examine the impact of the electrostatic effect on the electromechanical (EM) response in piezoresponse force microscopy as a model AFM mode. We quantitatively studied the effects of increasing the external electric field and reducing the spring constant of a cantilever. Further, we explored ways to minimize the electrostatic effect. The results provide broad guidelines for quantitatively analyzing the EM response as well as, eventually, for obtaining the electrostatic-free EM response. The conclusions can be applied to other AFM-based measurements that are subject to a strong electrostatic effect between the AFM tip/cantilever and sample surface, regardless of contact and non-contact modes. PMID:28139715

  3. Electrostatic-free piezoresponse force microscopy

    NASA Astrophysics Data System (ADS)

    Kim, Sungho; Seol, Daehee; Lu, Xiaoli; Alexe, Marin; Kim, Yunseok

    2017-01-01

    Contact and non-contact based atomic force microscopy (AFM) approaches have been extensively utilized to explore various nanoscale surface properties. In most AFM-based measurements, a concurrent electrostatic effect between the AFM tip/cantilever and sample surface can occur. This electrostatic effect often hinders accurate measurements. Thus, it is very important to quantify as well as remove the impact of the electrostatic effect on AFM-based measurements. In this study, we examine the impact of the electrostatic effect on the electromechanical (EM) response in piezoresponse force microscopy as a model AFM mode. We quantitatively studied the effects of increasing the external electric field and reducing the spring constant of a cantilever. Further, we explored ways to minimize the electrostatic effect. The results provide broad guidelines for quantitatively analyzing the EM response as well as, eventually, for obtaining the electrostatic-free EM response. The conclusions can be applied to other AFM-based measurements that are subject to a strong electrostatic effect between the AFM tip/cantilever and sample surface, regardless of contact and non-contact modes.

  4. Intrinsic electrostatic effects in nanostructured ceramics

    SciTech Connect

    Uberuaga, Blas Pedro; Stanek, Chris R; Nerikar, Pankaj V

    2009-01-01

    Using empirical potentials, we have found that electrostatic dipoles can be created at grain boundaries formed from non-polar surfaces of fluorite-structured materials. In particular, the {Sigma}5(310)/[001] symmetric tilt grain boundary reconstructs to break the symmetry in the atomic structure at the boundary, forming the dipole. This dipole results in an abrupt change in electrostatic potential across the boundary. In multilayered ceramics composed of stacks of grain boundaries, the change in electrostatic potential at the boundary results in profound electrostatic effects within the crystalline layers, the nature of which depends on the electrostatic boundary conditions. For open-circuit boundary conditions, layers with either high or low electrostatic potential are formed. By contrast, for short-circuit boundary conditions, electric fields can be created within each layer, the strength of which then depends on the thickness of the layers. These electrostatic effects may have important consequences for the behavior of defects and dopants within these materials and offer the possibility of interesting technological applications.

  5. Electrostatic Spraying With Conductive Liquids

    NASA Technical Reports Server (NTRS)

    Kosmo, Joseph J.; Dawn, Frederic S.; Erlandson, Robert E.; Atkins, Loren E.

    1989-01-01

    Thin, uniform polymer coatings applied in water base normally impossible to charge. Electrostatic sprayer modified so applies coatings suspended or dissolved in electrically conductive liquids. Nozzle and gun constructed of nonconductive molded plastic. Liquid passageway made long enough electrical leakage through it low. Coaxial hose for liquid built of polytetrafluoroethylene tube, insulating sleeve, and polyurethane jacket. Sprayer provided with insulated seal at gun-to-hose connection, nonconductive airhose, pressure tank electrically isolated from ground, and special nozzle electrode. Supply of atomizing air reduced so particle momentum controlled by electrostatic field more effectively. Developed to apply water-base polyurethane coating to woven, shaped polyester fabric. Coating provides pressure seal for fabric, which is part of spacesuit. Also useful for applying waterproof, decorative, or protective coatings to fabrics for use on Earth.

  6. Closed loop electrostatic levitation system

    NASA Technical Reports Server (NTRS)

    Rhim, W. K.; Saffren, M. M.; Elleman, D. D. (Inventor)

    1985-01-01

    An electrostatic levitation system is described, which can closely control the position of objects of appreciable size. A plurality of electrodes surround the desired position of an electrostatically charged object, the position of the objects is monitored, and the voltages applied to the electrodes are varied to hold the object at a desired position. In one system, the object is suspended above a plate-like electrode which has a concave upper face to urge the object toward the vertical axis of the curved plate. An upper electrode that is also curved can be positioned above the object, to assure curvature of the field at any height above the lower plate. In another system, four spherical electrodes are positioned at the points of a tetrahedron, and the voltages applied to the electrodes are varied in accordance with the object position as detected by two sensors.

  7. Asteroid electrostatic instrumentation and modelling

    NASA Astrophysics Data System (ADS)

    Aplin, K. L.; Bowles, N. E.; Urbak, E.; Keane, D.; Sawyer, E. C.

    2011-06-01

    Asteroid surface material is expected to become photoelectrically charged, and is likely to be transported through electrostatic levitation. Understanding any movement of the surface material is relevant to proposed space missions to return samples to Earth for detailed isotopic analysis. Motivated by preparations for the Marco Polo sample return mission, we present electrostatic modelling for a real asteroid, Itokawa, for which detailed shape information is available, and verify that charging effects are likely to be significant at the terminator and at the edges of shadow regions for the Marco Polo baseline asteroid, 1999JU3. We also describe the Asteroid Charge Experiment electric field instrumentation intended for Marco Polo. Finally, we find that the differing asteroid and spacecraft potentials on landing could perturb sample collection for the short landing time of 20min that is currently planned.

  8. Electrostatic Gating of Ultrathin Films

    NASA Astrophysics Data System (ADS)

    Goldman, A. M.

    2014-07-01

    Electrostatic gating of ultrathin films can be used to modify electronic and magnetic properties of materials by effecting controlled alterations of carrier concentration while, in principle, not changing the level of disorder. As such, electrostatic gating can facilitate the development of novel devices and can serve as a means of exploring the fundamental properties of materials in a manner far simpler than is possible with the conventional approach of chemical doping. The entire phase diagram of a compound can be traversed by changing the gate voltage. In this review, we survey results involving conventional field effect devices as well as more recent progress, which has involved structures that rely on electrochemical configurations such as electric double-layer transistors. We emphasize progress involving thin films of oxide materials such as high-temperature superconductors, magnetic oxides, and oxides that undergo metal-insulator transitions.

  9. Electrostatic Spraying With Conductive Liquids

    NASA Technical Reports Server (NTRS)

    Kosmo, Joseph J.; Dawn, Frederic S.; Erlandson, Robert E.; Atkins, Loren E.

    1989-01-01

    Thin, uniform polymer coatings applied in water base normally impossible to charge. Electrostatic sprayer modified so applies coatings suspended or dissolved in electrically conductive liquids. Nozzle and gun constructed of nonconductive molded plastic. Liquid passageway made long enough electrical leakage through it low. Coaxial hose for liquid built of polytetrafluoroethylene tube, insulating sleeve, and polyurethane jacket. Sprayer provided with insulated seal at gun-to-hose connection, nonconductive airhose, pressure tank electrically isolated from ground, and special nozzle electrode. Supply of atomizing air reduced so particle momentum controlled by electrostatic field more effectively. Developed to apply water-base polyurethane coating to woven, shaped polyester fabric. Coating provides pressure seal for fabric, which is part of spacesuit. Also useful for applying waterproof, decorative, or protective coatings to fabrics for use on Earth.

  10. The electrostatic storage tube

    NASA Technical Reports Server (NTRS)

    Rutherford, R. E., Jr.

    1973-01-01

    An electrostatic camera system is discussed which is based on the electrostatic storage tube. The development of the system was begun following a series of experiments which indicated that the device offers signficantly improved performance over currently available devices. The approach used in developing the high performance camera involves: converting the input image to an electron image at low loss, applying a low noise gain process, and storing the resulting charge pattern in a low-loss target. The basic processes and elements of the electrostatic storage tube are illustrated and discussed. Graphs that depict the camera performance characteristics are included.

  11. Electrostatic drops in orbit

    NASA Astrophysics Data System (ADS)

    Rodriguez, Isabel J.; Schmidt, Erin; Weislogel, Mark M.; Pettit, Donald

    2016-11-01

    We present what we think are the first intentional electrostatic orbits in the near-weightless environment of a drop tower. Classical physics problems involving Coulombic forces in orbital mechanics have traditionally been confined to thought experiments due to practical terrestrial experimental limitations, namely, the preponderance of gravity. However, the use of a drop tower as an experimental platform can overcome this challenge for brief periods. We demonstrate methanol-water droplets in orbit around a variety of charged objects- some of which can be used to validate special cases of N-body systems. Footage collected via a high-speed camera is analyzed and orbital trajectories are compared with existing theoretical predictions. Droplets of diameters 0.5 to 2mm in a variety of obits are observed. Due to the repeatability of drop tower initial conditions and effective low-g environment, such experiments may be used to construct empirical analogues and confirm analyses toward the benefit of other fields including space and planetary science. NASA Cooperative Agreement NNX12A047A, Portland State LSAMP, Robert E. McNair Scholars Program.

  12. Electrostatic particle trap for ion beam sputter deposition

    DOEpatents

    Vernon, Stephen P.; Burkhart, Scott C.

    2002-01-01

    A method and apparatus for the interception and trapping of or reflection of charged particulate matter generated in ion beam sputter deposition. The apparatus involves an electrostatic particle trap which generates electrostatic fields in the vicinity of the substrate on which target material is being deposited. The electrostatic particle trap consists of an array of electrode surfaces, each maintained at an electrostatic potential, and with their surfaces parallel or perpendicular to the surface of the substrate. The method involves interception and trapping of or reflection of charged particles achieved by generating electrostatic fields in the vicinity of the substrate, and configuring the fields to force the charged particulate material away from the substrate. The electrostatic charged particle trap enables prevention of charged particles from being deposited on the substrate thereby enabling the deposition of extremely low defect density films, such as required for reflective masks of an extreme ultraviolet lithography (EUVL) system.

  13. Micromachined electrostatic vertical actuator

    SciTech Connect

    Lee, A.P.; Sommargren, G.E.; McConaghy, C.F.; Krulevitch, P.A.

    1999-10-19

    A micromachined vertical actuator utilizing a levitational force, such as in electrostatic comb drives, provides vertical actuation that is relatively linear in actuation for control, and can be readily combined with parallel plate capacitive position sensing for position control. The micromachined electrostatic vertical actuator provides accurate movement in the sub-micron to micron ranges which is desirable in the phase modulation instrument, such as optical phase shifting. For example, compact, inexpensive, and position controllable micromirrors utilizing an electrostatic vertical actuator can replace the large, expensive, and difficult-to-maintain piezoelectric actuators. A thirty pound piezoelectric actuator with corner cube reflectors, as utilized in a phase shifting diffraction interferometer can be replaced with a micromirror and a lens. For any very precise and small amplitudes of motion, micromachined electrostatic actuation may be used because it is the most compact in size, with low power consumption and has more straightforward sensing and control options.

  14. More Electrostatic Explorations.

    ERIC Educational Resources Information Center

    Stewart, Gay; Gallai, Ditta

    1998-01-01

    Presents worksheet activities that enable students to explore the concept of electrostatic induction and learn the meaning of grounding. Students build two classic devices, the electrophorus and the leaf electroscope. (DDR)

  15. More Electrostatic Explorations.

    ERIC Educational Resources Information Center

    Stewart, Gay; Gallai, Ditta

    1998-01-01

    Presents worksheet activities that enable students to explore the concept of electrostatic induction and learn the meaning of grounding. Students build two classic devices, the electrophorus and the leaf electroscope. (DDR)

  16. Micromachined electrostatic vertical actuator

    DOEpatents

    Lee, Abraham P.; Sommargren, Gary E.; McConaghy, Charles F.; Krulevitch, Peter A.

    1999-10-19

    A micromachined vertical actuator utilizing a levitational force, such as in electrostatic comb drives, provides vertical actuation that is relatively linear in actuation for control, and can be readily combined with parallel plate capacitive position sensing for position control. The micromachined electrostatic vertical actuator provides accurate movement in the sub-micron to micron ranges which is desirable in the phase modulation instrument, such as optical phase shifting. For example, compact, inexpensive, and position controllable micromirrors utilizing an electrostatic vertical actuator can replace the large, expensive, and difficult-to-maintain piezoelectric actuators. A thirty pound piezoelectric actuator with corner cube reflectors, as utilized in a phase shifting diffraction interferometer can be replaced with a micromirror and a lens. For any very precise and small amplitudes of motion` micromachined electrostatic actuation may be used because it is the most compact in size, with low power consumption and has more straightforward sensing and control options.

  17. Electrostatic correlations near charged planar surfaces

    PubMed Central

    Deng, Mingge; Em Karniadakis, George

    2014-01-01

    Electrostatic correlation effects near charged planar surfaces immersed in a symmetric electrolytes solution are systematically studied by numerically solving the nonlinear six-dimensional electrostatic self-consistent equations. We compare our numerical results with widely accepted mean-field (MF) theory results, and find that the MF theory remains quantitatively accurate only in weakly charged regimes, whereas in strongly charged regimes, the MF predictions deviate drastically due to the electrostatic correlation effects. We also observe a first-order like phase-transition corresponding to the counterion condensation phenomenon in strongly charged regimes, and compute the phase diagram numerically within a wide parameter range. Finally, we investigate the interactions between two likely-charged planar surfaces, which repulse each other as MF theory predicts in weakly charged regimes. However, our results show that they attract each other above a certain distance in strongly charged regimes due to significant electrostatic correlations. PMID:25194382

  18. Interpretation and Prediction of Molecular Reactivities and Design of Synthetic Pathways, Using Electrostatic Potentials, Electric Fields and Other Properties Related to Charge Density Distribution

    DTIC Science & Technology

    1988-10-07

    J. M. Seminario and P. Politzer, "Z Transition State Calculations of Energy Changes and Electrostatic Potentials in Isoelectronic Atoms and Molecules...Potentials in Isoelectronic Atoms and Molecules" K. D. Sen, J. M. Seminario and P. Politzer, submitted to Journal of Chemical Physics. (16) "Characteristic...M. Elminyawi Dr. Keerthi Jayasuriya Dr. Gary P. Kirschenheuter Mrs. Pat Lane Dr. Jane S. Murray Dr. Jorge M. Seminario Dr. K. D. Sen Mr. Per Sjoberg

  19. Electrostatic discharge test apparatus

    NASA Technical Reports Server (NTRS)

    Smith, William C. (Inventor)

    1989-01-01

    Electrostatic discharge properties of materials are quantitatively measured and ranked. Samples (20) are rotated on a turntable (15) beneath selectable, co-available electrostatic chargers (30/40), one being a corona charging element (30) and the other a sample-engaging triboelectric charging element (40). They then pass under a voltage meter (25) to measure the amount of residual charge on the samples (20). After charging is discontinued, measurements are continued to record the charge decay history over time.

  20. Electrostatic discharge test apparatus

    NASA Technical Reports Server (NTRS)

    Smith, William Conrad (Inventor)

    1988-01-01

    Electrostatic discharge properties of materials are quantitatively measured and ranked. Samples are rotated on a turntable beneath selectable, co-available electrostatic chargers, one being a corona charging element and the other a sample-engaging triboelectric charging element. Samples then pass under a voltage meter to measure the amount of residual charge on the samples. After charging is discontinued, measurements are continued to record the charge decay history over time.

  1. Electrostatic Levitator Electrode Layout

    NASA Technical Reports Server (NTRS)

    1998-01-01

    Schematic of Electrostatic Levitator (ESL) electrodes and controls system. The ESL uses static electricity to suspend an object (about 2-3 mm in diameter) inside a vacuum chamber while a laser heats the sample until it melts. This lets scientists record a wide range of physical properties without the sample contacting the container or any instruments, conditions that would alter the readings. The Electrostatic Levitator is one of several tools used in NASA's microgravity materials science program.

  2. Electrostatic Linear Actuator

    NASA Technical Reports Server (NTRS)

    Collins, Earl R., Jr.; Curry, Kenneth C.

    1990-01-01

    Electrically charged helices attract or repel each other. Proposed electrostatic linear actuator made with intertwined dual helices, which holds charge-bearing surfaces. Dual-helix configuration provides relatively large unbroken facing charged surfaces (relatively large electrostatic force) within small volume. Inner helix slides axially in outer helix in response to voltages applied to conductors. Spiral form also makes components more rigid. Actuator conceived to have few moving parts and to be operable after long intervals of inactivity.

  3. Graphene Electrostatic Microphone

    NASA Astrophysics Data System (ADS)

    Zhou, Qin; Onishi, Seita; Zettl, A.

    2015-03-01

    We demonstrate a wideband electrostatic graphene microphone displaying flat frequency response over the entire human audible region as well as into the ultrasonic regime. Using the microphone, low-level ultrasonic bat calls are successfully recorded. The microphone can be paired with a similarly constructed electrostatic graphene loudspeaker to create a wideband ultrasonic radio. Materials Sciences Division, Lawrence Berkeley National Laboratory Kavli Energy NanoSciences Institute at the University of California - Berkeley.

  4. Electrostatic Levitator in Use

    NASA Technical Reports Server (NTRS)

    1998-01-01

    Metal droplet levitated inside the Electrostatic Levitator (ESL). The ESL uses static electricity to suspend an object (about 2-3 mm in diameter) inside a vacuum chamber while a laser heats the sample until it melts. This lets scientists record a wide range of physical properties without the sample contacting the container or any instruments, conditions that would alter the readings. The Electrostatic Levitator is one of several tools used in NASA's microgravity materials science program.

  5. Electrostatic Levitator Electrode Layout

    NASA Technical Reports Server (NTRS)

    1998-01-01

    Schematic of Electrostatic Levitator (ESL) electrodes and controls system. The ESL uses static electricity to suspend an object (about 2-3 mm in diameter) inside a vacuum chamber while a laser heats the sample until it melts. This lets scientists record a wide range of physical properties without the sample contacting the container or any instruments, conditions that would alter the readings. The Electrostatic Levitator is one of several tools used in NASA's microgravity materials science program.

  6. Electrostatic Levitator Layout

    NASA Technical Reports Server (NTRS)

    1998-01-01

    General oayout of Electrostatic Levitator (ESL). The ESL uses static electricity to suspend an object (about 2-3 mm in diameter) inside a vacuum chamber while a laser heats the sample until it melts. This lets scientists record a wide range of physical properties without the sample contacting the container or any instruments, conditions that would alter the readings. The Electrostatic Levitator is one of several tools used in NASA's microgravity materials science program.

  7. Voltage limitations of electrostatic accelerators

    SciTech Connect

    Hyder, H.R. )

    1999-04-01

    The history of electrostatic accelerators has been punctuated by a series of projects in which innovative designs have failed to meet the expectations of their designers. From the early, air-insulated Van de Graaffs at Round Hill to certain of the large pressurized heavy ion accelerators of the 1970s and 1980s, increases in size or changes in design and materials have not always led to the maximum voltages expected or extrapolated. Since these failures have continued beyond childhood into a mature technology, it is reasonable to assume that the causes of voltage limitation are varied and complex. They have remained poorly understood for a number of reasons: resources for an extended program of research into breakdown and failure of electrostatic generators have always been meager, especially for large machines devoted to nuclear research; the inaccessibility of pressurized generators makes instrumentation difficult and testing slow; the calculation of transient and dynamic effects is laborious and the results difficult to verify; voltage test experiments on operating accelerators are inhibited by the significant risk of damage due to energy release on breakdown: and the total voltages (though not the local fields) achieved in many electrostatic accelerators exceed those produced in any other man-made environment. In this review, the behavior of several generators of different designs is examined in order to assess the importance of the various design features and operating conditions that control the maximum voltage achievable in a working machine. [copyright] [ital 1999 American Institute of Physics.

  8. Electrostatic effects in DNA stretching

    NASA Astrophysics Data System (ADS)

    Tkachenko, Alexei V.

    2006-10-01

    The response of a semiflexible polyelectrolyte chain to stretching in the regimes of moderate and weak screening is studied theoretically, with a special focus on DNA experiments. By using the nonlinear Poisson-Boltzmann description of electrostatic self-interactions of the chain, we explicitly demonstrate the applicability of the concept of effective charge to certain aspects of the problem. This charge can be extracted from the far-field asymptotic behavior of the electrostatic potential of the fully aligned chain. Surprisingly, in terms of the effective charge, the electrostatically renormalized persistence length can be formally described by the classical Odijk-Skolnick-Fixman formula, whose domain of applicability is normally limited to the linearized Debye-Hückel (DH) approximation. However, the short-scale behavior of the chain in the nonlinear regime deviates from the of DH-based result, even upon charge renormalization. This difference is revealed in the calculated stretching curves for strongly charged DNA. These results are in good agreement with recent experiments. In the limit of weak screening we predict the elastic response to have a distinctive two-stage character, with a peculiar intermediate “unstretchable” regime.

  9. Monitoring Mars for Electrostatic Disturbances

    NASA Technical Reports Server (NTRS)

    Compton, D.

    2011-01-01

    The DSN radio telescope DSS-13 was used to monitor Mars for electrostatic discharges from 17 February to 11 April, 2010, and from 19 April to 4 May, 2011, over a total of 72 sessions. Of these sessions, few showed noteworthy results and no outstanding electrostatic disturbances were observed on Mars from analyzing the kurtosis of radio emission from Mars. Electrostatic discharges on mars were originally detected in June of 2006 by Ruf et al. using DSS-13. he kurtosis (normalized fourth moment of the electrical field strength) is sensitive to non-thermal radiation. Two frequencies bands, either 2.4 and 8.4 GHz or 8.4 and 32 GHz were used. The non-thermal radiation spectrum should have peaks at the lowest three modes of the theoretical Schumann Resonances of Mars. The telescope was pointed away from Mars every 5 minutes for 45 seconds to confirm if Mars was indeed the sources of any events. It was shown that by including a down-link signal in one channel and by observing when the kurtosis changed as the telescope was pointed away from the source that the procedure can monitor Mars without the need of extra equipment monitoring a control source.

  10. Electrostatic fuel conditioning of internal combustion engines

    NASA Technical Reports Server (NTRS)

    Gold, P. I.

    1982-01-01

    Diesel engines were tested to determine if they are influenced by the presence of electrostatic and magnetic fields. Field forces were applied in a variety of configurations including pretreatment of the fuel and air, however, no affect on engine performance was observed.

  11. Investigation on particle flow characteristics using electrostatic sensor array

    NASA Astrophysics Data System (ADS)

    Fu, Feifei; Xu, Chuanlong; Heming, Gao, Jian, Li; Wang, Shimin

    2012-03-01

    In recent years, great advance has been made on electrostatic sensing technique for gas-solid flow measurement. Electrostatic tomography(EST) has been used in experiment researches as a novel non-intrusive measurement technique. Electrostatic sensor array is one of the key parts of electrostatic tomography system. Based on the image reconstruction algorithm, the charge on the particles can be obtained from the electrostatic measurement signals. However, reports on the relationship between the electrostatic signal acquired by the electrostatic sensor array and flow characteristics of the particles were very few. In this paper the mathematical model of the electrostatic sensor array was adopted, and its spatial sensitivity field was investigated. In the experiment, the electrostatic signals of the quarter flow and full pipe flow were acquired by the electrostatic sensor array. Based on the EST experiment and Power Spectrum Analysis of Signal, the energy distributions of those two flow patterns were compared. Results show that the sensitivity of the electrostatic sensor array is inhomogeneous in three-dimensional space. For this reason, the energy distributions of those two flow patterns are distinguished.

