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Sample records for rod reactivity measurements

  1. Measurements of control rod efficiency in RBMK critical assembly upon dropping of the rods

    SciTech Connect

    Zhitarev, V. E. Kachanov, V. M.; Sergevnin, A. Yu.; Lebedev, G. V.

    2014-12-15

    The efficiency of control rods in the RBMK critical assembly was measured in the case where one manual-control rod (MCR) is dropped from a steady critical state, and several other MCRs were additionally dropped after 44 s. The measured number of neutrons in the assembly during and after dropping of the rods was used to calculate the efficiency values of the rods by solution of the system of point kinetics equations. A series of methods of the initial data treatment for determination of the desired values of reactivity without the calculated corrections were used.

  2. Methodology of the Westinghouse dynamic rod worth measurement technique

    SciTech Connect

    Chao, Y.A.; Chapman, D.M.; Easter, M.E.; Hill, D.J.; Hoerner, J.A. ); Kurtz, P.N. )

    1992-01-01

    During zero-power physics testing, plant operations personnel use one of various techniques to measure the reactivity worth of the control rods to confirm shutdown margin. A simple and fast procedure for measuring rod worths called dynamic rod worth measurement (DRWM) has been developed at Westinghouse. This procedure was tested at the recent startups of Point Beach Nuclear Power Plant Unit 1 cycle 20 and Unit 2 cycle 18. The results of these tests show that DRWM measures rod worths with accuracy comparable to that of both boron dilution and rod bank exchange measurements. The DRWM procedure is a fast process of measuring the reactivity worth of individual banks by inserting and withdrawing the bank continuously at the maximum stepping speed without changing the boron concentration and recording the signals of the ex-core detectors.

  3. Control rod calibration and reactivity effects at the IPEN/MB-01 reactor

    SciTech Connect

    Pinto, Letícia Negrão; Gonnelli, Eduardo; Santos, Adimir dos

    2014-11-11

    Researches that aim to improve the performance of neutron transport codes and quality of nuclear cross section databases are very important to increase the accuracy of simulations and the quality of the analysis and prediction of phenomena in the nuclear field. In this context, relevant experimental data such as reactivity worth measurements are needed. Control rods may be made of several neutron absorbing materials that are used to adjust the reactivity of the core. For the reactor operation, these experimental data are also extremely important: with them it is possible to estimate the reactivity worth by the movement of the control rod, understand the reactor response at each rod position and to operate the reactor safely. This work presents a temperature correction approach for the control rod calibration problem. It is shown the control rod calibration data of the IPEN/MB-01 reactor, the integral and differential reactivity curves and a theoretical analysis, performed by the MCNP-5 reactor physics code, developed and maintained by Los Alamos National Laboratory, using the ENDF/B-VII.0 nuclear data library.

  4. Hybrid nuclear reactor grey rod to obtain required reactivity worth

    DOEpatents

    Miller, John V.; Carlson, William R.; Yarbrough, Michael B.

    1991-01-01

    Hybrid nuclear reactor grey rods are described, wherein geometric combinations of relatively weak neutron absorber materials such as stainless steel, zirconium or INCONEL, and relatively strong neutron absorber materials, such as hafnium, silver-indium cadmium and boron carbide, are used to obtain the reactivity worths required to reach zero boron change load follow. One embodiment includes a grey rod which has combinations of weak and strong neutron absorber pellets in a stainless steel cladding. The respective pellets can be of differing heights. A second embodiment includes a grey rod with a relatively thick stainless steel cladding receiving relatively strong neutron absorber pellets only. A third embodiment includes annular relatively weak netron absorber pellets with a smaller diameter pellet of relatively strong absorber material contained within the aperture of each relatively weak absorber pellet. The fourth embodiment includes pellets made of a homogeneous alloy of hafnium and a relatively weak absorber material, with the percentage of hafnium chosen to obtain the desired reactivity worth.

