Beam quality corrections for parallel-plate ion chambers in electron reference dosimetry

NASA Astrophysics Data System (ADS)

Zink, K.; Wulff, J.

2012-04-01

Current dosimetry protocols (AAPM, IAEA, IPEM, DIN) recommend parallel-plate ionization chambers for dose measurements in clinical electron beams. This study presents detailed Monte Carlo simulations of beam quality correction factors for four different types of parallel-plate chambers: NACP-02, Markus, Advanced Markus and Roos. These chambers differ in constructive details which should have notable impact on the resulting perturbation corrections, hence on the beam quality corrections. The results reveal deviations to the recommended beam quality corrections given in the IAEA TRS-398 protocol in the range of 0%-2% depending on energy and chamber type. For well-guarded chambers, these deviations could be traced back to a non-unity and energy-dependent wall perturbation correction. In the case of the guardless Markus chamber, a nearly energy-independent beam quality correction is resulting as the effects of wall and cavity perturbation compensate each other. For this chamber, the deviations to the recommended values are the largest and may exceed 2%. From calculations of type-B uncertainties including effects due to uncertainties of the underlying cross-sectional data as well as uncertainties due to the chamber material composition and chamber geometry, the overall uncertainty of calculated beam quality correction factors was estimated to be <0.7%. Due to different chamber positioning recommendations given in the national and international dosimetry protocols, an additional uncertainty in the range of 0.2%-0.6% is present. According to the IAEA TRS-398 protocol, the uncertainty in clinical electron dosimetry using parallel-plate ion chambers is 1.7%. This study may help to reduce this uncertainty significantly.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schneider, T

Purpose: Since 2008 the Physikalisch-Technische Bundesanstalt (PTB) has been offering the calibration of {sup 125}I-brachytherapy sources in terms of the reference air-kerma rate (RAKR). The primary standard is a large air-filled parallel-plate extrapolation chamber. The measurement principle is based on the fact that the air-kerma rate is proportional to the increment of ionization per increment of chamber volume at chamber depths greater than the range of secondary electrons originating from the electrode x{sub 0}. Methods: Two methods for deriving the RAKR from the measured ionization charges are: (1) to determine the RAKR from the slope of the linear fit tomore » the so-called ’extrapolation curve’, the measured ionization charges Q vs. plate separations x or (2) to differentiate Q(x) and to derive the RAKR by a linear extrapolation towards zero plate separation. For both methods, correcting the measured data for all known influencing effects before the evaluation method is applied is a precondition. However, the discrepancy of their results is larger than the uncertainty given for the determination of the RAKR with both methods. Results: A new approach to derive the RAKR from the measurements is investigated as an alternative. The method was developed from the ground up, based on radiation transport theory. A conversion factor C(x{sub 1}, x{sub 2}) is applied to the difference of charges measured at the two plate separations x{sub 1} and x{sub 2}. This factor is composed of quotients of three air-kerma values calculated for different plate separations in the chamber: the air kerma Ka(0) for plate separation zero, and the mean air kermas at the plate separations x{sub 1} and x{sub 2}, respectively. The RAKR determined with method (1) yields 4.877 µGy/h, and with method (2) 4.596 µGy/h. The application of the alternative approach results in 4.810 µGy/h. Conclusion: The alternative method shall be established in the future.« less

Quantitative Thin-Layer Chromatography/Mass Spectrometry Analysis of Caffeine Using a Surface Sampling Probe Electrospray Ionization Tandem Mass Spectrometry System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ford, Michael J; Deibel, Michael A.; Tomkins, Bruce A

Quantitative determination of caffeine on reversed-phase C8 thin-layer chromatography plates using a surface sampling electrospray ionization system with tandem mass spectrometry detection is reported. The thin-layer chromatography/electrospray tandem mass spectrometry method employed a deuterium-labeled caffeine internal standard and selected reaction monitoring detection. Up to nine parallel caffeine bands on a single plate were sampled in a single surface scanning experiment requiring 35 min at a surface scan rate of 44 {mu}m/s. A reversed-phase HPLC/UV caffeine assay was developed in parallel to assess the mass spectrometry method performance. Limits of detection for the HPLC/UV and thin-layer chromatography/electrospray tandem mass spectrometry methodsmore » determined from the calibration curve statistics were 0.20 ng injected (0.50 {mu}L) and 1.0 ng spotted on the plate, respectively. Spike recoveries with standards and real samples ranged between 97 and 106% for both methods. The caffeine content of three diet soft drinks (Diet Coke, Diet Cherry Coke, Diet Pepsi) and three diet sport drinks (Diet Turbo Tea, Speed Stack Grape, Speed Stack Fruit Punch) was measured. The HPLC/UV and mass spectrometry determinations were in general agreement, and these values were consistent with the quoted values for two of the three diet colas. In the case of Diet Cherry Coke and the diet sports drinks, the determined caffeine amounts using both methods were consistently higher (by 8% or more) than the literature values.« less

Investigation of electron-loss and photon scattering correction factors for FAC-IR-300 ionization chamber

NASA Astrophysics Data System (ADS)

Mohammadi, S. M.; Tavakoli-Anbaran, H.; Zeinali, H. Z.

2017-02-01

The parallel-plate free-air ionization chamber termed FAC-IR-300 was designed at the Atomic Energy Organization of Iran, AEOI. This chamber is used for low and medium X-ray dosimetry on the primary standard level. In order to evaluate the air-kerma, some correction factors such as electron-loss correction factor (ke) and photon scattering correction factor (ksc) are needed. ke factor corrects the charge loss from the collecting volume and ksc factor corrects the scattering of photons into collecting volume. In this work ke and ksc were estimated by Monte Carlo simulation. These correction factors are calculated for mono-energy photon. As a result of the simulation data, the ke and ksc values for FAC-IR-300 ionization chamber are 1.0704 and 0.9982, respectively.

Surface dose measurements with commonly used detectors: a consistent thickness correction method.

PubMed

Reynolds, Tatsiana A; Higgins, Patrick

2015-09-08

The purpose of this study was to review application of a consistent correction method for the solid state detectors, such as thermoluminescent dosimeters (chips (cTLD) and powder (pTLD)), optically stimulated detectors (both closed (OSL) and open (eOSL)), and radiochromic (EBT2) and radiographic (EDR2) films. In addition, to compare measured surface dose using an extrapolation ionization chamber (PTW 30-360) with other parallel plate chambers RMI-449 (Attix), Capintec PS-033, PTW 30-329 (Markus) and Memorial. Measurements of surface dose for 6MV photons with parallel plate chambers were used to establish a baseline. cTLD, OSLs, EDR2, and EBT2 measurements were corrected using a method which involved irradiation of three dosimeter stacks, followed by linear extrapolation of individual dosimeter measurements to zero thickness. We determined the magnitude of correction for each detector and compared our results against an alternative correction method based on effective thickness. All uncorrected surface dose measurements exhibited overresponse, compared with the extrapolation chamber data, except for the Attix chamber. The closest match was obtained with the Attix chamber (-0.1%), followed by pTLD (0.5%), Capintec (4.5%), Memorial (7.3%), Markus (10%), cTLD (11.8%), eOSL (12.8%), EBT2 (14%), EDR2 (14.8%), and OSL (26%). Application of published ionization chamber corrections brought all the parallel plate results to within 1% of the extrapolation chamber. The extrapolation method corrected all solid-state detector results to within 2% of baseline, except the OSLs. Extrapolation of dose using a simple three-detector stack has been demonstrated to provide thickness corrections for cTLD, eOSLs, EBT2, and EDR2 which can then be used for surface dose measurements. Standard OSLs are not recommended for surface dose measurement. The effective thickness method suffers from the subjectivity inherent in the inclusion of measured percentage depth-dose curves and is not recommended for these types of measurements.

Surface dose measurements with commonly used detectors: a consistent thickness correction method

PubMed Central

Higgins, Patrick

2015-01-01

The purpose of this study was to review application of a consistent correction method for the solid state detectors, such as thermoluminescent dosimeters (chips (cTLD) and powder (pTLD)), optically stimulated detectors (both closed (OSL) and open (eOSL)), and radiochromic (EBT2) and radiographic (EDR2) films. In addition, to compare measured surface dose using an extrapolation ionization chamber (PTW 30‐360) with other parallel plate chambers RMI‐449 (Attix), Capintec PS‐033, PTW 30‐329 (Markus) and Memorial. Measurements of surface dose for 6 MV photons with parallel plate chambers were used to establish a baseline. cTLD, OSLs, EDR2, and EBT2 measurements were corrected using a method which involved irradiation of three dosimeter stacks, followed by linear extrapolation of individual dosimeter measurements to zero thickness. We determined the magnitude of correction for each detector and compared our results against an alternative correction method based on effective thickness. All uncorrected surface dose measurements exhibited overresponse, compared with the extrapolation chamber data, except for the Attix chamber. The closest match was obtained with the Attix chamber (−0.1%), followed by pTLD (0.5%), Capintec (4.5%), Memorial (7.3%), Markus (10%), cTLD (11.8%), eOSL (12.8%), EBT2 (14%), EDR2 (14.8%), and OSL (26%). Application of published ionization chamber corrections brought all the parallel plate results to within 1% of the extrapolation chamber. The extrapolation method corrected all solid‐state detector results to within 2% of baseline, except the OSLs. Extrapolation of dose using a simple three‐detector stack has been demonstrated to provide thickness corrections for cTLD, eOSLs, EBT2, and EDR2 which can then be used for surface dose measurements. Standard OSLs are not recommended for surface dose measurement. The effective thickness method suffers from the subjectivity inherent in the inclusion of measured percentage depth‐dose curves and is not recommended for these types of measurements. PACS number: 87.56.‐v PMID:26699319

MEASUREMENT OF THE INTENSITY OF THE PROTON BEAM OF THE HARVARD UNIVERSITY SYNCHROCYCLOTRON FOR ENERGY-SPECTRAL MEASUREMENTS OF NUCLEAR SECONDARIES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Santoro, R.T.; Peelle, R.W.

1964-03-01

Two thin helium-filled parallel-plate ionization chambers were designed for use in continuously monitoring the 160-Mev proton beam of the Harvard University Synchrocyclotron over an intensity range from 10/sup 5/ to 10/sup 10/ protons/ sec. The ionlzation chambers were calibrated by two independert methods. In four calibrations the charge collected in the ionization chambers was compared with that deposited in a Faraday cup which followed the ionization chambers in the proton beam. In a second method, a calibration was made by individually counting beam protons with a pnir of thin scintillation detectors. The ionization chamber response was found to be flatmore » within 2% for a five-decade range of beam intensity. Comparison of the Faraday-cup calibrations with that from proton counting shows agreement to within 5%, which is considered satisfactory. The experimental results were also in agreement, within estimated errors, with the ionization chamber response calculated using an accepted value of the average energy loss per ion pair for helium. A slow shift in the calibrations with time is ascribed to a gradual contamination of the helium of the chambers by air leakage. (auth)« less

Investigation of thermal and temporal responses of ionization chambers in radiation dosimetry.

PubMed

AlMasri, Hussein; Funyu, Akira; Kakinohana, Yasumasa; Murayama, Sadayuki

2012-07-01

The ionization chamber is a primary dosimeter that is used in radiation dosimetry. Generally, the ion chamber response requires temperature/pressure correction according to the ideal gas law. However, this correction does not consider the thermal volume effect of chambers. The temporal and thermal volume effects of various chambers (CC01, CC13, NACP parallel-plate, PTW) with different wall and electrode materials have been studied in a water phantom. Measurements were done after heating the water with a suitable heating system, and chambers were submerged for a sufficient time to allow for temperature equilibrium. Temporal results show that all chambers equilibrate quickly in water. The equilibration time was between 3 and 5 min for all chambers. Thermal results show that all chambers expanded in response to heating except for the PTW, which contracted. This might be explained by the differences in the volumes of all chambers and also by the difference in wall material composition of PTW from the other chambers. It was found that the smallest chamber, CC01, showed the greatest expansion. The magnitude of the expansion was ~1, 0.8, and 0.9% for CC01, CC13, and parallel-plate chambers, respectively, in the temperature range of 295-320 K. The magnitude of the detected contraction was <0.3% for PTW in the same temperature range. For absolute dosimetry, it is necessary to make corrections for the ion chamber response, especially for small ion chambers like the CC01. Otherwise, room and water phantom temperatures should remain within a close range.

Low pressure spark gap triggered by an ion diode

DOEpatents

Prono, Daniel S.

1985-01-01

Spark gap apparatus for use as an electric switch operating at high voltage, high current and high repetition rate. Mounted inside a housing are an anode, cathode and ion plate. An ionizable fluid is pumped through the chamber of the housing. A pulse of current to the ion plate causes ions to be emitted by the ion plate, which ions move into and ionize the fluid. Electric current supplied to the anode discharges through the ionized fluid and flows to the cathode. Current stops flowing when the current source has been drained. The ionized fluid recombines into its initial dielectric ionizable state. The switch is now open and ready for another cycle.

Low-pressure spark gap triggered by an ion diode

DOEpatents

Prono, D.S.

1982-08-31

Spark gap apparatus for use as an electric switch operating at high voltage, high current and high repetition rate. Mounted inside a housing are an anode, cathode and ion plate. An ionizable fluid is pumped through the chamber of the housing. A pulse of current to the ion plate causes ions to be emitted by the ion plate, which ions move into and ionize the fluid. Electric current supplied to the anode discharges through the ionized fluid and flows to the cathode. Current stops flowing when the current source has been drained. The ionized fluid recombines into its initial dielectric ionizable state. The switch is now open and ready for another cycle.

Parallel Plate System for Collecting Data Used to Determine Viscosity

NASA Technical Reports Server (NTRS)

Ethridge, Edwin C. (Inventor); Kaukler, William (Inventor)

2013-01-01

A parallel-plate system collects data used to determine viscosity. A first plate is coupled to a translator so that the first plate can be moved along a first direction. A second plate has a pendulum device coupled thereto such that the second plate is suspended above and parallel to the first plate. The pendulum device constrains movement of the second plate to a second direction that is aligned with the first direction and is substantially parallel thereto. A force measuring device is coupled to the second plate for measuring force along the second direction caused by movement of the second plate.

Portable Aerosol Contaminant Extractor

DOEpatents

Carlson, Duane C.; DeGange, John J.; Cable-Dunlap, Paula

2005-11-15

A compact, portable, aerosol contaminant extractor having ionization and collection sections through which ambient air may be drawn at a nominal rate so that aerosol particles ionized in the ionization section may be collected on charged plate in the collection section, the charged plate being readily removed for analyses of the particles collected thereon.

Gas chromatography fractionation platform featuring parallel flame-ionization detection and continuous high-resolution analyte collection in 384-well plates.

PubMed

Jonker, Willem; Clarijs, Bas; de Witte, Susannah L; van Velzen, Martin; de Koning, Sjaak; Schaap, Jaap; Somsen, Govert W; Kool, Jeroen

2016-09-02

Gas chromatography (GC) is a superior separation technique for many compounds. However, fractionation of a GC eluate for analyte isolation and/or post-column off-line analysis is not straightforward, and existing platforms are limited in the number of fractions that can be collected. Moreover, aerosol formation may cause serious analyte losses. Previously, our group has developed a platform that resolved these limitations of GC fractionation by post-column infusion of a trap solvent prior to continuous small-volume fraction collection in a 96-wells plate (Pieke et al., 2013 [17]). Still, this GC fractionation set-up lacked a chemical detector for the on-line recording of chromatograms, and the introduction of trap solvent resulted in extensive peak broadening for late-eluting compounds. This paper reports advancements to the fractionation platform allowing flame ionization detection (FID) parallel to high-resolution collection of a full GC chromatograms in up to 384 nanofractions of 7s each. To this end, a post-column split was incorporated which directs part of the eluate towards FID. Furthermore, a solvent heating device was developed for stable delivery of preheated/vaporized trap solvent, which significantly reduced band broadening by post-column infusion. In order to achieve optimal analyte trapping, several solvents were tested at different flow rates. The repeatability of the optimized GC fraction collection process was assessed demonstrating the possibility of up-concentration of isolated analytes by repetitive analyses of the same sample. The feasibility of the improved GC fractionation platform for bioactivity screening of toxic compounds was studied by the analysis of a mixture of test pesticides, which after fractionation were subjected to a post-column acetylcholinesterase (AChE) assay. Fractions showing AChE inhibition could be unambiguously correlated with peaks from the parallel-recorded FID chromatogram. Copyright © 2016 Elsevier B.V. All rights reserved.

Proton-impact ionization cross sections of adenine measured at 0.5 and 2.0 MeV by electron spectroscopy

NASA Astrophysics Data System (ADS)

Iriki, Y.; Kikuchi, Y.; Imai, M.; Itoh, A.

2011-11-01

Double-differential ionization cross sections (DDCSs) of vapor-phase adenine molecules (C5H5N5) by 0.5- and 2.0-MeV proton impact have been measured by the electron spectroscopy method. Electrons ejected from adenine were analyzed by a 45∘ parallel-plate electrostatic spectrometer over an energy range of 1.0-1000 eV at emission angles from 15∘ to 165∘. Single-differential cross sections (SDCSs) and total ionization cross sections (TICSs) were also deduced. It was found from the Platzman plot, defined as SDCSs divided by the classical Rutherford knock-on cross sections per target electron, that the SDCSs at higher electron energies are proportional to the total number of valence electrons (50) of adenine, while those at low-energy electrons are highly enhanced due to dipole and higher-order interactions. The present results of TICS are in fairly good agreement with recent classical trajectory Monte Carlo calculations, and moreover, a simple analytical formula gives nearly equivalent cross sections in magnitude at the incident proton energies investigated.

Sci-Sat AM: Radiation Dosimetry and Practical Therapy Solutions - 06: Investigation of an absorbed dose to water formalism for a miniature low-energy x-ray source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Watson, Peter; Seuntjens, Jan

Purpose: We present a formalism for calculating the absorbed dose to water from a miniature x-ray source (The INTRABEAM system, Carl Zeiss), using a parallel-plate ionization chamber calibrated in terms of air-kerma. Monte Carlo calculations were performed to derive a chamber conversion factor (C{sub Q}) from reference air-kerma to dose to water for the INTRABEAM. C{sub Q} was investigated as a function of depth in water, and compared with the manufacturer’s reported value. The effect of chamber air cavity dimension tolerance was also investigated. Methods: Air-kerma (A{sub k}) from a reference beam was calculated using the EGSnrc user code cavity.more » Using egs-chamber, a model of a PTW 34013 parallel-plate ionization chamber was created according to manufacturer specifications. The dose to the chamber air cavity (D{sub gas}) was simulated both in-air (with reference beam) and in-water (with INTRABEAM source). Dose to a small water voxel (D{sub w}) was also calculated. C{sub Q} was derived from these quantities. Results: C{sub Q} was found to vary by up to 15% (1.30 vs 1.11) between chamber dimension extremes. The agreement between chamber C{sub Q} was found to improve with increasing depth in water. However, in all cases investigated, C{sub Q} was larger than the manufacturer reported value of 1.054. Conclusions: Our results show that cavity dimension tolerance has a significant effect on C{sub Q}, with differences as large as 15%. In all cases considered, C{sub Q} was found to be larger than the reported value of 1.054. This suggests that the recommended calculation underestimates the dose to water.« less

A rocket-borne electrostatic analyzer for measurement of energetic particle flux

NASA Technical Reports Server (NTRS)

Pozzi, M. A.; Smith, L. G.; Voss, H. D.

1979-01-01

A rocket-borne electrostatic analyzer experiment is described. It is used to measure energetic particle flux (0.9 to 14 keV) in the nighttime midlatitude E region. Energetic particle precipitation is believed to be a significant nighttime ionization source, particularly during times of high geomagnetic activity. The experiment was designed for use in the payload of a Nike Apache sounding rocket. The electrostatic analyzer employs two cylindrical parallel plates subtending a central angle of 90 deg. The voltage waveform supplied to the plates is a series of steps synchronized to the spin of the payload during flight. Both positive and negative voltages are provided, extending the detection capabilities of the instrument to both electrons and protons (and positive ions). The development, construction and operation of the instrument is described together with a preliminary evaluation of its performance in a rocket flight.

Spectroscopic diagnostics of plume rebound and shockwave dynamics of confined aluminum laser plasma plumes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yeates, P.; Kennedy, E. T.; School of Physical Sciences, Dublin City University

2011-06-15

Generation and expansion dynamics of aluminum laser plasma plumes generated between parallel plates of varying separation ({Delta}Z = 2.0, 3.2, 4.0, and 5.6 mm), which confined plume expansion normal to the ablation surface, were diagnosed. Space and time resolved visible emission spectroscopy in the spectral range {lambda} = 355-470 nm and time gated visible imaging were employed to record emission spectra and plume dynamics. Space and time resolved profiles of N{sub e} (the electron density), T{sub e} (the electron temperature), and T{sub ionz} (the ionization temperature) were compared for different positions in the plasma plume. Significant modifications of the profilesmore » of the above parameters were observed for plasma-surface collisions at the inner surface of the front plate, which formed a barrier to the free expansion of the plasma plume generated by the laser light on the surface of the back plate. Shockwave generation at the collision interface resulted in delayed compression of the low-density plasma plume near the inner ablation surface, at late stages in the plasma history. Upon exiting the cavity formed by the two plates, through an aperture in the front plate, the plasma plume underwent a second phase of free expansion.« less

Thin-layer chromatography and mass spectrometry coupled using proximal probe thermal desorption with electrospray or atmospheric pressure chemical ionization.

PubMed

Ovchinnikova, Olga S; Van Berkel, Gary J

2010-06-30

An atmospheric pressure proximal probe thermal desorption sampling method coupled with secondary ionization by electrospray or atmospheric pressure chemical ionization was demonstrated for the mass spectrometric analysis of a diverse set of compounds (dyestuffs, pharmaceuticals, explosives and pesticides) separated on various high-performance thin-layer chromatography plates. Line scans along or through development lanes on the plates were carried out by moving the plate relative to a stationary heated probe positioned close to or just touching the stationary phase surface. Vapors of the compounds thermally desorbed from the surface were drawn into the ionization region of a combined electrospray ionization/atmospheric pressure chemical ionization source where they merged with reagent ions and/or charged droplets from a corona discharge or an electrospray emitter and were ionized. The ionized components were then drawn through the atmospheric pressure sampling orifice into the vacuum region of a triple quadrupole mass spectrometer and detected using full scan, single ion monitoring, or selected reaction monitoring mode. Studies of variable parameters and performance metrics including the proximal probe temperature, gas flow rate into the ionization region, surface scan speed, read-out resolution, detection limits, and surface type are discussed.

Fringe Capacitance of a Parallel-Plate Capacitor.

ERIC Educational Resources Information Center

Hale, D. P.

1978-01-01

Describes an experiment designed to measure the forces between charged parallel plates, and determines the relationship among the effective electrode area, the measured capacitance values, and the electrode spacing of a parallel plate capacitor. (GA)

Determination of the fast-neutron-induced fission cross-section of 242Pu at nELBE

NASA Astrophysics Data System (ADS)

Kögler, Toni; Beyer, Roland; Junghans, Arnd R.; Schwengner, Ronald; Wagner, Andreas

2018-03-01

The fast-neutron-induced fission cross section of 242Pu was determined in the energy range of 0.5 MeV to 10MeV at the neutron time-of-flight facility nELBE. Using a parallel-plate fission ionization chamber this quantity was measured relative to 235U(n,f). The number of target nuclei was thereby calculated by means of measuring the spontaneous fission rate of 242Pu. An MCNP 6 neutron transport simulation was used to correct the relative cross section for neutron scattering. The determined results are in good agreement with current experimental and evaluated data sets.

A comparison between orthogonal and parallel plating methods for distal humerus fractures: a prospective randomized trial.

PubMed

Lee, Sang Ki; Kim, Kap Jung; Park, Kyung Hoon; Choy, Won Sik

2014-10-01

With the continuing improvements in implants for distal humerus fractures, it is expected that newer types of plates, which are anatomically precontoured, thinner and less irritating to soft tissue, would have comparable outcomes when used in a clinical study. The purpose of this study was to compare the clinical and radiographic outcomes in patients with distal humerus fractures who were treated with orthogonal and parallel plating methods using precontoured distal humerus plates. Sixty-seven patients with a mean age of 55.4 years (range 22-90 years) were included in this prospective study. The subjects were randomly assigned to receive 1 of 2 treatments: orthogonal or parallel plating. The following results were assessed: operating time, time to fracture union, presence of a step or gap at the articular margin, varus-valgus angulation, functional recovery, and complications. No intergroup differences were observed based on radiological and clinical results between the groups. In our practice, no significant differences were found between the orthogonal and parallel plating methods in terms of clinical outcomes, mean operation time, union time, or complication rates. There were no cases of fracture nonunion in either group; heterotrophic ossification was found 3 patients in orthogonal plating group and 2 patients in parallel plating group. In our practice, no significant differences were found between the orthogonal and parallel plating methods in terms of clinical outcomes or complication rates. However, orthogonal plating method may be preferred in cases of coronal shear fractures, where posterior to anterior fixation may provide additional stability to the intraarticular fractures. Additionally, parallel plating method may be the preferred technique used for fractures that occur at the most distal end of the humerus.

Strip Ionization Chamber as Beam Monitor in the Proton Therapy Eye Treatment

NASA Astrophysics Data System (ADS)

Marchetto, F.; Cirio, R.; Garella, M. A.; Giordanengo, S.; Boriano, A.; Givehchi, N.; La Rosa, A.; Peroni, C.; Donetti, M.; Bourhaleb, F.; Pitta', G.; Cirrone, G. A. P.; Cuttone, G.; Raffaele, L.; Sabini, M. G.; Valastro, L.

2006-04-01

Since spring 2002, ocular pathologies have been treated in Catania at the Centro di AdroTerapia e Applicazioni Nucleari Avanzate (CATANA) within a collaboration between INFN Laboratori Nazionali del Sud (LNS), Physics Department, Ophthalmology Institute, Radiology Institute of the Catania University and CSFNSM Catania. A beam line from a 62 MeV Superconducting Cyclotron is used to treat shallow tumors. The beam is conformed to the tumor shape with a passive delivery system. A detector system has been developed in collaboration with INFN-Torino to be used as real time beam monitor. The detector, placed upstream of the patient collimator, consists of two parallel plate ionization chambers with the anode segmented in strips. Each anode is made of 0.5 mm-wide 256 strips corresponding to (12.8 × 12.8) cm2 sensitive area. With the two strip ionization chambers one can measure the relevant beam parameters during treatment to probe both asymmetry and flatness. In the test carried out at CATANA the detector has been used under different and extreme beam conditions. Preliminary results are given for profiles and skewness, together with a comparison with reference detectors.

New generation of Cherenkov counters

NASA Astrophysics Data System (ADS)

Giomataris, Y.; Charpak, G.; Peskov, V.; Sauli, F.

1992-12-01

Experimental results with a parallel plate avalanche chamber (PPAC) having a CsI photocathode and pad array readout are reported. High gains in excess of 10 5 have been obtained with He gas at atmospheric pressure and traces of CH 4 or CF 4 quencher. Such light gas mixtures extend the transparency for the Cherenkov light to the extreme UV region and allow detector operation with very low sensitivity to the ionization produced by minimum ionizing particles. A hadron blind detector (HBD) is discussed which exploits the broad photon energy bandwidth (≈ 10 eV) and the high Cherenkov threshold ( pπ = 15 GeV). This fast detector, since it has a good spatial resolution, can be used at the future Large Hadron Collider (LHC) or the Superconductivity Super Collider (SSC) either as an efficient electron tagger, rejecting hadrons faking electrons in the calorimeter, or as a pretracker giving fast electron and high-energy muon signature and momentum estimation. Other potential applications in the domain of Cherenkov light detection are also discussed.

Studying Townsend and glow modes in an atmospheric-pressure DBD using mass spectrometry

NASA Astrophysics Data System (ADS)

McKay, Kirsty; Donaghy, David; He, Feng; Bradley, James W.

2018-01-01

Ambient molecular beam mass spectrometry has been employed to examine the effects of the mode of operation and the excitation waveform on the ionic content of a helium-based atmospheric-pressure parallel plate dielectric barrier discharge. By applying 10 kHz microsecond voltage pulses with a nanosecond rise times and 10 kHz sinusoidal voltage waveforms, distinctly different glow and Townsend modes were produced, respectively. Results showed a significant difference in the dominant ion species between the two modes. In the Townsend mode, molecular oxygen ions, atomic oxygen anions and nitric oxide anions are the most abundant species, however, in the glow mode water clusters ions and hydrated nitric oxygen anions dominate. Several hypotheses are put forward to explain these differences, including low electron densities and energies in the Townsend mode, more efficient ionization of water molecules through penning ionization and charge exchange with other species in glow mode, and large temperature gradients due to the pulsed nature of the glow mode, leading to more favorable conditions for cluster formation.

Bactericidal effects of negative air ions on airborne and surface Salmonella enteritidis from an artificially generated aerosol.

PubMed

Seo, K H; Mitchell, B W; Holt, P S; Gast, R K

2001-01-01

The bactericidal effect of high levels of negative ions was studied using a custom-built electrostatic space charge device. To investigate whether the ion-enriched air exerted a bactericidal effect, an aerosol containing Salmonella Enteritidis (SE) was pumped into a sealed plastic chamber. Plates of XLT4 agar were attached to the walls, top, and bottom of the chamber and exposed to the aerosol for 3 h with and without the ionizer treatment. The plates were then removed from the chamber, incubated at 37 degrees C for 24 h, and colonies were counted. An average of greater than 10(3) CFU/plate were observed on plates exposed to the aerosol without the ionizer treatment (control) compared with an average of less than 53 CFU/plate on the ionizer-treated plates. In another series of experiments, the SE aerosol was pumped for 3 h into an empty chamber containing only the ionizer and allowed to collect on the internal surfaces. The inside surfaces of the chamber were then rinsed with 100 ml phosphate-buffered saline that was then plated onto XLT4 plates. While the rinse from the control chamber contained colony counts greater than 400 CFU/ml of wash, no colonies were found in the rinse from the ionizer-treatment chamber. These results indicate that high levels of negative air ions can have a significant impact on the airborne microbial load, and that most of this effect is through direct killing of the organisms. This technology, which also causes significant reduction in airborne dust, has already been successfully applied for poultry hatching cabinets and caged layer rooms. Other potential applications include any enclosed space such as food processing areas, medical institutions, the workplace, and the home, where reduction of airborne and surface pathogens is desired.

Heat exchange apparatus

DOEpatents

Degtiarenko, Pavel V.

2003-08-12

A heat exchange apparatus comprising a coolant conduit or heat sink having attached to its surface a first radial array of spaced-apart parallel plate fins or needles and a second radial array of spaced-apart parallel plate fins or needles thermally coupled to a body to be cooled and meshed with, but not contacting the first radial array of spaced-apart parallel plate fins or needles.

Lanl Neutron-Induced Fission Cross Section Measurement Program

NASA Astrophysics Data System (ADS)

Laptev, A. B.; Tovesson, F.; Hill, T. S.

2014-09-01

A well established program of neutron-induced fission cross section measurement at Los Alamos Neutron Science Center (LANSCE) is supporting the Fuel Cycle Research program (FC R&D). Combining measurements at two LANSCE facilities, the Lujan Center and the Weapons Neutron Research facility (WNR), cover neutron energies over 10 orders of magnitude: from sub-thermal up to 200 MeV. A parallel-plate fission ionization chamber was used as a fission fragment detector. The 235U(n,f) standard was used as the reference. Fission cross sections have been measured for multiple actinides. The new data presented here completes the suite of long-lived Uranium isotopes that were investigated with this experimental approach. The cross section data are presented in comparison with existing evaluations and previous measurements.

Status of Beam Line Detectors for the BigRIPS Fragment Separator at RIKEN RI Beam Factory: Issues on High Rates and Resolution

NASA Astrophysics Data System (ADS)

Sato, Yuki; Fukuda, Naoki; Takeda, Hiroyuki; Kameda, Daisuke; Suzuki, Hiroshi; Shimizu, Yohei; Ahn, DeukSoon; Murai, Daichi; Inabe, Naohito; Shimaoka, Takehiro; Tsubota, Masakatsu; Kaneko, Junichi H.; Chayahara, Akiyoshi; Umezawa, Hitoshi; Shikata, Shinichi; Kumagai, Hidekazu; Murakami, Hiroyuki; Sato, Hiromi; Yoshida, Koichi; Kubo, Toshiyuki

A multiple sampling ionization chamber (MUSIC) and parallel-plate avalanche counters (PPACs) were installed within the superconducting in-flight separator, named BigRIPS, at the RIKEN Nishina Center for particle identification of RI beams. The MUSIC detector showed negligible charge collection inefficiency from recombination of electrons and ions, up to a 99-kcps incidence rate for high-energy heavy ions. For the PPAC detectors, the electrical discharge durability for incident heavy ions was improved by changing the electrode material. Finally, we designed a single crystal diamond detector, which is under development for TOF measurements of high-energy heavy ions, that has a very fast response time (pulse width <1 ns).

Biomechanical comparison of orthogonal versus parallel double plating systems in intraarticular distal humerus fractures.

PubMed

Atalar, Ata C; Tunalı, Onur; Erşen, Ali; Kapıcıoğlu, Mehmet; Sağlam, Yavuz; Demirhan, Mehmet S

2017-01-01

In intraarticular distal humerus fractures, internal fixation with double plates is the gold standard treatment. However the optimal plate configuration is not clear in the literature. The aim of this study was to compare the biomechanical stability of the parallel and the orthogonal anatomical locking plating systems in intraarticular distal humerus fractures in artificial humerus models. Intraarticular distal humerus fracture (AO13-C2) with 5 mm metaphyseal defect was created in sixteen artificial humeral models. Models were fixed with either orthogonal or parallel plating systems with locking screws (Acumed elbow plating systems). Both systems were tested for their stiffness with loads in axial compression, varus, valgus, anterior and posterior bending. Then plastic deformation after cyclic loading in posterior bending and load to failure in posterior bending were tested. The failure mechanisms of all the samples were observed. Stiffness values in every direction were not significantly different among the orthogonal and the parallel plating groups. There was no statistical difference between the two groups in plastic deformation values (0.31 mm-0.29 mm) and load to failure tests in posterior bending (372.4 N-379.7 N). In the orthogonal plating system most of the failures occurred due to the proximal shaft fracture, whereas in the parallel plating system failure occurred due to the shift of the most distal screw in proximal fragment. Our study showed that both plating systems had similar biomechanical stabilities when anatomic plates with distal locking screws were used in intraarticular distal humerus fractures in artificial humerus models. Copyright © 2016 Turkish Association of Orthopaedics and Traumatology. Production and hosting by Elsevier B.V. All rights reserved.

Preliminary results with a strip ionization chamber used as beam monitor for hadrontherapy treatments

NASA Astrophysics Data System (ADS)

Boriano, A.; Bourhaleb, F.; Cirio, R.; Cirrone, G. A. P.; Cuttone, G.; Donetti, M.; Garelli, E.; Giordanengo, S.; Luparia, A.; Marchette, F.; Peroni, C.; Raffaele, L.; Sabini, M. G.; Valastro, L.

2006-01-01

Preliminary results are presented from a test of a parallel plate ionization chamber with the anode segmented in strips (MOPI) to be used as a beam monitor for therapeutical treatments on the 62 MeV proton beam line of the INFN-LNS Superconducting Cyclotron. Ocular pathologies have been treated at the Catana facility since March 2002. The detector, placed downstream of the patient collimator, will allow the measurement of the relevant beam diagnostic parameters during treatment such as integrated beam fluence, for dose determination; the beam baricentre, width and asymmetry will be obtained from the fluence profile sampled with a resolution of about 100 Urn at a rate up to 1 kHz with no dead time. In this test, carried out at LNS, the detector has been exposed to different beam shapes and the integrated fluence derived by the measured beam profiles has been compared with that obtained with other dosimeters normally used for treatment. The skewness of the beam profile has been measured and shown to be suitable to on-line check variations of the beam shape.

Analysis of fatty acids by graphite plate laser desorption/ionization time-of-flight mass spectrometry.

PubMed

Park, K H; Kim, H J

2001-01-01

Fatty acids obtained from triglycerides (trioelin, tripalmitin), foods (milk, corn oil), and phospholipids (phosphotidylcholine, phosphotidylserine, phosphatidic acid) upon alkaline hydrolysis were observed directly without derivatization by graphite plate laser desorption/ionization time-of-flight mass spectrometry (GPLDI-TOFMS). Mass-to-charge ratios predicted for sodium adducts of expected fatty acids (e.g. palmitic, oleic, linoleic and arachidonic acids) were observed without interference. Although at present no quantitation is possible, the graphite plate method enables a simple and rapid qualitative analysis of fatty acids. Copyright 2001 John Wiley & Sons, Ltd.

Formic acid-based direct, on-plate testing of yeast and Corynebacterium species by Bruker Biotyper matrix-assisted laser desorption ionization-time of flight mass spectrometry.

PubMed

Theel, Elitza S; Schmitt, Bryan H; Hall, Leslie; Cunningham, Scott A; Walchak, Robert C; Patel, Robin; Wengenack, Nancy L

2012-09-01

An on-plate testing method using formic acid was evaluated on the Bruker Biotyper matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry system using 90 yeast and 78 Corynebacterium species isolates, and 95.6 and 81.1% of yeast and 96.1 and 92.3% of Corynebacterium isolates were correctly identified to the genus and species levels, respectively. The on-plate method using formic acid yielded identification percentages similar to those for the conventional but more laborious tube-based extraction.

Resistance of a plate in parallel flow at low Reynolds numbers

NASA Technical Reports Server (NTRS)

Janour, Zbynek

1951-01-01

The present paper gives the results of measurements of the resistance of a plate placed parallel to the flow in the range of Reynolds numbers from 10 to 2300; in this range the resistance deviates from the formula of Blasius. The lower limit of validity of the Blasius formula is determined and also the increase in resistance at the edges parallel to the flow in the case of a plate of finite width.

Intercondylar humerus fracture- parallel plating and its results.

PubMed

Kumar, Sanjiv; Singh, Sudhir; Kumar, Dharmender; Kumar, Neeraj; Verma, Reetu

2015-01-01

Intercondylar fracture of humerus is one of the commonest fractures of young adult and counts for about 30% of all elbow fractures. The treatment of these fractures continues to present challenges despite advances in internal fixation. Although orthogonal plating use to provid adequate functional results in these fractures, parallel plating is said to be mechanically more stable construct thus allowing early mobilization and better range of motion. AIM of the study is to assess the clinical as well functional results of these fractures treated with parallel plating. Prospective study in a tertiary care hospital. A total of 23 fresh patients of intercondylar fracture of humerus from Jan 2013 to May 2014 were included in the study and were treated with parallel plating. These patients were followed at 3, 6, 12, 24 weeks and at 1year of follow up and assessed in terms of time for union, range of motion, MAYO score, DASH score and complication rate. At final follow up Mayo score was 96.32±04.96 from 5.00±01.26 and DASH SCORE was 31.42±2.04 which dropped from 150±05.34, Range of motion improved from 21.38±05.70 to 116.1±07.92 with 100% union rate and complications less than 19%. Parallel plating for intercondylar fracture of humerus is excellent method of fixation and results are similar to those treated with orthogonal plating.

Omni-directional railguns

DOEpatents

Shahinpoor, Mohsen

1995-01-01

A device for electromagnetically accelerating projectiles. The invention features two parallel conducting circular plates, a plurality of electrode connections to both upper and lower plates, a support base, and a projectile magazine. A projectile is spring-loaded into a firing position concentrically located between the parallel plates. A voltage source is applied to the plates to cause current to flow in directions defined by selectable, discrete electrode connections on both upper and lower plates. Repulsive Lorentz forces are generated to eject the projectile in a 360 degree range of fire.

[Meta analysis of parallel versus perpendicular double plating for distal humerus fracture of type C in adults].

PubMed

Li, B B; Lin, F; Cai, L H; Chen, Y; Lin, Z J

2017-08-01

Objective: To evaluate the effects of parallel versus perpendicular double plating for distal humerus fracture of type C. Methods: A standardized comprehensive literature search was performed by PubMed, Embase, Cochrane library, CMB, CNKI and Medline datebase.Randomized controlled studies on comparison between parallel versus perpendicular double plating for distal humerus fracture of type C before December 2015 were enrolled in the study.All date were analyzed by the RevMan 5.2 software. Results: Six studies, including 284 patients, met the inclusion criteria.There were 155 patients in perpendicular double plating group, 129 patients in parallel double plating group.The results of Meta-analysis indicated that there were statistically significant difference between the two groups in complications ( OR =2.59, 95% CI : 1.03 to 6.53, P =0.04). There was no significant difference between the two groups in surgical duration ( MD =-1.84, 95% CI : -9.06 to 5.39, P =0.62), bone union time ( MD =0.09, 95% CI : -0.06 to 0.24, P =0.22), Mayo Elbow Performance Score ( MD =0.09, 95% CI : -0.06 to 0.24, P =0.22), Range of Motions ( MD =-0.92, 95% CI : -4.65 to 2.81, P =0.63) and the rate of excellent and good results ( OR =0.64, 95% CI : 0.27 to 1.52, P =0.31). Conclusion: Both perpendicular and parallel double plating are effective in distal humerus fracture of type C, parallel double plating has less complications.

Cooled particle accelerator target

DOEpatents

Degtiarenko, Pavel V.

2005-06-14

A novel particle beam target comprising: a rotating target disc mounted on a retainer and thermally coupled to a first array of spaced-apart parallel plate fins that extend radially inwardly from the retainer and mesh without physical contact with a second array of spaced-apart parallel plate fins that extend radially outwardly from and are thermally coupled to a cooling mechanism capable of removing heat from said second array of spaced-apart fins and located within the first array of spaced-apart parallel fins. Radiant thermal exchange between the two arrays of parallel plate fins provides removal of heat from the rotating disc. A method of cooling the rotating target is also described.

Use of gamma ray radiation to parallel the plates of a Fabry-Perot interferometer

NASA Technical Reports Server (NTRS)

Skinner, Wilbert R.; Hays, Paul B.; Anderson, Sally M.

1987-01-01

The use of gamma radiation to parallel the plates of a Fabry-Perot etalon is examined. The method for determining the etalon parallelism, and the procedure for irradiating the posts are described. Changes in effective gap for the etalon over the surface are utilized to measure the parallelism of the Fabry-Perot etalon. An example in which this technique is applied to an etalon of fused silica plates, which are 132 mm in diameter and coded with zinc sulfide and cryolite, with Zerodur spaces 2 cm in length. The effect of the irradiation of the posts on the thermal performance of the etalon is investigated.

Omni-directional railguns

DOEpatents

Shahinpoor, M.

1995-07-25

A device is disclosed for electromagnetically accelerating projectiles. The invention features two parallel conducting circular plates, a plurality of electrode connections to both upper and lower plates, a support base, and a projectile magazine. A projectile is spring-loaded into a firing position concentrically located between the parallel plates. A voltage source is applied to the plates to cause current to flow in directions defined by selectable, discrete electrode connections on both upper and lower plates. Repulsive Lorentz forces are generated to eject the projectile in a 360 degree range of fire. 4 figs.

Electroless plating of silver nanoparticles on porous silicon for laser desorption/ionization mass spectrometry

NASA Astrophysics Data System (ADS)

Yan, Hong; Xu, Ning; Huang, Wen-Yi; Han, Huan-Mei; Xiao, Shou-Jun

2009-03-01

An improved DIOS (desorption ionization on porous silicon) method for laser desorption/ionization mass spectrometry (LDI MS) by electroless plating of silver nanoparticles (AgNPs) on porous silicon (PSi) was developed. By addition of 4-aminothiophenol (4-ATP) into the AgNO3 plating solution, the plating speed can be slowed down and simultaneously 4-ATP self-assembled monolayers (SAMs) on AgNPs (4-ATP/AgNPs) were formed. Both AgNPs and 4-ATP/AgNPs coated PSi substrates present much higher stability, sensitivity and reproducibility for LDI MS than the un-treated porous silicon ones. Their shelf life in air was tested for several weeks to a month and their mass spectra still displayed the same high quality and sensitivity as the freshly prepared ones. And more 4-ATP SAMs partly play a role of matrix to increase the ionization efficiency. A small organic molecule of tetrapyridinporphyrin (TPyP), oligomers of polyethylene glycol (PEG 400 and 2300), and a peptide of oxytocin were used as examples to demonstrate the feasibility of the silver-plated PSi as a matrix-free-like method for LDI MS. This approach can obtain limits of detection to femtomoles for TPyP, subpicomoles for oxytocin, and picomoles for PEG 400 and 2300, comparable to the traditional matrix method and much better than the DIOS method. It simplifies the sample preparation as a matrix-free-like method without addition of matrix molecules and homogenizes the sample spread over the spot for better and more even mass signals.

CORRIGENDUM: Dielectric dispersion of BaxSr1 - xTiO3 thin film with parallel-plate and coplanar interdigital electrodes Dielectric dispersion of BaxSr1 - xTiO3 thin film with parallel-plate and coplanar interdigital electrodes

NASA Astrophysics Data System (ADS)

Zhang, Xiao-Yu; Song, Qing; Xu, Feng; Sheng, Su; Wang, Peng; Ong, C. K.

2010-03-01

Figures 1, 2 and 5 of this paper are reprinted from the authors' previous paper, Zhang X-Y, Wang P, Sheng S, Xu F and Ong C K 2008 Ferroelectric BaxSr1 - xTiO3 thin-film varactors with parallel plate and interdigital electrodes for microwave applications J. Appl. Phys. 104 124110, copyright 2008, with permission from the American Institute of Physics.

A New Electrospray Aerosol Generator with High Particle Transmission Efficiency

PubMed Central

Fu, Huijing; Patel, Anand C.; Holtzman, Michael J.; Chen, Da-Ren

2012-01-01

A new single-capillary electrospray (ES) aerosol generator has been developed for monodisperse particle production with maximal transmission efficiency. The new generator consists of both a spray chamber in a point-to-orifice-plate configuration and a charge reduction chamber that can hold up to 4 Nuclespot ionizers (Model P-2042, NRD Inc.). The 2 chambers are partitioned by an orifice plate. To optimize the particle transmission efficiency of the prototype, a systematic study was performed on the generator by varying the system setup and operation. Two key dimensions of the generator setup, the orifice diameter and the distance from the capillary tip to the orifice plate, were varied. Fluorescence analysis was applied to characterize the loss of ES-generated particles at different locations of the prototype. It was found that particle loss in the generator could be reduced by either increasing the orifice diameter or decreasing the distance between the capillary tip and the orifice plate. Increasing either the total radioactivity of the ionizers or the flowrate of the particle carrier gas also further decreased the particle loss in the system. The maximum particle transmission efficiency of 88.0% was obtained with the spray chamber fully opened to the charge reduction chamber, the capillary tip at the same level as the orifice plate, and 4 bipolar ionizers installed. PMID:22829715

Unsteady stokes flow of dusty fluid between two parallel plates through porous medium in the presence of magnetic field

NASA Astrophysics Data System (ADS)

Sasikala, R.; Govindarajan, A.; Gayathri, R.

2018-04-01

This paper focus on the result of dust particle between two parallel plates through porous medium in the presence of magnetic field with constant suction in the upper plate and constant injection in the lower plate. The partial differential equations governing the flow are solved by similarity transformation. The velocity of the fluid and the dust particle decreases when there is an increase in the Hartmann number.

Mantle flow through a tear in the Nazca slab inferred from shear wave splitting

NASA Astrophysics Data System (ADS)

Lynner, Colton; Anderson, Megan L.; Portner, Daniel E.; Beck, Susan L.; Gilbert, Hersh

2017-07-01

A tear in the subducting Nazca slab is located between the end of the Pampean flat slab and normally subducting oceanic lithosphere. Tomographic studies suggest mantle material flows through this opening. The best way to probe this hypothesis is through observations of seismic anisotropy, such as shear wave splitting. We examine patterns of shear wave splitting using data from two seismic deployments in Argentina that lay updip of the slab tear. We observe a simple pattern of plate-motion-parallel fast splitting directions, indicative of plate-motion-parallel mantle flow, beneath the majority of the stations. Our observed splitting contrasts previous observations to the north and south of the flat slab region. Since plate-motion-parallel splitting occurs only coincidentally with the slab tear, we propose mantle material flows through the opening resulting in Nazca plate-motion-parallel flow in both the subslab mantle and mantle wedge.

A novel magnet focusing plate for matrix-assisted laser desorption/ionization analysis of magnetic bead-bound analytes.

PubMed

Gode, David; Volmer, Dietrich A

2013-05-15

Magnetic beads are often used for serum profiling of peptide and protein biomarkers. In these assays, the bead-bound analytes are eluted from the beads prior to mass spectrometric analysis. This study describes a novel matrix-assisted laser desorption/ionization (MALDI) technique for direct application and focusing of magnetic beads to MALDI plates by means of dedicated micro-magnets as sample spots. Custom-made MALDI plates with magnetic focusing spots were made using small nickel-coated neodymium micro-magnets integrated into a stainless steel plate in a 16 × 24 (384) pattern. For demonstrating the proof-of-concept, commercial C-18 magnetic beads were used for the extraction of a test compound (reserpine) from aqueous solution. Experiments were conducted to study focusing abilities, the required laser energies, the influence of a matrix compound, dispensing techniques, solvent choice and the amount of magnetic beads. Dispensing the magnetic beads onto the micro-magnet sample spots resulted in immediate and strong binding to the magnetic surface. Light microscope images illustrated the homogeneous distribution of beads across the surfaces of the magnets, when the entire sample volume containing the beads was pipetted onto the surface. Subsequent MALDI analysis of the bead-bound analyte demonstrated excellent and reproducible ionization yields. The surface-assisted laser desorption/ionization (SALDI) properties of the strongly light-absorbing γ-Fe2O3-based beads resulted in similar ionization efficiencies to those obtained from experiments with an additional MALDI matrix compound. This feasibility study successfully demonstrated the magnetic focusing abilities for magnetic bead-bound analytes on a novel MALDI plate containing small micro-magnets as sample spots. One of the key advantages of this integrated approach is that no elution steps from magnetic beads were required during analyses compared with conventional bead experiments. Copyright © 2013 John Wiley & Sons, Ltd.

NUCLEAR REACTOR FUEL ELEMENT

DOEpatents

Wheelock, C.W.; Baumeister, E.B.

1961-09-01

A reactor fuel element utilizing fissionable fuel materials in plate form is described. This fuel element consists of bundles of fuel-bearing plates. The bundles are stacked inside of a tube which forms the shell of the fuel element. The plates each have longitudinal fins running parallel to the direction of coolant flow, and interspersed among and parallel to the fins are ribs which position the plates relative to each other and to the fuel element shell. The plate bundles are held together by thin bands or wires. The ex tended surface increases the heat transfer capabilities of a fuel element by a factor of 3 or more over those of a simple flat plate.

A study on the suitability of the PTW microDiamond detector for kilovoltage x-ray beam dosimetry.

PubMed

Damodar, Joshita; Odgers, David; Pope, Dane; Hill, Robin

2018-05-01

Kilovoltage x-ray beams are widely used in treating skin cancers and in biological irradiators. In this work, we have evaluated four dosimeters (ionization chambers and solid state detectors) in their suitability for relative dosimetry of kilovoltage x-ray beams in the energy range of 50 - 280kVp. The solid state detectors, which have not been investigated with low energy x-rays, were the PTW 60019 microDiamond synthetic diamond detector and the PTW 60012 diode. The two ionization chambers used were the PTW Advanced Markus parallel plate chamber and the PTW PinPoint small volume chamber. For each of the dosimeters, percentage depth doses were measured in water over the full range of x-ray beams and for field sizes ranging from 2cm diameter to 12 × 12cm. In addition, depth doses were measured for a narrow aperture (7mm diameter) using the PTW microDiamond detector. For comparison, the measured data was compared with Monte Carlo calculated doses using the EGSnrc Monte Carlo package. The depth dose results indicate that the Advanced Markus parallel plate and PinPoint ionization chambers were suitable for depth dose measurements in the beam quality range with an uncertainty of less than 3%, including in the regions closer to the surface of the water as compared with Monte Carlo depth dose data for all six energy beams. The response of the PTW Diode E detector was accurate to within 4% for all field sizes in the energy range of 50-125kVp but showed larger variations for higher energies of up to 12% with the 12 × 12cm field size. In comparison, the microDiamond detector had good agreement over all energies for both smaller and larger field sizes generally within 1% as compared to the Advanced Markus chamber field and Monte Carlo calculations. The only exceptions were in measuring the dose at the surface of the water phantom where larger differences were found. For the 7mm diameter field, the agreement between the microDiamond detector and Monte Carlo calculations was good being better than 1% except at the surface. Based on these results, the PTW microDiamond detector has shown to be a suitable detector for relative dosimetry of low energy x-ray beams over a wide range of x-ray beam energies. Copyright © 2018 Elsevier Ltd. All rights reserved.

Alkali ionization detector

DOEpatents

Hrizo, John; Bauerle, James E.; Witkowski, Robert E.

1982-01-01

A calibration filament containing a sodium-bearing compound is included in combination with the sensing filament and ion collector plate of a sodium ionization detector to permit periodic generation of sodium atoms for the in-situ calibration of the detector.

MULTI-PLATE IONIZATION CHAMBER FOR THE DETECTION OF SLOW NEUTRONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bubzanowski, A.; Grotowski, K.

1957-01-01

A description is given of an ionization chamber, the electrodes of which are coated with a layer of natural boron of thickness 3 mg/cm/sup 2/. Each electrode of the chamber consists of three disks, placed between plates of the other electrodes. The capacitance between the electrodes does not exceed 15 micromicrofarads. The technology of coating the layer is as follows: the boron is mixed with alcohol and a small amount of Canada balsam and is coated in the form of an emulsion on the plates. The chamber efficiency is approximately 2%. The filler is argon at atmospheric pressure. The durationmore » of the output pulses after forming is approximately 5 microseconds.« less

PLATES WITH OXIDE INSERTS

DOEpatents

West, J.M.; Schumar, J.F.

1958-06-10

Planar-type fuel assemblies for nuclear reactors are described, particularly those comprising fuel in the oxide form such as thoria and urania. The fuel assembly consists of a plurality of parallel spaced fuel plate mennbers having their longitudinal side edges attached to two parallel supporting side plates, thereby providing coolant flow channels between the opposite faces of adjacent fuel plates. The fuel plates are comprised of a plurality of longitudinally extending tubular sections connected by web portions, the tubular sections being filled with a plurality of pellets of the fuel material and the pellets being thermally bonded to the inside of the tubular section by lead.

Target Plate Material Influence on Fullerene-C60 Laser Desorption/Ionization Efficiency

NASA Astrophysics Data System (ADS)

Zeegers, Guido P.; Günthardt, Barbara F.; Zenobi, Renato

2016-04-01

Systematic laser desorption/ionization (LDI) experiments of fullerene-C60 on a wide range of target plate materials were conducted to gain insight into the initial ion formation in matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. The positive and negative ion signal intensities of precursor, fragment, and cluster ions were monitored, varying both the laser fluence (0-3.53 Jcm-2) and the ion extraction delay time (0-950 ns). The resulting species-specific ion signal intensities are an indication for the ionization mechanisms that contribute to LDI and the time frames in which they operate, providing insight in the (MA)LDI primary ionization. An increasing electrical resistivity of the target plate material increases the fullerene-C60 precursor and fragment anion signal intensity. Inconel 625 and Ti90/Al6/V4, both highly electrically resistive, provide the highest anion signal intensities, exceeding the cation signal intensity by a factor ~1.4 for the latter. We present a mechanism based on transient electrical field strength reduction to explain this trend. Fullerene-C60 cluster anion formation is negligible, which could be due to the high extraction potential. Cluster cations, however, are readily formed, although for high laser fluences, the preferred channel is formation of precursor and fragment cations. Ion signal intensity depends greatly on the choice of substrate material, and careful substrate selection could, therefore, allow for more sensitive (MA)LDI measurements.

Molecular Ionization-Desorption Analysis Source (MIDAS) for Mass Spectrometry: Thin-Layer Chromatography.

PubMed

Winter, Gregory T; Wilhide, Joshua A; LaCourse, William R

2016-02-01

Molecular ionization-desorption analysis source (MIDAS), which is a desorption atmospheric pressure chemical ionization (DAPCI) type source, for mass spectrometry has been developed as a multi-functional platform for the direct sampling of surfaces. In this article, its utility for the analysis of thin-layer chromatography (TLC) plates is highlighted. Amino acids, which are difficult to visualize without staining reagents or charring, were detected and identified directly from a TLC plate. To demonstrate the full potential of MIDAS, all active ingredients from an analgesic tablet, separated on a TLC plate, were successfully detected using both positive and negative ion modes. The identity of each of the compounds was confirmed from their mass spectra and compared against standards. Post separation, the chemical signal (blue permanent marker) as reference marks placed at the origin and solvent front were used to calculate retention factor (Rf) values from the resulting ion chromatogram. The quantitative capabilities of the device were exhibited by scanning caffeine spots on a TLC plate of increasing sample amount. A linear curve based on peak are, R2 = 0.994, was generated for seven spots ranging from 50 to 1000 ng of caffeine per spot.

Molecular Ionization-Desorption Analysis Source (MIDAS) for Mass Spectrometry: Thin-Layer Chromatography

NASA Astrophysics Data System (ADS)

Winter, Gregory T.; Wilhide, Joshua A.; LaCourse, William R.

2016-02-01

Molecular ionization-desorption analysis source (MIDAS), which is a desorption atmospheric pressure chemical ionization (DAPCI) type source, for mass spectrometry has been developed as a multi-functional platform for the direct sampling of surfaces. In this article, its utility for the analysis of thin-layer chromatography (TLC) plates is highlighted. Amino acids, which are difficult to visualize without staining reagents or charring, were detected and identified directly from a TLC plate. To demonstrate the full potential of MIDAS, all active ingredients from an analgesic tablet, separated on a TLC plate, were successfully detected using both positive and negative ion modes. The identity of each of the compounds was confirmed from their mass spectra and compared against standards. Post separation, the chemical signal (blue permanent marker) as reference marks placed at the origin and solvent front were used to calculate retention factor (Rf) values from the resulting ion chromatogram. The quantitative capabilities of the device were exhibited by scanning caffeine spots on a TLC plate of increasing sample amount. A linear curve based on peak are, R2 = 0.994, was generated for seven spots ranging from 50 to 1000 ng of caffeine per spot.

Parallel-plate heat pipe apparatus having a shaped wick structure

DOEpatents

Rightley, Michael J.; Adkins, Douglas R.; Mulhall, James J.; Robino, Charles V.; Reece, Mark; Smith, Paul M.; Tigges, Chris P.

2004-12-07

A parallel-plate heat pipe is disclosed that utilizes a plurality of evaporator regions at locations where heat sources (e.g. semiconductor chips) are to be provided. A plurality of curvilinear capillary grooves are formed on one or both major inner surfaces of the heat pipe to provide an independent flow of a liquid working fluid to the evaporator regions to optimize heat removal from different-size heat sources and to mitigate the possibility of heat-source shadowing. The parallel-plate heat pipe has applications for heat removal from high-density microelectronics and laptop computers.

Efficiency of plasma actuator ionization in shock wave modification in a rarefied supersonic flow over a flat plate

NASA Astrophysics Data System (ADS)

Joussot, Romain; Lago, Viviana; Parisse, Jean-Denis

2014-12-01

This paper describes experimental and numerical investigations focused on the shock wave modification, induced by a dc glow discharge, of a Mach 2 flow under rarefied regime. The model under investigation is a flat plate equipped with a plasma actuator composed of two electrodes. The glow discharge is generated by applying a negative potential to the upstream electrode, enabling the creation of a weakly ionized plasma. The natural flow (i.e. without the plasma) exhibits a thick laminar boundary layer and a shock wave with a hyperbolic shape. Images of the flow obtained with an ICCD camera revealed that the plasma discharge induces an increase in the shock wave angle. Thermal effects (volumetric, and at the surface) and plasma effects (ionization, and thermal non-equilibrium) are the most relevant processes explaining the observed modifications. The effect induced by the heating of the flat plate surface is studied experimentally by replacing the upstream electrode by a heating element, and numerically by modifying the thermal boundary condition of the model surface. The results show that for a similar temperature distribution over the plate surface, modifications induced by the heating element are lower than those produced by the plasma. This difference shows that other effects than purely thermal effects are involved with the plasma actuator. Measurements of the electron density with a Langmuir probe highlight the fact that the ionization degree plays an important role into the modification of the flow. The gas properties, especially the isentropic exponent, are indeed modified by the plasma above the actuator and upstream the flat plate. This leads to a local modification of the flow conditions, inducing an increase in the shock wave angle.

Focusing, refraction, and asymmetric transmission of elastic waves in solid metamaterials with aligned parallel gaps.

PubMed

Su, Xiaoshi; Norris, Andrew N

2016-06-01

Gradient index (GRIN), refractive, and asymmetric transmission devices for elastic waves are designed using a solid with aligned parallel gaps. The gaps are assumed to be thin so that they can be considered as parallel cracks separating elastic plate waveguides. The plates do not interact with one another directly, only at their ends where they connect to the exterior solid. To formulate the transmission and reflection coefficients for SV- and P-waves, an analytical model is established using thin plate theory that couples the waveguide modes with the waves in the exterior body. The GRIN lens is designed by varying the thickness of the plates to achieve different flexural wave speeds. The refractive effect of SV-waves is achieved by designing the slope of the edge of the plate array, and keeping the ratio between plate length and flexural wavelength fixed. The asymmetric transmission of P-waves is achieved by sending an incident P-wave at a critical angle, at which total conversion to SV-wave occurs. An array of parallel gaps perpendicular to the propagation direction of the reflected waves stop the SV-wave but let P-waves travel through. Examples of focusing, steering, and asymmetric transmission devices are discussed.

Dual parallel mass spectrometry for lipid and vitamin D analysis

USDA-ARS?s Scientific Manuscript database

There are numerous options for mass spectrometric analysis of lipids, including different types of ionization, and a wide variety of experiments using different scan modes that can be conducted. Atmospheric pressure chemical ionization (APCI) and electrospray ionization (ESI) provide complementary ...

Analysis of small biomolecules and xenobiotic metabolism using converted graphene-like monolayer plates and laser desorption/ionization time-of-flight mass spectrometry.

PubMed

Kang, Hyunook; Yun, Hoyeol; Lee, Sang Wook; Yeo, Woon-Seok

2017-06-01

We report a method of small molecule analysis using a converted graphene-like monolayer (CGM) plate and laser desorption/ionization time-of-flight mass spectrometry (LDI-TOF MS) without organic matrices. The CGM plate was prepared from self-assembled monolayers of biphenyl-4-thiol on gold using electron beam irradiation followed by an annealing step. The above plate was utilized for the LDI-TOF MS analyses of various small molecules and their mixtures, e.g., amino acids, sugars, fatty acids, oligoethylene glycols, and flavonoids. The CGM plate afforded high signal-to-noise ratios, good limits of detection (1pmol to 10fmol), and reusability for up to 30 cycles. As a practical application, the enzymatic activity of the cytochrome P450 2A6 (CYP2A6) enzyme in human liver microsomes was assessed in the 7-hydroxylation of coumarin using the CGM plate without other purification steps. We believe that the prepared CGM plate can be practically used with the advantages of simplicity, sensitivity, and reusability for the matrix-free analysis of small biomolecules. Copyright © 2017 Elsevier B.V. All rights reserved.

New sample cell configuration for wide-frequency dielectric spectroscopy: DC to radio frequencies.