  12. Development of high volume rice husk ash alumino silicate composites

    NASA Astrophysics Data System (ADS)

    Rattanasak, Ubolluk; Chindaprasirt, Prinya; Suwanvitaya, Prasert

    2010-10-01

    The development of high volume rice husk ash (RHA) alumino silicate composites (ASC) was studied. RHA was used as the source of silica and aluminium in the ASC. The mass ratios of RHA:Al(OH)3 of 70:30 to 99:1 were tested. The results indicate that the obtained ASC mortars are not stable and disintegrate in water. Boric acid was introduced to the mixture to overcome this problem. Stable ASC mortars with high RHA:Al(OH)3 mass ratios of 90:10 to 97.5:2.5 were obtained with the use of boric acid and 115°C curing. The compressive strength of the mortar of 20 MPa was gained. The immersion test indicates that high volume RHA ASC mortars show good resistance in 3vol% H2SO4 solution, but is slightly less durable in 5wt% MgSO4 solution.

  13. Integration of smart materials into high-volume manufacturing methods

    NASA Astrophysics Data System (ADS)

    Bianchini, Emanuele

    2006-03-01

    The integration of smart materials such as piezoelectric devices and shape memory alloys into structures has been typically limited to a bonding process that occurs as a secondary operation. Such an operation is not only costly for high volume applications but also has the potential of degrading the performance of the actuator or sensor due to the bonding agent selected. The work presented here explores the integration of piezoelectric materials using a high volume injection molding process. The process used is typical for large automotive components such as bumpers, instrument panels and other body panels. Different materials were evaluated, including plastics and both bare and packaged smart materials. Temperature and flow rate were also changed to investigate the effects on the durability of the materials. Both electrical and mechanical properties were tested with the key parameters including, void content, shifting from initial position, strain transfer and peal strength. It was found that good integration of piezoelectric materials could be achieved and electro-mechanical properties were improved as compared to a secondary bonding operation. Integration of screen-printed electrical circuits for electrical connectivity for piezoelectric materials will be evaluated in future research. In conclusion, a step forward was made in developing a multifunctional material based upon smart materials and conventional high volume manufacturing processes.

  14. Why choose high volume online post-dilution hemodiafiltration?

    PubMed

    Basile, Carlo; Davenport, Andrew; Blankestijn, Peter J

    2017-04-01

    The mortality rate of patients on maintenance dialysis remains alarmingly high, at approximately 15-20 % per year. Increasing dialyzer urea clearance has not been shown to improve survival and hence interest has shifted towards convective therapies, such as hemodiafiltration (HDF) which can remove middle molecular weight uremic toxins, which have been suggested to increase mortality in patients with end-stage kidney disease. During the last few years, four large prospective randomized controlled trials (RCTs) have been conducted in different European countries to compare survival outcomes in prevalent patients receiving conventional hemodialysis with online post-dilution HDF (OL HDF). Furthermore, a pooled individual participant data analysis from four RCTs was performed and four large meta-analyses on convective therapies have been published in the last 2 years. Taken together, these studies support the conclusion that high volume post-dilution OL HDF is associated with improved overall survival. This advantage results predominantly from a lower cardiovascular mortality, possibly due to better preservation of left ventricle mass and function. Improved intra-dialytic blood pressure stability may contribute to the beneficial effect of high volume post-dilution OL HDF on survival. The beneficial effect is not restricted to selected subgroups, such as age, comorbidity or dialysis vintage. There is no compelling evidence that high volume post-dilution OL HDF reduces mortality by improvements in traditional and non-traditional risk factors. There are still no studies or case reports published describing adverse clinical outcomes in more than 20 years of HDF clinical experience. In conclusion, most of the available data support the choice of high volume post-dilution HDF over the current dialysis techniques. However, considering that we live in the era of evidence-based medicine, the evidence supporting the superiority of high volume post-dilution OL HDF in

  15. Large electrostatic accelerators

    SciTech Connect

    Jones, C.M.

    1984-01-01

    The increasing importance of energetic heavy ion beams in the study of atomic physics, nuclear physics, and materials science has partially or wholly motivated the construction of a new generation of large electrostatic accelerators designed to operate at terminal potentials of 20 MV or above. In this paper, the author briefly discusses the status of these new accelerators and also discusses several recent technological advances which may be expected to further improve their performance. The paper is divided into four parts: (1) a discussion of the motivation for the construction of large electrostatic accelerators, (2) a description and discussion of several large electrostatic accelerators which have been recently completed or are under construction, (3) a description of several recent innovations which may be expected to improve the performance of large electrostatic accelerators in the future, and (4) a description of an innovative new large electrostatic accelerator whose construction is scheduled to begin next year. Due to time and space constraints, discussion is restricted to consideration of only tandem accelerators.

  16. DEVELOPMENT AND EVALUATION OF A HIGH-VOLUME DICHOTOMOUS SAMPLER FOR CHEMICAL SPECIATION OF COARSE AND FINE PARTICLES

    EPA Science Inventory

    This paper describes the development and field evaluation of a compact high-volume dichotomous sampler (HVDS) that collects coarse (PM10-2.5) and fine (PM2.5) particulate matter. In its primary configuration as tested, the sampler size-fractionates PM10 into...

  17. DEVELOPMENT AND EVALUATION OF A HIGH-VOLUME DICHOTOMOUS SAMPLER FOR CHEMICAL SPECIATION OF COARSE AND FINE PARTICLES

    EPA Science Inventory

    This paper describes the development and field evaluation of a compact high-volume dichotomous sampler (HVDS) that collects coarse (PM10-2.5) and fine (PM2.5) particulate matter. In its primary configuration as tested, the sampler size-fractionates PM10 into...

  18. Electrostatic particle collection in vacuum

    NASA Astrophysics Data System (ADS)

    Afshar-Mohajer, Nima; Damit, Brian; Wu, Chang-Yu; Sorloaica-Hickman, Nicoleta

    2011-09-01

    Lunar grains accumulate charges due to solar-based ionizing radiations, and the repelling action of like-charged particles causes the levitation of lunar dust. The lunar dust deposit on sensitive and costly surfaces of investigative equipment is a serious concern in lunar explorations. Inspired by electrostatic precipitators (ESPs), the Electrostatic Lunar Dust Collector (ELDC) was proposed for collecting already charged lunar dust particles to prevent the lunar dust threat. As the conditions for terrestrial counterparts are not valid in the lunar environment, equations developed for terrestrial devices yield incorrect predictions in lunar application. Hence, a mathematical model was developed for the ELDC operating in vacuum to determine its collection efficiency. The ratios of electrical energy over potential energy, kinetic energy over potential energy and the ratio of ELDC dimensions were identified to be the key dimensionless parameters. Sensitivity analyses of the relevant parameters showed that depending on ELDC orientation, smaller particles would be collected more easily at vertical orientation, whereas larger particles were easier to collect in a horizontal ELDC configuration. In the worst case scenario, the electrostatic field needed to be 10 times stronger in the vertical mode in order to adequately collect larger particles. The collection efficiency was very sensitive to surface potential of lunar dust and it reached the maximum when surface potential was between 30 and 120 V. Except for regions of the lunar day side with surface potential close to zero, providing 1 kV ( E = 20 kV m -1) with the ELDC was more than enough for collecting all the particles in the most critical orientation. The needed field strength was about 4000 times less than that for repelling 1-μm size particles already settled on the surfaces. The analysis shows that the ELDC offers a viable solution for lunar dust control due to its effectiveness, ease of cleaning and low voltage

  19. Electrostatic beneficiation of coal

    SciTech Connect

    Mazumder, M.K.; Tennal, K.B.; Lindquist, D.

    1994-10-01

    Dry physical beneficiation of coal has many advantages over wet cleaning methods and post combustion flue gas cleanup processes. The dry beneficiation process is economically competitive and environmentally safe and has the potential of making vast amounts of US coal reserves available for energy generation. While the potential of the electrostatic beneficiation has been studied for many years in laboratories and in pilot plants, a successful full scale electrostatic coal cleaning plant has not been commercially realized yet. In this paper the authors review some of the technical problems that are encountered in this method and suggest possible solutions that may lead toward its full utilization in cleaning coal.

  20. Electrostatic graphene loudspeaker

    NASA Astrophysics Data System (ADS)

    Zhou, Qin; Zettl, A.

    2013-06-01

    Graphene has extremely low mass density and high mechanical strength, and key qualities for efficient wide-frequency-response electrostatic audio speaker design. Low mass ensures good high frequency response, while high strength allows for relatively large free-standing diaphragms necessary for effective low frequency response. Here, we report on construction and testing of a miniaturized graphene-based electrostatic audio transducer. The speaker/earphone is straightforward in design and operation and has excellent frequency response across the entire audio frequency range (20 Hz-20 kHz), with performance matching or surpassing commercially available audio earphones.

  1. Electrostatic Levitator Vacuum Chamber

    NASA Technical Reports Server (NTRS)

    1998-01-01

    Optical ports ring the Electrostatic Levitator (ESL) vacuum chamber to admit light from the heating laser (beam passes through the window at left), positioning lasers (one port is at center), and lamps to allow diagnostic instruments to view the sample. The ESL uses static electricity to suspend an object (about 2-3 mm in diameter) inside a vacuum chamber while a laser heats the sample until it melts. This lets scientists record a wide range of physical properties without the sample contacting the container or any instruments, conditions that would alter the readings. The Electrostatic Levitator is one of several tools used in NASA's microgravity materials science program.

  2. Electrostatic Levitator Inspected

    NASA Technical Reports Server (NTRS)

    1998-01-01

    Larry Savage, Dr. Jan Rogers, Dr. Michael Robinson (All NASA) and Doug Huie (Mevatec) inspect the Electrostatic Levitator (ESL) at NASA's Marshall Space Flight Center (MSFC). The ESL uses static electricity to suspend an object (about 2-3 mm in diameter) inside a vacuum chamber while a laser heats the sample until it melts. This lets scientists record a wide range of physical properties without the sample contacting the container or any instruments, conditions that would alter the readings. The Electrostatic Levitator is one of several tools used in NASA's microgravity materials science program.

  3. Electrostatic Levitator (ESL) Undercooling

    NASA Technical Reports Server (NTRS)

    1998-01-01

    Graph depicting Electrostatic Levitator (ESL) heating and cooling cycle to achieve undercooling of liquid metals. The ESL uses static electricity to suspend an object (about 3-4 mm in diameter) inside a vacuum chamber while a laser heats the sample until it melts. This lets scientists record a wide range of physical properties without the sample contracting the container or any instruments, conditions that would alter the readings. The electrostatic Levitator is one of several tools used in NASA's microgravity matierials sciences program.

  4. Electrostatic Levitator at Work

    NASA Technical Reports Server (NTRS)

    2000-01-01

    A 3 mm drop of nickel-zirconium, heated to incandescence, hovers between electrically charged plates inside the Electrostatic Levitator (ESL). The ESL uses static electricity to suspend an object (about 2-3 mm in diameter) inside a vacuum chamber while a laser heats the sample until it melts. This lets scientists record a wide range of physical properties without the sample contacting the container or any instruments, conditions that would alter the readings. The Electrostatic Levitator is one of several tools used in NASA's microgravity materials science program.

  5. Electrostatic interactions between Janus particles

    NASA Astrophysics Data System (ADS)

    de Graaf, Joost; Boon, Niels; Dijkstra, Marjolein; van Roij, René

    2012-09-01

    In this paper we study the electrostatic properties of "Janus" spheres with unequal charge densities on both hemispheres. We introduce a method to compare primitive-model Monte Carlo simulations of the ionic double layer with predictions of (mean-field) nonlinear Poisson-Boltzmann theory. We also derive practical Derjaguin Landau Verwey Overbeek (DLVO)-like expressions that describe the Janus-particle pair interactions by mean-field theory. Using a large set of parameters, we are able to probe the range of validity of the Poisson-Boltzmann approximation, and thus of DLVO-like theories, for such particles. For homogeneously charged spheres this range corresponds well to the range that was predicted by field-theoretical studies of homogeneously charged flat surfaces. Moreover, we find similar ranges for colloids with a Janus-type charge distribution. The techniques and parameters we introduce show promise for future studies of an even wider class of charged-patterned particles.

  6. Using electrostatic modelling to study cone discharges

    NASA Astrophysics Data System (ADS)

    Azizi, W.

    2015-10-01

    Cone discharges, also known as bulking brush discharges, can arise when charged insulating powder accumulates in a heap in silos. They can be an effective ignition source to relatively ignition sensitive powders and therefore represent a possible electrostatic hazard. The current international guidance on control of electrostatic hazards (IEC/TS 60079-32-1 [1]), endorses the usage of electrostatic modelling to estimate the electric field above the powder heap. “Such model calculations should be based on the charge to mass ratio, bulk density and filling rate of the powder, the relative permittivity and resistivity of the bulked powder as well as the silo geometry.” This study shows a practical demonstration of this modelling technique. It also examines whether the shape of the heap affects the strength of the electric field above the powder heap, and thus the likelihood of cone discharges from occurring.

  7. Optimization design combined with coupled structural-electrostatic analysis for the electrostatically controlled deployable membrane reflector

    NASA Astrophysics Data System (ADS)

    Liu, Chao; Yang, Guigeng; Zhang, Yiqun

    2015-01-01

    The electrostatically controlled deployable membrane reflector (ECDMR) is a promising scheme to construct large size and high precision space deployable reflector antennas. This paper presents a novel design method for the large size and small F/D ECDMR considering the coupled structure-electrostatic problem. First, the fully coupled structural-electrostatic system is described by a three field formulation, in which the structure and passive electrical field is modeled by finite element method, and the deformation of the electrostatic domain is predicted by a finite element formulation of a fictitious elastic structure. A residual formulation of the structural-electrostatic field finite element model is established and solved by Newton-Raphson method. The coupled structural-electrostatic analysis procedure is summarized. Then, with the aid of this coupled analysis procedure, an integrated optimization method of membrane shape accuracy and stress uniformity is proposed, which is divided into inner and outer iterative loops. The initial state of relatively high shape accuracy and uniform stress distribution is achieved by applying the uniform prestress on the membrane design shape and optimizing the voltages, in which the optimal voltage is computed by a sensitivity analysis. The shape accuracy is further improved by the iterative prestress modification using the reposition balance method. Finally, the results of the uncoupled and coupled methods are compared and the proposed optimization method is applied to design an ECDMR. The results validate the effectiveness of this proposed methods.

  8. Electrostatically driven complexation

    NASA Astrophysics Data System (ADS)

    Netz, Roland

    2004-03-01

    Many biological and synthetic systems are electrically charged, which makes them soluble in aqueous environments. Often, electrostatic interactions are dominant, and lead to complexation (i.e. tight aggregation) of oppositely charged objects. As an example, charged polymers such as DNA exhibit a number of different complexation modes when mixed with other charged objects such as spheres or cylinders. A simple model for the complexation of semiflexible polyelectrolytes with oppositely charged spheres is considered, which can exhibit tightly wrapped polymer structures. Using the appropriate parameters for DNA-histone complexes, one finds complete wrapping for intermediate salt concentrations only, in agreement with experiments. The forces needed to pull the DNA off from histones show a plateau at 10-40 pN (depending on salt concentration). We also consider the interaction between such complexes, which have been measured using osmometry, and found to be attractive for intermediate salt concentration (suggesting precipitation) and repulsive elsewhere. Chain fluctuations can be treated within a normal-mode analysis and distinguish associated-unwrapped from dissociated structures. Since some time it is known that also similarly charged objects attract each other for sufficiently large surface-charge densities and/or in the presence of multivalent ions, a phenomenon not explicable within standard (Poisson-Boltzmann) approaches. The so-called strong-coupling theory, valid in the limit of large surface charge densities and for multi-valent ions, yields attraction between similarly charged walls, cylinders, and spheres in quantitative agreement with Monte-Carlo simulations. Charged complexes can be destroyed by applying an electric field, which is an important factor in understanding their electrophoresis. By performing dynamic simulations, the relation between the electrophoretic mobility and the non-equilibrium perturbation of the complex structure is investigated. 1

  9. Status of ferrite technology for high volume microwave applications

    SciTech Connect

    Webb, D.C.

    1995-08-01

    With the emergence of high volume commercial and military applications, there is a growing need to reduce the size and cost of microwave ferrite components, especially ferrite circulators, to be more compatible with monolithic integrated circuits. The Ferrite Development Consortium, consisting of leading US ferrite government, university and industrial institutions, was formed under Advanced Research Project Agency (ARPA) sponsorship to address these needs. Areas of Consortium technical activity include bulk and thick-film techniques for batch processing of ferrite devices, improved computer-aided-design tools and protype demonstrations. This paper will review the Consortium`s materials development needs and progress.

  10. Step and flash imprint lithography for semiconductor high volume manufacturing?

    NASA Astrophysics Data System (ADS)

    Malloy, M.; Litt, L. C.

    2010-03-01

    Step and Flash Imprint Lithography (SFIL), a form of ultraviolet nanoimprint lithography (UV-NIL), is recognized for its resolution and patterning abilities. It is one of the few next generation lithography techniques capable of meeting the resolution requirements of future semiconductor devices. However, many integration issues such as defectivity, throughput, and overlay must be resolved before SFIL can be used for semiconductor high volume manufacturing (HVM). This paper discusses the current status of SFIL, including the process and templates, and shows where more industry collaboration is needed to solve the most critical issues.

  11. Breakdown mechanisms in electrostatic deflector

    NASA Astrophysics Data System (ADS)

    Re, M.; Cuttone, G.; Zappalà, E.; Passarello, S.

    2001-12-01

    The Electrostatic Beam Deflectors for the K800 Superconducting Cyclotron are the most critical elements of the beam extraction system. It has been carried out an accurate investigation from the microscopic point of view, leading to a better comprehension of the complex phenomena taking part in the breakdown process. The environmental conditions are high electric field (up to 130 kV/cm), high magnetic field (up to 5 T) in addition with high energy (70 MeV/u) and high power ion beam. It has been found that all the materials constituent the electrostatic deflector, and not only the electrodes, give an important contribute to the mechanism of breakdown that occurs in two main ways: insulator metalization and enhanced electrodes electron emission. These two effects are involved in a positive feedback process which amplifies the effects leading to a fast breakdown. These phenomena are here shown and some possible solutions are at the moment under test using several bulk (Mo, Ti, Cu) and coating materials (TiN, Diamond Like Carbon).

  12. Electrostatic space radiation shielding

    NASA Astrophysics Data System (ADS)

    Tripathi, R.; Wilson, J. W.; Youngquist, R. C.

    For the success of NASA s new vision for space exploration to Moon Mars and beyond exposures from the hazards of severe space radiation in deep space long duration missions is a must solve problem The payload penalty demands a very stringent requirement on the design of the spacecrafts for human deep space missions The exploration beyond low Earth orbit LEO to enable routine access of space will require protection from the hazards of the accumulated exposures of space radiation Galactic Cosmic Rays GCR and Solar Particle Events SPE and minimizing the production of secondary radiation is a great advantage There is a need to look to new horizons for newer technologies The present investigation revisits electrostatic active radiation shielding and explores the feasibility of using the electrostatic shielding in concert with the state-of-the-art materials shielding and protection technologies The full space radiation environment has been used for the first time to explore the feasibility of electrostatic shielding The goal is to repel enough positive charge ions so that they miss the spacecraft without attracting thermal electrons Conclusions will be drawn should the electrostatic shielding be successful for the future directions of space radiation protection

  13. Electrostatics of Rigid Polyelectrolytes

    SciTech Connect

    Wong, G.C.L.

    2009-06-04

    The organization of rigid biological polyelectrolytes by multivalent ions and macroions are important for many fundamental problems in biology and biomedicine, such as cytoskeletal regulation and antimicrobial sequestration in cystic fibrosis. These polyelectrolytes have been used as model systems for understanding electrostatics in complex fluids. Here, we review some recent results in theory, simulations, and experiments.

  14. Electrostatically Enhanced Vortex Separator

    NASA Technical Reports Server (NTRS)

    Collins, Earl R.

    1993-01-01

    Proposed device removes fine particles from high-pressure exhaust gas of chemical reactor. Negatively charged sectors on rotating disks in vortex generator attracts positively charged particles from main stream of exhaust gas. Electrostatic charge enhances particle-separating action of vortex. Gas without particles released to atmosphere.

  15. An asymmetry in electrostatics

    NASA Astrophysics Data System (ADS)

    Ganci, Salvatore

    2013-11-01

    This paper outlines a misuse of the electrostatic induction concept. A non-symmetrical behaviour was observed in a charge by the induction of an insulated hollow metallic conductor (the Faraday ice pail experiment). The major consequence of this experiment is a quick demonstration that the Earth must have a net negative charge.

  16. A Bridge between Two Important Problems in Optics and Electrostatics

    ERIC Educational Resources Information Center

    Capelli, R.; Pozzi, G.

    2008-01-01

    It is shown how the same physically appealing method can be applied to find analytic solutions for two difficult and apparently unrelated problems in optics and electrostatics. They are: (i) the diffraction of a plane wave at a perfectly conducting thin half-plane and (ii) the electrostatic field associated with a parallel array of stripes held at…

  17. A Bridge between Two Important Problems in Optics and Electrostatics

    ERIC Educational Resources Information Center

    Capelli, R.; Pozzi, G.

    2008-01-01

    It is shown how the same physically appealing method can be applied to find analytic solutions for two difficult and apparently unrelated problems in optics and electrostatics. They are: (i) the diffraction of a plane wave at a perfectly conducting thin half-plane and (ii) the electrostatic field associated with a parallel array of stripes held at…

  18. Energy expenditure of swimmers during high volume training.

    PubMed

    Trappe, T A; Gastaldelli, A; Jozsi, A C; Troup, J P; Wolfe, R R

    1997-07-01

    The purpose of this study was to examine the total energy expenditure (TEE) of swimmers during high volume training (17.5 +/- 1.0 km.d-1) using the doubly labeled water method. Five female swimmers (age, 19 +/- 1 yr; height, 178.3 +/- 2.2 cm; weight 65.4 +/- 1.6 kg) were administered a dose of 2H2(18)O and monitored for 5 days. Training consisted of two sessions per day, lasting a total of 5-6 h. Energy intake (EI) was calculated from dietary records. Resting energy expenditure (REE) was measured on a non-training day and averaged 7.7 +/- 0.5 MJ.d-1 (1840 +/- 130 kcal.d-1). There were no changes in body weight (day 1, 65.4 +/- 1.6; day 5, 65.2 +/ 1.5 kg) over the measurement period. TEE of the swimmers during the training period averaged 23.4 +/- 2.1 MJ.d-1 (5593 +/- 495 kcal.d-1). EI averaged 13.1 +/- 1.0 MJ.d-1 (3136 +/- 227 kcal.d-1), implying a negative energy balance of 43 +/- 2%. TEE expressed as a multiple of REE was 3.0 +/- 0.2. The results of this investigation describe the total energy demands of high volume swimming training, which may be used to address the dietary concerns of the competitive swimming athlete.

  19. Electrostatic supersolitons in three-species plasmas

    SciTech Connect

    Verheest, Frank; Hellberg, Manfred A.; Kourakis, Ioannis

    2013-01-15

    Superficially, electrostatic potential profiles of supersolitons look like those of traditional solitons. However, their electric field profiles are markedly different, having additional extrema on the wings of the standard bipolar structure. This new concept was recently pointed out in the literature for a plasma model with five species. Here, it is shown that electrostatic supersolitons are not an artefact of exotic, complicated plasma models, but can exist even in three-species plasmas and are likely to occur in space plasmas. Further, a methodology is given to delineate their existence domains in a systematic fashion by determining the specific limiting factors.