  5. Image analysis for measuring rod network properties

    NASA Astrophysics Data System (ADS)

    Kim, Dongjae; Choi, Jungkyu; Nam, Jaewook

    2015-12-01

    In recent years, metallic nanowires have been attracting significant attention as next-generation flexible transparent conductive films. The performance of films depends on the network structure created by nanowires. Gaining an understanding of their structure, such as connectivity, coverage, and alignment of nanowires, requires the knowledge of individual nanowires inside the microscopic images taken from the film. Although nanowires are flexible up to a certain extent, they are usually depicted as rigid rods in many analysis and computational studies. Herein, we propose a simple and straightforward algorithm based on the filtering in the frequency domain for detecting the rod-shape objects inside binary images. The proposed algorithm uses a specially designed filter in the frequency domain to detect image segments, namely, the connected components aligned in a certain direction. Those components are post-processed to be combined under a given merging rule in a single rod object. In this study, the microscopic properties of the rod networks relevant to the analysis of nanowire networks were measured for investigating the opto-electric performance of transparent conductive films and their alignment distribution, length distribution, and area fraction. To verify and find the optimum parameters for the proposed algorithm, numerical experiments were performed on synthetic images with predefined properties. By selecting proper parameters, the algorithm was used to investigate silver nanowire transparent conductive films fabricated by the dip coating method.

  6. Evaluation of differential shim rod worth measurements in the Oak Ridge Research Reactor

    SciTech Connect

    Bretscher, M.M.

    1987-01-01

    Reasonable agreement between calculated and measured differential shim rod worths in the Oak Ridge Research Reactor (ORR) has been achieved by taking into account the combined effects of negative reactivity contributions from changing fuel-moderator temperatures and of delayed photoneutrons. A method has been developed for extracting the asymptotic period from the shape of the initial portion of the measured time-dependent neutron flux profile following a positive reactivity insertion. In this region of the curve temperature-related reactivity feedback effects are negligibly small. Results obtained by applying this technique to differential shim rod worth measurements made in a wide variety of ORR cores are presented.

  7. Measurement of the Speed of Sound in a Metal Rod.

    ERIC Educational Resources Information Center

    Mak, Se-yuen; Ng, Yee-kong; Wu, Kam-wah

    2000-01-01

    Suggests two improved methods to measure the speed of sound in a metal rod. One employs a fast timer to measure the time required for a compression pulse to travel along the rod from end to end, and a second uses a microphone to measure the frequency of the fundamental mode of a freely suspending singing rod. (Author/ASK)

  8. REACTIVITY MEASUREMENT FACILITY. CAMERA LOOKS DOWN INTO MTR CANAL. REACTOR ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    REACTIVITY MEASUREMENT FACILITY. CAMERA LOOKS DOWN INTO MTR CANAL. REACTOR IS FUELED AS AN ETR MOCK-UP. LIGHTS DANGLE BELOW WATER LEVEL. CONTROL RODS AND OTHER APPARATUS DESCEND FROM ABOVE WATER LEVEL. INL NEGATIVE NO. 56-900. Jack L. Anderson, Photographer, 3/26/1956 - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID

  9. Intraoperative implant rod three-dimensional geometry measured by dual camera system during scoliosis surgery.

    PubMed

    Salmingo, Remel Alingalan; Tadano, Shigeru; Abe, Yuichiro; Ito, Manabu

    2016-05-12

    Treatment for severe scoliosis is usually attained when the scoliotic spine is deformed and fixed by implant rods. Investigation of the intraoperative changes of implant rod shape in three-dimensions is necessary to understand the biomechanics of scoliosis correction, establish consensus of the treatment, and achieve the optimal outcome. The objective of this study was to measure the intraoperative three-dimensional geometry and deformation of implant rod during scoliosis corrective surgery.A pair of images was obtained intraoperatively by the dual camera system before rotation and after rotation of rods during scoliosis surgery. The three-dimensional implant rod geometry before implantation was measured directly by the surgeon and after surgery using a CT scanner. The images of rods were reconstructed in three-dimensions using quintic polynomial functions. The implant rod deformation was evaluated using the angle between the two three-dimensional tangent vectors measured at the ends of the implant rod.The implant rods at the concave side were significantly deformed during surgery. The highest rod deformation was found after the rotation of rods. The implant curvature regained after the surgical treatment.Careful intraoperative rod maneuver is important to achieve a safe clinical outcome because the intraoperative forces could be higher than the postoperative forces. Continuous scoliosis correction was observed as indicated by the regain of the implant rod curvature after surgery. PMID:27175467

  10. First OH reactivity measurements in Harvard Forest

    NASA Astrophysics Data System (ADS)

    Herdlinger-Blatt, I. S.; Martin, S. T.; Hansel, A.; McKinney, K. A.