PubMed

Nakanishi, Masahiro; Sasaki, Yasutaka; Nozaki, Ryusuke

2010-12-01

A new configuration for the sample cell to be used in broadband dielectric spectroscopy is presented. A coaxial structure with a parallel plate capacitor (outward parallel plate cell: OPPC) has made it possible to extend the frequency range significantly in comparison with the frequency range of the conventional configuration. In the proposed configuration, stray inductance is significantly decreased; consequently, the upper bound of the frequency range is improved by two orders of magnitude from the upper limit of conventional parallel plate capacitor (1 MHz). Furthermore, the value of capacitance is kept high by using a parallel plate configuration. Therefore, the precision of the capacitance measurement in the lower frequency range remains sufficiently high. Finally, OPPC can cover a wide frequency range (100 Hz-1 GHz) with an appropriate admittance measuring apparatus such as an impedance or network analyzer. The OPPC and the conventional dielectric cell are compared by examining the frequency dependence of the complex permittivity for several polar liquids and polymeric films.

True Shear Parallel Plate Viscometer

NASA Technical Reports Server (NTRS)

Ethridge, Edwin; Kaukler, William

2010-01-01

This viscometer (which can also be used as a rheometer) is designed for use with liquids over a large temperature range. The device consists of horizontally disposed, similarly sized, parallel plates with a precisely known gap. The lower plate is driven laterally with a motor to apply shear to the liquid in the gap. The upper plate is freely suspended from a double-arm pendulum with a sufficiently long radius to reduce height variations during the swing to negligible levels. A sensitive load cell measures the shear force applied by the liquid to the upper plate. Viscosity is measured by taking the ratio of shear stress to shear rate.

On plate graphite supported sample processing for simultaneous lipid and protein identification by matrix assisted laser desorption ionization mass spectrometry.

PubMed

Calvano, Cosima Damiana; van der Werf, Inez Dorothé; Sabbatini, Luigia; Palmisano, Francesco

2015-05-01

The simultaneous identification of lipids and proteins by matrix assisted laser desorption ionization-mass spectrometry (MALDI-MS) after direct on-plate processing of micro-samples supported on colloidal graphite is demonstrated. Taking advantages of large surface area and thermal conductivity, graphite provided an ideal substrate for on-plate proteolysis and lipid extraction. Indeed proteins could be efficiently digested on-plate within 15 min, providing sequence coverages comparable to those obtained by conventional in-solution overnight digestion. Interestingly, detection of hydrophilic phosphorylated peptides could be easily achieved without any further enrichment step. Furthermore, lipids could be simultaneously extracted/identified without any additional treatment/processing step as demonstrated for model complex samples such as milk and egg. The present approach is simple, efficient, of large applicability and offers great promise for protein and lipid identification in very small samples. Copyright © 2015 Elsevier B.V. All rights reserved.

The effect of surface charge, negative and bipolar ionization on the deposition of airborne bacteria.

PubMed

Meschke, S; Smith, B D; Yost, M; Miksch, R R; Gefter, P; Gehlke, S; Halpin, H A

2009-04-01

A series of experiments were conducted to evaluate the effect of surface charge and air ionization on the deposition of airborne bacteria. The interaction between surface electrostatic potential and the deposition of airborne bacteria in an indoor environment was investigated using settle plates charged with electric potentials of 0, +/-2.5kV and +/-5kV. Results showed that bacterial deposition on the plates increased proportionally with increased potential to over twice the gravitational sedimentation rate at +5kV. Experiments were repeated under similar conditions in the presence of either negative or bipolar air ionization. Bipolar air ionization resulted in reduction of bacterial deposition onto the charged surfaces to levels nearly equal to gravitational sedimentation. In contrast, diffusion charging appears to have occurred during negative air ionization, resulting in an even greater deposition onto the oppositely charged surface than observed without ionization. Static charges on fomitic surfaces may attract bacteria resulting in deposition in excess of that expected by gravitational sedimentation or simple diffusion. Implementation of bipolar ionization may result in reduction of bacterial deposition. Fomitic surfaces are important vehicles for the transmission of infectious organisms. This study has demonstrated a simple strategy for minimizing charge related deposition of bacteria on surfaces.

Advanced PIC-MCC simulation for the investigation of step-ionization effect in intermediate-pressure capacitively coupled plasmas

NASA Astrophysics Data System (ADS)

Kim, Jin Seok; Hur, Min Young; Kim, Chang Ho; Kim, Ho Jun; Lee, Hae June

2018-03-01

A two-dimensional parallelized particle-in-cell simulation has been developed to simulate a capacitively coupled plasma reactor. The parallelization using graphics processing units is applied to resolve the heavy computational load. It is found that the step-ionization plays an important role in the intermediate gas pressure of a few Torr. Without the step-ionization, the average electron density decreases while the effective electron temperature increases with the increase of gas pressure at a fixed power. With the step-ionization, however, the average electron density increases while the effective electron temperature decreases with the increase of gas pressure. The cases with the step-ionization agree well with the tendency of experimental measurement. The electron energy distribution functions show that the population of electrons having intermediate energy from 4.2 to 12 eV is relaxed by the step-ionization. Also, it was observed that the power consumption by the electrons is increasing with the increase of gas pressure by the step-ionization process, while the power consumption by the ions decreases with the increase of gas pressure.

Rough Electrode Creates Excess Capacitance in Thin-Film Capacitors

PubMed Central

2017-01-01

The parallel-plate capacitor equation is widely used in contemporary material research for nanoscale applications and nanoelectronics. To apply this equation, flat and smooth electrodes are assumed for a capacitor. This essential assumption is often violated for thin-film capacitors because the formation of nanoscale roughness at the electrode interface is very probable for thin films grown via common deposition methods. In this work, we experimentally and theoretically show that the electrical capacitance of thin-film capacitors with realistic interface roughness is significantly larger than the value predicted by the parallel-plate capacitor equation. The degree of the deviation depends on the strength of the roughness, which is described by three roughness parameters for a self-affine fractal surface. By applying an extended parallel-plate capacitor equation that includes the roughness parameters of the electrode, we are able to calculate the excess capacitance of the electrode with weak roughness. Moreover, we introduce the roughness parameter limits for which the simple parallel-plate capacitor equation is sufficiently accurate for capacitors with one rough electrode. Our results imply that the interface roughness beyond the proposed limits cannot be dismissed unless the independence of the capacitance from the interface roughness is experimentally demonstrated. The practical protocols suggested in our work for the reliable use of the parallel-plate capacitor equation can be applied as general guidelines in various fields of interest. PMID:28745040

Rough Electrode Creates Excess Capacitance in Thin-Film Capacitors.

PubMed

Torabi, Solmaz; Cherry, Megan; Duijnstee, Elisabeth A; Le Corre, Vincent M; Qiu, Li; Hummelen, Jan C; Palasantzas, George; Koster, L Jan Anton

2017-08-16

The parallel-plate capacitor equation is widely used in contemporary material research for nanoscale applications and nanoelectronics. To apply this equation, flat and smooth electrodes are assumed for a capacitor. This essential assumption is often violated for thin-film capacitors because the formation of nanoscale roughness at the electrode interface is very probable for thin films grown via common deposition methods. In this work, we experimentally and theoretically show that the electrical capacitance of thin-film capacitors with realistic interface roughness is significantly larger than the value predicted by the parallel-plate capacitor equation. The degree of the deviation depends on the strength of the roughness, which is described by three roughness parameters for a self-affine fractal surface. By applying an extended parallel-plate capacitor equation that includes the roughness parameters of the electrode, we are able to calculate the excess capacitance of the electrode with weak roughness. Moreover, we introduce the roughness parameter limits for which the simple parallel-plate capacitor equation is sufficiently accurate for capacitors with one rough electrode. Our results imply that the interface roughness beyond the proposed limits cannot be dismissed unless the independence of the capacitance from the interface roughness is experimentally demonstrated. The practical protocols suggested in our work for the reliable use of the parallel-plate capacitor equation can be applied as general guidelines in various fields of interest.

Heat exchange assembly

DOEpatents

Lowenstein, Andrew; Sibilia, Marc; Miller, Jeffrey; Tonon, Thomas S.

2004-06-08

A heat exchange assembly comprises a plurality of plates disposed in a spaced-apart arrangement, each of the plurality of plates includes a plurality of passages extending internally from a first end to a second end for directing flow of a heat transfer fluid in a first plane, a plurality of first end-piece members equaling the number of plates and a plurality of second end-piece members also equaling the number of plates, each of the first and second end-piece members including a recessed region adapted to fluidly connect and couple with the first and second ends of the plate, respectively, and further adapted to be affixed to respective adjacent first and second end-piece members in a stacked formation, and each of the first and second end-piece members further including at least one cavity for enabling entry of the heat transfer fluid into the plate, exit of the heat transfer fluid from the plate, or 180.degree. turning of the fluid within the plate to create a serpentine-like fluid flow path between points of entry and exit of the fluid, and at least two fluid conduits extending through the stacked plurality of first and second end-piece members for providing first fluid connections between the parallel fluid entry points of adjacent plates and a fluid supply inlet, and second fluid connections between the parallel fluid exit points of adjacent plates and a fluid discharge outlet so that the heat transfer fluid travels in parallel paths through each respective plate.

Hear Exchange Assembly

DOEpatents

Lowenstein, Andrew; Sibilia, Marc; Miller, Jeffrey; Tonon, Thomas S.

2003-05-27

A heat exchange assembly comprises a plurality of plates disposed in a spaced-apart arrangement, each of the plurality of plates includes a plurality of passages extending internally from a first end to a second end for directing flow of a heat transfer fluid in a first plane, a plurality of first end-piece members equaling the number of plates and a plurality of second end-piece members also equaling the number of plates, each of the first and second end-piece members including a recessed region adapted to fluidly connect and couple with the first and second ends of the plate, respectively, and further adapted to be affixed to respective adjacent first and second end-piece members in a stacked formation, and each of the first and second end-piece members further including at least one cavity for enabling entry of the heat transfer fluid into the plate, exit of the heat transfer fluid from the plate, or 180.degree. turning of the fluid within the plate to create a serpentine-like fluid flow path between points of entry and exit of the fluid, and at least two fluid conduits extending through the stacked plurality of first and second end-piece members for providing first fluid connections between the parallel fluid entry points of adjacent plates and a fluid supply inlet, and second fluid connections between the parallel fluid exit points of adjacent plates and a fluid discharge outlet so that the heat transfer fluid travels in parallel paths through each respective plate.

Multiple parallel mass spectrometry for lipid and vitamin D analysis

USDA-ARS?s Scientific Manuscript database

Liquid chromatography (LC) coupled to mass spectrometry (MS) has become the method of choice for analysis of complex lipid samples. Two types of ionization sources have emerged as the most commonly used to couple LC to MS: atmospheric pressure chemical ionization (APCI) and electrospray ionization ...

Trench-parallel flow beneath the nazca plate from seismic anisotropy.

PubMed

Russo, R M; Silver, P G

1994-02-25

Shear-wave splitting of S and SKS phases reveals the anisotropy and strain field of the mantle beneath the subducting Nazca plate, Cocos plate, and the Caribbean region. These observations can be used to test models of mantle flow. Two-dimensional entrained mantle flow beneath the subducting Nazca slab is not consistent with the data. Rather, there is evidence for horizontal trench-parallel flow in the mantle beneath the Nazca plate along much of the Andean subduction zone. Trench-parallel flow is attributale utable to retrograde motion of the slab, the decoupling of the slab and underlying mantle, and a partial barrier to flow at depth, resulting in lateral mantle flow beneath the slab. Such flow facilitates the transfer of material from the shrinking mantle reservoir beneath the Pacific basin to the growing mantle reservoir beneath the Atlantic basin. Trenchparallel flow may explain the eastward motions of the Caribbean and Scotia sea plates, the anomalously shallow bathymetry of the eastern Nazca plate, the long-wavelength geoid high over western South America, and it may contribute to the high elevation and intense deformation of the central Andes.

Target Plate Material Influence on Fullerene-C60 Laser Desorption/Ionization Efficiency.

PubMed

Zeegers, Guido P; Günthardt, Barbara F; Zenobi, Renato

2016-04-01

Systematic laser desorption/ionization (LDI) experiments of fullerene-C60 on a wide range of target plate materials were conducted to gain insight into the initial ion formation in matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. The positive and negative ion signal intensities of precursor, fragment, and cluster ions were monitored, varying both the laser fluence (0-3.53 Jcm(-2)) and the ion extraction delay time (0-950 ns). The resulting species-specific ion signal intensities are an indication for the ionization mechanisms that contribute to LDI and the time frames in which they operate, providing insight in the (MA)LDI primary ionization. An increasing electrical resistivity of the target plate material increases the fullerene-C60 precursor and fragment anion signal intensity. Inconel 625 and Ti90/Al6/V4, both highly electrically resistive, provide the highest anion signal intensities, exceeding the cation signal intensity by a factor ~1.4 for the latter. We present a mechanism based on transient electrical field strength reduction to explain this trend. Fullerene-C60 cluster anion formation is negligible, which could be due to the high extraction potential. Cluster cations, however, are readily formed, although for high laser fluences, the preferred channel is formation of precursor and fragment cations. Ion signal intensity depends greatly on the choice of substrate material, and careful substrate selection could, therefore, allow for more sensitive (MA)LDI measurements. Graphical Abstract ᅟ.

Parallel production and verification of protein products using a novel high-throughput screening method.

PubMed

Tegel, Hanna; Yderland, Louise; Boström, Tove; Eriksson, Cecilia; Ukkonen, Kaisa; Vasala, Antti; Neubauer, Peter; Ottosson, Jenny; Hober, Sophia

2011-08-01

Protein production and analysis in a parallel fashion is today applied in laboratories worldwide and there is a great need to improve the techniques and systems used for this purpose. In order to save time and money, a fast and reliable screening method for analysis of protein production and also verification of the protein product is desired. Here, a micro-scale protocol for the parallel production and screening of 96 proteins in plate format is described. Protein capture was achieved using immobilized metal affinity chromatography and the product was verified using matrix-assisted laser desorption ionization time-of-flight MS. In order to obtain sufficiently high cell densities and product yield in the small-volume cultivations, the EnBase® cultivation technology was applied, which enables cultivation in as small volumes as 150 μL. Here, the efficiency of the method is demonstrated by producing 96 human, recombinant proteins, both in micro-scale and using a standard full-scale protocol and comparing the results in regard to both protein identity and sample purity. The results obtained are highly comparable to those acquired through employing standard full-scale purification protocols, thus validating this method as a successful initial screening step before protein production at a larger scale. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hall effects on unsteady MHD reactive flow of second grade fluid through porous medium in a rotating parallel plate channel

NASA Astrophysics Data System (ADS)

Krishna, M. Veera; Swarnalathamma, B. V.

2017-07-01

We considered the transient MHD flow of a reactive second grade fluid through porous medium between two infinitely long horizontal parallel plates when one of the plate is set into uniform accelerated motion in the presence of a uniform transverse magnetic field under Arrhenius reaction rate. The governing equations are solved by Laplace transform technique. The effects of the pertinent parameters on the velocity, temperature are discussed in detail. The shear stress and Nusselt number at the plates are also obtained analytically and computationally discussed with reference to governing parameters.

Inhibiting the TE1-mode diffraction losses in terahertz parallel-plate waveguides using concave plates.

PubMed

Mbonye, Marx; Mendis, Rajind; Mittleman, Daniel M

2012-12-03

We present numerical and experimental results on inhibiting diffraction losses associated with the lowest order transverse electric (TE1) mode of a terahertz (THz) parallel-plate waveguide (PPWG) via the use of slightly concave plates. We find that there is an optimal radius of curvature that inhibits the diffraction for a given waveguide operating at a given frequency. We also find that introducing this curvature does not introduce any additional group-velocity dispersion. These results support the possibility of realizing long range transport of THz radiation using the TE1 mode of the PPWG.

A clamped rectangular plate containing a crack

NASA Technical Reports Server (NTRS)

Tang, R.; Erdogan, F.

1985-01-01

The general problem of a rectangular plate clamped along two parallel sides and containing a crack parallel to the clamps is considered. The problem is formulated in terms of a system of singular integral equations and the asymptotic behavior of the stress state near the corners is investigated. Numerical examples are considered for a clamped plate without a crack and with a centrally located crack, and the stress intensity factors and the stresses along the clamps are calculated.

A comparison of parallel and diverging screw angles in the stability of locked plate constructs.

PubMed

Wähnert, D; Windolf, M; Brianza, S; Rothstock, S; Radtke, R; Brighenti, V; Schwieger, K

2011-09-01

We investigated the static and cyclical strength of parallel and angulated locking plate screws using rigid polyurethane foam (0.32 g/cm(3)) and bovine cancellous bone blocks. Custom-made stainless steel plates with two conically threaded screw holes with different angulations (parallel, 10° and 20° divergent) and 5 mm self-tapping locking screws underwent pull-out and cyclical pull and bending tests. The bovine cancellous blocks were only subjected to static pull-out testing. We also performed finite element analysis for the static pull-out test of the parallel and 20° configurations. In both the foam model and the bovine cancellous bone we found the significantly highest pull-out force for the parallel constructs. In the finite element analysis there was a 47% more damage in the 20° divergent constructs than in the parallel configuration. Under cyclical loading, the mean number of cycles to failure was significantly higher for the parallel group, followed by the 10° and 20° divergent configurations. In our laboratory setting we clearly showed the biomechanical disadvantage of a diverging locking screw angle under static and cyclical loading.

Survey of ion plating sources. [conferences

NASA Technical Reports Server (NTRS)

Spalvins, T.

1979-01-01

Based on the type of evaporation source, gaseous media and mode of transport, the following is discussed: resistance, electron beam, sputtering, reactive and ion beam evaporation. Ionization efficiencies and ion energies in the glow discharge determine the percentage of atoms which are ionized under typical ion plating conditions. The plating flux consists of a small number of energetic ions and a large number of energetic neutrals. The energy distribution ranges from thermal energies up to a maximum energy of the discharge. The various reaction mechanisms which contribute to the exceptionally strong adherence - formation of a graded sustrate/coating interface are not fully understood, however the controlling factors are evaluated. The influence of process variables on the nucleation and growth characteristics are illustrated in terms of morphological changes which affect the mechanical and tribological properties of the coating.

Dustbuster: a New Generation Impact-ionization Time-of-flight Mass Spectrometer for in situ Analysis of Cosmic Dust

NASA Astrophysics Data System (ADS)

Austin, D. E.; Ahrens, T. J.; Beauchamp, J. L.

2000-10-01

We have developed and tested a small impact-ionization time-of-flight mass spectrometer for analysis of cosmic dust, suitable for use on deep space missions. This mass spectrometer, named Dustbuster, incorporates a large target area and a reflectron, simultaneously optimizing mass resolution, sensitivity, and collection efficiency. Dust particles hitting the 65-cm2 target plate are partially ionized. The resulting ions are accelerated through a modified reflectron that focuses the ions in space and time to produce high-resolution spectra. The instrument, shown below, measures 10 x 10 x 20 cm, has a mass of 500 g, and consumes little power. Laser desorption ionization of metal and mineral samples (embedded in the impact plate) simulates particle impacts for instrument performance tests. Mass resolution in these experiments is near 200, permitting resolution of isotopes. The mass spectrometer can be combined with other instrument components to determine dust particle trajectories and sizes. This project was funded by NASA's Planetary Instrument Definition and Development Program.

Theoretical and Experimental Study of the Primary Current Distribution in Parallel-Plate Electrochemical Reactors

ERIC Educational Resources Information Center

Vazquez Aranda, Armando I.; Henquin, Eduardo R.; Torres, Israel Rodriguez; Bisang, Jose M.

2012-01-01

A laboratory experiment is described to determine the primary current distribution in parallel-plate electrochemical reactors. The electrolyte is simulated by conductive paper and the electrodes are segmented to measure the current distribution. Experiments are reported with the electrolyte confined to the interelectrode gap, where the current…

Survey of ion plating sources

NASA Technical Reports Server (NTRS)

Spalvins, T.

1979-01-01

Ion plating is a plasma deposition technique where ions of the gas and the evaporant have a decisive role in the formation of a coating in terms of adherence, coherence, and morphological growth. The range of materials that can be ion plated is predominantly determined by the selection of the evaporation source. Based on the type of evaporation source, gaseous media and mode of transport, the following will be discussed: resistance, electron beam sputtering, reactive and ion beam evaporation. Ionization efficiencies and ion energies in the glow discharge determine the percentage of atoms which are ionized under typical ion plating conditions. The plating flux consists of a small number of energetic ions and a large number of energetic neutrals. The energy distribution ranges from thermal energies up to a maximum energy of the discharge. The various reaction mechanisms which contribute to the exceptionally strong adherence - formation of a graded substrate/coating interface are not fully understood, however the controlling factors are evaluated. The influence of process variables on the nucleation and growth characteristics are illustrated in terms of morphological changes which affect the mechanical and tribological properties of the coating.

Breakdown assisted by a novel electron drift injection in the J-TEXT tokamak

NASA Astrophysics Data System (ADS)

Wang, Nengchao; Jin, Hai; Zhuang, Ge; Ding, Yonghua; Pan, Yuan; Cen, Yishun; Chen, Zhipeng; Huang, Hai; Liu, Dequan; Rao, Bo; Zhang, Ming; Zou, Bichen

2014-07-01

A novel electron drift injection (EDI) system aiming to improve breakdown behavior has been designed and constructed on the Joint Texas EXperiment Tokamak Tokamak. Electrons emitted by the system undergo the E×B drift, ∇B drift and curvature drift in sequence in order to traverse the confining magnetic field. A local electrostatic well, generated by a concave-shaped plate biased more negative than the cathode, is introduced to interrupt the emitted electrons moving along the magnetic field line (in the parallel direction) in an attempt to bring an enhancement of the injection efficiency and depth. A series of experiments have demonstrated the feasibility of this method, and a penetration distance deeper than 9.5 cm is achieved. Notable breakdown improvements, including the reduction of breakdown delay and average loop voltage, are observed for discharges assisted by EDI. The lower limit of successfully ionized pressure is expanded.

Performance of the improved larger acceptance spectrometer: VAMOS++

NASA Astrophysics Data System (ADS)

Rejmund, M.; Lecornu, B.; Navin, A.; Schmitt, C.; Damoy, S.; Delaune, O.; Enguerrand, J. M.; Fremont, G.; Gangnant, P.; Gaudefroy, L.; Jacquot, B.; Pancin, J.; Pullanhiotan, S.; Spitaels, C.

2011-08-01

Measurements and ion optic calculations showed that the large momentum acceptance of the VAMOS spectrometer at GANIL could be further increased from ˜11% to ˜30% by suitably enlarging the dimensions of the detectors used at the focal plane. Such a new detection system built for the focal plane of VAMOS is described. It consists of larger area detectors (1000 mm×150 mm) namely, a Multi-Wire Parallel Plate Avalanche Counter (MWPPAC), two drift chambers, a segmented ionization chamber and an array of Si detectors. Compared to the earlier existing system (VAMOS), we show that the new system (VAMOS++) has a dispersion-independent momentum acceptance. Additionally, a start detector (MWPPAC) has been introduced near the target to further improve the mass resolution to ˜1/220. The performance of the VAMOS++ spectrometer is demonstrated using measurements of residues formed in the collisions of 129Xe at 967 MeV on 197Au.

[Measurement of the air kerma using dosimeters embedded in an acrylic phantom in interventional radiology.].

PubMed

Kawabe, Atsushi; Shibuya, Koichi; Takeda, Yoshihiro

2006-01-01

Interventional radiology procedure guidelines and a measurement manual (IVR guidelines) have been published for the maintenance of interventional equipment with an objective of avoiding serious radiation-induced skin injuries. In the IVR guidelines, the positioning of a dosimeter at the interventional reference point is determined, whereas placement of a phantom is not specified. Therefore, the phantom is placed at any convenient location between the dosimeter and image intensifier. The space around the dosimeter reduces detection of scattered radiation. In this study, dosimeters (consisting of a parallel plate ionization chamber, glass dosimeter and OSL dosimeter) were embedded in the phantom surface to detected scattered radiation accurately. As a result, when dosimeters were embedded in the phantom surface, the air kerma was increased compared with that when dosimeters were placed on the phantom. This suggested that embedded dosimeters were able to detect scattered radiation from the phantom.

Laser-excited pulses in a crystallized dusty plasma

NASA Astrophysics Data System (ADS)

Nosenko, V.; Nunomura, S.; Goree, J.

2000-10-01

A dusty plasma is an ionized gas containing small particles of solid matter. These particles acquire a large negative electric charge. Polymer microspheres were shaken into a capacitively-coupled parallel-plate rf plasma. The particles were levitated by the electric field in the sheath above the lower electrode. The particles settled in a single horizontal layer, arranged in a hexagonal lattice. They were imaged using a video camera, to record the particle motion. Like any crystal, this so-called ``plasma crystal'' sustains compressional sound waves, which can be launched as a pulse. There are several ways these waves can be excited, including applying a force from the radiation pressure of a laser beam. By chopping an argon laser beam that is directed at the lattice, it is possible to launch a pulsed wave in the lattice. We evaluate the pulse's shape and propagation speed, and test whether it has the properties of a shock.

FUEL ASSEMBLY FOR A NEUTRONIC REACTOR

DOEpatents

Wigner, E.P.

1958-04-29

A fuel assembly for a nuclear reactor of the type wherein liquid coolant is circulated through the core of the reactor in contact with the external surface of the fuel elements is described. In this design a plurality of parallel plates containing fissionable material are spaced about one-tenth of an inch apart and are supported between a pair of spaced parallel side members generally perpendicular to the plates. The plates all have a small continuous and equal curvature in the same direction between the side members.

Electrically-induced stresses and deflection in multiple plates

NASA Astrophysics Data System (ADS)

Hu, Jih-Perng; Tichler, P. R.

1992-04-01

Thermohydraulic tests are being planned at the High Flux Beam Reactor of Brookhaven National Laboratory, in which direct electrical heating of metal plates will simulate decay heating in parallel plate-type fuel elements. The required currents are high if plates are made of metal with a low electrical resistance, such as aluminum. These high currents will induce either attractive or repulsive forces between adjacent current-carrying plates. Such forces, if strong enough, will cause the plates to deflect and so change the geometry of the coolant channel between the plates. Since this is undesirable, an analysis was made to evaluate the magnitude of the deflection and related stresses. In contrast to earlier publications in which either a concentrated or a uniform load was assumed, in this paper an exact force distribution on the plate is analytically solved and then used for stress and deflection calculations, assuming each plate to be a simply supported beam. Results indicate that due to superposition of the induced forces between plates in a multiple-and-parallel plate array, the maximum deflection and bending stress occur at the midpoint of the outermost plate. The maximum shear stress, which is inversely proportional to plate thickness, occurs at both ends of the outermost plate.

Ultrasonically-assisted Thermal Stir Welding System

NASA Technical Reports Server (NTRS)

Ding, R. Jeffrey (Inventor)

2014-01-01

A welding head assembly has a work piece disposed between its containment plates' opposing surfaces with the work piece being maintained in a plastic state thereof at least in a vicinity of the welding head assembly's stir rod as the rod is rotated about its longitudinal axis. The welding head assembly and the work piece experience relative movement there between in a direction perpendicular to the rod's longitudinal axis as the work piece is subjected to a compressive force applied by the containment plates. A first source coupled to the first containment plate applies a first ultrasonic wave thereto such that the first ultrasonic wave propagates parallel to the direction of relative movement. A second source coupled to the second containment plate applies a second ultrasonic wave thereto such that the second ultrasonic wave propagates parallel to the direction of relative movement.propagates parallel to the direction of relative movement.

[Morphology determination of ionization region in multi-needle-to-plate negative corona discharge].

PubMed

Su, Peng-Hao; Zhu, Yi-Min; Chen, Hai-Feng

2007-11-01

Based on the former work on the current-voltage characteristics of a multi-needle-to-plate negative corona discharge at atmospheric pressure, the present work uses the method of OES (optical emission spectrum) for measuring N2 emission spectrum, and the morphology determination of the ionization region has been investigated. According to the distribution of N2 second positive band's intensity I(SPB), the highest of all bands, the outline of the ionization region was drawn fairly accurately. The relationship between I(SPB) and discharge current I can be obtained through the volume integral of the I(SPB). The experimental results show that the size of the ionization region enhances with the rise of the applied voltage U, and the electron avalanche begins at about 1 mm off the tips of needle electrode and multiplies only in the range of several millimeters, indicating that, the range of the ionization region is at the magnitude of mm. The electron avalanche along the axis of the needle develops farther than that along the radial direction of needle, and the shape of the ionization region looks like a bullet. The integral of I(SPB) is second-order linear to I, with a very second order coefficient, meaning that the main excited substance is N2. Energetic electrons mainly exist in ionization region while ions are the main charged particles to form discharge current in the transfer region.

Mechanisms of Ionizing Radiation-Induced Cell Death in Primary Lung Cells

DTIC Science & Technology

2013-03-05

haemocytometer, and plated on 60 mm dishes coated with 0.5% gelatin (modification to allow attachment of PAEC). The cells were incubated for 14 days...we performed delayed plating where PAEC were first cultured to 70-90% confluence, exposed to varying doses of X-rays, incubated, and seeded then for...calculated as a function of plating efficiency of non-irradiated controls. The plating efficiency (PE) was defined as the percentage of the number

Building blocks for the development of an interface for high-throughput thin layer chromatography/ambient mass spectrometric analysis: a green methodology.

PubMed

Cheng, Sy-Chyi; Huang, Min-Zong; Wu, Li-Chieh; Chou, Chih-Chiang; Cheng, Chu-Nian; Jhang, Siou-Sian; Shiea, Jentaie

2012-07-17

Interfacing thin layer chromatography (TLC) with ambient mass spectrometry (AMS) has been an important area of analytical chemistry because of its capability to rapidly separate and characterize the chemical compounds. In this study, we have developed a high-throughput TLC-AMS system using building blocks to deal, deliver, and collect the TLC plate through an electrospray-assisted laser desorption ionization (ELDI) source. This is the first demonstration of the use of building blocks to construct and test the TLC-MS interfacing system. With the advantages of being readily available, cheap, reusable, and extremely easy to modify without consuming any material or reagent, the use of building blocks to develop the TLC-AMS interface is undoubtedly a green methodology. The TLC plate delivery system consists of a storage box, plate dealing component, conveyer, light sensor, and plate collecting box. During a TLC-AMS analysis, the TLC plate was sent to the conveyer from a stack of TLC plates placed in the storage box. As the TLC plate passed through the ELDI source, the chemical compounds separated on the plate would be desorbed by laser desorption and subsequently postionized by electrospray ionization. The samples, including a mixture of synthetic dyes and extracts of pharmaceutical drugs, were analyzed to demonstrate the capability of this TLC-ELDI/MS system for high-throughput analysis.

Surface tuning laser desorption/ionization mass spectrometry (STLDI-MS) for the analysis of small molecules using quantum dots.

PubMed

Abdelhamid, Hani Nasser; Chen, Zhen-Yu; Wu, Hui-Fen

2017-08-01

In most applications of quantum dots (QDs) for surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS), one side of QDs is supported by a solid substrate (stainless - steel plate), whereas the other side is in contact with the target analytes. Therefore, the surface capping agent of QDs is a key parameter for laser desorption/ionization mass spectrometry (LDI-MS). Cadmium telluride quantum dots (CdTe QDs) modified with different capping agents are synthesized, characterized, and applied for surface tuning laser desorption/ionization mass spectrometry (STLDI-MS). Data shows that CdTe quantum dot modified cysteine (cys@CdTe QDs) has an absorption that matches with the wavelength of the N 2 laser (337 nm). The synergistic effect of large surface area and absorption of the laser irradiation of cys@CdTe QDs enhances the LDI-MS process for small - molecule analysis, including α-, β-, and γ-cyclodextrin, gramicidin D, perylene, pyrene, and triphenylphosphine. Cys@CdTe QDs are also applied using Al foils as substrates. Aluminum foil combined with cys@CdTe QDs enhances the ionization efficiency and is cheap compared to traditional matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) with a stainless - steel plate.

Numerical Simulation of Flow Field Within Parallel Plate Plastometer

NASA Technical Reports Server (NTRS)

Antar, Basil N.

2002-01-01

Parallel Plate Plastometer (PPP) is a device commonly used for measuring the viscosity of high polymers at low rates of shear in the range 10(exp 4) to 10(exp 9) poises. This device is being validated for use in measuring the viscosity of liquid glasses at high temperatures having similar ranges for the viscosity values. PPP instrument consists of two similar parallel plates, both in the range of 1 inch in diameter with the upper plate being movable while the lower one is kept stationary. Load is applied to the upper plate by means of a beam connected to shaft attached to the upper plate. The viscosity of the fluid is deduced from measuring the variation of the plate separation, h, as a function of time when a specified fixed load is applied on the beam. Operating plate speeds measured with the PPP is usually in the range of 10.3 cm/s or lower. The flow field within the PPP can be simulated using the equations of motion of fluid flow for this configuration. With flow speeds in the range quoted above the flow field between the two plates is certainly incompressible and laminar. Such flows can be easily simulated using numerical modeling with computational fluid dynamics (CFD) codes. We present below the mathematical model used to simulate this flow field and also the solutions obtained for the flow using a commercially available finite element CFD code.

A mode-matching analysis of dielectric-filled resonant cavities coupled to terahertz parallel-plate waveguides.

PubMed

Astley, Victoria; Reichel, Kimberly S; Jones, Jonathan; Mendis, Rajind; Mittleman, Daniel M

2012-09-10

We use the mode-matching technique to study parallel-plate waveguide resonant cavities that are filled with a dielectric. We apply the generalized scattering matrix theory to calculate the power transmission through the waveguide-cavities. We compare the analytical results to experimental data to confirm the validity of this approach.

Analysis of rectangular resonant cavities in terahertz parallel-plate waveguides.

PubMed

Astley, Victoria; McCracken, Blake; Mendis, Rajind; Mittleman, Daniel M

2011-04-15

We describe an experimental and theoretical characterization of rectangular resonant cavities integrated into parallel-plate waveguides, using terahertz pulses. When the waveguide is excited with the lowest-order transverse-electric mode, these cavities exhibit resonances with narrow linewidths. Broadband transmission spectra are compared with the results of mode-matching calculations, for various cavity dimensions.

WET EFFLUENT PARALLEL PLATE DIFFUSION DENUDER COUPLED CAPILLARY ION CHROMATOGRAPH FOR THE DETERMINATION OF ATMOSPHERIC TRACE GASES. (R825344)

EPA Science Inventory

We describe an inexpensive, compact parallel plate diffusion denuder coupled capillary IC system for the determination of soluble ionogenic atmospheric trace gases. The active sampling area (0.6×10 cm) of the denuder is formed in a novel manner by thermally bonding silica ge...

Effective ionization coefficient of C5 perfluorinated ketone and its mixtures with air

NASA Astrophysics Data System (ADS)

Aints, Märt; Jõgi, Indrek; Laan, Matti; Paris, Peeter; Raud, Jüri

2018-04-01

C5 perfluorinated ketone (C5 PFK with UIPAC chemical name 1,1,1,3,4,4,4-heptafluoro-3-(trifluoromethyl)-2-butanone and sold by 3M as Novec™ 5110) has a high dielectric strength and a low global warming potential, which makes it interesting as an insulating gas in medium and high-voltage applications. The study was carried out to determine the effective Townsend ionization coefficient α eff as a function of electric field strength and gas density for C5 PFK and for its mixtures with air. The non-self-sustained Townsend discharge between parallel plate electrodes was initiated by illuminating the cathode by UV radiation. The discharge current, I, was measured as a function of inter-electrode distance, d, at different gas densities, N, and electric field strengths, E. The effective ionization coefficient α eff was determined from the semi-logarithmic plots of I/I 0 against d. For each tested gas mixture, the density normalized effective ionization coefficient α eff/N was found to be a unique function of reduced electric field strength E/N. The measurements were carried out in the absolute pressure range of 0.05-1.3 bar and E/N range of 150-1200 Td. The increasing fraction of C5 PFK in air resulted in the decrease of effective ionization coefficient. The limiting electric field strength (E/N)lim where the effective ionization coefficient α eff became zero was 770 Td (190 kV cm-1 at 1 bar) for pure C5 PFK and decreased to 225 Td (78 kV cm-1 at 1.4 bar) for 7.6% C5 PFK/air mixture. The latter value of (E/N)lim is still more than two times higher than the (E/N)lim value of synthetic air and about two-thirds of the value corresponding to pure SF6. The investigated gas mixtures have the potential to become an alternative to SF6 in numerous high- and medium-voltage applications.

Electrically-induced stresses and deflection in multiple plates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hu, Jih-Perng; Tichler, P.R.

Thermohydraulic tests are being planned at the High Flux Beam Reactor of Brookhaven National Laboratory, in which direct electrical heating of metal plates will simulate decay heating in parallel plate-type fuel elements. The required currents are high if plates are made of metal with a low electrical resistance, such as aluminum. These high currents will induce either attractive or repulsive forces between adjacent current-carrying plates. Such forces, if strong enough, will cause the plates to deflect and so change the geometry of the coolant channel between the plates. Since this is undesirable, an analysis has been made to evaluate themore » magnitude of the deflection and related stresses. In contrast to earlier publications in which either a concentrated or a uniform load was assumed, in this paper an exact force distribution on the plate is analytically solved and then used for stress and deflection calculations, assuming each plate to be a simply supported beam. Results indicate that due to superposition of the induced forces between plates in a multiple-and-parallel plate array, the maximum deflection and bending stress occur at the midpoint of the outermost plate. The maximum shear stress, which is inversely proportional to plate thickness, occurs at both ends of the outermost plate.« less

All-Optical Two-Dimensional Serial-to-Parallel Pulse Converter Using an Organic Film with Femtosecond Optical Response

NASA Astrophysics Data System (ADS)

Tatsuura, Satoshi; Wada, Osamu; Furuki, Makoto; Tian, Minquan; Sato, Yasuhiro; Iwasa, Izumi; Pu, Lyong Sun

2001-04-01

In this study, we introduce a new concept of all-optical two-dimensional serial-to-parallel pulse converters. Femtosecond optical pulses can be understood as thin plates of light traveling in space. When a femtosecond signal-pulse train and a single gate pulse were fed onto a material with a finite incident angle, each signal-pulse plate met the gate-pulse plate at different locations in the material due to the time-of-flight effect. Meeting points can be made two-dimensional by adding a partial time delay to the gate pulse. By placing a nonlinear optical material at an appropriate position, two-dimensional serial-to-parallel conversion of a signal-pulse train can be achieved with a single gate pulse. We demonstrated the detection of parallel outputs from a 1-Tb/s optical-pulse train through the use of a BaB2O4 crystal. We also succeeded in demonstrating 1-Tb/s serial-to-parallel operation through the use of a novel organic nonlinear optical material, squarylium-dye J-aggregate film, which exhibits ultrafast recovery of bleached absorption.

Analysis of Heat Transfer and Pressure Drop for a Gas Flowing Through a set of Multiple Parallel Flat Plates at High Temperatures

NASA Technical Reports Server (NTRS)

Einstein, Thomas H.

1961-01-01

Equations were derived representing heat transfer and pressure drop for a gas flowing in the passages of a heater composed of a series of parallel flat plates. The plates generated heat which was transferred to the flowing gas by convection. The relatively high temperature level of this system necessitated the consideration of heat transfer between the plates by radiation. The equations were solved on an IBM 704 computer, and results were obtained for hydrogen as the working fluid for a series of cases with a gas inlet temperature of 200 R, an exit temperature of 5000 0 R, and exit Mach numbers ranging from 0.2 to O.8. The length of the heater composed of the plates ranged from 2 to 4 feet, and the spacing between the plates was varied from 0.003 to 0.01 foot. Most of the results were for a five- plate heater, but results are also given for nine plates to show the effect of increasing the number of plates. The heat generation was assumed to be identical for each plate but was varied along the length of the plates. The axial variation of power used to obtain the results presented is the so-called "2/3-cosine variation." The boundaries surrounding the set of plates, and parallel to it, were assumed adiabatic, so that all the power generated in the plates went into heating the gas. The results are presented in plots of maximum plate and maximum adiabatic wall temperatures as functions of parameters proportional to f(L/D), for the case of both laminar and turbulent flow. Here f is the Fanning friction factor and (L/D) is the length to equivalent diameter ratio of the passages in the heater. The pressure drop through the heater is presented as a function of these same parameters, the exit Mach number, and the pressure at the exit of the heater.

High precision refractometry based on Fresnel diffraction from phase plates.

PubMed

Tavassoly, M Taghi; Naraghi, Roxana Rezvani; Nahal, Arashmid; Hassani, Khosrow

2012-05-01

When a transparent plane-parallel plate is illuminated at a boundary region by a monochromatic parallel beam of light, Fresnel diffraction occurs because of the abrupt change in phase imposed by the finite change in refractive index at the plate boundary. The visibility of the diffraction fringes varies periodically with changes in incident angle. The visibility period depends on the plate thickness and the refractive indices of the plate and the surrounding medium. Plotting the phase change versus incident angle or counting the visibility repetition in an incident-angle interval provides, for a given plate thickness, the refractive index of the plate very accurately. It is shown here that the refractive index of a plate can be determined without knowing the plate thickness. Therefore, the technique can be utilized for measuring plate thickness with high precision. In addition, by installing a plate with known refractive index in a rectangular cell filled with a liquid and following the described procedures, the refractive index of the liquid is obtained. The technique is applied to measure the refractive indices of a glass slide, distilled water, and ethanol. The potential and merits of the technique are also discussed.

Focused terahertz waves generated by a phase velocity gradient in a parallel-plate waveguide.

PubMed

McKinney, Robert W; Monnai, Yasuaki; Mendis, Rajind; Mittleman, Daniel

2015-10-19

We demonstrate the focusing of a free-space THz beam emerging from a leaky parallel-plate waveguide (PPWG). Focusing is accomplished by grading the launch angle of the leaky wave using a PPWG with gradient plate separation. Inside the PPWG, the phase velocity of the guided TE1 mode exceeds the vacuum light speed, allowing the wave to leak into free space from a slit cut along the top plate. Since the leaky wave angle changes as the plate separation decreases, the beam divergence can be controlled by grading the plate separation along the propagation axis. We experimentally demonstrate focusing of the leaky wave at a selected location at frequencies of 100 GHz and 170 GHz, and compare our measurements with numerical simulations. The proposed concept can be valuable for implementing a flat and wide-aperture beam-former for THz communications systems.

CALUTRON ION SOURCE

DOEpatents

Brobeck, W.M.

1959-02-24

An ion source is described wherein a portion of the filament serving as a cathode for the arc is protected from the effects of non-ionized particles escaping from the ionizing mechanism. In the described ion source, the source block has a gas chamber and a gas passage extending from said gas chamber to two adjacent faces of the source block. A plate overlies the passage and abuts one of the aforementioned block faces, while extending beyond the other face. In addition, the plate is apertured in line with the block passage. The filament overlies the aperture to effectively shield the portion of the filament not directiy aligned with the passage where the arc is produced.

Three-Point Gear/Lead Screw Positioning

NASA Technical Reports Server (NTRS)

Calco, Frank S.

1993-01-01

Triple-ganged-lead-screw positioning mechanism drives movable plate toward or away from fixed plate and keeps plates parallel to each other. Designed for use in tuning microwave resonant cavity. Other potential applications include adjustable bed plates and cantilever tail stocks in machine tools, adjustable platforms for optical equipment, and lifting platforms.

Clinico-radiological Outcome Analysis of Parallel Plating with Perpendicular Plating in Distal Humeral Intra-articular Fractures: Prospective Randomised Study

PubMed Central

Shekhawat, Vishal; Banshiwal, Ramesh Chandra; Verma, Rajender Kumar

2017-01-01

Introduction The distal humeral fractures are common fractures of upper limb and are difficult to treat. These fractures, if left untreated or inadequately treated, leads to poor outcomes. Management of distal humeral fractures are pertained to many controversies and one among them is position of plates. Aim To compare the clinical and radiological outcomes in patients with intra-articular distal humerus fractures, treated using parallel and perpendicular double plating methods. Materials and Methods A total of 38 patients with distal humerus fractures, 20 in perpendicular plating group (group A) and 18 in parallel plating group (group B), were included in this prospective randomised study. At each follow up patients were evaluated clinically and radiologically for union and the outcomes were measured in terms of Mayo Elbow Performance Score (MEPS) consisting of pain intensity, range of motion, stability and function. MEP score greater than 90 is considered as excellent; Score 75 to 89 is good; Score 60 to 74 is fair and Score less than 60 is poor. Results In our study, 15 patients (75%) in group A, and 13 patients (72.22%) in group B achieved excellent results. Two patients (10%) in group A and 4 patients (22.22%) in group B attained good results. Complications developed in 2 patients in each groups. No significant differences were found between the clinical outcomes of the two plating methods. Conclusion Neither of the plating techniques are superior to the other, as inferred from the insignificant differences in bony union, elbow function and complications between the two plating techniques. PMID:28384948

Clinico-radiological Outcome Analysis of Parallel Plating with Perpendicular Plating in Distal Humeral Intra-articular Fractures: Prospective Randomised Study.

PubMed

Govindasamy, Ramachandran; Shekhawat, Vishal; Banshiwal, Ramesh Chandra; Verma, Rajender Kumar

2017-02-01

The distal humeral fractures are common fractures of upper limb and are difficult to treat. These fractures, if left untreated or inadequately treated, leads to poor outcomes. Management of distal humeral fractures are pertained to many controversies and one among them is position of plates. To compare the clinical and radiological outcomes in patients with intra-articular distal humerus fractures, treated using parallel and perpendicular double plating methods. A total of 38 patients with distal humerus fractures, 20 in perpendicular plating group (group A) and 18 in parallel plating group (group B), were included in this prospective randomised study. At each follow up patients were evaluated clinically and radiologically for union and the outcomes were measured in terms of Mayo Elbow Performance Score (MEPS) consisting of pain intensity, range of motion, stability and function. MEP score greater than 90 is considered as excellent; Score 75 to 89 is good; Score 60 to 74 is fair and Score less than 60 is poor. In our study, 15 patients (75%) in group A, and 13 patients (72.22%) in group B achieved excellent results. Two patients (10%) in group A and 4 patients (22.22%) in group B attained good results. Complications developed in 2 patients in each groups. No significant differences were found between the clinical outcomes of the two plating methods. Neither of the plating techniques are superior to the other, as inferred from the insignificant differences in bony union, elbow function and complications between the two plating techniques.

Modeling and Characterization of Capacitive Elements With Tissue as Dielectric Material for Wireless Powering of Neural Implants.

PubMed

Erfani, Reza; Marefat, Fatemeh; Sodagar, Amir M; Mohseni, Pedram

2018-05-01

This paper reports on the modeling and characterization of capacitive elements with tissue as the dielectric material, representing the core building block of a capacitive link for wireless power transfer to neural implants. Each capacitive element consists of two parallel plates that are aligned around the tissue layer and incorporate a grounded, guarded, capacitive pad to mitigate the adverse effect of stray capacitances and shield the plates from external interfering electric fields. The plates are also coated with a biocompatible, insulating, coating layer on the inner side of each plate in contact with the tissue. A comprehensive circuit model is presented that accounts for the effect of the coating layers and is validated by measurements of the equivalent capacitance as well as impedance magnitude/phase of the parallel plates over a wide frequency range of 1 kHz-10 MHz. Using insulating coating layers of Parylene-C at a thickness of and Parylene-N at a thickness of deposited on two sets of parallel plates with different sizes and shapes of the guarded pad, our modeling and characterization results accurately capture the effect of the thickness and electrical properties of the coating layers on the behavior of the capacitive elements over frequency and with different tissues.

The buckling response of symmetrically laminated composite plates having a trapezoidal planform area. M.S. Thesis Interim Report No. 98, Aug. 1990 - May 1994

NASA Technical Reports Server (NTRS)

Radloff, H. D., II; Hyer, M. W.; Nemeth, M. P.

1994-01-01

The focus of this work is the buckling response of symmetrically laminated composite plates having a planform area in the shape of an isosceles trapezoid. The loading is assumed to be inplane and applied perpendicular to the parallel ends of the plate. The tapered edges of the plate are assumed to have simply supported boundary conditions, while the parallel ends are assumed to have either simply supported or clamped boundary conditions. A semi-analytic closed-form solution based on energy principles and the Trefftz stability criterion is derived and solutions are obtained using the Rayleigh-Ritz method. Intrinsic in this solution is a simplified prebuckling analysis which approximates the inplane force resultant distributions by the forms Nx=P/W(x) and Ny=Nxy=0, where P is the applied load and W(x) is the plate width which, for the trapezoidal planform, varies linearly with the lengthwise coordinate x. The out-of-plane displacement is approximated by a double trigonometric series. This analysis is posed in terms of four nondimensional parameters representing orthotropic and anisotropic material properties, and two nondimensional parameters representing geometric properties. For comparison purposes, a number of specific plate geometry, ply orientation, and stacking sequence combinations are investigated using the general purpose finite element code ABAQUS. Comparison of buckling coefficients calculated using the semi-analytical model and the finite element model show agreement within 5 percent, in general, and within 15 percent for the worst cases. In order to verify both the finite element and semi-analytical analyses, buckling loads are measured for graphite/epoxy plates having a wide range of plate geometries and stacking sequences. Test fixtures, instrumentation system, and experimental technique are described. Experimental results for the buckling load, the buckled mode shape, and the prebuckling plate stiffness are presented and show good agreement with the analytical results regarding the buckling load and the prebuckling plate stiffness. However, the experimental results show that for some cases the analysis underpredicts the number of halfwaves in the buckled mode shape. In the context of the definitions of taper ratio and aspect ratio used in this study, it is concluded that the buckling load always increases as taper ratio increases for a given aspect ratio for plates having simply supported boundary conditions on the parallel ends. There are combinations of plate geometry and ply stackling sequences, however, that reverse this trend for plates having clamped boundary conditions on the parallel ends such that an increase in the taper ratio causes a decrease in the buckling load. The clamped boundary conditions on the parallel ends of the plate are shown to increase the buckling load compared to simply supported boundary conditions. Also, anisotropy (the D16 and D26 terms) is shown to decrease the buckling load and skew the buckled mode shape for both the simply supported and clamped boundary conditions.

The restoring force on a dielectric in a parallel plate capacitor

NASA Astrophysics Data System (ADS)

Staunton, L. P.

2014-09-01

We investigate the restoring force on a dielectric slab being pulled from within the volume of a parallel plate capacitor connected to a battery. Using a conformal mapping to treat the fringing electric field exactly, we numerically obtain an expected Hooke's Law restoring force for small displacements, and a diminishing force for a displacement up to half the length of the dielectric.

A multi-component parallel-plate flow chamber system for studying the effect of exercise-induced wall shear stress on endothelial cells.

PubMed

Wang, Yan-Xia; Xiang, Cheng; Liu, Bo; Zhu, Yong; Luan, Yong; Liu, Shu-Tian; Qin, Kai-Rong

2016-12-28

In vivo studies have demonstrated that reasonable exercise training can improve endothelial function. To confirm the key role of wall shear stress induced by exercise on endothelial cells, and to understand how wall shear stress affects the structure and the function of endothelial cells, it is crucial to design and fabricate an in vitro multi-component parallel-plate flow chamber system which can closely replicate exercise-induced wall shear stress waveforms in artery. The in vivo wall shear stress waveforms from the common carotid artery of a healthy volunteer in resting and immediately after 30 min acute aerobic cycling exercise were first calculated by measuring the inner diameter and the center-line blood flow velocity with a color Doppler ultrasound. According to the above in vivo wall shear stress waveforms, we designed and fabricated a parallel-plate flow chamber system with appropriate components based on a lumped parameter hemodynamics model. To validate the feasibility of this system, human umbilical vein endothelial cells (HUVECs) line were cultured within the parallel-plate flow chamber under abovementioned two types of wall shear stress waveforms and the intracellular actin microfilaments and nitric oxide (NO) production level were evaluated using fluorescence microscope. Our results show that the trends of resting and exercise-induced wall shear stress waveforms, especially the maximal, minimal and mean wall shear stress as well as oscillatory shear index, generated by the parallel-plate flow chamber system are similar to those acquired from the common carotid artery. In addition, the cellular experiments demonstrate that the actin microfilaments and the production of NO within cells exposed to the two different wall shear stress waveforms exhibit different dynamic behaviors; there are larger numbers of actin microfilaments and higher level NO in cells exposed in exercise-induced wall shear stress condition than resting wall shear stress condition. The parallel-plate flow chamber system can well reproduce wall shear stress waveforms acquired from the common carotid artery in resting and immediately after exercise states. Furthermore, it can be used for studying the endothelial cells responses under resting and exercise-induced wall shear stress environments in vitro.

Self-stabilized discharge filament in plane-parallel barrier discharge configuration: formation, breakdown mechanism, and memory effects

NASA Astrophysics Data System (ADS)

Tschiersch, R.; Nemschokmichal, S.; Bogaczyk, M.; Meichsner, J.

2017-10-01

Single self-stabilized discharge filaments were investigated in the plane-parallel electrode configuration. The barrier discharge was operated inside a gap of 3 mm shielded by glass plates to both electrodes, using helium-nitrogen mixtures and a square-wave feeding voltage at a frequency of 2 kHz. The combined application of electrical measurements, ICCD camera imaging, optical emission spectroscopy and surface charge diagnostics via the electro-optic Pockels effect allowed the correlation of the discharge development in the volume and on the dielectric surfaces. The formation criteria and existence regimes were found by systematic variation of the nitrogen admixture to helium, the total pressure and the feeding voltage amplitude. Single self-stabilized discharge filaments can be operated over a wide parameter range, foremost, by significant reduction of the voltage amplitude after the operation in the microdischarge regime. Here, the outstanding importance of the surface charge memory effect on the long-term stability was pointed out by the recalculated spatio-temporally resolved gap voltage. The optical emission revealed discharge characteristics that are partially reminiscent of both the glow-like barrier discharge and the microdischarge regime, such as a Townsend pre-phase, a fast cathode-directed ionization front during the breakdown and radially propagating surface discharges during the afterglow.

Retrieval of the thickness and refractive index dispersion of parallel plate from a single interferogram recorded in both spectral and angular domains

NASA Astrophysics Data System (ADS)

Dong, Jingtao; Lu, Rongsheng

2018-04-01

The principle of retrieving the thickness and refractive index dispersion of a parallel glass plate is reported based on single interferogram recording and phase analysis. With the parallel plate illuminated by a convergent light sheet, the transmitted light interfering in both spectral and angular domains is recorded. The phase recovered from the single interferogram by Fourier analysis is used to retrieve the thickness and refractive index dispersion without periodic ambiguity. Experimental results of an optical substrate standard show that the accuracy of refractive index dispersion is less than 2.5 × 10-5 and the relative uncertainty of thickness is 6 × 10-5 (3σ). This method is confirmed to be robust against the intensity noises, indicating the capability of stable and accurate measurement.

Two-dimensional numerical simulation of a Stirling engine heat exchanger

NASA Technical Reports Server (NTRS)

Ibrahim, Mounir; Tew, Roy C.; Dudenhoefer, James E.

1989-01-01

The first phase of an effort to develop multidimensional models of Stirling engine components is described. The ultimate goal is to model an entire engine working space. Parallel plate and tubular heat exchanger models are described, with emphasis on the central part of the channel (i.e., ignoring hydrodynamic and thermal end effects). The model assumes laminar, incompressible flow with constant thermophysical properties. In addition, a constant axial temperature gradient is imposed. The governing equations describing the model have been solved using the Crack-Nicloson finite-difference scheme. Model predictions are compared with analytical solutions for oscillating/reversing flow and heat transfer in order to check numerical accuracy. Excellent agreement is obtained for flow both in circular tubes and between parallel plates. The computational heat transfer results are in good agreement with the analytical heat transfer results for parallel plates.

Binary zone-plate array for a parallel joint transform correlator applied to face recognition.

PubMed

Kodate, K; Hashimoto, A; Thapliya, R

1999-05-10

Taking advantage of small aberrations, high efficiency, and compactness, we developed a new, to our knowledge, design procedure for a binary zone-plate array (BZPA) and applied it to a parallel joint transform correlator for the recognition of the human face. Pairs of reference and unknown images of faces are displayed on a liquid-crystal spatial light modulator (SLM), Fourier transformed by the BZPA, intensity recorded on an optically addressable SLM, and inversely Fourier transformed to obtain correlation signals. Consideration of the bandwidth allows the relations among the channel number, the numerical aperture of the zone plates, and the pattern size to be determined. Experimentally a five-channel parallel correlator was implemented and tested successfully with a 100-person database. The design and the fabrication of a 20-channel BZPA for phonetic character recognition are also included.

Electromagnetic pulse coupling through an aperture into a two-parallel-plate region

NASA Technical Reports Server (NTRS)

Rahmat-Samii, Y.

1978-01-01

Analysis of electromagnetic-pulse (EMP) penetration via apertures into cavities is an important study in designing hardened systems. In this paper, an integral equation procedure is developed for determining the frequency and consequently the time behavior of the field inside a two-parallel-plate region excited through an aperture by an EMP. Some discussion of the numerical results is also included in the paper for completeness.

Self-organization and self-limitation in high power impulse magnetron sputtering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anders, Andre

The plasma over the racetrack in high power impulse magnetron sputtering develops in traveling ionization zones. Power densities can locally reach 10{sup 9} W/m{sup 2}, which is much higher than usually reported. Ionization zones move because ions are 'evacuated' by the electric field, exposing neutrals to magnetically confined, drifting electrons. Drifting secondary electrons amplify ionization of the same ionization zone where the primary ions came from, while sputtered and outgassing atoms are supplied to the following zone(s). Strong density gradients parallel to the target disrupt electron confinement: a negative feedback mechanism that stabilizes ionization runaway.

Finite Element Analysis of Magnetoelastic Plate Problems.

DTIC Science & Technology

1981-08-01

deformation and in the incremental large deformation analysis, respectively. The classical Kirchhoff assumption of the undeformable normal to the midsurface is...current density , is constant across the thickness of the plate and is parallel to the midsurface of the plate; (2) the normal component of the

LiF TLD-100 as a Dosimeter in High Energy Proton Beam Therapy-Can It Yield Accurate Results?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zullo, John R.; Kudchadker, Rajat J.; Zhu, X. Ronald

In the region of high-dose gradients at the end of the proton range, the stopping power ratio of the protons undergoes significant changes, allowing for a broad spectrum of proton energies to be deposited within a relatively small volume. Because of the potential linear energy transfer dependence of LiF TLD-100 (thermolumescent dosimeter), dose measurements made in the distal fall-off region of a proton beam may be less accurate than those made in regions of low-dose gradients. The purpose of this study is to determine the accuracy and precision of dose measured using TLD-100 for a pristine Bragg peak, particularly inmore » the distal fall-off region. All measurements were made along the central axis of an unmodulated 200-MeV proton beam from a Probeat passive beam-scattering proton accelerator (Hitachi, Ltd., Tokyo, Japan) at varying depths along the Bragg peak. Measurements were made using TLD-100 powder flat packs, placed in a virtual water slab phantom. The measurements were repeated using a parallel plate ionization chamber. The dose measurements using TLD-100 in a proton beam were accurate to within {+-}5.0% of the expected dose, previously seen in our past photon and electron measurements. The ionization chamber and the TLD relative dose measurements agreed well with each other. Absolute dose measurements using TLD agreed with ionization chamber measurements to within {+-} 3.0 cGy, for an exposure of 100 cGy. In our study, the differences in the dose measured by the ionization chamber and those measured by TLD-100 were minimal, indicating that the accuracy and precision of measurements made in the distal fall-off region of a pristine Bragg peak is within the expected range. Thus, the rapid change in stopping power ratios at the end of the range should not affect such measurements, and TLD-100 may be used with confidence as an in vivo dosimeter for proton beam therapy.« less

MEMS closed-loop control incorporating a memristor as feedback sensing element

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garcia, Ernest J.; Almeida, Sergio F.; Mireles, Jr., Jose

In this work the integration of a memristor with a MEMS parallel plate capacitor coupled by an amplification stage is simulated. It is shown that the MEMS upper plate position can be controlled up to 95% of the total gap. Due to its common operation principle, the change in the MEMS plate position can be interpreted by the change in the memristor resistance, or memristance. A memristance modulation of ~1 KΩ was observed. A polynomial expression representing the MEMS upper plate displacement as a function of the memristance is presented. Thereafter a simple design for a voltage closed-loop control ismore » presented showing that the MEMS upper plate can be stabilized up to 95% of the total gap using the memristor as a feedback sensing element. As a result, the memristor can play important dual roles in overcoming the limited operation range of MEMS parallel plate capacitors and in simplifying read-out circuits of those devices by representing the motion of the upper plate in the form of resistance change instead of capacitance change.« less

MEMS closed-loop control incorporating a memristor as feedback sensing element

DOE PAGES

Garcia, Ernest J.; Almeida, Sergio F.; Mireles, Jr., Jose; ...

2015-12-01

In this work the integration of a memristor with a MEMS parallel plate capacitor coupled by an amplification stage is simulated. It is shown that the MEMS upper plate position can be controlled up to 95% of the total gap. Due to its common operation principle, the change in the MEMS plate position can be interpreted by the change in the memristor resistance, or memristance. A memristance modulation of ~1 KΩ was observed. A polynomial expression representing the MEMS upper plate displacement as a function of the memristance is presented. Thereafter a simple design for a voltage closed-loop control ismore » presented showing that the MEMS upper plate can be stabilized up to 95% of the total gap using the memristor as a feedback sensing element. As a result, the memristor can play important dual roles in overcoming the limited operation range of MEMS parallel plate capacitors and in simplifying read-out circuits of those devices by representing the motion of the upper plate in the form of resistance change instead of capacitance change.« less

Aperture-based antihydrogen gravity experiment: Parallel plate geometry

NASA Astrophysics Data System (ADS)

Rocha, J. R.; Hedlof, R. M.; Ordonez, C. A.

2013-10-01

An analytical model and a Monte Carlo simulation are presented of an experiment that could be used to determine the direction of the acceleration of antihydrogen due to gravity. The experiment would rely on methods developed by existing antihydrogen research collaborations. The configuration consists of two circular, parallel plates that have an axis of symmetry directed away from the center of the earth. The plates are separated by a small vertical distance, and include one or more pairs of circular barriers that protrude from the upper and lower plates, thereby forming an aperture between the plates. Antihydrogen annihilations that occur just beyond each barrier, within a "shadow" region, are asymmetric on the upper plate relative to the lower plate. The probability for such annihilations is determined for a point, line and spheroidal source of antihydrogen. The production of 100,000 antiatoms is predicted to be necessary for the aperture-based experiment to indicate the direction of free fall acceleration of antimatter, provided that antihydrogen is produced within a sufficiently small antiproton plasma at a temperature of 4 K.