  20. Electrostatics of Deformable Lipid Membranes

    PubMed Central

    Vorobyov, Igor; Bekker, Borislava; Allen, Toby W.

    2010-01-01

    Abstract It was recently demonstrated that significant local deformations of biological membranes take place due to the fields of charged peptides and ions, challenging the standard model of membrane electrostatics. The ability of ions to retain their immediate hydration environment, combined with the lack of sensitivity of permeability to ion type or even ion pairs, led us to question the extent to which hydration energetics and electrostatics control membrane ion permeation. Using the arginine analog methyl-guanidinium as a test case, we find that although hydrocarbon electronic polarizability causes dramatic changes in ion solvation free energy, as well as a significant change (∼0.4 V) in the membrane dipole potential, little change in membrane permeation energetics occurs. We attribute this to compensation of solvation terms from polar and polarizable nonpolar components within the membrane, and explain why the dipole potential is not fully sensed in terms of the locally deformed bilayer interface. Our descriptions provide a deeper understanding of the translocation process and allow predictions for poly-ions, ion pairs, charged lipids, and lipid flip-flop. We also report simulations of large hydrophobic-ion-like membrane defects and the ionophore valinomycin, which exhibit little membrane deformation, as well as hydrophilic defects and the ion channel gramicidin A, to provide parallels to membranes deformed by unassisted ion permeation. PMID:20550903

  1. Automated Electrostatics Environmental Chamber

    NASA Technical Reports Server (NTRS)

    Calle, Carlos; Lewis, Dean C.; Buchanan, Randy K.; Buchanan, Aubri

    2005-01-01

    The Mars Electrostatics Chamber (MEC) is an environmental chamber designed primarily to create atmospheric conditions like those at the surface of Mars to support experiments on electrostatic effects in the Martian environment. The chamber is equipped with a vacuum system, a cryogenic cooling system, an atmospheric-gas replenishing and analysis system, and a computerized control system that can be programmed by the user and that provides both automation and options for manual control. The control system can be set to maintain steady Mars-like conditions or to impose temperature and pressure variations of a Mars diurnal cycle at any given season and latitude. In addition, the MEC can be used in other areas of research because it can create steady or varying atmospheric conditions anywhere within the wide temperature, pressure, and composition ranges between the extremes of Mars-like and Earth-like conditions.

  2. Electrostatically clean solar array

    NASA Technical Reports Server (NTRS)

    Stern, Theodore Garry (Inventor); Krumweide, Duane Eric (Inventor)

    2004-01-01

    Provided are methods of manufacturing an electrostatically clean solar array panel and the products resulting from the practice of these methods. The preferred method uses an array of solar cells, each with a coverglass where the method includes machining apertures into a flat, electrically conductive sheet so that each aperture is aligned with and undersized with respect to its matched coverglass sheet and thereby fashion a front side shield with apertures (FSA). The undersized portion about each aperture of the bottom side of the FSA shield is bonded to the topside portions nearest the edges of each aperture's matched coverglass. Edge clips are attached to the front side aperture shield edges with the edge clips electrically and mechanically connecting the tops of the coverglasses to the solar panel substrate. The FSA shield, edge clips and substrate edges are bonded so as to produce a conductively grounded electrostatically clean solar array panel.

  3. Biobriefcase electrostatic aerosol collector

    DOEpatents

    Bell, Perry M.; Christian, Allen T.; Bailey, Christopher G.; Willis, Ladona; Masquelier, Donald A.; Nasarabadi, Shanavaz L.

    2009-03-17

    A system for sampling air and collecting particles entrained in the air comprising a receiving surface, a liquid input that directs liquid to the receiving surface and produces a liquid surface, an air input that directs the air so that the air with particles entrained in the air impact the liquid surface, and an electrostatic contact connected to the liquid that imparts an electric charge to the liquid. The particles potentially including bioagents become captured in the liquid by the air with particles entrained in the air impacting the liquid surface. Collection efficiency is improved by the electrostatic contact electrically charging the liquid. The effects of impaction and adhesion due to electrically charging the liquid allows a unique combination in a particle capture medium that has a low fluid consumption rate while maintaining high efficiency.

  4. Electrostatic Levitator Vacuum Chambers

    NASA Technical Reports Server (NTRS)

    1998-01-01

    Optical prots ring the Electrostatic Levitator (ESL) vacuum chamber to admit light from the heating laser (the beam passes through the window at left), poisitioning lasers (one port is at center), and lamps (such as the deuterium arc lamp at right), and to allow diagnostic instruments to view the sample. The ESL uses static electricity to suspend an object (about 2-3 mm in diameter) inside a vacuum chamber while a laser heats the sample until it melts. This lets scientists record a wide range of physical properties without the sample contacting the container or any instruments, conditions that would alter the readings. The Electrostatic Levitator is one of several tools used in NASA's microgravity materials science program.

  5. Copper emissions from a high volume air sampler

    NASA Technical Reports Server (NTRS)

    King, R. B.; Toma, J.

    1975-01-01

    High volume air samplers (hi vols) are described which utilize a brush-type electric motor to power the fans used for pulling air through the filter. Anomalously high copper values were attributed to removal of copper from the commutator into the air stream due to arcing of the brushes and recirculation through the filter. Duplicate hi vols were set up under three operating conditions: (1) unmodified; (2) gasketed to prevent internal recirculation; and (3) gasketed and provided with a pipe to transport the motor exhaust some 20 feet away. The results of 5 days' operation demonstrate that hi vols can suddenly start emitting increased amounts of copper with no discernible operational indication, and that recirculation and capture on the filter can take place. Copper levels found with hi vols whose exhaust was discharged at a distance downwind were among the lowest found, and apparently provides a satisfactory solution to copper contamination.

  6. A high volume, batch mode 129Xe polarizer

    NASA Astrophysics Data System (ADS)

    Wojna-Pelczar, Anna; Pałasz, Tadeusz

    2017-06-01

    Numerous designs of optical gas polarizers have been proposed, broadening possible applications of the hyperpolarized gases as contrast agents in magnetic resonance imaging. We present a home-made 129Xe polarizer based on the spin exchange optical pumping method. The polarizer operates under 1 bar of the gas mixture (at the maximum temperature of 160 °C) in a high volume optical cell (5025 cm3). Approximately 100 cm3 of 129Xe polarized at 1.50±0.37% is produced in a single cycle of polarization. Operation under standard pressure imposes polarization transfer mainly via van der Waals molecules, resulting in the efficient spin exchange between rubidium and 129Xe atoms. The design, construction and operation of the polarizer are described in details.

  7. Ultra-fast MTF Test for High-Volume production of CMOS Imaging Cameras

    NASA Astrophysics Data System (ADS)

    Dahl, Michael; Heinisch, Josef; Krey, Stefan; Bäumer, Stefan M.; Lurquin, Johan; Chen, Linghua

    2004-01-01

    During the last years compact CMOS imaging cameras have grown into high volume applications such as mobile phones, PDAs, etc. In order to insure a constant quality of the lenses of the cameras, MTF is used as a figure of merit. MTF is a polychromatic, objective test for imaging lens quality including diffraction effects, system aberrations and surface defects as well. The draw back of MTF testing is that the proper measurement of the lens MTF is quite cumbersome and time consuming. In the current investigation we designed, produced and tested a new semi-automated MTF set up that is able to measure the polychromatic lens system MTF at 6 or more field points at best focus in less than 6 seconds. The computed MTF is a real diffraction MTF derived from a line spread function (not merely a contrast measurement). This enables lens manufacturers to perform 100% MTF testing even in high volume applications. Using statistic tools to analyze the data also gives possibility to find even small systematic errors in the production like shift or tilt of lenses and lens elements. Using this as feedback the quality of the product can be increased. The system is very compact and can be put easily in an assembly line. Besides design and test of the MTF set up correlation experiments between several testers have been carried out. A correlation of better than 6% points for all tested systems at all fields has been achieved.

  8. Electrostatic Levitator Operations

    NASA Technical Reports Server (NTRS)

    1998-01-01

    Dr. Jan Rogers (left) and Larry Savage (foreground) of the Science Directorate at NASA's Marshall Space Flight Center are joined by Dr. Richard Weber (Center) and April Hixon of Containerless Research Inc. of Evanston, Ill., in conducting an experiment run of the Electrostatic Levitator (ESL) using insulating materials. Materials researchers use unique capability of the facility to levitate and study the properties of various materials important in manufacturing processes.

  9. Development of a high-volume air sampler for nanoparticles.

    PubMed

    Hata, M; Thongyen, T; Bao, L; Hoshino, A; Otani, Y; Ikeda, T; Furuuchi, M

    2013-02-01

    As a tool to evaluate the characteristics of aerosol nano-particles, a high-volume air sampler for the collection of nano-particles was developed based on the inertial filter technology. Instead of the webbed fiber geometry of the existing inertial filter, wire mesh screens alternately layered using spacing sheets with circular holes aligned to provide multi-circular nozzles were newly devised and the separation performance of the filter was investigated experimentally. The separation performance was evaluated for a single-nozzle inertial filter at different filtration velocities. A webbed stainless steel fiber mat attached on the inlet surface of the developed inertial filter was discussed as a pre-separator suppressing the bouncing of particles on meshes. The separation performance of a triple-nozzle inertial filter was also discussed to investigate the influence of scale-up on the separation performance of a multi-nozzle inertial filter. The influence of particle loading on the pressure drop and separation performance was discussed. A supplemental inlet for the nano-particle collection applied to an existing portable high-volume air sampler was devised and the consistency with other types of existing samplers was discussed based on the sampling of ambient particles. The layered-mesh inertial filter with a webbed stainless steel fiber mat as a pre-separator showed good performance in the separation of particles with a d p50 ranging from 150 to 190 nm keeping the influence of loaded particles small. The developed layered-mesh inertial filter was successfully applied to the collection of particles at a d p50∼ 190 nm that was consistent with the results from existing samplers.

  10. Electrostatics of Granular Materials

    NASA Technical Reports Server (NTRS)

    Marshall, John

    2004-01-01

    The purpose of the research was to continue developing an understanding of electrostatic phenomena in preparation for any future flight opportunities of the EGM experiment, originally slated for a 2004 Space Station deployment. Work would be based on theoretical assessments, ground-based lab experiments, and reduced-gravity experiments. The ability to examine dipoles in the lab proved to be elusive, and thus, effort was concentrated on monopoles -how materials become charged, the fate of the charge, the role of material type, and so forth. Several significant milestones were achieved in this regard. In regard of the dipoles, experiments were designed in collaboration with the University of Chicago school district who had access to reduced gravity on the KC-135 aircraft. Two experiments were slated to fly last year but were cancelled after the Columbia accident. One of the experiments has been given a second life and will fly sometime in 2005 if the Shuttle flights resume. There remains active interest in the question of electrostatic dipoles within the educational community, and experiments using magnetic dipoles as a substitute are to be examined. The KC-135 experiments will also examine dispersion methods for particles as a verification of possible future techniques in microgravity. Both laboratory and theoretical work established a number of breakthroughs in our understanding of electrostatic phenomena. These breakthroughs are listed in this paper.

  11. Electrostatic Plasma Accelerator (EPA)

    NASA Technical Reports Server (NTRS)

    Brophy, John R.; Aston, Graeme

    1989-01-01

    The Electrostatic Plasma Accelerator (EPA) is a thruster concept which promises specific impulse levels between low power arcjets and those of the ion engine while retaining the relative simplicity of the arcjet. The EPA thruster produces thrust through the electrostatic acceleration of a moderately dense plasma. No accelerating electrodes are used and the specific impulse is a direct function of the applied discharge voltage and the propellant atomic mass. The goal of the present program is to demonstrate feasibility of the EPA thruster concept through experimental and theoretical investigations of the EPA acceleration mechanism and discharge chamber performance. Experimental investigations will include operating the test bed ion (TBI) engine as an EPA thruster and parametrically varying the thruster geometry and operating conditions to quantify the electrostatic plasma acceleration effect. The theoretical investigations will include the development of a discharge chamber model which describes the relationships between the engine size, plasma properties, and overall performance. For the EPA thruster to be a viable propulsion concept, overall thruster efficiencies approaching 30% with specific impulses approaching 1000 s must be achieved.

  12. Electrostatic space radiation shielding

    NASA Astrophysics Data System (ADS)

    Tripathi, Ram K.; Wilson, John W.; Youngquist, Robert C.

    2008-09-01

    For the success of NASA’s new vision for space exploration to Moon, Mars and beyond, exposures from the hazards of severe space radiation in deep space long duration missions is ‘a must solve’ problem. The payload penalty demands a very stringent requirement on the design of the spacecrafts for human deep space missions. The exploration beyond low Earth orbit (LEO) to enable routine access of space will require protection from the hazards of the accumulated exposures of space radiation, Galactic Cosmic Rays (GCR) and Solar Particle Events (SPE), and minimizing the production of secondary radiation is a great advantage. There is a need to look to new horizons for newer technologies. The present investigation revisits electrostatic active radiation shielding and explores the feasibility of using the electrostatic shielding in concert with the state-of-the-art materials shielding and protection technologies. The full space radiation environment has been used, for the first time, to explore the feasibility of electrostatic shielding. The goal is to repel enough positive charge ions so that they miss the spacecraft without attracting thermal electrons. Conclusions are drawn for the future directions of space radiation protection.

  13. Microencapsulation and Electrostatic Processing Method

    NASA Technical Reports Server (NTRS)

    Morrison, Dennis R. (Inventor); Mosier, Benjamin (Inventor)

    2000-01-01

    Methods are provided for forming spherical multilamellar microcapsules having alternating hydrophilic and hydrophobic liquid layers, surrounded by flexible, semi-permeable hydrophobic or hydrophilic outer membranes which can be tailored specifically to control the diffusion rate. The methods of the invention rely on low shear mixing and liquid-liquid diffusion process and are particularly well suited for forming microcapsules containing both hydrophilic and hydrophobic drugs. These methods can be carried out in the absence of gravity and do not rely on density-driven phase separation, mechanical mixing or solvent evaporation phases. The methods include the process of forming, washing and filtering microcapsules. In addition, the methods contemplate coating microcapsules with ancillary coatings using an electrostatic field and free fluid electrophoresis of the microcapsules. The microcapsules produced by such methods are particularly useful in the delivery of pharmaceutical compositions.

  14. Electrostatic transfer of epitaxial graphene to glass.

    SciTech Connect

    Ohta, Taisuke; Pan, Wei; Howell, Stephen Wayne; Biedermann, Laura Butler; Beechem Iii, Thomas Edwin; Ross, Anthony Joseph, III

    2010-12-01

    We report on a scalable electrostatic process to transfer epitaxial graphene to arbitrary glass substrates, including Pyrex and Zerodur. This transfer process could enable wafer-level integration of graphene with structured and electronically-active substrates such as MEMS and CMOS. We will describe the electrostatic transfer method and will compare the properties of the transferred graphene with nominally-equivalent 'as-grown' epitaxial graphene on SiC. The electronic properties of the graphene will be measured using magnetoresistive, four-probe, and graphene field effect transistor geometries [1]. To begin, high-quality epitaxial graphene (mobility 14,000 cm2/Vs and domains >100 {micro}m2) is grown on SiC in an argon-mediated environment [2,3]. The electrostatic transfer then takes place through the application of a large electric field between the donor graphene sample (anode) and the heated acceptor glass substrate (cathode). Using this electrostatic technique, both patterned few-layer graphene from SiC(000-1) and chip-scale monolayer graphene from SiC(0001) are transferred to Pyrex and Zerodur substrates. Subsequent examination of the transferred graphene by Raman spectroscopy confirms that the graphene can be transferred without inducing defects. Furthermore, the strain inherent in epitaxial graphene on SiC(0001) is found to be partially relaxed after the transfer to the glass substrates.

  15. An interpretation of electrostatic density shocks in space plasma

    SciTech Connect

    Shi Jiankui; Zhang Tielong; Torkar, Klaus; Liu Zhenxing

    2005-08-15

    A physical model of electrostatic shocks observed in space plasma is established by deriving the 'Sagdeev potential' from the magnetohydrodynamic equations in a cylindrical coordinate system. The results show that the electrostatic density shock and its corresponding solitary electric-field structure can develop from an ion acoustic wave or an ion cyclotron wave if the Mach number and the initial electric field satisfy some conditions. Some features of the shock wave are discussed. The result can be used to interpret the electrostatic shock observed in geospace plasma.

  16. ELECTROSTATIC MODE ASSOCIATED WITH PINCH VELOCITY IN RFPS

    SciTech Connect

    DELZANNO, GIAN LUCA; FINN, JOHN M.; CHACON, LUIS

    2007-02-08

    The existence of a new electrostatic instability is shown for RFP (reversed field pinch) equilibria. This mode arises due to the non-zero equilibrium radial flow (pinch flow). In RFP simulations with no-stress boundary conditions on the tangential velocity at the radial wall, this electrostatic mode is unstable and dominates the nonlinear dynamics, even in the presence of the MHD modes typically responsible for the reversal of the axial magnetic field at edge. Nonlinearly, this mode leads to two beams moving azimuthally towards each other, which eventually collide. The electrostatic mode can be controlled by using Dirichlet (no-slip) boundary conditions on the azimuthal velocity at the radial wall.

  17. High-volume haemofiltration for sepsis in adults.

    PubMed

    Borthwick, Emma Mj; Hill, Christopher J; Rabindranath, Kannaiyan S; Maxwell, Alexander P; McAuley, Danny F; Blackwood, Bronagh

    2017-01-31

    Severe sepsis and septic shock are leading causes of death in the intensive care unit (ICU), despite advances in the treatment of patients with severe sepsis and septic shock, including early recognition, appropriate treatment with antibiotics and support of organs that may have been affected by the illness. High-volume haemofiltration (HVHF) is a blood purification technique that may improve outcomes in severe sepsis or septic shock. The technique of HVHF has evolved from renal replacement therapies used in the ICU to treat critically ill patients with acute kidney injury (AKI). This review was first published in 2013 and was updated in 2016. To investigate whether HVHF improves outcomes in critically ill adults admitted to the intensive care unit with severe sepsis or septic shock. The primary outcome of this systematic review is patient mortality; secondary outcomes include duration of stay, severity of organ dysfunction and adverse events. For this updated version, we extended searches of the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, Latin American Caribbean Health Sciences Literature (LILACS), Web of Science and the Cumulative Index to Nursing and Allied Health Literature (CINAHL) to 31 December 2015. The original search was performed in 2011. We also searched trials registers. We included randomized controlled trials (RCTs) and quasi-randomized trials comparing HVHF or high-volume haemodiafiltration versus standard or usual dialysis therapy, as well as RCTs and quasi-randomized trials comparing HVHF or high-volume haemodiafiltration versus no similar dialysis therapy. These studies involved adults treated in critical care units. Three review authors independently extracted data and assessed trial quality. We sought additional information from trialists as required. We included four randomized trials involving 200 participants. Owing to small numbers of studies and participants, it was not possible to combine data for all

  18. A simplified electrostatic model for hydrolase catalysis.

    PubMed

    Pessoa Filho, Pedro de Alcantara; Prausnitz, John M

    2015-07-01

    Toward the development of an electrostatic model for enzyme catalysis, the active site of the enzyme is represented by a cavity whose surface (and beyond) is populated by electric charges as determined by pH and the enzyme's structure. The electric field in the cavity is obtained from electrostatics and a suitable computer program. The key chemical bond in the substrate, at its ends, has partial charges with opposite signs determined from published force-field parameters. The electric field attracts one end of the bond and repels the other, causing bond tension. If that tension exceeds the attractive force between the atoms, the bond breaks; the enzyme is then a successful catalyst. To illustrate this very simple model, based on numerous assumptions, some results are presented for three hydrolases: hen-egg white lysozyme, bovine trypsin and bovine ribonuclease. Attention is given to the effect of pH.

  19. Novel electrostatic trap for cold polar molecules

    NASA Astrophysics Data System (ADS)

    Xu, Xue-Yan; Ma, Hui; Yin, Jian-Ping

    2007-12-01

    We propose a novel scheme in which cold polar molecules are trapped by an electrostatic field generated by the combination of a pair of parallel transparent electrodes (i.e., two infinite transparent plates) and a ring electrode (i.e., a ring wire). The spatial distributions of the electrostatic fields from the above charged wire and the charged plates and the corresponding Stark potentials for cold CO molecules are calculated; the dependences of the trap centre position on the geometric parameters of the electrode are analysed. We also discuss the loading process of cold molecules from a cold molecular beam into our trap. This study shows that the proposed scheme is not only simple and convenient to trap, manipulate and control cold polar molecules in weak-field-seeking states, but also provides an opportunity to study cold collisions and collective quantum effects in a variety of cold molecular systems, etc.

  20. High-Temperature-High-Volume Lifting for Enhanced Geothermal Systems

    SciTech Connect

    Turnquist, Norman; Qi, Xuele; Raminosoa, Tsarafidy; Salas, Ken; Samudrala, Omprakash; Shah, Manoj; Van Dam, Jeremy; Yin, Weijun; Zia, Jalal

    2013-12-20

    This report summarizes the progress made during the April 01, 2010 – December 30, 2013 period under Cooperative Agreement DE-EE0002752 for the U.S. Department of Energy entitled “High-Temperature-High-Volume Lifting for Enhanced Geothermal Systems.” The overall objective of this program is to advance the technology for well fluids lifting systems to meet the foreseeable pressure, temperature, and longevity needs of the Enhanced Geothermal Systems (EGS) industry for the coming ten years. In this program, lifting system requirements for EGS wells were established via consultation with industry experts and site visits. A number of artificial lift technologies were evaluated with regard to their applicability to EGS applications; it was determined that a system based on electric submersible pump (ESP) technology was best suited to EGS. Technical barriers were identified and a component-level technology development program was undertaken to address each barrier, with the most challenging being the development of a power-dense, small diameter motor that can operate reliably in a 300°C environment for up to three years. Some of the targeted individual component technologies include permanent magnet motor construction, high-temperature insulation, dielectrics, bearings, seals, thrust washers, and pump impellers/diffusers. Advances were also made in thermal management of electric motors. In addition to the overall system design for a full-scale EGS application, a subscale prototype was designed and fabricated. Like the full-scale design, the subscale prototype features a novel “flow-through-the-bore” permanent magnet electric motor that combines the use of high temperature materials with an internal cooling scheme that limits peak internal temperatures to <330°C. While the full-scale high-volume multi-stage pump is designed to lift up to 80 kg/s of process water, the subscale prototype is based on a production design that can pump 20 kg/s and has been modified

  1. Internal Electrostatic Discharge Monitor - IESDM

    NASA Technical Reports Server (NTRS)

    Kim, Wousik; Goebel, Dan M.; Jun, Insoo; Garrett, Henry B.

    2011-01-01

    A document discusses an innovation designed to effectively monitor dielectric charging in spacecraft components to measure the potential for discharge in order to prevent damage from internal electrostatic discharge (IESD). High-energy electrons penetrate the structural materials and shielding of a spacecraft and then stop inside dielectrics and keep accumulating. Those deposited charges generate an electric field. If the electric field becomes higher than the breakdown threshold (approx. =2 x 10(exp 5) V/cm), discharge occurs. This monitor measures potentials as a function of dielectric depth. Differentiation of potential with respect to the depth yields electric field. Direct measurement of the depth profile of the potential in a dielectric makes real-time electronic field evaluation possible without simulations. The IESDM has been designed to emulate a multi-layer circuit board, to insert very thin metallic layers between the dielectric layers. The conductors serve as diagnostic monitoring locations to measure the deposited electron-charge and the charge dynamics. Measurement of the time-dependent potential of the metal layers provides information on the amount of charge deposited in the dielectrics and the movement of that charge with time (dynamics).