    2013-12-01

    The OH reactivity provides critical insight into the HOx budget under actual atmospheric conditions, and has implications for the production of ozone and the formation of secondary organic material. Previous studies have indicated that the OH reactivity measured at field sites often exceeds model estimations, but current experiments remain inconclusive about the origin of the discrepancy between the modeled and measured OH reactivity (Lou et al., 2010). As of now there are only a limited number of atmospheric studies of total OH reactivity available, so to improve understanding of the OH reactivity more studies are needed. The first OH reactivity measurements in the northeastern United States are being performed during the summer of 2013 at Harvard Forest. Harvard forest, is located about 100 km west of the Boston metropolitan area, is one of the most intensively studied forests in North America. The main biogenic VOC emitted from Harvard Forest is isoprene followed by monoterpenes and methanol. Sampling for the OH reactivity measurements will be conducted from a 30m tall meteorological tower at the Harvard Forest site. The air is drawn into a reaction cell where the OH reactivity is determined using the Comparative Reactivity Method (Sinha et al., 2008) employing a High-Sensitivity Proton Transfer Reaction Mass Spectrometer (Lindinger et al., 1998, Hansel et al., 1998). In addition to the OH reactivity measurements, the most abundant compounds present in the air sample will be quantified using PTR-MS. The quantification of these compounds is needed to compare the theoretical calculated OH reactivity with the measured OH reactivity data. The measurements will be used to evaluate our understanding of the OH budget at Harvard Forest. References: A. Hansel, A. Jordan, C. Warneke, R. Holzinger, and W. Lindinger.: Improved Detection Limit of the Proton-transfer Reaction Mass Spectrometer: On-line Monitoring of Volatile Organic Compounds at Mixing Ratios of a Few PPTV

  11. Measurements of lightning rod responses to nearby strikes

    NASA Astrophysics Data System (ADS)

    Moore, C. B.; Aulich, G. D.; Rison, W.

    2000-05-01

    Following Benjamin Franklin's invention of the lightning rod, based on his discovery that electrified objects could be discharged by approaching them with a metal needle in hand, conventional lightning rods in the U.S. have had sharp tips. In recent years, the role of the sharp tip in causing a lightning rod to act as a strike receptor has been questioned leading to experiments in which pairs of various sharp-tipped and blunt rods have been exposed beneath thunderclouds to determine the better strike receptor. After seven years of tests, none of the sharp Franklin rods or of the so-called “early streamer emitters” has been struck, but 12 blunt rods with tip diameters ranging from 12.7 mm to 25.4 mm have taken strikes. Our field experiments and our analyses indicate that the strike-reception probabilities of Franklin's rods are greatly increased when their tips are made moderately blunt.

  12. Impact of the control rod consumption on the reactivity control of a SFR break-even core

    SciTech Connect

    Blanchet, D.; Fontaine, B.

    2012-07-01

    Current design studies on Sodium Fast Reactor (SFR) differ from those performed in the past by the fact that design criteria are now those of the Generation IV reactors. In order to improve their safety, reactors with break-even cores are preferred because they minimize the needs in terms of reactivity control and limit the consequences of control rod withdrawal. Furthermore, as the reactivity control needs are low, break-even core enables the use of absorbing materials with reduced efficiency (natural boron, hafnium...). Nevertheless, the use of control rods with few absorbing materials may present the disadvantage of a non-negligible ({approx}10%) loss of efficiency due to their consumption under irradiation. This paper presents a methodology to calculate accurately and analyze this consumption. (authors)

  13. Study of the automatic measuring technique and instrument for an automobile shock-absorber connecting rod

    NASA Astrophysics Data System (ADS)

    Chen, Chan-Yao; Dai, Shuguang; Zhang, R. J.; Mu, Ping-An

    1993-09-01

    The autinobile shock absorber connecting rod makes very strict tolerance requirements on the diameter size, roundness, straightness. Because it is a kind of thin and long workpiece, it is difficult to measure the errors of the roundness and axis straightness. Furthermore, it brings much difficulty to realize the highly efficient autinatic measurment as the connecting rod is mass produced. Therefore, there is not any kind of connecting rod automatic measuring instrument available in China. In this article, the authors put forword the methods and principles which can autiatically and efficiently measure the above-mentioned errors of the connecting rod and have designed a reliable and simple automatic measuring instrument, Furthermore, the designing requirements and methods of the software and the electrical system are also introduced. The problem of the automatic measurement of the automobile shock absorber connecting rod has been solved. and it not only guarantees the quality of the rod, but also provides the basis for technical analysis of the product.