Two discharge modes of a repetitive nanosecond pulsed helium glow discharge under sub-atmospheric pressure in the repetition frequency range of 20 to 600 kHz

NASA Astrophysics Data System (ADS)

Kikuchi, Yusuke; Maegawa, Takuya; Otsubo, Akira; Nishimura, Yoshimi; Nagata, Masayoshi; Yatsuzuka, Mitsuyasu

2018-05-01

Two discharge modes, α and γ, of a repetitive nanosecond pulsed helium glow discharge at a gas pressure of 10 kPa in the repetition frequency range from 20 to 600 kHz are reported for the first time. The pulsed glow discharge is produced in a pair of parallel plate metal electrodes without insertion of dielectrics. The α mode discharge is volumetrically produced in the electrode gap at a low-repetition frequency, whereas the γ mode discharge is localized at the cathode surface at a high-repetition frequency. At high-repetition frequency, the time interval between voltage pulses is shorter than the lifetime of the afterglow produced by the preceding discharge. Then, the γ mode discharge is maintained by a large number of secondary electrons emitted from the cathode exposed to high-density ions and metastable helium atoms in the afterglow. In the α mode discharge with a low-repetition frequency operation, primary electrons due to gas ionization dominate the ionization process. Thus, a large discharge voltage is needed for the excitation of the α mode discharge. It is established that the bifurcation of α-γ discharge mode, accompanied by a decrease in the discharge voltage, occurs at the high-repetition frequency of ∼120 kHz.

Two-dimensional numerical simulation of a Stirling engine heat exchanger

NASA Technical Reports Server (NTRS)

Ibrahim, Mounir B.; Tew, Roy C.; Dudenhoefer, James E.

1989-01-01

The first phase of an effort to develop multidimensional models of Stirling engine components is described; the ultimate goal is to model an entire engine working space. More specifically, parallel plate and tubular heat exchanger models with emphasis on the central part of the channel (i.e., ignoring hydrodynamic and thermal end effects) are described. The model assumes: laminar, incompressible flow with constant thermophysical properties. In addition, a constant axial temperature gradient is imposed. The governing equations, describing the model, were solved using Crank-Nicloson finite-difference scheme. Model predictions were compared with analytical solutions for oscillating/reversing flow and heat transfer in order to check numerical accuracy. Excellent agreement was obtained for the model predictions with analytical solutions available for both flow in circular tubes and between parallel plates. Also the heat transfer computational results are in good agreement with the heat transfer analytical results for parallel plates.

Numerical study of the stress-strain state of reinforced plate on an elastic foundation by the Bubnov-Galerkin method

NASA Astrophysics Data System (ADS)

Beskopylny, Alexey; Kadomtseva, Elena; Strelnikov, Grigory

2017-10-01

The stress-strain state of a rectangular slab resting on an elastic foundation is considered. The slab material is isotropic. The slab has stiffening ribs that directed parallel to both sides of the plate. Solving equations are obtained for determining the deflection for various mechanical and geometric characteristics of the stiffening ribs which are parallel to different sides of the plate, having different rigidity for bending and torsion. The calculation scheme assumes an orthotropic slab having different cylindrical stiffness in two mutually perpendicular directions parallel to the reinforcing ribs. An elastic foundation is adopted by Winkler model. To determine the deflection the Bubnov-Galerkin method is used. The deflection is taken in the form of an expansion in a series with unknown coefficients by special polynomials, which are a combination of Legendre polynomials.

Electromagnetic Design of a Magnetically-Coupled Spatial Power Combiner

NASA Technical Reports Server (NTRS)

Bulcha, B.; Cataldo, G.; Stevenson, T. R.; U-Yen, K.; Moseley, S. H.; Wollack, E. J.

2017-01-01

The design of a two-dimensional beam-combining network employing a parallel-plate superconducting waveguide with a mono-crystalline silicon dielectric is presented. This novel beam-combining network structure employs an array of magnetically coupled antenna elements to achieve high coupling efficiency and full sampling of the intensity distribution while avoiding diffractive losses in the multi-mode region defined by the parallel-plate waveguide. These attributes enable the structures use in realizing compact far-infrared spectrometers for astrophysical and instrumentation applications. When configured with a suitable corporate-feed power-combiner, this fully sampled array can be used to realize a low-sidelobe apodized response without incurring a reduction in coupling efficiency. To control undesired reflections over a wide range of angles in the finite-sized parallel-plate waveguide region, a wideband meta-material electromagnetic absorber structure is implemented. This adiabatic structure absorbs greater than 99 of the power over the 1.7:1 operational band at angles ranging from normal (0 degree) to near parallel (180 degree) incidence. Design, simulations, and application of the device will be presented.

Transition in discharge plasma of Hall thruster type in presence of secondary electron emissive surface

NASA Astrophysics Data System (ADS)

Schweigert, I. V.; Yadrenkin, M. A.; Fomichev, V. P.

2017-11-01

Modification of the sheath structure near the emissive plate placed in magnetized DC discharge plasma of Hall thruster type was studied in the experiment and in kinetic simulations. The plate is made from Al2O3 which has enhanced secondary electron emission yield. The energetic electrons emitted by heated cathode provide the volume ionization and the secondary electron emission from the plate. An increase of the electron beam energy leads to an increase of the secondary electron generation, which initiates the transition in sheath structure over the emissive plate.

Aerial ultrasound source with a circular vibrating plate attached to a rigid circumferential wall

NASA Astrophysics Data System (ADS)

Kuratomi, Ryo; Asami, Takuya; Miura, Hikaru

2018-07-01

We fabricate a transverse vibrating plate attached to a rigid wall integrated at the circumference of a circular vibrating plate that allows a strong sound wave field to be formed in the area encoded by the vibrating plate and rigid wall by installing a wall such as a reflective plate on the rigid wall. The design method for the circular vibrating plate attached to a rigid circumferential wall is investigated. A method of forming a strong standing wave field in an enclosed area constructed with a vibrating plate, cylindrical reflective plate, and parallel reflective plate is developed.

Neutron-induced fission cross section measurements for uranium isotopes 236U and 234U at LANSCE

NASA Astrophysics Data System (ADS)

Laptev, A. B.; Tovesson, F.; Hill, T. S.

2013-04-01

A well established program of neutron-induced fission cross section measurement at Los Alamos Neutron Science Center (LANSCE) is supporting the Fuel Cycle Research program (FC R&D). The incident neutron energy range spans from sub-thermal up to 200 MeV by combining two LANSCE facilities, the Lujan Center and the Weapons Neutron Research facility (WNR). The time-of-flight method is implemented to measure the incident neutron energy. A parallel-plate fission ionization chamber was used as a fission fragment detector. The event rate ratio between the investigated foil and a standard 235U foil is converted into a fission cross section ratio. In addition to previously measured data new measurements include 236U data which is being analyzed, and 234U data acquired in the 2011-2012 LANSCE run cycle. The new data complete the full suite of Uranium isotopes which were investigated with this experimental approach. Obtained data are presented in comparison with existing evaluations and previous data.

The HyperV 8000 μg, 50 km/s Plasma Railgun for PLX

NASA Astrophysics Data System (ADS)

Brockington, Samuel; Case, Andrew; Messer, Sarah; Wu, Linchun; Witherspoon, F. Douglas

2012-10-01

HyperV has developed a gas fed, pulsed, plasma railgun which accelerates 8000 μg of argon to 50 km/s meeting the performance requirements originally specified for the Plasma Liner Experiment (PLX). The present 2.5 cm square-bore plasma railgun forms plasma armatures from high density neutral gas, pre-ionizes it electro-thermally, and accelerates the armature with 30 cm long parallel-plate railgun electrodes driven by a pulse forming network (PFN). A high voltage, high current linear array spark-gap switch and flexible, low-inductance transmission line were designed and constructed to handle the increased current load. We will describe these systems and present initial performance data from high current operation of the plasma rail gun from spectroscopy, interferometry, and imaging systems. Measurements of momentum, pressure, magnetic field, and other optical diagnostics will also be discussed as well as plans for upcoming experimentation to increase performance even further. Work supported by USDOE under DE-FG02-05ER54810 and DE-FG02-08ER85114.

Characteristics of a normoxic polymethacrylic acid gel dosimeter for a 72-MeV proton beam

NASA Astrophysics Data System (ADS)

Bong, Jihye; Shin, Dongho; Kwon, Soo-Il

2014-01-01

The characteristics of a normoxic polymethacrylic acid gel dosimeter for a 72-MeV proton beam were evaluated. A polymer gel dosimeter was synthesized using gelatin, methacrylic acid, hydroquinone, tetrakis(hydroxymethyl) phosphonium chloride, and highly purified distilled water. The dosimeter was manufactured by placement in a polyethylene (PE) container. Irradiated dosimeters were analyzed to determine the transverse relaxation time (T2) using a 1.5-T MRI. A calibration curve was obtained as a function of the absorbed dose. A Bragg curve made by irradiating the gel with mono-energy was compared with the results for a parallel plate ionization chamber. The spread-out Bragg peak (SOBP) range and distal dose fall-off (DDF) were comparatively analyzed by comparing the irradiated gel with a spread-out Bragg peak against with the ion chamber. Lastly, the gel's usefulness as a dosimeter for therapeutic radiation quality assurance was evaluated by obtaining its practical field size, flatness, and symmetry, through comparison of the profiles of the gel and ion chamber.

High dynamic range bio-molecular ion microscopy with the Timepix detector.

PubMed

Jungmann, Julia H; MacAleese, Luke; Visser, Jan; Vrakking, Marc J J; Heeren, Ron M A

2011-10-15

Highly parallel, active pixel detectors enable novel detection capabilities for large biomolecules in time-of-flight (TOF) based mass spectrometry imaging (MSI). In this work, a 512 × 512 pixel, bare Timepix assembly combined with chevron microchannel plates (MCP) captures time-resolved images of several m/z species in a single measurement. Mass-resolved ion images from Timepix measurements of peptide and protein standards demonstrate the capability to return both mass-spectral and localization information of biologically relevant analytes from matrix-assisted laser desorption ionization (MALDI) on a commercial ion microscope. The use of a MCP-Timepix assembly delivers an increased dynamic range of several orders of magnitude. The Timepix returns defined mass spectra already at subsaturation MCP gains, which prolongs the MCP lifetime and allows the gain to be optimized for image quality. The Timepix peak resolution is only limited by the resolution of the in-pixel measurement clock. Oligomers of the protein ubiquitin were measured up to 78 kDa. © 2011 American Chemical Society

Laser-excited pulse propagation in a crystallized complex plasma

NASA Astrophysics Data System (ADS)

Nosenko, V.; Nunomura, S.; Goree, J.

2000-10-01

A complex plasma, so-called in analogy with complex fluids, is an ionized gas containing small solid particles. This medium is also called a dusty plasma. The particles acquire a large negative electric charge. In an experiment, polymer microspheres were shaken into a parallel-plate rf plasma. The particles were levitated by the electric field in the sheath above the lower electrode. The particles settled in a single horizontal layer, and were arranged in a hexagonal lattice. They were imaged using a video camera to record the particle motion. Like any crystal, this so-called ``plasma crystal'' sustains compressional sound waves, which can be launched as a pulse. By modulating an argon laser beam directed tangentially at the lattice, we launched a pulsed wave in the lattice. We evaluated the pulse shape and propagation speed, while varying the pulse power and duration. This allowed a test for dispersion and nonlinearity, as well as a test of whether the pulse has the properties of a shock.

Results on nucleon life-time from the Kolar gold field experiment

NASA Technical Reports Server (NTRS)

Krishnaswamy, M. R.; Menon, M. G. K.; Mondal, N. K.; Narasimham, V. S.; Sreekantan, B. V.; Hayashi, Y.; Ito, N.; Kawakami, S.; Miyake, S.

1985-01-01

The KGF nucleon decay experiment has been in operation since October 1980 with a 140 ton calorimetric detector at a depth of 2.3 Km underground. The detector comprises 34 layers of proportional counters arranged in an orthogonal geometry with 12 mm thick iron plates in between successive layers. The proportional counters are made up of square (10 x 10 square centimeters) iron plates of wall thickness 2.3 mm. Each of the 1600 counters is instrumented to provide data on ionization, DE/dx and arrival time. The visible energy of a particle is determined to an accuracy of approximately 20% from the ionization and range of its track. The end point ionization of a stopping track provides the direction of motion as well as the nature of the particle (mu/pi,k,p). Decay of mu is recorded with an overall efficiency of only 20% in view of the thickness of 13 g/square centimeters between successive layers.

Particle-in-cell simulations of the critical ionization velocity effect in finite size clouds

NASA Technical Reports Server (NTRS)

Moghaddam-Taaheri, E.; Lu, G.; Goertz, C. K.; Nishikawa, K. - I.

1994-01-01

The critical ionization velocity (CIV) mechanism in a finite size cloud is studied with a series of electrostatic particle-in-cell simulations. It is observed that an initial seed ionization, produced by non-CIV mechanisms, generates a cross-field ion beam which excites a modified beam-plasma instability (MBPI) with frequency in the range of the lower hybrid frequency. The excited waves accelerate electrons along the magnetic field up to the ion drift energy that exceeds the ionization energy of the neutral atoms. The heated electrons in turn enhance the ion beam by electron-neutral impact ionization, which establishes a positive feedback loop in maintaining the CIV process. It is also found that the efficiency of the CIV mechanism depends on the finite size of the gas cloud in the following ways: (1) Along the ambient magnetic field the finite size of the cloud, L (sub parallel), restricts the growth of the fastest growing mode, with a wavelength lambda (sub m parallel), of the MBPI. The parallel electron heating at wave saturation scales approximately as (L (sub parallel)/lambda (sub m parallel)) (exp 1/2); (2) Momentum coupling between the cloud and the ambient plasma via the Alfven waves occurs as a result of the finite size of the cloud in the direction perpendicular to both the ambient magnetic field and the neutral drift. This reduces exponentially with time the relative drift between the ambient plasma and the neutrals. The timescale is inversely proportional to the Alfven velocity. (3) The transvers e charge separation field across the cloud was found to result in the modulation of the beam velocity which reduces the parallel heating of electrons and increases the transverse acceleration of electrons. (4) Some energetic electrons are lost from the cloud along the magnetic field at a rate characterized by the acoustic velocity, instead of the electron thermal velocity. The loss of energetic electrons from the cloud seems to be larger in the direction of plasma drift relative to the neutrals, where the loss rate is characterized by the neutral drift velocity. It is also shown that a factor of 4 increase in the ambient plasma density, increases the CIV ionization yield by almost 2 orders of magnitude at the end of a typical run. It is concluded that a larger ambient plasma density can result in a larger CIV yield because of (1) larger seed ion production by non-CIV mechanisms, (2) smaller Alfven velocity and hence weak momentum coupling, and (3) smaller ratio of the ion beam density to the ambient ion density, and therefore a weaker modulation of the beam velocity. The simulation results are used to interpret various chemical release experiments in space.

Dual parallel mass apectrometry (LC1/MS2 and LC2/MS2) for lipid and vitamin D analysis

USDA-ARS?s Scientific Manuscript database

Atmospheric pressure chemical ionization (APCI) mass spectrometry (MS) and electrospray ionization (ESI) MS are complementary techniques that provide different types of information for lipids such as triacylglycerols, phospholipids, and fat-soluble vitamins. Since no one technique is by itself idea...

Dual Parallel Mass Spectrometry (LC1/MS2 and LC2/MS2) for Lipid and Vitamin D Analysis

USDA-ARS?s Scientific Manuscript database

Atmospheric pressure chemical ionization (APCI) mass spectrometry (MS) and electrospray ionization (ESI) MS are complementary techniques that provide different types of information for lipids such as triacylglycerols (TAGs), phospholipids, and fat-soluble vitamins. Since no one technique is by itsel...

Characterization of weakly ionized argon flows for radio blackout mitigation experiments

NASA Astrophysics Data System (ADS)

Steffens, L.; Koch, U.; Esser, B.; Gülhan, A.

2017-06-01

For reproducing the so-called E × B communication blackout mitigation scheme inside the L2K arc heated facility of the DLR in weakly ionized argon §ows, a §at plate model has been equipped with a superconducting magnet, electrodes, and a setup comprising microwave plasma transmission spectroscopy (MPTS). A thorough characterization of the weakly ionized argon §ow has been performed including the use of microwave interferometry (MWI), Langmuir probe measurements, Pitot probe pro¦les, and spectroscopic methods like diode laser absorption spectroscopy (DLAS) and emission spectroscopy.

Plasma deposition and surface modification techniques for wear resistance

NASA Technical Reports Server (NTRS)

Spalvins, T.

1982-01-01

The ion-assisted or plasma coating technology is discussed as it applies to the deposition of hard, wear resistant refractory compound films. Of the many sputtering and ion plating modes and configurations the reactive magnetron sputtering and the reactive triode ion plating techniques are the preferred ones to deposit wear resistant coatings for tribological applications. Both of these techniques incorporate additional means to enhance the ionization efficiency and chemical reaction to precision tailor desirable tribological characteristics. Interrelationships between film formation, structure, and ribological properties are strictly controlled by the deposition parameters and the substrate condition. The enhanced ionization contributes to the excellent adherence and coherence, reduced internal stresses and improved structural growth to form dense, cohesive, equiaxed grain structure for improved wear resistance and control.

Parallel DSMC Solution of Three-Dimensional Flow Over a Finite Flat Plate

NASA Technical Reports Server (NTRS)

Nance, Robert P.; Wilmoth, Richard G.; Moon, Bongki; Hassan, H. A.; Saltz, Joel

1994-01-01

This paper describes a parallel implementation of the direct simulation Monte Carlo (DSMC) method. Runtime library support is used for scheduling and execution of communication between nodes, and domain decomposition is performed dynamically to maintain a good load balance. Performance tests are conducted using the code to evaluate various remapping and remapping-interval policies, and it is shown that a one-dimensional chain-partitioning method works best for the problems considered. The parallel code is then used to simulate the Mach 20 nitrogen flow over a finite-thickness flat plate. It is shown that the parallel algorithm produces results which compare well with experimental data. Moreover, it yields significantly faster execution times than the scalar code, as well as very good load-balance characteristics.

Vectorization and parallelization of the finite strip method for dynamic Mindlin plate problems

NASA Technical Reports Server (NTRS)

Chen, Hsin-Chu; He, Ai-Fang

1993-01-01

The finite strip method is a semi-analytical finite element process which allows for a discrete analysis of certain types of physical problems by discretizing the domain of the problem into finite strips. This method decomposes a single large problem into m smaller independent subproblems when m harmonic functions are employed, thus yielding natural parallelism at a very high level. In this paper we address vectorization and parallelization strategies for the dynamic analysis of simply-supported Mindlin plate bending problems and show how to prevent potential conflicts in memory access during the assemblage process. The vector and parallel implementations of this method and the performance results of a test problem under scalar, vector, and vector-concurrent execution modes on the Alliant FX/80 are also presented.

Analysis of the longitudinal space charge impedance of a round uniform beam inside parallel plates and rectangular chambers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, L.; Li, Y.

2015-02-03

This paper analyzes the longitudinal space charge impedances of a round uniform beam inside a rectangular and parallel plate chambers using the image charge method. This analysis is valid for arbitrary wavelengths, and the calculations converge rapidly. The research shows that only a few of the image beams are needed to obtain a relative error less than 0.1%. The beam offset effect is also discussed in the analysis.

Exploratory Experiments in the Tribological Behavior of Engineering Surfaces with Nano-Coating Using a Tribo-Rheometer

DTIC Science & Technology

2008-05-30

Tribological behavior and graphitization of carbon nanotubes grown on 440C stainless steel . Tribo. Lett., 19(2):119-125, 2005. D-2 ...with a stainless steel parallel plate configuration as shown in figure 1. Due to the radial variation of the local shear stress T in the parallel...using a force transducer that is mounted below the surface. B-1 Exploded View Stainless Steel Plate Lower Fixture Microscale View Figure 1:

A bioconvection model for a squeezing flow of nanofluid between parallel plates in the presence of gyrotactic microorganisms

NASA Astrophysics Data System (ADS)

Bin-Mohsin, Bandar; Ahmed, Naveed; Adnan; Khan, Umar; Tauseef Mohyud-Din, Syed

2017-04-01

This article deals with the bioconvection flow in a parallel-plate channel. The plates are parallel and the flowing fluid is saturated with nanoparticles, and water is considered as a base fluid because microorganisms can survive only in water. A highly nonlinear and coupled system of partial differential equations presenting the model of bioconvection flow between parallel plates is reduced to a nonlinear and coupled system (nondimensional bioconvection flow model) of ordinary differential equations with the help of feasible nondimensional variables. In order to find the convergent solution of the system, a semi-analytical technique is utilized called variation of parameters method (VPM). Numerical solution is also computed and the Runge-Kutta scheme of fourth order is employed for this purpose. Comparison between these solutions has been made on the domain of interest and found to be in excellent agreement. Also, influence of various parameters has been discussed for the nondimensional velocity, temperature, concentration and density of the motile microorganisms both for suction and injection cases. Almost inconsequential influence of thermophoretic and Brownian motion parameters on the temperature field is observed. An interesting variation are inspected for the density of the motile microorganisms due to the varying bioconvection parameter in suction and injection cases. At the end, we make some concluding remarks in the light of this article.

Intensity and Energy Level Analysis of the Vacuum Ultraviolet Spectrum of Four Times Ionize Nickel (Ni V)

NASA Astrophysics Data System (ADS)

Ward, Jacob Wolfgang; Nave, Gillian

2016-01-01

Recent measurements of four times ionized iron and nickel (Fe V & Ni V) wavelengths in the vacuum ultraviolet (VUV) have been taken using the National Institute for Standards and Technology (NIST) Normal Incidence Vacuum Spectrograph (NIVS) with a sliding spark light source with invar electrodes. The wavelengths observed in those measurements make use of high resolution photographic plates with the majority of observed lines having uncertainties of approximately 3mÅ. In addition to observations made with photographic plates, the same wavelength region was observed with phosphor image plates, which have been demonstrated to be accurate as a method of intensity calibration when used with a deuterium light source. This work will evaluate the use of phosphor image plates and deuterium lamps as an intensity calibration method for the Ni V spectrum in the 1200-1600Å region of the VUV. Additionally, by pairing the observed wavelengths of Ni V with accurate line intensities, it is possible to create an energy level optimization for Ni V providing high accuracy Ritz wavelengths. This process has previously been applied to Fe V and produced Ritz wavelengths that agreed with the above experimental observations.

Channel plate for DNA sequencing

DOEpatents

Douthart, R.J.; Crowell, S.L.

1998-01-13

This invention is a channel plate that facilitates data compaction in DNA sequencing. The channel plate has a length, a width and a thickness, and further has a plurality of channels that are parallel. Each channel has a depth partially through the thickness of the channel plate. Additionally an interface edge permits electrical communication across an interface through a buffer to a deposition membrane surface. 15 figs.

Performance-related test for asphalt emulsions.

DOT National Transportation Integrated Search

2004-10-01

Yield stress was investigated as a potential quality control parameter for asphalt emulsions. Viscometric data were determined using the concentric cylinder, parallel plate, and cone and plate geometries with rotational rheometers. We also investigat...

Collimator of multiple plates with axially aligned identical random arrays of apertures

NASA Technical Reports Server (NTRS)

Hoover, R. B.; Underwood, J. H. (Inventor)

1973-01-01

A collimator is disclosed for examining the spatial location of distant sources of radiation and for imaging by projection, small, near sources of radiation. The collimator consists of a plurality of plates, all of which are pierced with an identical random array of apertures. The plates are mounted perpendicular to a common axis, with like apertures on consecutive plates axially aligned so as to form radiation channels parallel to the common axis. For near sources, the collimator is interposed between the source and a radiation detector and is translated perpendicular to the common axis so as to project radiation traveling parallel to the common axis incident to the detector. For far sources the collimator is scanned by rotating it in elevation and azimuth with a detector to determine the angular distribution of the radiation from the source.

Large-scale trench-perpendicular mantle flow beneath northern Chile

NASA Astrophysics Data System (ADS)

Reiss, M. C.; Rumpker, G.; Woelbern, I.

2017-12-01

We investigate the anisotropic properties of the forearc region of the central Andean margin by analyzing shear-wave splitting from teleseismic and local earthquakes from the Nazca slab. The data stems from the Integrated Plate boundary Observatory Chile (IPOC) located in northern Chile, covering an approximately 120 km wide coastal strip between 17°-25° S with an average station spacing of 60 km. With partly over ten years of data, this data set is uniquely suited to address the long-standing debate about the mantle flow field at the South American margin and in particular whether the flow field beneath the slab is parallel or perpendicular to the trench. Our measurements yield two distinct anisotropic layers. The teleseismic measurements show a change of fast polarizations directions from North to South along the trench ranging from parallel to subparallel to the absolute plate motion and, given the geometry of absolute plate motion and strike of the trench, mostly perpendicular to the trench. Shear-wave splitting from local earthquakes shows fast polarizations roughly aligned trench-parallel but exhibit short-scale variations which are indicative of a relatively shallow source. Comparisons between fast polarization directions and the strike of the local fault systems yield a good agreement. We use forward modelling to test the influence of the upper layer on the teleseismic measurements. We show that the observed variations of teleseismic measurements along the trench are caused by the anisotropy in the upper layer. Accordingly, the mantle layer is best characterized by an anisotropic fast axes parallel to the absolute plate motion which is roughly trench-perpendicular. This anisotropy is likely caused by a combination of crystallographic preferred orientation of the mantle mineral olivine as fossilized anisotropy in the slab and entrained flow beneath the slab. We interpret the upper anisotropic layer to be confined to the crust of the overriding continental plate. This is explained by the shape-preferred orientation of micro-cracks in relation to local fault zones which are oriented parallel the overall strike of the Andean range. Our results do not provide any evidence for a significant contribution of trench-parallel mantle flow beneath the subducting slab to the measurements.

Build-up and surface dose measurements on phantoms using micro-MOSFET in 6 and 10 MV x-ray beams and comparisons with Monte Carlo calculations.

PubMed

Xiang, Hong F; Song, Jun S; Chin, David W H; Cormack, Robert A; Tishler, Roy B; Makrigiorgos, G Mike; Court, Laurence E; Chin, Lee M

2007-04-01

This work is intended to investigate the application and accuracy of micro-MOSFET for superficial dose measurement under clinically used MV x-ray beams. Dose response of micro-MOSFET in the build-up region and on surface under MV x-ray beams were measured and compared to Monte Carlo calculations. First, percentage-depth-doses were measured with micro-MOSFET under 6 and 10 MV beams of normal incidence onto a flat solid water phantom. Micro-MOSFET data were compared with the measurements from a parallel plate ionization chamber and Monte Carlo dose calculation in the build-up region. Then, percentage-depth-doses were measured for oblique beams at 0 degrees-80 degrees onto the flat solid water phantom with micro-MOSFET placed at depths of 2 cm, 1 cm, and 2 mm below the surface. Measurements were compared to Monte Carlo calculations under these settings. Finally, measurements were performed with micro-MOSFET embedded in the first 1 mm layer of bolus placed on a flat phantom and a curved phantom of semi-cylindrical shape. Results were compared to superficial dose calculated from Monte Carlo for a 2 mm thin layer that extends from the surface to a depth of 2 mm. Results were (1) Comparison of measurements with MC calculation in the build-up region showed that micro-MOSFET has a water-equivalence thickness (WET) of 0.87 mm for 6 MV beam and 0.99 mm for 10 MV beam from the flat side, and a WET of 0.72 mm for 6 MV beam and 0.76 mm for 10 MV beam from the epoxy side. (2) For normal beam incidences, percentage depth dose agree within 3%-5% among micro-MOSFET measurements, parallel-plate ionization chamber measurements, and MC calculations. (3) For oblique incidence on the flat phantom with micro-MOSFET placed at depths of 2 cm, 1 cm, and 2 mm, measurements were consistent with MC calculations within a typical uncertainty of 3%-5%. (4) For oblique incidence on the flat phantom and a curved-surface phantom, measurements with micro-MOSFET placed at 1.0 mm agrees with the MC calculation within 6%, including uncertainties of micro-MOSFET measurements of 2%-3% (1 standard deviation), MOSFET angular dependence of 3.0%-3.5%, and 1%-2% systematical error due to phantom setup geometry asymmetry. Micro-MOSFET can be used for skin dose measurements in 6 and 10 MV beams with an estimated accuracy of +/- 6%.

Superfocusing terahertz waves below lambda/250 using plasmonic parallel-plate waveguides.

PubMed

Zhan, Hui; Mendis, Rajind; Mittleman, Daniel M

2010-04-26

We experimentally demonstrate complete two-dimensional (2-D) confinement of terahertz (THz) energy in finite-width parallel-plate waveguides, defying conventional wisdom in the century-old field of microwave waveguide technology. We find that the degree of energy confinement increases exponentially with decreasing plate separation. We propose that this 2-D confinement is mediated by the mutual coupling of plasmonic edge modes, analogous to that observed in slot waveguides at optical wavelengths. By adiabatically tapering the width and the separation, we focus THz waves down to a size of 10 microm (approximately lambda/260) by 18 microm ( approximately lambda/145), which corresponds to a mode area of only 2.6 x 10(-5) lambda(2).

Air flow in the boundary layer near a plate

NASA Technical Reports Server (NTRS)

Dryden, Hugh L

1937-01-01

The published data on the distribution of speed near a thin flat plate with sharp leading edge placed parallel to the flow (skin friction plate) are reviewed and the results of some additional measurements are described. The purpose of the experiments was to study the basic phenomena of boundary-layer flow under simple conditions.

Evaluation of resolution and periodic errors of a flatbed scanner used for digitizing spectroscopic photographic plates

PubMed Central

Wyatt, Madison; Nave, Gillian

2017-01-01

We evaluated the use of a commercial flatbed scanner for digitizing photographic plates used for spectroscopy. The scanner has a bed size of 420 mm by 310 mm and a pixel size of about 0.0106 mm. Our tests show that the closest line pairs that can be resolved with the scanner are 0.024 mm apart, only slightly larger than the Nyquist resolution of 0.021 mm expected by the 0.0106 mm pixel size. We measured periodic errors in the scanner using both a calibrated length scale and a photographic plate. We find no noticeable periodic errors in the direction parallel to the linear detector in the scanner, but errors with an amplitude of 0.03 mm to 0.05 mm in the direction perpendicular to the detector. We conclude that large periodic errors in measurements of spectroscopic plates using flatbed scanners can be eliminated by scanning the plates with the dispersion direction parallel to the linear detector by placing the plate along the short side of the scanner. PMID:28463262

Three-dimensional analytical solution for the instability of a parallel array of mutually attracting identical simply supported piezoelectric microplates

NASA Astrophysics Data System (ADS)

Liu, Lei; Wang, Xu

2017-12-01

Three-dimensional analytical solutions are derived for the structural instability of a parallel array of mutually attracting identical simply supported orthotropic piezoelectric rectangular microplates by means of a linear perturbation analysis. The two surfaces of each plate can be either insulating or conducting. By considering the fact that the shear stresses and the normal electric displacement (or electric potential) are zero on the two surfaces of each plate, a 2 × 2 transfer matrix for a plate can be obtained directly from the 8 × 8 fundamental piezoelectricity matrix without resolving the original Stroh eigenrelation. The critical interaction coefficient can be determined by solving the resulting generalized eigenvalue problem for the piezoelectric plate array. Also considered in our analysis is the in-plane uniform edge compression acting on the four sides of each piezoelectric plate. Our results indicate that the stabilizing influence of the piezoelectric effect on the structural instability is unignorable; the edge compression always plays a destabilizing role in the structural instability of the plate array with interactions.

The Iceland Plate Boundary Zone: Propagating Rifts, Migrating Transforms, and Rift-Parallel Strike-Slip Faults

NASA Astrophysics Data System (ADS)

Karson, J. A.

2017-11-01

Unlike most of the Mid-Atlantic Ridge, the North America/Eurasia plate boundary in Iceland lies above sea level where magmatic and tectonic processes can be directly investigated in subaerial exposures. Accordingly, geologic processes in Iceland have long been recognized as possible analogs for seafloor spreading in the submerged parts of the mid-ocean ridge system. Combining existing and new data from across Iceland provides an integrated view of this active, mostly subaerial plate boundary. The broad Iceland plate boundary zone includes segmented rift zones linked by transform fault zones. Rift propagation and transform fault migration away from the Iceland hotspot rearrange the plate boundary configuration resulting in widespread deformation of older crust and reactivation of spreading-related structures. Rift propagation results in block rotations that are accommodated by widespread, rift-parallel, strike-slip faulting. The geometry and kinematics of faulting in Iceland may have implications for spreading processes elsewhere on the mid-ocean ridge system where rift propagation and transform migration occur.

Parallel-plate transmission line type of EMP simulators: Systematic review and recommendations

NASA Astrophysics Data System (ADS)

Giri, D. V.; Liu, T. K.; Tesche, F. M.; King, R. W. P.

1980-05-01

This report presents various aspects of the two-parallel-plate transmission line type of EMP simulator. Much of the work is the result of research efforts conducted during the last two decades at the Air Force Weapons Laboratory, and in industries/universities as well. The principal features of individual simulator components are discussed. The report also emphasizes that it is imperative to hybridize our understanding of individual components so that we can draw meaningful conclusions of simulator performance as a whole.

Scalar Casimir densities and forces for parallel plates in cosmic string spacetime

NASA Astrophysics Data System (ADS)

Bezerra de Mello, E. R.; Saharian, A. A.; Abajyan, S. V.

2018-04-01

We analyze the Green function, the Casimir densities and forces associated with a massive scalar quantum field confined between two parallel plates in a higher dimensional cosmic string spacetime. The plates are placed orthogonal to the string, and the field obeys the Robin boundary conditions on them. The boundary-induced contributions are explicitly extracted in the vacuum expectation values (VEVs) of the field squared and of the energy-momentum tensor for both the single plate and two plates geometries. The VEV of the energy-momentum tensor, in additional to the diagonal components, contains an off diagonal component corresponding to the shear stress. The latter vanishes on the plates in special cases of Dirichlet and Neumann boundary conditions. For points outside the string core the topological contributions in the VEVs are finite on the plates. Near the string the VEVs are dominated by the boundary-free part, whereas at large distances the boundary-induced contributions dominate. Due to the nonzero off diagonal component of the vacuum energy-momentum tensor, in addition to the normal component, the Casimir forces have nonzero component parallel to the boundary (shear force). Unlike the problem on the Minkowski bulk, the normal forces acting on the separate plates, in general, do not coincide if the corresponding Robin coefficients are different. Another difference is that in the presence of the cosmic string the Casimir forces for Dirichlet and Neumann boundary conditions differ. For Dirichlet boundary condition the normal Casimir force does not depend on the curvature coupling parameter. This is not the case for other boundary conditions. A new qualitative feature induced by the cosmic string is the appearance of the shear stress acting on the plates. The corresponding force is directed along the radial coordinate and vanishes for Dirichlet and Neumann boundary conditions. Depending on the parameters of the problem, the radial component of the shear force can be either positive or negative.

Transform push, oblique subduction resistance, and intraplate stress of the Juan de Fuca plate

USGS Publications Warehouse

Wang, K.; He, J.; Davis, E.E.

1997-01-01

The Juan de Fuca plate is a small oceanic plate between the Pacific and North America plates. In the southernmost region, referred to as the Gorda deformation zone, the maximum compressive stress a, constrained by earthquake focal mechanisms is N-S. Off Oregon, and possibly off Washington, NW trending left-lateral faults cutting the Juan de Fuca plate indicate a a, in a NE-SW to E-W direction. The magnitude of differential stress increases from north to south; this is inferred from the plastic yielding and distribution of earthquakes throughout the Gorda deformation zone. To understand how tectonic forces determine the stress field of the Juan de Fuca plate, we have modeled the intraplate stress using both elastic and elastic-perfectly plastic plane-stress finite element models. We conclude that the right-lateral shear motion of the Pacific and North America plates is primarily responsible for the stress pattern of the Juan de Fuca plate. The most important roles are played by a compressional force normal to the Mendocino transform fault, a result of the northward push by the Pacific plate and a horizontal resistance operating against the northward, or margin-parallel, component of oblique subduction. Margin-parallel subduction resistance results in large N-S compression in the Gorda deformation zone because the force is integrated over the full length of the Cascadia subduction zone. The Mendocino transform fault serves as a strong buttress that is very weak in shear but capable of transmitting large strike-normal compressive stresses. Internal failure of the Gorda deformation zone potentially places limits on the magnitude of the fault-normal stresses being transmitted and correspondingly on the magnitude of strike-parallel subduction resistance. Transform faults and oblique subduction zones in other parts of the world can be expected to transmit and create stresses in the same manner. Copyright 1997 by the American Geophysical Union.

CRIT II electric, magnetic, and density measurements within an ionizing neutral stream

NASA Technical Reports Server (NTRS)

Swenson, C. M.; Kelley, M. C.; Primdahl, F.; Baker, K. D.

1990-01-01

Measurements from rocket-borne sensors inside a high-velocity neutral barium beam show a-factor-of-six increase in plasma density in a moving ionizing front. This region was colocated with intense fluctuating electric fields at frequencies well under the lower hybrid frequency for a barium plasma. Large quasi-dc electric and magnetic field fluctuations were also detected with a large component of the current and the electric field parallel to B(0). An Alfven wave with a finite electric field component parallel to the geomagnetic field was observed to propagate along B(0), where it was detected by an instrumented subpayload.

A new parallel plate shear cell for in situ real-space measurements of complex fluids under shear flow.

PubMed

Wu, Yu Ling; Brand, Joost H J; van Gemert, Josephus L A; Verkerk, Jaap; Wisman, Hans; van Blaaderen, Alfons; Imhof, Arnout

2007-10-01

We developed and tested a parallel plate shear cell that can be mounted on top of an inverted microscope to perform confocal real-space measurements on complex fluids under shear. To follow structural changes in time, a plane of zero velocity is created by letting the plates move in opposite directions. The location of this plane is varied by changing the relative velocities of the plates. The gap width is variable between 20 and 200 microm with parallelism better than 1 microm. Such a small gap width enables us to examine the total sample thickness using high numerical aperture objective lenses. The achieved shear rates cover the range of 0.02-10(3) s(-1). This shear cell can apply an oscillatory shear with adjustable amplitude and frequency. The maximum travel of each plate equals 1 cm, so that strains up to 500 can be applied. For most complex fluids, an oscillatory shear with such a large amplitude can be regarded as a continuous shear. We measured the flow profile of a suspension of silica colloids in this shear cell. It was linear except for a small deviation caused by sedimentation. To demonstrate the excellent performance and capabilities of this new setup we examined shear induced crystallization and melting of concentrated suspensions of 1 microm diameter silica colloids.

Energetic ion, atom, and molecule reactions and excitation in low-current H2 discharges: H(alpha) Doppler profiles.

PubMed

Petrović, Z Lj; Phelps, A V

2009-12-01

Absolute spectral emissivities for Doppler broadened H(alpha) profiles are measured and compared with predictions of energetic hydrogen ion, atom, and molecule behavior in low-current electrical discharges in H2 at very high electric field E to gas density N ratios E/N and low values of Nd , where d is the parallel-plate electrode separation. These observations reflect the energy and angular distributions for the excited atoms and quantitatively test features of multiple-scattering kinetic models in weakly ionized hydrogen in the presence of an electric field that are not tested by the spatial distributions of H(alpha) emission. Absolute spectral intensities agree well with predictions. Asymmetries in Doppler profiles observed parallel to the electric field at 4

SLIT ADJUSTMENT CLAMP

DOEpatents

McKenzie, K.R.

1959-07-01

An electrode support which permits accurate alignment and adjustment of the electrode in a plurality of planes and about a plurality of axes in a calutron is described. The support will align the slits in the electrode with the slits of an ionizing chamber so as to provide for the egress of ions. The support comprises an insulator, a leveling plate carried by the insulator and having diametrically opposed attaching screws screwed to the plate and the insulator and diametrically opposed adjusting screws for bearing against the insulator, and an electrode associated with the plate for adjustment therewith.

Parallelism measurement for base plate of standard artifact with multiple tactile approaches

NASA Astrophysics Data System (ADS)

Ye, Xiuling; Zhao, Yan; Wang, Yiwen; Wang, Zhong; Fu, Luhua; Liu, Changjie

2018-01-01

Nowadays, as workpieces become more precise and more specialized which results in more sophisticated structures and higher accuracy for the artifacts, higher requirements have been put forward for measuring accuracy and measuring methods. As an important method to obtain the size of workpieces, coordinate measuring machine (CMM) has been widely used in many industries. In order to achieve the calibration of a self-developed CMM, it is found that the parallelism of the base plate used for fixing the standard artifact is an important factor which affects the measurement accuracy in the process of studying self-made high-precision standard artifact. And aimed to measure the parallelism of the base plate, by using the existing high-precision CMM, gauge blocks, dial gauge and marble platform with the tactile approach, three methods for parallelism measurement of workpieces are employed, and comparisons are made within the measurement results. The results of experiments show that the final accuracy of all the three methods is able to reach micron level and meets the measurement requirements. Simultaneously, these three approaches are suitable for different measurement conditions which provide a basis for rapid and high-precision measurement under different equipment conditions.

Mini-Fragment Fixation Is Equivalent to Bicortical Screw Fixation for Horizontal Medial Malleolus Fractures.

PubMed

Wegner, Adam M; Wolinsky, Philip R; Robbins, Michael A; Garcia, Tanya C; Amanatullah, Derek F

2018-05-01

Horizontal fractures of the medial malleolus occur through application of valgus or abduction force through the ankle that creates a tension failure of the medial malleolus. The authors hypothesize that mini-fragment T-plates may offer improved fixation, but the optimal fixation construct for these fractures remains unclear. Forty synthetic distal tibiae with identical osteotomies were randomized into 4 fixation constructs: (1) two parallel unicortical cancellous screws; (2) two parallel bicortical cortical screws; (3) a contoured mini-fragment T-plate with 2 unicortical screws in the fragment and 2 bicortical screws in the shaft; and (4) a contoured mini-fragment T-plate with 2 bicortical screws in the fragment and 2 unicortical screws in the shaft. Specimens were subjected to offset axial tension loading on a servohydraulic testing system and tracked using high-resolution video. Failure was defined as 2 mm of articular displacement. Analysis of variance followed by a Tukey-Kramer post hoc test was used to assess for differences between groups, with significance defined as P<.05. The mean stiffness (±SD) values of both mini-fragment T-plate constructs (239±83 N/mm and 190±37 N/mm) and the bicortical screw construct (240±17 N/mm) were not statistically different. The mean stiffness values of both mini-fragment T-plate constructs and the bicortical screw construct were higher than that of a parallel unicortical screw construct (102±20 N/mm). Contoured T-plate constructs provide stiffer initial fixation than a unicortical cancellous screw construct. The T-plate is biomechanically equivalent to a bicortical screw construct, but may be superior in capturing small fragments of bone. [Orthopedics. 2018; 41(3):e395-e399.]. Copyright 2018, SLACK Incorporated.

Sterilization of Escherichia coli O157:H7 using micro corona ionizer.

PubMed

Chua, Beelee; Son, Ahjeong

2014-06-01

We demonstrated in vitro sterilization of Escherichia coli O157:H7 bacteria on agar by a pin-between-planes micro corona ionizer. The gap between the pin and the grid was ~1.1 mm, the length of the grid was ~2.1 mm and the height was ~1.0 mm. The effective pin radius and discharge length were both approximated to be 200 μm. Ozone generation rates of ~2.3 × 10(-3) mg/s, ~2.7 × 10(-3) mg/s and ~3.5 × 10(-3) mg/s at 1,500 V were calculated for relative humidity (RH) of 35 %, 25 % and 10 % respectively. Analytical ozone generation rate increases as RH decreases and it is consistent with experimental observations. Using target and control petri dishes with E. coli plated agar, the sterilization capability of the micro corona ionizer at 37 °C for 24 h was evaluated. A ~60 % reduction in bacterial colony was shown with plate counting and its kill radius could be tuned from ~ 20 mm to ~5 mm by reducing the duty cycle from 100 % to 50 % with 30 min pulse width. The results suggested that the micro corona ionizer might be suitable as a tunable ozone source in wound dressing for chronic wound management.

MEMS fabrication and frequency sweep for suspending beam and plate electrode in electrostatic capacitor

NASA Astrophysics Data System (ADS)

Zhu, Jianxiong; Song, Weixing

2018-01-01

We report a MEMS fabrication and frequency sweep for a high-order mode suspending beam and plate layer in electrostatic micro-gap semiconductor capacitor. This suspended beam and plate was designed with silicon oxide (SiO2) film which was fabricated using bulk silicon micromachining technology on both side of a silicon substrate. The designed semiconductor capacitors were driven by a bias direct current (DC) and a sweep frequency alternative current (AC) in a room temperature for an electrical response test. Finite element calculating software was used to evaluate the deformation mode around its high-order response frequency. Compared a single capacitor with a high-order response frequency (0.42 MHz) and a 1 × 2 array parallel capacitor, we found that the 1 × 2 array parallel capacitor had a broader high-order response range. And it concluded that a DC bias voltage can be used to modulate a high-order response frequency for both a single and 1 × 2 array parallel capacitors.

A seismic reflection image for the base of a tectonic plate.

PubMed

Stern, T A; Henrys, S A; Okaya, D; Louie, J N; Savage, M K; Lamb, S; Sato, H; Sutherland, R; Iwasaki, T

2015-02-05

Plate tectonics successfully describes the surface of Earth as a mosaic of moving lithospheric plates. But it is not clear what happens at the base of the plates, the lithosphere-asthenosphere boundary (LAB). The LAB has been well imaged with converted teleseismic waves, whose 10-40-kilometre wavelength controls the structural resolution. Here we use explosion-generated seismic waves (of about 0.5-kilometre wavelength) to form a high-resolution image for the base of an oceanic plate that is subducting beneath North Island, New Zealand. Our 80-kilometre-wide image is based on P-wave reflections and shows an approximately 15° dipping, abrupt, seismic wave-speed transition (less than 1 kilometre thick) at a depth of about 100 kilometres. The boundary is parallel to the top of the plate and seismic attributes indicate a P-wave speed decrease of at least 8 ± 3 per cent across it. A parallel reflection event approximately 10 kilometres deeper shows that the decrease in P-wave speed is confined to a channel at the base of the plate, which we interpret as a sheared zone of ponded partial melts or volatiles. This is independent, high-resolution evidence for a low-viscosity channel at the LAB that decouples plates from mantle flow beneath, and allows plate tectonics to work.

Determination of crack depth in aluminum using eddy currents and GMR sensors

NASA Astrophysics Data System (ADS)

Lopes Ribeiro, A.; Pasadas, D.; Ramos, H. G.; Rocha, T.

2015-03-01

In this paper we use eddy currents to determine the depth of linear cracks in aluminum plates. A constant field probe is used to generate the spatially uniform excitation field and a single axis giant magneto-resistor (GMR) sensor is used to measure the eddy currents magnetic field. Different depths were machined in one aluminum plate with 4 mm of thickness. By scanning those cracks the magnetic field components parallel and perpendicular to the crack's line were measured when the eddy currents were launched perpendicularly to the crack's line. To characterize one crack in a plate of a given thickness and material, the experimental procedure was defined. The plate surface is scanned to detect and locate one crack. The acquired data enables the determination of the crack's length and orientation. A second scanning is performed with the excitation current perpendicular to the crack and the GMR sensing axis perpendicular and parallel to the crack's line.

TU-D-201-03: Results of a Survey On the Implementation of the TG-51 Protocol and Associated Addendum On Reference Dosimetry of External Beams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, G; Muir, B; Culberson, W

Purpose: The working group on the review and extension of the TG-51 protocol (WGTG51) collected data from American Association of Physicists in Medicine (AAPM) members with respect to their current TG-51 and associated addendum usage in the interest of considering future protocol addenda and guidance on reference dosimetry best practices. This study reports an overview of this survey on dosimetry of external beams. Methods: Fourteen survey questions were developed by WGTG51 and released in November 2015. The questions collected information on reference dosimetry, beam quality specification, and ancillary calibration equipment. Results: Of the 190 submissions completed worldwide (U.S. 70%), 83%more » were AAPM members. Of the respondents, 33.5% implemented the TG-51 addendum, with the maximum calibration difference for any photon beam, with respect to the original TG-51 protocol, being <1% for 97.4% of responses. One major finding is that 81.8% of respondents used the same cylindrical ionization chamber for photon and electron dosimetry, implying that many clinics are foregoing the use of parallel-plate chambers. Other evidence suggests equivalent dosimetric results can be obtained with both cylindrical and parallel-plate chambers in electron beams. This, combined with users comfort with cylindrical chambers for electrons will likely impact recommendations put forward in an upcoming electron beam addendum to the TG-51 protocol. Data collected on ancillary equipment showed 58.2% (45.0%) of the thermometers (barometers) in use for beam calibration had NIST traceable calibration certificates, but 48.4% (42.7%) were never recalibrated. Conclusion: This survey provides a snapshot of TG-51 external beam reference dosimetry practice in radiotherapy centers. Findings demonstrate the rapid take-up of the TG-51 photon beam addendum and raise issues for the WGTG51 to focus on going forward, including guidelines on ancillary equipment and the choice of chamber for electron beam dosimetry.« less

SU-G-201-05: Comparison of Different Methods for Output Verification of Eleckta Nucletron’s Valencia Skin Applicators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barrett, J; Yudelev, M

2016-06-15

Purpose: The provided output factors for Elekta Nucletron’s skin applicators are based on Monte Carlo simulations. These outputs have not been independently verified, and there is no recognized method for output verification of the vendor’s applicators. The purpose of this work is to validate the outputs provided by the vendor experimentally. Methods: Using a Flexitron Ir-192 HDR unit, three experimental methods were employed to determine dose with the 30 mm diameter Valencia applicator: first a gradient method using extrapolation ionization chamber (Far West Technology, EIC-1) measurements in solid water phantom at 3 mm SCD was used. The dose was derivedmore » based on first principles. Secondly a combination of a parallel plate chamber (Exradin A-10) and the EIC-1 was used to determine air kerma at 3 mm SCD. The air kerma was converted to dose to water in line with TG-61 formalism by using a muen ratio and a scatter factor measured with the skin applicators. Similarly a combination of the A-10 parallel plate chamber and gafchromic film (EBT 3) was also used. The Nk factor for the A-10 chamber was obtained through linear interpolation between ADCL supplied Nk factors for Cs-137 and M250. Results: EIC-1 measurements in solid water defined the outputs factor at 3 mm as 0.1343 cGy/U hr. The combination of A-10/ EIC-1 and A-10/EBT3 lead to output factors of 0.1383 and 0.1568 cGy/U hr, respectively. For comparison the output recommended by the vendor is 0.1659 cGy/U hr. Conclusion: All determined dose rates were lower than the vendor supplied values. The observed discrepancy between extrapolation chamber and film methods can be ascribed to extracameral gradient effects that may not be fully accounted for by the former method.« less

Experimental and Numerical Analysis of Electric Currents and Electromagnetic Blunting of Cracks in Thin Plates

DTIC Science & Technology

1984-12-01

currents are assumed to flow parallel to midsurface of the plate. 6. The normal component of the induced magnetic field does not vary across the...is coincident with the midsurface of the plate. The relationship between the two coordinates is given by: X = x(a, B) ^ y = y(c’, e) Z

Light refraction in sapphire plates with a variable angle of crystal optical axis to the surface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vetrov, V. N., E-mail: vasvetrov@mail.ru; Ignatenkov, B. A.

2013-05-15

The modification of sapphire by inhomogeneous plastic deformation makes it possible to obtain plates with a variable angle of inclination of the crystal optical axis to the plate surface. The refraction of light in this plate at perpendicular and oblique incidence of a parallel beam of rays is considered. The algorithm of calculating the refractive index of extraordinary ray and the birefringence is proposed.

Preparation of on-plate immobilized metal ion affinity chromatography platform via dopamine chemistry for highly selective isolation of phosphopeptides with matrix assisted laser desorption/ionization mass spectrometry analysis.

PubMed

Shi, Chenyi; Lin, Qinrui; Deng, Chunhui

2015-04-01

In this study, a novel on-plate IMAC technique was developed for highly selective enrichment and isolation of phosphopeptides with high-throughput MALDI-TOF-MS analysis. At first, a MALDI plate was coated with polydopamine (PDA), and then Ti(4+) was immobilized on the PDA-coated plate. The obtained IMAC plate was successfully applied to the highly selective enrichment and isolation of phosphopeptides in protein digests and human serum. Because of no loss of samples, the on-plate IMAC platform exhibits excellent selectivity and sensitivity in the selective enrichment and isolation of phosphopeptides, which provides a potential technique for high selectivity in the detection of low-abundance phosphopeptides in biological samples. Copyright © 2015 Elsevier B.V. All rights reserved.

Performance characteristics of mobile MOSFET dosimeter for kilovoltage X-rays used in image guided radiotherapy.

PubMed

Kumar, A Sathish; Singh, I Rabi Raja; Sharma, S D; Ravindran, B Paul

2015-01-01

The main objective of this study was to investigate the characteristics of metal oxide semiconductor field effect transistor (MOSFET) dosimeter for kilovoltage (kV) X-ray beams in order to perform the in vivo dosimetry during image guidance in radiotherapy. The performance characteristics of high sensitivity MOSFET dosimeters were investigated for 80, 90, 100, 110, 120, and 125 kV X-ray beams used for imaging in radiotherapy. This study was performed using Clinac 2100 C/D medical electron linear accelerator with on-board imaging and kV cone beam computed tomography system. The characteristics studied in this work include energy dependence, angular dependence, and linearity. The X-ray beam outputs were measured as per American Association of Physicists in Medicine (AAPM) TG 61 recommendations using PTW parallel plate (PP) ionization chamber, which was calibrated in terms of air kerma (Nk) by the National Standard Laboratory. The MOSFET dosimeters were calibrated against the PP ionization chamber for all the kV X-ray beams and the calibration coefficient was found to be 0.11 cGy/mV with a standard deviation of about ±1%. The response of MOSFET was found to be energy independent for the kV X-ray energies used in this study. The response of the MOSFET dosimeter was also found independent of angle of incidence for the gantry angles in the range of 0° to 360° in-air as well as at 3 cm depth in tissue equivalent phantom.

Tectonics and Current Plate Motions of Northern Vancouver Island and the Adjacent Mainland

NASA Astrophysics Data System (ADS)

Jiang, Y.; Leonard, L. J.; Henton, J.; Hyndman, R. D.

2016-12-01

Northern Vancouver Island comprises a complex transition zone along the western margin of the North America plate, between the subducting Juan de Fuca plate to the south and the transcurrent Queen Charlotte Fault to the north off Haida Gwaii. The tectonic history and seismic potential for this region are unclear. Here we present current plate motions for northern Vancouver Island and the adjacent mainland, determined from continuous and campaign GPS measurements processed in a consistent manner. Immediately to the north of the mid-Vancouver Island Nootka Fault Zone, the northern limit of Juan de Fuca plate subduction, GPS velocity vectors show slower Explorer plate subduction than the Juan de Fuca Plate. Off northernmost Vancouver Island, the Winona Block is possibly converging at a slow rate that decreases northward to zero. We find a constant northward margin-parallel translation of up to 5 mm/year from northern Vancouver Island extending to Alaska. The southern limit of this translation coincides with areas of high heat flow that may reflect extension and the northern limit of episodic tremor and slip (ETS) on the Cascadia megathrust. The origin of the northward translation is poorly understood. We find a mainland coastal shear zone extends as far south as northern Vancouver Island where the offshore plate boundary is likely subduction. The pattern of the observed coastal shear cannot reflect interseismic locking on a major offshore transcurrent fault. The geodetically determined mainland coastal zone velocities decrease landward from 5 to 0 mm/yr across a region where no active faults have been identified and there is very little current seismicity. In Haida Gwaii, oblique convergence is apparent in the GPS data, consistent with partitioning between margin-parallel and margin-perpendicular strain. After removing the margin parallel translation from the data, we determine an average maximum locking depth of 15 km for the Queen Charlotte transcurrent fault, consistent with seismicity and seismic structure data.

Gust Acoustics Computation with a Space-Time CE/SE Parallel 3D Solver

NASA Technical Reports Server (NTRS)

Wang, X. Y.; Himansu, A.; Chang, S. C.; Jorgenson, P. C. E.; Reddy, D. R. (Technical Monitor)

2002-01-01

The benchmark Problem 2 in Category 3 of the Third Computational Aero-Acoustics (CAA) Workshop is solved using the space-time conservation element and solution element (CE/SE) method. This problem concerns the unsteady response of an isolated finite-span swept flat-plate airfoil bounded by two parallel walls to an incident gust. The acoustic field generated by the interaction of the gust with the flat-plate airfoil is computed by solving the 3D (three-dimensional) Euler equations in the time domain using a parallel version of a 3D CE/SE solver. The effect of the gust orientation on the far-field directivity is studied. Numerical solutions are presented and compared with analytical solutions, showing a reasonable agreement.

Morphology of Proeutectoid Ferrite

NASA Astrophysics Data System (ADS)

Yin, Jiaqing; Hillert, Mats; Borgenstam, Annika

2017-03-01

The morphology of grain boundary nucleated ferrite particles in iron alloys with 0.3 mass pct carbon has been classified according to the presence of facets. Several kinds of particles extend into both grains of austenite and have facets to both. It is proposed that they all belong to a continuous series of shapes. Ferrite plates can nucleate directly on the grain boundary but can also develop from edges on many kinds of particles. Feathery structures of parallel plates on both sides of a grain boundary can thus form. In sections, parallel to their main growth direction, plates have been seen to extend the whole way from the nucleation site at the grain boundary and to the growth front. This happens in the whole temperature range studied from 973 K to 673 K (700 °C to 400 °C). The plates thus grow continuously and not by subunits stopping at limited length and continuing the growth by new ones nucleating. Sometimes, the plates have ridges and in oblique sections they could be mistaken for the start of new plates. No morphological signs were observed indicating a transition between Widmanstätten ferrite and bainitic ferrite. It is proposed that there is only one kind of acicular ferrite.

Vertical counterflow evaporative cooler

DOEpatents

Bourne, Richard C.; Lee, Brian Eric; Callaway, Duncan

2005-01-25

An evaporative heat exchanger having parallel plates that define alternating dry and wet passages. A water reservoir is located below the plates and is connected to a water distribution system. Water from the water distribution system flows through the wet passages and wets the surfaces of the plates that form the wet passages. Air flows through the dry passages, mixes with air below the plates, and flows into the wet passages before exiting through the top of the wet passages.

Analysis of bacterial fatty acids by flow modulated comprehensive two-dimensional gas chromatography with parallel flame ionization detector/mass spectrometry.

PubMed

Gu, Qun; David, Frank; Lynen, Frédéric; Rumpel, Klaus; Xu, Guowang; De Vos, Paul; Sandra, Pat

2010-06-25

Comprehensive two-dimensional gas chromatography (GCxGC) offers an interesting tool for profiling bacterial fatty acids. Flow modulated GCxGC using a commercially available system was evaluated, different parameters such as column flows and modulation time were optimized. The method was tested on bacterial fatty acid methyl esters (BAMEs) from Stenotrophomonas maltophilia LMG 958T by using parallel flame ionization detector (FID)/mass spectrometry (MS). The results are compared to data obtained using a thermal modulated GCxGC system. The data show that flow modulated GCxGC-FID/MS method can be applied in a routine environment and offers interesting perspectives for chemotaxonomy of bacteria.

Flexure Based Linear and Rotary Bearings

NASA Technical Reports Server (NTRS)

Voellmer, George M. (Inventor)

2016-01-01

A flexure based linear bearing includes top and bottom parallel rigid plates; first and second flexures connecting the top and bottom plates and constraining exactly four degrees of freedom of relative motion of the plates, the four degrees of freedom being X and Y axis translation and rotation about the X and Y axes; and a strut connecting the top and bottom plates and further constraining exactly one degree of freedom of the plates, the one degree of freedom being one of Z axis translation and rotation about the Z axis.

Quadruple parallel mass Spectrometry for analysis of vitamin D and triacylglycerols in a dietary supplement

USDA-ARS?s Scientific Manuscript database

A ‘dilute-and-shoot’ method for vitamin D and triacylglycerols is demonstrated that employed four mass spectrometers, operating in different ionization modes, for a ‘quadruple parallel mass spectrometry’ analysis, plus three other detectors, for seven detectors overall. Sets of five samples of diet...

Artificial dielectric stepped-refractive-index lens for the terahertz region.

PubMed

Hernandez-Serrano, A I; Mendis, Rajind; Reichel, Kimberly S; Zhang, Wei; Castro-Camus, E; Mittleman, Daniel M

2018-02-05

In this paper we theoretically and experimentally demonstrate a stepped-refractive-index convergent lens made of a parallel stack of metallic plates for terahertz frequencies based on artificial dielectrics. The lens consist of a non-uniformly spaced stack of metallic plates, forming a mirror-symmetric array of parallel-plate waveguides (PPWGs). The operation of the device is based on the TE 1 mode of the PPWG. The effective refractive index of the TE 1 mode is a function of the frequency of operation and the spacing between the plates of the PPWG. By varying the spacing between the plates, we can modify the local refractive index of the structure in every individual PPWG that constitutes the lens producing a stepped refractive index profile across the multi stack structure. The theoretical and experimental results show that this structure is capable of focusing a 1 cm diameter beam to a line focus of less than 4 mm for the design frequency of 0.18 THz. This structure shows that this artificial-dielectric concept is an important technology for the fabrication of next generation terahertz devices.

Means for obtaining a metal ion beam from a heavy-ion cyclotron source

DOEpatents

Hudson, E.D.; Mallory, M.L.

1975-08-01

A description is given of a modification to a cyclotron ion source used in producing a high intensity metal ion beam. A small amount of an inert support gas maintains the usual plasma arc, except that it is necessary for the support gas to have a heavy mass, e.g., xenon or krypton as opposed to neon. A plate, fabricated from the metal (or anything that can be sputtered) to be ionized, is mounted on the back wall of the ion source arc chamber and is bombarded by returning energetic low-charged gas ions that fail to cross the initial accelerating gap between the ion source and the accelerating electrode. Some of the atoms that are dislodged from the plate by the returning gas ions become ionized and are extracted as a useful beam of heavy ions. (auth)

Spontaneous-Desorption Ionizer for a TOF-MS

NASA Technical Reports Server (NTRS)

Schultz, J. Albert

2006-01-01

A time-of-flight mass spectrometer (TOF-MS) like the one mentioned in the immediately preceding article has been retrofitted with an ionizer based on a surface spontaneous-desorption process. This ionizer includes an electron multiplier in the form of a microchannel plate (MCP). Relative to an ionizer based on a hot-filament electron source, this ionizer offers advantages of less power consumption and greater mechanical ruggedness. The current density and stability characteristics of the electron emission of this ionizer are similar to those of a filament-based ionizer. In tests of various versions of this ionizer in the TOF-MS, electron currents up to 100 nA were registered. Currents of microamperes or more - great enough to satisfy requirements in most TOFMS applications - could be obtained by use of MCPs different from those used in the tests, albeit at the cost of greater bulk. One drawback of this ionizer is that the gain of the MCP decreases as a function of the charge extracted thus far; the total charge that can be extracted over the operational lifetime is about 1 coulomb. An MCP in the ion-detector portion of the TOF-MS is subject to the same limitation.

Beam perturbation characteristics of a 2D transmission silicon diode array, Magic Plate

PubMed Central

Alrowaili, Ziyad A.; Lerch, Michael L.F.; Petasecca, Marco; Carolan, Martin G.; Metcalfe, Peter E.