  2. Micromachined, Electrostatically Deformable Reflectors

    NASA Technical Reports Server (NTRS)

    Bartman, Randall K.; Wang, Paul K. C.; Miller, Linda M.; Kenny, Thomas W.; Kaiser, William J.; Hadaegh, Fred Y.; Agronin, Michael L.

    1995-01-01

    Micromachined, closed-loop, electrostatically actuated reflectors (microCLEARs) provide relatively simple and inexpensive alternatives to large, complex, expensive adaptive optics used to control wavefronts of beams of light in astronomy and in experimental laser weapons. Micromachining used to make deformable mirror, supporting structure, and actuation circuitry. Development of microCLEARs may not only overcome some of disadvantages and limitations of older adaptive optics but may also satisfy demands of potential market for small, inexpensive deformable mirrors in electronically controlled film cameras, video cameras, and other commercial optoelectronic instruments.

  3. Electrostatically Driven Nanoballoon Actuator.

    PubMed

    Barzegar, Hamid Reza; Yan, Aiming; Coh, Sinisa; Gracia-Espino, Eduardo; Dunn, Gabriel; Wågberg, Thomas; Louie, Steven G; Cohen, Marvin L; Zettl, Alex

    2016-11-09

    We demonstrate an inflatable nanoballoon actuator based on geometrical transitions between the inflated (cylindrical) and collapsed (flattened) forms of a carbon nanotube. In situ transmission electron microscopy experiments employing a nanoelectromechanical manipulator show that a collapsed carbon nanotube can be reinflated by electrically charging the nanotube, thus realizing an electrostatically driven nanoballoon actuator. We find that the tube actuator can be reliably cycled with only modest control voltages (few volts) with no apparent wear or fatigue. A complementary theoretical analysis identifies critical parameters for nanotube nanoballoon actuation.

  4. Electrostatic Return of Contaminants

    NASA Technical Reports Server (NTRS)

    Rantanen, R.; Gordon, T.

    2003-01-01

    A Model has been developed capable of calculating the electrostatic return of spacecraft-emitted molecules that are ionized and attracted back to the spacecraft by the spacecraft electric potential on its surfaces. The return of ionized contaminant molecules to charged spacecraft surfaces is very important to all altitudes. It is especially important at geosynchronous and interplanetary environments, since it may be the only mechanism by which contaminants can degrade a surface. This model is applicable to all altitudes and spacecraft geometries. In addition to results of the model will be completed to cover a wide range of potential space systems.

  5. Electrostatic properties of fullerenes under an external electric field: First-principles calculations of energetics for all IPR isomers from C60 to C78

    NASA Astrophysics Data System (ADS)

    Sorimachi, Jun-ya; Okada, Susumu

    2016-08-01

    Based on first-principles total energy calculations, we analyze the energetics of the fullerene isomers from C60 to C78, all of which satisfy the isolated pentagon rule, under a parallel electric field. Our calculations show that the total energy of the fullerene is proportional to the square of the external electric field. On the other hand, the coefficient of the quadratic energy profile is sensitive to the fullerene species and their orientation. Furthermore, fullerenes possessing lower symmetry exhibit asymmetric quadratic energy profiles with respect to the field, indicating that they possess intrinsic polarization along particular molecular orientations.

  6. Coarsening in high volume fraction nickel-base alloys

    NASA Technical Reports Server (NTRS)

    Mackay, R. A.; Nathal, M. V.

    1990-01-01

    The coarsening behavior of the gamma-prime precipitate has been examined in high volume fraction nickel-base alloys aged at elevated temperatures for times of up to 5000 h. Although the cube rate law was observed during coarsening, none of the presently available coarsening theories showed complete agreement with the experimental particle size distributions (PSDs). These discrepancies were thought to be due to elastic coherency strains which were not considered by the available models. Increasing the Mo content significantly influenced the PSDs and decreased the coarsening rate of the gamma-prime cubes, as a result of increasing the magnitude of the lattice mismatch. After extended aging times, the gamma-prime cubes underwent massive coalescence into plates at a rate which was much faster than the cuboidal coarsening rate. Once the gamma-prime plates were formed, further coarsening was not observed, and this stabilization of the microstructure was attributed to the development of dislocation networks at the gamma-gamma-prime interfaces.

  7. NIL defect performance toward high volume mass production

    NASA Astrophysics Data System (ADS)

    Hatano, Masayuki; Kobayashi, Kei; Kashiwagi, Hiroyuki; Tokue, Hiroshi; Kono, Takuya; Tetsuro, Nakasugi; Choi, Eun Hyuk; Jung, Wooyung

    2016-03-01

    A low cost alternative lithographic technology is desired to meet with the decreasing feature size of semiconductor devices. Nanoimprint lithography (NIL) is one of the candidates for alternative lithographic technologies. NIL has advantages such as good resolution, critical dimension (CD) uniformity and smaller line edge roughness (LER). 4 On the other hand, NIL involves some risks. Defectivity is the most critical issue in NIL. The progress in the defect reduction on templates shows great improvement recently. In other words, the defect reduction of the NIIL process is a key to apply NIL to mass production. In this paper, we describe the evaluation results of the defect performance of NIL using an up-to-date tool, Canon FPA-1100 NZ2, and discuss the future potential of NIL in terms of defectivity. The impact of various kinds defects, such as the non-filling defect, plug defect, line collapse, and defects on replica templates are discussed. We found that non-fill defects under the resist pattern cause line collapse. It is important to prevent line collapse. From these analyses based on actual NIL defect data on long-run stability, we will show the way to reduce defects and the possibility of NIL in device high volume mass production. For the past one year, we have been are collaborating with SK Hynix to bring this promising technology into mainstream manufacturing. This work is the result of this collaboration.

  8. Radiation safety audit of a high volume Nuclear Medicine Department.

    PubMed

    Jha, Ashish Kumar; Singh, Abhijith Mohan; Shetye, Bhakti; Shah, Sneha; Agrawal, Archi; Purandare, Nilendu Chandrakant; Monteiro, Priya; Rangarajan, Venkatesh

    2014-10-01

    Professional radiation exposure cannot be avoided in nuclear medicine practices. It can only be minimized up to some extent by implementing good work practices. The aim of our study was to audit the professional radiation exposure and exposure rate of radiation worker working in and around Department of nuclear medicine and molecular imaging, Tata Memorial Hospital. We calculated the total number of nuclear medicine and positron emission tomography/computed tomography (PET/CT) procedures performed in our department and the radiation exposure to the radiation professionals from year 2009 to 2012. We performed an average of 6478 PET/CT scans and 3856 nuclear medicine scans/year from January 2009 to December 2012. The average annual whole body radiation exposure to nuclear medicine physician, technologist and nursing staff are 1.74 mSv, 2.93 mSv and 4.03 mSv respectively. Efficient management and deployment of personnel is of utmost importance to optimize radiation exposure in a high volume nuclear medicine setup in order to work without anxiety of high radiation exposure.

  9. PTA proves its worth in high-volume hardfacing jobs

    SciTech Connect

    Raghu, D.; Webber, R.

    1996-02-01

    Imparting wear and corrosion resistance to metal surfaces by providing a hard surface is the basis for hardfacing. The realization of the economic advantage of increased wear by providing a metal deposit on a relatively low-cost substrate has spurred the growth of hardfacing over the last half century. Plasma transferred arc (PTA) hardfacing and laser beam hardfacing are relative newcomers to this arena. Hardfacing with PTA is ideal for high-volume hardfacing where a high degree of quality, reliability and consistency is required. Significant advances in materials and equipment have helped to spur the advancement of the technology and the wider acceptance by industry. It is believed that in the future, PTA hardfacing systems will be developed that rely a great deal on microprocessors and robotics, more so than at present. These would further enhance the product quality and consistency and would enable tailor-made PTA system designs for multiple applications. The quest for new materials for PTA hardfacing that combine wear and corrosion resistance and weldability is expected to continue. Newer applications are constantly being developed as more and more medium- and small-scale operators realize the advantages that can be derived from the use of PTA hardfacing. The basic driving force for these improvements and growth is quality, reliability, productivity and significant long-term cost reduction.

  10. Radiation safety audit of a high volume Nuclear Medicine Department

    PubMed Central

    Jha, Ashish Kumar; Singh, Abhijith Mohan; Shetye, Bhakti; Shah, Sneha; Agrawal, Archi; Purandare, Nilendu Chandrakant; Monteiro, Priya; Rangarajan, Venkatesh

    2014-01-01

    Introduction: Professional radiation exposure cannot be avoided in nuclear medicine practices. It can only be minimized up to some extent by implementing good work practices. Aim and Objectives: The aim of our study was to audit the professional radiation exposure and exposure rate of radiation worker working in and around Department of nuclear medicine and molecular imaging, Tata Memorial Hospital. Materials and Methods: We calculated the total number of nuclear medicine and positron emission tomography/computed tomography (PET/CT) procedures performed in our department and the radiation exposure to the radiation professionals from year 2009 to 2012. Results: We performed an average of 6478 PET/CT scans and 3856 nuclear medicine scans/year from January 2009 to December 2012. The average annual whole body radiation exposure to nuclear medicine physician, technologist and nursing staff are 1.74 mSv, 2.93 mSv and 4.03 mSv respectively. Conclusion: Efficient management and deployment of personnel is of utmost importance to optimize radiation exposure in a high volume nuclear medicine setup in order to work without anxiety of high radiation exposure. PMID:25400361

  11. Electrostatic Beneficiation of Coal

    SciTech Connect

    D. Lindquist; K. B. Tennal; M. K. Mazumder

    1998-10-29

    It was suggested in the proposal that small particles, due to low inertia, may not impact on the surfaces of the tribocharger. They would, thus, not receive charge and would not be beneficiated in the electrostatic separation. A milling process was proposed in which the small particles are stirred together with larger carrier beads producing the desired contact charge exchange. A force is necessary for removing the coal particles from the carrier beads. In copying machines electrostatic force is used to pull toner particles away horn iron carrier particles which are held back by magnetic force. Aerodynamic force is used in test instruments for measuring the charge to mass ratio on toners. A similar system of milling and removal is desired for use with the small coal particles. The carrier beads need to be made of copper rather than iron. This complicates the separation process since copper is non-magnetic. We are working on coating of iron beads with a layer of copper. Dr. Robert Engleken of Arkansas State University has supplied us with several test batches of copper-coated iron in the size range of -40 +70 mesh. ` We are currently testing whether the milling process used with the copper coated iron beads produces the desired charge on the coal particles.

  12. Undamped electrostatic plasma waves

    SciTech Connect

    Valentini, F.; Perrone, D.; Veltri, P.; Califano, F.; Pegoraro, F.; Morrison, P. J.; O'Neil, T. M.

    2012-09-15

    Electrostatic waves in a collision-free unmagnetized plasma of electrons with fixed ions are investigated for electron equilibrium velocity distribution functions that deviate slightly from Maxwellian. Of interest are undamped waves that are the small amplitude limit of nonlinear excitations, such as electron acoustic waves (EAWs). A deviation consisting of a small plateau, a region with zero velocity derivative over a width that is a very small fraction of the electron thermal speed, is shown to give rise to new undamped modes, which here are named corner modes. The presence of the plateau turns off Landau damping and allows oscillations with phase speeds within the plateau. These undamped waves are obtained in a wide region of the (k,{omega}{sub R}) plane ({omega}{sub R} being the real part of the wave frequency and k the wavenumber), away from the well-known 'thumb curve' for Langmuir waves and EAWs based on the Maxwellian. Results of nonlinear Vlasov-Poisson simulations that corroborate the existence of these modes are described. It is also shown that deviations caused by fattening the tail of the distribution shift roots off of the thumb curve toward lower k-values and chopping the tail shifts them toward higher k-values. In addition, a rule of thumb is obtained for assessing how the existence of a plateau shifts roots off of the thumb curve. Suggestions are made for interpreting experimental observations of electrostatic waves, such as recent ones in nonneutral plasmas.

  13. Electrostatic Plasma Accelerator (EPA)

    NASA Technical Reports Server (NTRS)

    Brophy, John R.; Aston, Graeme

    1995-01-01

    The application of electric propulsion to communications satellites, however, has been limited to the use of hydrazine thrusters with electric heaters for thrust and specific impulse augmentation. These electrothermal thrusters operate at specific impulse levels of approximately 300 s with heater powers of about 500 W. Low power arcjets (1-3 kW) are currently being investigated as a way to increase specific impulse levels to approximately 500 s. Ion propulsion systems can easily produce specific impulses of 3000 s or greater, but have yet to be applied to communications satellites. The reasons most often given for not using ion propulsion systems are their high level of overall complexity, low thrust with long burn times, and the difficulty of integrating the propulsion system into existing commercial spacecraft busses. The Electrostatic Plasma Accelerator (EPA) is a thruster concept which promises specific impulse levels between low power arcjets and those of the ion engine while retaining the relative simplicity of the arcjet. The EPA thruster produces thrust through the electrostatic acceleration of a moderately dense plasma. No accelerating electrodes are used and the specific impulse is a direct function of the applied discharge voltage and the propellant atomic mass.

  14. Electrostatic Plasma Accelerator (EPA)

    NASA Technical Reports Server (NTRS)

    Brophy, John R.; Aston, Graeme

    1995-01-01

    The application of electric propulsion to communications satellites, however, has been limited to the use of hydrazine thrusters with electric heaters for thrust and specific impulse augmentation. These electrothermal thrusters operate at specific impulse levels of approximately 300 s with heater powers of about 500 W. Low power arcjets (1-3 kW) are currently being investigated as a way to increase specific impulse levels to approximately 500 s. Ion propulsion systems can easily produce specific impulses of 3000 s or greater, but have yet to be applied to communications satellites. The reasons most often given for not using ion propulsion systems are their high level of overall complexity, low thrust with long burn times, and the difficulty of integrating the propulsion system into existing commercial spacecraft busses. The Electrostatic Plasma Accelerator (EPA) is a thruster concept which promises specific impulse levels between low power arcjets and those of the ion engine while retaining the relative simplicity of the arcjet. The EPA thruster produces thrust through the electrostatic acceleration of a moderately dense plasma. No accelerating electrodes are used and the specific impulse is a direct function of the applied discharge voltage and the propellant atomic mass.

  15. Investigation of Electrostatic Accelerometer in HUST for Space Science Missions

    NASA Astrophysics Data System (ADS)

    Bai, Yanzheng; Hu, Ming; Li, Gui; Liu, Li; Qu, Shaobo; Wu, Shuchao; Zhou, Zebing

    2014-05-01

    High-precision electrostatic accelerometers are significant payload in CHAMP, GRACE and GOCE gravity missions to measure the non-gravitational forces. In our group, space electrostatic accelerometer and inertial sensor based on the capacitive sensors and electrostatic control technique has been investigated for space science research in China such as testing of equivalence principle (TEPO), searching non-Newtonian force in micrometer range, satellite Earth's field recovery and so on. In our group, a capacitive position sensor with a resolution of 10-7pF/Hz1/2 and the μV/Hz1/2 level electrostatic actuator are developed. The fiber torsion pendulum facility is adopt to measure the parameters of the electrostatic controlled inertial sensor such as the resolution, and the electrostatic stiffness, the cross couple between different DOFs. Meanwhile, high voltage suspension and free fall methods are applied to verify the function of electrostatic accelerometer. Last, the engineering model of electrostatic accelerometer has been developed and tested successfully in space and preliminary results are present.

  16. Electrostatic separation of brass from industrial wastes

    SciTech Connect

    Iuga, A.; Morar, R.; Samuila, A.; Mihailescu, M.; Cuglesan, I.; Dascalescu, L.

    1999-05-01

    Previous studies have demonstrated that electrostatic separation can be successfully employed for the recycling of nonferrous metals from chopped electric wire and cable scrap. The aim of this paper was to investigate the possibility of using the electric field forces for the selective sorting of other granular mixtures, such as brass dross. Laboratory tests of electrostatic separation were carried out on three samples: 0.08--1 mm, 0.08--0.2 mm, and 0.2--1 mm, containing more than 66% of brass. Sample 1 was separated in a corona-electrostatic field, generated by a standard electrode arrangement: a grounded rotating roll electrode (diameter 150 mm) and two high-voltage electrodes (wire-type dual corona electrode + tubular electrode). Processing of the other two samples was carried out in a custom-designed separator comprising an extended corona field generated between a matrix-type multineedle corona electrode and a roll electrode of large diameter (250 mm). Chemical analysis of the products showed that more than 90% of the brass can be recovered with a purity higher than 95%. The extended corona field electrode arrangement proposed in this paper seems to be a promising solution for the effective recycling of other granular wastes containing copper, aluminum, and their alloys.

  17. Electrostatic 'bounce' instability in a magnetotail configuration

    SciTech Connect

    Fruit, G.; Louarn, P.; Tur, A.

    2013-02-15

    To understand the possible destabilization of two-dimensional current sheets, a kinetic model is proposed to describe the resonant interaction between electrostatic modes and trapped particles that bounce within the sheet. This work follows the initial investigation by Tur et al.[Phys. Plasmas 17, 102905 (2010)] that is revised and extended. Using a quasi-parabolic equilibrium state, the linearized gyro-kinetic Vlasov equation is solved for electrostatic fluctuations with period of the order of the electron bounce period. Using an appropriated Fourier expansion of the particle motion along the magnetic field, the complete time integration of the non-local perturbed distribution functions is performed. The dispersion relation for electrostatic modes is then obtained through the quasineutrality condition. It is found that strongly unstable electrostatic modes may develop provided that the current sheet is moderately stretched and, more important, that the proportion of passing particle remains small (less than typically 10%). This strong but finely tuned instability may offer opportunities to explain features of magnetospheric substorms.

  18. Electrostatics of Pharmaceutical Aerosols for Pulmonary Delivery.

    PubMed

    Lip Kwok, Philip Chi

    2015-01-01

    This paper provides a review on key research findings in the rapidly developing area of pharmaceutical aerosol electrostatics. Solids and liquids can become charged without electric fields, the former by contact or friction and the latter by flowing or spraying. Therefore, charged particles and droplets carrying net charges are produced from pharmaceutical inhalers (e.g. dry powder inhalers, metered dose inhalers, and nebulisers) due to the mechanical processes involved in aerosolisation. The charging depends on many physicochemical factors, such as formulation composition, solid state properties, inhaler material and design, and relative humidity. In silico, in vitro, and limited in vivo studies have shown that electrostatic charges may potentially influence particle deposition in the airways. However, the evidence is not yet conclusive. Furthermore, there are currently no regulatory requirements on the characterisation and control of the electrostatic properties of inhaled formulations. Besides the need for further investigations on the relationship between physicochemical factors and charging characteristics of the aerosols, controlled and detailed in vivo studies are also required to confirm whether charges can affect particle deposition in the airways. Since pharmaceutical aerosol electrostatics is a relatively new research area, much remains to be explored. Thus there is certainly potential for development. New findings in the future may contribute to the advancement of pharmaceutical aerosol formulations and respiratory drug delivery.

  19. Hybrid CD metrology concept compatible with high-volume manufacturing

    NASA Astrophysics Data System (ADS)

    Foucher, J.; Faurie, P.; Dourthe, L.; Irmer, B.; Penzkofer, C.

    2011-03-01

    The measurement uncertainty is becoming one of the major components that have to be controlled in order to guarantee sufficient production yield. Already at the R&D level, we have to cope up with the accurate measurements of sub-40nm dense trenches and contact holes coming from 193 immersion lithography or E-Beam lithography. Current production CD metrology techniques such as CD-SEM and OCD are limited in relative accuracy for various reasons (i.e electron proximity effect, outputs parameters correlation, stack influence, electron interaction with materials...). Therefore, time for R&D is increasing, process windows degrade and finally production yield can decrease because you can not manufactured correctly if you are unable to measure correctly. A new high volume manufacturing (HVM) CD metrology solution has to be found in order to improve the relative accuracy of production environment otherwise current CD Metrology solution will very soon get out of steam. In this paper, we will present a potential Hybrid CD metrology solution that smartly tuned 3D-AFM and CD-SEM data in order to add accuracy both in R&D and production. The final goal for "chip makers" is to improve yield and save R&D and production costs through real-time feedback loop implement on CD metrology routines. Such solution can be implemented and extended to any kind of CD metrology solution. In a 2nd part we will discuss and present results regarding a new AFM3D probes breakthrough with the introduction of full carbon tips made will E-Beam Deposition process. The goal is to overcome the current limitations of conventional flared silicon tips which are definitely not suitable for sub-32nm nodes production.

  20. Radiological and material characterization of high volume fly ash concrete.

    PubMed

    Ignjatović, I; Sas, Z; Dragaš, J; Somlai, J; Kovács, T

    2017-03-01

    The main goal of research presented in this paper was the material and radiological characterization of high volume fly ash concrete (HVFAC) in terms of determination of natural radionuclide content and radon emanation and exhalation coefficients. All concrete samples were made with a fly ash content between 50% and 70% of the total amount of cementitious materials from one coal burning power plant in Serbia. Physical (fresh and hardened concrete density) and mechanical properties (compressive strength, splitting tensile strength and modulus of elasticity) of concrete were tested. The radionuclide content ((226)Ra, (232)Th and (40)K) and radon massic exhalation of HVFAC samples were determined using gamma spectrometry. Determination of massic exhalation rates of HVFAC and its components using radon accumulation chamber techniques combined with a radon monitor was performed. The results show a beneficial effect of pozzolanic activity since the increase in fly ash content resulted in an increase in compressive strength of HVFAC by approximately 20% for the same mass of cement used in the mixtures. On the basis of the obtained radionuclide content of concrete components the I -indices of different HVFAC samples were calculated and compared with measured values (0.27-0.32), which were significantly below the recommended 1.0 index value. The prediction was relatively close to the measured values as the ratio between the calculated and measured I-index ranged between 0.89 and 1.14. Collected results of mechanical and radiological properties and performed calculations clearly prove that all 10 designed concretes with a certain type of fly ash are suitable for structural and non-structural applications both from a material and radiological point of view.

  1. Process window limiting hot spot monitoring for high-volume manufacturing

    NASA Astrophysics Data System (ADS)

    Jochemsen, Marinus; Anunciado, Roy; Timoshkov, Vadim; Hunsche, Stefan; Zhou, Xinjian; Jones, Chris; Callan, Neal

    2016-03-01

    As process window margins for cutting edge DUV lithography continue to shrink, the impact of systematic patterning defects on final yield increases. Finding process window limiting hot spot patterns and monitoring them in high volume manufacturing (HVM) is increasingly challenging with conventional methods, as the size of critical defects can be below the resolution of traditional HVM inspection tools. We utilize a previously presented computational method of finding hot spot patterns by full chip simulation and use this to guide high resolution review tools by predicting the state of the hot spots on all fields of production wafers. In experiments with a 10nm node Metal LELELE vehicle we show a 60% capture rate of after-etch defects down to 3nm in size, at specific hot spot locations. By using the lithographic focus and dose correction knobs we can reduce the number of patterning defects for this test case by ~60%.

  2. Electrostatic quadrupole DC accelerators for BNCT applications

    SciTech Connect

    Kwan, J.W.; Anderson, O.A.; Reginato, L.L.; Vella, M.C.; Yu, S.S.

    1994-04-01

    A dc electrostatic quadrupole (ESQ) accelerator is capable of producing a 2.5 MeV, 100 mA proton beam for the purpose of generating neutrons for Boron Neutron Capture Therapy. The ESQ accelerator is better than the conventional aperture column in high beam current application due to the presence of stronger transverse field for beam focusing and for suppressing secondary electrons. The major challenge in this type of accelerator is in developing the proper power supply system.