  14. A Statistical Approach to Predict the Failure Enthalpy and Reliability of Irradiated PWR Fuel Rods During Reactivity-Initiated Accidents

    SciTech Connect

    Nam, Cheol; Jeong, Yong-Hwan; Jung, Youn-Ho

    2001-11-15

    During the last decade, the failure behavior of high-burnup fuel rods under a reactivity-initiated accident (RIA) condition has been a serious concern since fuel rod failures at low enthalpy have been observed. This has resulted in the reassessment of existing licensing criteria and failure-mode study. To address the issue, a statistics-based methodology is suggested to predict failure probability of irradiated fuel rods under an RIA. Based on RIA simulation results in the literature, a failure enthalpy correlation for an irradiated fuel rod is constructed as a function of oxide thickness, fuel burnup, and pulse width. Using the failure enthalpy correlation, a new concept of ''equivalent enthalpy'' is introduced to reflect the effects of the three primary factors as well as peak fuel enthalpy into a single damage parameter. Moreover, the failure distribution function with equivalent enthalpy is derived, applying a two-parameter Weibull statistical model. Finally, the sensitivity analysis is carried out to estimate the effects of burnup, corrosion, peak fuel enthalpy, pulse width, and cladding materials used.

  15. Measurement of reactive species for plasma medicine

    NASA Astrophysics Data System (ADS)

    Ono, Ryo

    2015-09-01

    Plasma medicine has been intensively studied over the last decade. Reactive oxygen and nitrogen species are responsible for the therapeutic effects in plasma medicine. To examine the therapeutic effects of reactive species, the densities of OH, O, and NO were measured using laser-induced fluorescence (LIF). A helium atmospheric-pressure plasma jet (10 kV, 10 kHz of 40 μs pulses) and a nanosecond streamer discharge (24 kV, 8 ns, 30 Hz) were utilized to treat mouse melanoma cells in a culture medium. Correlation between the dose of reactive species and deactivation rate of melanoma cells was measured with the aid of LIF. The results showed that the rate of cell death correlates with OH density, but not with O and NO densities. Next, a method to supply a specific reactive species to living organisms was developed. It utilizes photolysis of helium-buffered H2O and O2 by vacuum ultraviolet (VUV) light to produce reactive species. The VUV method was utilized to sterilize Bacillus atrophaeus on agar plate. With the VUV method, it was succeeded to show sterilization only by OH radicals. A 30 s treatment with approximately 0.1 ppm OH radicals caused visible sterilization.

  16. Validation of a Brief Measure of Opioid Dependence: The Rapid Opioid Dependence Screen (RODS)

    PubMed Central

    Wickersham, Jeffrey A.; Azar, Marwan M.; Cannon, Christopher M.; Altice, Frederick L.; Springer, Sandra A.

    2015-01-01

    The Rapid Opioid Dependence Screen (RODS) is an 8-item measure of opioid dependence designed for quick, targeted screening in clinical and research settings. Based on the Diagnostic and Statistical Manual of Mental Disorders, Fourth edition, criteria, the RODS has an average administration of less than 2 minutes and can easily be administered as a stand-alone instrument or as part of a comprehensive interview. This study reports on the initial validation of the RODS among a sample of 97 newly incarcerated, HIV-positive individuals. Using the Mini International Neuropsychiatric Interview as the primary measure of opioid dependence, the RODS showed good-to-strong sensitivity (.97), specificity (.76), positive predictive value (.69), and negative predictive value (.98), while concordance analysis revealed moderate diagnostic agreement (κ = .67). Psychometric properties revealed strong internal consistency (α = .92) and inter-item correlations (.66 to .87). PMID:25559628

  17. Accurate measurement of residual stress in glass rod by photoelastic experiment

    SciTech Connect

    Baek, Tae Hyun; Lee, Jae Choon; Kim, Dong Hyun

    1996-12-31

    Photoelastic law is used to measure residual stresses in glass rods which have been heat-treated at different temperatures ranging from 560{degrees}C to 665 {degrees}C. This research is performed to analyze the variation of residual stresses with respect to heat-treatment temperatures of glass rods. In order to measure the stresses accurately, both fringe sharpening and fringe multiplication techniques are applied to the determination of photoelastic fringe orders. The experimental results show that all the hoop stress components are changed from tensile stresses to compressive ones at approximate R/R{sub o}=0.6, where R is any measured radius and R{sub o} outer radius. For the borosilicate glass rods which are used in this experiment, residual stresses increase as heat-treatment temperatures are raised from 560{degrees}C to 665{degrees}C. These experimental results are compared with ones calculated by Instant Freezing Numerical Model.