2016-01-01

The main objective of this study is to demonstrate the performance characteristics of the Magic Plate (MP) system when operated upstream of the patient in transmission mode (MPTM). The MPTM is an essential component of a real‐time QA system designed for operation during radiotherapy treatment. Of particular interest is a quantitative study into the influence of the MP on the radiation beam quality at several field sizes and linear accelerator potential differences. The impact is measured through beam perturbation effects such as changes in the skin dose and/or percentage depth dose (PDD) (both in and out of field). The MP was placed in the block tray of a Varian linac head operated at 6, 10 and 18 MV beam energy. To optimize the MPTM operational setup, two conditions were investigated and each setup was compared to the case where no MP is positioned in place (i.e., open field): (i) MPTM alone and (ii) MPTM with a thin passive contamination electron filter. The in‐field and out‐of‐field surface doses of a solid water phantom were investigated for both setups using a Markus plane parallel (Model N23343) and Attix parallel‐plate, MRI model 449 ionization chambers. In addition, the effect on the 2D dose distribution measured by the Delta4 QA system was also investigated. The transmission factor for both of these MPTM setups in the central axis was also investigated using a Farmer ionization chamber (Model 2571A) and an Attix ionization chamber. Measurements were performed for different irradiation field sizes of 5×5 cm2 and 10×10 cm2. The change in the surface dose relative to dmax was measured to be less than 0.5% for the 6 MV, 10 MV, and 18 MV energy beams. Transmission factors measured for both set ups (i & ii above) with 6 MV, 10 MV, and 18 MV at a depth of dmax and a depth of 10 cm were all within 1.6% of open field. The impact of both the bare MPTM and the MPTM with 1 mm buildup on 3D dose distribution in comparison to the open field investigated using the Delta4 system and both the MPTM versions passed standard clinical gamma analysis criteria. Two MPTM operational setups were studied and presented in this article. The results indicate that both versions may be suitable for the new real‐time megavoltage photon treatment delivery QA system under development. However, the bare MPTM appears to be slightly better suited of the two MP versions, as it minimally perturbs the radiation field and does not lead to any significant increase in skin dose to the patient. PACS number(s): 87.50.up, 87.53.Bn, 87.55.N, 87.55.Qr, 87.56.Fc. PMID:27074475

Static analysis of the hull plate using the finite element method

NASA Astrophysics Data System (ADS)

Ion, A.

2015-11-01

This paper aims at presenting the static analysis for two levels of a container ship's construction as follows: the first level is at the girder / hull plate and the second level is conducted at the entire strength hull of the vessel. This article will describe the work for the static analysis of a hull plate. We shall use the software package ANSYS Mechanical 14.5. The program is run on a computer with four Intel Xeon X5260 CPU processors at 3.33 GHz, 32 GB memory installed. In terms of software, the shared memory parallel version of ANSYS refers to running ANSYS across multiple cores on a SMP system. The distributed memory parallel version of ANSYS (Distributed ANSYS) refers to running ANSYS across multiple processors on SMP systems or DMP systems.

Casimir force in a Lorentz violating theory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Frank, Mariana; Turan, Ismail

2006-08-01

We study the effects of the minimal extension of the standard model including Lorentz violation on the Casimir force between two parallel conducting plates in the vacuum. We provide explicit solutions for the electromagnetic field using scalar field analogy, for both the cases in which the Lorentz violating terms come from the CPT-even or CPT-odd terms. We also calculate the effects of the Lorentz violating terms for a fermion field between two parallel conducting plates and analyze the modifications of the Casimir force due to the modifications of the Dirac equation. In all cases under consideration, the standard formulas formore » the Casimir force are modified by either multiplicative or additive correction factors, the latter case exhibiting different dependence on the distance between the plates.« less

A new ring-shaped graphite monitor ionization chamber

NASA Astrophysics Data System (ADS)

Yoshizumi, M. T.; Caldas, L. V. E.

2010-07-01

A ring-shaped monitor ionization chamber was developed at the Instituto de Pesquisas Energéticas e Nucleares. This ionization chamber presents an entrance window of aluminized polyester foil. The guard ring and collecting electrode are made of graphite coated Lucite plates. The main difference between this new ionization chamber and commercial monitor chambers is its ring-shaped design. The new monitor chamber has a central hole, allowing the passage of the direct radiation beam without attenuation; only the penumbra radiation is measured by the sensitive volume. This kind of ionization chamber design has already been tested, but using aluminium electrodes. By changing the electrode material from aluminium to a graphite coating, an improvement in the chamber response stability was expected. The pre-operational tests, as saturation curve, recombination loss and polarity effect showed satisfactory results. The repeatability and the long-term stability tests were also evaluated, showing good agreement with international recommendations.

Paradigm shifts in plasma processing and application of fundamental kinetics to problems targeting 5 nm technology device technology

NASA Astrophysics Data System (ADS)

Chen, Lee

2016-09-01

It is often said that semiconductor technology is approaching the end of scaling. While fundamental device limits do approach, plasma etching has been doing the heavy lifting to supplement the basic limits in lithography. RF plasmas, pulsing in many forms, diffusion plasmas are but a few of the important developments over the last 20 years that have succeeded in the seemingly impossible tasks. The commonality of these plasmas is being self-consistent: their near-Boltzmann EEDf maintains ionization with its tail while providing charge-balance with its Te . To control the plasma chemistry is to control its EEDf; the entanglement of ionization with charge-balance in self-consistent plasmas places a constraint on the decoupling of plasma chemistry from ionization. Example like DC/RF parallel-plate hybridizes stochastic heating with DC-cathode injected e- -beam. While such arrangement offers some level of decoupling, it raised more questions than what it helped answered along the lines of beam-plasma instabilities, bounce-resonance ionization, etc. Pure e- -beam plasmas could be a drastic departure from the self-consistent plasmas. Examples like the NRL e- -beam system and the more recent TEL NEP (Nonambipolar e- Plasma) show strong decoupling of Te from ionization but it is almost certain, many more questions lurk: the functions connecting collisional relaxation with instabilities, the channels causing the dissociation of large fluorocarbons (controlling the ion-to- radical ratio), the production of the damaging deep UV in e- -beam plasmas, etc., and the list goes on. IADf is one factor on feature-profile and IEDf determines the surgical surface-excitation governing the selectivity, and both functions have Ti as the origin; what controls the e- -beam plasmas' Ti ? RF-bias has served well in applications requiring energetic excitation but, are there ways to improve the IEDf tightness? What are the adverse side-effects of ``improved IEDf''? Decades ago an infant RF-plasma was thrown into the dry-etch arena and it hit the ground running with much of the understandings as after the facts. While the etching industry enjoys the heavy lifting by the successful self-consistent plasmas, perhaps time can be used on front-loaded soul searching of the ``maybe needed'' plasmas, for the future etching needs.

The Poisson-Boltzmann theory for the two-plates problem: some exact results.

PubMed

Xing, Xiang-Jun

2011-12-01

The general solution to the nonlinear Poisson-Boltzmann equation for two parallel charged plates, either inside a symmetric electrolyte, or inside a 2q:-q asymmetric electrolyte, is found in terms of Weierstrass elliptic functions. From this we derive some exact asymptotic results for the interaction between charged plates, as well as the exact form of the renormalized surface charge density.

Resin Characterization

DTIC Science & Technology

2015-06-01

environmental test chamber attachment to control temperature and disposable parallel plates . The experiment can be stopped when the sample...is auto-stopping when its torque limit is reached and to prevent too high of an extent of cure that could make removal of the disposable plates from...separated by a 0.025-mm-thick Teflon spacer (International Crystal Labs) or pressed with potassium bromide (KBr) powder into pellets. The salt plate

On-top density functionals for the short-range dynamic correlation between electrons of opposite and parallel spin

NASA Astrophysics Data System (ADS)

Hollett, Joshua W.; Pegoretti, Nicholas

2018-04-01

Separate, one-parameter, on-top density functionals are derived for the short-range dynamic correlation between opposite and parallel-spin electrons, in which the electron-electron cusp is represented by an exponential function. The combination of both functionals is referred to as the Opposite-spin exponential-cusp and Fermi-hole correction (OF) functional. The two parameters of the OF functional are set by fitting the ionization energies and electron affinities, of the atoms He to Ar, predicted by ROHF in combination with the OF functional to the experimental values. For ionization energies, the overall performance of ROHF-OF is better than completely renormalized coupled-cluster [CR-CC(2,3)] and better than, or as good as, conventional density functional methods. For electron affinities, the overall performance of ROHF-OF is less impressive. However, for both ionization energies and electron affinities of third row atoms, the mean absolute error of ROHF-OF is only 3 kJ mol-1.

Method and apparatus for generating radiation utilizing DC to AC conversion with a conductive front

DOEpatents

Dawson, John M.; Mori, Warren B.; Lai, Chih-Hsiang; Katsouleas, Thomas C.

1998-01-01

Method and apparatus for generating radiation of high power, variable duration and broad tunability over several orders of magnitude from a laser-ionized gas-filled capacitor array. The method and apparatus convert a DC electric field pattern into a coherent electromagnetic wave train when a relativistic ionization front passes between the capacitor plates. The frequency and duration of the radiation is controlled by the gas pressure and capacitor spacing.

LiF TLD-100 as a dosimeter in high energy proton beam therapy--can it yield accurate results?

PubMed

Zullo, John R; Kudchadker, Rajat J; Zhu, X Ronald; Sahoo, Narayan; Gillin, Michael T

2010-01-01

In the region of high-dose gradients at the end of the proton range, the stopping power ratio of the protons undergoes significant changes, allowing for a broad spectrum of proton energies to be deposited within a relatively small volume. Because of the potential linear energy transfer dependence of LiF TLD-100 (thermolumescent dosimeter), dose measurements made in the distal fall-off region of a proton beam may be less accurate than those made in regions of low-dose gradients. The purpose of this study is to determine the accuracy and precision of dose measured using TLD-100 for a pristine Bragg peak, particularly in the distal fall-off region. All measurements were made along the central axis of an unmodulated 200-MeV proton beam from a Probeat passive beam-scattering proton accelerator (Hitachi, Ltd., Tokyo, Japan) at varying depths along the Bragg peak. Measurements were made using TLD-100 powder flat packs, placed in a virtual water slab phantom. The measurements were repeated using a parallel plate ionization chamber. The dose measurements using TLD-100 in a proton beam were accurate to within +/-5.0% of the expected dose, previously seen in our past photon and electron measurements. The ionization chamber and the TLD relative dose measurements agreed well with each other. Absolute dose measurements using TLD agreed with ionization chamber measurements to within +/- 3.0 cGy, for an exposure of 100 cGy. In our study, the differences in the dose measured by the ionization chamber and those measured by TLD-100 were minimal, indicating that the accuracy and precision of measurements made in the distal fall-off region of a pristine Bragg peak is within the expected range. Thus, the rapid change in stopping power ratios at the end of the range should not affect such measurements, and TLD-100 may be used with confidence as an in vivo dosimeter for proton beam therapy. Copyright 2010 American Association of Medical Dosimetrists. Published by Elsevier Inc. All rights reserved.

Measurements of output factors with different detector types and Monte Carlo calculations of stopping-power ratios for degraded electron beams.

PubMed

Björk, Peter; Knöös, Tommy; Nilsson, Per

2004-10-07

The aim of the present study was to investigate three different detector types (a parallel-plate ionization chamber, a p-type silicon diode and a diamond detector) with regard to output factor measurements in degraded electron beams, such as those encountered in small-electron-field radiotherapy and intraoperative radiation therapy (IORT). The Monte Carlo method was used to calculate mass collision stopping-power ratios between water and the different detector materials for these complex electron beams (nominal energies of 6, 12 and 20 MeV). The diamond detector was shown to exhibit excellent properties for output factor measurements in degraded beams and was therefore used as a reference. The diode detector was found to be well suited for practical measurements of output factors, although the water-to-silicon stopping-power ratio was shown to vary slightly with treatment set-up and irradiation depth (especially for lower electron energies). Application of ionization-chamber-based dosimetry, according to international dosimetry protocols, will introduce uncertainties smaller than 0.3% into the output factor determination for conventional IORT beams if the variation of the water-to-air stopping-power ratio is not taken into account. The IORT system at our department includes a 0.3 cm thin plastic scatterer inside the therapeutic beam, which furthermore increases the energy degradation of the electrons. By ignoring the change in the water-to-air stopping-power ratio due to this scatterer, the output factor could be underestimated by up to 1.3%. This was verified by the measurements. In small-electron-beam dosimetry, the water-to-air stopping-power ratio variation with field size could mostly be ignored. For fields with flat lateral dose profiles (>3 x 3 cm2), output factors determined with the ionization chamber were found to be in close agreement with the results of the diamond detector. For smaller field sizes the lateral extension of the ionization chamber hampers its use. We therefore recommend that the readily available silicon diode detector should be used for output factor measurements in complex electron fields.

Displacement of Enterococcus faecalis from hydrophobic and hydrophilic substrata by Lactobacillus and Streptococcus spp. as studied in a parallel plate flow chamber.

PubMed Central

Millsap, K; Reid, G; van der Mei, H C; Busscher, H J

1994-01-01

The displacement of Enterococcus faecalis 1131 from hydrophobic and hydrophilic substrata by isolates of Lactobacillus casei 36 and Streptococcus hyointestinalis KM1 was studied in a parallel plate flow chamber. The experiments were conducted with either 10 mM potassium phosphate buffer or human urine as the suspending fluid, and adhesion and displacement were measured by real-time in situ image analysis. The results showed that E. faecalis 1131 was displaced by lactobacilli (31%) and streptococci (74%) from fluorinated ethylene propylene in buffer and that displacement by lactobacilli was even more effective on a glass substratum in urine (54%). The passage of an air-liquid interface significantly impacted on adhesion, especially when the surface had been challenged with lactobacilli (up to 100% displacement) or streptococci (up to 94% displacement). These results showed that the parallel plate flow system with real-time in situ image analysis was effective for studying bacterial adhesion and that uropathogenic enterococci can be displaced by indigenous bacteria. Images PMID:8031082

Vibration energy harvesting using a piezoelectric circular diaphragm array.

PubMed

Wang, Wei; Yang, Tongqing; Chen, Xurui; Yao, Xi

2012-09-01

This paper presents a method for harvesting electric energy from mechanical vibration using a mechanically excited piezoelectric circular membrane array. The piezoelectric circular diaphragm array consists of four plates with series and parallel connection, and the electrical characteristics of the array are examined under dynamic conditions. With an optimal load resistor of 160 kΩ, an output power of 28 mW was generated from the array in series connection at 150 Hz under a prestress of 0.8 N and a vibration acceleration of 9.8 m/s(2), whereas a maximal output power of 27 mW can be obtained from the array in parallel connection through a resistive load of 11 kΩ under the same frequency, prestress, and acceleration conditions. The results show that using a piezoelectric circular diaphragm array can significantly increase the output of energy compared with the use of a single plate. By choosing an appropriate connection pattern (series or parallel connections) among the plates, the equivalent impedance of the energy harvesting devices can be tailored to meet the matched load of different applications for maximal power output.

Design and Fabrication of TES Detector Modules for the TIME-Pilot [CII] Intensity Mapping Experiment

NASA Astrophysics Data System (ADS)

Hunacek, J.; Bock, J.; Bradford, C. M.; Bumble, B.; Chang, T.-C.; Cheng, Y.-T.; Cooray, A.; Crites, A.; Hailey-Dunsheath, S.; Gong, Y.; Kenyon, M.; Koch, P.; Li, C.-T.; O'Brient, R.; Shirokoff, E.; Shiu, C.; Staniszewski, Z.; Uzgil, B.; Zemcov, M.

2016-08-01

We are developing a series of close-packed modular detector arrays for TIME-Pilot, a new mm-wavelength grating spectrometer array that will map the intensity fluctuations of the redshifted 157.7 \\upmu m emission line of singly ionized carbon ([CII]) from redshift z ˜ 5 to 9. TIME-Pilot's two banks of 16 parallel-plate waveguide spectrometers (one bank per polarization) will have a spectral range of 183-326 GHz and a resolving power of R ˜ 100. The spectrometers use a curved diffraction grating to disperse and focus the light on a series of output arcs, each sampled by 60 transition edge sensor (TES) bolometers with gold micro-mesh absorbers. These low-noise detectors will be operated from a 250 mK base temperature and are designed to have a background-limited NEP of {˜ }10^{-17} mathrm {W}/mathrm {Hz}^{1/2}. This proceeding presents an overview of the detector design in the context of the TIME-Pilot instrument. Additionally, a prototype detector module produced at the Microdevices Laboratory at JPL is shown.

A numerical study of neutral-plasma interaction in magnetically confined plasmas

NASA Astrophysics Data System (ADS)

Taheri, S.; Shumlak, U.; King, J. R.

2017-10-01

Interactions between plasma and neutral species can have a large effect on the dynamic behavior of magnetically confined plasma devices, such as the edge region of tokamaks and the plasma formation of Z-pinches. The presence of neutrals can affect the stability of the pinch and change the dynamics of the pinch collapse, and they can lead to deposition of high energy particles on the first wall. However, plasma-neutral interactions can also have beneficial effects such as quenching the disruptions in tokamaks. In this research a reacting plasma-neutral model, which combines a magnetohydrodynamic (MHD) plasma model with a gas dynamic neutral fluid model, is used to study the interaction between plasma and neutral gas. Incorporating this model into NIMROD allows the study of electron-impact ionization, radiative recombination, and resonant charge-exchange in plasma-neutral systems. An accelerated plasma moving through a neutral gas background is modeled in both a parallel plate and a coaxial electrode configuration to explore the effect of neutral gas in pinch-like devices. This work is supported by a Grant from US DOE.

APPARATUS FOR THE MASS ANALYSIS OF PLASMA ON A CONTINUOUS BASIS

DOEpatents

Neidigh, R.V.

1963-07-01

An apparatus for the mass analysis of plasmas on a continuous basis is described. The apparatus comprises a pair of parallel electrodes in a tubular member which serve as a velocity-selecting region for ions drawn by an accelerating potential through a tapered nose cone affixed to the tubular member. The magnetic force and electrostatic forces in the velocity-selecting region are made equal and opposite in direction to prevent the ionic species from striking either of the electrodes as they traverse the region. A pair of parallel plates is positioned within the tubular member and in alignment with the electrodes, but displaced slightly so as not to be seen by direct light coming through the entrance slit of the nose cone, and one of these plates serves as a collector plate. This collector plate is coupled to the vertical amplifier of an oscilloscope or other recorder to provide a continuous indication of the ionic coinposition of the plasma under analysis. ( DELTA EC)

Evolution and hydration of the Juan de Fuca crust and uppermost mantle: a plate-scale seismic investigation from ridge to trench

NASA Astrophysics Data System (ADS)

Carbotte, S. M.; Canales, J.; Carton, H. D.; Nedimovic, M. R.; Han, S.; Marjanovic, M.; Gibson, J. C.; Janiszewski, H. A.; Horning, G.; Delescluse, M.; Watremez, L.; Farkas, A.; Biescas Gorriz, B.; Bornstein, G.; Childress, L. B.; Parker, B.

2012-12-01

The evolution of oceanic lithosphere involves incorporation of water into the physical and chemical structure of the crust and shallow mantle through fluid circulation, which initiates at the mid-ocean ridge and continues on the ridge flanks long after crustal formation. At subduction zones, water stored and transported with the descending plate is gradually released at depth, strongly influencing subduction zone processes. Cascadia is a young-lithosphere end member of the global subduction system where relatively little hydration of the downgoing Juan de Fuca (JdF) plate is expected due to its young age and presumed warm thermal state. However, numerous observations support the abundant presence of water within the subduction zone, suggesting that the JdF plate is significantly hydrated prior to subduction. Knowledge of the state of hydration of the JdF plate is limited, with few constraints on crustal and upper mantle structure. During the Cascadia Ridge-to-Trench experiment conducted in June-July 2012 over 4000 km of active source seismic data were acquired as part of a study of the evolution and state of hydration of the crust and shallow mantle of the JdF plate prior to subduction at the Cascadia margin. Coincident long-streamer (8 km) multi-channel seismic (MCS) and wide-angle ocean bottom seismometer (OBS) data were acquired in a two-ship program with the R/V Langseth (MGL1211), and R/V Oceanus (OC1206A). Our survey included two ridge-perpendicular transects across the full width of the JdF plate, a long trench-parallel line ~10 km seaward of the Cascadia deformation front, as well as three fan lines to study mantle anisotropy. The plate transects were chosen to provide reference sections of JdF plate evolution over the maximum range of JdF plate ages (8-9 Ma), offshore two contrasting regions of the Cascadia Subduction zone, and provide the first continuous ridge-to-trench images acquired at any oceanic plate. The trench-parallel line was designed to characterize variations in plate structure and hydration linked to JdF plate segmentation for over 450 km along the margin. Shipboard brute stacks of the MCS data reveal evidence for reactivation of abyssal hill faulting in the plate interior far from the trench. Ridgeward-dipping lower crustal reflectors are observed, similar to those observed in mature Pacific crust elsewhere, as well as conjugate reflectivity near the deformation front along the Oregon transect. Bright intracrustal reflectivity is also observed along the trench-parallel transect with marked changes in reflectivity along the Oregon and Washington margins. Initial inspection of the OBS record sections indicate good quality data with the expected oceanic crustal and upper mantle P-wave arrivals: Ps and Pg refractions through sedimentary and igneous layers, respectively, PmP wide-angle reflections from the crust-mantle transition zone, and Pn upper mantle refractions. The Pg-PmP-Pn triplication is typically observed at 40-50 km source-receiver offsets. Pn characteristics show evidence for upper mantle azimuthal anisotropic propagation: along the plate transects Pn is typically weaker and difficult to observe beyond ~80 km offsets, while along the trench-parallel transect Pn arrivals have higher amplitude and are easily observed up to source-receiver offsets of 160-180 km. An overview on the Cascadia Ridge to Trench data acquisition program and preliminary results will be presented.

3D dynamics of crustal deformation driven by oblique subduction: Northern and Central Andes

NASA Astrophysics Data System (ADS)

Schütt, Jorina M.; Whipp, David M., Jr.

2017-04-01

The geometry and relative motion of colliding plates will affect how and where they deform. In oblique subduction systems, factors such as the dip angle of the subducting plate and the convergence obliquity, as well as the presence of weak zones in the overriding plate, all influence how oblique convergence is partitioned onto various fault systems in the overriding plate. The partitioning of strain into margin-normal slip on the plate-bounding fault and horizontal shearing on a strike-slip system parallel to the margin is mainly controlled by the margin-parallel shear forces acting on the plate interface and the strength of the continental crust. While these plate interface forces are influenced by the dip angle of the subducting plate (i.e., the length of plate interface in the frictional domain) and the obliquity angle between the normal to the plate margin and the plate convergence vector, the strength of the continental crust in the upper plate is strongly affected by the presence or absence of weak zones such as regions of arc volcanism, pre-existing fault systems, or boundaries of stronger crustal blocks. In order to investigate which of these factors are most important in controlling how the overriding continental plate deforms, we compare results of lithospheric-scale 3D numerical geodynamic experiments from two regions in the north-central Andes: the Northern Volcanic Zone (NVZ; 5°N - 3°S) and adjacent Peruvian Flat Slab Segment (PFSS; 3°S -14°S). The NVZ is characterized by a 35° subduction dip angle with an obliquity angle of about 40°, extensive volcanism and significant strain partitioning in the continental crust. In contrast, the PFSS is characterized by flat subduction (the slab flattens beneath the continent at around 100 km depth for several hundred kilometers), an obliquity angle of about 20°, no volcanism and minimal strain partitioning. The plate geometry and convergence obliquity for these regions are incorporated in 3D (1600 x 1600 x 160 km) numerical experiments of oceanic subduction beneath a continent, focusing on the conditions under which strain partitioning occurs in the continental plate. In addition to different slab geometries and obliquity angles, we consider the effect of a continental crustal of uniform strength (friction angle Φ=15^°) versus one including a weak zone in the continental crust (Φ=4^°) that runs parallel to the margin. Results of our experiments show that the obliquity angle has the largest effect on initiating strain partitioning, as expected based on strain partitioning theory, but strain partitioning is clearly enhanced by the presence of a continental weakness. Margin-parallel mass transport velocities in the continental sliver are similar to the values observed in the NVZ (about 1 cm/year) in models with a continental weakness and twice as high as those without. In addition, a shallower subduction angle results in formation of a wider continental sliver. Based upon our results, the lack of strain partitioning observed in the PFSS results from both a low convergence obliquity and lack of a weak zone in the continent, even though the shallow subduction should make strain partitioning more favorable.

MPI_XSTAR: MPI-based Parallelization of the XSTAR Photoionization Program

NASA Astrophysics Data System (ADS)

Danehkar, Ashkbiz; Nowak, Michael A.; Lee, Julia C.; Smith, Randall K.

2018-02-01

We describe a program for the parallel implementation of multiple runs of XSTAR, a photoionization code that is used to predict the physical properties of an ionized gas from its emission and/or absorption lines. The parallelization program, called MPI_XSTAR, has been developed and implemented in the C++ language by using the Message Passing Interface (MPI) protocol, a conventional standard of parallel computing. We have benchmarked parallel multiprocessing executions of XSTAR, using MPI_XSTAR, against a serial execution of XSTAR, in terms of the parallelization speedup and the computing resource efficiency. Our experience indicates that the parallel execution runs significantly faster than the serial execution, however, the efficiency in terms of the computing resource usage decreases with increasing the number of processors used in the parallel computing.

Application of parylene for surface (polymer) enhanced laser desorption/ionization of synthetic polymers.

PubMed

Miksa, Beata J; Sochacki, Marek; Sroka-Bartnicka, Anna; Uznański, Paweł; Nosal, Andrzej; Potrzebowski, Marek J

2013-04-15

Synthetic polymers of molecular masses up to a few kDa can be analyzed without the use of any matrix by direct laser desorption/ionization mass spectrometry (LDI-MS). In this technique, the surface of the sample plate plays a crucial role, and many attempts have been made to understand the influence of the surface on the ease of desorption. Since this technique requires no tedious sample pretreatment, it is a promising method for the rapid characterization of various synthetic polymers. Parylene (poly(p-xylylenes), PPX) was tested as a surface support for studying the molecular masses of biocompatible polymers: poly(ethylene glycol) (PEG), poly(L-lactide) (PLLA), and poly(methyl methacrylate) (PMMA). The average molecular masses of the polymers were: PEG (600.0 Da and 3.5 kDa), PMMA (2.0 kDa), and PLLA (2.8 kDa). LDI mass spectra of polymers deposited on parylene were enhanced by a factor of two over those obtained directly from the gold target plate. Modification of the surface of the target plate by the addition of a PPX layer extended the functionality of LDI-TOF MS, especially for the analysis of low-mass compounds. The LDI analysis using the PPX-coated target plate provided details of polymers including: end-group, composition, monomer unit, and molecular mass distribution. The average molecular weights of four tested polymers on the gold target plate and the PPX support were unchanged, indicating that sample degradation was not occurring despite the high energy of the laser beam. The LDI investigations showed that the PPX support boosted ion yields by a factor of two compared with the gold target plate. Copyright © 2013 John Wiley & Sons, Ltd.

Fundamentals of undervoltage breakdown through the Townsend mechanism

NASA Astrophysics Data System (ADS)

Cooley, James E.

The conditions under which an externally supplied pulse of electrons will induce breakdown in an undervoltaged, low-gain, DC discharge gap are experimentally and theoretically explored. The phenomenon is relevant to fundamental understanding of breakdown physics, to switching applications such as triggered spark gaps and discharge initiation in pulsed-plasma thrusters, and to gas-avalanche particle counters. A dimensionless theoretical description of the phenomenon is formulated and solved numerically. It is found that a significant fraction of the charge on the plates must be injected for breakdown to be achieved at low avalanche-ionization gain, when an electron undergoes fewer than approximately 10 ionizing collisions during one gap transit. It is also found that fewer injected electrons are required as the gain due to electron-impact ionization (alpha process) is increased, or as the sensitivity of the alpha process to electric field is enhanced by decreasing the reduced electric field (electric field divided by pressure, E/p). A predicted insensitivity to ion mobility implies that breakdown is determined during the first electron avalanche when space charge distortion is greatest. A dimensionless, theoretical study of the development of this avalanche reveals a critical value of the reduced electric field to be the value at the Paschen curve minimum divided by 1.6. Below this value, the net result of the electric field distortion is to increase ionization for subsequent avalanches, making undervoltage breakdown possible. Above this value, ionization for subsequent avalanches will be suppressed and undervoltage breakdown is not possible. Using an experimental apparatus in which ultraviolet laser pulses are directed onto a photo-emissive cathode of a parallel-plate discharge gap, it is found that undervoltage breakdown can occur through a Townsend-like mechanism through the buildup of successively larger avalanche generations. The minimum number of injected electrons required to achieve breakdown is measured in argon at pd values of 3-10 Torr-m. The required electron pulse magnitude was found to scale inversely with pressure and voltage in this parameter range. When higher-power infrared laser pulses were used to heat the cathode surface, a faster, streamer-like breakdown mechanism was occasionally observed. As an example application, an investigation into the requirements for initiating discharges in Gas-fed Pulsed Plasma Thrusters (GFPPTs) is conducted. Theoretical investigations based on order-of-magnitude characterizations of previous GFPPT designs reveal that high-conductivity arc discharges are required for critically-damped matching of circuit components, and that relatively fast streamer breakdown is preferable to minimize delay between triggering and current sheet formation. The faster breakdown mechanism observed in the experiments demonstrates that such a discharge process can occur. However, in the parameter space occupied by most thrusters, achieving the phenomenon by way of a space charge distortion caused purely by an electron pulse should not be possible. Either a transient change in the distribution of gas density, through ablation or desorption, or a thruster design that occupies a different parameter space, such as one that uses higher mass bits, higher voltages, or smaller electrode spacing, is required for undervoltage breakdown to occur.

A one-dimensional heat transfer model for parallel-plate thermoacoustic heat exchangers.

PubMed

de Jong, J A; Wijnant, Y H; de Boer, A

2014-03-01

A one-dimensional (1D) laminar oscillating flow heat transfer model is derived and applied to parallel-plate thermoacoustic heat exchangers. The model can be used to estimate the heat transfer from the solid wall to the acoustic medium, which is required for the heat input/output of thermoacoustic systems. The model is implementable in existing (quasi-)1D thermoacoustic codes, such as DeltaEC. Examples of generated results show good agreement with literature results. The model allows for arbitrary wave phasing; however, it is shown that the wave phasing does not significantly influence the heat transfer.

Design and analysis of all-dielectric broadband nonpolarizing parallel-plate beam splitters.

PubMed

Wang, Wenliang; Xiong, Shengming; Zhang, Yundong

2007-06-01

Past research on the all-dielectric nonpolarizing beam splitter is reviewed. With the aid of the needle thin-film synthesis method and the conjugate graduate refine method, three different split ratio nonpolarizing parallel-plate beam splitters over a 200 nm spectral range centered at 550 nm with incidence angles of 45 degrees are designed. The chosen materials component and the initial stack are based on the Costich and Thelen theories. The results of design and analysis show that the designs maintain a very low polarization ratio in the working range of the spectrum and has a reasonable angular field.

All-dielectric broadband non-polarizing parallel plate beam splitter operating between 450-650nm

NASA Astrophysics Data System (ADS)

Wang, Wenliang; Xiong, Shenming; Zhang, Yundong

2007-12-01

Past research on all-dielectric non-polarizing beam splitter is reviewed. With the aid of needle thin film synthesis method and conjugate graduate refining method, three non-polarizing parallel plate beam splitters with different split ratios over a 200nm spectral range centered at 550nm with incidence angle 45° are designed. Selection of material components and initial stack are based on Costich and Thelen's theory. The results of design and analysis show that it maintains a very low polarization ratio in the working range of spectrum and has a reasonable angular field.

Numerical Solution of the Navier-Stokes Equations for Steady Magnetohydrodynamic Flow Between Two Parallel Porous Plates with an Angular Velocity

NASA Astrophysics Data System (ADS)

Delhi Babu, R.; Ganesh, S.

2018-04-01

The Steady Laminar stream of an electrically directing thick, incompressible liquid between two parallel permeable plates of a divert within the sight of a transverse attractive field with an angular velocity when the liquid is being pulled back through both the dividers of the channel at a similar rate with a precise speed is examined. Numerical arrangement is acquired for various estimations of R (Suction Reynolds number) utilizing R-K Gill's technique and the diagrams of dimensionless functions f ' and f have been drawn.

Experimental Observation of the Effects of Translational and Rotational Electrode Misalignment on a Planar Linear Ion Trap Mass Spectrometer

NASA Astrophysics Data System (ADS)

Tian, Yuan; Decker, Trevor K.; McClellan, Joshua S.; Wu, Qinghao; De la Cruz, Abraham; Hawkins, Aaron R.; Austin, Daniel E.

2018-04-01

The performance of miniaturized ion trap mass analyzers is limited, in part, by the accuracy with which electrodes can be fabricated and positioned relative to each other. Alignment of plates in a two-plate planar LIT is ideal to characterize misalignment effects, as it represents the simplest possible case, having only six degrees of freedom (DOF) (three translational and three rotational). High-precision motorized actuators were used to vary the alignment between the two ion trap plates in five DOFs—x, y, z, pitch, and yaw. A comparison between the experiment and previous simulations shows reasonable agreement. Pitch, or the degree to which the plates are parallel along the axial direction, has the largest and sharpest impact to resolving power, with resolving power dropping noticeably with pitch misalignment of a fraction of a degree. Lateral displacement (x) and yaw (rotation of one plate, but plates remain parallel) both have a strong impact on ion ejection efficiency, but little effect on resolving power. The effects of plate spacing (y-displacement) on both resolving power and ion ejection efficiency are attributable to higher-order terms in the trapping field. Varying the DC (axial) trapping potential can elucidate the effects where more misalignments in more than one DOF affect performance. Implications of these results for miniaturized ion traps are discussed. [Figure not available: see fulltext.

Thin-Layer Chromatography/Desorption Electrospray Ionization Mass Spectrometry: Investigation of Goldenseal Alkaloids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Van Berkel, Gary J; Tomkins, Bruce A; Kertesz, Vilmos

2007-01-01

Desorption electrospray ionization mass spectrometry was investigated as a means to qualitatively identify and to quantify analytes directly from developed normal-phase thin layer chromatography plates. The atmospheric sampling capillary of a commercial ion trap mass spectrometer was extended to permit sampling and ionization of analytes in bands separated on intact TLC plates (up to 10 cm x 10 cm). A surface positioning software package and the appropriate hardware enabled computer-controlled surface scanning along the length of development lanes or at fixed RF value across the plates versus the stationary desorption electrospray emitter. Goldenseal (Hydrastis canadensis) and related alkaloids and commercialmore » dietary supplements were used as standards and samples. Alkaloid standards and samples were spotted and separated on aluminum- or glass-backed plates using established literature methods. The mass spectral signal levels as a function of desorption spray solvent were investigated with acetonitrile proving superior to methanol. The detection levels (ca. 5 ng each or 14 -28 pmol) in mass spectral full scan mode were determined statistically from the calibration curves (2.5 - 100 pmol) for the standards berberine, palmatine and hydrastinine spotted as a mixture and separated on the plates. Qualitative screening of the major alkaloids present in six different over-the-counter "goldenseal" dietary supplements was accomplished by obtaining full scan mass spectra during surface scans along the development lane in the direction of increasing RF value. In one sample, alkaloids were detected that strongly suggested the presence of at least one additional herb undeclared on the product label. These same data indicated the misidentification of one of the alkaloids in the TLC literature. Quantities of the alkaloids present in two of the samples determined using the mass spectral data were in reasonable agreement with the label values indicating the quantitative ability of the method. The advantage of mass spectral measurements in identifying and quantifying materials within overlapping bands and in providing positive identification for even minor species in a mixture was also demonstrated.« less

Multiscale modeling and simulation for polymer melt flows between parallel plates

NASA Astrophysics Data System (ADS)

Yasuda, Shugo; Yamamoto, Ryoichi

2010-03-01

The flow behaviors of polymer melt composed of short chains with ten beads between parallel plates are simulated by using a hybrid method of molecular dynamics and computational fluid dynamics. Three problems are solved: creep motion under a constant shear stress and its recovery motion after removing the stress, pressure-driven flows, and the flows in rapidly oscillating plates. In the creep/recovery problem, the delayed elastic deformation in the creep motion and evident elastic behavior in the recovery motion are demonstrated. The velocity profiles of the melt in pressure-driven flows are quite different from those of Newtonian fluid due to shear thinning. Velocity gradients of the melt become steeper near the plates and flatter at the middle between the plates as the pressure gradient increases and the temperature decreases. In the rapidly oscillating plates, the viscous boundary layer of the melt is much thinner than that of Newtonian fluid due to the shear thinning of the melt. Three different rheological regimes, i.e., the viscous fluid, viscoelastic liquid, and viscoelastic solid regimes, form over the oscillating plate according to the local Deborah numbers. The melt behaves as a viscous fluid in a region for ωτR≲1 , and the crossover between the liquidlike and solidlike regime takes place around ωτα≃1 (where ω is the angular frequency of the plate and τR and τα are Rouse and α relaxation time, respectively).

Multiscale modeling and simulation for polymer melt flows between parallel plates.

PubMed

Yasuda, Shugo; Yamamoto, Ryoichi

2010-03-01

The flow behaviors of polymer melt composed of short chains with ten beads between parallel plates are simulated by using a hybrid method of molecular dynamics and computational fluid dynamics. Three problems are solved: creep motion under a constant shear stress and its recovery motion after removing the stress, pressure-driven flows, and the flows in rapidly oscillating plates. In the creep/recovery problem, the delayed elastic deformation in the creep motion and evident elastic behavior in the recovery motion are demonstrated. The velocity profiles of the melt in pressure-driven flows are quite different from those of Newtonian fluid due to shear thinning. Velocity gradients of the melt become steeper near the plates and flatter at the middle between the plates as the pressure gradient increases and the temperature decreases. In the rapidly oscillating plates, the viscous boundary layer of the melt is much thinner than that of Newtonian fluid due to the shear thinning of the melt. Three different rheological regimes, i.e., the viscous fluid, viscoelastic liquid, and viscoelastic solid regimes, form over the oscillating plate according to the local Deborah numbers. The melt behaves as a viscous fluid in a region for omegatauR < approximately 1 , and the crossover between the liquidlike and solidlike regime takes place around omegataualpha approximately equal 1 (where omega is the angular frequency of the plate and tauR and taualpha are Rouse and alpha relaxation time, respectively).

Lighting system with heat distribution face plate

DOEpatents

Arik, Mehmet; Weaver, Stanton Earl; Stecher, Thomas Elliot; Kuenzler, Glenn Howard; Wolfe, Jr., Charles Franklin; Li, Ri

2013-09-10

Lighting systems having a light source and a thermal management system are provided. The thermal management system includes synthetic jet devices, a heat sink and a heat distribution face plate. The synthetic jet devices are arranged in parallel to one and other and are configured to actively cool the lighting system. The heat distribution face plate is configured to radially transfer heat from the light source into the ambient air.

Means for the focusing and acceleration of parallel beams of charged particles. [Patent application

DOEpatents

Maschke, A.W.

1980-09-23

Apparatus for focusing beams of charged particles comprising planar arrays of electrostatic quadrupoles. The array may be assembled from a single component which comprises a support plate containing uniform rows of poles. Each pole is separated by a hole through the plate designed to pass a beam. Two such plates may be positioned with their poles intermeshed to form a plurality of quadrupoles.

SU-F-T-552: A One-Year Evaluation of the QABeamChecker+ for Use with the CyberKnife System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gersh, J; Spectrum Medical Physics, LLC, Greenville, SC

Purpose: By attaching an adapter plate with fiducial markers to the QA BeamChecker+ (Standard Imaging, Inc., Middleton, WI), the output of the CyberKnife can be accurately, efficiently, and consistently evaluated. The adapter plate, known as the Cutting Board, allows for automated alignment of the QABC+ using the CK’s stereoscopic kV image-based treatment localization system (TLS). Described herein is an evaluation of the system following a year of clinical utilization. Methods: Based on a CT scan of the QABC+ and CB, a treatment plan is generated which delivers a beam to each of the 5 plane-parallel ionization chambers. Following absolute calibrationmore » of the CK, the QA plan is delivered, and baseline measurements are acquired (and automatically corrected for temperature and pressure). This test was performed at the beginning of each treatment day for a year. A calibration evaluation (using a water-equivalent slab and short thimble chamber) is performed every four weeks, or whenever the QABC+ detects a deviation of more than 1.0%. Results: During baseline evaluation, repeat measurements (n=10) were performed, with an average output of 0.25% with an SD of 0.11%. As a test of the reposition of the QABC+ and CB, ten additional measurements were performed where between each acquisition, the entire system was removed and re-positioned using the TLS. The average output deviation was 0.30% with a SD of 0.13%. During the course of the year, 187 QABC+ measurements and 13 slab-based measurements were performed. The output measurements of the QABC+ correlated well with slab-based measurements (R2=0.909). Conclusion: By using the QABC+ and CB, daily output was evaluated accurately, efficiently, and consistently. From setup to break-down (including analysis), this test required 5 minutes instead of approximately 15 using traditional techniques (collimator-mounted ionization chambers). Additionally, by automatically saving resultant output deviation to a database, trend analysis was simplified. Spectrum Medical Physics, LLC of Greenville, SC has a consulting contract with Standard Imaging of Middleton, WI.« less

The influence of air humidity on an unsealed ionization chamber in a linear accelerator.

PubMed

Blad, B; Nilsson, P; Knöös, T

1996-11-01

The safe and accurate delivery of the prescribed absorbed dose is the central function of the dose monitoring and beam stabilization system in a medical linear accelerator. The absorbed dose delivered to the patient during radiotherapy is often monitored by a transmission ionization chamber. Therefore it is of utmost importance that the chamber behaves correctly. We have noticed that the sensitivity of an unsealed chamber in a Philips SL linear accelerator changes significantly, especially during and after the summer season. The reason for this is probably a corrosion effect of the conductive plates in the chamber due to the increased relative humidity during hot periods. We have found that the responses of the different ion chamber plates change with variations in air humidity and that they do not return to their original values when the air humidity is returned to ambient conditions.

Identification of anaerobic bacteria by Bruker Biotyper matrix-assisted laser desorption ionization-time of flight mass spectrometry with on-plate formic acid preparation.

PubMed

Schmitt, Bryan H; Cunningham, Scott A; Dailey, Aaron L; Gustafson, Daniel R; Patel, Robin

2013-03-01

Identification of anaerobic bacteria using phenotypic methods is often time-consuming; methods such as 16S rRNA gene sequencing are costly and may not be readily available. We evaluated 253 clinical isolates of anaerobic bacteria using the Bruker MALDI Biotyper (Bruker Daltonics, Billerica, MA) matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) system with a user-supplemented database and an on-plate formic acid-based preparation method and compared results to those of conventional identification using biochemical testing or 16S rRNA gene sequencing. A total of 179 (70.8%) and 232 (91.7%) isolates were correctly identified to the species and genus levels, respectively, using manufacturer-recommended score cutoffs. MALDI-TOF MS offers a rapid, inexpensive method for identification of anaerobic bacteria.

Automated scanning of plastic nuclear track detectors using the Minnesota star scanner

NASA Technical Reports Server (NTRS)

Fink, P. J.; Waddington, C. J.

1986-01-01

The problems found in an attempt to adapt an automated scanner of astronomical plates, the Minnesota Automated Dual Plate Scanner (APS), to locating and measuring the etch pits produced by ionizing particles in plastic nuclear track detectors (CR-39) are described. A visual study of these pits was made to determine the errors introduced in determining positions and shapes. Measurements made under a low power microscope were compared with those from the APS.

Method and apparatus for generating radiation utilizing DC to AC conversion with a conductive front

DOEpatents

Dawson, J.M.; Mori, W.B.; Lai, C.H.; Katsouleas, T.C.

1998-07-14

Method and apparatus ar disclosed for generating radiation of high power, variable duration and broad tunability over several orders of magnitude from a laser-ionized gas-filled capacitor array. The method and apparatus convert a DC electric field pattern into a coherent electromagnetic wave train when a relativistic ionization front passes between the capacitor plates. The frequency and duration of the radiation is controlled by the gas pressure and capacitor spacing. 4 figs.

Heat transfer optimization for air-mist cooling between a stack of parallel plates

NASA Astrophysics Data System (ADS)

Issa, Roy J.

2010-06-01

A theoretical model is developed to predict the upper limit heat transfer between a stack of parallel plates subject to multiphase cooling by air-mist flow. The model predicts the optimal separation distance between the plates based on the development of the boundary layers for small and large separation distances, and for dilute mist conditions. Simulation results show the optimal separation distance to be strongly dependent on the liquid-to-air mass flow rate loading ratio, and reach a limit for a critical loading. For these dilute spray conditions, complete evaporation of the droplets takes place. Simulation results also show the optimal separation distance decreases with the increase in the mist flow rate. The proposed theoretical model shall lead to a better understanding of the design of fins spacing in heat exchangers where multiphase spray cooling is used.

Constrained ceramic-filled polymer armor

DOEpatents

Sandstrom, Donald J.; Calkins, Noel C.; Gac, Frank D.

1990-01-01

An armor system in which a plurality of constraint cells are mounted on a surface of a substrate, which is metal armor plate or a similar tough material, such that the cells almost completely cover the surface of the substrate. Each constraint cell has a projectile-receiving wall parallel to the substrate surface and has sides which are perpendicular to and surround the perimeter of the receiving wall. The cells are mounted such that, in one embodiment, the substrate surface serves as a sixth side or closure for each cell. Each cell has inside of it a plate, termed the front plate, which is parallel to and in contact with substantially all of the inside surface of the receiving wall. The balance of each cell is completely filled with a projectile-abrading material, which is a ceramic material in particulate form dispersed in a polymeric matrix.

Analysis of liquid-metal-jet impingement cooling in a corner region and for a row of jets

NASA Technical Reports Server (NTRS)

Siegel, R.

1975-01-01

A conformal mapping method was used to analyze liquid-metal-jet impingement heat transfer. The jet flow region and energy equation are transformed to correspond to uniform flow in a parallel plate channel with nonuniform heat addition along a portion of one wall. The exact solution for the wall-temperature distribution was obtained in the transformed channel, and the results are mapped back into the physical plane. Two geometries are analyzed. One is for a single slot jet directed either into an interior corner formed by two flat plates, or over the external sides of the corner; the flat plates are uniformly heated, and the corner can have various included angles. The heat-transfer coefficient at the stagnation point at the apex of the plates is obtained as a function of the corner angle, and temperature distributions are calculated along the heated walls. The second geometry is an infinite row of uniformly spaced parallel slot jets impinging normally against a uniformly heated plate. The heat-transfer behavior is obtained as a function of the spacing between the jets. Results are given for several jet Peclet numbers from 5 to 50.

High-throughput measurements of biochemical responses using the plate::vision multimode 96 minilens array reader.

PubMed

Huang, Kuo-Sen; Mark, David; Gandenberger, Frank Ulrich

2006-01-01

The plate::vision is a high-throughput multimode reader capable of reading absorbance, fluorescence, fluorescence polarization, time-resolved fluorescence, and luminescence. Its performance has been shown to be quite comparable with other readers. When the reader is integrated into the plate::explorer, an ultrahigh-throughput screening system with event-driven software and parallel plate-handling devices, it becomes possible to run complicated assays with kinetic readouts in high-density microtiter plate formats for high-throughput screening. For the past 5 years, we have used the plate::vision and the plate::explorer to run screens and have generated more than 30 million data points. Their throughput, performance, and robustness have speeded up our drug discovery process greatly.

The dynamics of plate tectonics and mantle flow: from local to global scales.

PubMed

Stadler, Georg; Gurnis, Michael; Burstedde, Carsten; Wilcox, Lucas C; Alisic, Laura; Ghattas, Omar

2010-08-27

Plate tectonics is regulated by driving and resisting forces concentrated at plate boundaries, but observationally constrained high-resolution models of global mantle flow remain a computational challenge. We capitalized on advances in adaptive mesh refinement algorithms on parallel computers to simulate global mantle flow by incorporating plate motions, with individual plate margins resolved down to a scale of 1 kilometer. Back-arc extension and slab rollback are emergent consequences of slab descent in the upper mantle. Cold thermal anomalies within the lower mantle couple into oceanic plates through narrow high-viscosity slabs, altering the velocity of oceanic plates. Viscous dissipation within the bending lithosphere at trenches amounts to approximately 5 to 20% of the total dissipation through the entire lithosphere and mantle.

Scattering of hydrogen, nitrogen and water ions from micro pore optic plates for application in spaceborne plasma instrumentation

NASA Astrophysics Data System (ADS)

Stude, Joan; Wieser, Martin; Barabash, Stas

2016-10-01

Time-of-flight mass spectrometers for upcoming space missions into enhanced radiation environments need to be small, light weight and energy efficient. Time-of-flight systems using surface interactions as start-event generation can be smaller than foil-type instruments. Start surfaces for such applications need to provide narrow angular scattering, high ionization yields and high secondary electron emissions to be effective. We measured the angular scattering, energy distribution and positive ionization yield of micro pore optics for incident hydrogen, nitrogen and water ions at 2 keV. Positive ionization yields of 2% for H+ , 0.5% for N+ and 0.2% for H2O+ were detected.

Excitation of a Parallel Plate Waveguide by an Array of Rectangular Waveguides

NASA Technical Reports Server (NTRS)

Rengarajan, Sembiam

2011-01-01

This work addresses the problem of excitation of a parallel plate waveguide by an array of rectangular waveguides that arises in applications such as the continuous transverse stub (CTS) antenna and dual-polarized parabolic cylindrical reflector antennas excited by a scanning line source. In order to design the junction region between the parallel plate waveguide and the linear array of rectangular waveguides, waveguide sizes have to be chosen so that the input match is adequate for the range of scan angles for both polarizations. Electromagnetic wave scattered by the junction of a parallel plate waveguide by an array of rectangular waveguides is analyzed by formulating coupled integral equations for the aperture electric field at the junction. The integral equations are solved by the method of moments. In order to make the computational process efficient and accurate, the method of weighted averaging was used to evaluate rapidly oscillating integrals encountered in the moment matrix. In addition, the real axis spectral integral is evaluated in a deformed contour for speed and accuracy. The MoM results for a large finite array have been validated by comparing its reflection coefficients with corresponding results for an infinite array generated by the commercial finite element code, HFSS. Once the aperture electric field is determined by MoM, the input reflection coefficients at each waveguide port, and coupling for each polarization over the range of useful scan angles, are easily obtained. Results for the input impedance and coupling characteristics for both the vertical and horizontal polarizations are presented over a range of scan angles. It is shown that the scan range is limited to about 35 for both polarizations and therefore the optimum waveguide is a square of size equal to about 0.62 free space wavelength.

Graphene-based supercapacitors in the parallel-plate electrode configuration: ionic liquids versus organic electrolytes.

PubMed

Shim, Youngseon; Kim, Hyung J; Jung, Younjoon

2012-01-01

Supercapacitors with two single-sheet graphene electrodes in the parallel plate geometry are studied via molecular dynamics (MD) computer simulations. Pure 1-ethyl-3-methylimidazolium tetrafluoroborate (EMI+BF4-) and a 1.1 M solution of EMI+BF4- in acetonitrile are considered as prototypes of room-temperature ionic liquids (RTILs) and organic electrolytes. Electrolyte structure, charge density and associated electric potential are investigated by varying the charges and separation of the two electrodes. Multiple charge layers formed in the electrolytes in the vicinity of the electrodes are found to screen the electrode surface charge almost completely. As a result, the supercapacitors show nearly an ideal electric double layer behavior, i.e., the electric potential exhibits essentially a plateau behavior in the entire electrolyte region except for sharp changes in screening zones very close to the electrodes. Due to its small size and large charge separation, BF4- is considerably more efficient in shielding electrode charges than EMI+. In the case of the acetonitrile solution, acetonitrile also plays an important role by aligning its dipoles near the electrodes; however, the overall screening mainly arises from ions. Because of the disparity of shielding efficiency between cations and anions, the capacitance of the positively-charged anode is significantly larger than that of the negatively-charged cathode. Therefore, the total cell capacitance in the parallel plate configuration is primarily governed by the cathode. Ion conductivity obtained via the Green-Kubo (GK) method is found to be largely independent of the electrode surface charge. Interestingly, EMI+BF4- shows higher GK ion conductivity than the 1.1 M acetonitrile solution between two parallel plate electrodes.

Thermal Creep Force: Analysis And Application

DTIC Science & Technology

2016-06-01

University Press, 1952. [18] Y. H. Kuo, “On the flow of an incompressible viscous fluid past a flat plate at moderate Reynolds numbers,” The Journal of...observed [19]. Thus, for uniform flow past a flat plate the Stokes drag force on both sides of the plate is 212 5.91 , 2D D F U C LW U Lρ µ...immersed bodies,” A.I.Ch.E. Journal , vol. 7, no. 1, pp. 20–25, 1961. [20] Z. Janour, Resistance of a Plate in Parallel Flow at Low Reynolds Numbers

Atomic physics effects on tokamak edge drift-tearing modes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hahm, T.S.

1993-03-01

The effects of ionization and charge exchange on the linear stability of drift-tearing modes are analytically investigated. In particular, the linear instability threshold {Delta}{sup Th}, produced by ion sound wave coupling is modified. In the strongly collisional regime, the ionization breaks up the near cancellation of the perturbed electric field and the pressure gradient along the magnetic field, and increases the threshold. In the semi-collisional regime, both ionization and charge exchange act as drag on the ion parallel velocity, and consequently decrease the threshold by reducing the effectiveness of ion sound wave propagation.

Atomic physics effects on tokamak edge drift-tearing modes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hahm, T.S.

1993-03-01

The effects of ionization and charge exchange on the linear stability of drift-tearing modes are analytically investigated. In particular, the linear instability threshold [Delta][sup Th], produced by ion sound wave coupling is modified. In the strongly collisional regime, the ionization breaks up the near cancellation of the perturbed electric field and the pressure gradient along the magnetic field, and increases the threshold. In the semi-collisional regime, both ionization and charge exchange act as drag on the ion parallel velocity, and consequently decrease the threshold by reducing the effectiveness of ion sound wave propagation.

Ionization and current growth in N/sub 2/ at very high electric field to gas density ratios

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gylys, V.T.; Jelenkovic, B.M.; Phelps, A.V.

1989-05-01

Measurements and analyses have been made of electron impact ionization and of current growth in pulsed, low-current, prebreakdown discharges in parallel-plane geometry in N/sub 2/ at very high electric field to gas density ratios E/n and low products of the gas density n and electrode separation d. The E/n range and nd ranges were 1

A MEMS Multi-Cantilever Variable Capacitor On Metamaterial

DTIC Science & Technology

2009-03-26

tuning range [38]. 21 Bakri- Kassem and Mansour [39] have developed a parallel-plate variable capac- itor with carrier beams between the plates to...downwards, however, the carrier beams slightly bend down with the movable plate, still prevent- ing it from pulling-in. Bakri- Kassem and Mansour’s... Kassem and R. R. Mansour, “A high-tuning-range mems variable ca- pacitor using carrier beams,” Canadian Journal of Electrical and Computer En- gineering

Tapered-Tip Capillary Electrophoresis Nano-Electrospray Ionization Mass Spectrometry for Ultrasensitive Proteomics: the Mouse Cortex

NASA Astrophysics Data System (ADS)

Choi, Sam B.; Zamarbide, Marta; Manzini, M. Chiara; Nemes, Peter

2017-04-01

Ultrasensitive characterization of the proteome raises the potential to understand how differential gene expression orchestrates cell heterogeneity in the brain. Here, we report a microanalytical capillary electrophoresis nano-flow electrospray ionization (CE-nanoESI) interface for mass spectrometry to enable the measurement of limited amounts of proteins in the mouse cortex. Our design integrates a custom-built CE system to a tapered-tip metal emitter in a co-axial sheath-flow configuration. This interface can be constructed in <15 min using readily available components, facilitating broad adaptation. Tapered-tip CE-nanoESI generates stable electrospray by reproducibly anchoring the Taylor cone, minimizes sample dilution in the ion source, and ensures efficient ion generation by sustaining the cone-jet spraying regime. Parallel reaction monitoring provided a 260-zmol lower limit of detection for angiotensin II (156,000 copies). CE was able to resolve a complex mixture of peptides in 330,000 theoretical plates and identify 15 amol ( 1 pg) of BSA or cytochrome c. Over 30 min of separation, 1 ng protein digest from the mouse cortex yielded 217 nonredundant proteins encompassing a 3-log-order concentration range using a quadrupole time-of-flight mass spectrometer. Identified proteins included many products from genes that are traditionally used to mark oligodendrocytes, astrocytes, and microglia. Finally, key proteins involved in neurodegenerative disorders were detected (e.g., parkinsonism and spastic paraplegia). CE-nanoESI-HRMS delivers sufficient sensitivity to detect proteins in limited amounts of tissues and cell populations to help understand how gene expression differences maintain cell heterogeneity in the brain.

Performance characteristics of mobile MOSFET dosimeter for kilovoltage X-rays used in image guided radiotherapy

PubMed Central

Kumar, A. Sathish; Singh, I. Rabi Raja; Sharma, S. D.; Ravindran, B. Paul

2015-01-01

The main objective of this study was to investigate the characteristics of metal oxide semiconductor field effect transistor (MOSFET) dosimeter for kilovoltage (kV) X-ray beams in order to perform the in vivo dosimetry during image guidance in radiotherapy. The performance characteristics of high sensitivity MOSFET dosimeters were investigated for 80, 90, 100, 110, 120, and 125 kV X-ray beams used for imaging in radiotherapy. This study was performed using Clinac 2100 C/D medical electron linear accelerator with on-board imaging and kV cone beam computed tomography system. The characteristics studied in this work include energy dependence, angular dependence, and linearity. The X-ray beam outputs were measured as per American Association of Physicists in Medicine (AAPM) TG 61 recommendations using PTW parallel plate (PP) ionization chamber, which was calibrated in terms of air kerma (Nk) by the National Standard Laboratory. The MOSFET dosimeters were calibrated against the PP ionization chamber for all the kV X-ray beams and the calibration coefficient was found to be 0.11 cGy/mV with a standard deviation of about ±1%. The response of MOSFET was found to be energy independent for the kV X-ray energies used in this study. The response of the MOSFET dosimeter was also found independent of angle of incidence for the gantry angles in the range of 0° to 360° in-air as well as at 3 cm depth in tissue equivalent phantom. PMID:26500397

Ionospheric plasma flow about a system of electrically biased flat plates. M.S. Thesis - Cleveland State Univ. Final Report

NASA Technical Reports Server (NTRS)

Herr, Joel L.

1993-01-01

The steady state interaction of two electrically biased parallel plates immersed in a flowing plasma characteristic of low earth orbit is studied numerically. Fluid equations are developed to describe the motion of the cold positively charged plasma ions, and are solved using finite-differences in two dimensions on a Cartesian grid. The behavior of the plasma electrons is assumed to be described by the Maxwell-Boltzmann distribution. Results are compared to an analytical and a particle simulation technique for a simplified flow geometry consisting of a single semi-infinite negatively biased plate. Comparison of the extent of the electrical disturbance into the flowing plasma and the magnitude of the current collected by the plate is very good. The interaction of two equally biased parallel plates is studied as a function of applied potential. The separation distance at which the current collected by either plate decreases by five and twenty percent is determined as a function of applied potential. The percent decreases were based on a non-interacting case. The decrease in overall current is caused by a decrease in ionic density in the region between the plates. As the separation between the plates decreases, the plates collect the ions at a faster rate than they are supplied to the middle region by the oncoming plasma flow. The docking of spacecraft in orbit is simulated by moving two plates of unequal potential toward one another in a quasi-static manner. One plate is held at a large negative potential while the other floats electrically in the resulting potential field. It is found that the floating plate does not charge continuously negative as it approaches the other more negatively biased plate. Instead, it charges more and then less negative as ionic current decreases and then increases respectively upon approach. When the two plates come into contact, it is expected that the electrically floating plate will charge rapidly negative to a potential near that of the other plate.

An experimental setup for study direct charge battery based on Sr-90

NASA Astrophysics Data System (ADS)

Özkeçeci, S.; Koç, R.

2017-02-01

In this paper we present construction and analysis of nuclear micro battery driven by Strontium 90 (Sr-90). Our design based on charge deposition on the plates of a capacitor and polarization of dielectric materials between the plates. In the construction we have used liquid Sr-90 with activity 100 mCi in cylindrical ampoule coiled up by thin film graphene as one plate and Manganase dioxide (MnO2) as other plate of the capacitor. A dielectric material (paper) is inserted between the plates. The high energetic beta particles from the Sr-90 penetrate graphene to produce ionization and then electrons are removed from graphene to dielectric material. Electrons inside the dielectric material cause polarization of dipoles. Consequently the radiation from the isotope produces an external current. We discuss effect of beta particles on dielectrics and electrodes beside advantage and disadvantage of a battery of this type.

Ionization chamber dosimeter

DOEpatents

Renner, Tim R.; Nyman, Mark A.; Stradtner, Ronald

1991-01-01

A method for fabricating an ion chamber dosimeter collecting array of the type utilizing plural discrete elements formed on a uniform collecting surface which includes forming a thin insulating layer over an aperture in a frame having surfaces, forming a predetermined pattern of through holes in the layer, plating both surfaces of the layer and simultaneously tilting and rotating the frame for uniform plate-through of the holes between surfaces. Aligned masking and patterned etching of the surfaces provides interconnects between the through holes and copper leads provided to external circuitry.

The transference of heat from a hot plate to an air stream

NASA Technical Reports Server (NTRS)

Elias, Franz

1931-01-01

The object of the present study was to define experimentally the field of temperature and velocity in a heated flat plate when exposed to an air stream whose direction is parallel to it, then calculate therefrom the heat transference and the friction past the flat plate, and lastly, compare the test data with the mathematical theory. To ensure comparable results, we were to actually obtain or else approximate: a) two-dimensional flow; b) constant plate temperature in the direction of the stream. To approximate the flow in two dimensions, we chose a relatively wide plate and measured the velocity and temperature in the median plane.

Omnidirectional antenna having constant phase

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sena, Matthew

Various technologies presented herein relate to constructing and/or operating an antenna having an omnidirectional electrical field of constant phase. The antenna comprises an upper plate made up of multiple conductive rings, a lower ground-plane plate, a plurality of grounding posts, a conical feed, and a radio frequency (RF) feed connector. The upper plate has a multi-ring configuration comprising a large outer ring and several smaller rings of equal size located within the outer ring. The large outer ring and the four smaller rings have the same cross-section. The grounding posts ground the upper plate to the lower plate while maintainingmore » a required spacing/parallelism therebetween.« less

Modeling of composite beams and plates for static and dynamic analysis

NASA Technical Reports Server (NTRS)

Hodges, Dewey H.; Atilgan, Ali R.; Lee, Bok Woo

1990-01-01

A rigorous theory and corresponding computational algorithms was developed for a variety of problems regarding the analysis of composite beams and plates. The modeling approach is intended to be applicable to both static and dynamic analysis of generally anisotropic, nonhomogeneous beams and plates. Development of a theory for analysis of the local deformation of plates was the major focus. Some work was performed on global deformation of beams. Because of the strong parallel between beams and plates, the two were treated together as thin bodies, especially in cases where it will clarify the meaning of certain terminology and the motivation behind certain mathematical operations.

A simple method to ensure proper screw position and plate size selection using the Morscher cervical spine locking plate. Technical note.

PubMed

Ball, P A; Benzel, E C; Baldwin, N G

1994-04-01

The use of bone plate instrumentation with screw fixation has proved to be a useful adjunctive measure in anterior cervical spine fusion surgery. Proper fitting, positioning, and attachment of this instrumentation have been shown to be frequently suboptimal if done without radiographic guidance. The most commonly used method of radiographic assistance for placement of this instrumentation is fluoroscopy. While this gives satisfactory technical results, it is expensive and time-consuming, and exposes the patient and the operating room personnel to ionizing radiation. The authors present a simple technique to ensure screw placement and plate fitting using Kirschner wires and a single lateral radiograph. This technique saves time, reduces exposure to radiation, and has led to satisfactory results in over 20 operative cases.