  3. Electrostatic and whistler instabilities excited by an electron beam

    NASA Astrophysics Data System (ADS)

    An, Xin; Bortnik, Jacob; Van Compernolle, Bart; Decyk, Viktor; Thorne, Richard

    2017-07-01

    The electron beam-plasma system is ubiquitous in the space plasma environment. Here, using a Darwin particle-in-cell method, the excitation of electrostatic and whistler instabilities by a gyrating electron beam is studied in support of recent laboratory experiments. It is assumed that the total plasma frequency (ωpe) is larger than the electron cyclotron frequency (Ωe). The fast-growing electrostatic beam-mode waves saturate in a few plasma oscillations by slowing down and relaxing the electron beam parallel to the background magnetic field. Upon their saturation, the finite amplitude electrostatic beam-mode waves can resonate with the tail of the background thermal electrons and accelerate them to the beam parallel velocity. The slower-growing whistler waves are excited in primarily two resonance modes: (a) through Landau resonance due to the inverted slope of the beam electrons in the parallel velocity and (b) through cyclotron resonance by scattering electrons to both lower pitch angles and smaller energies. It is demonstrated that, for a field-aligned beam, the whistler instability can be suppressed by the electrostatic instability due to a faster energy transfer rate between the beam electrons and electrostatic waves. Such a competition of growth between whistler and electrostatic waves depends on the ratio of ωpe/Ωe. In terms of wave propagation, beam-generated electrostatic waves are confined to the beam region, whereas beam-generated whistler waves transport energy away from the beam.

  4. Miniature Bipolar Electrostatic Ion Thruster

    NASA Technical Reports Server (NTRS)

    Hartley, Frank T.

    2006-01-01

    The figure presents a concept of a bipolar miniature electrostatic ion thruster for maneuvering a small spacecraft. The ionization device in the proposed thruster would be a 0.1-micron-thick dielectric membrane with metal electrodes on both sides. Small conical holes would be micromachined through the membrane and electrodes. An electric potential of the order of a volt applied between the membrane electrodes would give rise to an electric field of the order of several mega-volts per meter in the submicron gap between the electrodes. An electric field of this magnitude would be sufficient to ionize all the molecules that enter the holes. In a thruster-based on this concept, one or more propellant gases would be introduced into such a membrane ionizer. Unlike in larger prior ion thrusters, all of the propellant molecules would be ionized. This thruster would be capable of bipolar operation. There would be two accelerator grids - one located forward and one located aft of the membrane ionizer. In one mode of operation, which one could denote the forward mode, positive ions leaving the ionizer on the backside would be accelerated to high momentum by an electric field between the ionizer and an accelerator grid. Electrons leaving the ionizer on the front side would be ejected into free space by a smaller accelerating field. The equality of the ion and electron currents would eliminate the need for an additional electron- or ion-emitting device to keep the spacecraft charge-neutral. In another mode of operation, which could denote the reverse mode, the polarities of the voltages applied to the accelerator grids and to the electrodes of the membrane ionizer would be the reverse of those of the forward mode. The reversal of electric fields would cause the ion and electrons to be ejected in the reverse of their forward mode directions, thereby giving rise to thrust in the direction opposite that of the forward mode.

  5. ELECTROSTATIC MEMORY SYSTEM

    DOEpatents

    Chu, J.C.

    1958-09-23

    An improved electrostatic memory system is de scribed fer a digital computer wherein a plarality of storage tubes are adapted to operate in either of two possible modes. According to the present irvention, duplicate storage tubes are provided fur each denominational order of the several binary digits. A single discriminator system is provided between corresponding duplicate tubes to determine the character of the infurmation stored in each. If either tube produces the selected type signal, corresponding to binazy "1" in the preferred embodiment, a "1" is regenerated in both tubes. In one mode of operation each bit of information is stored in two corresponding tubes, while in the other mode of operation each bit is stored in only one tube in the conventional manner.

  6. MEMS electrostatic influence machines

    NASA Astrophysics Data System (ADS)

    Phu Le, Cuong; Halvorsen, Einar

    2016-11-01

    This paper analyses the possibility of MEMS electrostatic influence machines using electromechanical switches like the historical predecessors did two centuries ago. We find that a generator design relying entirely on standard silicon-on-insulator(SOI) micromachining is conceivable and analyze its performance by simulations. The concept appears preferable over comparable diode circuits due to its higher maximum energy, faster charging and low precharging voltage. A full electromechanical lumped-model including parasitic capacitances of the switches is built to capture the dynamic of the generator. Simulation results show that the output voltage can be exponentially bootstrapped from a very low precharging voltage so that otherwise inadequately small voltage differences or charge imbalances can be made useful.

  7. Electrostatic trapping of ammonia molecules

    PubMed

    Bethlem; Berden; Crompvoets; Jongma; van Roij AJ; Meijer

    2000-08-03

    The ability to cool and slow atoms with light for subsequent trapping allows investigations of the properties and interactions of the trapped atoms in unprecedented detail. By contrast, the complex structure of molecules prohibits this type of manipulation, but magnetic trapping of calcium hydride molecules thermalized in ultra-cold buffer gas and optical trapping of caesium dimers generated from ultra-cold caesium atoms have been reported. However, these methods depend on the target molecules being paramagnetic or able to form through the association of atoms amenable to laser cooling, respectively, thus restricting the range of species that can be studied. Here we describe the slowing of an adiabatically cooled beam of deuterated ammonia molecules by time-varying inhomogeneous electric fields and subsequent loading into an electrostatic trap. We are able to trap state-selected ammonia molecules with a density of 10(6) cm(-3) in a volume of 0.25 cm3 at temperatures below 0.35 K. We observe pronounced density oscillations caused by the rapid switching of the electric fields during loading of the trap. Our findings illustrate that polar molecules can be efficiently cooled and trapped, thus providing an opportunity to study collisions and collective quantum effects in a wide range of ultra-cold molecular systems.

  8. Reintroducing Electrostatics into Macromolecular Crystallographic Refinement: Application to Neutron Crystallography and DNA Hydration

    PubMed Central

    Fenn, Timothy D.; Schnieders, Michael J.; Mustyakimov, Marat; Wu, Chuanjie; Langan, Paul; Pande, Vijay S.; Brunger, Axel T.

    2011-01-01

    Summary Most current crystallographic structure refinements augment the diffraction data with a priori information consisting of bond, angle, dihedral, planarity restraints and atomic repulsion based on the Pauli exclusion principle. Yet, electrostatics and van der Waals attraction are physical forces that provide additional a priori information. Here we assess the inclusion of electrostatics for the force field used for all-atom (including hydrogen) joint neutron/X-ray refinement. Two DNA and a protein crystal structure were refined against joint neutron/X-ray diffraction data sets using force fields without electrostatics or with electrostatics. Hydrogen bond orientation/geometry favors the inclusion of electrostatics. Refinement of Z-DNA with electrostatics leads to a hypothesis for the entropic stabilization of Z-DNA that may partly explain the thermodynamics of converting the B form of DNA to its Z form. Thus, inclusion of electrostatics assists joint neutron/X-ray refinements, especially for placing and orienting hydrogen atoms. PMID:21481775

  9. Electrostatic capacitance and Faraday cage behavior of carbon nanotube forests

    SciTech Connect

    Ya'akobovitz, A.; Bedewy, M.; Hart, A. J.

    2015-02-02

    Understanding of the electrostatic properties of carbon nanotube (CNT) forests is essential to enable their integration in microelectronic and micromechanical devices. In this study, we sought to understand how the hierarchical geometry and morphology of CNT forests determines their capacitance. First, we find that at small gaps, solid micropillars have greater capacitance, yet at larger gaps the capacitance of the CNT forests is greater. The surface area of the CNT forest accessible to the electrostatic field was extracted by analysis of the measured capacitance, and, by relating the capacitance to the average density of CNTs in the forest, we find that the penetration depth of the electrostatic field is on the order of several microns. Therefore, CNT forests can behave as a miniature Faraday cage. The unique electrostatic properties of CNT forests could therefore enable their use as long-range proximity sensors and as shielding elements for miniature electronic devices.

  10. Fabrication of perovskite films using an electrostatic assisted spray technique: the effect of the electric field on morphology, crystallinity and solar cell performance

    NASA Astrophysics Data System (ADS)

    Chandrasekhar, P. S.; Kumar, Neetesh; Swami, Sanjay Kumar; Dutta, V.; Komarala, Vamsi K.

    2016-03-01

    An electric field assisted spray deposition method is employed for improving the perovskite film morphology, crystallinity, and surface coverage, and for further fabricating an efficient solar cell. By applying different voltages ranging from 0.5 to 2.0 kV during spray deposition, we observed a large variation in the film morphology and surface coverage compared to those fabricated without an electric field, which is due to improved atomization from the Coulomb fission process. The optimized applied voltage of 1.5 kV during spraying led to completion of the reaction between CH3NH3I and PbI2 on a hot substrate for pure phase CH3NH3PbI3 thin film formation with improved grain growth and surface coverage. The cells fabricated using perovskite films showed clear applied voltage dependence in the energy conversion process and alleviation in J-V hysteresis; with 1.5 kV applied voltage the average cell efficiency of 8.9% was obtained compared to films fabricated without applying voltage providing only 6.5%. The best efficiencies are 10.9% and 7.37% for applied voltages of 1.5 kV and 0 kV, respectively. The enhancement in efficiency with applied voltage is due to the formation of more uniform and dense films with large perovskite crystals, which resulted in efficient electron transportation (enhanced photocurrent and modified series and shunt resistances) by minimizing the charge carrier recombination at grain boundaries (resulting in enhanced open circuit voltage). With further optimization of the perovskite film thickness by adjusting the CH3NH3I spray volume, the average cell efficiency of ~11.0% was obtained.An electric field assisted spray deposition method is employed for improving the perovskite film morphology, crystallinity, and surface coverage, and for further fabricating an efficient solar cell. By applying different voltages ranging from 0.5 to 2.0 kV during spray deposition, we observed a large variation in the film morphology and surface coverage compared to

  11. Fabrication of perovskite films using an electrostatic assisted spray technique: the effect of the electric field on morphology, crystallinity and solar cell performance.

    PubMed

    Chandrasekhar, P S; Kumar, Neetesh; Swami, Sanjay Kumar; Dutta, V; Komarala, Vamsi K

    2016-03-28

    An electric field assisted spray deposition method is employed for improving the perovskite film morphology, crystallinity, and surface coverage, and for further fabricating an efficient solar cell. By applying different voltages ranging from 0.5 to 2.0 kV during spray deposition, we observed a large variation in the film morphology and surface coverage compared to those fabricated without an electric field, which is due to improved atomization from the Coulomb fission process. The optimized applied voltage of 1.5 kV during spraying led to completion of the reaction between CH3NH3I and PbI2 on a hot substrate for pure phase CH3NH3PbI3 thin film formation with improved grain growth and surface coverage. The cells fabricated using perovskite films showed clear applied voltage dependence in the energy conversion process and alleviation in J-V hysteresis; with 1.5 kV applied voltage the average cell efficiency of 8.9% was obtained compared to films fabricated without applying voltage providing only 6.5%. The best efficiencies are 10.9% and 7.37% for applied voltages of 1.5 kV and 0 kV, respectively. The enhancement in efficiency with applied voltage is due to the formation of more uniform and dense films with large perovskite crystals, which resulted in efficient electron transportation (enhanced photocurrent and modified series and shunt resistances) by minimizing the charge carrier recombination at grain boundaries (resulting in enhanced open circuit voltage). With further optimization of the perovskite film thickness by adjusting the CH3NH3I spray volume, the average cell efficiency of ∼11.0% was obtained.

  12. Racial disparities in changing to a high-volume urologist among men with localized prostate cancer

    PubMed Central

    Pollack, Craig Evan; Bekelman, Justin; Epstein, Andrew J; Liao, KJ; Wong, Yu-Ning; Armstrong, Katrina

    2011-01-01

    Background Though patients who receive surgery from high-volume surgeons tend to have better outcomes, black patients are less likely to receive surgery from high-volume surgeons. Objective Among men with localized prostate cancer, we examined whether disparities in use of high-volume urologists resulted from racial differences in patients being diagnosed by high-volume urologists and/or changing to high-volume urologists for surgery. Research Design Retrospective cohort study from Surveillance, Epidemiology, and End Results-Medicare data Subjects 26,058 black and white men in SEER-Medicare diagnosed with localized prostate cancer from 1995 to 2005 that underwent prostatectomy. Patients were linked to their diagnosing urologist and a treating urologist (who performed the surgery). Measures Diagnosis and receipt of prostatectomy by a high-volume urologist, and changing between diagnosing and treating urologist Results After adjustment for confounders, black men were as likely as white men to be diagnosed by a high-volume urologist; however, they were significantly less likely than white men to be treated by a high-volume urologist (Odds ratio 0.76, 95% Confidence Interval [CI] 0.67, 0.87). For men diagnosed by a low-volume urologist, 46.0% changed urologists for their surgery. Black men were significantly less likely to change to a high-volume urologist (Relative Risk Ratio 0.61, 95%CI 0.47, 0.79). Racial differences appeared to reflect black and white patients being diagnosed by different urologists and having different rates of changing after being diagnosed by the same urologists. Conclusions Lower rates of changing to high-volume urologists for surgery among black men contribute to racial disparities in treatment by high-volume surgeons. PMID:22005606

  13. Electrostatic trapping of metastable NH molecules

    SciTech Connect

    Hoekstra, Steven; Metsaelae, Markus; Zieger, Peter C.; Scharfenberg, Ludwig; Gilijamse, Joop J.; Meijer, Gerard; Meerakker, Sebastiaan Y. T. van de

    2007-12-15

    We report on the Stark deceleration and electrostatic trapping of {sup 14}NH (a{sup 1}{delta}) radicals. In the trap, the molecules are excited on the spin-forbidden A{sup 3}{pi}<-a{sup 1}{delta} transition and detected via their subsequent fluorescence to the X{sup 3}{sigma}{sup -} ground state. The 1/e trapping time is 1.4{+-}0.1 s, from which a lower limit of 2.7 s for the radiative lifetime of the a{sup 1}{delta}, v=0, J=2 state is deduced. The spectral profile of the molecules in the trapping field is measured to probe their spatial distribution. Electrostatic trapping of metastable NH followed by optical pumping of the trapped molecules to the electronic ground state is an important step toward accumulation of these radicals in a magnetic trap.

  14. Ultrafast collisional ion heating by electrostatic shocks

    PubMed Central

    Turrell, A. E.; Sherlock, M.; Rose, S. J.

    2015-01-01

    High-intensity lasers can be used to generate shockwaves, which have found applications in nuclear fusion, proton imaging, cancer therapies and materials science. Collisionless electrostatic shocks are one type of shockwave widely studied for applications involving ion acceleration. Here we show a novel mechanism for collisionless electrostatic shocks to heat small amounts of solid density matter to temperatures of ∼keV in tens of femtoseconds. Unusually, electrons play no direct role in the heating and it is the ions that determine the heating rate. Ions are heated due to an interplay between the electric field of the shock, the local density increase during the passage of the shock and collisions between different species of ion. In simulations, these factors combine to produce rapid, localized heating of the lighter ion species. Although the heated volume is modest, this would be one of the fastest heating mechanisms discovered if demonstrated in the laboratory. PMID:26563440

  15. Contemporary NMR Studies of Protein Electrostatics.

    PubMed

    Hass, Mathias A S; Mulder, Frans A A

    2015-01-01

    Electrostatics play an important role in many aspects of protein chemistry. However, the accurate determination of side chain proton affinity in proteins by experiment and theory remains challenging. In recent years the field of nuclear magnetic resonance spectroscopy has advanced the way that protonation states are measured, allowing researchers to examine electrostatic interactions at an unprecedented level of detail and accuracy. Experiments are now in place that follow pH-dependent (13)C and (15)N chemical shifts as spatially close as possible to the sites of protonation, allowing all titratable amino acid side chains to be probed sequence specifically. The strong and telling response of carefully selected reporter nuclei allows individual titration events to be monitored. At the same time, improved frameworks allow researchers to model multiple coupled protonation equilibria and to identify the underlying pH-dependent contributions to the chemical shifts.

  16. Micromachined silicon electrostatic chuck

    DOEpatents

    Anderson, R.A.; Seager, C.H.

    1996-12-10

    An electrostatic chuck is faced with a patterned silicon plate, created by micromachining a silicon wafer, which is attached to a metallic base plate. Direct electrical contact between the chuck face (patterned silicon plate`s surface) and the silicon wafer it is intended to hold is prevented by a pattern of flat-topped silicon dioxide islands that protrude less than 5 micrometers from the otherwise flat surface of the chuck face. The islands may be formed in any shape. Islands may be about 10 micrometers in diameter or width and spaced about 100 micrometers apart. One or more concentric rings formed around the periphery of the area between the chuck face and wafer contain a low-pressure helium thermal-contact gas used to assist heat removal during plasma etching of a silicon wafer held by the chuck. The islands are tall enough and close enough together to prevent silicon-to-silicon electrical contact in the space between the islands, and the islands occupy only a small fraction of the total area of the chuck face, typically 0.5 to 5 percent. The pattern of the islands, together with at least one hole bored through the silicon veneer into the base plate, will provide sufficient gas-flow space to allow the distribution of the helium thermal-contact gas. 6 figs.

  17. Micromachined silicon electrostatic chuck

    DOEpatents

    Anderson, Robert A.; Seager, Carleton H.

    1996-01-01

    An electrostatic chuck is faced with a patterned silicon plate 11, created y micromachining a silicon wafer, which is attached to a metallic base plate 13. Direct electrical contact between the chuck face 15 (patterned silicon plate's surface) and the silicon wafer 17 it is intended to hold is prevented by a pattern of flat-topped silicon dioxide islands 19 that protrude less than 5 micrometers from the otherwise flat surface of the chuck face 15. The islands 19 may be formed in any shape. Islands may be about 10 micrometers in diameter or width and spaced about 100 micrometers apart. One or more concentric rings formed around the periphery of the area between the chuck face 15 and wafer 17 contain a low-pressure helium thermal-contact gas used to assist heat removal during plasma etching of a silicon wafer held by the chuck. The islands 19 are tall enough and close enough together to prevent silicon-to-silicon electrical contact in the space between the islands, and the islands occupy only a small fraction of the total area of the chuck face 15, typically 0.5 to 5 percent. The pattern of the islands 19, together with at least one hole 12 bored through the silicon veneer into the base plate, will provide sufficient gas-flow space to allow the distribution of the helium thermal-contact gas.

  18. A spherical electrostatic orrery

    NASA Astrophysics Data System (ADS)

    Smetana, Carole; Alexander, David; Robertson, Scott; Vilkaitis, Kim; Walch, Bob

    1996-11-01

    An electrostatic orrery for studying Keplerian orbits has been constructed in which one or more negatively charged hollow glass microparticles orbit a 9.5-mm-diam metal sphere at +8-kV potential in a vacuum. The device is similar to an earlier cylindrical orrery in which particles orbit a rod [Biewer et al., Am. J. Phys. 62(9), 821-827 (1994)]. Electrically biased cylinders covering the rod supporting the sphere give nearly spherical potential surfaces inside the trap. Additional electrodes at the boundary are used to reduce the perturbation of gravity and to prevent motion resulting in collisions with the supporting rod. Orbits last approximately 10 min or about 104 revolutions. The orbiters are illuminated with a slide projector and can be seen with the naked eye as well as videotaped. The trap has been used to observe orbital precession, interparticle collisions, and the effects of time-independent perturbations. This apparatus provides an opportunity for the study and demonstration of orbital motion in a laboratory.

  19. Cascaded proton acceleration by collisionless electrostatic shock

    SciTech Connect

    Xu, T. J.; Shen, B. F. E-mail: zhxm@siom.ac.cn; Zhang, X. M. E-mail: zhxm@siom.ac.cn; Yi, L. Q.; Wang, W. P.; Zhang, L. G.; Xu, J. C.; Zhao, X. Y.; Shi, Y.; Liu, C.; Pei, Z. K.

    2015-07-15

    A new scheme for proton acceleration by cascaded collisionless electrostatic shock (CES) is proposed. By irradiating a foil target with a moderate high-intensity laser beam, a stable CES field can be induced, which is employed as the accelerating field for the booster stage of proton acceleration. The mechanism is studied through simulations and theoretical analysis, showing that a 55 MeV seed proton beam can be further accelerated to 265 MeV while keeping a good energy spread. This scheme offers a feasible approach to produce proton beams with energy of hundreds of MeV by existing available high-intensity laser facilities.

  20. Nonadiabatic transitions in electrostatically trapped ammonia molecules

    SciTech Connect

    Kirste, Moritz; Schnell, Melanie; Meijer, Gerard; Sartakov, Boris G.

    2009-05-15

    Nonadiabatic transitions are known to be major loss channels for atoms in magnetic traps but have thus far not been experimentally reported upon for trapped molecules. We have observed and quantified losses due to nonadiabatic transitions for three isotopologues of ammonia in electrostatic traps by comparing the trapping times in traps with a zero and a nonzero electric field at the center. Nonadiabatic transitions are seen to dominate the overall loss rate even for the present samples that are at relatively high temperatures of 30 mK. It is anticipated that losses due to nonadiabatic transitions in electric fields are omnipresent in ongoing experiments on cold molecules.

  1. EVALUATION OF THE HIGH VOLUME COLLECTION SYSTEM (HVCS) FOR QUANTIFYING FUGITIVE ORGANIC VAPOR LEAKS

    EPA Science Inventory

    The report discusses a recently developed measurements technique that offers the potential for providing an easy-to-use and cost effective means to directly measure organic vapor leaks. The method, called High Volume Collection System (HVCS), uses a high volume sampling device an...

  2. EVALUATION OF THE HIGH VOLUME COLLECTION SYSTEM (HVCS) FOR QUANTIFYING FUGITIVE ORGANIC VAPOR LEAKS

    EPA Science Inventory

    The report discusses a recently developed measurements technique that offers the potential for providing an easy-to-use and cost effective means to directly measure organic vapor leaks. The method, called High Volume Collection System (HVCS), uses a high volume sampling device an...

  3. Explosion safety in industrial electrostatics

    NASA Astrophysics Data System (ADS)

    Szabó, S. V.; Kiss, I.; Berta, I.

    2011-01-01

    Complicated industrial systems are often endangered by electrostatic hazards, both from atmospheric (lightning phenomenon, primary and secondary lightning protection) and industrial (technological problems caused by static charging and fire and explosion hazards.) According to the classical approach protective methods have to be used in order to remove electrostatic charging and to avoid damages, however no attempt to compute the risk before and after applying the protective method is made, relying instead on well-educated and practiced expertise. The Budapest School of Electrostatics - in close cooperation with industrial partners - develops new suitable solutions for probability based decision support (Static Control Up-to-date Technology, SCOUT) using soft computing methods. This new approach can be used to assess and audit existing systems and - using the predictive power of the models - to design and plan activities in industrial electrostatics.

  4. Computational Methods for Biomolecular Electrostatics

    PubMed Central

    Dong, Feng; Olsen, Brett; Baker, Nathan A.