Generation and investigation of terahertz Airy beam realized using parallel-plate waveguides

NASA Astrophysics Data System (ADS)

Wu, Mengru; Lang, Tingting; Shi, Guohua; Han, Zhanghua

2018-03-01

In this paper, the launching of Airy beam in the terahertz region using waveguiding structures was proposed, designed and numerically characterized. By properly designing the waveguide slit width and the packing number in different sections of parallel-plate waveguides (PPWGs) array, arbitrary phase delay and lateral position-dependent amplitude transmission through the structure, required to realize the target Airy beam profile, can be easily fulfilled. Airy beams working at the frequency of 0.3 THz with good non-diffracting, self-bending, and self-healing features are demonstrated. This study represents a new alternative to scattering-based metasurface structures, and can be utilized in many modern applications.

Analytical theory of coherent synchrotron radiation wakefield of short bunches shielded by conducting parallel plates

NASA Astrophysics Data System (ADS)

Stupakov, Gennady; Zhou, Demin

2016-04-01

We develop a general model of coherent synchrotron radiation (CSR) impedance with shielding provided by two parallel conducting plates. This model allows us to easily reproduce all previously known analytical CSR wakes and to expand the analysis to situations not explored before. It reduces calculations of the impedance to taking integrals along the trajectory of the beam. New analytical results are derived for the radiation impedance with shielding for the following orbits: a kink, a bending magnet, a wiggler of finite length, and an infinitely long wiggler. All our formulas are benchmarked against numerical simulations with the CSRZ computer code.

Rapid viscosity measurements of powdered thermosetting resins

NASA Technical Reports Server (NTRS)

Price, H. L.; Burks, H. D.; Dalal, S. K.

1978-01-01

A rapid and inexpensive method of obtaining processing-related data on powdered thermosetting resins has been investigated. The method involved viscosity measurements obtained with a small specimen (less than 100 mg) parallel plate plastometer. A data acquisition and reduction system was developed which provided a value of viscosity and strain rate about 12-13 second intervals during a test. The effects of specimen compaction pressure and reduction of adhesion between specimen and parallel plates were examined. The plastometer was used to measure some processing-related viscosity changes of an addition polyimide resin, including changes caused by pre-test heat treatment, test temperature, and strain rate.

Investigation of the charging characteristics of micrometer sized droplets based on parallel plate capacitor model.

PubMed

Zhang, Yanzhen; Liu, Yonghong; Wang, Xiaolong; Shen, Yang; Ji, Renjie; Cai, Baoping

2013-02-05

The charging characteristics of micrometer sized aqueous droplets have attracted more and more attentions due to the development of the microfluidics technology since the electrophoretic motion of a charged droplet can be used as the droplet actuation method. This work proposed a novel method of investigating the charging characteristics of micrometer sized aqueous droplets based on parallel plate capacitor model. With this method, the effects of the electric field strength, electrolyte concentration, and ion species on the charging characteristics of the aqueous droplets was investigated. Experimental results showed that the charging characteristics of micrometer sized droplets can be investigated by this method.

Analytical theory of coherent synchrotron radiation wakefield of short bunches shielded by conducting parallel plates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stupakov, Gennady; Zhou, Demin

2016-04-21

We develop a general model of coherent synchrotron radiation (CSR) impedance with shielding provided by two parallel conducting plates. This model allows us to easily reproduce all previously known analytical CSR wakes and to expand the analysis to situations not explored before. It reduces calculations of the impedance to taking integrals along the trajectory of the beam. New analytical results are derived for the radiation impedance with shielding for the following orbits: a kink, a bending magnet, a wiggler of finite length, and an infinitely long wiggler. All our formulas are benchmarked against numerical simulations with the CSRZ computer code.

Wakefield computations for a corrugated pipe as a beam dechirper for FEL applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ng, C. K.; Bane, K. L.F.

A beam “dechirper” based on a corrugated, metallic vacuum chamber has been proposed recently to cancel residual energy chirp in a beam before it enters the undulator in a linac-based X-ray FEL. Rather than the round geometry that was originally proposed, we consider a pipe composed of two parallel plates with corrugations. The advantage is that the strength of the wake effect can be tuned by adjusting the separation of the plates. The separation of the plates is on the order of millimeters, and the corrugations are fractions of a millimeter in size. The dechirper needs to be meters longmore » in order to provide sufficient longitudinal wakefield to cancel the beam chirp. Considerable computation resources are required to determine accurately the wakefield for such a long structure with small corrugation gaps. Combining the moving window technique and parallel computing using multiple processors, the time domain module in the parallel finite-element electromagnetic suite ACE3P allows efficient determination of the wakefield through convergence studies. In this paper, we will calculate the longitudinal, dipole and quadrupole wakefields for the dechirper and compare the results with those of analytical and field matching approaches.« less

The electrical MHD and Hall current impact on micropolar nanofluid flow between rotating parallel plates

NASA Astrophysics Data System (ADS)

Shah, Zahir; Islam, Saeed; Gul, Taza; Bonyah, Ebenezer; Altaf Khan, Muhammad

2018-06-01

The current research aims to examine the combined effect of magnetic and electric field on micropolar nanofluid between two parallel plates in a rotating system. The nanofluid flow between two parallel plates is taken under the influence of Hall current. The flow of micropolar nanofluid has been assumed in steady state. The rudimentary governing equations have been changed to a set of differential nonlinear and coupled equations using suitable similarity variables. An optimal approach has been used to acquire the solution of the modelled problems. The convergence of the method has been shown numerically. The impact of the Skin friction on velocity profile, Nusslet number on temperature profile and Sherwood number on concentration profile have been studied. The influences of the Hall currents, rotation, Brownian motion and thermophoresis analysis of micropolar nanofluid have been mainly focused in this work. Moreover, for comprehension the physical presentation of the embedded parameters that is, coupling parameter N1 , viscosity parameter Re , spin gradient viscosity parameter N2 , rotating parameter Kr , Micropolar fluid constant N3 , magnetic parameter M , Prandtl number Pr , Thermophoretic parameter Nt , Brownian motion parameter Nb , and Schmidt number Sc have been plotted and deliberated graphically.

Reducing/Eliminating ESD Hazards During Pyro Operations

NASA Technical Reports Server (NTRS)

Soriano, Jose Francisco; Kelley, J. D. (Technical Monitor)

2001-01-01

Several safety concerns have occurred during pyro operations at 30% or lower RH in the OPF area based on the increase of electrostatic discharge (ESD). These concerns targeted the safety of personnel, flight hardware, and ground support equipment (GSE). Two proposed methods considered to control ESDs during pyro operations at 30% or lower RH are the use of an ionizer blower and to increase the moisture content. In order to demonstrate that the ionizer is effective in neutralizing static charge, a series of experimental runs were conducted in the Electrostatics Laboratory located in the Operations & Checkout (O&C) Building at NASA Kennedy Space Center (KSC). The effectiveness of the ionizer blower was evaluated based upon the time lapse of a charged metal plate from initial 1000 to 400 volts. Distance, RH, and angle of attack were studied. A full factorial experiment (2(exp 3) = 8) was conducted. Since we did not have a statistical analysis program, such as SAS, available, calculations were done manually based on the method of ANOVA (Analysis of Variances), but R(exp 2) (fitness of curve) was not obtained. As conjectured, distance was found to be the major influencial variable. Therefore, we concluded that the best possible combination of situations would be to position the ionizer blower as close as possible and facing directly into the charged plate. This scenario resulted in the quickest discharge rate, which would be the most beneficial during pyro operations below 30% RH. The second method of increasing the moisture content in the work environment through a modification of the OPF ECS current configuration appeared to be dependent on budget constraints and currently not planned to be modified. Finally, some recommendations are discussed such as to test the ionizer in an actual field experiment with a mockup pyro connector and a technician with all the NASA KSC Safety-compliant PPE to assess the realistic effectiveness of the ionizer blower.

Tunable THz notch filter with a single groove inside parallel-plate waveguides.

PubMed

Lee, Eui Su; Jeon, Tae-In

2012-12-31

A single groove in a parallel-plate waveguide (PPWG) has been applied to a tunable terahertz (THz) notch filter with a transverse-electromagnetic (TEM) mode. When the air gap between the metal plates of the PPWG is controlled from 60 to 240 μm using a motor controlled translation stage or a piezo-actuator, the resonant frequency of the notch filter is changed from 1.75 up to 0.62 THz, respectively. Therefore, the measured tunable sensitivity of the notch filter increases to 6.28 GHz/μm. The measured resonant frequencies were found to be in good agreement with the calculation using an effective groove depth. Using a finite-difference time-domain (FDTD) simulation, we also demonstrate that the sensitivity of a THz microfluidic sensor can be increased via a small air gap, a narrow groove width, and a deep groove depth.

Constrained ceramic-filled polymer armor

DOEpatents

Sandstrom, D.J.; Calkins, N.C.; Gac, F.D.

1990-11-13

An armor system is disclosed in which a plurality of constraint cells are mounted on a surface of a substrate, which is metal armor plate or a similar tough material, such that the cells almost completely cover the surface of the substrate. Each constraint cell has a projectile-receiving wall parallel to the substrate surface and has sides which are perpendicular to and surround the perimeter of the receiving wall. The cells are mounted such that, in one embodiment, the substrate surface serves as a sixth side or closure for each cell. Each cell has inside of it a plate, termed the front plate, which is parallel to and in contact with substantially all of the inside surface of the receiving wall. The balance of each cell is completely filled with a projectile-abrading material, which is a ceramic material in particulate form dispersed in a polymeric matrix. 5 figs.

Casimir effect for parallel plates in a Friedmann-Robertson-Walker universe

NASA Astrophysics Data System (ADS)

Bezerra de Mello, E. R.; Saharian, A. A.; Setare, M. R.

2017-03-01

We evaluate the Hadamard function, the vacuum expectation values (VEVs) of the field squared and the energy-momentum tensor for a massive scalar field with a general curvature coupling parameter in the geometry of two parallel plates on a spatially flat Friedmann-Robertson-Walker background with a general scale factor. On the plates, the field operator obeys the Robin boundary conditions with the coefficients depending on the scale factor. In all the spatial regions, the VEVs are decomposed into the boundary-free and boundary-induced contributions. Unlike the problem with the Minkowski bulk, in the region between the plates, the normal stress is not homogeneous and does not vanish in the geometry of a single plate. Near the plates, it has different signs for accelerated and decelerated expansions of the Universe. The VEV of the energy-momentum tensor, in addition to the diagonal components, has a nonzero off-diagonal component describing an energy flux along the direction normal to the boundaries. Expressions are derived for the Casimir forces acting on the plates. Depending on the Robin coefficients and on the vacuum state, these forces can be either attractive or repulsive. An important difference from the corresponding result in the Minkowski bulk is that the forces on the separate plates, in general, are different if the corresponding Robin coefficients differ. We give the applications of general results for the class of α vacua in the de Sitter bulk. It is shown that, compared with the Bunch-Davies vacuum state, the Casimir forces for a given α vacuum may change the sign.

Influence of obliquely subducting slab on Pacific-North America shear motion inferred from seismic anisotropy along the Queen Charlotte margin

NASA Astrophysics Data System (ADS)

Cao, L.; Kao, H.; Wang, K.; Wang, Z.

2016-12-01

Haida Gwaii is located along the transpressive Queen Charlotte margin between the Pacific (PA) and North America (NA) plates. The highly oblique relative plate motion is partitioned, with the strike-slip component accommodated by the Queen Charlotte Fault (QCF) and the convergent component by a thrust fault offshore. To understand how the presence of a obliquely subducting slab influences shear deformation of the plate boundary, we investigate mantle anisotropy by analyzing shear-wave splitting of teleseismic SKS phases recorded at 17 seismic stations in and around Haida Gwaii. We used the MFAST program to determine the polarization direction of the fast wave (φ) and the delay time (δt) between the fast and slow phases. The fast directions derived from stations on Haida Gwaii and two stations to the north on the Alaska Panhandle are predominantly margin-parallel (NNW). However, away from the plate boundary, the fast direction transitions to WSW-trending, very oblique or perpendicular to the plate boundary. Because the average delay time of 0.6-2.45 s is much larger than values based on an associated local S phase splitting analysis in the same study area, it is reasonable to infer that most of the anisotropy from our SKS analysis originates from the upper mantle and is associated with lattice-preferred orientation of anisotropic minerals. The margin-parallel fast direction within about 100 km of the QCF (average φ = -40º and δt = 1.2 s) is likely induced by the PA-NA shear motion. The roughly margin-normal fast directions farther away, although more scatterd, are consistent with that previously observed in the NA continent and are attributed to the absolute motion of the NA plate. However, the transition between the two regimes based on our SKS analysis appears to be gradual, suggesting that the plate boundary shear influences a much broader region at mantle depths than would be inferred from the surface trace of the QCF. We think this is due to the presence of a subducted portion of the Pacific plate. Because the slab travels mostly in the strike direction, it is expected to induce margin-parallel shear deformation of the mantle material. This result has importance implications to the geodynamics of transpressive plate margins.

A Model Chemistry Class.

ERIC Educational Resources Information Center

Summerlin, Lee; Borgford, Christie

1989-01-01

Described is an activity which uses a 96-well reaction plate and soda straws to construct a model of the periodic table of the elements. The model illustrates the ionization energies of the various elements. Construction of the model and related concepts are discussed. (CW)

Seismicity of the Earth 1900-2007, Japan and Vicinity

USGS Publications Warehouse

Rhea, Susan; Tarr, Arthur C.; Hayes, Gavin P.; Villaseñor, Antonio; Benz, Harley

2010-01-01

This map shows details of Japan and vicinity not visible in an earlier publication, U.S. Geological Survey Scientific Investigations Map 3064. Japan and its island possessions lie across four major tectonic plates: Pacific plate, North America plate; Eurasia plate; and Philippine Sea plate. The Pacific plate is subducted into the mantle, beneath Hokkaido and northern Honshu, along the eastern margin of the Okhotsk microplate, a proposed subdivision of the North America plate (Bird, 2003). Farther south, the pacific plate is subducted beneath volcanic islands along the eastern margin of the Philippine Sea plate. This 2,200 km-long zone of subduction of the Pacific plate is responsible for the creation of the deep offshore Ogasawara and Japan trenches as well as parallel chains of islands and volcanoes, typical of the Circumpacific island arcs. Similarly, the Philippine Sea plate is itself subducting under the Eurasia plate along a zone, extending from Taiwan to southern Honshu, that comprises the Ryuku Islands and the Nansei-Shonto trench.

Evanescent wave coupling in terahertz waveguide arrays.

PubMed

Reichel, K S; Sakoda, N; Mendis, R; Mittleman, D M

2013-07-15

We study energy transfer among an array of identical finite-width parallel-plate waveguides in close proximity, via evanescent wave coupling of broadband terahertz waves. We observe stronger coupling with larger plate separations and longer propagation paths. This work establishes a platform to investigate new opportunities for THz components and devices based on evanescent wave coupling.

46 CFR 54.05-15 - Weldment toughness tests-procedure qualifications.

Code of Federal Regulations, 2010 CFR

2010-10-01

...) Plate for which Charpy V-notch impact testing is required in the parent material and for which V-notch minima are specified shall similarly have welding procedures qualified for toughness by Charpy V-notch testing. For these tests, the test plates shall be oriented with their final rolling direction parallel to...

Interaction of a Rectangular Jet with a Flat-Plate Placed Parallel to the Flow

NASA Technical Reports Server (NTRS)

Zaman, K. B. M. Q.; Brown, C. A.; Bridges, J. A.

2013-01-01

An experimental study is carried out addressing the flowfield and radiated noise from the interaction of a large aspect ratio rectangular jet with a flat plate placed parallel to but away from the direct path of the jet. Sound pressure level spectra exhibit an increase in the noise levels for both the 'reflected' and 'shielded' sides of the plate relative to the free-jet case. Detailed cross-sectional distributions of flowfield properties obtained by hot-wire anemometry are documented for a low subsonic condition. Corresponding mean Mach number distributions obtained by Pitot-probe surveys are presented for high subsonic conditions. In the latter flow regime and for certain relative locations of the plate, a flow resonance accompanied by audible tones is encountered. Under the resonant condition the jet cross-section experiences an 'axis-switching' and flow visualization indicates the presence of an organized 'vortex street'. The trends of the resonant frequency variation with flow parameters exhibit some similarities to, but also marked differences with, corresponding trends of the well-known edgetone phenomenon.

Heterodyne frequency-domain multispectral diffuse optical tomography of breast cancer in the parallel-plane transmission geometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ban, H. Y.; Kavuri, V. C., E-mail: venk@physics.up

Purpose: The authors introduce a state-of-the-art all-optical clinical diffuse optical tomography (DOT) imaging instrument which collects spatially dense, multispectral, frequency-domain breast data in the parallel-plate geometry. Methods: The instrument utilizes a CCD-based heterodyne detection scheme that permits massively parallel detection of diffuse photon density wave amplitude and phase for a large number of source–detector pairs (10{sup 6}). The stand-alone clinical DOT instrument thus offers high spatial resolution with reduced crosstalk between absorption and scattering. Other novel features include a fringe profilometry system for breast boundary segmentation, real-time data normalization, and a patient bed design which permits both axial and sagittalmore » breast measurements. Results: The authors validated the instrument using tissue simulating phantoms with two different chromophore-containing targets and one scattering target. The authors also demonstrated the instrument in a case study breast cancer patient; the reconstructed 3D image of endogenous chromophores and scattering gave tumor localization in agreement with MRI. Conclusions: Imaging with a novel parallel-plate DOT breast imager that employs highly parallel, high-resolution CCD detection in the frequency-domain was demonstrated.« less

Fuel cell separator plate with bellows-type sealing flanges

DOEpatents

Louis, G.A.

1984-05-29

A fuel cell separator includes a rectangular flat plate having two unitary upper sealing flanges respectively comprising opposite marginal edges of the plate folded upwardly and back on themselves and two lower sealing flanges respectively comprising the other two marginal edges of the plate folded downwardly and back on themselves. Each of the sealing flanges includes a flat wall spaced from the plate and substantially parallel thereto and two accordion-pleated side walls, one of which interconnects the flat wall with the plate and the other of which steps just short of the plate, these side walls affording resilient compressibility to the sealing flange in a direction generally normal to the plane of the plate. Four corner members close the ends of the sealing flanges. An additional resiliently compressible reinforcing member may be inserted in the passages formed by each of the sealing flanges with the plate.

Fuel cell separator plate with bellows-type sealing flanges

DOEpatents

Louis, George A.

1986-08-05

A fuel cell separator includes a rectangular flat plate having two unitary upper sealing flanges respectively comprising opposite marginal edges of the plate folded upwardly and back on themselves and two lower sealing flanges respectively comprising the other two marginal edges of the plate folded downwardly and back on themselves. Each of the sealing flanges includes a flat wall spaced from the plate and substantially parallel thereto and two accordion-pleated side walls, one of which interconnects the flat wall with the plate and the other of which stops just short of the plate, these side walls affording resilient compressibility to the sealing flange in a directiongenerally normal to the plane of the plate. Four corner members close the ends of the sealing flanges. An additional resiliently compressible reinforcing member may be inserted in the passages formed by each of the sealing flanges with the plate.

Utility of Squeeze Flow in the Food Industry

NASA Astrophysics Data System (ADS)

Huang, T. A.

2008-07-01

Squeeze flow for obtaining shear viscosity on Newtonian and non-Newtonian fluids has long been established in the literature. Rotational shear flow using cone/plate, a set of parallel plates, or concentric cylinders all develop wall slip, shear fracture, or instability on food related materials such as peanut butter or mayonnaise. Viscosity data obtained using any one of the above mentioned set-ups is suspect or potentially results in significant error. They are unreliable to support or predict the textural differences perceived by consumer evaluation. RMS-800, from Rheometrics Inc., was employed to conduct the squeezing flow under constant speeds on a set of parallel plates. Viscosity data, over a broad range of shear rates, is compared between Hellmann's real (HRM) and light mayonnaise (HLM). The Consistency and shear-thinning indices, as defined in the Power-Law Model, were determined. HRM exhibits a more pronounced shear-thinning when compared to HLM yet the Consistency of HRM is significantly higher. Sensory evaluation by a trained expert panel ranked that adhesiveness and cohesiveness of HLM are significantly higher. It appears that the degree of shear thinning is one of the key rheological parameters in predicting the above mentioned difference in textural attributes. Error involved in determining viscosity from non-parallelism between two plates can be significant to affect the accuracy of the viscosity, in particular, shear-thinning index. Details are a subject for the next presentation. Nevertheless, the method is proven to be fast, rugged, simple, and reliable. It can be developed as a QC tool.

Surface oxidation under ambient air--not only a fast and economical method to identify double bond positions in unsaturated lipids but also a reminder of proper lipid processing.

PubMed

Zhou, Ying; Park, Hyejung; Kim, Philseok; Jiang, Yan; Costello, Catherine E

2014-06-17

A simple, fast approach elucidated carbon-carbon double bond positions in unsaturated lipids. Lipids were deposited onto various surfaces and the products from their oxidation in ambient air were observed by electrospray ionization (ESI) mass spectrometry (MS). The most common oxidative products, aldehydes, were detected as transformations at the cleaved double bond positions. Ozonides and carboxylic acids were generated in certain lipids. Investigations of the conditions controlling the appearance of these products indicated that the surface oxidation depends on light and ambient air. Since the lipid oxidation was slower in a high concentration of ozone, singlet oxygen appeared to be a parallel oxidant for unsaturated lipids. The 3-hydroxyl group in the sphingoid base of sulfatides offered some protection from oxidation for the Δ4,5-double bond, slowing its oxidation rate relative to that of the isolated double bond in the N-linked fatty acyl chain. Direct sampling by thin-layer chromatography (TLC)-ESI-MS provides a powerful approach to elucidate detailed structural information on biological samples. Co-localization of the starting lipids and their oxidation products after TLC separation allowed assignment of the native unsaturation sites. Phosphatidylserine and N,N-dimethyl phosphatidylethanolamine isomers in a bovine brain total lipid extract were distinguished on the basis of their oxidation products. Meanwhile, the findings reported herein reveal a potential pitfall in the assignment of structures to lipids extracted from TLC plates because of artifactual oxidation after the plate development.

Partial Arc Curvilinear Direct Drive Servomotor

NASA Technical Reports Server (NTRS)

Sun, Xiuhong (Inventor)

2014-01-01

A partial arc servomotor assembly having a curvilinear U-channel with two parallel rare earth permanent magnet plates facing each other and a pivoted ironless three phase coil armature winding moves between the plates. An encoder read head is fixed to a mounting plate above the coil armature winding and a curvilinear encoder scale is curved to be co-axis with the curvilinear U-channel permanent magnet track formed by the permanent magnet plates. Driven by a set of miniaturized power electronics devices closely looped with a positioning feedback encoder, the angular position and velocity of the pivoted payload is programmable and precisely controlled.

High loading uranium fuel plate

DOEpatents

Wiencek, Thomas C.; Domagala, Robert F.; Thresh, Henry R.

1990-01-01

Two embodiments of a high uranium fuel plate are disclosed which contain a meat comprising structured uranium compound confined between a pair of diffusion bonded ductile metal cladding plates uniformly covering the meat, the meat having a uniform high fuel loading comprising a content of uranium compound greater than about 45 Vol. % at a porosity not greater than about 10 Vol. %. In a first embodiment, the meat is a plurality of parallel wires of uranium compound. In a second embodiment, the meat is a dispersion compact containing uranium compound. The fuel plates are fabricated by a hot isostatic pressing process.

CALUTRON RECEIVER

DOEpatents

York, H.F.

1959-07-01

A receiver construction is presented for calutrons having two or more ion sources and an individual receiver unit for each source. Design requirements dictate that the face plate defining the receiver entrance slots be placed at an angle to the approaching beam, which means that ions striking the face plate are likely to be scattcred into the entrance slots of other receivers. According to the present invention, the face plate has a surface provided with parallel ridges so disposed that one side only of each ridge's exposed directly to the ion beam. The scattered ions are directed away from adjacent receivers by the ridges on the lace plate.

A hybrid fluorous monolithic capillary column with integrated nanoelectrospray ionization emitter for determination of perfluoroalkyl acids by nano-liquid chromatography-nanoelectrospray ionization-mass spectrometry/mass spectrometry.

PubMed

Zhang, Haiyang; Ou, Junjie; Wei, Yinmao; Wang, Hongwei; Liu, Zhongshan; Zou, Hanfa

2016-04-01

A hybrid fluorous monolithic column was simply prepared via photo-initiated free radical polymerization of an acrylopropyl polyhedral oligomeric silsesquioxane (acryl-POSS) and a perfluorous monomer (2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoroheptyl acrylate) in UV-transparent fused-silica capillaries within 5min. The physical characterization of hybrid fluorous monolith, including scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, mercury intrusion porosimetry (MIP) and nitrogen adsorption/desorption measurement was performed. Chromatographic performance was also evaluated by capillary liquid chromatography (cLC). Due to the fluorous-fluorous interaction between fluorous monolith and analytes, fluorobenzenes could well be separated, and the column efficiencies reached 86,600-92,500plates/m at the velocity of 0.87mm/s for alkylbenzenes and 51,900-76,000plates/m at the velocity of 1.10mm/s for fluorobenzenes. Meanwhile, an approach to integrate nanoelectrospray ionization (ESI) emitter with hybrid fluorous monolithic column was developed for quantitative determination of perfluoroalkyl acids by nanoHPLC-ESI-MS/MS. The integration design could minimize extracolumn volume, thus excluding undesirable peak broadening and improving separation performance. Copyright © 2016 Elsevier B.V. All rights reserved.

Direct analysis of quaternary alkaloids by in situ reactive desorption corona beam ionization MS.

PubMed

Hou, Yulan; Wu, Tingting; Liu, Yaru; Wang, Hua; Chen, Yingzhuang; Chen, Bo; Sun, Wenjian

2014-10-21

The direct detection of quaternary alkaloids by atmospheric pressure chemical ionization (APCI)-base ambient MS is difficult because of their poor volatility. In this study, a reactive protocol was developed for the in situ determination of quaternary alkaloids using desorption corona beam ionization (DCBI) mass spectrometry (MS). The model compounds of 8 quaternary alkaloids including sanguinarine, chelerythrine, cyclanoline, nitidine, coptisine, jatrorrhizine, berberine, palmatine and 2 tertiary alkaloids including protopine and allocryptopine were investigated in different states such as on a polytetrafluoroethylene (PTFE) plate, in raw herbal materials, and in silica gel. After various reactive reagents were studied, the mixture of saturated aqueous NaOH solution and CH3OH solvent (3 : 7, v/v) was selected as the optimized reactive reagent for the reactive DCBI-MS detection. All the target molecules can be detected with high sensitivity. On a PTFE plate the limits of detection were 0.0795, 0.1060, 0.4860, 0.9665, 0.8879, 0.3987, 0.5557, 0.4591, 0.0889, and 0.1929 mg L(-1) for sanguinarine, chelerythrine, cyclanoline, nitidine, coptisine, jatrorrhizine, berberine, palmatine, protopine, and allocryptopine, respectively. The reactive protocol was also applied to the direct detection of raw herbal materials and thin layer chromatography successfully.

Models of lithosphere and asthenosphere anisotropic structure of the Yellowstone hot spot from shear wave splitting

USGS Publications Warehouse

Waite, Gregory P.; Schutt, D.L.; Smith, Robert B.

2005-01-01

Teleseismic shear wave splitting measured at 56 continuous and temporary seismographs deployed in a 500 km by 600 km area around the Yellowstone hot spot indicates that fast anisotropy in the mantle is parallel to the direction of plate motion under most of the array. The average split time from all stations of 0.9 s is typical of continental stations. There is little evidence for plume-induced radial strain, suggesting that any contribution of gravitationally spreading plume material is undetectably small with respect to the plate motion velocity. Two stations within Yellowstone have splitting measurements indicating the apparent fast anisotropy direction (ϕ) is nearly perpendicular to plate motion. These stations are ∼30 km from stations with ϕ parallel to plate motion. The 70° rotation over 30 km suggests a shallow source of anisotropy; however, split times for these stations are more than 2 s. We suggest melt-filled, stress-oriented cracks in the lithosphere are responsible for the anomalous ϕ orientations within Yellowstone. Stations southeast of Yellowstone have measurements of ϕ oriented NNW to WNW at high angles to the plate motion direction. The Archean lithosphere beneath these stations may have significant anisotropy capable of producing the observed splitting.

Complex Plate Tectonic Features on Planetary Bodies: Analogs from Earth

NASA Astrophysics Data System (ADS)

Stock, J. M.; Smrekar, S. E.

2016-12-01

We review the types and scales of observations needed on other rocky planetary bodies (e.g., Mars, Venus, exoplanets) to evaluate evidence of present or past plate motions. Earth's plate boundaries were initially simplified into three basic types (ridges, trenches, and transform faults). Previous studies examined the Moon, Mars, Venus, Mercury and icy moons such as Europa, for evidence of features, including linear rifts, arcuate convergent zones, strike-slip faults, and distributed deformation (rifting or folding). Yet, several aspects merit further consideration. 1) Is the feature active or fossil? Earth's active mid ocean ridges are bathymetric highs, and seafloor depth increases on either side; whereas, fossil mid ocean ridges may be as deep as the surrounding abyssal plain with no major rift valley, although with a minor gravity low (e.g., Osbourn Trough, W. Pacific Ocean). Fossil trenches have less topographic relief than active trenches (e.g., the fossil trench along the Patton Escarpment, west of California). 2) On Earth, fault patterns of spreading centers depend on volcanism. Excess volcanism reduced faulting. Fault visibility increases as spreading rates slow, or as magmatism decreases, producing high-angle normal faults parallel to the spreading center. At magma-poor spreading centers, high resolution bathymetry shows low angle detachment faults with large scale mullions and striations parallel to plate motion (e.g., Mid Atlantic Ridge, Southwest Indian Ridge). 3) Sedimentation on Earth masks features that might be visible on a non-erosional planet. Subduction zones on Earth in areas of low sedimentation have clear trench -parallel faults causing flexural deformation of the downgoing plate; in highly sedimented subduction zones, no such faults can be seen, and there may be no bathymetric trench at all. 4) Areas of Earth with broad upwelling, such as the North Fiji Basin, have complex plate tectonic patterns with many individual but poorly linked ridge segments and transform faults. These details and scales of features should be considered in planning future surveys of altimetry, reflectance, magnetics, compositional, and gravity data from other planetary bodies aimed at understanding the link between a planet's surface and interior, whether via plate tectonics or other processes.

Transient response of a laminated composite plate

NASA Technical Reports Server (NTRS)

Datta, S. K.; Ju, T. H.; Bratton, R. L.; Shah, A. H.

1992-01-01

Results are presented from an investigation of the effect of layering on transient wave propagation in a laminated cross-ply plate, giving attention to the case of 2D plane strain in the case where a line vertical force is applied on a free surface of the plate; the line may be either parallel or perpendicular to the fibers in a ply. The results are in both the time and frequency domains for the normal stress component in the x direction, at a point on the surface of the plate on which the force is applied. Comparative results are also presented for a homogeneous plate whose properties are the static effective ones, when the number of plies is large.

Large volume flow-through scintillating detector

DOEpatents

Gritzo, Russ E.; Fowler, Malcolm M.

1995-01-01

A large volume flow through radiation detector for use in large air flow situations such as incinerator stacks or building air systems comprises a plurality of flat plates made of a scintillating material arranged parallel to the air flow. Each scintillating plate has a light guide attached which transfers light generated inside the scintillating plate to an associated photomultiplier tube. The output of the photomultiplier tubes are connected to electronics which can record any radiation and provide an alarm if appropriate for the application.

Apparent Paradoxes in Classical Electrodynamics: A Fluid Medium in an Electromagnetic Field

ERIC Educational Resources Information Center

Kholmetskii, A. L.; Yarman, T.

2008-01-01

In this paper we analyse a number of teaching paradoxes of classical electrodynamics, dealing with the relativistic transformation of energy and momentum for a fluid medium in an external electromagnetic field. In particular, we consider a moving parallel plate charged capacitor, where the electric attraction of its plates is balanced by the…

Moisture Determination of Nuts and Dry Fruits using a Capacitance Sensor

USDA-ARS?s Scientific Manuscript database

Impedance (Z), and phase angle (') of a cylindrical parallel-plate capacitor with in-shell peanuts between the plates was measured earlier, using a CI meter (Chari’s Impedance meter), at 1 and 5 MHz . Capacitance C, was derived from Z and ', and using the C, ', and Z values of a set of peanuts whos...

Sensing the Moisture Content of Dry Cherries - A Rapid and Nondestructive Method

USDA-ARS?s Scientific Manuscript database

Impedance (Z), and phase angle (') of a parallel-plate capacitor with a single cherry fruit between the plates was measured using a CI meter (Chari’s Impedance meter), at 1 and 9 MHz . Capacitance C, was derived from Z and ', and using the C, ', and Z values of a set of cherries whose moisture cont...

Standardized performance tests of collectors of solar thermal energy - A flat-plate copper collector with parallel mylar striping

NASA Technical Reports Server (NTRS)

Johnson, S. M.

1976-01-01

Basic test results are reported for a flat plate solar collector whose performance was determined in a solar simulator. The collector was tested over ranges of inlet temperatures, fluxes and one coolant flow rate. Collector efficiency is correlated in terms of inlet temperature and flux level.

Breast cancer risk from low-dose exposures to ionizing radiation: results of parallel analysis of three exposed populations of women

DOE Office of Scientific and Technical Information (OSTI.GOV)

Land, C.E.; Boice, J.D. Jr.; Shore, R.E.

1980-08-01

Breast cancer incidence data were analyzed from three populations of women exposed to ionizing radiation: survivors of the Hiroshima and Nagasaki atomic bombs, patients in Massachusetts tuberculosis sanitoria who were exposed to multiple chest fluoroscopies, and patients treated by X-rays for acute postpartum mastitis in Rochester, New York. Parallel analyses by radiation dose, age at exposure, and time after exposure suggested that risk of radiation-induced cancer increased approximately linearly with increasing dose and was heavily dependent on age at exposure; however, the risk was otherwise remarkably similar among the three populations, at least for ages 10 to 40 years atmore » exposure, and followed the same temporal pattern of occurrence as did breast cancer incidence in nonexposed women of similar ages.« less

Analytical theory of coherent synchrotron radiation wakefield of short bunches shielded by conducting parallel plates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stupakov, Gennady; Zhou, Demin

2016-04-21

We develop a general model of coherent synchrotron radiation (CSR) impedance with shielding provided by two parallel conducting plates. This model allows us to easily reproduce all previously known analytical CSR wakes and to expand the analysis to situations not explored before. It reduces calculations of the impedance to taking integrals along the trajectory of the beam. New analytical results are derived for the radiation impedance with shielding for the following orbits: a kink, a bending magnet, a wiggler of finite length, and an infinitely long wiggler. Furthermore, all our formulas are benchmarked against numerical simulations with the CSRZ computermore » code.« less

Large-scale trench-normal mantle flow beneath central South America

NASA Astrophysics Data System (ADS)

Reiss, M. C.; Rümpker, G.; Wölbern, I.

2018-01-01

We investigate the anisotropic properties of the fore-arc region of the central Andean margin between 17-25°S by analyzing shear-wave splitting from teleseismic and local earthquakes from the Nazca slab. With partly over ten years of recording time, the data set is uniquely suited to address the long-standing debate about the mantle flow field at the South American margin and in particular whether the flow field beneath the slab is parallel or perpendicular to the trench. Our measurements suggest two anisotropic layers located within the crust and mantle beneath the stations, respectively. The teleseismic measurements show a moderate change of fast polarizations from North to South along the trench ranging from parallel to subparallel to the absolute plate motion and, are oriented mostly perpendicular to the trench. Shear-wave splitting measurements from local earthquakes show fast polarizations roughly aligned trench-parallel but exhibit short-scale variations which are indicative of a relatively shallow origin. Comparisons between fast polarization directions from local earthquakes and the strike of the local fault systems yield a good agreement. To infer the parameters of the lower anisotropic layer we employ an inversion of the teleseismic waveforms based on two-layer models, where the anisotropy of the upper (crustal) layer is constrained by the results from the local splitting. The waveform inversion yields a mantle layer that is best characterized by a fast axis parallel to the absolute plate motion which is more-or-less perpendicular to the trench. This orientation is likely caused by a combination of the fossil crystallographic preferred orientation of olivine within the slab and entrained mantle flow beneath the slab. The anisotropy within the crust of the overriding continental plate is explained by the shape-preferred orientation of micro-cracks in relation to local fault zones which are oriented parallel to the overall strike of the Andean range. Our results do not provide any evidence for a significant contribution of trench-parallel mantle flow beneath the subducting slab.

[Morphology determination of multi-needle-to-plate positive corona discharge].

PubMed

Su, Peng-hao; Zhu, Yi-min; Chen, Hai-feng

2008-09-01

Using the method of OES (optical emission spectrum) for measuring N2 emission spectrum, the distribution of the energetic electrons in multi-needle-to-plate positive corona discharge at atmospheric pressure was investigated, and compared with that in negative corona discharge. According to the distribution of N2 second positive band's intensity I(SPB), the outline of the ionization region in glow discharge and the streamer channel were drawn rather accurately. The relationship between I(SPB) and the discharge current I in glow discharge can be obtained through the volume integral of the I(SPB). In glow discharge, both the ionization region scale and I(SPB) are smaller than in negative corona discharge, the electron avalanche develops farther along the radius direction of needle than along axis direction, and only the arrange along axis direction is enhanced slightly with the rise of the applied voltage U. The integral of I(SPB) is second order linear to I. In streamer discharge, the discharge channels develop from needlepoint to the plate, while the shape of the region in which I(SPB) is higher looks like a bullet. The density of energetic electron in the channel farther away from the needlepoint is relatively uniform along the axis direction, but first increases then decreases along the radius direction.

Shockwave compression of Ar gas at several initial densities

NASA Astrophysics Data System (ADS)

Dattelbaum, Dana M.; Goodwin, Peter M.; Garcia, Daniel B.; Gustavsen, Richard L.; Lang, John M.; Aslam, Tariq D.; Sheffield, Stephen A.; Gibson, Lloyd L.; Morris, John S.

2017-01-01

Experimental data of the principal Hugoniot locus of variable density gas-phase noble and molecular gases are rare. The majority of shock Hugoniot data is either from shock tube experiments on low-pressure gases or from plate impact experiments on cryogenic, liquefied gases. In both cases, physics regarding shock compressibility, thresholds for the on-set of shock-driven ionization, and even dissociation chemistry are difficult to infer for gases at intermediate densities. We have developed an experimental target design for gas gun-driven plate impact experiments on noble gases at initial pressures between 200-1000 psi. Using optical velocimetry, we are able to directly determine both the shock and particle velocities of the gas on the principal Hugoniot locus, as well as clearly differentiate ionization thresholds. The target design also results in multiply shocking the gas in a quasi-isentropic fashion yielding off-Hugoniot compression data. We describe the results of a series of plate impact experiments on Ar with starting densities between 0.02-0.05 g/cm3 at room temperature. Furthermore, by coupling optical fibers to the targets, we have measured the time-resolved optical emission from the shocked gas using a spectrometer coupled to an optical streak camera to spectrally-resolve the emission, and with a 5-color optical pyrometer for temperature determination.

Device for calibrating a radiation detector system

DOEpatents

McFee, M.C.; Kirkham, T.J.; Johnson, T.H.

1994-12-27

A device is disclosed for testing a radiation detector system that includes at least two arrays of radiation detectors that are movable with respect to each other. The device includes a ''shield plate'' or shell, and an opposing ''source plate'' containing a source of ionizing radiation. Guides are attached to the outer surface of the shell for engaging the forward ends of the detectors, thereby reproducibly positioning the detectors with respect to the source and with respect to each other, thereby ensuring that a predetermined portion of the radiation emitted by the source passes through the shell and reaches the detectors. The shell is made of an hydrogenous material having approximately the same radiological attenuation characteristics as composite human tissue. The source represents a human organ such as the lungs, heart, kidneys, liver, spleen, pancreas, thyroid, testes, prostate, or ovaries. The source includes a source of ionizing radiation having a long half-life and an activity that is within the range typically searched for in human subjects. 3 figures.

Device for calibrating a radiation detector system

DOEpatents

Mc Fee, Matthew C.; Kirkham, Tim J.; Johnson, Tippi H.

1994-01-01

A device for testing a radiation detector system that includes at least two arrays of radiation detectors that are movable with respect to each other. The device includes a "shield plate" or shell, and an opposing "source plate" containing a source of ionizing radiation. Guides are attached to the outer surface of the shell for engaging the forward ends of the detectors, thereby reproducibly positioning the detectors with respect to the source and with respect to each other, thereby ensuring that a predetermined portion of the radiation emitted by the source passes through the shell and reaches the detectors. The shell is made of an hydrogenous material having approximately the same radiological attenuation characteristics as composite human tissue. The source represents a human organ such as the lungs, heart, kidneys, heart, liver, spleen, pancreas, thyroid, testes, prostate, or ovaries. The source includes a source of ionizing radiation having a long half-life and an activity that is within the range typically searched for in human subjects.

How do long-offset oceanic transforms adapt to plate motion changes? The example of the Western Pacific-Antarctic plate boundary

NASA Astrophysics Data System (ADS)

Lodolo, Emanuele; Coren, Franco; Ben-Avraham, Zvi

2013-03-01

Oceanic transform faults respond to changes in the direction of relative plate motion. Studies have shown that short-offset transforms generally adjust with slight bends near the ridge axis, while long-offset ones have a remarkably different behavior. The western Pacific-Antarctic plate boundary highlights these differences. A set of previously unpublished seismic profiles, in combination with magnetic anomaly identifications, shows how across a former, ~1250 km long transform (the Emerald Fracture Zone), plate motion changes have produced a complex geometric readjustment. Three distinct sections are recognized along this plate boundary: an eastern section, characterized by parallel, multiple fault strand lineaments; a central section, shallower than the rest of the ridge system, overprinted by a mantle plume track; and a western section, organized in a cascade of short spreading axes/transform lineaments. This configuration was produced by changes that occurred since 30 Ma in the Australia-Pacific relative plate motion, combined with a gradual clockwise change in Pacific-Antarctic plate motion. These events caused extension along the former Emerald Fracture Zone, originally linking the Pacific-Antarctic spreading ridge system with the Southeast Indian ridge. Then an intra-transform propagating ridge started to develop in response to a ~6 Ma change in the Pacific-Antarctic spreading direction. The close proximity of the Euler poles of rotation amplified the effects of the geometric readjustments that occurred along the transform system. This analysis shows that when a long-offset transform older than 20 Ma is pulled apart by changes in spreading velocity vectors, it responds with the development of multiple discrete, parallel fault strands, whereas in younger lithosphere, locally modified by thermal anisotropies, tensional stresses generate an array of spreading axes offset by closely spaced transforms.

No spreading across the southern Juan de Fuca ridge axial cleft during 1994-1996

USGS Publications Warehouse

Chadwell, C.D.; Hildebrand, J.A.; Spiess, Fred N.; Morton, J.L.; Normark, W.R.; Reiss, C.A.

1999-01-01

Direct-path acoustic measurements between seafloor transponders observed no significant extension (-10 ?? 14 mm/yr) from August 1994 to September 1996 at the southern Juan de Fuca Ridge (44??40' N and 130??20' W). The acoustic path for the measurement is a 691-m baseline straddling the axial cleft, which bounds the Pacific and Juan de Fuca plates. Given an expected full-spreading rate of 56 mm/yr, these data suggest that extension across this plate boundary occurs episodically within the narrow (~1 km) region of the axial valley floor, and that active deformation is occurring between the axial cleft and the plate interior. A cleft-parallel 714-m baseline located 300 m to the west of the cleft on the Pacific plate monitored system performance and, as expected, observed no motion (+5??7 mm/yr) between the 1994 and 1996 surveys.Direct-path acoustic measurements between seafloor transponders observed no significant extension (-10 ?? 14 mm/yr) from August 1994 to September 1996 at the southern Juan de Fuca Ridge (44??40 minutes N and 130??20 minutes W). The acoustic path for the measurement is a 691-m baseline straddling the axial cleft, which bounds the Pacific and Juan de Fuca plates. Given an expected full-spreading rate of 56 mm/yr, these data suggest that extension across this plate boundary occurs episodically within the narrow (approx. 1 km) region of the axial valley floor, and that active deformation is occurring between the axial cleft and the plate interior. A cleft-parallel 714-m baseline located 300 m to the west of the cleft on the Pacific plate monitored system performance and, as expected, observed no motion (+5 ?? 7 mm/yr) between the 1994 and 1996 surveys.

Application of coordinate transform on ball plate calibration

NASA Astrophysics Data System (ADS)

Wei, Hengzheng; Wang, Weinong; Ren, Guoying; Pei, Limei

2015-02-01

For the ball plate calibration method with coordinate measurement machine (CMM) equipped with laser interferometer, it is essential to adjust the ball plate parallel to the direction of laser beam. It is very time-consuming. To solve this problem, a method based on coordinate transformation between machine system and object system is presented. With the fixed points' coordinates of the ball plate measured in the object system and machine system, the transformation matrix between the coordinate systems is calculated. The laser interferometer measurement data error due to the placement of ball plate can be corrected with this transformation matrix. Experimental results indicate that this method is consistent with the handy adjustment method. It avoids the complexity of ball plate adjustment. It also can be applied to the ball beam calibration.

Measurement of laser activated electron tunneling from semiconductor zinc oxide to adsorbed organic molecules by a matrix assisted laser desorption ionization mass spectrometer.

PubMed

Zhong, Hongying; Fu, Jieying; Wang, Xiaoli; Zheng, Shi

2012-06-04

Measurement of light induced heterogeneous electron transfer is important for understanding of fundamental processes involved in chemistry, physics and biology, which is still challenging by current techniques. Laser activated electron tunneling (LAET) from semiconductor metal oxides was observed and characterized by a MALDI (matrix assisted laser desorption ionization) mass spectrometer in this work. Nanoparticles of ZnO were placed on a MALDI sample plate. Free fatty acids and derivatives were used as models of organic compounds and directly deposited on the surface of ZnO nanoparticles. Irradiation of UV laser (λ=355 nm) with energy more than the band gap of ZnO produces ions that can be detected in negative mode. When TiO(2) nanoparticles with similar band gap but much lower electron mobility were used, these ions were not observed unless the voltage on the sample plate was increased. The experimental results indicate that laser induced electron tunneling is dependent on the electron mobility and the strength of the electric field. Capture of low energy electrons by charge-deficient atoms of adsorbed organic molecules causes unpaired electron-directed cleavages of chemical bonds in a nonergodic pathway. In positive detection mode, electron tunneling cannot be observed due to the reverse moving direction of electrons. It should be able to expect that laser desorption ionization mass spectrometry is a new technique capable of probing the dynamics of electron tunneling. LAET offers advantages as a new ionization dissociation method for mass spectrometry. Copyright © 2012 Elsevier B.V. All rights reserved.

Crustal origin of trench-parallel shear-wave fast polarizations in the Central Andes

NASA Astrophysics Data System (ADS)

Wölbern, I.; Löbl, U.; Rümpker, G.

2014-04-01

In this study, SKS and local S phases are analyzed to investigate variations of shear-wave splitting parameters along two dense seismic profiles across the central Andean Altiplano and Puna plateaus. In contrast to previous observations, the vast majority of the measurements reveal fast polarizations sub-parallel to the subduction direction of the Nazca plate with delay times between 0.3 and 1.2 s. Local phases show larger variations of fast polarizations and exhibit delay times ranging between 0.1 and 1.1 s. Two 70 km and 100 km wide sections along the Altiplano profile exhibit larger delay times and are characterized by fast polarizations oriented sub-parallel to major fault zones. Based on finite-difference wavefield calculations for anisotropic subduction zone models we demonstrate that the observations are best explained by fossil slab anisotropy with fast symmetry axes oriented sub-parallel to the slab movement in combination with a significant component of crustal anisotropy of nearly trench-parallel fast-axis orientation. From the modeling we exclude a sub-lithospheric origin of the observed strong anomalies due to the short-scale variations of the fast polarizations. Instead, our results indicate that anisotropy in the Central Andes generally reflects the direction of plate motion while the observed trench-parallel fast polarizations likely originate in the continental crust above the subducting slab.

Coaxial ion trap mass spectrometer: concentric toroidal and quadrupolar trapping regions.

PubMed

Peng, Ying; Hansen, Brett J; Quist, Hannah; Zhang, Zhiping; Wang, Miao; Hawkins, Aaron R; Austin, Daniel E

2011-07-15

We present the design and results for a new radio-frequency ion trap mass analyzer, the coaxial ion trap, in which both toroidal and quadrupolar trapping regions are created simultaneously. The device is composed of two parallel ceramic plates, the facing surfaces of which are lithographically patterned with concentric metal rings and covered with a thin film of germanium. Experiments demonstrate that ions can be trapped in either region, transferred from the toroidal to the quadrupolar region, and mass-selectively ejected from the quadrupolar region to a detector. Ions trapped in the toroidal region can be transferred to the quadrupole region using an applied ac signal in the radial direction, although it appears that the mechanism of this transfer does not involve resonance with the ion secular frequency, and the process is not mass selective. Ions in the quadrupole trapping region are mass analyzed using dipole resonant ejection. Multiple transfer steps and mass analysis scans are possible on a single population of ions, as from a single ionization/trapping event. The device demonstrates better mass resolving power than the radially ejecting halo ion trap and better sensitivity than the planar quadrupole ion trap.

Measurements of the temperature dependence of radiation induced conductivity in polymeric dielectrics

NASA Astrophysics Data System (ADS)

Gillespie, Jodie

This study measures Radiation Induced Conductivity (RIC) in five insulating polymeric materials over temperatures ranging from ~110 K to ~350 K: polyimide (PI or Kapton HN(TM) and Kapton E(TM)), polytetraflouroethylene (PTFE or Teflon(TM)), ethylene-tetraflouroethylene (ETFE or Tefzel(TM)), and Low Density Polyethylene (LDPE). RIC occurs when incident ionizing radiation deposits energy and excites electrons into the conduction band of insulators. Conductivity was measured when a voltage was applied across vacuum-baked, thin film polymer samples in a parallel plate geometry. RIC was calculated as the difference in sample conductivity under no incident radiation and under an incident ~4 MeV electron beam at low incident dose rates of 0.01 rad/sec to 10 rad/sec. The steady-state RIC was found to agree well with the standard power law relation, sigmaRIC(D˙) = kRIC(T) D˙Delta(T) between conductivity, sigmaRIC and adsorbed dose rate, D˙. Both the proportionality constant, kRIC, and the power, Delta, were found to be temperature-dependent above ~250 K, with behavior consistent with photoconductivity models developed for localized trap states in disordered semiconductors. Below ~250 K, kRIC and Delta exhibited little change in any of the materials.

Low energy, high power hydrogen neutral beam for plasma heating

DOE Office of Scientific and Technical Information (OSTI.GOV)

Deichuli, P.; Davydenko, V.; Ivanov, A., E-mail: ivanov@inp.nsk.su

A high power, relatively low energy neutral beam injector was developed to upgrade of the neutral beam system of the gas dynamic trap device and C2-U experiment. The ion source of the injector produces a proton beam with the particle energy of 15 keV, current of up to 175 A, and pulse duration of a few milliseconds. The plasma emitter of the ion source is produced by superimposing highly ionized plasma jets from an array of four arc-discharge plasma generators. A multipole magnetic field produced with permanent magnets at the periphery of the plasma box is used to increase themore » efficiency and improve the uniformity of the plasma emitter. Multi-slit grids with 48% transparency are fabricated from bronze plates, which are spherically shaped to provide geometrical beam focusing. The focal length of the Ion Optical System (IOS) is 3.5 m and the initial beam diameter is 34 cm. The IOS geometry and grid potentials were optimized numerically to ensure accurate beam formation. The measured angular divergences of the beam are ±0.01 rad parallel to the slits and ±0.03 rad in the transverse direction.« less

Assessment of the Biomechanical Performance of 5 Plating Techniques in Fixation of Mandibular Subcondylar Fracture Using Finite Element Analysis.

PubMed

Darwich, Mhd Ayham; Albogha, Mhd Hassan; Abdelmajeed, Adnan; Darwich, Khaldoun

2016-04-01

The aim of this study was to compare the performances of 5 plating techniques for fixation of unilateral mandibular subcondylar fracture. Five titanium plating techniques for fixation of condylar fracture were analyzed using the finite element method. The modeled techniques were 1) 1 straight plate, 2) 2 parallel straight plates, 3) 2 angulated straight plates, 4) 1 trapezoidal plate, and 5) 1 square plate. Three-dimensional models were generated using patient-specific geometry for the mandible obtained from a computerized tomographic image of a healthy living man. Plates were designed and combined with the mandible and analyzed under a 500-N load. The single straight plate presented the most inferior performance; it presented maximum displacement and strain on cortical bone. The trapezoidal plate induced the least amount of strain on cortical bone and was best at resisting displacement. The trapezoidal plate is recommended for fixation of subcondylar fracture. Copyright © 2016 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

New 2D diffraction model and its applications to terahertz parallel-plate waveguide power splitters

PubMed Central

Zhang, Fan; Song, Kaijun; Fan, Yong

2017-01-01

A two-dimensional (2D) diffraction model for the calculation of the diffraction field in 2D space and its applications to terahertz parallel-plate waveguide power splitters are proposed in this paper. Compared with the Huygens-Fresnel principle in three-dimensional (3D) space, the proposed model provides an approximate analytical expression to calculate the diffraction field in 2D space. The diffraction filed is regarded as the superposition integral in 2D space. The calculated results obtained from the proposed diffraction model agree well with the ones by software HFSS based on the element method (FEM). Based on the proposed 2D diffraction model, two parallel-plate waveguide power splitters are presented. The splitters consist of a transmitting horn antenna, reflectors, and a receiving antenna array. The reflector is cylindrical parabolic with superimposed surface relief to efficiently couple the transmitted wave into the receiving antenna array. The reflector is applied as computer-generated holograms to match the transformed field to the receiving antenna aperture field. The power splitters were optimized by a modified real-coded genetic algorithm. The computed results of the splitters agreed well with the ones obtained by software HFSS verify the novel design method for power splitter, which shows good applied prospects of the proposed 2D diffraction model. PMID:28181514

Finite element analysis of three patterns of internal fixation of fractures of the mandibular condyle.

PubMed

Aquilina, Peter; Chamoli, Uphar; Parr, William C H; Clausen, Philip D; Wroe, Stephen

2013-06-01

The most stable pattern of internal fixation for fractures of the mandibular condyle is a matter for ongoing discussion. In this study we investigated the stability of three commonly used patterns of plate fixation, and constructed finite element models of a simulated mandibular condylar fracture. The completed models were heterogeneous in the distribution of bony material properties, contained about 1.2 million elements, and incorporated simulated jaw-adducting musculature. Models were run assuming linear elasticity and isotropic material properties for bone. This model was considerably larger and more complex than previous finite element models that have been used to analyse the biomechanical behaviour of differing plating techniques. The use of two parallel 2.0 titanium miniplates gave a more stable configuration with lower mean element stresses and displacements over the use of a single miniplate. In addition, a parallel orientation of two miniplates resulted in lower stresses and displacements than did the use of two miniplates in an offset pattern. The use of two parallel titanium plates resulted in a superior biomechanical result as defined by mean element stresses and relative movement between the fractured fragments in these finite element models. Copyright © 2012 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

Alkali metal ionization detector

DOEpatents

Bauerle, James E.; Reed, William H.; Berkey, Edgar

1978-01-01

Variations in the conventional filament and collector electrodes of an alkali metal ionization detector, including the substitution of helical electrode configurations for either the conventional wire filament or flat plate collector; or, the substitution of a plurality of discrete filament electrodes providing an in situ capability for transferring from an operationally defective filament electrode to a previously unused filament electrode without removing the alkali metal ionization detector from the monitored environment. In particular, the helical collector arrangement which is coaxially disposed about the filament electrode, i.e. the thermal ionizer, provides an improved collection of positive ions developed by the filament electrode. The helical filament design, on the other hand, provides the advantage of an increased surface area for ionization of alkali metal-bearing species in a monitored gas environment as well as providing a relatively strong electric field for collecting the ions at the collector electrode about which the helical filament electrode is coaxially positioned. Alternatively, both the filament and collector electrodes can be helical. Furthermore, the operation of the conventional alkali metal ionization detector as a leak detector can be simplified as to cost and complexity, by operating the detector at a reduced collector potential while maintaining the sensitivity of the alkali metal ionization detector adequate for the relatively low concentration of alkali vapor and aerosol typically encountered in leak detection applications.

Discrimination of portraits using a hybrid parallel joint transform correlator system

NASA Astrophysics Data System (ADS)

Inaba, Rieko; Hashimoto, Asako; Kodate, Kashiko

1999-05-01

A hybrid parallel joint transform correlation system is demonstrated through the introduction of a five-channel binary zone plate array and is applied to the discrimination of portraits for a presumed criminal investigation. In order to improve performance, we adopt pe-processing of images with white area of 20%. Furthermore, we discuss the robustness.

Miniature electrometer preamplifier effectively compensates for input capacitance

NASA Technical Reports Server (NTRS)

Burrous, C. N.; Deboo, G. J.

1966-01-01

Negative capacitance preamplifier using a dual MOS /Metal Oxide Silicon/ transistor in conjunction with bipolar transistors is used with intracellular microelectrodes in recording bioelectric potentials. Applications would include use as a pickup plate video amplifier in storage tube tests and for pH and ionization chamber measurements.

Nondestructive Determination of Moisture Content in Dry Fruits by Impedance and Phase angle measurements

USDA-ARS?s Scientific Manuscript database

Impedance (Z), and phase angle (') of a cylindrical parallel-plate capacitor with dry fruits between the plates was measured using a CI meter (Chari’s Impedance meter), at 1 and 9 MHz . Capacitance, C was derived from Z and ', and using the C, ', and Z values of a set of cherries whose moisture con...

Tunable Patch Antennas Using Microelectromechanical Systems

DTIC Science & Technology

2011-05-11

Figure 28, was selected as most suitable to this application. MetalMUMPs is a surface micromachining process with polysilicon , silicon nitride, nickel...yields. MEMS Variable Capacitor Design The MEMS capacitors reported here were an original design that features nickel and polysilicon layers as...the movable plates of a variable parallel plate capacitor. The polysilicon layer was embedded in silicon nitride for electrical isolation and suspended

Electric alignment of plate shaped clay aggregates in oils

NASA Astrophysics Data System (ADS)

Castberg, Rene; Rozynek, Zbigniew; Måløy, Knut Jørgen; Flekkøy, Eirik

2016-01-01

We experimentally investigate the rotation of plate shaped aggregates of clay mineral particles immersed in silicone oil. The rotation is induced by an external electric field. The rotation time is measured as a function of the following parameters: electric field strength, the plate geometry (length and width) and the dielectric properties of the plates. We find that the plates always align with their longest axis parallel to the direction of the electric field (E), independently of the arrangement of individual clay -2 mineral particles within the plate. The rotation time is found to scale as E and is proportional to the viscosity (μ), which coincides well with a model that describes orientation of dipoles in electric fields. As the length of the plate is increased we quantify a difference between the longitudinal and transverse polarisability. Finally, we show that moist plates align faster. We attribute this to the change of the dielectric properties of the plate due to the presence of water.

Seismicity of the Earth 1900-2010 Aleutian arc and vicinity

USGS Publications Warehouse

Benz, Harley M.; Herman, Matthew; Tarr, Arthur C.; Hayes, Gavin P.; Furlong, Kevin P.; Villaseñor, Antonio; Dart, Richard L.; Rhea, Susan

2011-01-01

This map shows details of the Aleutian arc not visible in an earlier publication. The Aleutian arc extends about 3,000 km from the Gulf of Alaska to the Kamchatka Peninsula. It marks the region where the Pacific plate subducts into the mantle beneath the North America plate. This subduction is responsible for the generation of the Aleutian Islands and the deep offshore Aleutian Trench. Relative to a fixed North America plate, the Pacific plate is moving northwest at a rate that increases from about 55 mm per year at the arc's eastern edge to 75 mm per year near its western terminus. In the east, the convergence of the plates is nearly perpendicular to the plate boundary. However, because of the boundary's curvature, as one travels westward along the arc, the subduction becomes more and more oblique to the boundary until the relative plate motion becomes parallel to the arc at the Near Islands near its western edge. Subduction zones such as the Aleutian arc are geologically complex and produce numerous earthquakes from multiple sources. Deformation of the overriding North America plate generates shallow crustal earthquakes, whereas slip at the interface of the plates generates interplate earthquakes that extend from near the base of the trench to depths of 40 to 60 km. At greater depths, Aleutian arc earthquakes occur within the subducting Pacific plate and can reach depths of 300 km. Since 1900, six great earthquakes have occurred along the Aleutian Trench, Alaska Peninsula, and Gulf of Alaska: M8.4 1906 Rat Islands; M8.6 1938 Shumagin Islands; M8.6 1946 Unimak Island; M8.6 1957 Andreanof Islands; M9.2 1964 Prince William Sound; and M8.7 1965 Rat Islands. Several relevant tectonic elements (plate boundaries and active volcanoes) provide a context for the seismicity presented on the main map panel. The plate boundaries are most accurate along the axis of the Aleutian Trench and more diffuse or speculative in extreme northeastern Russia. The active volcanoes parallel the Aleutian Trench from the Gulf of Alaska to the Rat Islands.

Vibration sensors

NASA Astrophysics Data System (ADS)

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

2003-10-01

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

Search for auroral belt E-parallel fields with high-velocity barium ion injections

NASA Technical Reports Server (NTRS)

Heppner, J. P.; Ledley, B. G.; Miller, M. L.; Marionni, P. A.; Pongratz, M. B.

1989-01-01

In April 1984, four high-velocity shaped-charge Ba(+) injections were conducted from two sounding rockets at 770-975 km over northern Alaska under conditions of active auroral and magnetic disturbance. Spatial ionization (brightness) profiles of high-velocity Ba(+) clouds from photometric scans following each release were found to be consistent with the 28-sec theoretical time constant for Ba photoionization determined by Carlsten (1975). These observations therefore revealed no evidence of anomalous fast ionization predicted by the Alfven critical velocity hypothesis.

Parallel Study of HEND, RAD, and DAN Instrument Response to Martian Radiation and Surface Conditions

NASA Technical Reports Server (NTRS)

Martiniez Sierra, Luz Maria; Jun, Insoo; Litvak, Maxim; Sanin, Anton; Mitrofanov, Igor; Zeitlin, Cary

2015-01-01

Nuclear detection methods are being used to understand the radiation environment at Mars. JPL (Jet Propulsion Laboratory) assets on Mars include: Orbiter -2001 Mars Odyssey [High Energy Neutron Detector (HEND)]; Mars Science Laboratory Rover -Curiosity [(Radiation Assessment Detector (RAD); Dynamic Albedo Neutron (DAN))]. Spacecraft have instruments able to detect ionizing and non-ionizing radiation. Instrument response on orbit and on the surface of Mars to space weather and local conditions [is discussed] - Data available at NASA-PDS (Planetary Data System).

Characteristics of a p-Si detector in high energy electron fields.

PubMed

Rikner, G

1985-01-01

Comparison of depth ionization distributions from a silicon semiconductor detector and depth dose curves from a plane parallel ionization chamber show that a semiconductor detector of p-type is well suited for relative electron dosimetry in the energy range of 6 to 20 MeV in Ep,0. Maximum deviations of the order of 1.5 per cent and of 1 mm were obtained down to a phantom depth of about 1 mm. The directional dependence of the detector was about 4 per cent.

Human Exposure to Electromagnetic Fields from Parallel Wireless Power Transfer Systems.

PubMed

Wen, Feng; Huang, Xueliang

2017-02-08

The scenario of multiple wireless power transfer (WPT) systems working closely, synchronously or asynchronously with phase difference often occurs in power supply for household appliances and electric vehicles in parking lots. Magnetic field leakage from the WPT systems is also varied due to unpredictable asynchronous working conditions. In this study, the magnetic field leakage from parallel WPT systems working with phase difference is predicted, and the induced electric field and specific absorption rate (SAR) in a human body standing in the vicinity are also evaluated. Computational results are compared with the restrictions prescribed in the regulations established to limit human exposure to time-varying electromagnetic fields (EMFs). The results show that the middle region between the two WPT coils is safer for the two WPT systems working in-phase, and the peripheral regions are safer around the WPT systems working anti-phase. Thin metallic plates larger than the WPT coils can shield the magnetic field leakage well, while smaller ones may worsen the situation. The orientation of the human body will influence the maximum magnitude of induced electric field and its distribution within the human body. The induced electric field centralizes in the trunk, groin, and genitals with only one exception: when the human body is standing right at the middle of the two WPT coils working in-phase, the induced electric field focuses on lower limbs. The SAR value in the lungs always seems to be greater than in other organs, while the value in the liver is minimal. Human exposure to EMFs meets the guidelines of the International Committee on Non-Ionizing Radiation Protection (ICNIRP), specifically reference levels with respect to magnetic field and basic restrictions on induced electric fields and SAR, as the charging power is lower than 3.1 kW and 55.5 kW, respectively. These results are positive with respect to the safe applications of parallel WPT systems working simultaneously.

Human Exposure to Electromagnetic Fields from Parallel Wireless Power Transfer Systems

PubMed Central

Wen, Feng; Huang, Xueliang

2017-01-01

The scenario of multiple wireless power transfer (WPT) systems working closely, synchronously or asynchronously with phase difference often occurs in power supply for household appliances and electric vehicles in parking lots. Magnetic field leakage from the WPT systems is also varied due to unpredictable asynchronous working conditions. In this study, the magnetic field leakage from parallel WPT systems working with phase difference is predicted, and the induced electric field and specific absorption rate (SAR) in a human body standing in the vicinity are also evaluated. Computational results are compared with the restrictions prescribed in the regulations established to limit human exposure to time-varying electromagnetic fields (EMFs). The results show that the middle region between the two WPT coils is safer for the two WPT systems working in-phase, and the peripheral regions are safer around the WPT systems working anti-phase. Thin metallic plates larger than the WPT coils can shield the magnetic field leakage well, while smaller ones may worsen the situation. The orientation of the human body will influence the maximum magnitude of induced electric field and its distribution within the human body. The induced electric field centralizes in the trunk, groin, and genitals with only one exception: when the human body is standing right at the middle of the two WPT coils working in-phase, the induced electric field focuses on lower limbs. The SAR value in the lungs always seems to be greater than in other organs, while the value in the liver is minimal. Human exposure to EMFs meets the guidelines of the International Committee on Non-Ionizing Radiation Protection (ICNIRP), specifically reference levels with respect to magnetic field and basic restrictions on induced electric fields and SAR, as the charging power is lower than 3.1 kW and 55.5 kW, respectively. These results are positive with respect to the safe applications of parallel WPT systems working simultaneously. PMID:28208709

Adapter plate assembly for adjustable mounting of objects

DOEpatents

Blackburn, R.S.

1986-05-02

An adapter plate and two locking discs are together affixed to an optic table with machine screws or bolts threaded into a fixed array of internally threaded holes provided in the table surface. The adapter plate preferably has two, and preferably parallel, elongated locating slots each freely receiving a portion of one of the locking discs for secure affixation of the adapter plate to the optic table. A plurality of threaded apertures provided in the adapter plate are available to attach optical mounts or other devices onto the adapter plate in an orientation not limited by the disposition of the array of threaded holes in the table surface. An axially aligned but radially offset hole through each locking disc receives a screw that tightens onto the table, such that prior to tightening of the screw the locking disc may rotate and translate within each locating slot of the adapter plate for maximum flexibility of the orientation thereof.

Adapter plate assembly for adjustable mounting of objects

DOEpatents

Blackburn, Robert S.

1987-01-01

An adapter plate and two locking discs are together affixed to an optic table with machine screws or bolts threaded into a fixed array of internally threaded holes provided in the table surface. The adapter plate preferably has two, and preferably parallel, elongated locating slots each freely receiving a portion of one of the locking discs for secure affixation of the adapter plate to the optic table. A plurality of threaded apertures provided in the adapter plate are available to attach optical mounts or other devices onto the adapter plate in an orientation not limited by the disposition of the array of threaded holes in the table surface. An axially aligned but radially offset hole through each locking disc receives a screw that tightens onto the table, such that prior to tightening of the screw the locking disc may rotate and translate within each locating slot of the adapter plate for maximum flexibility of the orientation thereof.

Salinity transfer in double diffusive convection bounded by two parallel plates

NASA Astrophysics Data System (ADS)

Yang, Yantao; van der Poel, Erwin P.; Ostilla-Monico, Rodolfo; Sun, Chao; Verzicco, Roberto; Grossmann, Siegfried; Lohse, Detlef

2014-11-01

The double diffusive convection (DDC) is the convection flow with the fluid density affected by two different components. In this study we numerically investigate DDC between two parallel plates with no-slip boundary conditions. The top plate has higher salinity and temperature than the lower one. Thus the flow is driven by the salinity difference and stabilised by the temperature difference. Our simulations are compared with the experiments by Hage and Tilgner (Phys. Fluids 22, 076603 (2010)) for several sets of parameters. Reasonable agreement is achieved for the salinity flux and its dependence on the salinity Rayleigh number. For all parameters considered, salt fingers emerge and extend through the entire domain height. The thermal Rayleigh number shows minor influence on the salinity flux although it does affect the Reynolds number. We apply the Grossmann-Lohse theory for Rayleigh-Bénard flow to the current problem without introducing any new coefficients. The theory successfully predicts the salinity flux with respect to the scaling for both the numerical and experimental results.

Parallel Fin ORU Thermal Interface for space applications. [Orbital Replaceable Unit

NASA Technical Reports Server (NTRS)

Stobb, C. A.; Limardo, Jose G.

1992-01-01

The Parallel Fin Thermal Interface has been developed as an Orbital Replaceable Unit (ORU) interface. The interface transfers heat from an ORU baseplate to a Heat Acquisition Plate (HAP) through pairs of fins sandwiched between insert plates that press against the fins with uniform pressure. The insert plates are spread apart for ORU baseplate separation and replacement. Two prototype interfaces with different fin dimensions were built (Model 140 and 380). Interfacing surface samples were found to have roughnesses of 56 to 89 nm. Conductance values of 267 to 420 W/sq m C were obtained for the 140 model in vacuum with interface pressures of 131 to 262 kPa (19 to 38 psi). Vacuum conductances ranging from 176 to 267 W/sq m F were obtained for the 380 model at interface pressures of 97 to 152 kPa (14 and 22 psi). Correlations from several sources were found to agree with test data within 20 percent using thermal math models of the interfaces.

Mixed Cassie-Baxter wetting states on a porous material stabilized by electrowetting

NASA Astrophysics Data System (ADS)

Lambert, Jérôme; Gauchet, Lucien; Crassous, Jérôme

2017-07-01

Electrowetting is used to force imbibition in model porous plates. These porous plates are sintered disordered bronze bead packings that are homogeneously coated with a constant-thickness layer of parylene. Cycles of increasing and decreasing voltage trigger the imbibition of a ionized water sessile drop by changing its contact angle with the porous material from non-wetting to wetting shapes. During a cycle, a drop experiences partial imbibition and a strong hysteresis of its contact angle with the porous plate. Since the imbibition process quickly stabilizes, we adopt an equilibrium description of the wetting properties of the drop on the porous plate. Our model, based on the Cassie-Baxter approach, shows that three different wetting states are experienced by the drop, one of which being made possible only by the modification of the contact angle inside the pores. Our model describes the experimental results very well.

Numerical simulation and analysis of electromagnetic-wave absorption of a plasma slab created by a direct-current discharge with gridded anode

NASA Astrophysics Data System (ADS)

Yuan, Chengxun; Tian, Ruihuan; Eliseev, S. I.; Bekasov, V. S.; Bogdanov, E. A.; Kudryavtsev, A. A.; Zhou, Zhongxiang

2018-03-01

In this paper, we present investigation of a direct-current discharge with a gridded anode from the point of view of using it as a means of creating plasma coating that could efficiently absorb incident electromagnetic (EM) waves. A single discharge cell consists of two parallel plates, one of which (anode) is gridded. Electrons emitted from the cathode surface are accelerated in the short interelectrode gap and are injected into the post-anode space, where they lose acquired energy on ionization and create plasma. Numerical simulations were used to investigate the discharge structure and obtain spatial distributions of plasma density in the post-anode space. The numerical model of the discharge was based on a simple hybrid approach which takes into account non-local ionization by fast electrons streaming from the cathode sheath. Specially formulated transparency boundary conditions allowed performing simulations in 1D. Simulations were carried out in air at pressures of 10 Torr and higher. Analysis of the discharge structure and discharge formation is presented. It is shown that using cathode materials with lower secondary emission coefficients can allow increasing the thickness of plasma slabs for the same discharge current, which can potentially enhance EM wave absorption. Spatial distributions of electron density obtained during simulations were used to calculate attenuation of an incident EM wave propagating perpendicularly to the plasma slab boundary. It is shown that plasma created by means of a DC discharge with a gridded anode can efficiently absorb EM waves in the low frequency range (6-40 GHz). Increasing gas pressure results in a broader range of wave frequencies (up to 500 GHz) where a considerable attenuation is observed.

Ongoing revolution in bacteriology: routine identification of bacteria by matrix-assisted laser desorption ionization time-of-flight mass spectrometry.

PubMed

Seng, Piseth; Drancourt, Michel; Gouriet, Frédérique; La Scola, Bernard; Fournier, Pierre-Edouard; Rolain, Jean Marc; Raoult, Didier

2009-08-15

Matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry accurately identifies both selected bacteria and bacteria in select clinical situations. It has not been evaluated for routine use in the clinic. We prospectively analyzed routine MALDI-TOF mass spectrometry identification in parallel with conventional phenotypic identification of bacteria regardless of phylum or source of isolation. Discrepancies were resolved by 16S ribosomal RNA and rpoB gene sequence-based molecular identification. Colonies (4 spots per isolate directly deposited on the MALDI-TOF plate) were analyzed using an Autoflex II Bruker Daltonik mass spectrometer. Peptidic spectra were compared with the Bruker BioTyper database, version 2.0, and the identification score was noted. Delays and costs of identification were measured. Of 1660 bacterial isolates analyzed, 95.4% were correctly identified by MALDI-TOF mass spectrometry; 84.1% were identified at the species level, and 11.3% were identified at the genus level. In most cases, absence of identification (2.8% of isolates) and erroneous identification (1.7% of isolates) were due to improper database entries. Accurate MALDI-TOF mass spectrometry identification was significantly correlated with having 10 reference spectra in the database (P=.01). The mean time required for MALDI-TOF mass spectrometry identification of 1 isolate was 6 minutes for an estimated 22%-32% cost of current methods of identification. MALDI-TOF mass spectrometry is a cost-effective, accurate method for routine identification of bacterial isolates in <1 h using a database comprising > or =10 reference spectra per bacterial species and a 1.9 identification score (Brucker system). It may replace Gram staining and biochemical identification in the near future.

Performance evaluation of parallel electric field tunnel field-effect transistor by a distributed-element circuit model

NASA Astrophysics Data System (ADS)

Morita, Yukinori; Mori, Takahiro; Migita, Shinji; Mizubayashi, Wataru; Tanabe, Akihito; Fukuda, Koichi; Matsukawa, Takashi; Endo, Kazuhiko; O'uchi, Shin-ichi; Liu, Yongxun; Masahara, Meishoku; Ota, Hiroyuki

2014-12-01

The performance of parallel electric field tunnel field-effect transistors (TFETs), in which band-to-band tunneling (BTBT) was initiated in-line to the gate electric field was evaluated. The TFET was fabricated by inserting an epitaxially-grown parallel-plate tunnel capacitor between heavily doped source wells and gate insulators. Analysis using a distributed-element circuit model indicated there should be a limit of the drain current caused by the self-voltage-drop effect in the ultrathin channel layer.

Prediction and measurement of heat transfer rates for the shock-induced unsteady laminar boundary layer on a flat plate

NASA Technical Reports Server (NTRS)

Cook, W. J.

1972-01-01

The unsteady laminar boundary layer induced by the flow-initiating shock wave passing over a flat plate mounted in a shock tube was theoretically and experimentally studied in terms of heat transfer rates to the plate for shock speeds ranging from 1.695 to 7.34 km/sec. The theory presented by Cook and Chapman for the shock-induced unsteady boundary layer on a plate is reviewed with emphasis on unsteady heat transfer. A method of measuring time-dependent heat-transfer rates using thin-film heat-flux gages and an associated data reduction technique are outlined in detail. Particular consideration is given to heat-flux measurement in short-duration ionized shocktube flows. Experimental unsteady plate heat transfer rates obtained in both air and nitrogen using thin-film heat-flux gages generally agree well with theoretical predictions. The experimental results indicate that the theory continues to predict the unsteady boundary layer behavior after the shock wave leaves the trailing edge of the plate even though the theory is strictly applicable only for the time interval in which the shock remains on the plate.

40 CFR 63.11507 - What are my standards and management practices?

Code of Federal Regulations, 2011 CFR

2011-07-01

... distilled/de-ionized water, water filtration, pre-cleaning of parts to be plated, and thorough rinsing of... emissions from the thermal spraying process and transports the emissions to a water curtain, fabric filter... and transports the emissions to a water curtain, fabric filter, cartridge, or HEPA filter, according...

Ionizing radiation-induced mutagenesis: radiation studies in Neurospora predictive for results in mammalian cells

NASA Technical Reports Server (NTRS)

Evans, H. H.; DeMarini, D. M.

1999-01-01

Ionizing radiation was the first mutagen discovered and was used to develop the first mutagenicity assay. In the ensuing 70+ years, ionizing radiation became a fundamental tool in understanding mutagenesis and is still a subject of intensive research. Frederick de Serres et al. developed and used the Neurospora crassa ad-3 system initially to explore the mutagenic effects of ionizing radiation. Using this system, de Serres et al. demonstrated the dependence of the frequency and spectra of mutations induced by ionizing radiation on the dose, dose rate, radiation quality, repair capabilities of the cells, and the target gene employed. This work in Neurospora predicted the subsequent observations of the mutagenic effects of ionizing radiation in mammalian cells. Modeled originally on the mouse specific-locus system developed by William L. Russell, the N. crassa ad-3 system developed by de Serres has itself served as a model for interpreting the results in subsequent systems in mammalian cells. This review describes the primary findings on the nature of ionizing radiation-induced mutagenesis in the N. crassa ad-3 system and the parallel observations made years later in mammalian cells.

Electron-impact-ionization dynamics of S F6

NASA Astrophysics Data System (ADS)

Bull, James N.; Lee, Jason W. L.; Vallance, Claire

2017-10-01

A detailed understanding of the dissociative electron ionization dynamics of S F6 is important in the modeling and tuning of dry-etching plasmas used in the semiconductor manufacture industry. This paper reports a crossed-beam electron ionization velocity-map imaging study on the dissociative ionization of cold S F6 molecules, providing complete, unbiased kinetic energy distributions for all significant product ions. Analysis of these distributions suggests that fragmentation following single ionization proceeds via formation of S F5 + or S F3 + ions that then dissociate in a statistical manner through loss of F atoms or F2, until most internal energy has been liberated. Similarly, formation of stable dications is consistent with initial formation of S F4 2 + ions, which then dissociate on a longer time scale. These data allow a comparison between electron ionization and photoionization dynamics, revealing similar dynamical behavior. In parallel with the ion kinetic energy distributions, the velocity-map imaging approach provides a set of partial ionization cross sections for all detected ionic fragments over an electron energy range of 50-100 eV, providing partial cross sections for S2 +, and enables the cross sections for S F4 2 + from S F+ to be resolved.

Comparison of the lowest-order transverse-electric (TE1) and transverse-magnetic (TEM) modes of the parallel-plate waveguide for terahertz pulse applications.

PubMed

Mendis, Rajind; Mittleman, Daniel M

2009-08-17

We present a comprehensive experimental study comparing the propagation characteristics of the virtually unknown TE(1) mode to the well-known TEM mode of the parallel-plate waveguide (PPWG), for THz pulse applications. We demonstrate that it is possible to overcome the undesirable effects caused by the TE(1) mode's inherent low-frequency cutoff, making it a viable THz wave-guiding option, and that for certain applications, the TE(1) mode may even be more desirable than the TEM mode. This study presents a whole new dimension to the THz technological capabilities offered by the PPWG, via the possible use of the TE(1) mode. (c) 2009 Optical Society of America

Minimizing Concentration Effects in Water-Based, Laminar-Flow Condensation Particle Counters

PubMed Central

Lewis, Gregory S.; Hering, Susanne V.

2013-01-01

Concentration effects in water condensation systems, such as used in the water-based condensation particle counter, are explored through numeric modeling and direct measurements. Modeling shows that the condensation heat release and vapor depletion associated with particle activation and growth lowers the peak supersaturation. At higher number concentrations, the diameter of the droplets formed is smaller, and the threshold particle size for activation is higher. This occurs in both cylindrical and parallel plate geometries. For water-based systems we find that condensational heat release is more important than is vapor depletion. We also find that concentration effects can be minimized through use of smaller tube diameters, or more closely spaced parallel plates. Experimental measurements of droplet diameter confirm modeling results. PMID:24436507

Unsteady MHD blood flow through porous medium in a parallel plate channel

NASA Astrophysics Data System (ADS)

Latha, R.; Rushi Kumar, B.

2017-11-01

In this study, we have analyzed heat and mass transfer effects on unsteady blood flow through parallel plate channel in a saturated porous medium in the presence of a transverse magnetic field with thermal radiation. The governing higher order nonlinear PDE’S are converted to dimensionless equations using dimensionless variables. The dimensionless equations are then solved analytically using boundary conditions by choosing the axial flow transport and the fields of concentration and temperature apart from the normal velocity as a function of y and t. The effects of different pertinent parameters appeared in this model viz thermal radiation, Prandtl number, Heat source parameter, Hartmann number, Permeability parameter, Decay parameter on axial flow transport and the normal velocity are analyzed in detail.

A proposed experimental search for chameleons using asymmetric parallel plates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burrage, Clare; Copeland, Edmund J.; Stevenson, James A., E-mail: Clare.Burrage@nottingham.ac.uk, E-mail: ed.copeland@nottingham.ac.uk, E-mail: james.stevenson@nottingham.ac.uk

2016-08-01

Light scalar fields coupled to matter are a common consequence of theories of dark energy and attempts to solve the cosmological constant problem. The chameleon screening mechanism is commonly invoked in order to suppress the fifth forces mediated by these scalars, sufficiently to avoid current experimental constraints, without fine tuning. The force is suppressed dynamically by allowing the mass of the scalar to vary with the local density. Recently it has been shown that near future cold atoms experiments using atom-interferometry have the ability to access a large proportion of the chameleon parameter space. In this work we demonstrate howmore » experiments utilising asymmetric parallel plates can push deeper into the remaining parameter space available to the chameleon.« less

A Model for Displacements Between Parallel Plates That Shows Change of Type from Hyperbolic to Elliptic

NASA Astrophysics Data System (ADS)

Shariati, Maryam; Yortsos, Yannis; Talon, Laurent; Martin, Jerome; Rakotomalala, Nicole; Salin, Dominique

2003-11-01

We consider miscible displacement between parallel plates, where the viscosity is a function of the concentration. By selecting a piece-wise representation, the problem can be considered as ``three-phase'' flow. Assuming a lubrication-type approximation, the mathematical description is in terms of two quasi-linear hyperbolic equations. When the mobility of the middle phase is smaller than its neighbors, the system is genuinely hyperbolic and can be solved analytically. However, when it is larger, an elliptic region develops. This change-of-type behavior is for the first time proved here based on sound physical principles. Numerical solutions with a small diffusion are presented. Good agreement is obtained outside the elliptic region, but not inside, where the numerical results show unstable behavior. We conjecture that for the solution of the real problem in the mixed-type case, the full higher-dimensionality problem must be considered inside the elliptic region, in which the lubrication (parallel-flow) approximation is no longer appropriate. This is discussed in a companion presentation.

Chemical vapor deposition of aminopropyl silanes in microfluidic channels for highly efficient microchip capillary electrophoresis-electrospray ionization-mass spectrometry.

PubMed

Batz, Nicholas G; Mellors, J Scott; Alarie, Jean Pierre; Ramsey, J Michael

2014-04-01

We describe a chemical vapor deposition (CVD) method for the surface modification of glass microfluidic devices designed to perform electrophoretic separations of cationic species. The microfluidic channel surfaces were modified using aminopropyl silane reagents. Coating homogeneity was inferred by precise measurement of the separation efficiency and electroosmotic mobility for multiple microfluidic devices. Devices coated with (3-aminopropyl)di-isopropylethoxysilane (APDIPES) yielded near diffusion-limited separations and exhibited little change in electroosmotic mobility between pH 2.8 and pH 7.5. We further evaluated the temporal stability of both APDIPES and (3-aminopropyl)triethoxysilane (APTES) coatings when stored for a total of 1 week under vacuum at 4 °C or filled with pH 2.8 background electrolyte at room temperature. Measurements of electroosmotic flow (EOF) and separation efficiency during this time confirmed that both coatings were stable under both conditions. Microfluidic devices with a 23 cm long, serpentine electrophoretic separation channel and integrated nanoelectrospray ionization emitter were CVD coated with APDIPES and used for capillary electrophoresis (CE)-electrospray ionization (ESI)-mass spectrometry (MS) of peptides and proteins. Peptide separations were fast and highly efficient, yielding theoretical plate counts over 600,000 and a peak capacity of 64 in less than 90 s. Intact protein separations using these devices yielded Gaussian peak profiles with separation efficiencies between 100,000 and 400,000 theoretical plates.

Direct targeting of human plasma for matrix-assisted laser desorption/ionization and analysis of plasma proteins by time of flight-mass spectrometry.

PubMed

Jin, Ya; Manabe, Takashi

2005-07-01

A method to analyze human plasma proteins without fractionation, directly applying a plasma-matrix mixture on the target plate of a matrix-assisted laser desorption/ionization-time of flight-mass spectrometer (MALDI-TOF-MS), has been described. Peaks of ionized plasma proteins could not be detected applying a mixture of an undiluted plasma sample and a matrix solution, but they appeared when the plasma was diluted before mixing with the matrix. Tenfold diluted plasma provided well-resolved protein peaks in the m/z range from 4000 to 30,000. The addition of a simple post-crystallization washing procedure performed on the target plate further improved the quality of mass spectra. We numbered 58 peaks in the range of 4-160 kDa and 32 out of which were assigned to the plasma protein species which have been reported. Especially high sensitivity and resolution were obtained in the region < 30 kDa, where multiple isoforms of apolipoprotein A-I, apolipoprotein A-II, apolipoprotein C-I, apolipoprotein C-II, apolipoprotein C-III, and transthyretin could be assigned. Various post-translational modifications are involved in the isoforms, e.g., proteolytic cleavage, glycosylation and chemical modifications. This method will become complementary with the present electrophoretic techniques, especially for the analysis of low-molecular-mass proteins.

Seismic anisotropy beneath South China Sea: using SKS splitting to constrain mantle flow

NASA Astrophysics Data System (ADS)

Xue, M.; Le, K.; Yang, T.

2011-12-01

The evolution of South China Sea is under debate and several hypotheses have been proposed: (1) The collision of India plate and Eurasia plate; (2) the backward movement of the Pacific subduction plate; (3) mantle upwelling; and (4) combinations of above hypotheses. All these causal mechanisms emphasize the contributions of deep structures to the evolution of South China Sea. In this study we use earthquake data recorded by seismic stations surrounding South China Sea to constrain mantle flow beneath. To fill the vacancy of seismic data in Viet Nam, we deployed 4 seismic stations (VT01-VT04) in a roughly north - south orientation in Viet Nam in Nov. 2009. We combine the VT dataset with the AD and MY datasets from IRIS and select 81 events for SKS splitting analysis. Measurements were made at 11 stations using Wolfe and Silver (1998)'s multi-event stacking procedure. Our observed splitting directions in Vietnam are generally consistent with those of Bai et. al. (2009) . In northern Vietnam, the splitting times are around 1 sec and the fast directions are NWW-SEE, parallel to the absolute plate motion as well as the motion of the Earth surface, implying the crust and the mantle are coupled in this region and is moving as a result of the collision of India and China. While in southern Vietnam and Malaya, the fast directions are NE-SW, almost perpendicular to the absolute plate motion as well as the surface motion of Eurasia plate. However, the observed NE-SW is parallel to the subduction direction of the Australian plate, which might be caused by the mantle flow along NE-SW induced by the subduction.

Large-area field-ionization detector for the study of Rydberg atoms.

PubMed

Jones, A C L; Piñeiro, A M; Roeder, E E; Rutbeck-Goldman, H J; Tom, H W K; Mills, A P

2016-11-01

We describe here the development and characterization of a micro-channel plate (MCP) based detector designed for the efficient collection and detection of Rydberg positronium (Ps) atoms for use in a time-of-flight apparatus. The designed detector collects Rydberg atoms over a large area (∼4 times greater than the active area of the MCP), ionizing incident atoms and then collecting and focusing the freed positrons onto the MCP. Here we discuss the function, design, and optimization of the device. The detector has an efficiency for Rydberg Ps that is two times larger than that of the γ-ray scintillation detector based scheme it has been designed to replace, with half the background signal. In principle, detectors of the type described here could be readily employed for the detection of any Rydberg atom species, provided a sufficient field can be applied to achieve an ionization rate of ≥10 8 /s. In such cases, the best time resolution would be achieved by collecting ionized electrons rather than the positive ions.

Monte Carlo calculation of energy deposition in ionization chambers for tritium measurements

NASA Astrophysics Data System (ADS)

Zhilin, Chen; Shuming, Peng; Dan, Meng; Yuehong, He; Heyi, Wang

2014-10-01

Energy deposition in ionization chambers for tritium measurements has been theoretically studied using Monte Carlo code MCNP 5. The influence of many factors, including carrier gas, chamber size, wall materials and gas pressure, has been evaluated in the simulations. It is found that β rays emitted by tritium deposit much more energy into chambers flowing through with argon than with deuterium in them, as much as 2.7 times higher at pressure 100 Pa. As chamber size gets smaller, energy deposition decreases sharply. For an ionization chamber of 1 mL, β rays deposit less than 1% of their energy at pressure 100 Pa and only 84% even if gas pressure is as high as 100 kPa. It also indicates that gold plated ionization chamber results in the highest deposition ratio while aluminum one leads to the lowest. In addition, simulations were validated by comparison with experimental data. Results show that simulations agree well with experimental data.

Method for controlling protein crystallization

NASA Technical Reports Server (NTRS)

Noever, David A. (Inventor)

1993-01-01

A method and apparatus for controlling the crystallization of protein by solvent evaporation including placing a drop of protein solution between and in contact with a pair of parallel plates and driving one of the plates toward and away from the other plate in a controlled manner to adjust the spacing between the plates is presented. The drop of solution forms a liquid cylinder having a height dependent upon the plate spacing thereby effecting the surface area available for solvent evaporation. When the spacing is close, evaporation is slow. Evaporation is increased by increasing the spacing between the plates until the breaking point of the liquid cylinder. One plate is mounted upon a fixed post while the other plate is carried by a receptacle movable relative to the post and driven by a belt driven screw drive. The temperature and humidity of the drop of protein solution are controlled by sealing the drop within the receptacle and mounting a heater and dessicant within the receptacle.

Fabrication of gas impervious edge seal for a bipolar gas distribution assembly for use in a fuel cell

DOEpatents

Kaufman, Arthur; Werth, John

1986-01-01

A bipolar gas reactant distribution assembly for use in a fuel cell is disclosed, the assembly having a solid edge seal to prevent leakage of gaseous reactants wherein a pair of porous plates are provided with peripheral slits generally parallel to, and spaced apart from two edges of the plate, the slit being filled with a solid, fusible, gas impervious edge sealing compound. The plates are assembled with opposite faces adjacent one another with a layer of a fusible sealant material therebetween the slits in the individual plates being approximately perpendicular to one another. The plates are bonded to each other by the simultaneous application of heat and pressure to cause a redistribution of the sealant into the pores of the adjacent plate surfaces and to cause the edge sealing compound to flow and impregnate the region of the plates adjacent the slits and comingle with the sealant layer material to form a continuous layer of sealant along the edges of the assembled plates.

Pulsed ultrasonic stir welding system

NASA Technical Reports Server (NTRS)

Ding, R. Jeffrey (Inventor)

2013-01-01

An ultrasonic stir welding system includes a welding head assembly having a plate and a rod passing through the plate. The rod is rotatable about a longitudinal axis thereof. During a welding operation, ultrasonic pulses are applied to the rod as it rotates about its longitudinal axis. The ultrasonic pulses are applied in such a way that they propagate parallel to the longitudinal axis of the rod.

The Anisotropic Structure of South China Sea: Using OBS Data to Constrain Mantle Flow

NASA Astrophysics Data System (ADS)

Li, L.; Xue, M.; Yang, T.; Liu, C.; Hua, Q.; Xia, S.; Huang, H.; Le, B. M.; Huo, D.; Pan, M.

2015-12-01

The dynamic mechanism of the formation of South China Sea (SCS) has been debated for decades. The anisotropic structure can provide useful insight into the complex evolution of SCS by indicating its mantle flow direction and strength. In this study, we employ shear wave splitting methods on two half-year seismic data collected from 10 and 6 passive source Ocean Bottom Seismometers (OBS) respectively. These OBSs were deployed along both sides of the extinct ridge in the central basin of SCS by Tongji University in 2012 and 2013 respectively, which were then successfully recovered in 2013 and 2015 respectively. Through processing and inspecting the global and regional earthquakes (with local events being processing) of the 2012 dataset, measurements are made for 2 global events and 24 regional events at 5 OBSs using the tangential energy minimization, the smallest eigenvalue minimization, as well as the correlation methods. We also implement cluster analysis on the splitting results obtained for different time windows as well as filtered at different frequency bands. For teleseismic core phases like SKS and PKS, we find the fast polarization direction beneath the central basin is approximately NE-SW, nearly parallel to the extinct ridge in the central basin of SCS. Whereas for regional events, the splitting analysis on S, PS and ScS phases shows much more complicated fast directions as the ray path varies for different phases. The fast directions observed can be divided into three groups: (1) for the events from the Eurasia plate, a gradual rotation of the fast polarization direction from NNE-SSW to NEE-SWW along the path from the inner Eurasia plate to the central SCS is observed, implying the mantle flow is controlled by the India-Eurasia collision; (2) for the events located at the junction of Pacific plate and Philippine plate, the dominant fast direction is NW-SE, almost perpendicular to Ryukyu Trench as well as sub-parallel to the absolute direction of Philippine plate; (3) for the events occurred in the SE direction near the Philippine Fault zone, the observed NE-SW fast direction is sub-parallel to the subduction direction of the Philippine plate.

Hybrid Parallelization of Adaptive MHD-Kinetic Module in Multi-Scale Fluid-Kinetic Simulation Suite

DOE PAGES

Borovikov, Sergey; Heerikhuisen, Jacob; Pogorelov, Nikolai

2013-04-01

The Multi-Scale Fluid-Kinetic Simulation Suite has a computational tool set for solving partially ionized flows. In this paper we focus on recent developments of the kinetic module which solves the Boltzmann equation using the Monte-Carlo method. The module has been recently redesigned to utilize intra-node hybrid parallelization. We describe in detail the redesign process, implementation issues, and modifications made to the code. Finally, we conduct a performance analysis.

Dynamical Instability Produces Transform Faults at Mid-Ocean Ridges

NASA Astrophysics Data System (ADS)

Gerya, Taras

2010-08-01

Transform faults at mid-ocean ridges—one of the most striking, yet enigmatic features of terrestrial plate tectonics—are considered to be the inherited product of preexisting fault structures. Ridge offsets along these faults therefore should remain constant with time. Here, numerical models suggest that transform faults are actively developing and result from dynamical instability of constructive plate boundaries, irrespective of previous structure. Boundary instability from asymmetric plate growth can spontaneously start in alternate directions along successive ridge sections; the resultant curved ridges become transform faults within a few million years. Fracture-related rheological weakening stabilizes ridge-parallel detachment faults. Offsets along the transform faults change continuously with time by asymmetric plate growth and discontinuously by ridge jumps.

CALUTRON

DOEpatents

Schmidt, F.H.

1958-08-12

An improved ion source is described for accurately presetting the size amd location of the gas and ion efflux opening. for determining the contour of the electrical field in the vicinity of the arc, and for generally improving the operation of the calutron source. The above features are accomplished by the use of a pair of electrically conductive coplanar plates mounted on opposite sides of the ion exit passage of the source ionization chamber and electrically connected to the source block. The plates are mounted on thc block for individual movement tramsversely of the exit slit and can be secured in place by clannping means.

Status of Pulsed Inductive Thruster Research

NASA Technical Reports Server (NTRS)

Hrbud, Ivana; LaPointe, Michael; Vondra, Robert; Lovberg, Ralph; Dailey, C. Lee; Schafer, Charles (Technical Monitor)

2002-01-01

The TRW Pulsed Inductive Thruster (PIT) is an electromagnetic propulsion system that can provide high thrust efficiency over a wide range of specific impulse values. In its basic form, the PIT consists of a flat spiral coil covered by a thin dielectric plate. A pulsed gas injection nozzle distributes a thin layer of gas propellant across the plate surface at the same time that a pulsed high current discharge is sent through the coil. The rising current creates a time varying magnetic field, which in turn induces a strong azimuthal electric field above the coil. The electric field ionizes the gas propellant and generates an azimuthal current flow in the resulting plasma. The current in the plasma and the current in the coil flow in opposite directions, providing a mutual repulsion that rapidly blows the ionized propellant away from the plate to provide thrust. The thrust and specific impulse can be tailored by adjusting the discharge power, pulse repetition rate, and propellant mass flow, and there is minimal if any erosion due to the electrodeless nature of the discharge. Prior single-shot experiment,; performed with a Diameter diameter version of the PIT at TRW demonstrated specific impulse values between 2,000 seconds and 8,000 seconds, with thruster efficiencies of about 52% for ammonia. This paper outlines current and planned activities to transition the single shot device into a multiple repetition rate thruster capable of supporting NASA strategic enterprise missions.

Nanoactuators Based on Electrostatic Forces on Dielectrics

NASA Technical Reports Server (NTRS)

Wang, Yu

2005-01-01

Nanoactuators of a proposed type would exploit the forces exerted by electric fields on dielectric materials. As used here, "nanoactuators" includes motors, manipulators, and other active mechanisms that have dimensions of the order of nanometers and/or are designed to manipulate objects that have dimensions of the order of nanometers. The underlying physical principle can be described most simply in terms of the example of a square parallel-plate capacitor in which a square dielectric plate is inserted part way into the gap between the electrode plates (see Figure Typically, the force is small from our macroscopic human perspective. The above equation shows that the force depends on the ratio between the capacitor dimensions but does not depend on the size. In other words, the force remains the same if the capacitor and the dielectric slab are shrunk to nanometer dimensions. At the same time, the masses of all components are proportional to third power of their linear dimensions. Therefore the force-to-mass ratio (and, consequently, the acceleration that can be imparted to the dielectric slab) is much larger at the nanoscale than at the macroscopic scale. The proposed actuators would exploit this effect. The upper part of Figure 2 depicts a simple linear actuator based on a parallel- plate capacitor similar to Figure 1. In this case, the upper electrode plate would be split into two parts (A and B) and the dielectric slab would be slightly longer than plate A or B. The actuator would be operated in a cycle. During the first half cycle, plate B would be grounded to the lower plate and plate A would be charged to a potential, V, with respect to the lower plate, causing the dielectric slab to be pulled under plate A. During the second half cycle, plate A would be grounded and plate B would be charged to potential V, causing the dielectric slab to be pulled under plate B. The back-and-forth motion caused by alternation of the voltages on plates A and B could be used to drive a nanopump, for example. A rotary motor, shown in the middle part of Figure 2, could include a dielectric rotor sandwiched between a top and a bottom plate containing multiple electrodes arranged symmetrically in a circle. Voltages would be applied sequentially to electrode pairs 1 and 1a, then 2 and 2a, then 3 and 3a in order to attract the dielectric rotor to sequential positions between the electrode pairs.

Numerical and analytical studies of critical radius in spherical and cylindrical geometries for corona discharge in air and CO2-rich environments

NASA Astrophysics Data System (ADS)

Engle, J. A.; Riousset, J. A.

2016-12-01

In order to determine the most effective geometry of a lightning rod, one must first understand the physical difference between their current designs. Benjamin Franklin's original theory of sharp tipped rods suggests an increase of local electric field, while Moore et al.'s (2000) studies of rounded tips evince an increased probability of strike (Moore et al., 2000; Gibson et al., 2009).In this analysis, the plasma discharge is produced between two electrodes with a high potential difference, resulting in ionization of the neutral gas particle. This process, when done at low current and low temperature can create a corona discharges, which can be observed as a luminescent emission. The Cartesian geometry known as Paschen, or Townsend, theory is particularly well suited to model experimental laboratory scenario, however, it is limited in its applicability to lightning rods. Franklin's sharp tip and Moore et al.'s (2000) rounded tip fundamentally differ in the radius of curvature of the upper end of the rod. As a first approximation, the rod can be modelled as an equipotential conducting sphere above the ground. Hence, we expand the classic Cartesian geometry into spherical and cylindrical geometries. In this work we explore the effects of shifting from the classical parallel plate analysis to spherical and cylindrical geometries more adapted for studies of lightning rods or power lines. Utilizing Townsend's equation for corona discharge, we estimate a critical radius and minimum breakdown voltage that allows ionization of the air around an electrode. Additionally, we explore the influence of the gas in which the discharge develops. We use BOLSIG+, a numerical solver for the Boltzmann equation, to calculate Townsend coefficients for CO2-rich atmospheric conditions. This allows us to expand the scope of this study to other planetary bodies such as Mars (Hagelaar, 2005). We solve the problem both numerically and analytically to present simplified formulas per each geometry and gas mixture. The development of a numerical framework will ultimately let us test the influence of additional parameters such as background ionization, initiation criterion, and charge conservation on the values of the critical radius and minimum breakdown voltage.

HPCC Methodologies for Structural Design and Analysis on Parallel and Distributed Computing Platforms

NASA Technical Reports Server (NTRS)

Farhat, Charbel

1998-01-01

In this grant, we have proposed a three-year research effort focused on developing High Performance Computation and Communication (HPCC) methodologies for structural analysis on parallel processors and clusters of workstations, with emphasis on reducing the structural design cycle time. Besides consolidating and further improving the FETI solver technology to address plate and shell structures, we have proposed to tackle the following design related issues: (a) parallel coupling and assembly of independently designed and analyzed three-dimensional substructures with non-matching interfaces, (b) fast and smart parallel re-analysis of a given structure after it has undergone design modifications, (c) parallel evaluation of sensitivity operators (derivatives) for design optimization, and (d) fast parallel analysis of mildly nonlinear structures. While our proposal was accepted, support was provided only for one year.

Preliminary Diffusive Clearance of Silicon Nanopore Membranes in a Parallel Plate Configuration for Renal Replacement Therapy

PubMed Central

Kim, Steven; Heller, James; Iqbal, Zohora; Kant, Rishi; Kim, Eun Jung; Durack, Jeremy; Saeed, Maythem; Do, Loi; Hetts, Steven; Wilson, Mark; Brakeman, Paul; Fissell, William H.; Roy, Shuvo

2015-01-01

Silicon nanopore membranes (SNM) with compact geometry and uniform pore size distribution have demonstrated a remarkable capacity for hemofiltration. These advantages could potentially be used for hemodialysis. Here we present an initial evaluation of the SNM’s mechanical robustness, diffusive clearance, and hemocompatibility in a parallel plate configuration. Mechanical robustness of the SNM was demonstrated by exposing membranes to high flows (200ml/min) and pressures (1,448mmHg). Diffusive clearance was performed in an albumin solution and whole blood with blood and dialysate flow rates of 25ml/min. Hemocompatibility was evaluated using scanning electron microscopy and immunohistochemistry after 4-hours in an extra-corporeal porcine model. The pressure drop across the flow cell was 4.6mmHg at 200ml/min. Mechanical testing showed that SNM could withstand up to 775.7mmHg without fracture. Urea clearance did not show an appreciable decline in blood versus albumin solution. Extra-corporeal studies showed blood was successfully driven via the arterial-venous pressure differential without thrombus formation. Bare silicon showed increased cell adhesion with a 4.1 fold increase and 1.8 fold increase over polyethylene-glycol (PEG)-coated surfaces for tissue plasminogen factor (t-PA) and platelet adhesion (CD-41), respectively. These initial results warrant further design and development of a fully scaled SNM-based parallel plate dialyzer for renal replacement therapy. PMID:26692401

Elements of radiative interactions in gaseous systems

NASA Technical Reports Server (NTRS)

Tiwari, Surendra N.

1991-01-01

Basic formulations, analyses, and numerical procedures are presented to study radiative interactions in gray as well as nongray gases under different physical and flow conditions. After preliminary fluid-dynamical considerations, essential governing equations for radiative transport are presented that are applicable under local and nonlocal thermodynamic equilibrium conditions. Auxiliary relations for relaxation times and spectral absorption model are also provided. For specific applications, several simple gaseous systems are analyzed. The first system considered consists of a gas bounded by two parallel plates having the same temperature. For this system, both vibrational nonequilibrium effects and radiation conduction interactions are studied. The second system consists of fully developed laminar flow and heat transfer in a parallel plate duct under the boundary condition of a uniform surface heat flux. For this system, effects of gray surface emittance are studied. With the single exception of a circular geometry, the third system is identical to the second system. Here, the influence of nongray walls is also studied, and a correlation between the parallel plates and circular tube results is presented. The particular gases selected are CO, CO2, H2O, CH4, N2O, NH3, OH, and NO. The temperature and pressure range considered are 300 to 2000 K, and 0.1 to 100 atmosphere, respectively. Illustrative results obtained for different cases are discussed and some specific conclusions are provided.

Plate convergence, transcurrent faults and internal deformation adjacent to Southeast Asia and the western Pacific

NASA Technical Reports Server (NTRS)

Fitch, T. J.

1971-01-01

A model for oblique convergence between plates of lithosphere is proposed in which at least a fraction of slip parallel to the plate margin results in transcurrent movements on a nearly vertical fault which is located on the continental side of a zone of plate consumption. In an extreme case of complete decoupling only the component of slip normal to the plate margin can be inferred from underthrusting. Recent movements in the western Sunda region provide the most convincing evidence for decoupling of slip, which in this region is thought to be oblique to the plate margin. A speculative model for convergence along the margins of the Philippine Sea is constructed from an inferred direction of oblique slip in the Philippine region. This model requires that the triple point formed by the junction of the Japanese and Izu-Bonin trenches and the Nankai trough migrate along the Sagami trough.

Fuel cell plates with improved arrangement of process channels for enhanced pressure drop across the plates

DOEpatents

Spurrier, Francis R.; Pierce, Bill L.; Wright, Maynard K.

1986-01-01

A plate for a fuel cell has an arrangement of ribs defining an improved configuration of process gas channels and slots on a surface of the plate which provide a modified serpentine gas flow pattern across the plate surface. The channels are generally linear and arranged parallel to one another while the spaced slots allow cross channel flow of process gas in a staggered fashion which creates a plurality of generally mini-serpentine flow paths extending transverse to the longitudinal gas flow along the channels. Adjacent pairs of the channels are interconnected to one another in flow communication. Also, a bipolar plate has the aforementioned process gas channel configuration on one surface and another configuration on the opposite surface. In the other configuration, there are not slots and the gas flow channels have a generally serpentine configuration.

Pyroelectricity Assisted Infrared-Laser Desorption Ionization (PAI-LDI) for Atmospheric Pressure Mass Spectrometry

NASA Astrophysics Data System (ADS)

Li, Yanyan; Ma, Xiaoxiao; Wei, Zhenwei; Gong, Xiaoyun; Yang, Chengdui; Zhang, Sichun; Zhang, Xinrong

2015-08-01

A new atmospheric pressure ionization method termed pyroelectricity-assisted infrared laser desorption ionization (PAI-LDI) was developed in this study. The pyroelectric material served as both sample target plate and enhancing ionization substrate, and an IR laser with wavelength of 1064 nm was employed to realize direct desorption and ionization of the analytes. The mass spectra of various compounds obtained on pyroelectric material were compared with those of other substrates. For the five standard substances tested in this work, LiNbO3 substrate produced the highest ion yield and the signal intensity was about 10 times higher than that when copper was used as substrate. For 1-adamantylamine, as low as 20 pg (132.2 fmol) was successfully detected. The active ingredient in (Compound Paracetamol and 1-Adamantylamine Hydrochloride Capsules), 1-adamantylamine, can be sensitively detected at an amount as low as 150 pg, when the medicine stock solution was diluted with urine. Monosaccharide and oligosaccharides in Allium Cepa L. juice was also successfully identified with PAI-LDI. The method did not require matrix-assisted external high voltage or other extra facility-assisted set-ups for desorption/ionization. This study suggested exciting application prospect of pyroelectric materials in matrix- and electricity-free atmospheric pressure mass spectrometry research.

Ionization and excitation in cool giant stars. I - Hydrogen and helium

NASA Technical Reports Server (NTRS)

Luttermoser, Donald G.; Johnson, Hollis R.

1992-01-01

The influence that non-LTE radiative transfer has on the electron density, ionization equilibrium, and excitation equilibrium in model atmospheres representative of both oxygen-rich and carbon-rich red giant stars is demonstrated. The radiative transfer and statistical equilibrium equations are solved self-consistently for H, H(-), H2, He I, C I, C II, Na I, Mg I, Mg II, Ca I, and Ca II in a plane-parallel static medium. Calculations are made for both radiative-equilibrium model photospheres alone and model photospheres with attached chromospheric models as determined semiempirically with IUE spectra of g Her (M6 III) and TX Psc (C6, 2). The excitation and ionization results for hydrogen and helium are reported.

Non-parallel divergence across freshwater and marine three-spined stickleback Gasterosteus aculeatus populations.

PubMed

Pujolar, J M; Ferchaud, A L; Bekkevold, D; Hansen, M M

2017-07-01

This work investigated whether multiple freshwater populations of three-spined stickleback Gasterosteus aculeatus in different freshwater catchments in the Jutland Peninsula, Denmark, derived from the same marine populations show repeated adaptive responses. A total of 327 G. aculeatus collected at 13 sampling locations were screened for genetic variation using a combination of 70 genes putatively under selection and 26 neutral genes along with a marker linked to the ectodysplasin gene (eda), which is strongly correlated with plate armour morphs in the species. A highly significant genetic differentiation was found that was higher among different freshwater samples than between marine-freshwater samples. Tests for selection between marine and freshwater populations showed a very low degree of parallelism and no single nucleotide polymorphism was detected as outlier in all freshwater-marine pairwise comparisons, including the eda. This suggests that G. aculeatus is not necessarily the prime example of parallel local adaptation suggested in much of the literature and that important exceptions exist (i.e. the Jutland Peninsula). While marine populations in the results described here showed a high phenotype-genotype correlation at eda, a low association was found for most of the freshwater populations. The most extreme case was found in the freshwater Lake Hald where all low-plated phenotypes were either homozygotes for the allele supposed to be associated with completely plated morphs or heterozygotes, but none were homozygotes for the putative low-plated allele. Re-examination of data from seven G. aculeatus studies agrees in showing a high but partial association between phenotype-genotype at eda in G. aculeatus freshwater populations and that mismatches occur everywhere in the European regions studied (higher in some areas, i.e. Denmark). This is independent of the eda marker used. © 2017 The Fisheries Society of the British Isles.

Theoretical model of the helium zone plate microscope

NASA Astrophysics Data System (ADS)

Salvador Palau, Adrià; Bracco, Gianangelo; Holst, Bodil

2017-01-01

Neutral helium microscopy is a new technique currently under development. Its advantages are the low energy, charge neutrality, and inertness of the helium atoms, a potential large depth of field, and the fact that at thermal energies the helium atoms do not penetrate into any solid material. This opens the possibility, among others, for the creation of an instrument that can measure surface topology on the nanoscale, even on surfaces with high aspect ratios. One of the most promising designs for helium microscopy is the zone plate microscope. It consists of a supersonic expansion helium beam collimated by an aperture (skimmer) focused by a Fresnel zone plate onto a sample. The resolution is determined by the focal spot size, which depends on the size of the skimmer, the optics of the system, and the velocity spread of the beam through the chromatic aberrations of the zone plate. An important factor for the optics of the zone plate is the width of the outermost zone, corresponding to the smallest opening in the zone plate. The width of the outermost zone is fabrication limited to around 10 nm with present-day state-of-the-art technology. Due to the high ionization potential of neutral helium atoms, it is difficult to build efficient helium detectors. Therefore, it is crucial to optimize the microscope design to maximize the intensity for a given resolution and width of the outermost zone. Here we present an optimization model for the helium zone plate microscope. Assuming constant resolution and width of the outermost zone, we are able to reduce the problem to a two-variable problem (zone plate radius and object distance) and we show that for a given beam temperature and pressure, there is always a single intensity maximum. We compare our model with the highest-resolution zone plate focusing images published and show that the intensity can be increased seven times. Reducing the width of the outermost zone to 10 nm leads to an increase in intensity of more than 8000 times. Finally, we show that with present-day state-of-the-art detector technology (ionization efficiency 1 ×10-3 ), a resolution of the order of 10 nm is possible. In order to make this quantification, we have assumed a Lambertian reflecting surface and calculated the beam spot size that gives a signal 100 cts/s within a solid angle of 0.02 sr, following an existing helium microscope design.

Detection of antimicrobial resistance-associated proteins by titanium dioxide-facilitated intact bacteria mass spectrometry† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c7sc04089j

PubMed Central

Zhu, Yingdi; Gasilova, Natalia; Jović, Milica; Qiao, Liang; Liu, Baohong; Lovey, Lysiane Tissières; Pick, Horst

2018-01-01

Titanium dioxide-modified target plates were developed to enhance intact bacteria analysis by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The plates were designed to photocatalytically destroy the bacterial envelope structure and improve the ionization efficiency of intracellular components, thereby promoting the measurable mass range and the achievable detection sensitivity. Accordingly, a method for rapid detection of antimicrobial resistance-associated proteins, conferring bacterial resistance against antimicrobial drugs, was established by mass spectrometric fingerprinting of intact bacteria without the need for any sample pre-treatment. With this method, the variations in resistance proteins’ expression levels within bacteria were quickly measured from the relative peak intensities. This approach of resistance protein detection directly from intact bacteria by mass spectrometry is useful for fast discrimination of antimicrobial-resistant bacteria from their non-resistant counterparts whilst performing species identification. Also, it could be used as a rapid and convenient way for initial determination of the underlying resistance mechanisms. PMID:29719694

Self-propulsion of Leidenfrost Drops between Non-Parallel Structures.

PubMed

Luo, Cheng; Mrinal, Manjarik; Wang, Xiang

2017-09-20

In this work, we explored self-propulsion of a Leidenfrost drop between non-parallel structures. A theoretical model was first developed to determine conditions for liquid drops to start moving away from the corner of two non-parallel plates. These conditions were then simplified for the case of a Leidenfrost drop. Furthermore, ejection speeds and travel distances of Leidenfrost drops were derived using a scaling law. Subsequently, the theoretical models were validated by experiments. Finally, three new devices have been developed to manipulate Leidenfrost drops in different ways.

Multipactor saturation in parallel-plate waveguides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sorolla, E.; Mattes, M.

2012-07-15

The saturation stage of a multipactor discharge is considered of interest, since it can guide towards a criterion to assess the multipactor onset. The electron cloud under multipactor regime within a parallel-plate waveguide is modeled by a thin continuous distribution of charge and the equations of motion are calculated taking into account the space charge effects. The saturation is identified by the interaction of the electron cloud with its image charge. The stability of the electron population growth is analyzed and two mechanisms of saturation to explain the steady-state multipactor for voltages near above the threshold onset are identified. Themore » impact energy in the collision against the metal plates decreases during the electron population growth due to the attraction of the electron sheet on the image through the initial plate. When this growth remains stable till the impact energy reaches the first cross-over point, the electron surface density tends to a constant value. When the stability is broken before reaching the first cross-over point the surface charge density oscillates chaotically bounded within a certain range. In this case, an expression to calculate the maximum electron surface charge density is found whose predictions agree with the simulations when the voltage is not too high.« less

Right/left assignment in drift chambers and proportional multiwire chambers (PWC's) using induced signals

DOEpatents

Walenta, Albert H.

1979-01-01

Improved multiwire chamber having means for resolving the left/right ambiguity in the location of an ionizing event. The chamber includes a plurality of spaced parallel anode wires positioned between spaced planar cathodes. Associated with each of the anode wires are a pair of localizing wires, one positioned on either side of the anode wire. The localizing wires are connected to a differential amplifier whose output polarity is determined by whether the ionizing event occurs to the right or left of the anode wire.

Flow-induced attraction of swimming microorganisms by surfaces

NASA Astrophysics Data System (ADS)

Lauga, Eric; Berke, Allison; Turner, Linda; Berg, Howard

2008-03-01

In this talk, we present an experimental and theoretical investigation of the accumulation of swimming cells by nearby surfaces. First, we present results of an experiment aiming at measuring the distribution of smooth-swimming E. coli when moving in a density-matched fluid and between two glass plates; the distribution for the bacteria concentration is found to peak near the glass plates. We then present a physical model for the observed attraction, based on the hydrodynamics interactions between the swimming cells and the walls. We show that such interactions result in a reorientation of the cells in the direction parallel to the surfaces, and an attraction of these (parallel) cells by the nearest wall. Our results are exploited to obtain an estimate of the propulsive force of smooth-swimming E. coli.

Use of PZT's for adaptive control of Fabry-Perot etalon plate figure

NASA Technical Reports Server (NTRS)

Skinner, WIlbert; Niciejewski, R.

2005-01-01

A Fabry Perot etalon, consisting of two spaced and reflective glass flats, provides the mechanism by which high resolution spectroscopy may be performed over narrow spectral regions. Space based applications include direct measurements of Doppler shifts of airglow absorption and emission features and the Doppler broadening of spectral lines. The technique requires a high degree of parallelism between the two flats to be maintained through harsh launch conditions. Monitoring and adjusting the plate figure by illuminating the Fabry Perot interferometer with a suitable monochromatic source may be performed on orbit to actively control of the parallelism of the flats. This report describes the use of such a technique in a laboratory environment applied to a piezo-electric stack attached to the center of a Fabry Perot etalon.

Evaluation of RANS and LES models for Natural Convection in High-Aspect-Ratio Parallel Plate Channels

NASA Astrophysics Data System (ADS)

Fradeneck, Austen; Kimber, Mark

2017-11-01

The present study evaluates the effectiveness of current RANS and LES models in simulating natural convection in high-aspect ratio parallel plate channels. The geometry under consideration is based on a simplification of the coolant and bypass channels in the very high-temperature gas reactor (VHTR). Two thermal conditions are considered, asymmetric and symmetric wall heating with an applied heat flux to match Rayleigh numbers experienced in the VHTR during a loss of flow accident (LOFA). RANS models are compared to analogous high-fidelity LES simulations. Preliminary results demonstrate the efficacy of the low-Reynolds number k- ɛ formulations and their enhancement to the standard form and Reynolds stress transport model in terms of calculating the turbulence production due to buoyancy and overall mean flow variables.

Fabrication of self-aligned, nanoscale, complex oxide varactors

NASA Astrophysics Data System (ADS)

Fu, Richard X.; Toonen, Ryan C.; Hirsch, Samuel G.; Ivill, Mathew P.; Cole, Melanie W.; Strawhecker, Kenneth E.

2015-01-01

Applications in ferroelectric random access memory and superparaelectric devices require the fabrication of ferroelectric capacitors at the nanoscale that exhibit extremely small leakage currents. To systematically study the material-size dependence of ferroelectric varactor performance, arrays of parallel-plate structures have been fabricated with nanoscale dielectric diameters. Electron beam lithography and inductively coupled plasma dry etching have been used to fabricate arrays of ferroelectric varactors using top electrodes as a self-aligned etch mask. Parallel-plate test structures using RF-sputtered Ba0.6Sr0.4TiO3 thin-films were used to optimize the fabrication process. Varactors with diameters down to 20 nm were successfully fabricated. Current-voltage (I-V) characteristics were measured to evaluate the significance of etch-damage and fabrication quality by ensuring low leakage currents through the structures.

Apparatus for suppressing formation of vortices in the coolant fluid of a nuclear reactor and associated method

DOEpatents

Ekeroth, D.E.; Garner, D.C.; Hopkins, R.J.; Land, J.T.

1993-11-30

An apparatus and method are provided for suppressing the formation of vortices in circulating coolant fluid of a nuclear reactor. A vortex-suppressing plate having a plurality of openings therein is suspended within the lower plenum of a reactor vessel below and generally parallel to the main core support of the reactor. The plate is positioned so as to intersect vortices which may form in the circulating reactor coolant fluid. The intersection of the plate with such vortices disrupts the rotational flow pattern of the vortices, thereby disrupting the formation thereof. 3 figures.

Apparatus for suppressing formation of vortices in the coolant fluid of a nuclear reactor and associated method

DOEpatents

Ekeroth, Douglas E.; Garner, Daniel C.; Hopkins, Ronald J.; Land, John T.

1993-01-01

An apparatus and method are provided for suppressing the formation of vortices in circulating coolant fluid of a nuclear reactor. A vortex-suppressing plate having a plurality of openings therein is suspended within the lower plenum of a reactor vessel below and generally parallel to the main core support of the reactor. The plate is positioned so as to intersect vortices which may form in the circulating reactor coolant fluid. The intersection of the plate with such vortices disrupts the rotational flow pattern of the vortices, thereby disrupting the formation thereof.

Nuclear reactor fuel structure containing uranium alloy wires embedded in a metallic matrix plate

DOEpatents

Travelli, A.

1985-10-25

A flat or curved plate structure, to be used as fuel in a nuclear reactor, comprises elongated fissionable wires or strips embedded in a metallic continuous non-fissionable matrix plate. The wires or strips are made predominantly of a malleable uranium alloy, such as uranium silicide, uranium gallide or uranium germanide. The matrix plate is made predominantly of aluminum or an aluminum alloy. The wires or strips are located in a single row at the midsurface of the plate, parallel with one another and with the length dimension of the plate. The wires or strips are separated from each other, and from the surface of the plate, by sufficient thicknesses of matrix material, to provide structural integrity and effective fission product retention, under neutron irradiation. This construction makes it safely feasible to provide a high uranium density, so that the uranium enrichment with uranium 235 may be reduced below about 20%, to deter the reprocessing of the uranium for use in nuclear weapons.

Nuclear reactor fuel structure containing uranium alloy wires embedded in a metallic matrix plate

DOEpatents

Travelli, Armando

1988-01-01

A flat or curved plate structure, to be used as fuel in a nuclear reactor, comprises elongated fissionable wires or strips embedded in a metallic continuous non-fissionable matrix plate. The wires or strips are made predominantly of a malleable uranium alloy, such as uranium silicide, uranium gallide or uranium germanide. The matrix plate is made predominantly of aluminum or an aluminum alloy. The wires or strips are located in a single row at the midsurface of the plate, parallel with one another and with the length dimension of the plate. The wires or strips are separated from each other, and from the surface of the plate, by sufficient thicknesses of matrix material, to provide structural integrity and effective fission product retention, under neutron irradiation. This construction makes it safely feasible to provide a high uranium density, so that the uranium enrichment with uranium 235 may be reduced below about 20%, to deter the reprocessing of the uranium for use in nuclear weapons.

Biomechanics of far cortical locking.

PubMed

Bottlang, Michael; Feist, Florian

2011-02-01

The development of far cortical locking (FCL) was motivated by a conundrum: locked plating constructs provide inherently rigid stabilization, yet they should facilitate biologic fixation and secondary bone healing that relies on flexible fixation to stimulate callus formation. Recent studies have confirmed that the high stiffness of standard locked plating constructs can suppress interfragmentary motion to a level that is insufficient to reliably promote secondary fracture healing by callus formation. Furthermore, rigid locking screws cause an uneven stress distribution that may lead to stress fracture at the end screw and stress shielding under the plate. This review summarizes four key features of FCL constructs that have been shown to enhance fixation and healing of fractures: flexible fixation, load distribution, progressive stiffening, and parallel interfragmentary motion. Specifically, flexible fixation provided by FCL reduces the stiffness of a locked plating construct by 80% to 88% to actively promote callus proliferation similar to an external fixator. Load is evenly distributed between FCL screws to mitigate stress risers at the end screw. Progressive stiffening occurs by near cortex support of FCL screws and provides additional support under elevated loading. Finally, parallel interfragmentary motion by the S-shaped flexion of FCL screws promotes symmetric callus formation. In combination, these features of FCL constructs have been shown to induce more callus and to yield significantly stronger and more consistent healing compared with standard locked plating constructs. As such, FCL constructs function as true internal fixators by replicating the biomechanical behavior and biologic healing response of external fixators.

Biomechanics of Far Cortical Locking

PubMed Central

Bottlang, Michael; Feist, Florian

2011-01-01

The development of FCL was motivated by a conundrum: locked plating constructs provide inherently rigid stabilization, yet they should facilitate biological fixation and secondary bone healing that relies on flexible fixation to stimulate callus formation. Recent studies have confirmed that the high stiffness of standard locked plating constructs can suppress interfragmentary motion to a level that is insufficient to reliably promote secondary fracture healing by callus formation. Furthermore, rigid locking screws cause an uneven stress distribution that may lead to stress fracture at the end screw and stress shielding under the plate. This review summarizes four key features of FCL constructs that have shown to enhance fixation and fracture healing: Flexible fixation, load distribution, progressive stiffening, and parallel interfragmentary motion. Specifically, flexible fixation provided by FCL reduces the stiffness of a locked plating construct by 80–88% to actively promote callus proliferation similar to an external fixator. Load distribution is evenly shared between FCL screws to mitigate stress risers at the end screw. Progressive stiffening occurs by near cortex support of FCL screws and provides additional support under elevated loading. Finally, parallel interfragmentary motion by s-shaped flexion of FCL screws has shown to induce symmetric callus formation. In combination, these features of FCL constructs have shown to induce more callus and to yield significantly stronger and more consistent healing compared to standard locked plating constructs. As such, FCL constructs function as true internal fixators by replicating the biomechanical behavior and biological healing response of external fixators. PMID:21248556

Subduction Thermal Regime, Slab Dehydration, and Seismicity Distribution Beneath Hikurangi Based on 3-D Simulations

NASA Astrophysics Data System (ADS)

Suenaga, Nobuaki; Ji, Yingfeng; Yoshioka, Shoichi; Feng, Deshan

2018-04-01

The downdip limit of seismogenic interfaces inferred from the subduction thermal regime by thermal models has been suggested to relate to the faulting instability caused by the brittle failure regime in various plate convergent systems. However, the featured three-dimensional thermal state, especially along the horizontal (trench-parallel) direction of a subducted oceanic plate, remains poorly constrained. To robustly investigate and further map the horizontal (trench-parallel) distribution of the subduction regime and subsequently induced slab dewatering in a descending plate beneath a convergent margin, we construct a regional thermal model that incorporates an up-to-date three-dimensional slab geometry and the MORVEL plate velocity to simulate the plate subduction history in Hikurangi. Our calculations suggest an identified thrust zone featuring remarkable slab dehydration near the Taupo volcanic arc in the North Island distributed in the Kapiti, Manawatu, and Raukumara region. The calculated average subduction-associated slab dehydration of 0.09 to 0.12 wt%/km is greater than the dehydration in other portions of the descending slab and possibly contributes to an along-arc variation in the interplate pore fluid pressure. A large-scale slab dehydration (>0.05 wt%/km) and a high thermal gradient (>4 °C/km) are also identified in the Kapiti, Manawatu, and Raukumara region and are associated with frequent deep slow slip events. An intraslab dehydration that exceeds 0.2 wt%/km beneath Manawatu near the source region of tectonic tremors suggests an unknown relationship in the genesis of slow earthquakes.