    2008-01-01

    An understanding of intermolecular interactions is essential for insight into how cells develop, operate, communicate and control their activities. Such interactions include several components: contributions from linear, angular, and torsional forces in covalent bonds, van der Waals forces, as well as electrostatics. Among the various components of molecular interactions, electrostatics are of special importance because of their long range and their influence on polar or charged molecules, including water, aqueous ions, and amino or nucleic acids, which are some of the primary components of living systems. Electrostatics, therefore, play important roles in determining the structure, motion and function of a wide range of biological molecules. This chapter presents a brief overview of electrostatic interactions in cellular systems with a particular focus on how computational tools can be used to investigate these types of interactions. PMID:17964951

  5. Anionic lipids and the maintenance of membrane electrostatics in eukaryotes

    PubMed Central

    Platre, Matthieu Pierre

    2017-01-01

    ABSTRACT A wide range of signaling processes occurs at the cell surface through the reversible association of proteins from the cytosol to the plasma membrane. Some low abundant lipids are enriched at the membrane of specific compartments and thereby contribute to the identity of cell organelles by acting as biochemical landmarks. Lipids also influence membrane biophysical properties, which emerge as an important feature in specifying cellular territories. Such parameters are crucial for signal transduction and include lipid packing, membrane curvature and electrostatics. In particular, membrane electrostatics specifies the identity of the plasma membrane inner leaflet. Membrane surface charges are carried by anionic phospholipids, however the exact nature of the lipid(s) that powers the plasma membrane electrostatic field varies among eukaryotes and has been hotly debated during the last decade. Herein, we discuss the role of anionic lipids in setting up plasma membrane electrostatics and we compare similarities and differences that were found in different eukaryotic cells. PMID:28102755

  6. The Contribution of Surface Potential to Diverse Problems in Electrostatics

    NASA Astrophysics Data System (ADS)

    Horenstein, M.

    2015-10-01

    Electrostatics spans many different subject areas. Some comprise “good electrostatics,” where charge is used for desirable purposes. Such areas include industrial manufacturing, electrophotography, surface modification, precipitators, aerosol control, and MEMS. Other areas comprise “bad electrostatics,” where charge is undesirable. Such areas include hazardous discharges, ESD, health effects, nuisance triboelectrification, particle contamination, and lightning. Conference proceedings such as this one inevitably include papers grouped around these topics. One common thread throughout is the surface potential developed when charge resides on an insulator surface. Often, the charged insulator will be in intimate contact with a ground plane. At other times, the charged insulator will be isolated. In either case, the resulting surface potential is important to such processes as propagating brush discharges, charge along a moving web, electrostatic biasing effects in MEMS, non-contacting voltmeters, field-effect transistor sensors, and the maximum possible charge on a woven fabric.

  7. Effect of particle distribution on electrostatic tomography system

    NASA Astrophysics Data System (ADS)

    Gao, Heming; Xu, Chuanlong; Fu, Feifei; Wang, Shimin

    2012-03-01

    Particle is charged due to frictional contact and collisions between particles and pipe wall. Electrostatic tomography technology (EST) is used to monitor the traveling particle charge. However the electric field distribution in the electrostatic sensor arrays is simultaneously affected by both the particle permittivity distribution and particle charge. In the paper, the effect of the different particle flow regimes on EST is investigated numerically and experimentally. Results indicated the particle distribution affected the induced charge on the electrostatic sensor array. But the effect relates to the relationship between the charge distribution and the particle distribution. Furthermore, a fusion of dual modality tomography system consisting of a capacitance sensor and electrostatic sensor arrays is used to investigate the relationship between the particle distribution and charge distribution in a gravity conveying rig. Results showed that the higher particle concentration has higher charge distribution in the gravity conveying rig. Additionally, the measurement of the mass flow rate by EST was investigated.

  8. Electrostatic Transport and Manipulation of Lunar Soil and Dust

    SciTech Connect

    Kawamoto, Hiroyuki

    2008-01-21

    Transport and manipulation technologies of lunar soil and dust are under development utilizing the electrostatic force. Transport of particles is realized by an electrostatic conveyer consisting of parallel electrodes. Four-phase traveling electrostatic wave was applied to the electrodes to transport particles upon the conveyer and it was demonstrated that particles were efficiently transported under conditions of low frequency, high voltage, and the application of rectangular wave. Not only linear but also curved and closed transport was demonstrated. Numerical investigation was carried out with a three-dimensional hard-sphere model of the Distinct Element Method to clarify the mechanism of the transport and to predict performances in the lunar environment. This technology is expected to be utilized not only for the transport of bulk soil but also for the cleaning of a solar panel and an optical lens. Another technology is an electrostatic manipulation system to manipulate single particle. A manipulator consisted of two parallel pin electrodes. When voltage was applied between the electrodes, electrophoresis force generated in non-uniform electrostatic field was applied to the particle near the tip of the electrode. The particle was captured by the application of the voltage and released from the manipulator by turning off the voltage. It was possible to manipulate not only insulative but also conductive particles. Three-dimensional electrostatic field calculation was conducted to calculate the electrophoresis force and the Coulomb force.

  9. Electrostatic prepregging of thermoplastic matrices

    NASA Technical Reports Server (NTRS)

    Muzzy, John D.; Varughese, Babu; Thammongkol, Vivan; Tincher, Wayne

    1989-01-01

    Thermoplastic towpregs of PEEK/AS-4, PEEK/S-2 glass and LaRC-TPI/AS-4, produced by electrostatic deposition of charged and fluidized polymer powders on spread continuous fiber tows, are described. Processing parameters for combining PEEK 150 powder with unsized 3k AS-4 carbon fiber are presented. The experimental results for PEEK 150/AS-4 reveal that electrostatic fluidized bed coating may be an economically attractive process for producing towpreg.

  10. Brownian dynamics simulation of electrostatically interacting proteins

    NASA Astrophysics Data System (ADS)

    Ermakova, E.; Krushelnitsky, A. G.; Fedotov, V. D.

    Brownian dynamics simulation software has been developed to study the dynamics of proteins as a whole in solution. The proteins were modelled as spheres with point dipoles embedded in the centre of sphere. A set of Brownian dynamics simulations at different values of the dipole moments, protein concentration and translational diffusion coefficient was performed to investigate the influence of interprotein electrostatic interactions on dynamic protein behaviour in solution. It was shown that these interactions led to the slowing down of protein rotation and a complex non-exponential shape of the rotational correlation function. Analysis of the correlation functions was performed within the frame of the model of electrostatic interprotein interactions advanced earlier on the basis of NMR and dielectric spectroscopy data. This model assumes that, due to electrostatic interactions, protein Brownian rotation becomes anisotropic. The lifetime of this anisotropy is controlled mainly by translational diffusion of proteins. Thus, the correlation function can be decomposed into two components corresponding to anisotropic Brownian rotation and an isotropic motion of an external electric field vector produced by the surrounding proteins.

  11. Shielding Electrostatic Fields in Polar Semiconductor Nanostructures

    NASA Astrophysics Data System (ADS)

    Hönig, G. M. O.; Westerkamp, S.; Hoffmann, A.; Callsen, G.

    2017-02-01

    Polar semiconductor materials enable a variety of classic and quantum-light sources, which are optimized continuously. However, one key problem—the inherent electric crystal polarization of such materials—remains unsolved and deteriorates the radiative exciton decay rate. We suggest a sequence of reverse interfaces to compensate these polarization effects, while the polar, natural crystal growth direction is maintained. Former research approaches, like growth on less-polar crystal planes or even the stabilization of unnatural phases, never reached industrial maturity. In contrast, our concept provides a way for the development of ultrafast devices based on established growth processes for polar materials, while the electric potential landscape becomes adjustable.

  12. Factors that influence minority use of high-volume hospitals for colorectal cancer care.

    PubMed

    Huang, Lyen C; Tran, Thuy B; Ma, Yifei; Ngo, Justine V; Rhoads, Kim F

    2015-05-01

    Previous studies suggest that minorities cluster in low-quality hospitals despite living close to better performing hospitals. This may contribute to persistent disparities in cancer outcomes. The purpose of this work was to examine how travel distance, insurance status, and neighborhood socioeconomic factors influenced minority underuse of high-volume hospitals for colorectal cancer. The study was a retrospective, cross-sectional, population-based study. All hospitals in California from 1996 to 2006 were included. Patients with colorectal cancer diagnosed and treated in California between 1996 and 2006 were identified using California Cancer Registry data. Multivariable logistic regression models predicting high-volume hospital use were adjusted for age, sex, race, stage, comorbidities, insurance status, and neighborhood socioeconomic factors. A total of 79,231 patients treated in 417 hospitals were included in the study. High-volume hospitals were independently associated with an 8% decrease in the hazard of death compared with other settings. A lower proportion of minorities used high-volume hospitals despite a higher proportion living nearby. Although insurance status and socioeconomic factors were independently associated with high-volume hospital use, only socioeconomic factors attenuated differences in high-volume hospital use of black and Hispanic patients compared with white patients. The use of cross-sectional data and racial and ethnic misclassifications were limitations in this study. Minority patients do not use high-volume hospitals despite improved outcomes and geographic access. Low socioeconomic status predicts low use of high-volume settings in select minority groups. Our results provide a roadmap for developing interventions to increase the use of and access to higher quality care and outcomes. Increasing minority use of high-volume hospitals may require community outreach programs and changes in physician referral practices.

  13. Electrostatic forces in wind-pollination—Part 1: Measurement of the electrostatic charge on pollen

    NASA Astrophysics Data System (ADS)

    Bowker, George E.; Crenshaw, Hugh C.

    Under fair weather conditions, a weak electric field exists between negative charge induced on the surface of plants and positive charge in the air. This field is magnified around points (e.g. stigmas) and can reach values up to 3×10 6 V m -1. If wind-dispersed pollen grains are electrically charged, the electrostatic force (which is the product of the pollen's charge and the electric field at the pollen's location) could influence pollen capture. In this article, we report measurements of the electrostatic charge carried by wind-dispersed pollen grains. Pollen charge was measured using an adaptation of the Millikan oil-drop experiment for seven anemophilous plants: Acer rubrum, Cedrus atlantica, Cedrus deodara, Juniperus virginiana, Pinus taeda, Plantago lanceolata and Ulmus alata. All species had charged pollen, some were positive others negative. The distributions (number of pollen grains as a function of charge) were bipolar and roughly centered about zero although some distributions were skewed towards positive charges. Most pollen carried small amounts of charge, 0.8 fC in magnitude, on average. A few carried charges up to 40 fC. For Juniperus, pollen charges were also measured in nature and these results concurred with those found in the laboratory. For nearly all charged pollen grains, the likelihood that electrostatics influence pollen capture is evident.

  14. RNA topology remolds electrostatic stabilization of viruses

    NASA Astrophysics Data System (ADS)

    Erdemci-Tandogan, Gonca; Wagner, Jef; van der Schoot, Paul; Podgornik, Rudolf; Zandi, Roya

    2014-03-01

    Simple RNA viruses efficiently encapsulate their genome into a nano-sized protein shell: the capsid. Spontaneous coassembly of the genome and the capsid proteins is driven predominantly by electrostatic interactions between the negatively charged RNA and the positively charged inner capsid wall. Using field theoretic formulation we show that the inherently branched RNA secondary structure allows viruses to maximize the amount of encapsulated genome and make assembly more efficient, allowing viral RNAs to out-compete cellular RNAs during replication in infected host cells.

  15. RNA topology remolds electrostatic stabilization of viruses.

    PubMed

    Erdemci-Tandogan, Gonca; Wagner, Jef; van der Schoot, Paul; Podgornik, Rudolf; Zandi, Roya

    2014-03-01

    Simple RNA viruses efficiently encapsulate their genome into a nano-sized protein shell: the capsid. Spontaneous coassembly of the genome and the capsid proteins is driven predominantly by electrostatic interactions between the negatively charged RNA and the positively charged inner capsid wall. Using field theoretic formulation we show that the inherently branched RNA secondary structure allows viruses to maximize the amount of encapsulated genome and make assembly more efficient, allowing viral RNAs to out-compete cellular RNAs during replication in infected host cells.

  16. Multiple magnetic microrobot control using electrostatic anchoring

    NASA Astrophysics Data System (ADS)

    Pawashe, Chytra; Floyd, Steven; Sitti, Metin

    2009-04-01

    Addressing power and control to individual untethered microrobots is a challenge for small-scale robotics. We present a 250×130×100 μm3 magnetic robot wirelessly driven by pulsed external magnetic fields. An induced stick-slip motion results in translation speeds over 8 mm/s. Control of multiple robots is achieved by an array of addressable electrostatic anchoring pads on the surface, which selectively fixes microrobots, preventing translation. We demonstrate control of two microrobots in both uncoupled individual motion and coupled symmetric motion. An estimated anchoring force of 23.0 μN is necessary to effectively fix each microrobot.

  17. Analyzing electrostatic induced damage risk to reticles with an in situ e-reticle system

    NASA Astrophysics Data System (ADS)

    Tu, Richard; Sebald, Thomas

    2009-12-01

    E-Reticle system is an electrostatic field test device, which has the form factor of a conventional six inch quartz production reticle. The E-Reticle was used to assess the ESD damage risks in a mask cleaning tool. Test results indicate that a reticle may see higher than ITRS recommended electrostatic potential specifications when mechanical operations and cold DIW rinse start and in progress, hence seeing increased probability of electrostatic induced damages.

  18. Scaling relations for a neutron yield in a plasma with inertial electrostatic confinement

    NASA Astrophysics Data System (ADS)

    Gus'kov, S. Yu.; Kurilenkov, Yu. K.

    2017-05-01

    We discuss the possibilities of producing a high-power source of thermonuclear neutrons under inertial electrostatic confinement of a plasma in the process of periodic oscillations of hydrogen isotope nuclei in the field of a virtual cathode of an electrostatic trap. The investigations are performed using analytical scaling relations, which explicitly give the dependence of a neutron yield on the electrostatic trap parameters under various operating conditions. Presented at the ECLIM 2016 conference (Moscow, 18 - 23 September 2016).

  19. Nanoimprint system development and status for high volume semiconductor manufacturing

    NASA Astrophysics Data System (ADS)

    Hiura, Hiromi; Takabayashi, Yukio; Takashima, Tsuneo; Emoto, Keiji; Choi, Jin; Schumaker, Phil

    2016-10-01

    Imprint lithography has been shown to be an effective technique for replication of nano-scale features. Jet and Flash Imprint Lithography* (J-FIL*) involves the field-by-field deposition and exposure of a low viscosity resist deposited by jetting technology onto the substrate. The patterned mask is lowered into the fluid which then quickly flows into the relief patterns in the mask by capillary action. Following this filling step, the resist is crosslinked under UV radiation, and then the mask is removed, leaving a patterned resist on the substrate. There are many criteria that determine whether a particular technology is ready for wafer manufacturing. For imprint lithography, recent attention has been given to the areas of overlay, throughput, defectivity, and mask replication. This paper reviews progress in these critical areas. Recent demonstrations have proven that mix and match overlay of less than 5nm can achieved. Further reductions require a higher order correction system. Modeling and experimental data are presented which provide a path towards reducing the overlay errors to less than 3nm. Throughput is mainly impacted by the fill time of the relief images on the mask. Improvement in resist materials provides a solution that allows 15 wafers per hour per station, or a tool throughput of 60 wafers per hour. Defectivity and mask life play a significant role relative to meeting the cost of ownership (CoO) requirements in the production of semiconductor devices. Hard particles on a wafer or mask create the possibility of inducing a permanent defect on the mask that can impact device yield and mask life. By using material methods to reduce particle shedding and by introducing an air curtain system, the lifetime of both the master mask and the replica mask can be extended. In this work, we report results that demonstrate a path towards achieving mask lifetimes of better than 1000 wafers. Finally, on the mask side, a new replication tool, the FPA-1100NR2 is

  20. Dimer packings with gaps and electrostatics

    PubMed Central

    Ciucu, Mihai

    2008-01-01

    Fisher and Stephenson conjectured in 1963 that the correlation function (defined by dimer packings) of two unit holes on the square lattice is rotationally invariant in the limit of large separation between the holes. We consider the same problem on the hexagonal lattice, extend it to an arbitrary finite collection of holes, and present an explicit conjectural answer. In recent work we managed to prove this conjecture in two fairly general cases. The quantity giving the answer can be regarded as the exponential of the negative of the two-dimensional electrostatic energy of a system of charges naturally associated with the holes. We further develop this analogy to electrostatics by presenting two different natural ways to define a field in our setup, and showing that both lead to the electric field, in the limit of large separations between the holes. For one of the fields, this is also stated as a limit shape theorem for random surfaces, with the continuum limit being a sum of helicoids. We conclude by explaining the relationship of our results to previous results in the physics literature on spin correlations in the Ising model.

  1. High-volume hydrodissection: increasing the safety and efficiency of perforator dissection.

    PubMed

    Singhal, Dhruv; Fanzio, Paolo M; Lee, Ethan T; Chang, Chee J; Lee, Bernard T; Cheng, Ming-Huei

    2014-08-01

    Although perforator flaps have advanced the field of reconstructive microsurgery, these flaps increase operative time and difficulty of dissection. A prospective experimental animal study was performed to study the use of high-volume hydrodissection to simultaneously decrease the operative time while increasing the safety of perforator dissection. Sixteen Sprague-Dawley rats underwent bilateral "deep inferior epigastric perforator" flap dissections with hydrodissection used on the study side and a traditional dissection performed on the control side. Primary outcome measurements included dissection time and dissection difficulty score (1-5 in order of increasing difficulty). The mean (SD) dissection time for the hydrodissected perforators was 9.29 (2.50) minutes versus 13.22 (2.44) minutes for the control perforators (P < 0.001). The mean (SD) dissection difficulty score was 4.44 (0.73) for the dissection of the control side compared with 1.69 (0.87) for the hydrodissected side (P < 0.001). The mechanical benefits of hydrodissection of perforators were evident in reduction of perforator dissection time and difficulty.

  2. Synthesis of electrostatic multielectrode deflectors

    SciTech Connect

    Cho, H.; Szilagyi, M.

    1995-09-01

    Synthesis of electrostatic deflectors with given source parameters, first-order properties, and minimum aberrations can be realized by using the cubic spline method or the {ital a} {ital priori} given multielectrode approach. Synthesis of electrostatic deflectors was successfully achieved previously by using the cubic spline method. In this paper we present synthesis of electrostatic deflectors based on the {ital a} {ital priori} given multielectrode approach for the purpose of obtaining the minimum beam spot size through a sequential optimization technique. Our calculations show that the third-order geometrical deflection aberrations can be reduced by about two to three orders of magnitude using a multielectrode deflector with three units or five units, each having short cylindrical segments with geometrically octupole symmetry. {copyright} {ital 1995} {ital American} {ital Vacuum} {ital Society}

  3. PREFACE: 7th International Conference on Applied Electrostatics (ICAES-2012)

    NASA Astrophysics Data System (ADS)

    Li, Jie

    2013-03-01

    Faculty of Engineering, McMaster University, Canada), Haitian Scholar of Dalian University of Technology (China), who passed away on 27 February 2011. Professor Chang was active in research fields including the applications of electrostatics, electromagnetic hydrodynamics, plasma environmental pollution control technologies, etc and he contributed much to the development of these fields. Professor Chang was the visiting professor at some Key Universities in China and was the friend of Chinese scholars engaged in electrostatics. Professor Chang was also active in joining and supporting the previous ICAES. We will cherish the memory of Professor Jen-Shih Chang forever. Professor Jie Li Proceedings Editor Dalian, September 2012 Conference photograph

  4. Electrostatic Surface Characterization by Scanning Probe Microscopy.

    NASA Astrophysics Data System (ADS)

    Leng, Yaojian

    1995-01-01

    The electrostatic properties of surfaces are important in biological, polymer and semiconductor physics. Several newly developed scanning probe microscopies can provide nanometer scale characterization of these surfaces. In the course of this work, an Electrostatic Force Microscope (EFM) and a Kelvin Probe Force Microscope (KPFM) have been built using interferometric force detection. An EFM is a modified noncontact mode Atomic Force Microscope, capable of simultaneously measuring surface topography, surface charge or surface potential, and capacitance. A KPFM is similar to the classical Kelvin method in measuring surface potential, only in this case, forces are detected instead of currents. A 10^{-4} A/surdHz displacement detection sensitivity has been achieved. A 200 A spatial resolution and a sub-mV electrostatic potential sensitivity have been demonstrated. The capability of the EFM to map charge and dielectric variations on biological and polymeric surfaces has been demonstrated. Studies have been made on red blood cells, modified Teflon FEP films, and contact lens materials. A quantitative method to measure surface charge density on a nanometer scale has been established. The redistribution of mobile surface ions has been visualized for the first time by the EFM on a submicron scale. It has been shown that the drift in the saturation current observed on the open gate field effect transistor is due to the migration of mobile surface ions under lateral fields. Atomic ordering in GaInP, controlled either by growth temperature or by substrate misorientation, has been studied by the KPFM both in cross section and on the growth plane. It is shown that KPFM is capable of distinguishing ordered GaInP from disordered GaInP. The contrast is observed to depend on the applied ac amplitude used in the measurement. The experiments indicate that ordering in GaInP modifies the density and/or lifetime of the surface states.

  5. Electrostatic Unbalances of Transmission Lines.

    DTIC Science & Technology

    1985-08-01

    RD-A±68 742 ELECTROSTATIC UMBALANCES OF TEMNISSION LINES(U) AIR 1V2 FORCE INST OF TECH WRIGHNT-PATTERSON AFD OH J NOUIKOWSKI AUG 85 AFIT/CI/ NR -BS...CONTROLLING OFFICE NAME AND ADORESS 12. REPORT DATE AFIT/ NR 1985 WPAFB OH 45433 - 6583 1i. NUMBER OF PAGES ___102 14. MONITORING AGENCY NAME & ADDRESS...return it to: AF IT/ NR Wright-Patterson AFB OH 45433 RESEARCH TITLE: Electrostatic Unbalances oJCTransmission Lines *AUTHOR: Jioseph Nowikowski

  6. Electrostatically actuatable light modulating device

    DOEpatents

    Koehler, Dale R.

    1991-01-01

    The electrostatically actuatable light modulator utilizes an opaque substrate plate patterned with an array of aperture cells, the cells comprised of physically positionable dielectric shutters and electrostatic actuators. With incorporation of a light source and a viewing screen, a projection display system is effected. Inclusion of a color filter array aligned with the aperture cells accomplishes a color display. The system is realized in terms of a silicon based manufacturing technology allowing fabrication of a high resolution capability in a physically small device which with the utilization of included magnification optics allows both large and small projection displays.

  7. Fabrication of nanoscale electrostatic lenses

    NASA Astrophysics Data System (ADS)

    Sinno, I.; Sanz-Velasco, A.; Kang, S.; Jansen, H.; Olsson, E.; Enoksson, P.; Svensson, K.

    2010-09-01

    The fabrication of cylindrical multi-element electrostatic lenses at the nanoscale presents a challenge; they are high-aspect-ratio structures that should be rotationally symmetric, well aligned and freestanding, with smooth edges and flat, clean surfaces. In this paper, we present the fabrication results of a non-conventional process, which uses a combination of focused gallium ion-beam milling and hydrofluoric acid vapor etching. This process makes it possible to fabricate nanoscale electrostatic lenses down to 140 nm in aperture diameter and 4.2 µm in column length, with a superior control of the geometry as compared to conventional lithography-based techniques.

  8. Electrostatics at the molecular level

    NASA Astrophysics Data System (ADS)

    Zürcher, Ulrich

    2017-01-01

    In molecular systems, positive and negative charges are separated, making them ideal systems to examine electrostatic interactions. The attractive force between positive and negative charges is balanced by repulsive ‘forces’ that are quantum-mechanical in origin. We introduce an ‘effective’ potential energy that captures the repulsion; it allows us to obtain fairly accurate estimates of the bonding properties of molecular systems. We use units (e.g., kcal mol-1 for energy) that emphasize the relevance of electrostatics to macroscopic behavior.