Reaction Force of Micro-scale Liquid Droplets Constrained Between Parallel Plates through CFD

NASA Astrophysics Data System (ADS)

Free, Robert; Hekiri, Haider; Hawa, Takumi

2012-02-01

Micro-scale liquid droplets responding to depression between parallel plates are investigated analytically and numerically. The functional dependence of the reaction force accrued in such droplets on droplet size, surface tension, depression amount, and contact angle is explored. For both the 2D and 3D case, an analytical model is developed based on first principles. Computational fluid dynamics is then utilized to evaluate the validity of these models. The reaction force is highly nonlinear, initially increasing very slowly with increasing depression of the droplet, but eventually moving asymptotically to infinity. The force scales linearly with both the droplet free radius and surface tension of the liquid, but has a much more complicated dependence on the contact angle and depression. Explicit expressions for the reaction force have been determined, showing these dependencies. The 3D model has been largely supported by the CFD results. It very accurately predicts the reaction force on the upper plate as the droplet is crushed, accounting for the effect of contact angle, surface tension, and droplet size.

Glass matrix armor

DOEpatents

Calkins, Noel C.

1991-01-01

An armor system which utilizes glass. A plurality of constraint cells are mounted on a surface of a substrate, which is metal armor plate or a similar tough material, such that the cells almost completely cover the surface of the substrate. Each constraint cell has a projectile-receiving wall parallel to the substrate surface and has sides which are perpendicular to and surround the perimeter of the receiving wall. The cells are mounted such that, in one embodiment, the substrate surface serves as a sixth side or closure for each cell. Each cell has inside of it a plate, termed the front plate, which is parallel to and in contact with substantially all of the inside surface of the receiving wall. The balance of each cell is completely filled with a projectile-abrading material consisting of glass and a ceramic material and, in certain embodiments, a polymeric material. The glass may be in monolithic form or particles of ceramic may be dispersed in a glass matrix. The ceramic material may be in monolithic form or may be in the form of particles dispersed in glass or dispersed in said polymer.

Architecture for Absorption Based Heaters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moghaddam, Saeed; Chugh, Devesh

An absorption based heater is constructed on a fluid barrier heat exchanging plate such that it requires little space in a structure. The absorption based heater has a desorber, heat exchanger, and absorber sequentially placed on the fluid barrier heat exchanging plate. The vapor exchange faces of the desorber and the absorber are covered by a vapor permeable membrane that is permeable to a refrigerant vapor but impermeable to an absorbent. A process fluid flows on the side of the fluid barrier heat exchanging plate opposite the vapor exchange face through the absorber and subsequently through the heat exchanger. Themore » absorption based heater can include a second plate with a condenser situated parallel to the fluid barrier heat exchanging plate and opposing the desorber for condensation of the refrigerant for additional heating of the process fluid.« less

Control of the pattern of perithecium development in Sordaria fimicola on agar medium.

PubMed

Pollock, R T

1975-06-01

In a Sordaria fimicola (Rob.) Ces. and de Not. colony grown on agar medium in a petri plate, perithecia developed in a narrow band around the plate edge after the colony margin reached the edge. Physical wounding of the colony carried out shortly before or during the time perithecia were developing around the plate edge stimulated perithecium development in the wound area. Diffusion barriers were created by cutting small trenches in the agar parallel to the plate edge. The trenches were made at several different positions between the plate center and edge using cultures of several different ages, and the resultant distribution of perithecia along the trench edges suggested that the colony center and periphery produce diffusible inhibitors of perithecium development. These inhibitors may be responsible, in part, for the observed pattern of perithecium development in the colony.

Seismic evidence for convection-driven motion of the North American plate.

PubMed

Eaton, David W; Frederiksen, Andrew

2007-03-22

Since the discovery of plate tectonics, the relative importance of driving forces of plate motion has been debated. Resolution of this issue has been hindered by uncertainties in estimates of basal traction, which controls the coupling between lithospheric plates and underlying mantle convection. Hotspot tracks preserve records of past plate motion and provide markers with which the relative motion between a plate's surface and underlying mantle regions may be examined. Here we show that the 115-140-Myr surface expression of the Great Meteor hotspot track in eastern North America is misaligned with respect to its location at 200 km depth, as inferred from plate-reconstruction models and seismic tomographic studies. The misalignment increases with age and is consistent with westward displacement of the base of the plate relative to its surface, at an average rate of 3.8 +/- 1.8 mm yr(-1). Here age-constrained 'piercing points' have enabled direct estimation of relative motion between the surface and underside of a plate. The relative displacement of the base is approximately parallel to seismic fast axes and calculated mantle flow, suggesting that asthenospheric flow may be deforming the lithospheric keel and exerting a driving force on this part of the North American plate.

Forearc deformation and great subduction earthquakes: implications for cascadia offshore earthquake potential.

PubMed

McCaffrey, R; Goldfinger, C

1995-02-10

The maximum size of thrust earthquakes at the world's subduction zones appears to be limited by anelastic deformation of the overriding plate. Anelastic strain in weak forearcs and roughness of the plate interface produced by faults cutting the forearc may limit the size of thrust earthquakes by inhibiting the buildup of elastic strain energy or slip propagation or both. Recently discovered active strike-slip faults in the submarine forearc of the Cascadia subduction zone show that the upper plate there deforms rapidly in response to arc-parallel shear. Thus, Cascadia, as a result of its weak, deforming upper plate, may be the type of subduction zone at which great (moment magnitude approximately 9) thrust earthquakes do not occur.

Broad band antennas and feed methods

DOE Office of Scientific and Technical Information (OSTI.GOV)

Benzel, David M.; Twogood, Richard E.

Two or more Vivaldi antennas, consisting of two plates each, each with the antenna's natural impedance of approximately 100 ohms, are placed in parallel to achieve a 50 ohm impedance in the case of two antennas or other impedances (100/n ohms) for more than two antennas. A single Vivaldi antenna plate (half Vivaldi antenna) over a ground plane can also be used to achieve a 50 ohm impedance, or two or more single plates over a ground plane to achieve other impedances. Unbalanced 50 ohm transmission lines, e.g. coaxial cables, can be used to directly feed, the dual Vivaldi (fourmore » plate) antenna in a center fed angled center departure, or more desirably, a center fed offset departure configuration.« less

[A case control study of perpendicular or parallel double plate for the treatment of young and middle-aged patients with type C fractures of distal humerus].

PubMed

Yu, Ye-Feng; Dai, Jia-Ping; Sheng, Jian-Ming; Zhou, Xiao

2017-06-25

To compare clinical outcomes of perpendicular or parallel double plate in treating type C fractures of distal humerus in adults. From March 2009 and March 2013, 40 adult patients with type C distal humerus fractures were treated. The patients were divided into two groups according to fixed form. In perpendicular group(group A), there were 13 males and 9 females with a mean age of (37.56±9.24) years old(ranged 18 to 56);while in parallel plating group(group B), including 11 males and 7 females, with a mean age of (41.35±9.03) year old(ranged 20 to 53). All fractures were fresh and closed without blood vessels or nerve damaged. Incision length, operating time, blood loss, hospital stay, preoperative and postoperative radiological change, range of activity of elbow joint, Mayo score, flexor and extensor elbow strength, and postoperative complications were observed and compared. All incisions were healed well. One patient occurred myositis ossificans between two groups. Two patients in group A and 1 patient in group B occurred elbow joint stiffness. All fractures were obtained bone union. Group A were followed up from 20 to 36 months with an average of (25.2±7.1) months, while group B were followed up from 18 to 35 months with an average of(24.3±6.0) months. There were significant differences in blood loss and operative time, while there was no obvious meaning in incision length, hospital stay, muscle strength, fracture healing time, range of activity of elbow joint. Mayo score of group A was 82.27±10.43, 6 cases obtained excellent results, 12 good, 3 moderate and 1 poor;in group B was 81.94±12.02, 5 cases obtained excellent results, 9 good, 3 moderate and 1 poor;and there were no statistical significance between two groups. There was no significant differences in clinical effects between perpendicular and parallel double plate for adult patients with type C distal humerus fractures, while the operation should choose according to facture and proficiency of operator.

Development of radiation tolerant monolithic active pixel sensors with fast column parallel read-out

NASA Astrophysics Data System (ADS)

Koziel, M.; Dorokhov, A.; Fontaine, J.-C.; De Masi, R.; Winter, M.

2010-12-01

Monolithic active pixel sensors (MAPS) [1] (Turchetta et al., 2001) are being developed at IPHC—Strasbourg to equip the EUDET telescope [2] (Haas, 2006) and vertex detectors for future high energy physics experiments, including the STAR upgrade at RHIC [3] (T.S. Collaboration, 2005) and the CBM experiment at FAIR/GSI [4] (Heuser, 2006). High granularity, low material budget and high read-out speed are systematically required for most applications, complemented, for some of them, with high radiation tolerance. A specific column-parallel architecture, implemented in the MIMOSA-22 sensor, was developed to achieve fast read-out MAPS. Previous studies of the front-end architecture integrated in this sensor, which includes in-pixel amplification, have shown that the fixed pattern noise increase consecutive to ionizing radiation can be controlled by means of a negative feedback [5] (Hu-Guo et al., 2008). However, an unexpected rise of the temporal noise was observed. A second version of this chip (MIMOSA-22bis) was produced in order to search for possible improvements of the radiation tolerance, regarding this type of noise. In this prototype, the feedback transistor was tuned in order to mitigate the sensitivity of the pixel to ionizing radiation. The performances of the pixels after irradiation were investigated for two types of feedback transistors: enclosed layout transistor (ELT) [6] (Snoeys et al., 2000) and "standard" transistor with either large or small transconductance. The noise performance of all test structures was studied in various conditions (expected in future experiments) regarding temperature, integration time and ionizing radiation dose. Test results are presented in this paper. Based on these observations, ideas for further improvement of the radiation tolerance of column parallel MAPS are derived.

Influence of the pH value of a colloidal gold solution on the absorption spectra of an LSPR-assisted sensor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhu, Jin; Li, Wenbin; Zhu, Mao

2014-03-15

The localized surface plasmon resonances (LSPRs) of gold particles assembled on a crystal plate are a powerful tool for biological sensors. Here, we prepare gold colloids in different pH solutions. We monitor the effects of the particle radius and particle coverage on the absorption spectra of AT-cut (r-face dihedral angle of about 3°) crystal plates supporting gold nanoparticles. The surface morphologies were monitored on silicon dioxide substrates using ultraviolet and visible (UV-vis) spectroscopy, and atomic force microscopy (AFM). The results showed that the gold particle coverage decreases with increasing pH value of the gold colloid solution. This phenomenon demonstrates thatmore » self-assembled gold surfaces were formed via the electrostatic adsorption of gold particles on the positively charged, ionized amino groups on the crystal plates in the acidic solution. The spectrum of gold nanoparticles with different coverage degree on the crystal plates showed that the LSPR properties are highly dependent on pH.« less

Hugoniot measurements of double-shocked precompressed dense xenon plasmas

NASA Astrophysics Data System (ADS)

Zheng, J.; Chen, Q. F.; Gu, Y. J.; Chen, Z. Y.

2012-12-01

The current partially ionized plasmas models for xenon show substantial differences since the description of pressure and thermal ionization region becomes a formidable task, prompting the need for an improved understanding of dense xenon plasmas behavior at above 100 GPa. We performed double-shock compression experiments on dense xenon to determine accurately the Hugoniot up to 172 GPa using a time-resolved optical radiation method. The planar strong shock wave was produced using a flyer plate impactor accelerated up to ˜6 km/s with a two-stage light-gas gun. The time-resolved optical radiation histories were acquired by using a multiwavelength channel optical transience radiance pyrometer. Shock velocity was measured and mass velocity was determined by the impedance-matching methods. The experimental equation of state of dense xenon plasmas are compared with the self-consistent fluid variational calculations of dense xenon in the region of partial ionization over a wide range of pressures and temperatures.

Composite glycerol/graphite/aromatic acid matrices for thin-layer chromatography/matrix-assisted laser desorption/ionization mass spectrometry of heterocyclic compounds.

PubMed

Esparza, Cesar; Borisov, R S; Varlamov, A V; Zaikin, V G

2016-10-28

New composite matrices have been suggested for the analysis of mixtures of different synthetic organic compounds (N-containing heterocycles and erectile dysfunction drugs) by thin layer chromatography/matrix-assisted laser desorption ionization time-of-flight mass spectrometry (TLC/MALDI-TOF). Different mixtures of classical MALDI matrices and graphite particles dispersed in glycerol were used for the registration of MALDI mass spectra directly from TLC plates after analytes separation. In most of cases, the mass spectra possessed [M+H] + ions; however, for some analytes only [M+Na] + and [M+K] + ions were observed. These ions have been used to generate visualized TLC chromatograms. The described approach increases the desorption/ionization efficiencies of analytes separated by TLC, prevent spot blurring, simplifies and decrease time for sample preparation. Copyright © 2016 Elsevier B.V. All rights reserved.

Identification of lipid- and protein-based binders in paintings by direct on-plate wet chemistry and matrix-assisted laser desorption ionization mass spectrometry.

PubMed

Calvano, Cosima Damiana; van der Werf, Inez Dorothé; Palmisano, Francesco; Sabbatini, Luigia

2015-01-01

Direct on-target plate processing of small (ca. 100 μg) fragments of paint samples for MALDI-MS identification of lipid- and protein-based binders is described. Fragments were fixed on a conventional stainless steel target plate by colloidal graphite followed by in situ fast tryptic digestion and matrix addition. The new protocol was first developed on paint replicas composed of chicken egg, collagen, and cow milk mixed with inorganic pigments and then successfully applied on historical paint samples taken from a fifteenth century Italian panel painting. The present work contributes a step forward in the simplification of binder identification in very small paint samples since no conventional solvent extraction is required, speeding up the whole sample preparation to 10 min and reducing lipid/protein loss.

Three-dimensional Numerical Models of the Cocos-northern Nazca Slab Gap

NASA Astrophysics Data System (ADS)

Jadamec, M.; Fischer, K. M.

2012-12-01

In contrast to anisotropy beneath the middle of oceanic plates, seismic observations in subduction zones often indicate mantle flow patterns that are not easily explained by simple coupling of the subducting and overriding plates to the mantle. For example, in the Costa Rica-Nicaragua subduction zone local S shear wave splitting measurements combined with geochemical data indicate trench parallel flow in the mantle wedge with flow rates of 6.3-19 cm/yr, which is on order of or may be up to twice the subducting plate velocity. We construct geographically referenced high-resolution three-dimensional (3D) geodynamic models of the Cocos-northern Nazca subduction system to investigate what is driving the northwest directed, and apparently rapid, trench-parallel flow in the mantle wedge beneath Costa Rica-Nicaragua. We use the SlabGenerator code to construct a 3D plate configuration that is used as input to the community mantle convection code, CitcomCU. Models are run on over 400 CPUs on XSEDE, with a mesh resolution of up to 3 km at the plate boundary. Seismicity and seismic tomography delineate the shape and depth of the Cocos and northern Nazca slabs. The subducting plate thermal structure is based on a plate cooling model and ages from the seafloor age grid. Overriding plate thickness is constrained by the ages from the sea floor age grid where available and the depth to the lithosphere-asthenosphere boundary from the greatest negative gradient in absolute shear wave velocity. The geodynamic models test the relative controls of the change in the dip of the Cocos plate and the slab gap between the Cocos and northern Nazca plates in driving the mantle flow beneath Central America. The models also investigate the effect of a non-Newtonian rheology in dynamically generating a low viscosity mantle wedge and how this controls mantle flow rates. To what extent the Cocos-northern Nazca slab gap channelizes mantle flow between Central and South America has direct application to geochemical and geologic studies of the region. In addition, 3D geodynamic models of this kind can further test the hypothesis of rapid mantle flow in subduction zones as a global process and the non-Newtonian rheology as a mechanism for decoupling the mantle from lithospheric plate motion.

Resistive Plate Chambers with Gd-coated electrodes as thermal neutron detectors

NASA Astrophysics Data System (ADS)

Abbrescia, M.; Iaselli, G.; Mongelli, T.; Paticchio, V.; Ranieri, A.; Trentadue, R.

2003-12-01

Resistive Plate Chambers (RPCs) are wide spread, cheap, easy-to-build and large size detectors, used mainly to reveal ionizing particles in high energy experiments. Here a tecnique, consisting in coating the inner surface of the bakelite electrodes with a mixture of linseed oil and Gd2O3 will be reported; this allows to make RPCs sensitive also to thermal neutrons, making them suitable to be employed for industrial, medical or de-ming applications. This new type, position sensitive gas detector can be operated at atmospheric pressure, is lightweighted, has low γ-ray sensitivity, and is easy to handle even when large areas are to be covered.

Neutron-Induced Fission Cross Section Measurements for Full Suite of Uranium Isotopes

NASA Astrophysics Data System (ADS)

Laptev, Alexander; Tovesson, Fredrik; Hill, Tony

2010-11-01

A well established program of neutron-induced fission cross section measurement at Los Alamos Neutron Science Center (LANSCE) is supporting the Fuel Cycle Research program (FC R&D). The incident neutron energy range spans energies from sub-thermal energies up to 200 MeV by measuring both the Lujan Center and the Weapons Neutron Research center (WNR). Conventional parallel-plate fission ionization chambers with actinide deposited foils are used as a fission detector. The time-of-flight method is implemented to measure neutron energy. Counting rate ratio from investigated and standard U-235 foils is translated into fission cross section ratio. Different methods of normalization for measured ratio are employed, namely, using of actinide deposit thicknesses, normalization to evaluated data, etc. Finally, ratios are converted to cross sections based on the standard U-235 fission cross section data file. Preliminary data for newly investigated isotopes U-236 and U-234 will be reported. Those new data complete a full suite of Uranium isotopes, which were investigated with presented experimental approach. When analysis of the new measured data will is completed, data will be delivered to evaluators. Having data for full set of Uranium isotopes will increase theoretical modeling capabilities and make new data evaluations much more reliable.

Temperature Dependence of Radiation Induced Conductivity in Insulators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dennison, J. R.; Gillespie, Jodie; Hodges, Joshua

2009-03-10

This study measures Radiation Induced Conductivity (RIC) of Low Density Polyethylene (LDPE) over temperatures ranging from {approx}110 K to {approx}350 K. RIC occurs when incident ionizing radiation deposits energy and excites electrons into the conduction band of insulators. Conductivity was measured when a voltage was applied across vacuum-baked, thin film LDPE polymer samples in a parallel plate geometry. RIC was calculated as the difference in sample conductivity under no incident radiation and under an incident {approx}4 MeV electron beam at low incident fluxes of 10{sup -4}-10{sup -1} Gr/sec. The steady-state RIC was found to agree well with the standard powermore » law relation, {sigma}{sub RIC} = k{sub RIC}{center_dot}D ring {sup {delta}} between conductivity, {sigma} and adsorbed dose rate, D ring . Both the proportionality constant, k{sub RIC}, and the power, {delta}, were found to be temperature dependant above {approx}250 K, with behavior consistent with photoconductivity models developed for localized trap states in disordered semiconductors. Below {approx}250 K, kRIC and {delta} exhibited little change. The observed difference in temperature dependence might be related to a structural phase transition seen at T{sub {beta}}{approx}256 K in prior studies of mechanical and thermodynamic properties of LDPE.« less

In vivo proton dosimetry using a MOSFET detector in an anthropomorphic phantom with tissue inhomogeneity.

PubMed

Kohno, Ryosuke; Hotta, Kenji; Matsubara, Kana; Nishioka, Shie; Matsuura, Taeko; Kawashima, Mitsuhiko

2012-03-08

When in vivo proton dosimetry is performed with a metal-oxide semiconductor field-effect transistor (MOSFET) detector, the response of the detector depends strongly on the linear energy transfer. The present study reports a practical method to correct the MOSFET response for linear energy transfer dependence by using a simplified Monte Carlo dose calculation method (SMC). A depth-output curve for a mono-energetic proton beam in polyethylene was measured with the MOSFET detector. This curve was used to calculate MOSFET output distributions with the SMC (SMC(MOSFET)). The SMC(MOSFET) output value at an arbitrary point was compared with the value obtained by the conventional SMC(PPIC), which calculates proton dose distributions by using the depth-dose curve determined by a parallel-plate ionization chamber (PPIC). The ratio of the two values was used to calculate the correction factor of the MOSFET response at an arbitrary point. The dose obtained by the MOSFET detector was determined from the product of the correction factor and the MOSFET raw dose. When in vivo proton dosimetry was performed with the MOSFET detector in an anthropomorphic phantom, the corrected MOSFET doses agreed with the SMC(PPIC) results within the measurement error. To our knowledge, this is the first report of successful in vivo proton dosimetry with a MOSFET detector.

Data Parallel Line Relaxation (DPLR) Code User Manual: Acadia - Version 4.01.1

NASA Technical Reports Server (NTRS)

Wright, Michael J.; White, Todd; Mangini, Nancy

2009-01-01

Data-Parallel Line Relaxation (DPLR) code is a computational fluid dynamic (CFD) solver that was developed at NASA Ames Research Center to help mission support teams generate high-value predictive solutions for hypersonic flow field problems. The DPLR Code Package is an MPI-based, parallel, full three-dimensional Navier-Stokes CFD solver with generalized models for finite-rate reaction kinetics, thermal and chemical non-equilibrium, accurate high-temperature transport coefficients, and ionized flow physics incorporated into the code. DPLR also includes a large selection of generalized realistic surface boundary conditions and links to enable loose coupling with external thermal protection system (TPS) material response and shock layer radiation codes.

Energetic particle diffusion coefficients upstream of quasi-parallel interplanetary shocks

NASA Technical Reports Server (NTRS)

Tan, L. C.; Mason, G. M.; Gloeckler, G.; Ipavich, F. M.

1989-01-01

The properties of about 30 to 130-keV/e protons and alpha particles upstream of six quasi-parallel interplanetary shocks that passed by the ISEE 3 spacecraft during 1978-1979 were analyzed, and the values for the upstream energegic particle diffusion coefficient, kappa, in these six events were deduced for a number of energies and upstream positions. These observations were compared with predictions of Lee's (1983) theory of shock acceleration. It was found that the observations verified the prediction of the A/Q dependence (where A and Q are the particle atomic mass and ionization state, respectively) of kappa for alpha and proton particles upstream of the quasi-parallel shocks.

Controlling nonsequential double ionization of Ne with parallel-polarized two-color laser pulses.

PubMed

Luo, Siqiang; Ma, Xiaomeng; Xie, Hui; Li, Min; Zhou, Yueming; Cao, Wei; Lu, Peixiang

2018-05-14

We measure the recoil-ion momentum distributions from nonsequential double ionization of Ne by two-color laser pulses consisting of a strong 800-nm field and a weak 400-nm field with parallel polarizations. The ion momentum spectra show pronounced asymmetries in the emission direction, which depend sensitively on the relative phase of the two-color components. Moreover, the peak of the doubly charged ion momentum distribution shifts gradually with the relative phase. The shifted range is much larger than the maximal vector potential of the 400-nm laser field. Those features are well recaptured by a semiclassical model. Through analyzing the correlated electron dynamics, we found that the energy sharing between the two electrons is extremely unequal at the instant of recollison. We further show that the shift of the ion momentum corresponds to the change of the recollision time in the two-color laser field. By tuning the relative phase of the two-color components, the recollision time is controlled with attosecond precision.

Microplasma discharge vacuum ultraviolet photoionization source for atmospheric pressure ionization mass spectrometry.

PubMed

Symonds, Joshua M; Gann, Reuben N; Fernández, Facundo M; Orlando, Thomas M

2014-09-01

In this paper, we demonstrate the first use of an atmospheric pressure microplasma-based vacuum ultraviolet (VUV) photoionization source in atmospheric pressure mass spectrometry applications. The device is a robust, easy-to-operate microhollow cathode discharge (MHCD) that enables generation of VUV photons from Ne and Ne/H(2) gas mixtures. Photons were detected by excitation of a microchannel plate detector and by analysis of diagnostic sample ions using a mass spectrometer. Reactive ions, charged particles, and metastables produced in the discharge were blocked from entering the ionization region by means of a lithium fluoride window, and photoionization was performed in a nitrogen-purged environment. By reducing the output pressure of the MHCD, we observed heightened production of higher-energy photons, making the photoionization source more effective. The initial performance of the MHCD VUV source has been evaluated by ionizing model analytes such as acetone, azulene, benzene, dimethylaniline, and glycine, which were introduced in solid or liquid phase. These molecules represent species with both high and low proton affinities, and ionization energies ranging from 7.12 to 9.7 eV.

Evaluation of hydraulic plate compactor.

DOT National Transportation Integrated Search

2014-12-01

This report presents the results of two parallel field investigations consisting of utility trench backfill compaction tests. The field : investigation at State College, Pa. was conducted to establish baseline measurements using a walk-behind vibrato...

Coupled microwave ECR and radio-frequency plasma source for plasma processing

DOEpatents

Tsai, Chin-Chi; Haselton, Halsey H.

1994-01-01

In a dual plasma device, the first plasma is a microwave discharge having its own means of plasma initiation and control. The microwave discharge operates at electron cyclotron resonance (ECR), and generates a uniform plasma over a large area of about 1000 cm.sup.2 at low pressures below 0.1 mtorr. The ECR microwave plasma initiates the second plasma, a radio frequency (RF) plasma maintained between parallel plates. The ECR microwave plasma acts as a source of charged particles, supplying copious amounts of a desired charged excited species in uniform manner to the RF plasma. The parallel plate portion of the apparatus includes a magnetic filter with static magnetic field structure that aids the formation of ECR zones in the two plasma regions, and also assists in the RF plasma also operating at electron cyclotron resonance.

Coupled microwave ECR and radio-frequency plasma source for plasma processing

DOEpatents

Tsai, C.C.; Haselton, H.H.

1994-03-08

In a dual plasma device, the first plasma is a microwave discharge having its own means of plasma initiation and control. The microwave discharge operates at electron cyclotron resonance (ECR), and generates a uniform plasma over a large area of about 1000 cm[sup 2] at low pressures below 0.1 mtorr. The ECR microwave plasma initiates the second plasma, a radio frequency (RF) plasma maintained between parallel plates. The ECR microwave plasma acts as a source of charged particles, supplying copious amounts of a desired charged excited species in uniform manner to the RF plasma. The parallel plate portion of the apparatus includes a magnetic filter with static magnetic field structure that aids the formation of ECR zones in the two plasma regions, and also assists in the RF plasma also operating at electron cyclotron resonance. 4 figures.

Active strike-slip faulting in El Salvador, Central America

NASA Astrophysics Data System (ADS)

Corti, Giacomo; Carminati, Eugenio; Mazzarini, Francesco; Oziel Garcia, Marvyn

2005-12-01

Several major earthquakes have affected El Salvador, Central America, during the Past 100 yr as a consequence of oblique subduction of the Cocos plate under the Caribbean plate, which is partitioned between trench-orthogonal compression and strike-slip deformation parallel to the volcanic arc. Focal mechanisms and the distribution of the most destructive earthquakes, together with geomorphologic evidence, suggest that this transcurrent component of motion may be accommodated by a major strike-slip fault (El Salvador fault zone). We present field geological, structural, and geomorphological data collected in central El Salvador that allow the constraint of the kinematics and the Quaternary activity of this major seismogenic strike-slip fault system. Data suggest that the El Salvador fault zone consists of at least two main ˜E-W fault segments (San Vicente and Berlin segments), with associated secondary synthetic (WNW-ESE) and antithetic (NNW-SSE) Riedel shears and NW-SE tensional structures. The two main fault segments overlap in a dextral en echelon style with the formation of an intervening pull-apart basin. Our original geological and geomorphologic data suggest a late Pleistocene Holocene slip rate of ˜11 mm/yr along the Berlin segment, in contrast with low historical seismicity. The kinematics and rates of deformation suggested by our new data are consistent with models involving slip partitioning during oblique subduction, and support the notion that a trench-parallel component of motion between the Caribbean and Cocos plates is concentrated along E-W dextral strike-slip faults parallel to the volcanic arc.

Innate immune genes including a mucin-like gene, mul-1, induced by ionizing radiation in Caenorhabditis elegans.

PubMed

Kimura, Takafumi; Takanami, Takako; Sakashita, Tetsuya; Wada, Seiichi; Kobayashi, Yasuhiko; Higashitani, Atsushi

2012-10-01

The effect of radiation on the intestine has been studied for more than one hundred years. It remains unclear, however, whether this organ uses specific defensive mechanisms against ionizing radiation. The infection with Pseudomonas aeruginosa (PA14) in Caenorhabditis elegans induces up-regulation of innate immune response genes. Here, we found that exposure to ionizing radiation also induces certain innate immune response genes such as F49F1.6 (termed mul-1), clec-4, clec-67, lys-1 and lys-2 in the intestine. Moreover, pre-treatment with ionizing radiation before seeding on PA14 lawn plate significantly increased survival rate in the nematode. We also studied transcription pathway of the mul-1 in response to ionizing radiation. Induction of mul-1 gene was highly dependent on the ELT-2 transcription factor and p38 MAPK. Moreover, the insulin/IGF-1 signal pathway works to enhance induction of this gene. The mul-1 gene showed a different induction pattern from the DNA damage response gene, ced-13, which implies that the expression of this gene might be triggered as an indirect effect of radiation. Silencing of the mul-1 gene led to growth retardation after treatment with ionizing radiation. We describe the cross-tolerance between the response to radiation exposure and the innate immune system.

Dynamic strain distribution of FRP plate under blast loading

NASA Astrophysics Data System (ADS)

Saburi, T.; Yoshida, M.; Kubota, S.

2017-02-01

The dynamic strain distribution of a fiber re-enforced plastic (FRP) plate under blast loading was investigated using a Digital Image Correlation (DIC) image analysis method. The testing FRP plates were mounted in parallel to each other on a steel frame. 50 g of composition C4 explosive was used as a blast loading source and set in the center of the FRP plates. The dynamic behavior of the FRP plate under blast loading were observed by two high-speed video cameras. The set of two high-speed video image sequences were used to analyze the FRP three-dimensional strain distribution by means of DIC method. A point strain profile extracted from the analyzed strain distribution data was compared with a directly observed strain profile using a strain gauge and it was shown that the strain profile under the blast loading by DIC method is quantitatively accurate.

Resonant Interaction of a Rectangular Jet with a Flat-Plate

NASA Technical Reports Server (NTRS)

Zaman, K. B. M. Q.; Fagan, A. F.; Clem, M. M.; Brown, C. A.

2014-01-01

A resonant interaction between a large aspect ratio rectangular jet and a flat-plate is addressed in this experimental study. The plate is placed parallel to but away from the direct path of the jet. At high subsonic conditions and for certain relative locations of the plate, the resonance accompanied by an audible tone is encountered. The trends of the tone frequency variation exhibit some similarities to, but also marked differences from, corresponding trends of the well-known edge-tone phenomenon. Under the resonant condition flow visualization indicates a periodic flapping motion of the jet column. Phase-averaged Mach number data obtained near the plate's trailing edge illustrate that the jet cross-section goes through large contortions within the period of the tone. Farther downstream a clear 'axis switching' takes place. These results suggest that the assumption of two-dimensionality should be viewed with caution in any analysis of the flow.

Melting heat transport of nanofluidic problem over a Riga plate with erratic thickness: Use of Keller Box scheme

NASA Astrophysics Data System (ADS)

Iqbal, Z.; Azhar, Ehtsham; Mehmood, Zaffar; Maraj, E. N.

Present article is a study of stagnation point flow over Riga plate with erratic thickness. Riga plate is an electromagnetic surface in which electrodes are assembled alternatively. This arrangement generates electromagnetic hydrodynamic behavior in the fluid flow. This is an attempt to investigate influence of melting heat, thermal radiation and viscous dissipation effects on Riga plate. A traversal electric and magnetic fields are produced by Riga plate. It causes Lorentz force parallel to wall which contributes in directing flow pattern. Physical problem is modeled and reduced nonlinear system is solved numerically. Comparative analysis is carried out between solutions obtained by Keller Box Method and shooting technique with Runge-Kutta Fehlberg method of order 5. It is noted that melting heat transfer reduces temperature distribution whereas radiation parameter upsurge it. Velocity is accelerated by modified Hartman number and Eckert number contributes in raising temperature.

AUTOMATIC COUNTER

DOEpatents

Robinson, H.P.

1960-06-01

An automatic counter of alpha particle tracks recorded by a sensitive emulsion of a photographic plate is described. The counter includes a source of mcdulated dark-field illumination for developing light flashes from the recorded particle tracks as the photographic plate is automatically scanned in narrow strips. Photoelectric means convert the light flashes to proportional current pulses for application to an electronic counting circuit. Photoelectric means are further provided for developing a phase reference signal from the photographic plate in such a manner that signals arising from particle tracks not parallel to the edge of the plate are out of phase with the reference signal. The counting circuit includes provision for rejecting the out-of-phase signals resulting from unoriented tracks as well as signals resulting from spurious marks on the plate such as scratches, dust or grain clumpings, etc. The output of the circuit is hence indicative only of the tracks that would be counted by a human operator.

Ground cross-modal impedance as a tool for analyzing ground/plate interaction and ground wave propagation.

PubMed

Grau, L; Laulagnet, B

2015-05-01

An analytical approach is investigated to model ground-plate interaction based on modal decomposition and the two-dimensional Fourier transform. A finite rectangular plate subjected to flexural vibration is coupled with the ground and modeled with the Kirchhoff hypothesis. A Navier equation represents the stratified ground, assumed infinite in the x- and y-directions and free at the top surface. To obtain an analytical solution, modal decomposition is applied to the structure and a Fourier Transform is applied to the ground. The result is a new tool for analyzing ground-plate interaction to resolve this problem: ground cross-modal impedance. It allows quantifying the added-stiffness, added-mass, and added-damping from the ground to the structure. Similarity with the parallel acoustic problem is highlighted. A comparison between the theory and the experiment shows good matching. Finally, specific cases are investigated, notably the influence of layer depth on plate vibration.

Field theoretic approach to roughness corrections

NASA Astrophysics Data System (ADS)

Wu, Hua Yao; Schaden, Martin

2012-02-01

We develop a systematic field theoretic description of roughness corrections to the Casimir free energy of a massless scalar field in the presence of parallel plates with mean separation a. Roughness is modeled by specifying a generating functional for correlation functions of the height profile. The two-point correlation function being characterized by its variance, σ2, and correlation length, ℓ. We obtain the partition function of a massless scalar quantum field interacting with the height profile of the surface via a δ-function potential. The partition function is given by a holographic reduction of this model to three coupled scalar fields on a two-dimensional plane. The original three-dimensional space with a flat parallel plate at a distance a from the rough plate is encoded in the nonlocal propagators of the surface fields on its boundary. Feynman rules for this equivalent 2+1-dimensional model are derived and its counterterms constructed. The two-loop contribution to the free energy of this model gives the leading roughness correction. The effective separation, aeff, to a rough plate is measured to a plane that is displaced a distance ρ∝σ2/ℓ from the mean of its profile. This definition of the separation eliminates corrections to the free energy of order 1/a4 and results in unitary scattering matrices. We obtain an effective low-energy model in the limit ℓ≪a. It determines the scattering matrix and equivalent planar scattering surface of a very rough plate in terms of the single length scale ρ. The Casimir force on a rough plate is found to always weaken with decreasing correlation length ℓ. The two-loop approximation to the free energy interpolates between the free energy of the effective low-energy model and that of the proximity force approximation - the force on a very rough plate with σ≳0.5ℓ being weaker than on a planar Dirichlet surface at any separation.

Three holes bound to a double acceptor - Be(+) in germanium

NASA Technical Reports Server (NTRS)

Haller, E. E.; Mcmurray, R. E., Jr.; Falicov, L. M.; Haegel, N. M.; Hansen, W. L.

1983-01-01

A double acceptor binding three holes has been observed for the first time with photoconductive far-infrared spectroscopy in beryllium-doped germanium single crystals. This new center, Be(+), has a hole binding energy of about 5 meV and is only present when free holes are generated by ionization of either neutral shallow acceptors or neutral Be double acceptors. The Be(+) center thermally ionizes above 4 K. It disappears at a uniaxial stress higher than about a billion dyn/sq cm parallel to (111) as a result of the lifting of the valence-band degeneracy.

Additive manufactured bipolar plate for high-efficiency hydrogen production in proton exchange membrane electrolyzer cells

DOE PAGES

Yang, Gaoqiang; Mo, Jingke; Kang, Zhenye; ...

2017-05-06

Additive manufacturing (AM) technology is capable of fast and low-cost prototyping from complex 3D digital models. To take advantage of this technology, a stainless steel (SS) plate with parallel flow field served as a combination of a cathode bipolar plate and a current distributor; it was fabricated using selective laser melting (SLM) techniques and investigated in a proton exchange membrane electrolyzer cell (PEMEC) in-situ for the first time. The experimental results show that the PEMEC with an AM SS cathode bipolar plate can achieve an excellent performance for hydrogen production for a voltage of 1.779 V and a current densitymore » of 2.0 A/cm 2. The AM SS cathode bipolar plate was also characterized by SEM and EDS, and the results show a uniform elemental distribution across the plate with very limited oxidization. As a result, this research demonstrates that AM method could be a route to aid cost-effective and rapid development of PEMECs.« less

Investigating the Feedback Path in a Jet-Surface Resonant Interaction

NASA Technical Reports Server (NTRS)

Zaman, K. B. M. Q.; Fagan, A. F.; Bridges, J. E.; Brown, C. A.

2015-01-01

A resonant interaction between an 8:1 aspect ratio rectangular jet and flat-plates, placed parallel to the jet, is studied experimentally. For certain locations of the plate relative to the jet, the resonance takes place with a loud accompanying tone. The sound pressure level spectra are often marked by multiple peaks. The frequencies of the spectral peaks are studied as a function of the streamwise length of the plate, its relative location to the jet as well as the jet Mach number. It is demonstrated that the tones are not due to a simple feedback between the plate's trailing edge and the nozzle's exit; the leading edge of the plate also comes into play in the frequency selection. With parametric variation, it is found that there is an order in the most energetic spectral peaks; their frequencies cluster in distinct bands. The 'fundamental', i.e., the lowest frequency band is explained by an acoustic feedback involving diffraction at the plate's leading edge.

Three point lead screw positioning apparatus for a cavity tuning plate

NASA Technical Reports Server (NTRS)

Calco, Frank S. (Inventor)

1993-01-01

Three lead screws are provided for adjusting the position of a traversing plate. Each of the three lead screws is threaded through a collar that is press fitted through the center of one of three pinion gears. A sun gear meshes with all three pinion gears and transversely moves the three lead screws upon actuation of a drive gear. The drive gear meshes with the sun gear and is driven by a handle or servomotor. When the handle or servomotor rotates the drive gear, the sun gear rotates causing the three pinion gears to rotate, thus, causing transverse movement of the three lead screws and, accordingly, transverse movement of the transversing plate. When the drive gear rotates, the traversing plate is driven in and out of a microwave cavity. Thus, the length or size of the cavity can be tuned while maintaining the traversing plate in an exact parallel relationship with an opposing plate on another end of the cavity.

Additive manufactured bipolar plate for high-efficiency hydrogen production in proton exchange membrane electrolyzer cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Gaoqiang; Mo, Jingke; Kang, Zhenye

Additive manufacturing (AM) technology is capable of fast and low-cost prototyping from complex 3D digital models. To take advantage of this technology, a stainless steel (SS) plate with parallel flow field served as a combination of a cathode bipolar plate and a current distributor; it was fabricated using selective laser melting (SLM) techniques and investigated in a proton exchange membrane electrolyzer cell (PEMEC) in-situ for the first time. The experimental results show that the PEMEC with an AM SS cathode bipolar plate can achieve an excellent performance for hydrogen production for a voltage of 1.779 V and a current densitymore » of 2.0 A/cm 2. The AM SS cathode bipolar plate was also characterized by SEM and EDS, and the results show a uniform elemental distribution across the plate with very limited oxidization. As a result, this research demonstrates that AM method could be a route to aid cost-effective and rapid development of PEMECs.« less

Three point lead screw positioning apparatus for a cavity tuning plate

NASA Astrophysics Data System (ADS)

Calco, Frank S.

1993-09-01

Three lead screws are provided for adjusting the position of a traversing plate. Each of the three lead screws is threaded through a collar that is press fitted through the center of one of three pinion gears. A sun gear meshes with all three pinion gears and transversely moves the three lead screws upon actuation of a drive gear. The drive gear meshes with the sun gear and is driven by a handle or servomotor. When the handle or servomotor rotates the drive gear, the sun gear rotates causing the three pinion gears to rotate, thus, causing transverse movement of the three lead screws and, accordingly, transverse movement of the transversing plate. When the drive gear rotates, the traversing plate is driven in and out of a microwave cavity. Thus, the length or size of the cavity can be tuned while maintaining the traversing plate in an exact parallel relationship with an opposing plate on another end of the cavity.

Lightweight bipolar storage battery

NASA Technical Reports Server (NTRS)

Rowlette, John J. (Inventor)

1992-01-01

An apparatus [10] is disclosed for a lightweight bipolar battery of the end-plate cell stack design. Current flow through a bipolar cell stack [12] is collected by a pair of copper end-plates [16a,16b] and transferred edgewise out of the battery by a pair of lightweight, low resistance copper terminals [28a,28b]. The copper terminals parallel the surface of a corresponding copper end-plate [16a,16b] to maximize battery throughput. The bipolar cell stack [12], copper end-plates [16a,16b] and copper terminals [28a,28b] are rigidly sandwiched between a pair of nonconductive rigid end-plates [20] having a lightweight fiber honeycomb core which eliminates distortion of individual plates within the bipolar cell stack due to internal pressures. Insulating foam [30] is injected into the fiber honeycomb core to reduce heat transfer into and out of the bipolar cell stack and to maintain uniform cell performance. A sealed battery enclosure [ 22] exposes a pair of terminal ends [26a,26b] for connection with an external circuit.

Shallow Mantle Anisotropy Beneath the Juan de Fuca Plate

NASA Astrophysics Data System (ADS)

VanderBeek, Brandon P.; Toomey, Douglas R.

2017-11-01

The anisotropic fabric of the oceanic mantle lithosphere is often assumed to parallel paleo-relative plate motion (RPM). However, we find evidence that this assumption is invalid beneath the Juan de Fuca (JdF) plate. Using travel times of seismic energy propagating through the topmost mantle, we find that the fast direction of P wave propagation is rotated 18° ± 3° counterclockwise to the paleo-spreading direction and strikes between Pacific-JdF relative and JdF absolute plate motion (APM). The mean mantle velocity is 7.85 ± 0.02 km/s with 4.6% ± 0.4% anisotropy. Synthesis of the plate-averaged Pn anisotropy signal with measurements of Pn anisotropy beneath the JdF Ridge and SKS splits across the JdF plate suggests that the anisotropic structure of the topmost mantle continues to evolve away from the spreading center to more closely align with APM. We infer that the oceanic mantle lithosphere may record the influence of both paleo-RPM and paleo-APM.

A new estimate for present-day Cocos-Caribbean Plate motion: Implications for slip along the Central American Volcanic Arc

NASA Astrophysics Data System (ADS)

DeMets, Charles

Velocities from 153 continuously-operating GPS sites on the Caribbean, North American, and Pacific plates are combined with 61 newly estimated Pacific-Cocos seafloor spreading rates and additional marine geophysical data to derive a new estimate of present-day Cocos-Caribbean plate motion. A comparison of the predicted Cocos-Caribbean direction to slip directions of numerous shallow-thrust subduction earthquakes from the Middle America trench between Costa Rica and Guatemala shows the slip directions to be deflected 10° clockwise from the plate convergence direction, supporting the hypothesis that frequent dextral strike-slip earthquakes along the Central American volcanic arc result from partitioning of oblique Cocos-Caribbean plate convergence. Linear velocity analysis for forearc locations in Nicaragua and Guatemala predicts 14±2 mm yr-1 of northwestward trench-parallel slip of the forearc relative to the Caribbean plate, possibly decreasing in magnitude in El Salvador and Guatemala, where extension east of the volcanic arc complicates the tectonic setting.

Influence of Ionization and Beam Quality on Interaction of TW-Peak CO2 Laser with Hydrogen Plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Samulyak, Roman

3D numerical simulations of the interaction of a powerful CO2 laser with hydrogen jets demonstrating the role of ionization and laser beam quality are presented. Simulations are performed in support of the plasma wakefield accelerator experiments being conducted at the BNL Accelerator Test Facility (ATF). The CO2 laser at BNL ATF has several potential advantages for laser wakefield acceleration compared to widely used solid-state lasers. SPACE, a parallel relativistic Particle-in-Cell code, developed at SBU and BNL, has been used in these studies. A novelty of the code is its set of efficient atomic physics algorithms that compute ionization and recombinationmore » rates on the grid and transfer them to particles. The primary goal of the initial BNL experiments was to characterize the plasma density by measuring the sidebands in the spectrum of the probe laser. Simulations, that resolve hydrogen ionization and laser spectra, help explain several trends that were observed in the experiments.« less

Studies of acoustic effects on a flow boundary layer in air

NASA Technical Reports Server (NTRS)

Mechel, F.; Schilz, W.

1986-01-01

Effects of sound fields on the flow boundary layer on a flat plate subjected to a parallel flow are studied. The boundary layer is influenced by controlling the stagnation point flow at the front edge of the plate. Depending on the Reynolds number and sound frequency, excitation or suppression of turbulent is observed. Measurements were taken at wind velocities between 10 and 30 m/sec and sound frequencies between 0.2 and 3.0 kHz.

Telescoping tube assembly

NASA Technical Reports Server (NTRS)

Sturm, Albert J. (Inventor); Marrinan, Thomas E. (Inventor)

1995-01-01

An extensible and retractable telescoping tube positions test devices that inspect large stationary objects. The tube has three dimensional adjustment capabilities and is vertically suspended from a frame. The tube sections are independently supported with each section comprising U-shaped housing secured to a thicker support plate. Guide mechanisms preferably mounted only to the thicker plates guide each tube section parallel to a reference axis with improved accuracy so that the position of the remote end of the telescoping tube is precisely known.

Multiple piezo-patch energy harvesters on a thin plate with respective AC-DC conversion

NASA Astrophysics Data System (ADS)

Aghakhani, Amirreza; Basdogan, Ipek

2018-03-01

Piezoelectric patch energy harvesters can be directly integrated to plate-like structures which are widely used in automotive, marine and aerospace applications, to convert vibrational energy to electrical energy. This paper presents two different AC-DC conversion techniques for multiple patch harvesters, namely single rectifier and respective rectifiers. The first case considers all the piezo-patches are connected in parallel to a single rectifier, whereas in the second case, each harvester is respectively rectified and then connected in parallel to a smoothing capacitor and a resistive load. The latter configuration of AC-DC conversion helps to avoid the electrical charge cancellation which is a problem with the multiple harvesters attached to different locations of the host plate surface. Equivalent circuit model of the multiple piezo-patch harvesters is developed in the SPICE software to simulate the electrical response. The system parameters are obtained from the modal analysis solution of the plate. Simulations of the voltage frequency response functions (FRFs) for the standard AC input - AC output case are conducted and validated by experimental data. Finally, for the AC input - DC output case, numerical simulation and experimental results of the power outputs of multiple piezo-patch harvesters with multiple AC-DC converters are obtained for a wide range of resistive loads and compared with the same array of harvesters connected to a single AC-DC converter.

Surface flatness measurement of quasi-parallel plates employing three-beam interference with strong reference beam

NASA Astrophysics Data System (ADS)

Sunderland, Zofia; Patorski, Krzysztof

2016-12-01

A big challenge for standard interferogram analysis methods such as Temporal Phase Shifting or Fourier Transform is a parasitic set of fringes which might occur in the analyzed fringe pattern intensity distribution. It is encountered, for example, when transparent glass plates with quasi-parallel surfaces are tested in Fizeau or Twyman-Green interferometers. Besides the beams reflected from the plate front surface and the interferometer reference the beam reflected from the plate rear surface also plays important role; its amplitude is comparable with the amplitude of other beams. In result we face three families of fringes of high contrast which cannot be easily separated. Earlier we proposed a competitive solution for flatness measurements which relies on eliminating one of those fringe sets from the three-beam interferogram and separating two remaining ones with the use of 2D Continuous Wavelet Transform. In this work we cover the case when the intensity of the reference beam is significantly higher than the intensities of two object beams. The main advantage of differentiating beam intensities is the change in contrast of individual fringe families. Processing of such three-beam interferograms is modified but also takes advantage of 2D CWT. We show how to implement this method in Twyman-Green and Fizeau setups and compare this processing path and measurement procedures with previously proposed solutions.

Flow of nanofluid past a Riga plate

NASA Astrophysics Data System (ADS)

Ahmad, Adeel; Asghar, Saleem; Afzal, Sumaira

2016-03-01

This paper studies the mixed convection boundary layer flow of a nanofluid past a vertical Riga plate in the presence of strong suction. The mathematical model incorporates the Brownian motion and thermophoresis effects due to nanofluid and the Grinberg-term for the wall parallel Lorentz force due to Riga plate. The analytical solution of the problem is presented using the perturbation method for small Brownian and thermophoresis diffusion parameters. The numerical solution is also presented to ensure the reliability of the asymptotic method. The comparison of the two solutions shows an excellent agreement. The correlation expressions for skin friction, Nusselt number and Sherwood number are developed by performing linear regression on the obtained numerical data. The effects of nanofluid and the Lorentz force due to Riga plate, on the skin friction are discussed.

Electrochemical cell has internal resistive heater element

NASA Technical Reports Server (NTRS)

Colston, E. F.; Ford, F. E.; Hennigan, T. J.

1968-01-01

External source supplies power to electrochemical cells containing internal resistive heater element. Each cell plate is individually contained in its own Pellon bag, enabling the heater element to be arranged in a continuous, parallel circuit.

Topographic relationship between root apex of mesially and horizontally impacted mandibular third molar and lingual plate: cross-sectional analysis using CBCT

PubMed Central

Wang, Dongmiao; He, Xiaotong; Wang, Yanling; Zhou, Guangchao; Sun, Chao; Yang, Lianfeng; Bai, Jianling; Gao, Jun; Wu, Yunong; Cheng, Jie

2016-01-01

The present study was aimed to determine the topographic relationship between root apex of the mesially and horizontally impacted mandibular third molar and lingual plate of mandible. The original cone beam computed tomography (CBCT) data of 364 teeth from 223 patients were retrospectively collected and analyzed. The topographic relationship between root apex and lingual plate on cross-sectional CBCT images was classified as non-contact (99), contact (145) and perforation (120). The cross-sectional morphology of lingual plate at the level of root apex was defined as parallel (28), undercut (38), slanted (29) and round (4). The distribution of topographic relationship between root apex and lingual plate significantly associated with gender, impaction depth, root number and lingual plate morphology. Moreover, the average bone thickness of lingual cortex and distance between root apex and the outer surface of lingual plate were 1.02 and 1.39 mm, respectively. Furthermore, multivariate regression analyses identified impaction depth and lingual plate morphology as the risk factors for the contact and perforation subtypes between root apex and lingual plate. Collectively, our findings reveal the topographic proximity of root apex of impacted mandibular third molar to the lingual plate, which might be associated with intraoperative and postoperative complications during tooth extraction. PMID:27991572

Conception through build of an automated liquids processing system for compound management in a low-humidity environment.

PubMed

Belval, Richard; Alamir, Ab; Corte, Christopher; DiValentino, Justin; Fernandes, James; Frerking, Stuart; Jenkins, Derek; Rogers, George; Sanville-Ross, Mary; Sledziona, Cindy; Taylor, Paul

2012-12-01

Boehringer Ingelheim's Automated Liquids Processing System (ALPS) in Ridgefield, Connecticut, was built to accommodate all compound solution-based operations following dissolution in neat DMSO. Process analysis resulted in the design of two nearly identical conveyor-based subsystems, each capable of executing 1400 × 384-well plate or punch tube replicates per batch. Two parallel-positioned subsystems are capable of independent execution or alternatively executed as a unified system for more complex or higher throughput processes. Primary ALPS functions include creation of high-throughput screening plates, concentration-response plates, and reformatted master stock plates (e.g., 384-well plates from 96-well plates). Integrated operations included centrifugation, unsealing/piercing, broadcast diluent addition, barcode print/application, compound transfer/mix via disposable pipette tips, and plate sealing. ALPS key features included instrument pooling for increased capacity or fail-over situations, programming constructs to associate one source plate to an array of replicate plates, and stacked collation of completed plates. Due to the hygroscopic nature of DMSO, ALPS was designed to operate within a 10% relativity humidity environment. The activities described are the collaborative efforts that contributed to the specification, build, delivery, and acceptance testing between Boehringer Ingelheim Pharmaceuticals, Inc. and the automation integration vendor, Thermo Scientific Laboratory Automation (Burlington, ON, Canada).

Size and Charge Dependence of Ion Transport in Human Nail Plate

PubMed Central

Baswan, Sudhir M.; Li, S. Kevin; LaCount, Terri D.; Kasting, Gerald B.

2016-01-01

The electrical properties of human nail plate are poorly characterized, yet are a key determinate of the potential to treat nail diseases such as onychomycosis using iontophoresis. In order to address this deficiency, molar conductivities of 17 electrolytes comprising 12 ionic species were determined in hydrated human nail plate in vitro. Cation transport numbers across the nail for 11 of these electrolytes were determined by the electromotive force method. Effective ionic mobilities and diffusivities at infinite dilution for all ionic species were determined by regression analysis. The ratios of diffusivities in nail to those in solution were found to correlate inversely with the hydrodynamic radii of the ions according to a power law relationship having an exponent of −1.75 ± 0.27, a substantially steeper size dependence than observed for similar experiments in skin. Effective diffusivities of cations in nail were three-fold higher than those of comparably sized anions. These results reflect the strong size and charge selectivity of the nail plate for ionic conduction and diffusion. The analysis implies that efficient transungual iontophoretic delivery of ionized drugs having radii upwards of 5 Å (approximately MW ≥ 340 Da) will require chemical or mechanical alteration of the nail plate. PMID:26886342

Constant-Distance Mode Nanospray Desorption Electrospray Ionization Mass Spectrometry Imaging of Biological Samples with Complex Topography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nguyen, Son N.; Liyu, Andrey V.; Chu, Rosalie K.

A new approach for constant distance mode mass spectrometry imaging of biological samples using nanospray desorption electrospray ionization (nano-DESI MSI) was developed by integrating a shear-force probe with nano-DESI probe. The technical concept and basic instrumental setup as well as general operation of the system are described. Mechanical dampening of resonant oscillations due to the presence of shear forces between the probe and the sample surface enables constant-distance imaging mode via a computer controlled closed feedback loop. The capability of simultaneous chemical and topographic imaging of complex biological samples is demonstrated using living Bacillus Subtilis ATCC 49760 colonies on agarmore » plates. The constant-distance mode nano-DESI MSI enabled imaging of many metabolites including non-ribosomal peptides (surfactin, plipastatin and iturin) and iron-bound heme on the surface of living bacterial colonies ranging in diameter from 10 mm to 13 mm with height variations of up to 0.8 mm above the agar plate. Co-registration of ion images to topographic images provided higher-contrast images. Constant-mode nano-DESI MSI is ideally suited for imaging biological samples of complex topography in their native state.« less

Semi-automated 96-well solid-phase extraction and gas chromatography-negative chemical ionization tandem mass spectrometry for the trace analysis of fluprostenol in rat plasma.

PubMed

Gauw, R D; Stoffolano, P J; Kuhlenbeck, D L; Patel, V S; Garver, S M; Baker, T R; Wehmeyer, K R

2000-07-21

Semi-automated 96-well plate solid-phase extraction (SPE) was used for sample preparation of fluprostenol, a prostaglandin analog, in rat plasma prior to detection by gas chromatography-negative chemical ionization tandem mass spectrometry (GC-NCI-MS-MS). A liquid handling system was utilized for all aspects of sample handling prior to SPE including transferring of samples into a 96-well format, preparation of standards as well as addition of internal standard to standards, quality control samples and study samples. SPE was performed in a 96-well plate format using octadecylsilane packing and the effluent from the SPE was dried in a custom-made 96-well apparatus. The sample residue was derivatized sequentially with pentafluorobenzylbromide followed by N-methyl-N-trimethylsilyltrifluoroacetamide. The derivatized sample was then analyzed using GC-NCI-MS-MS. The dynamic range for the method was from 7 to 5800 pg/ml with a 0.1-ml plasma sample. The methodology was evaluated over a 4-day period and demonstrated an accuracy of 90-106% with a precision of 2.4-12.9%.

Martian Atmospheric Pressure Static Charge Elimination Tool

NASA Technical Reports Server (NTRS)

Johansen, Michael R.

2014-01-01

A Martian pressure static charge elimination tool is currently in development in the Electrostatics and Surface Physics Laboratory (ESPL) at NASA's Kennedy Space Center. In standard Earth atmosphere conditions, static charge can be neutralized from an insulating surface using air ionizers. These air ionizers generate ions through corona breakdown. The Martian atmosphere is 7 Torr of mostly carbon dioxide, which makes it inherently difficult to use similar methods as those used for standard atmosphere static elimination tools. An initial prototype has been developed to show feasibility of static charge elimination at low pressure, using corona discharge. A needle point and thin wire loop are used as the corona generating electrodes. A photo of the test apparatus is shown below. Positive and negative high voltage pulses are sent to the needle point. This creates positive and negative ions that can be used for static charge neutralization. In a preliminary test, a floating metal plate was charged to approximately 600 volts under Martian atmospheric conditions. The static elimination tool was enabled and the voltage on the metal plate dropped rapidly to -100 volts. This test data is displayed below. Optimization is necessary to improve the electrostatic balance of the static elimination tool.

Residual Agar Determination in Bacterial Spores by Electrospray Ionization Mass Spectrometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wahl, Karen L.; Colburn, Heather A.; Wunschel, David S.

2010-02-15

Presented here is an analytical method to detect residual agar from a bacterial spore sample as an indication of culturing on an agar plate. This method is based on the resolubilization of agar polysaccharide from a bacterial spore sample, enzymatic digestion, followed by electrospray ionization tandem mass spectrometry (ESI-MSn) analysis for detection of a specific agar fragment ion. A range of Bacillus species and strains were selected to demonstrate the effectiveness of this approach. The characteristic agar fragment ion was detected in the spores grown on agar that were washed from 1 to 5 times, irradiated or non-irradiated and notmore » in the spores grown in broth. A sample containing approximately 108 spores is currently needed for confident detection of residual agar from culture on agar plates in the presence of bacterial spores with a limit of detection of approximately 1 ppm agar spiked into a broth-grown spore sample. The results of a proficiency test with 42 blinded samples are presented demonstrating the utility of this method with no false positives and only 3 false negatives for samples that were below the detection level of the method as documented.« less

NOTE: Calibration of low-energy electron beams from a mobile linear accelerator with plane-parallel chambers using both TG-51 and TG-21 protocols

NASA Astrophysics Data System (ADS)

Beddar, A. S.; Tailor, R. C.

2004-04-01

A new approach to intraoperative radiation therapy led to the development of mobile linear electron accelerators that provide lower electron energy beams than the usual conventional accelerators commonly encountered in radiotherapy. Such mobile electron accelerators produce electron beams that have nominal energies of 4, 6, 9 and 12 MeV. This work compares the absorbed dose output calibrations using both the AAPM TG-51 and TG-21 dose calibration protocols for two types of ion chambers: a plane-parallel (PP) ionization chamber and a cylindrical ionization chamber. Our results indicate that the use of a 'Markus' PP chamber causes 2 3% overestimation in dose output determination if accredited dosimetry-calibration laboratory based chamber factors \\big(N_{{\\rm D},{\\rm w}}^{{}^{60}{\\rm Co}}, N_x\\big) are used. However, if the ionization chamber factors are derived using a cross-comparison at a high-energy electron beam, then a good agreement is obtained (within 1%) with a calibrated cylindrical chamber over the entire energy range down to 4 MeV. Furthermore, even though the TG-51 does not recommend using cylindrical chambers at the low energies, our results show that the cylindrical chamber has a good agreement with the PP chamber not only at 6 MeV but also down to 4 MeV electron beams.

Plasma q -plate for generation and manipulation of intense optical vortices

NASA Astrophysics Data System (ADS)

Qu, Kenan; Jia, Qing; Fisch, Nathaniel J.

2017-11-01

An optical vortex is a light wave with a twisting wavefront around its propagation axis and null intensity in the beam center. Its unique spatial structure of field lends itself to a broad range of applications, including optical communication, quantum information, superresolution microscopy, and multidimensional manipulation of particles. However, accessible intensity of optical vortices have been limited to material ionization threshold. This limitation might be removed by using the plasma medium. Here we propose the design of suitably magnetized plasmas which, functioning as a q -plate, leads to a direct conversion from a high-intensity Gaussian beam into a twisted beam. A circularly polarized laser beam in the plasma accumulates an azimuthal-angle-dependent phase shift and hence forms a twisting wavefront. Our three-dimensional particle-in-cell simulations demonstrate extremely high-power conversion efficiency. The plasma q -plate can work in a large range of frequencies spanning from terahertz to the optical domain.

Discharge dynamics of pin-to-plate dielectric barrier discharge at atmospheric pressure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun Liqun; Huang, Xiaojiang; Member of Magnetic Confinement Fusion Research Center, Ministry of Education of the People's Republic of China, Shanghai 201620

2010-11-15

The discharge dynamics of pin-to-plate dielectric barrier discharge was studied in atmospheric helium at 20 kHz. The discharge was predominately ignited in positive half cycle of applied voltage with sinusoidal waveform. The temporal evolution of the discharge was investigated vertically along the discharge gap and radically on the dielectric surface by time resolved imaging. It is found that a discharge column with a diameter of 2 mm was ignited above the pin electrode and expanded toward a plate electrode. On the dielectric surface with space charge accumulation, plasma disk in terms of plasma ring was formed with radius up tomore » 25 mm. The expansion velocity of plasma ring can reach a hypersonic speed of 3.0 km/s. The ionization wave due to electron diffusion is considered to be the mechanism for plasma ring formation and dynamics.« less

Discharge dynamics of pin-to-plate dielectric barrier discharge at atmospheric pressure

NASA Astrophysics Data System (ADS)

Sun, Liqun; Huang, Xiaojiang; Zhang, Jie; Zhang, Jing; Shi, J. J.