  9. Electrostatic Modeling of Vacuum Insulator Triple Junctions

    SciTech Connect

    Tully, L K; Goerz, D A; Houck, T L; Javedani, J B

    2006-10-25

    Triple junctions are often initiation points for insulator flashover in pulsed power devices. The two-dimensional finite-element TriComp [1] modeling software suite was utilized for its electrostatic field modeling package to investigate electric field behavior in the anode and cathode triple junctions of a high voltage vacuum-insulator interface. TriComp enables simple extraction of values from a macroscopic solution for use as boundary conditions in a subset solution. Electric fields computed with this zoom capability correlate with theoretical analysis of the anode and cathode triple junctions within submicron distances for nominal electrode spacing of 1.0 cm. This paper will discuss the iterative zoom process with TriComp finite-element software and the corresponding theoretical verification of the results.

  10. Circuit Compatible Model for Electrostatic Doped Schottky Barrier CNTFET

    NASA Astrophysics Data System (ADS)

    Singh, Amandeep; Khosla, Mamta; Raj, Balwinder

    2016-10-01

    This paper proposes a circuit compatible model for electrostatic doped Schottky barrier carbon nanotube field effect transistor (ED-SBCNTFET). The proposed model is an extension of the Schottky barrier carbon nanotube field effect transistor (SBCNTFET) to ED-SBCNTFET by adding polarity gates, which are used to create electrostatic doping. In ED-SBCNTFET, electrostatic doping is responsible for a fermi level shift of source and drain regions. A mathematical relation has been developed between fermi level shift and polarity gate bias. Both current-voltage ( I- V) and capacitance-voltage ( C- V) characteristics have been efficiently modeled. The results are compared with the reported semi-classical model and simulations from NanoTCAD ViDES for validation. The proposed model is much faster than numerical models as it denies self consistent equations. Finally, circuit application is demonstrated by simulating inverter using the proposed model in HSPICE.

  11. Electrostatic Limit of Detection of Nanowire-Based Sensors.

    PubMed

    Henning, Alex; Molotskii, Michel; Swaminathan, Nandhini; Vaknin, Yonathan; Godkin, Andrey; Shalev, Gil; Rosenwaks, Yossi

    2015-10-07

    Scanning gate microscopy is used to determine the electrostatic limit of detection (LOD) of a nanowire (NW) based chemical sensor with a precision of sub-elementary charge. The presented method is validated with an electrostatically formed NW whose active area and shape are tunable by biasing a multiple gate field-effect transistor (FET). By using the tip of an atomic force microscope (AFM) as a local top gate, the field effect of adsorbed molecules is emulated. The tip induced charge is quantified with an analytical electrostatic model and it is shown that the NW sensor is sensitive to about an elementary charge and that the measurements with the AFM tip are in agreement with sensing of ethanol vapor. This method is applicable to any FET-based chemical and biological sensor, provides a means to predict the absolute sensor performance limit, and suggests a standardized way to compare LODs and sensitivities of various sensors.

  12. Guide to Coupled Electrostatic-Structural Analyses with Arpeggio

    SciTech Connect

    Porter, Vicki L.

    2006-09-01

    Many applications in micromechanical systems (MEMS) involve electrostatically actuated parts. Arpeggio is a code for facilitating loose coupling between computational mechanics modules in a parallel computing environment. This document describes how to use Arpeggio for coupled elecromechanical analyses using examples commonly encountered in MEMS applications, namely the response of structures to loads imposed by electrostatic fields. For this type of analysis, Arpeggio is used to couple Adagio, a three dimensional finite element code for nonlinear, quasi static or implicit dynamic analysis of three-dimensional structures, with BEM, a boundary integral method code for the analysis of electrostatic fields. This guide describes the methodology used for the loose coupling and the commands the user needs in an input file to perform such an analysis. All commands related to coupled analyses are described and examples are provided.

  13. Electrostatic lens to focus an ion beam to uniform density

    DOEpatents

    Johnson, Cleland H.

    1977-01-11

    A focusing lens for an ion beam having a gaussian or similar density profile is provided. The lens is constructed to provide an inner zero electrostatic field, and an outer electrostatic field such that ions entering this outer field are deflected by an amount that is a function of their distance from the edge of the inner field. The result is a beam that focuses to a uniform density in a manner analogous to that of an optical ring lens. In one embodiment, a conically-shaped network of fine wires is enclosed within a cylindrical anode. The wire net together with the anode produces a voltage field that re-directs the outer particles of the beam while the axial particles pass undeflected through a zero field inside the wire net. The result is a focused beam having a uniform intensity over a given target area and at a given distance from the lens.

  14. Miniature Free-Space Electrostatic Ion Thrusters

    NASA Technical Reports Server (NTRS)

    Hartley, Frank T.; Stephens, James B.

    2006-01-01

    A miniature electrostatic ion thruster is proposed for maneuvering small spacecraft. In a thruster based on this concept, one or more propellant gases would be introduced into an ionizer based on the same principles as those of the device described in an earlier article, "Miniature Bipolar Electrostatic Ion Thruster". On the front side, positive ions leaving an ionizer element would be accelerated to high momentum by an electric field between the ionizer and an accelerator grid around the periphery of the concave laminate structure. On the front side, electrons leaving an ionizer element would be ejected into free space by a smaller accelerating field. The equality of the ion and electron currents would eliminate the need for an additional electron- or ion-emitting device to keep the spacecraft charge-neutral. In a thruster design consisting of multiple membrane ionizers in a thin laminate structure with a peripheral accelerator grid, the direction of thrust could then be controlled (without need for moving parts in the thruster) by regulating the supply of gas to specific ionizer.

  15. Electrostatic Precipitator (ESP) TRAINING MANUAL

    EPA Science Inventory

    The manual assists engineers in using a computer program, the ESPVI 4.0W, that models all elements of an electrostatic precipitator (ESP). The program is a product of the Electric Power Research Institute and runs in the Windows environment. Once an ESP is accurately modeled, the...

  16. Defining protein electrostatic recognition processes

    NASA Astrophysics Data System (ADS)

    Getzoff, Elizabeth D.; Roberts, Victoria A.

    The objective is to elucidate the nature of electrostatic forces controlling protein recognition processes by using a tightly coupled computational and interactive computer graphics approach. The TURNIP program was developed to determine the most favorable precollision orientations for two molecules by systematic search of all orientations and evaluation of the resulting electrostatic interactions. TURNIP was applied to the transient interaction between two electron transfer metalloproteins, plastocyanin and cytochrome c. The results suggest that the productive electron-transfer complex involves interaction of the positive region of cytochrome c with the negative patch of plastocyanin, consistent with experimental data. Application of TURNIP to the formation of the stable complex between the HyHEL-5 antibody and its protein antigen lysozyme showed that long-distance electrostatic forces guide lysozyme toward the HyHEL-5 binding site, but do not fine tune its orientation. Determination of docked antigen/antibody complexes requires including steric as well as electrostatic interactions, as was done for the U10 mutant of the anti-phosphorylcholine antibody S107. The graphics program Flex, a convenient desktop workstation program for visualizing molecular dynamics and normal mode motions, was enhanced. Flex now has a user interface and was rewritten to use standard graphics libraries, so as to run on most desktop workstations.

  17. Electrostatic Precipitator (ESP) TRAINING MANUAL

    EPA Science Inventory

    The manual assists engineers in using a computer program, the ESPVI 4.0W, that models all elements of an electrostatic precipitator (ESP). The program is a product of the Electric Power Research Institute and runs in the Windows environment. Once an ESP is accurately modeled, the...

  18. Aerial electrostatic-charged spray for deposition and efficacy against sweetpotato whitefly (Bemisia tabaci) on cotton

    USDA-ARS?s Scientific Manuscript database

    Efficacy of aerial electrostatic-charged sprays was evaluated for spray deposit characteristics and season-long control of sweet potato whitefly (SWF), Bemisia tabaci biotype B (a.k.a. B. argentifolii), in an irrigated 24-ha cotton field. Treatments included electrostatic-charged sprays at full and ...

  19. A Simple Apparatus for Electrostatic Force Measurement.

    ERIC Educational Resources Information Center

    Hale, D. P.

    1981-01-01

    Describes the construction of an apparatus that demonstrates that electrostatic forces can be large and also gives some idea of dependence of electrostatic forces between charged parallel discs on potential differences and separation. (CS)

  20. SPARCLE: Electrostatic Tool for Lunar Dust Control

    SciTech Connect

    Clark, P. E.; Curtis, S. A.; Minetto, F.; Cheung, C. Y.; Keller, J. F.; Moore, M.; Calle, C. I.

    2009-03-16

    Successful exploration of most planetary surfaces, with their impact-generated dusty regoliths, will depend on the capabilities to keep surfaces free of the dust which could compromise performance and to collect dust for characterization. Solving the dust problem is essential before we return to the Moon. During the Apollo missions, the discovery was made that regolith fines, or dust, behaved like abrasive velcro, coating surfaces, clogging mechanisms, and making movement progressively more difficult as it was mechanically stirred up during surface operations, and abrading surfaces, including spacesuits, when attempts were made to remove it manually. In addition, some of the astronauts experienced breathing difficulties when exposed to dust that got into the crew compartment. The successful strategy will deal with dust dynamics resulting from interaction between mechanical and electrostatic forces. Here we will describe the surface properties of dust particles, the basis for their behavior, and an electrostatically-based approach and methodology for addressing this issue confirmed by our preliminary results. Our device concept utilizes a focused electron beam to control the electrostatic potential of the surface. A plate of the opposite potential is then used to induce dust migration in the presence of an electrical field. Our goal is a compact device of <5 kg mass and using <5 watts of power to be operational in <5 years with heritage from ionic sweepers for active spacecraft potential control (e.g., on POLAR). Rovers could be fitted with devices that could harness the removal of dust for sampling as part of the extended exploration process on Mercury, Mars, asteroids or outer solar system satellites, as well as the Moon.

  1. [Research on sterilization of pathogens by high electrostatic voltage method].

    PubMed

    Wang, X; Wu, Y; Ni, X; Xia, B; Xu, J; Du, Q

    1992-10-01

    An experimental research has been carried out on the sterilization of four kinds of pathogens by high electrostatic method along with an inquiry into the influence of voltage waveform and the treated time on sterilization. It is concluded that pathogens can be killed efficiently by corona discharge field.

  2. ADVANCED ELECTROSTATIC STIMULATION OF FABRIC FILTRATION: PERFORMANCE AND ECONOMICS

    EPA Science Inventory

    The paper discusses the performance and economics of advanced electrostatic stimulation of fabric filtration (AESFF), in which a high-voltage electrode is placed coaxially inside a filter bag to establish an electric field between the electrode and the bag surface. The electric f...

  3. Electrostatic quadrupole focused particle accelerating assembly with laminar flow beam

    DOEpatents

    Maschke, A.W.

    1984-04-16

    A charged particle accelerating assembly provided with a predetermined ratio of parametric structural characteristics and with related operating voltages applied to each of its linearly spaced focusing and accelerating quadrupoles, thereby to maintain a particle beam traversing the electrostatic fields of the quadrupoles in the assembly in an essentially laminar flow through the assembly.

  4. Optimization and experimental validation of electrostatic adhesive geometry

    NASA Astrophysics Data System (ADS)

    Ruffatto, D.; Shah, J.; Spenko, M.

    This paper introduces a method to optimize the electrode geometry of electrostatic adhesives for robotic gripping, attachment, and manipulation applications. Electrostatic adhesion is achieved by applying a high voltage potential, on the order of kV, to a set of electrodes, which generates an electric field. The electric field polarizes the substrate material and creates an adhesion force. Previous attempts at creating electro-static adhesives have shown them to be effective, but researchers have made no effort to optimize the electrode configuration and geometry. We have shown that by optimizing the geometry of the electrode configuration, the electric field strength, and therefore the adhesion force, is enhanced. To accomplish this, Comsol Multiphysics was utilized to evaluate the average electric field generated by a given electrode geometry. Several electrode patterns were evaluated, including parallel conductors, concentric circles, Hilbert curves (a fractal geometry) and spirals. The arrangement of the electrodes in concentric circles with varying electrode widths proved to be the most effective. The most effective sizing was to use the smallest gap spacing allowable coupled with a variable electrode width. These results were experimentally validated on several different surfaces including drywall, wood, tile, glass, and steel. A new manufacturing process allowing for the fabrication of thin, conformal electro-static adhesive pads was utilized. By combining the optimized electrode geometry with the new fabrication process we are able to demonstrate a marked improvement of up to 500% in shear pressure when compared to previously published values.

  5. Electrostatic quadrupole focused particle accelerating assembly with laminar flow beam

    DOEpatents

    Maschke, Alfred W.

    1985-01-01

    A charged particle accelerating assembly provided with a predetermined ratio of parametric structural characteristics and with related operating voltages applied to each of its linearly spaced focusing and accelerating quadrupoles, thereby to maintain a particle beam traversing the electrostatic fields of the quadrupoles in the assembly in an essentially laminar flow throughout the assembly.

  6. ADVANCED ELECTROSTATIC STIMULATION OF FABRIC FILTRATION: PERFORMANCE AND ECONOMICS

    EPA Science Inventory

    The paper discusses the performance and economics of advanced electrostatic stimulation of fabric filtration (AESFF), in which a high-voltage electrode is placed coaxially inside a filter bag to establish an electric field between the electrode and the bag surface. The electric f...

  7. Electrostatic dispersion lenses and ion beam dispersion methods

    DOEpatents

    Dahl, David A [Idaho Falls, ID; Appelhans, Anthony D [Idaho Falls, ID

    2010-12-28

    An EDL includes a case surface and at least one electrode surface. The EDL is configured to receive through the EDL a plurality of ion beams, to generate an electrostatic field between the one electrode surface and either the case surface or another electrode surface, and to increase the separation between the beams using the field. Other than an optional mid-plane intended to contain trajectories of the beams, the electrode surface or surfaces do not exhibit a plane of symmetry through which any beam received through the EDL must pass. In addition or in the alternative, the one electrode surface and either the case surface or the other electrode surface have geometries configured to shape the field to exhibit a less abrupt entrance and/or exit field transition in comparison to another electrostatic field shaped by two nested, one-quarter section, right cylindrical electrode surfaces with a constant gap width.

  8. 3D simulations of an electrostatic quadrupole injector

    SciTech Connect

    Grote, D.P. |; Friedman, A.; Yu, S.

    1993-02-01

    Analysis of the dynamics of a space charge dominated beam in a lattice of electrostatic focusing structures requires a full three-dimensional conic that includes self-consistent space charge fields and the fields from the complex conductor shapes. The existing WARP3d code, a particle simulation code which has been developed for heavy-ion fusion (HIF) applications contains machinery for handling particles in three-dimensional fields. A successive overrelaxation field solver with subgrid-scale placement of boundaries for rounded surface and four-fold symmetry has been added to the code. The electrostatic quadrupole (ESQ) injector for the ILSE accelerator facility being planned at Lawrence Berkeley Laboratory is shown as an application. The issue of concern is possible emittance degradation because the focusing voltages are a significant fraction of the particles` energy and because there are significant nonlinear fields arising from the shapes of the quadrupole structures.

  9. Electrostatic effects in macromolecules: fundamental concepts and practical modeling.

    PubMed

    Warshel, A; Papazyan, A

    1998-04-01

    The past few years have seen an exponential growth in the calculations of electrostatic energies of macromolecules and an increased recognition of the crucial role of electrostatic effects. This review considers the current state of the field. Focus is placed on calculations of pKas, redox potentials and binding energies in macromolecules and clarification of the fact that the value of the dielectric 'constant' of a protein depends on its definition and that small dielectric constants should not be used in describing charge-charge interactions by current continuum models.

  10. Dust particles precipitation in AC/DC electrostatic precipitator

    NASA Astrophysics Data System (ADS)

    Jaworek, A.; Marchewicz, A.; Krupa, A.; Sobczyk, A. T.; Czech, T.; Antes, T.; Śliwiński, Ł.; Kurz, M.; Szudyga, M.; Rożnowski, W.

    2015-10-01

    Submicron and nanoparticles removal from flue or exhaust gases remain still a challenge for engineers. The most effective device used for gas cleaning in power plants or industry is electrostatic precipitator, but its collection efficiency steeply decreases for particles smaller than 1 micron. In this paper, fractional collection efficiency of two-stage electrostatic precipitator comprising of alternating electric field charger and DC supplied parallel-plate collection stage has been investigated. The total number collection efficiency for PM2.5 particles was higher than 95% and mass collection efficiency >99%. Fractional collection efficiency for particles between 300 nm and 1 μm was >95%.

  11. High-volume fly ash utilization projects in the United States and Canada. Final report

    SciTech Connect

    Patelunas, G.M.

    1986-02-01

    The purpose of this report is to document existing high-volume applications of fly ash. Examples of high-volume projects are: backfills, embankments, fills, landfill cover, pavement base course, soil amendment, subgrade stabilization, grouts and hydraulic fills. Information was solicited from electric utilities, state highway agencies, ash marketers, engineering firms and other organizations in the United States and Canada. Over 270 separate projects that used fly ash in high-volume applications were identified. Class F fly ash was used in 172 projects, and Class C fly ash was used in 108 projects. The most frequent high-volume use of Class F fly ash was for fills, embankments and pavement base courses. These projects are primarily located in the north central and mid-Atlantic states. The most frequent use of Class C fly ash was for subgrade stabilization. Most of these projects are located in the midwestern and southwestern United States. The existence of many different applications of fly ash documented during this project demonstrates that fly ash is a practical high-volume construction material.

  12. Lightning-induced extensive charge sheets provide long range electrostatic thunderstorm detection.

    PubMed

    Bennett, A J; Harrison, R G

    2013-07-26

    By combining electrostatic measurements of lightning-induced electrostatic field changes with radio frequency lightning location, some field changes from exceptionally distant lightning events are apparent which are inconsistent with the usual inverse cube of distance. Furthermore, by using two measurement sites, a transition zone can be identified beyond which the electric field response reverses polarity. For these severe lightning events, we infer a horizontally extensive charge sheet above a thunderstorm, consistent with a mesospheric halo of several hundred kilometers' extent.

  13. Quantitative nanoscale electrostatics of viruses

    NASA Astrophysics Data System (ADS)

    Hernando-Pérez, M.; Cartagena-Rivera, A. X.; Lošdorfer Božič, A.; Carrillo, P. J. P.; San Martín, C.; Mateu, M. G.; Raman, A.; Podgornik, R.; de Pablo, P. J.

    2015-10-01

    Electrostatics is one of the fundamental driving forces of the interaction between biomolecules in solution. In particular, the recognition events between viruses and host cells are dominated by both specific and non-specific interactions and the electric charge of viral particles determines the electrostatic force component of the latter. Here we probe the charge of individual viruses in liquid milieu by measuring the electrostatic force between a viral particle and the Atomic Force Microscope tip. The force spectroscopy data of co-adsorbed φ29 bacteriophage proheads and mature virions, adenovirus and minute virus of mice capsids is utilized for obtaining the corresponding density of charge for each virus. The systematic differences of the density of charge between the viral particles are consistent with the theoretical predictions obtained from X-ray structural data. Our results show that the density of charge is a distinguishing characteristic of each virus, depending crucially on the nature of the viral capsid and the presence/absence of the genetic material.Electrostatics is one of the fundamental driving forces of the interaction between biomolecules in solution. In particular, the recognition events between viruses and host cells are dominated by both specific and non-specific interactions and the electric charge of viral particles determines the electrostatic force component of the latter. Here we probe the charge of individual viruses in liquid milieu by measuring the electrostatic force between a viral particle and the Atomic Force Microscope tip. The force spectroscopy data of co-adsorbed φ29 bacteriophage proheads and mature virions, adenovirus and minute virus of mice capsids is utilized for obtaining the corresponding density of charge for each virus. The systematic differences of the density of charge between the viral particles are consistent with the theoretical predictions obtained from X-ray structural data. Our results show that the density of

  14. Theory of electrostatics and electrokinetics of soft particles.

    PubMed

    Ohshima, Hiroyuki

    2009-12-01

    We investigate theoretically the electrostatics and electrokinetics of a soft particle, i.e. a hard particle covered with an ion-penetrable surface layer of polyelectrolytes. The electric properties of soft particles in an electrolyte solution, which differ from those of hard particles, are essentially determined by the Donnan potential in the surface layer. In particular, the Donnan potential plays an essential role in the electrostatics and electrokinetics of soft particles. Furthermore, the concept of zeta potential, which is important in the electrokinetics of hard particles, loses its physical meaning in the electrokinetics of soft particles. In this review, we discuss the potential distribution around a soft particle, the electrostatic interaction between two soft particles, and the motion of a soft particle in an electric field.

  15. First-principles simulations of electrostatic interactions between dust grains

    SciTech Connect

    Itou, H. Amano, T.; Hoshino, M.

    2014-12-15

    We investigated the electrostatic interaction between two identical dust grains of an infinite mass immersed in homogeneous plasma by employing first-principles N-body simulations combined with the Ewald method. We specifically tested the possibility of an attractive force due to overlapping Debye spheres (ODSs), as was suggested by Resendes et al. [Phys. Lett. A 239, 181–186 (1998)]. Our simulation results demonstrate that the electrostatic interaction is repulsive and even stronger than the standard Yukawa potential. We showed that the measured electric field acting on the grain is highly consistent with a model electrostatic potential around a single isolated grain that takes into account a correction due to the orbital motion limited theory. Our result is qualitatively consistent with the counterargument suggested by Markes and Williams [Phys. Lett. A 278, 152–158 (2000)], indicating the absence of the ODS attractive force.

  16. A model study of sequential enzyme reactions and electrostatic channeling.

    PubMed

    Eun, Changsun; Kekenes-Huskey, Peter M; Metzger, Vincent T; McCammon, J Andrew

    2014-03-14

    We study models of two sequential enzyme-catalyzed reactions as a basic functional building block for coupled biochemical networks. We investigate the influence of enzyme distributions and long-range molecular interactions on reaction kinetics, which have been exploited in biological systems to maximize metabolic efficiency and signaling effects. Specifically, we examine how the maximal rate of product generation in a series of sequential reactions is dependent on the enzyme distribution and the electrostatic composition of its participant enzymes and substrates. We find that close proximity between enzymes does not guarantee optimal reaction rates, as the benefit of decreasing enzyme separation is countered by the volume excluded by adjacent enzymes. We further quantify the extent to which the electrostatic potential increases the efficiency of transferring substrate between enzymes, which supports the existence of electrostatic channeling in nature. Here, a major finding is that the role of attractive electrostatic interactions in confining intermediate substrates in the vicinity of the enzymes can contribute more to net reactive throughput than the directional properties of the electrostatic fields. These findings shed light on the interplay of long-range interactions and enzyme distributions in coupled enzyme-catalyzed reactions, and their influence on signaling in biological systems.

  17. An anisotropic hydrogel with electrostatic repulsion between cofacially aligned nanosheets.

    PubMed

    Liu, Mingjie; Ishida, Yasuhiro; Ebina, Yasuo; Sasaki, Takayoshi; Hikima, Takaaki; Takata, Masaki; Aida, Takuzo

    2015-01-01

    Machine technology frequently puts magnetic or electrostatic repulsive forces to practical use, as in maglev trains, vehicle suspensions or non-contact bearings. In contrast, materials design overwhelmingly focuses on attractive interactions, such as in the many advanced polymer-based composites, where inorganic fillers interact with a polymer matrix to improve mechanical properties. However, articular cartilage strikingly illustrates how electrostatic repulsion can be harnessed to achieve unparalleled functional efficiency: it permits virtually frictionless mechanical motion within joints, even under high compression. Here we describe a composite hydrogel with anisotropic mechanical properties dominated by electrostatic repulsion between negatively charged unilamellar titanate nanosheets embedded within it. Crucial to the behaviour of this hydrogel is the serendipitous discovery of cofacial nanosheet alignment in aqueous colloidal dispersions subjected to a strong magnetic field, which maximizes electrostatic repulsion and thereby induces a quasi-crystalline structural ordering over macroscopic length scales and with uniformly large face-to-face nanosheet separation. We fix this transiently induced structural order by transforming the dispersion into a hydrogel using light-triggered in situ vinyl polymerization. The resultant hydrogel, containing charged inorganic structures that align cofacially in a magnetic flux, deforms easily under shear forces applied parallel to the embedded nanosheets yet resists compressive forces applied orthogonally. We anticipate that the concept of embedding anisotropic repulsive electrostatics within a composite material, inspired by articular cartilage, will open up new possibilities for developing soft materials with unusual functions.

  18. An anisotropic hydrogel with electrostatic repulsion between cofacially aligned nanosheets

    NASA Astrophysics Data System (ADS)

    Liu, Mingjie; Ishida, Yasuhiro; Ebina, Yasuo; Sasaki, Takayoshi; Hikima, Takaaki; Takata, Masaki; Aida, Takuzo

    2015-01-01

    Machine technology frequently puts magnetic or electrostatic repulsive forces to practical use, as in maglev trains, vehicle suspensions or non-contact bearings. In contrast, materials design overwhelmingly focuses on attractive interactions, such as in the many advanced polymer-based composites, where inorganic fillers interact with a polymer matrix to improve mechanical properties. However, articular cartilage strikingly illustrates how electrostatic repulsion can be harnessed to achieve unparalleled functional efficiency: it permits virtually frictionless mechanical motion within joints, even under high compression. Here we describe a composite hydrogel with anisotropic mechanical properties dominated by electrostatic repulsion between negatively charged unilamellar titanate nanosheets embedded within it. Crucial to the behaviour of this hydrogel is the serendipitous discovery of cofacial nanosheet alignment in aqueous colloidal dispersions subjected to a strong magnetic field, which maximizes electrostatic repulsion and thereby induces a quasi-crystalline structural ordering over macroscopic length scales and with uniformly large face-to-face nanosheet separation. We fix this transiently induced structural order by transforming the dispersion into a hydrogel using light-triggered in situ vinyl polymerization. The resultant hydrogel, containing charged inorganic structures that align cofacially in a magnetic flux, deforms easily under shear forces applied parallel to the embedded nanosheets yet resists compressive forces applied orthogonally. We anticipate that the concept of embedding anisotropic repulsive electrostatics within a composite material, inspired by articular cartilage, will open up new possibilities for developing soft materials with unusual functions.

  19. AESOP: A Python Library for Investigating Electrostatics in Protein Interactions.

    PubMed

    Harrison, Reed E S; Mohan, Rohith R; Gorham, Ronald D; Kieslich, Chris A; Morikis, Dimitrios

    2017-05-09

    Electric fields often play a role in guiding the association of protein complexes. Such interactions can be further engineered to accelerate complex association, resulting in protein systems with increased productivity. This is especially true for enzymes where reaction rates are typically diffusion limited. To facilitate quantitative comparisons of electrostatics in protein families and to describe electrostatic contributions of individual amino acids, we previously developed a computational framework called AESOP. We now implement this computational tool in Python with increased usability and the capability of performing calculations in parallel. AESOP utilizes PDB2PQR and Adaptive Poisson-Boltzmann Solver to generate grid-based electrostatic potential files for protein structures provided by the end user. There are methods within AESOP for quantitatively comparing sets of grid-based electrostatic potentials in terms of similarity or generating ensembles of electrostatic potential files for a library of mutants to quantify the effects of perturbations in protein structure and protein-protein association. Copyright © 2017 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  20. A model study of sequential enzyme reactions and electrostatic channeling

    PubMed Central

    Eun, Changsun; Kekenes-Huskey, Peter M.; Metzger, Vincent T.; McCammon, J. Andrew

    2014-01-01

    We study models of two sequential enzyme-catalyzed reactions as a basic functional building block for coupled biochemical networks. We investigate the influence of enzyme distributions and long-range molecular interactions on reaction kinetics, which have been exploited in biological systems to maximize metabolic efficiency and signaling effects. Specifically, we examine how the maximal rate of product generation in a series of sequential reactions is dependent on the enzyme distribution and the electrostatic composition of its participant enzymes and substrates. We find that close proximity between enzymes does not guarantee optimal reaction rates, as the benefit of decreasing enzyme separation is countered by the volume excluded by adjacent enzymes. We further quantify the extent to which the electrostatic potential increases the efficiency of transferring substrate between enzymes, which supports the existence of electrostatic channeling in nature. Here, a major finding is that the role of attractive electrostatic interactions in confining intermediate substrates in the vicinity of the enzymes can contribute more to net reactive throughput than the directional properties of the electrostatic fields. These findings shed light on the interplay of long-range interactions and enzyme distributions in coupled enzyme-catalyzed reactions, and their influence on signaling in biological systems. PMID:24628210

  1. Alternative material to mitigate chrome degradation on high volume ArF layers

    NASA Astrophysics Data System (ADS)

    Ning, Guoxiang; Gopalakrishnan, Selvi; Thamm, Thomas; Oleynik, Nikolay; Ackmann, Paul; Riviere, Remi; Maelzer, Stephanie; Foong, Yee Mei

    2013-09-01

    One of the objectives of a robust optical proximity correction (OPC) model is to simulate the process variation including 3D mask effects or mask models for different mask blanks. Assuming that the data of different reticle blanks is the same, the wafer data should be a close match for the same OPC model. In order to enhance the robustness of the OPC model, the 3D mask effects need to be reduced. A test of this would be to ensure a close match of the so called fingerprints of different reticle blanks at the wafer level. Features for fingerprint test patterns include "critical dimension through pitch" (CDTP), "inverse CDTP", and "linearity patterns" and critical dimension (CD) difference of disposition structures. In this manuscript the proximity matching of implant layers on chrome on glass (COG) and advance binary reticle blanks will be demonstrated. We will also investigate the influence of reticle blank material including reticle process on isolated and dense features upon the proximity matching for 28 nm high volumes ArF layers such as implant and 2X metal layers. The OPC model verification has been done successfully for both bare wafer and full field wafer for implant layers. There is comparable OPC model for advanced binary and COG reticle. Moreover, the wafer critical dimension uniformity (CDU) results show that advance binary has much better wafer CDU then COG. In spite of higher reticle cost when switching over to advanced binary, there is a considerable cost reduction for the wafer fab which includes a 39% savings in total reticle cost as well as cost reduction due to minimal line holds (LH), wafer reworks and scraps due to Chrome degradation.

  2. Electrostatic Screen for Transport of Martian and Lunar Regolith

    NASA Technical Reports Server (NTRS)

    Immer, C.; Starnes, J.; Michalenko, M.; Calle, C. I.; Mazumder, M. K.

    2006-01-01

    The Martian and Lunar Regolith contain fine particulate including those in the size range from 0.5 to 200 micron [1-2]. Martian dust can be transported and deposited by Aeolian processes, including "Dust Devils". Due to the ultra high vacuum (10e-12 Torr), transport of dust on the Moon is solely a result of collision/ballistic motion. Dust obscuration of solar cells is one of the primary factors limiting the duration of Martian missions, including the Mars Exploration Rovers. Dust contamination in vacuum seals is one of the primarily factors that limited lunar excursions during the Apollo missions. Controlled transportation of dust on Mars and the Moon is important for many reasons, including both contamination mitigation and in situ resource utilization (ISRU). Since both the monopole and dipole electrostatic moments result in non-trivial forces on particles in an electrostatic field, dust particles, whether charged or not, can be transported by electrostatic fields. In the electrostatic screen, alternating waveforms of voltage applied to patterned grids of electrodes will transport dust. The authors will show that the canonical methods for transporting dust via electrostatic screen can be readily applied to transport of Martian and Lunar regolith. Experiments have been performed in ambient, low humidity, Martian, and Lunar conditions. Screen parameters have been examined for application to each regolith, such as grid spacing, trace width, grid voltage, pulse pattern, pulse frequency, and coating type. The authors have also developed an electrostatic screen based on optically transparent conductors that can be placed over solar arrays, windows, visors, lenses, etc.

  3. Electrostatic interactions in molecular materials

    NASA Astrophysics Data System (ADS)

    Painelli, Anna; Terenziani, Francesca

    2004-03-01

    Non-additive collective behavior appears in molecular materials as a result of intermolecular interactions. We present a model for interacting polar and polarizable molecules that applies to different supramolecular architectures of donor-π-acceptor molecules. We follow a bottom-up modeling strategy: the detailed analysis of spectroscopic data of solvated molecules leads to the definition of a simple two-state model for the molecular units. Classical electrostatic interactions are then introduced to model molecular clusters. The molecular properties are strickingly affected by supramolecular interactions, as demonstrated by spectroscopic studies. Brand new phenomena, like phase transitions and multielectron transfer, with no counterpart at the molecular level are observed as direct consequences of electrostatic intermolecular interactions.

  4. Effects of low- and high-volume stretching on bench press performance in collegiate football players.

    PubMed

    Molacek, Zachary D; Conley, Donovan S; Evetovich, Tammy K; Hinnerichs, Kristi R

    2010-03-01

    The purpose of this study was to determine the effects of acute low- and high-volume static and proprioceptive neuromuscular facilitation (PNF) stretching on 1-repetition maximum (1RM) bench press. Fifteen healthy male National Collegiate Athletic Association Division II football players (age: 19.9 +/- 1.1 years; weight: 98.89 +/- 13.39 kg; height: 184.2 +/- 5.7 cm; body composition: 14.6 +/- 7.4%; and 1RM bench press: 129.7 +/- 3.3 kg) volunteered to participate in the study. Subjects completed 5 different stretching protocols integrated with a 1RM dynamic warm-up routine followed by 1RM testing in randomly assigned order. The protocols included (a) nonstretching (NS), (b) low-volume PNF stretching (LVPNFS), (c) high-volume PNF stretching (HVPNFS), (d) low-volume static stretching (LVSS), and (d) high-volume static stretching (HVSS). Two and 5 sets of stretching were completed for the low- and high-volume protocols, respectively. The stretching protocols targeted triceps and chest/shoulder muscle groups using 2 separate exercises. There were no significant differences in 1RM bench press performance (p > 0.05) among any of the stretching protocols NS (129.7 +/- 3.3 kg), LVPNFS (128.9 +/- 3.8 kg), HVPNFS (128.3 +/- 3.7 kg), LVSS (129.7 +/- 3.7 kg), and HVSS (128.2 +/- 3.7 kg). We conclude that low- and high-volume PNF and static stretching have no significant acute effect on 1RM bench press in resistance-trained collegiate football players. This suggests that resistance-trained athletes can include either (a) a dynamic warm-up with no stretching or (b) a dynamic warm-up in concert with low- or high-volume static or PNF flexibility exercises before maximal upper body isotonic resistance-training lifts, if adequate rest is allowed before performance.

  5. A Nonlinear Elasticity Model of Macromolecular Conformational Change Induced by Electrostatic Forces

    PubMed Central

    Zhou, Y. C.; Holst, Michael; McCammon, J. Andrew

    2008-01-01

    In this paper we propose a nonlinear elasticity model of macromolecular conformational change (deformation) induced by electrostatic forces generated by an implicit solvation model. The Poisson-Boltzmann equation for the electrostatic potential is analyzed in a domain varying with the elastic deformation of molecules, and a new continuous model of the electrostatic forces is developed to ensure solvability of the nonlinear elasticity equations. We derive the estimates of electrostatic forces corresponding to four types of perturbations to an electrostatic potential field, and establish the existance of an equilibrium configuration using a fixed-point argument, under the assumption that the change in the ionic strength and charges due to the additional molecules causing the deformation are sufficiently small. The results are valid for elastic models with arbitrarily complex dielectric interfaces and cavities, and can be generalized to large elastic deformation caused by high ionic strength, large charges, and strong external fields by using continuation methods. PMID:19461946

  6. A Nonlinear Elasticity Model of Macromolecular Conformational Change Induced by Electrostatic Forces.

    PubMed

    Zhou, Y C; Holst, Michael; McCammon, J Andrew

    2008-04-01

    In this paper we propose a nonlinear elasticity model of macromolecular conformational change (deformation) induced by electrostatic forces generated by an implicit solvation model. The Poisson-Boltzmann equation for the electrostatic potential is analyzed in a domain varying with the elastic deformation of molecules, and a new continuous model of the electrostatic forces is developed to ensure solvability of the nonlinear elasticity equations. We derive the estimates of electrostatic forces corresponding to four types of perturbations to an electrostatic potential field, and establish the existance of an equilibrium configuration using a fixed-point argument, under the assumption that the change in the ionic strength and charges due to the additional molecules causing the deformation are sufficiently small. The results are valid for elastic models with arbitrarily complex dielectric interfaces and cavities, and can be generalized to large elastic deformation caused by high ionic strength, large charges, and strong external fields by using continuation methods.

  7. Defining Protein Electrostatic Recognition Processes

    DTIC Science & Technology

    1989-11-30

    making and aligning expanded molecular dot surfaces for each molecule and checking these surfaces for interpenetration. The program TURNIP used these...year of this contract, we have developed and optimized the TURNIP program, which consists of two parts. First, the electrostatic pctcntia! due to mo...supercomputer where the rotation and translation of molecule 2 occurs. The program TURNIP is written in the programming language C, and has been optimized

  8. Defining Protein Electrostatic Recognition Processes

    DTIC Science & Technology

    1992-01-01

    approach. We developed the TURNIP program to determine the most favorable precollision orientations for two molecules by systematic search of all...orientations and evaluation of the resulting electrostatic interactions. TURNIP was applied to the transient interaction between two electron transfer...region of cytochrome c with the negative patch of plastocyanin, consistent with experimental data. Application of TURNIP to the formation of the stable

  9. The use of Whatman-41 filters for high volume air sampling

    NASA Technical Reports Server (NTRS)

    Neustadter, H. E.; Sidik, S. M.; King, R. B.; Fordyce, J. S.; Burr, J. C.

    1975-01-01

    The feasibility of using W41 filter media on a routine TSP high-volume monitoring network was determined by comparison with glass fiber (GF) filtering. Results indicate that suspended particulate samples from GF filters averaged slightly, but not significantly, higher than those from Whatman-41 filters. Some extra handling procedures were required to avoid errors due to the hygroscopic nature of W41 filters; these added procedures are not overly burdensome, however, and they allow the performance of analytical work, thus extending the capabilities of high-volume sampling. It was demonstrated that W41 filters are practical for air quality monitoring and elemental analysis in environments similar to Cleveland's.

  10. Performance enhancement of direct ethanol fuel cell using Nafion composites with high volume fraction of titania

    NASA Astrophysics Data System (ADS)

    Matos, B. R.; Isidoro, R. A.; Santiago, E. I.; Fonseca, F. C.

    2014-12-01

    The present study reports on the performance enhancement of direct ethanol fuel cell (DEFC) at 130 °C with Nafion-titania composite electrolytes prepared by sol-gel technique and containing high volume fractions of the ceramic phase. It is found that for high volume fractions of titania (>10 vol%) the ethanol uptake of composites is largely reduced while the proton conductivity at high-temperatures is weakly dependent on the titania content. Such tradeoff between alcohol uptake and conductivity resulted in a boost of DEFC performance at high temperatures using Nafion-titania composites with high fraction of the inorganic phase.

  11. Photon induced tunneling of electron through a graphene electrostatic barrier

    SciTech Connect

    Biswas, R.; Sinha, C.

    2013-11-14

    The influence of an external intense laser field on the tunneling transport (ballistic) of the Dirac fermions through a monolayer graphene electrostatic barrier is studied in the framework of the Floquet approach for a continuous wave, linearly polarized, monochromatic laser. The Klein tunneling is shown to be suppressed by the irradiation of a strong laser field, arising due to breaking of chiral symmetry. The symmetric nature of the field free angular transmission spectrum around the normal to the well-barrier interface is destroyed due to the additional coupling between the pseudo-spin and the time dependent vector potential. The energy distribution of the tunneling spectrum displays Fano resonance which is absent for a laser assisted conventional electrostatic barrier but similar to the case of quantum well structures, providing an optical tool to identify field free quasi bound states inside the graphene nanostructures.

  12. KSC Electrostatic Discharge (ESD) Issues

    NASA Technical Reports Server (NTRS)

    Buhler, Charles

    2008-01-01

    Discussion of key electrostatic issues that have arisen during the past few years at KSC that the Electrostatics Laboratory has studied. The lab has studied in depth the Space Shuttle's Thermal Control System Blankets, the International Space Station Thermal Blanket, the Pan/Tilt Camera Blankets, the Kapton Purge Barrier Curtain, the Aclar Purge Barrier Curtain, the Thrust Vector Controller Blankets, the Tyvek Reaction Control System covers, the AID-PAK and FLU-9 pyro inflatable devices, the Velostat Solid Rocket Booster mats, and the SCAPE suits. In many cases these materials are insulating meaning that they might be a source of unsafe levels of electrostatic discharge (ESD). For each, the lab provided in-depth testing of each material within its current configuration to ensure that it does not cause an ESD concern that may violate the safety of the astronauts, the workers and equipment for NASA. For example the lab provides unique solutions and testing such as Spark Incendivity Testing that checks whether a material is capable of generating a spark strong enough to ignite a flammable gas. The lab makes recommendations to changes in specifications, procedures, and material if necessary. The lab also consults with a variety of non-safety related ESD issues for the agency.

  13. Quantitative nanoscale electrostatics of viruses.

    PubMed

    Hernando-Pérez, M; Cartagena-Rivera, A X; Lošdorfer Božič, A; Carrillo, P J P; San Martín, C; Mateu, M G; Raman, A; Podgornik, R; de Pablo, P J

    2015-11-07

    Electrostatics is one of the fundamental driving forces of the interaction between biomolecules in solution. In particular, the recognition events between viruses and host cells are dominated by both specific and non-specific interactions and the electric charge of viral particles determines the electrostatic force component of the latter. Here we probe the charge of individual viruses in liquid milieu by measuring the electrostatic force between a viral particle and the Atomic Force Microscope tip. The force spectroscopy data of co-adsorbed ϕ29 bacteriophage proheads and mature virions, adenovirus and minute virus of mice capsids is utilized for obtaining the corresponding density of charge for each virus. The systematic differences of the density of charge between the viral particles are consistent with the theoretical predictions obtained from X-ray structural data. Our results show that the density of charge is a distinguishing characteristic of each virus, depending crucially on the nature of the viral capsid and the presence/absence of the genetic material.

  14. Electrostatic chains driven by nonuniform lower hybrid pump

    NASA Astrophysics Data System (ADS)

    Vranjes, J.; Jovanovic, D.

    1997-01-01

    We study the parametric interaction of a nonuniform long-wavelength lower hybrid (LH) wave propagating almost perpendicularly to the magnetic field lines, with low frequency density perturbations. Neglecting perturbations of the strong LH wave acting as a pump, we show that for a specific profile of its amplitude, a LH pump can excite electrostatic vortex chains propagating perpendicularly both to the magnetic field and the direction of the pump gradient.

  15. Electrostatic energy analyzers for high energy charged particle beams

    NASA Astrophysics Data System (ADS)

    Ilyin, A. M.; Ilyina, I. A.

    2016-02-01

    The electrostatic energy analyzers for high energy charged particle beams emitted from extended large-size objects as well as from remote point sources are proposed. Results of the analytical trajectory solutions in ideal cylindrical field provide focusing characteristics for both configurations. The instruments possess of simple compact design, based on an ideal cylindrical field with entrance window arranged in the end-boundary between electrodes and can be used for measurements in space technologies, plasma and nuclear physics.

  16. Electrostatic ion cyclotron velocity shear instability

    NASA Technical Reports Server (NTRS)

    Lemons, D. S.; Winske, D.; Gary, S. P.

    1992-01-01

    A local electrostatic dispersion equation is derived for a shear flow perpendicular to an ambient magnetic field, which includes all kinetic effects and involves only one important parameter. The dispersion equation is cast in the form of Gordeyev integrals and is solved numerically. Numerical solutions indicate that an ion cyclotron instability is excited. The instability occurs roughly at multiples of the ion cyclotron frequency (modified by the shear), with the growth rate or the individual harmonics overlapping in the wavenumber. At large values of the shear parameter, the instability is confined to long wavelengths, but at smaller shear, a second distinct branch at shorter wavelengths also appears. The properties of the instability obtained are compared with those obtained in the nonlocal limit by Ganguli et al. (1985, 1988).

  17. Probe Measurements of Electrostatic Fluctuations in LDX

    NASA Astrophysics Data System (ADS)

    Ortiz, E. E.; Mauel, M. E.; Garnier, D. T.; Hansen, A. K.; Levitt, B. J.; Kesner, J.; Boxer, A.; Ellsworth, J. L.; Karim, I.; Mahar, S.; Roach, A. H.; Zimmermann, M.

    2004-11-01

    Electrostatic fluctuations play an important role in the equilibrium and stability of a high-beta plasma confined in a dipolar magnetic field. Initial plasma experiments in LDX will use movable edge probes to measure plasma potential, plasma characteristics, and plasma mass flow. Three probe systems have been installed: a triple Langmuir probe (constructed of 1 cm long, 0.5 mm dia. tungsten wire probe tips), an emissive probe (constructed of 0.9 cm long, 1 mm dia. thoriated tungsten wire), and a Mach probe (constructed with two 0.7 cm long, 1.5 mm dia. tungsten wires). Each probe is mounted on an adjustable feed-through capable of scanning parameters along a 40 cm cord at the plasma edge. Initial measurements and interpretations from first plasma experiments will be presented.

  18. Invited Review Article: The electrostatic plasma lens

    SciTech Connect

    Goncharov, Alexey

    2013-02-15

    The fundamental principles, experimental results, and potential applications of the electrostatic plasma lens for focusing and manipulating high-current, energetic, heavy ion beams are reviewed. First described almost 50 years ago, this optical beam device provides space charge neutralization of the ion beam within the lens volume, and thus provides an effective and unique tool for focusing high current beams where a high degree of neutralization is essential to prevent beam blow-up. Short and long lenses have been explored, and a lens in which the magnetic field is provided by rare-earth permanent magnets has been demonstrated. Applications include the use of this kind of optical tool for laboratory ion beam manipulation, high dose ion implantation, heavy ion accelerator injection, in heavy ion fusion, and other high technology.

  19. Processes and applications of electrostatic fiber formation

    NASA Astrophysics Data System (ADS)

    Rutledge, Gregory C.

    2008-12-01

    'Electrospinning' is an electrohydrodynamic jetting process that enables the production of continuous fibers, tubes and wires with diameters as small as 10 nm. The process itself is dependent upon electrostatic interactions such as charge-charge repulsion and charge-field interaction. The interplay of charge repulsion, viscoelasticity and surface tension gives rise to interesting electrohydrodynamic phenomena that challenge fundamental understanding as well as practical implementation and quality control in the final fibers. The morphology and diameter of these fibers can be understood and controlled through manipulation of fluid properties and operating parameters. The fibers thus produced are illustrative of nanotechnology in a 1-dimensional form, and have inspired considerable activity in the research community into their potential applications. Proposed uses range from high performance filtration media and membranes, to sensors and actuators, to medical devices and drug delivery vehicles. Two examples, tissue scaffold engineering and superhydrophobicity, are illustrated here.

  20. Operating High-Volume Air Samplers. Module 3. Vocational Education Training in Environmental Health Sciences.

    ERIC Educational Resources Information Center

    Consumer Dynamics Inc., Rockville, MD.

    This module, one of 25 on vocational education training for careers in environmental health occupations, contains self-instructional materials on operating high-volume air samplers. Following guidelines for students and instructors and an introduction that explains what the student will learn are three lessons: (1) disassembling the high-volume…