2010-11-01

The discharge dynamics of pin-to-plate dielectric barrier discharge was studied in atmospheric helium at 20 kHz. The discharge was predominately ignited in positive half cycle of applied voltage with sinusoidal waveform. The temporal evolution of the discharge was investigated vertically along the discharge gap and radically on the dielectric surface by time resolved imaging. It is found that a discharge column with a diameter of 2 mm was ignited above the pin electrode and expanded toward a plate electrode. On the dielectric surface with space charge accumulation, plasma disk in terms of plasma ring was formed with radius up to 25 mm. The expansion velocity of plasma ring can reach a hypersonic speed of 3.0 km/s. The ionization wave due to electron diffusion is considered to be the mechanism for plasma ring formation and dynamics.

DEVELOPMENT OF A CHARGING/COLLECTING DEVICE FOR HIGH RESISTIVITY DUST USING COOLED ELECTRODES

EPA Science Inventory

The paper discusses a charging/collecting device for high-resistivity fly ash, developed to control back-ionization by cooling the collector electrode internally with water. The device consists of parallel 6.0 cm pipes with corona wires suspended between them. The pipes provide a...

Artificial dielectric polarizing-beamsplitter and isolator for the terahertz region.

PubMed

Mendis, Rajind; Nagai, Masaya; Zhang, Wei; Mittleman, Daniel M

2017-07-19

We demonstrate a simple and effective strategy for implementing a polarizing beamsplitter for the terahertz spectral region, based on an artificial dielectric medium that is scalable to a range of desired frequencies. The artificial dielectric medium consists of a uniformly spaced stack of metal plates, which is electromagnetically equivalent to a stacked array of parallel-plate waveguides. The operation of the device relies on both the lowest-order, transverse-electric and transverse-magnetic modes of the parallel-plate waveguide. This is in contrast to previous work that relied solely on the transverse-electric mode. The fabricated polarizing beamsplitter exhibits extinction ratios as high as 42 dB along with insertion losses as low as 0.18 dB. Building on the same idea, we also demonstrate an isolator with non-reciprocal transmission, providing high isolation and low insertion loss at a select design frequency. The performance of our isolator far exceeds that of other experimentally demonstrated terahertz isolators, and indeed, even rivals that of commercially available isolators for optical wavelengths. Because these waveguide-based artificial dielectrics are low loss, inexpensive, and easy to fabricate, this approach offers a promising new route for polarization control of free-space terahertz beams.

Study on Properties of CoNi Films with mn Doping Prepared by Magnetic Fields Induced Codeposition Technology

NASA Astrophysics Data System (ADS)

Gang, Liang; Yu, Yundan; Ge, Hongliang; Wei, Guoying; Jiang, Li; Sun, Lixia

Magnetic field parallel to electric field was induced during plating process to prepare CoNiMn alloy films on copper substrate. Electrochemistry mechanism and properties of CoNiMn alloy films were investigated in this paper. Micro magnetohydrodynamic convection phenomenon caused by vertical component of current density and parallel magnetic field due to deformation of current distribution contributed directly to the improvement of cathode current and deposition rate. Cathode current of the CoNiMn plating system increased about 30% with 1T magnetic field induced. It was found that CoNiMn films electrodeposited with magnetic fields basically belonged to a kind of progressive nucleation mode. Higher magnetic intensity intended to obtain CoNiMn films with good crystal structures and highly preferred orientations. With the increase of magnetic intensities, surface morphology of CoNiMn alloy films changed from typically nodular to needle-like structures. Compared with coatings electrodeposited without magnetic field, CoNiMn alloy films prepared with magnetic fields possessed better magnetic properties. Coercivity, remanence and saturation magnetization of samples increased sharply when 1T magnetic field was induced during plating process.

Solar flare model atmospheres

NASA Technical Reports Server (NTRS)

Hawley, Suzanne L.; Fisher, George H.

1993-01-01

Solar flare model atmospheres computed under the assumption of energetic equilibrium in the chromosphere are presented. The models use a static, one-dimensional plane parallel geometry and are designed within a physically self-consistent coronal loop. Assumed flare heating mechanisms include collisions from a flux of non-thermal electrons and x-ray heating of the chromosphere by the corona. The heating by energetic electrons accounts explicitly for variations of the ionized fraction with depth in the atmosphere. X-ray heating of the chromosphere by the corona incorporates a flare loop geometry by approximating distant portions of the loop with a series of point sources, while treating the loop leg closest to the chromospheric footpoint in the plane-parallel approximation. Coronal flare heating leads to increased heat conduction, chromospheric evaporation and subsequent changes in coronal pressure; these effects are included self-consistently in the models. Cooling in the chromosphere is computed in detail for the important optically thick HI, CaII and MgII transitions using the non-LTE prescription in the program MULTI. Hydrogen ionization rates from x-ray photo-ionization and collisional ionization by non-thermal electrons are included explicitly in the rate equations. The models are computed in the 'impulsive' and 'equilibrium' limits, and in a set of intermediate 'evolving' states. The impulsive atmospheres have the density distribution frozen in pre-flare configuration, while the equilibrium models assume the entire atmosphere is in hydrostatic and energetic equilibrium. The evolving atmospheres represent intermediate stages where hydrostatic equilibrium has been established in the chromosphere and corona, but the corona is not yet in energetic equilibrium with the flare heating source. Thus, for example, chromospheric evaporation is still in the process of occurring.

Development of a Radar-Frequency Metamaterial Measurement and Characterization Apparatus

DTIC Science & Technology

2012-03-01

Patterson Air Force Base, Ohio APPROVED FOR PUBLIC RELEASE; DISTRIBUTION IS UNLIMITED. The views expressed...17 GTRI Focused Beam System ................................................................................... 22 Shelby Parallel-Plate Waveguide...System ......................................................... 23 Figure 4: CST Model of Shelby PPWG

Oscillatory electroosmotic flow in a parallel-plate microchannel under asymmetric zeta potentials

NASA Astrophysics Data System (ADS)

Peralta, M.; Arcos, J.; Méndez, F.; Bautista, O.

2017-06-01

In this work, we conduct a theoretical analysis of the start-up of an oscillatory electroosmotic flow (EOF) in a parallel-plate microchannel under asymmetric zeta potentials. It is found that the transient evolution of the flow field is controlled by the parameters {R}ω , {R}\\zeta , and \\bar{κ }, which represent the dimensionless frequency, the ratio of the zeta potentials of the microchannel walls, and the electrokinetic parameter, which is defined as the ratio of the microchannel height to the Debye length. The analysis is performed for both low and high zeta potentials; in the former case, an analytical solution is derived, whereas in the latter, a numerical solution is obtained. These solutions provide the fundamental characteristics of the oscillatory EOFs for which, with suitable adjustment of the zeta potential and the dimensionless frequency, the velocity profiles of the fluid flow exhibit symmetric or asymmetric shapes.

Wetting of silicone oil onto a cell-seeded substrate

NASA Astrophysics Data System (ADS)

Lu, Yongjie; Chan, Yau Kei; Chao, Youchuang; Shum, Ho Cheung

2017-11-01

Wetting behavior of solid substrates in three-phase systems containing two immiscible liquids are widely studied. There exist many three-phase systems in biological environments, such as droplet-based microfluidics or tamponade of silicone oil for eye surgery. However, few studies focus on wetting behavior of biological surfaces with cells. Here we investigate wetting of silicone oil onto cell-seeded PMMA sheet immersed in water. Using a simple parallel-plate cell, we show the effect of cell density, viscosity of silicone oil, morphology of silicone oil drops and interfacial tension on the wetting phenomenon. The dynamics of wetting is also observed by squeezing silicone oil drop using two parallel plates. Experimental results are explained based on disjoining pressure which is dependent on the interaction of biological surfaces and liquid used. These findings are useful for explaining emulsification of silicone oil in ophthalmological applications.

Thermophoretic augmentation of particle deposition in natural convection flow through a parallel plate channel

NASA Astrophysics Data System (ADS)

Dinesh, K. K.; Jayaraj, S.

2008-10-01

Present paper deals with temperature driven mass deposition rate of particles known as thermophoretic wall flux when a hot flue gas in natural convection flow through a cooled isothermal vertical parallel plate channel. Present study finds application in particle filters used to trap soot particles from post combustion gases issuing out of small furnaces with low technical implications. Governing equations are solved using finite difference marching technique with channel inlet values as initial values. Channel heights required to regain hydrostatic pressure at the exit are estimated for various entry velocities. Effect of temperature ratio between wall and gas on thermophoretic wall flux is analysed and wall flux found to increase with decrease in temperature ratio. Results are compared with published works wherever possible and can be used to predict particle deposition rate as well as the conditions favourable for maximum particle deposition rate.

Multiturn split-conductor transmission-line resonator

NASA Astrophysics Data System (ADS)

Haziza, Nathalie; Bittoun, Jacques; Kan, Siew

1997-05-01

A split-conductor parallel-plate transmission line resonator is a simple structure made from bending a strip of double-face copper-clad printed-circuit board into a loop with alternate electrical discontinuities (gaps) on opposite sides. Its natural resonant frequency (Fn) is determined by the transmission line characteristic impedance, the loop diameter or strip length, and the number (Ng) of gaps. It is easy to design high frequency resonators simply by increasing Ng. We propose here a single-gap multiturn resonator for low frequency operation as well as a simplified expression for the determination of Fn. A design procedure of this type of resonator is outlined and illustrative examples with parallel-plate as well as ordinary 50 Ω coaxial transmission lines are given. Also, for a given cable length, numerical calculation shows that the minimum resonator frequency can be attained with a form factor of the order of 2.

THz wavefront manipulation based on metal waveguides

NASA Astrophysics Data System (ADS)

Wu, Mengru; Lang, Tingting; Shen, Changyu; Shi, Guohua; Han, Zhanghua

2018-07-01

In this paper, two waveguiding structures for arbitrary wavefront manipulation in the terahertz spectral region were proposed, designed and characterized. The first structure consists of parallel stack copper plates forming an array of parallel-plate waveguides (PPWGs). The second structure is three-dimensional metal rectangular waveguides array. The phase delay of the input wave after passing through the waveguide array is mainly determined by the effective index of the waveguides. Therefore, the waveguide array can be engineered using different core width distribution to generate any desired light beam. Examples, working at the frequency of 0.3 THz show that good focusing phenomenon with different focus lengths and spot sizes were observed, as well as arbitrarily tilted propagation of incident plane waves. The structure introduces a new method to perform wavefront manipulation, and can be utilized in many important applications in terahertz imaging and communication systems.

Large-deflection theory for end compression of long rectangular plates rigidly clamped along two edges

NASA Technical Reports Server (NTRS)

Levy, Samuel; Krupen, Philip

1943-01-01

The von Karman equations for flat plates are solved beyond the buckling load up to edge strains equal to eight time the buckling strain, for the extreme case of rigid clamping along the edges parallel to the load. Deflections, bending stresses, and membrane stresses are given as a function of end compressive load. The theoretical values of effective width are compared with the values derived for simple support along the edges parallel to the load. The increases in effective width due to rigid clamping drops from about 20 percent near the buckling strain to about 8 percent at an edge strain equal to eight times the buckling strain. Experimental values of effective width in the elastic range reported in NACA Technical Note No. 684 are between the theoretical curves for the extremes of simple support and rigid clamping.

Radiant Heat Transfer Between Nongray Parallel Plates of Tungsten

NASA Technical Reports Server (NTRS)

Branstetter, J. Robert

1961-01-01

Net radiant heat flow between two infinite, parallel, tungsten plates was computed by summing the monochromatic energy exchange; the results are graphically presented as a function of the temperatures of the two surfaces. In general these fluxes range from approximately a to 25 percent greater than the results of gray-body computations based on the same emissivity data. The selection of spectral emissivity data and the computational procedure are discussed. The present analytical procedure is so arranged that, as spectral emissivity data for a material become available, these data can be readily introduced into the NASA data-reduction equipment, which has been programmed to compute the net heat flux for the particular geometry and basic assumptions cited in the text. Nongray-body computational techniques for determining radiant heat flux appear practical provided the combination of select spectral emissivity data and the proper mechanized data-reduction equipment are brought to bear on the problem.

Parametric electroconvection in a weakly conducting fluid in a horizontal parallel-plate capacitor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kartavykh, N. N.; Smorodin, B. L., E-mail: bsmorodin@yandex.ru; Il’in, V. A.

2015-07-15

We study the flows of a nonuniformly heated weakly conducting fluid in an ac electric field of a horizontal parallel-plate capacitor. Analysis is carried out for fluids in which the charge formation is governed by electroconductive mechanism associated with the temperature dependence of the electrical conductivity of the medium. Periodic and chaotic regimes of fluid flow are investigated in the limiting case of instantaneous charge relaxation and for a finite relaxation time. Bifurcation diagrams and electroconvective regimes charts are constructed. The regions where fluid oscillations synchronize with the frequency of the external field are determined. Hysteretic transitions between electroconvection regimesmore » are studied. The scenarios of transition to chaotic oscillations are analyzed. Depending on the natural frequency of electroconvective system and the external field frequency, the transition from periodic to chaotic oscillations can occur via quasiperiodicity, a subharmonic cascade, or intermittence.« less

Parallel-plate wet denuder coupled ion chromatograph for near-real-time detection of trace acidic gases in clean room air.

PubMed

Takeuchi, Masaki; Tsunoda, Hiromichi; Tanaka, Hideji; Shiramizu, Yoshimi

2011-01-01

This paper describes the performance of our automated acidic (CH(3)COOH, HCOOH, HCl, HNO(2), SO(2), and HNO(3)) gases monitor utilizing a parallel-plate wet denuder (PPWD). The PPWD quantitatively collects gaseous contaminants at a high sample flow rate (∼8 dm(3) min(-1)) compared to the conventional methods used in a clean room. Rapid response to any variability in the sample concentration enables near-real-time monitoring. In the developed monitor, the analyte collected with the PPWD is pumped into one of two preconcentration columns for 15 min, and determined by means of ion chromatography. While one preconcentration column is used for chromatographic separation, the other is used for loading the sample solution. The system allows continuous monitoring of the common acidic gases in an advanced semiconductor manufacturing clean room. 2011 © The Japan Society for Analytical Chemistry

Symmetric Absorber-Coupled Far-Infrared Microwave Kinetic Inductance Detector

NASA Technical Reports Server (NTRS)

U-yen, Kongpop (Inventor); Wollack, Edward J. (Inventor); Brown, Ari D. (Inventor); Stevenson, Thomas R. (Inventor); Patel, Amil A. (Inventor)

2016-01-01

The present invention relates to a symmetric absorber-coupled far-infrared microwave kinetic inductance detector including: a membrane having an absorber disposed thereon in a symmetric cross bar pattern; and a microstrip including a plurality of conductor microstrip lines disposed along all edges of the membrane, and separated from a ground plane by the membrane. The conducting microstrip lines are made from niobium, and the pattern is made from a superconducting material with a transition temperature below niobium, including one of aluminum, titanium nitride, or molybdenum nitride. The pattern is disposed on both a top and a bottom of the membrane, and creates a parallel-plate coupled transmission line on the membrane that acts as a half-wavelength resonator at readout frequencies. The parallel-plate coupled transmission line and the conductor microstrip lines form a stepped impedance resonator. The pattern provides identical power absorption for both horizontal and vertical polarization signals.

Measurement of the Microwave Refractive Index of Materials Based on Parallel Plate Waveguides

NASA Astrophysics Data System (ADS)

Zhao, F.; Pei, J.; Kan, J. S.; Zhao, Q.

2017-12-01

An electrical field scanning apparatus based on a parallel plate waveguide method is constructed, which collects the amplitude and phase matrices as a function of the relative position. On the basis of such data, a method for calculating the refractive index of the measured wedge samples is proposed in this paper. The measurement and calculation results of different PTFE samples reveal that the refractive index measured by the apparatus is substantially consistent with the refractive index inferred with the permittivity of the sample. The proposed refractive index calculation method proposed in this paper is a competitive method for the characterization of the refractive index of materials with positive refractive index. Since the apparatus and method can be used to measure and calculate arbitrary direction of the microwave propagation, it is believed that both of them can be applied to the negative refractive index materials, such as metamaterials or “left-handed” materials.

Pulsed ultrasonic stir welding method

NASA Technical Reports Server (NTRS)

Ding, R. Jeffrey (Inventor)

2013-01-01

A method of performing ultrasonic stir welding uses a welding head assembly to include a plate and a rod passing through the plate. The rod is rotatable about a longitudinal axis thereof. In the method, the rod is rotated about its longitudinal axis during a welding operation. During the welding operation, a series of on-off ultrasonic pulses are applied to the rod such that they propagate parallel to the rod's longitudinal axis. At least a pulse rate associated with the on-off ultrasonic pulses is controlled.

Casimir force in the Gödel space-time and its possible induced cosmological inhomogeneity

NASA Astrophysics Data System (ADS)

Khodabakhshi, Sh.; Shojai, A.

2017-07-01

The Casimir force between two parallel plates in the Gödel universe is computed for a scalar field at finite temperature. It is observed that when the plates' separation is comparable with the scale given by the rotation of the space-time, the force becomes repulsive and then approaches zero. Since it has been shown previously that the universe may experience a Gödel phase for a small period of time, the induced inhomogeneities from the Casimir force are also studied.

Multichannel microscale system for high throughput preparative separation with comprehensive collection and analysis

DOEpatents

Karger, Barry L.; Kotler, Lev; Foret, Frantisek; Minarik, Marek; Kleparnik, Karel

2003-12-09

A modular multiple lane or capillary electrophoresis (chromatography) system that permits automated parallel separation and comprehensive collection of all fractions from samples in all lanes or columns, with the option of further on-line automated sample fraction analysis, is disclosed. Preferably, fractions are collected in a multi-well fraction collection unit, or plate (40). The multi-well collection plate (40) is preferably made of a solvent permeable gel, most preferably a hydrophilic, polymeric gel such as agarose or cross-linked polyacrylamide.

Velocity Distribution in the Boundary Layer of a Submerged Plate

NASA Technical Reports Server (NTRS)

Hansen, M

1930-01-01

This report deals with the measurement of the velocity distribution of the air in the velocity of a plate placed parallel to the air flow. The measurements took place in a small wind tunnel where the diameter of the entrance cone is 30 cm and the length of the free jet between the entrance and exit cones is about 2.5 m. The measurements were made in the free jet where the static pressure was constant, which was essential for the method of measurement used.

[The use of palisade technique in tympanoplasties after Heermann].

PubMed

Wielgosz, Romuald; Mroczkowski, Edward

2006-01-01

The palisade tympanoplasties-technique with using of tragal and conchal autografts for reconstruction of the tympanic membrane and the auditory canal wall was described. The operation started with the endaural incision. Tragal and conchal autograft palisade fragments with perichondrium for reconstruction of the tympanic membrane and the auditory canal wall have been used up to 1996 in 15,300 cases. We placed palisaded cartilage fragments parallel to the manubrium of the malleus in type I tympanoplasties and in type II or III procedures parallel to the long process of the incus. The "tunnel plasty" in the eustachian tubal entrance is performed with "simmering", "architrave" and "anti-architrave" to keep the tubal entrance open. This "tunnel plasty" results in a nice reconstruction of the tympano-meatal niche. The "annulus-stapes plate" in type III tympanoplasties replaces the function of the incus, crossing the promontory and reducing adhesions. This annulus-stapes bridge is fixed with a further palisade cartilage, "step plasty", which connects the "tunnel-plasty" with "annulus-stapes plate". The palisade-epitympanum-antrum plasty allows ventilation of the antrum via a tunnel constructed of well-fitting parallel pieces of cartilage fixed by self-tension (no glue) and replacing the bony canal wall. The "columella-tunnel plasty" has an L-shaped notch in the "annulus-stapes plate" fixing a columella of cartilage, placed in the oval window. Only in a case with a narrow oval window niche, a type IV palisade plasty can be performed or a prosthesis placed. The "annulus-stapes cartilage plate" is more stable reconstruction in type III tympanoplasties than are incus of foreign body interpositions. Adhesions on the promontory are found more often with fascia than with cartilage fragments. Histologic study of autograft cartilage showed good preservation of cartilage cells even 26 years after transplantation. The use of palisade cartilage technique brings very good functional and better long-term results.

Laser Ablation-Aerosol Mass Spectrometry-Chemical Ionization Mass Spectrometry for Ambient Surface Imaging

DOE PAGES

Berry, Jennifer L.; Day, Douglas A.; Elseberg, Tim; ...

2018-02-20

Mass spectrometry imaging is becoming an increasingly common analytical technique due to its ability to provide spatially resolved chemical information. In this paper, we report a novel imaging approach combining laser ablation with two mass spectrometric techniques, aerosol mass spectrometry and chemical ionization mass spectrometry, separately and in parallel. Both mass spectrometric methods provide the fast response, rapid data acquisition, low detection limits, and high-resolution peak separation desirable for imaging complex samples. Additionally, the two techniques provide complementary information with aerosol mass spectrometry providing near universal detection of all aerosol molecules and chemical ionization mass spectrometry with a heated inletmore » providing molecular-level detail of both gases and aerosols. The two techniques operate with atmospheric pressure interfaces and require no matrix addition for ionization, allowing for samples to be investigated in their native state under ambient pressure conditions. We demonstrate the ability of laser ablation-aerosol mass spectrometry-chemical ionization mass spectrometry (LA-AMS-CIMS) to create 2D images of both standard compounds and complex mixtures. Finally, the results suggest that LA-AMS-CIMS, particularly when combined with advanced data analysis methods, could have broad applications in mass spectrometry imaging applications.« less

Laser Ablation-Aerosol Mass Spectrometry-Chemical Ionization Mass Spectrometry for Ambient Surface Imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Berry, Jennifer L.; Day, Douglas A.; Elseberg, Tim

Mass spectrometry imaging is becoming an increasingly common analytical technique due to its ability to provide spatially resolved chemical information. In this paper, we report a novel imaging approach combining laser ablation with two mass spectrometric techniques, aerosol mass spectrometry and chemical ionization mass spectrometry, separately and in parallel. Both mass spectrometric methods provide the fast response, rapid data acquisition, low detection limits, and high-resolution peak separation desirable for imaging complex samples. Additionally, the two techniques provide complementary information with aerosol mass spectrometry providing near universal detection of all aerosol molecules and chemical ionization mass spectrometry with a heated inletmore » providing molecular-level detail of both gases and aerosols. The two techniques operate with atmospheric pressure interfaces and require no matrix addition for ionization, allowing for samples to be investigated in their native state under ambient pressure conditions. We demonstrate the ability of laser ablation-aerosol mass spectrometry-chemical ionization mass spectrometry (LA-AMS-CIMS) to create 2D images of both standard compounds and complex mixtures. Finally, the results suggest that LA-AMS-CIMS, particularly when combined with advanced data analysis methods, could have broad applications in mass spectrometry imaging applications.« less

Development of a new experimental device for long-duration magnetic reconnection in weakly ionized plasma

NASA Astrophysics Data System (ADS)

Yanai, Ryoma; Kaminou, Yasuhiro; Nishida, Kento; Inomoto, Michiaki

2016-10-01

Magnetic reconnection is a universal phenomenon which determines global structure and energy conversion in magnetized plasmas. Many experimental studies have been carried out to explore the physics of magnetic reconnection in fully ionized condition. However, it is predicted that the behavior of magnetic reconnection in weakly ionized plasmas such as solar chromosphere plasma will show different behavior such as ambipolar diffusion caused by interaction with neutral particles. In this research, we are developing a new experimental device to uncover the importance of ambipolar diffusion during magnetic reconnection in weakly ionized plasmas. We employ an inverter-driven rotating magnetic fields technique, which is used for generating steady azimuthal plasma current, to establish long-duration ( 1 ms) anti-parallel reconnection with magnetic field of 5 mT in weakly ionized plasma. We will present development status and initial results from the new experimental setup. This work was supported by JSPS A3 Foresight Program ``Innovative Tokamak Plasma Startup and Current Drive in Spherical Torus'', Giant-in Aid for Scientific Research (KAKENHI) 15H05750, 15K14279, 26287143 and the NIFS Collaboration Research program (NIFS14KNWP004).

Fuel cell plates with skewed process channels for uniform distribution of stack compression load

DOEpatents

Granata, Jr., Samuel J.; Woodle, Boyd M.

1989-01-01

An electrochemical fuel cell includes an anode electrode, a cathode electrode, an electrolyte matrix sandwiched between electrodes, and a pair of plates above and below the electrodes. The plate above the electrodes has a lower surface with a first group of process gas flow channels formed thereon and the plate below the electrodes has an upper surface with a second group of process gas flow channels formed thereon. The channels of each group extend generally parallel to one another. The improvement comprises the process gas flow channels on the lower surface of the plate above the anode electrode and the process gas flow channels on the upper surface of the plate below the cathode electrode being skewed in opposite directions such that contact areas of the surfaces of the plates through the electrodes are formed in crisscross arrangements. Also, the plates have at least one groove in areas of the surfaces thereof where the channels are absent for holding process gas and increasing electrochemical activity of the fuel cell. The groove in each plate surface intersects with the process channels therein. Also, the opposite surfaces of a bipolar plate for a fuel cell contain first and second arrangements of process gas flow channels in the respective surfaces which are skewed the same amount in opposite directions relative to the longitudinal centerline of the plate.

On the wall perturbation correction for a parallel-plate NACP-02 chamber in clinical electron beams.

PubMed

Zink, K; Wulff, J

2011-02-01

In recent years, several Monte Carlo studies have been published concerning the perturbation corrections of a parallel-plate chamber in clinical electron beams. In these studies, a strong depth dependence of the relevant correction factors (p(wall) and P(cav)) for depth beyond the reference depth is recognized and it has been shown that the variation with depth is sensitive to the choice of the chamber's effective point of measurement. Recommendations concerning the positioning of parallel-plate ionization chambers in clinical electron beams are not the same for all current dosimetry protocols. The IAEA TRS-398 as well as the IPEM protocol and the German protocol DIN 6800-2 interpret the depth of measurement within the phantom as the water equivalent depth, i.e., the nonwater equivalence of the entrance window has to be accounted for by shifting the chamber by an amount deltaz. This positioning should ensure that the primary electrons traveling from the surface of the water phantom through the entrance window to the chamber's reference point sustain the same energy loss as the primary electrons in the undisturbed phantom. The objective of the present study is the determination of the shift deltaz for a NACP-02 chamber and the calculation of the resulting wall perturbation correction as a function of depth. Moreover, the contributions of the different chamber walls to the wall perturbation correction are identified. The dose and fluence within the NACP-02 chamber and a wall-less air cavity is calculated using the Monte Carlo code EGSnrc in a water phantom at different depths for different clinical electron beams. In order to determine the necessary shift to account for the nonwater equivalence of the entrance window, the chamber is shifted in steps deltaz around the depth of measurement. The optimal shift deltaz is determined from a comparison of the spectral fluence within the chamber and the bare cavity. The wall perturbation correction is calculated as the ratio between doses for the complete chamber and a wall-less air cavity. The high energy part of the fluence spectra within the chamber strongly varies even with small chamber shifts, allowing the determination of deltaz within micrometers. For the NACP-02 chamber a shift deltaz = -0.058 cm results. This value is independent of the energy of the primary electrons as well as of the depth within the phantom and it is in good agreement with the value recommended in the German dosimetry protocol. Applying this shift, the calculated wall perturbation correction as a function of depth is varying less than 1% from zero up to the half value depth R50 for electron energies in the range of 6-21 MeV. The remaining depth dependence can mainly be attributed to the scatter properties of the entrance window. When neglecting the nonwater equivalence of the entrance window, the variation of p(wall) with depth is up to 10% and more, especially for low electron energies. The variation of the wall perturbation correction for the NACP-02 chamber in clinical electron beams strongly depends on the positioning of the chamber. Applying a shift deltaz = -0.058 cm toward the focus ensures that the primary electron spectrum within the chamber bears the largest resemblance to the fluence of a wall-less cavity. Hence, the influence of the chamber walls on the perturbation correction can be separated out and the residual variation of p(wall) with depth is minimized.

Isotope separation apparatus

DOEpatents

Arnush, Donald; MacKenzie, Kenneth R.; Wuerker, Ralph F.

1980-01-01

Isotope separation apparatus consisting of a plurality of cells disposed adjacent to each other in an evacuated container. A common magnetic field is established extending through all of the cells. A source of energetic electrons at one end of the container generates electrons which pass through the cells along the magnetic field lines. Each cell includes an array of collector plates arranged in parallel or in tandem within a common magnetic field. Sets of collector plates are disposed adjacent to each other in each cell. Means are provided for differentially energizing ions of a desired isotope by applying energy at the cyclotron resonant frequency of the desired isotope. As a result, the energized desired ions are preferentially collected by the collector plates.

A Fresnel zone plate collimator: potential and aberrations

NASA Astrophysics Data System (ADS)

Menz, Benedikt; Bräuninger, Heinrich; Burwitz, Vadim; Hartner, Gisela; Predehl, Peter

2015-09-01

A collimator, that parallelizes an X-ray beam, provides a significant improvement of the metrology to characterize X-ray optics for space instruments at MPE's PANTER X-ray test facility. A Fresnel zone plate was selected as a collimating optic, as it meets a good angular resolution < 0.1n combined with a large active area > 10 cm2. Such an optic is ideally suited to illuminate Silicon Pore Optic (SPO) modules as proposed for ATHENA. This paper provides the theoretic description of such a Fresnel zone plate especially considering resolution and efficiency. Based on the theoretic results the collimator setup performance is analyzed and requirements for fabrication and alignment are calculated.

A study of the effect of a boundary layer profile on the dynamic response and acoustic radiation of flat panels. Ph.D. Thesis - Virginia Univ.

NASA Technical Reports Server (NTRS)

Mixson, J. S.

1973-01-01

The response of a thin, elastic plate to a harmonic force which drives the plate from below and a compressible air stream with a viscous boundary layer flowing parallel to the upper surface along the length was investigated. Equations governing the forced response of the coupled plate-aerodynamic system are derived along with appropriate boundary conditions. Calculations of basic solution parameters for a linear velocity profile and for a Blasius profile showed that the same system response could be obtained from each profile if appropriate values of boundary layer thickness were chosen for each profile.

Laser beam guard clamps

DOEpatents

Dickson, Richard K.

2010-09-07

A quick insert and release laser beam guard panel clamping apparatus having a base plate mountable on an optical table, a first jaw affixed to the base plate, and a spring-loaded second jaw slidably carried by the base plate to exert a clamping force. The first and second jaws each having a face acutely angled relative to the other face to form a V-shaped, open channel mouth, which enables wedge-action jaw separation by and subsequent clamping of a laser beam guard panel inserted through the open channel mouth. Preferably, the clamping apparatus also includes a support structure having an open slot aperture which is positioned over and parallel with the open channel mouth.

Acoustic wave device using plate modes with surface-parallel displacement

DOEpatents

Martin, Stephen J.; Ricco, Antonio J.

1992-01-01

Solid-state acoustic sensors for monitoring conditions at a surface immersed in a liquid and for monitoring concentrations of species in a liquid and for monitoring electrical properties of a liquid are formed by placing interdigital input and output transducers on a piezoelectric substrate and propagating acoustic plate modes therebetween. The deposition or removal of material on or from, respectively, a thin film in contact with the surface, or changes in the mechanical properties of a thin film in contact with the surface, or changes in the electrical characteristics of the solution, create perturbations in the velocity and attenuation of the acoustic plate modes as a function of these properties or changes in them.

Acoustic wave device using plate modes with surface-parallel displacement

DOEpatents

Martin, S.J.; Ricco, A.J.

1992-05-26

Solid-state acoustic sensors for monitoring conditions at a surface immersed in a liquid and for monitoring concentrations of species in a liquid and for monitoring electrical properties of a liquid are formed by placing interdigital input and output transducers on a piezoelectric substrate and propagating acoustic plate modes there between. The deposition or removal of material on or from, respectively, a thin film in contact with the surface, or changes in the mechanical properties of a thin film in contact with the surface, or changes in the electrical characteristics of the solution, create perturbations in the velocity and attenuation of the acoustic plate modes as a function of these properties or changes in them. 6 figs.

Acoustic wave device using plate modes with surface-parallel displacement

DOEpatents

Martin, S.J.; Ricco, A.J.

1988-04-29

Solid-state acoustic sensors for monitoring conditions at a surface immersed in a liquid and for monitoring concentrations of species in a liquid and for monitoring electrical properties of a liquid are formed by placing interdigital input and output transducers on a piezoelectric substrate and propagating acoustic plate modes therebetween. The deposition or removal of material on or from, respectively, a thin film in contact with the surface, or changes in the mechanical properties of a thin film in contact with the surface, or changes in the electrical characteristics of the solution, create perturbations in the velocity and attenuation of the acoustic plate modes as a function of these properties or changes in them. 6 figs.

Strength of Rectangular Flat Plates Under Edge Compression

NASA Technical Reports Server (NTRS)

Schuman, Louis; Back, Goldie

1931-01-01

Flat rectangular plates of duralumin, stainless iron, monel metal, and nickel were tested under loads applied at two opposite edges and acting in the plane of the plate. The edges parallel to the direction of loading were supported in V grooves. The plates were all 24 inches long and varied in width from 4 to 24 inches by steps of 4 inches, and in thickness from 0.015 to 0.095 inch by steps of approximately 0.015 inch. There were also a few 1, 2, 3, and 6 inch wide specimens. The loads were applied in the testing machine at the center of a bar which rested along the top of the plate. Load was applied until the plate failed to take any more load. The tests show that the loads carried by the plates generally reached a maximum for the 8 or 12 inch width and that there was relatively small drop in load for the greater widths. Deflection and set measurement perpendicular to the plane of the plate were taken and the form of the buckle determined. The number of buckles were found to correspond in general to that predicted by the theory of buckling of a plate uniformly loaded at two opposite edges and simply supported at the edges.

Plate refractive camera model and its applications

NASA Astrophysics Data System (ADS)

Huang, Longxiang; Zhao, Xu; Cai, Shen; Liu, Yuncai

2017-03-01

In real applications, a pinhole camera capturing objects through a planar parallel transparent plate is frequently employed. Due to the refractive effects of the plate, such an imaging system does not comply with the conventional pinhole camera model. Although the system is ubiquitous, it has not been thoroughly studied. This paper aims at presenting a simple virtual camera model, called a plate refractive camera model, which has a form similar to a pinhole camera model and can efficiently model refractions through a plate. The key idea is to employ a pixel-wise viewpoint concept to encode the refraction effects into a pixel-wise pinhole camera model. The proposed camera model realizes an efficient forward projection computation method and has some advantages in applications. First, the model can help to compute the caustic surface to represent the changes of the camera viewpoints. Second, the model has strengths in analyzing and rectifying the image caustic distortion caused by the plate refraction effects. Third, the model can be used to calibrate the camera's intrinsic parameters without removing the plate. Last but not least, the model contributes to putting forward the plate refractive triangulation methods in order to solve the plate refractive triangulation problem easily in multiviews. We verify our theory in both synthetic and real experiments.

Experimental Technique and Assessment for Measuring the Convective Heat Transfer Coefficient from Natural Ice Accretions

NASA Technical Reports Server (NTRS)

Masiulaniec, K. Cyril; Vanfossen, G. James, Jr.; Dewitt, Kenneth J.; Dukhan, Nihad

1995-01-01

A technique was developed to cast frozen ice shapes that had been grown on a metal surface. This technique was applied to a series of ice shapes that were grown in the NASA Lewis Icing Research Tunnel on flat plates. Nine flat plates, 18 inches square, were obtained from which aluminum castings were made that gave good ice shape characterizations. Test strips taken from these plates were outfitted with heat flux gages, such that when placed in a dry wind tunnel, can be used to experimentally map out the convective heat transfer coefficient in the direction of flow from the roughened surfaces. The effects on the heat transfer coefficient for both parallel and accelerating flow will be studied. The smooth plate model verification baseline data as well as one ice roughened test case are presented.

Proceedings of the Flat-Plate Solar Array Project Research Forum on the Design of Flat-Plate Photovoltaic Arrays for Central Stations

NASA Technical Reports Server (NTRS)

1983-01-01

The Flat Plate Solar Array Project, focuses on advancing technologies relevant to the design and construction of megawatt level central station systems. Photovoltaic modules and arrays for flat plate central station or other large scale electric power production facilities require the establishment of a technical base that resolves design issues and results in practical and cost effective configurations. Design, qualification and maintenance issues related to central station arrays derived from the engineering and operating experiences of early applications and parallel laboratory reserch activities are investigated. Technical issues are examined from the viewpoint of the utility engineer, architect/engineer and laboratory researcher. Topics on optimum source circuit designs, module insulation design for high system voltages, array safety, structural interface design, measurements, and array operation and maintenance are discussed.

Inspiration of slip effects on electromagnetohydrodynamics (EMHD) nanofluid flow through a horizontal Riga plate

NASA Astrophysics Data System (ADS)

Ayub, M.; Abbas, T.; Bhatti, M. M.

2016-06-01

The boundary layer flow of nanofluid that is electrically conducting over a Riga plate is considered. The Riga plate is an electromagnetic actuator which comprises a spanwise adjusted cluster of substituting terminal and lasting magnets mounted on a plane surface. The numerical model fuses the Brownian motion and the thermophoresis impacts because of the nanofluid and the Grinberg term for the wall parallel Lorentz force due to the Riga plate in the presence of slip effects. The numerical solution of the problem is presented using the shooting method. The novelties of all the physical parameters such as modified Hartmann number, Richardson number, nanoparticle concentration flux parameter, Prandtl number, Lewis number, thermophoresis parameter, Brownian motion parameter and slip parameter are demonstrated graphically. Numerical values of reduced Nusselt number, Sherwood number are discussed in detail.

LABORATORY ANALYSES OF CORONA DISCHARGES

EPA Science Inventory

The paper discusses an experimental research program to characterize corona generation from different electrode geometries in a range of conditions comparable to those found in electrostatic precipitators (ESPs). A wire-parallel plate device and a wire-cylinder device were used t...

LABORATORY ANALYSIS OF BACK-CORONA DISCHARGE

EPA Science Inventory

The paper discusses an experimental research program to characterize back-corona generation and behavior in a range of environments and geometries common to electrostatic precipitators (ESPs). A wire-parallel plate device was used to monitor the intensity and distribution of back...

Experimental Evidence for Quantum Tunneling Time.

PubMed

Camus, Nicolas; Yakaboylu, Enderalp; Fechner, Lutz; Klaiber, Michael; Laux, Martin; Mi, Yonghao; Hatsagortsyan, Karen Z; Pfeifer, Thomas; Keitel, Christoph H; Moshammer, Robert

2017-07-14

The first hundred attoseconds of the electron dynamics during strong field tunneling ionization are investigated. We quantify theoretically how the electron's classical trajectories in the continuum emerge from the tunneling process and test the results with those achieved in parallel from attoclock measurements. An especially high sensitivity on the tunneling barrier is accomplished here by comparing the momentum distributions of two atomic species of slightly deviating atomic potentials (argon and krypton) being ionized under absolutely identical conditions with near-infrared laser pulses (1300 nm). The agreement between experiment and theory provides clear evidence for a nonzero tunneling time delay and a nonvanishing longitudinal momentum of the electron at the "tunnel exit."

Experimental Evidence for Quantum Tunneling Time

NASA Astrophysics Data System (ADS)

Camus, Nicolas; Yakaboylu, Enderalp; Fechner, Lutz; Klaiber, Michael; Laux, Martin; Mi, Yonghao; Hatsagortsyan, Karen Z.; Pfeifer, Thomas; Keitel, Christoph H.; Moshammer, Robert

2017-07-01

The first hundred attoseconds of the electron dynamics during strong field tunneling ionization are investigated. We quantify theoretically how the electron's classical trajectories in the continuum emerge from the tunneling process and test the results with those achieved in parallel from attoclock measurements. An especially high sensitivity on the tunneling barrier is accomplished here by comparing the momentum distributions of two atomic species of slightly deviating atomic potentials (argon and krypton) being ionized under absolutely identical conditions with near-infrared laser pulses (1300 nm). The agreement between experiment and theory provides clear evidence for a nonzero tunneling time delay and a nonvanishing longitudinal momentum of the electron at the "tunnel exit."

Equation of motion coupled cluster methods for electron attachment and ionization potential in fullerenes C60 and C70

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bhaskaran-Nair, Kiran; Kowalski, Karol; Moreno, Juana

Discovery of fullerenes has opened a entirely new chapter in chemistry due to their wide range of properties which holds exciting applications in numerous disciplines of science. The Nobel Prize in Chemistry 1996 was awarded jointly to Robert F. Curl Jr., Sir Harold W. Kroto and Richard E. Smalley in recoginition for their discovery of this new carbon allotrope. In this letter we are reporting ionization potential and electron attachment studies on fullerenes (C60 and C70) obtained with novel parallel implementation of the EA-EOM-CCSD and IP-EOM-CCSD methods in NWChem program package.

Transmission geometry laserspray ionization vacuum using an atmospheric pressure inlet.

PubMed

Lutomski, Corinne A; El-Baba, Tarick J; Inutan, Ellen D; Manly, Cory D; Wager-Miller, James; Mackie, Ken; Trimpin, Sarah

2014-07-01

This represents the first report of laserspray ionization vacuum (LSIV) with operation directly from atmospheric pressure for use in mass spectrometry. Two different types of electrospray ionization source inlets were converted to LSIV sources by equipping the entrance of the atmospheric pressure inlet aperture with a customized cone that is sealed with a removable glass plate holding the matrix/analyte sample. A laser aligned in transmission geometry (at 180° relative to the inlet) ablates the matrix/analyte sample deposited on the vacuum side of the glass slide. Laser ablation from vacuum requires lower inlet temperature relative to laser ablation at atmospheric pressure. However, higher inlet temperature is required for high-mass analytes, for example, α-chymotrypsinogen (25.6 kDa). Labile compounds such as gangliosides and cardiolipins are detected in the negative ion mode directly from mouse brain tissue as intact doubly deprotonated ions. Multiple charging enhances the ion mobility spectrometry separation of ions derived from complex tissue samples.

Transmission Geometry Laserspray Ionization Vacuum Using an Atmospheric Pressure Inlet

PubMed Central

2015-01-01

This represents the first report of laserspray ionization vacuum (LSIV) with operation directly from atmospheric pressure for use in mass spectrometry. Two different types of electrospray ionization source inlets were converted to LSIV sources by equipping the entrance of the atmospheric pressure inlet aperture with a customized cone that is sealed with a removable glass plate holding the matrix/analyte sample. A laser aligned in transmission geometry (at 180° relative to the inlet) ablates the matrix/analyte sample deposited on the vacuum side of the glass slide. Laser ablation from vacuum requires lower inlet temperature relative to laser ablation at atmospheric pressure. However, higher inlet temperature is required for high-mass analytes, for example, α-chymotrypsinogen (25.6 kDa). Labile compounds such as gangliosides and cardiolipins are detected in the negative ion mode directly from mouse brain tissue as intact doubly deprotonated ions. Multiple charging enhances the ion mobility spectrometry separation of ions derived from complex tissue samples. PMID:24896880

Easy ambient sonic-spray ionization mass spectrometry combined with thin-layer chromatography.

PubMed

Haddad, Renato; Milagre, Humberto M S; Catharino, Rodrigo Ramos; Eberlin, Marcos N

2008-04-15

On-spot detection and analyte characterization on thin-layer chromatography (TLC) plates is performed via ambient desorption/ionization and (tandem) mass spectrometry detection, that is, via easy ambient sonic spray ionization mass spectrometry (EASI-MS). As proof-of-principle cases, mixtures of semipolar nitrogenated compounds as well as pharmaceutical drugs and vegetable oils have been tested. The technique has also been applied to monitor a chemical reaction of synthetic importance. EASI is the simplest and gentlest ambient ionization technique currently available, assisted solely by N2 (or air). It uses no voltages, no electrical discharges; no UV or laser beams, and no high temperature and is most easily implemented in all API mass spectrometers. TLC is also the simplest, fastest, and most easily performed chromatographic technique. TLC plus EASI-MS therefore provide a simple and advantageous combination of chromatographic separation and sensitive detection of the TLC spots as well as on-spot MS or MS/MS characterization. The favorable characteristics of TLC-EASI-MS indicate advantageous applications in several areas such as drug and oil analysis, phytochemistry and synthetic chemistry, forensics via reliable counterfeit detection, and quality control.

MO-F-CAMPUS-T-05: Design of An Innovative Beam Monitor for Particle Therapy for the Simultaneous Measurement of Beam Fluence and Energy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sacchi, R; Guarachi, L Fanola; Monaco, V

2015-06-15

Purpose: Monitoring the prescribed dose in particle therapy is typically carried out by using parallel plate ionization chambers working in transmission mode. The use of gas detectors has several drawbacks: they need to be calibrated daily against standard dosimeters and their dependence on beam quality factors need to be fully characterized and controlled with high accuracy. A detector capable of single particle counting is proposed which would overcome all these limitations. Combined with a gas ionization chamber, it will allow determining the average particle stopping power, thus providing an effective method for the online verification of the selected particle energymore » and range. Methods: Low-Gain Avalanche Detectors (LGADs) are innovative n-in-p silicon sensors with moderate internal charge multiplication occurring in the strong field generated by an additional p+ doping layer implanted at a depth of a few µm in the bulk of the sensor. The increased signal-to-noise ratio allows designing very thin, few tens of microns, segmented LGADs, called Ultra Fast Silicon Detectors (UFSD), optimized for very fast signal, which would be suitable for charged particle counting at high rates. A prototype UFSD is being designed for this purpose. Results: Different LGAD diodes have been characterized both in laboratory and beam tests, and the results compared both with those obtained with similar diodes without the gain layer and with a program simulating the signal in the sensors. The signal is found to be enhanced in LGADs, while the leakage current and the noise is not affected by the gain. Possible alternative designs and implementations are also presented and discussed. Conclusion: Thanks to their excellent counting capabilities, UFSD detectors are a promising technology for future beam monitor devices in hadron-therapy applications. Studies are ongoing to better understand their properties and optimize the design in view of this application.« less

SU-F-T-669: Commissioning of An Electronic Brachytherapy System for Targeted Mouse Irradiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Culberson, W; Micka, J; Carchman, E

Purpose: The aim of this study was to commission the Xoft Axxent™ electronic brachytherapy (eBT) source and 10 mm diameter surface applicator with NIST traceability for targeted irradiations of mouse anal carcinomas. Methods: The Xoft Axxent™ electronic brachytherapy (eBT) and 10 mm diameter surface applicator was chosen by the collaborating physician as a radiation delivery mechanism for mouse anal carcinomas. The target dose was 2 Gy at a depth of 3 mm in tissue to be delivered in a single fraction. To implement an accurate and reliable irradiation plan, the system was commissioned by first determining the eBT source outputmore » and corresponding dose rate at a depth of 3 mm in tissue. This was determined through parallel-plate ion chamber measurements and published conversion factors. Well-type ionization chamber measurements were used to determine a transfer coefficient, which correlates the measured dose rate at 3 mm to the NIST-traceable quantity, air-kerma rate at 50 cm in air, for eBT sources. By correlating these two quantities, daily monitoring in the well chamber becomes an accurate and efficient quality assurance technique. Once the dose-rate was determined, a treatment recipe was developed and confirmed with chamber measurements to deliver the requested dose. Radiochromic film was used to verify the dose distribution across the field. Results: Dose rates at 3 mm depth in tissue were determined for two different Xoft Axxent™ sources and correlated with NIST-traceable well-type ionization chamber measurements. Unique transfer coefficients were determined for each source and the treatment recipe was validated by measurements. Film profiles showed a uniform dose distribution across the field. Conclusion: A Xoft Axxent™ eBT system was successfully commissioned for use in the irradiation of mouse rectal tumors. Dose rates in tissue were determined as well as other pertinent parameters to ensure accurate delivery of dose to the target region.« less

Martian plate tectonics

NASA Astrophysics Data System (ADS)

Sleep, N. H.

1994-03-01

The northern lowlands of Mars have been produced by plate tectonics. Preexisting old thick highland crust was subducted, while seafloor spreading produced thin lowland crust during late Noachian and Early Hesperian time. In the preferred reconstruction, a breakup margin extended north of Cimmeria Terra between Daedalia Planum and Isidis Planitia where the highland-lowland transition is relatively simple. South dipping subduction occured beneath Arabia Terra and east dipping subduction beneath Tharsis Montes and Tempe Terra. Lineations associated with Gordii Dorsum are attributed to ridge-parallel structures, while Phelegra Montes and Scandia Colles are interpreted as transfer-parallel structures or ridge-fault-fault triple junction tracks. Other than for these few features, there is little topographic roughness in the lowlands. Seafloor spreading, if it occurred, must have been relatively rapid. Quantitative estimates of spreading rate are obtained by considering the physics of seafloor spreading in the lower (approx. 0.4 g) gravity of Mars, the absence of vertical scarps from age differences across fracture zones, and the smooth axial topography. Crustal thickness at a given potential temperature in the mantle source region scales inversely with gravity. Thus, the velocity of the rough-smooth transition for axial topography also scales inversely with gravity. Plate reorganizations where young crust becomes difficult to subduct are another constraint on spreading age. Plate tectonics, if it occurred, dominated the thermal and stress history of the planet. A geochemical implication is that the lower gravity of Mars allows deeper hydrothermal circulation through cracks and hence more hydration of oceanic crust so that more water is easily subducted than on the Earth. Age and structural relationships from photogeology as well as median wavelength gravity anomalies across the now dead breakup and subduction margins are the data most likely to test and modify hypotheses about Mars plate tectonics.

Enhancing Sensitivity of Liquid Chromatography-Mass Spectrometry of Peptides and Proteins Using Supercharging Agents.

PubMed

Nshanian, Michael; Lakshmanan, Rajeswari; Chen, Hao; Ogorzalek Loo, Rachel R; Loo, Joseph A

2018-04-01

Trifluoroacetic acid (TFA) is often used as a mobile phase modifier to enhance reversed phase chromatographic performance. TFA adjusts solution pH and is an ion-pairing agent, but it is not typically suitable for electrospray ionization-mass spectrometry (ESI-MS) and liquid chromatography/MS (LC/MS) because of its significant signal suppression. Supercharging agents elevate peptide and protein charge states in ESI, increasing tandem MS (MS/MS) efficiency. Here, LC/MS protein supercharging was effected by adding agents to LC mobile phase solvents. Significantly, the ionization suppression generally observed with TFA was, for the most part, rescued by supercharging agents, with improved separation efficiency (higher number of theoretical plates) and lowered detection limits.

Modeling of the energy resolution of a 1 meter and a 3 meter time of flight positron annihilation induced Auger electron spectrometers

NASA Astrophysics Data System (ADS)

Fairchild, A.; Chirayath, V.; Gladen, R.; McDonald, A.; Lim, Z.; Chrysler, M.; Koymen, A.; Weiss, A.

Simion 8.1®simulations were used to determine the energy resolution of a 1 meter long Time of Flight Positron annihilation induced Auger Electron Spectrometer (TOF-PAES). The spectrometer consists of: 1. a magnetic gradient section used to parallelize the electrons leaving the sample along the beam axis, 2. an electric field free time of flight tube and 3. a detection section with a set of ExB plates that deflect electrons exiting the TOF tube into a Micro-Channel Plate (MCP). Simulations of the time of flight distribution of electrons emitted according to a known secondary electron emission distribution, for various sample biases, were compared to experimental energy calibration peaks and found to be in excellent agreement. The TOF spectra at the highest sample bias was used to determine the timing resolution function describing the timing spread due to the electronics. Simulations were then performed to calculate the energy resolution at various electron energies in order to deconvolute the combined influence of the magnetic field parallelizer, the timing resolution, and the voltage gradient at the ExB plates. The energy resolution of the 1m TOF-PAES was compared to a newly constructed 3 meter long system. The results were used to optimize the geometry and the potentials of the ExB plates for obtaining the best energy resolution. This work was supported by NSF Grant NSF Grant No. DMR 1508719 and DMR 1338130.

MPI_XSTAR: MPI-based parallelization of XSTAR program

NASA Astrophysics Data System (ADS)

Danehkar, A.

2017-12-01

MPI_XSTAR parallelizes execution of multiple XSTAR runs using Message Passing Interface (MPI). XSTAR (ascl:9910.008), part of the HEASARC's HEAsoft (ascl:1408.004) package, calculates the physical conditions and emission spectra of ionized gases. MPI_XSTAR invokes XSTINITABLE from HEASoft to generate a job list of XSTAR commands for given physical parameters. The job list is used to make directories in ascending order, where each individual XSTAR is spawned on each processor and outputs are saved. HEASoft's XSTAR2TABLE program is invoked upon the contents of each directory in order to produce table model FITS files for spectroscopy analysis tools.

Low Temperature (30 K) TID Test Results of a Radiation Hardened 128 Channel Serial-to-Parallel Converter

NASA Technical Reports Server (NTRS)

Meyer, Stephen; Buchner, Stephen; Moseley, Harvey; Ray, Knute; Tuttle, Jim; Quinn, Ed; Buchanan, Ernie; Bloom, Dave; Hait, Tom; Pearce, Mike;

Parallel mass spectrometry (APCI-MS and ESI-MS) for lipid analysis

USDA-ARS?s Scientific Manuscript database

Coupling the condensed phase of HPLC with the high vacuum necessary for ion analysis in a mass spectrometer requires quickly evaporating large amounts of liquid mobile phase to release analyte molecules into the gas phase, along with ionization of those molecules, so they can be detected by the mass...

Comparison of the IAEA TRS-398 and AAPM TG-51 absorbed dose to water protocols in the dosimetry of high-energy photon and electron beams

NASA Astrophysics Data System (ADS)

Saiful Huq, M.; Andreo, Pedro; Song, Haijun

2001-11-01

The International Atomic Energy Agency (IAEA TRS-398) and the American Association of Physicists in Medicine (AAPM TG-51) have published new protocols for the calibration of radiotherapy beams. These protocols are based on the use of an ionization chamber calibrated in terms of absorbed dose to water in a standards laboratory's reference quality beam. This paper compares the recommendations of the two protocols in two ways: (i) by analysing in detail the differences in the basic data included in the two protocols for photon and electron beam dosimetry and (ii) by performing measurements in clinical photon and electron beams and determining the absorbed dose to water following the recommendations of the two protocols. Measurements were made with two Farmer-type ionization chambers and three plane-parallel ionization chamber types in 6, 18 and 25 MV photon beams and 6, 8, 10, 12, 15 and 18 MeV electron beams. The Farmer-type chambers used were NE 2571 and PTW 30001, and the plane-parallel chambers were a Scanditronix-Wellhöfer NACP and Roos, and a PTW Markus chamber. For photon beams, the measured ratios TG-51/TRS-398 of absorbed dose to water Dw ranged between 0.997 and 1.001, with a mean value of 0.999. The ratios for the beam quality correction factors kQ were found to agree to within about +/-0.2% despite significant differences in the method of beam quality specification for photon beams and in the basic data entering into kQ. For electron beams, dose measurements were made using direct ND,w calibrations of cylindrical and plane-parallel chambers in a 60Co gamma-ray beam, as well as cross-calibrations of plane-parallel chambers in a high-energy electron beam. For the direct ND,w calibrations the ratios TG-51/TRS-398 of absorbed dose to water Dw were found to lie between 0.994 and 1.018 depending upon the chamber and electron beam energy used, with mean values of 0.996, 1.006, and 1.017, respectively, for the cylindrical, well-guarded and not well-guarded plane-parallel chambers. The Dw ratios measured for the cross-calibration procedures varied between 0.993 and 0.997. The largest discrepancies for electron beams between the two protocols arise from the use of different data for the perturbation correction factors pwall and pdis of cylindrical and plane-parallel chambers, all in 60Co. A detailed analysis of the reasons for the discrepancies is made which includes comparing the formalisms, correction factors and the quantities in the two protocols.

Particle in cell/Monte Carlo collision analysis of the problem of identification of impurities in the gas by the plasma electron spectroscopy method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kusoglu Sarikaya, C.; Rafatov, I., E-mail: rafatov@metu.edu.tr; Kudryavtsev, A. A.

2016-06-15

The work deals with the Particle in Cell/Monte Carlo Collision (PIC/MCC) analysis of the problem of detection and identification of impurities in the nonlocal plasma of gas discharge using the Plasma Electron Spectroscopy (PLES) method. For this purpose, 1d3v PIC/MCC code for numerical simulation of glow discharge with nonlocal electron energy distribution function is developed. The elastic, excitation, and ionization collisions between electron-neutral pairs and isotropic scattering and charge exchange collisions between ion-neutral pairs and Penning ionizations are taken into account. Applicability of the numerical code is verified under the Radio-Frequency capacitively coupled discharge conditions. The efficiency of the codemore » is increased by its parallelization using Open Message Passing Interface. As a demonstration of the PLES method, parallel PIC/MCC code is applied to the direct current glow discharge in helium doped with a small amount of argon. Numerical results are consistent with the theoretical analysis of formation of nonlocal EEDF and existing experimental data.« less

Plate Kinematic model of the NW Indian Ocean and derived regional stress history of the East African Margin

NASA Astrophysics Data System (ADS)

Tuck-Martin, Amy; Adam, Jürgen; Eagles, Graeme

2015-04-01

Starting with the break up of Gondwana, the northwest Indian Ocean and its continental margins in Madagascar, East Africa and western India formed by divergence of the African and Indian plates and were shaped by a complicated sequence of plate boundary relocations, ridge propagation events, and the independent movement of the Seychelles microplate. As a result, attempts to reconcile the different plate-tectonic components and processes into a coherent kinematic model have so far been unsatisfactory. A new high-resolution plate kinematic model has been produced in an attempt to solve these problems, using seafloor spreading data and rotation parameters generated by a mixture of visual fitting of magnetic isochron data and iterative joint inversion of magnetic isochron and fracture zone data. Using plate motion vectors and plate boundary geometries derived from this model, the first-order regional stress pattern was modelled for distinct phases of margin formation. The stress pattern is correlated with the tectono-stratigraphic history of related sedimentary basins. The plate kinematic model identifies three phases of spreading, from the Jurassic to the Paleogene, which resulted in the formation of three main oceanic basins. Prior to these phases, intracontinental 'Karoo' rifting episodes in the late Carboniferous to late Triassic had failed to break up Gondwana, but initiated the formation of sedimentary basins along the East African and West Madagascan margins. At the start of the first phase of spreading (183 to 133 Ma) predominantly NW - SE extension caused continental rifting that separated Madagascar/India/Antarctica from Africa. Maximum horizontal stresses trended perpendicular to the local plate-kinematic vector, and parallel to the rift axes. During and after continental break-up and subsequent spreading, the regional stress regime changed drastically. The extensional stress regime became restricted to the active spreading ridges that in turn adopted trends normal to the plate divergence vector. Away from the active ridges, compressional horizontal stresses caused by ridge-push forces were transmitted through the subsiding oceanic lithosphere, with an SH max orientation parallel to plate divergence vectors. These changes are documented by the lower Bajocian continental breakup unconformity, which can be traced throughout East African basins. At 133 Ma, the plate boundary moved from north to south of Madagascar, incorporating it into the African plate and initiating its separation from Antarctica. The orientation of the plate divergence vector however did not change markedly. The second phase (89 - 61 Ma) led to the separation of India from Madagascar, initiating a new and dramatic change in stress orientation from N-S to ENE-WSW. This led to renewed tectonic activity in the sedimentary basins of western Madagascar. In the third phase (61 Ma to present) asymmetric spreading of the Carlsberg Ridge separated India from the Seychelles and the Mascarene Plateau via the southward propagation of the Carlsberg Ridge to form the Central Indian Ridge. The anti-clockwise rotation of the independent Seychelles microplate between chrons 28n (64.13 Ma) and 26n (58.38 Ma) and the opening of the short-lived Laxmi Basin (67 Ma to abandonment within chron 28n (64.13 - 63.10 Ma)) have been further constrained by the new plate kinematic model. Along the East African margin, SH max remained in a NE - SW orientation and the sedimentary basins experienced continued thick, deep water sediment deposition. Contemporaneously, in the sedimentary basins along East African passive margin, ridge-push related maximum horizontal stresses became progressively outweighed by local gravity-driven NE-SW maximum horizontal stresses trending parallel to the margin. These stress regimes are caused by sediment loading and extensional collapse of thick sediment wedges, predominantly controlled by margin geometry. Our study successfully integrates an interpretation of paleo-stress regimes constrained by the new high resolution plate kinematic and basin history to produce a margin scale tectono-stratigraphic framework that highlights the important interplay of plate boundary forces and basin formation events along the East African margin.

Droplet-based magnetic bead immunoassay using microchannel-connected multiwell plates (μCHAMPs) for the detection of amyloid beta oligomers.

PubMed

Park, Min Cheol; Kim, Moojong; Lim, Gun Taek; Kang, Sung Min; An, Seong Soo A; Kim, Tae Song; Kang, Ji Yoon

2016-06-21

Multiwell plates are regularly used in analytical research and clinical diagnosis but often require laborious washing steps and large sample or reagent volumes (typically, 100 μL per well). To overcome such drawbacks in the conventional multiwell plate, we present a novel microchannel-connected multiwell plate (μCHAMP) that can be used for automated disease biomarker detection in a small sample volume by performing droplet-based magnetic bead immunoassay inside the plate. In this μCHAMP-based immunoassay platform, small volumes (30-50 μL) of aqueous-phase working droplets are stably confined within each well by the simple microchannel structure (200-300 μm in height and 0.5-1 mm in width), and magnetic beads are exclusively transported into an adjacent droplet through the oil-filled microchannels assisted by a magnet array aligned beneath and controlled by a XY-motorized stage. Using this μCHAMP-based platform, we were able to perform parallel detection of synthetic amyloid beta (Aβ) oligomers as a model analyte for the early diagnosis of Alzheimer's disease (AD). This platform easily simplified the laborious and consumptive immunoassay procedure by achieving automated parallel immunoassay (32 assays per operation in 3-well connected 96-well plate) within 1 hour and at low sample consumption (less than 10 μL per assay) with no cumbersome manual washing step. Moreover, it could detect synthetic Aβ oligomers even below 10 pg mL(-1) concentration with a calculated detection limit of ∼3 pg mL(-1). Therefore, the μCHAMP and droplet-based magnetic bead immunoassay, with the combination of XY-motorized magnet array, would be a useful platform in the diagnosis of human disease, including AD, which requires low consumption of the patient's body fluid sample and automation of the entire immunoassay procedure for high processing capacity.

Amplitude and Wavelength Measurement of Sound Waves in Free Space using a Sound Wave Phase Meter

NASA Astrophysics Data System (ADS)

Ham, Sounggil; Lee, Kiwon

2018-05-01

We developed a sound wave phase meter (SWPM) and measured the amplitude and wavelength of sound waves in free space. The SWPM consists of two parallel metal plates, where the front plate was operated as a diaphragm. An aluminum perforated plate was additionally installed in front of the diaphragm, and the same signal as that applied to the sound source was applied to the perforated plate. The SWPM measures both the sound wave signal due to the diaphragm vibration and the induction signal due to the electric field of the aluminum perforated plate. Therefore, the two measurement signals interfere with each other due to the phase difference according to the distance between the sound source and the SWPM, and the amplitude of the composite signal that is output as a result is periodically changed. We obtained the wavelength of the sound wave from this periodic amplitude change measured in the free space and compared it with the theoretically calculated values.