  18. Smartphones as experimental tools to measure acoustical and mechanical properties of vibrating rods

    NASA Astrophysics Data System (ADS)

    González, Manuel Á.; González, Miguel Á.

    2016-07-01

    Modern smartphones have calculation and sensor capabilities that make them suitable for use as versatile and reliable measurement devices in simple teaching experiments. In this work a smartphone is used, together with low cost materials, in an experiment to measure the frequencies emitted by vibrating rods of different materials, shapes and lengths. The results obtained with the smartphone have been compared with theoretical calculations and the agreement is good. Alternatively, physics students can perform the experiment described here and use their results to determine the dependencies of the obtained frequencies on the rod characteristics. In this way they will also practice research methods that they will probably use in their professional life.

  19. Rod examination gauge

    SciTech Connect

    Bacvinskas, W.S.; Bayer, J.E.; Davis, W.W.; Fodor, G.; Kikta, T.J.; Matchett, R.L.; Nilsen, R.J.; Wilczynski, R.

    1991-12-31

    The present invention is directed to a semi-automatic rod examination gauge for performing a large number of exacting measurements on radioactive fuel rods. The rod examination gauge performs various measurements underwater with remote controlled machinery of high reliability. The rod examination gauge includes instruments and a closed circuit television camera for measuring fuel rod length, free hanging bow measurement, diameter measurement, oxide thickness measurement, cladding defect examination, rod ovality measurement, wear mark depth and volume measurement, as well as visual examination. A control system is provided including a programmable logic controller and a computer for providing a programmed sequence of operations for the rod examination and collection of data.

  20. OH reactivity measurements within a boreal forest: evidence for unknown reactive emissions.

    PubMed

    Sinha, Vinayak; Williams, J; Lelieveld, J; Ruuskanen, T M; Kajos, M K; Patokoski, J; Hellen, H; Hakola, H; Mogensen, D; Boy, M; Rinne, J; Kulmala, M

    2010-09-01

    Boreal forests emit large amounts of volatile organic compounds (VOCs) which react with the hydroxyl radical (OH) to influence regional ozone levels and form secondary organic aerosol. Using OH reactivity measurements within a boreal forest in Finland, we investigated the budget of reactive VOCs. OH reactivity was measured using the comparative reactivity method, whereas 30 individual VOCs were measured using proton transfer reaction mass spectrometry, thermal-desorption gas chromatography mass spectrometry, and liquid chromatography mass spectrometry, in August 2008. The measured OH reactivity ranged from below detection limit (3.5 s(-1)), to approximately 60 s(-1) in a single pollution event. The average OH reactivity was approximately 9 s(-1) and no diel variation was observed in the profiles. The measured OH sinks (approximately 30 species) accounted for only 50% of the total measured OH reactivity, implying unknown reactive VOCs within the forest. The five highest measured OH sinks were: monoterpenes (1 s(-1)), CO (0.7 s(-1)), isoprene (0.5 s(-1)), propanal and acetone (0.3 s(-1)), and methane (0.3 s(-1)). We suggest that models be constrained by direct OH reactivity measurements to accurately assess the impact of boreal forest emissions on regional atmospheric chemistry and climate. PMID:20687598

  1. Measurement of rod seal lubrication for Stirling engine

    NASA Technical Reports Server (NTRS)

    Krauter, A. I.

    1980-01-01

    The elastohydrodynamic behavior of sliding elastomeric seals for the Stirling engine, was analyzed using an experimental apparatus to determine the instantaneous oil film thickness throughout the cyclic reciprocating motion. Tests were conducted on two commercial elastomeric seals: a "T" seal (76 mm O.D. and 3.8 mm between backing rings) and an "O" ring (76 mm O.D. and 5.3 mm diameter). Testing conditions included seal durometers of 70 and 90, sliding velocities of 0.8, 2.0, and 3.6 m/s, and no pressure gradient across the seal. Both acrylic and aluminum cylinders were used. Measured oil film thickness profiles were compared to results of the elastohydrodynamic analysis. The comparison shows an overall qualitative agreement. Friction and oil leakage measurements were also made at these sliding speeds. The fluid used was a typical synthetic base automotive lubricant. It is concluded that this first time experimental analytical comparison for oil film thickness indicates the need for some improvements in the analytical model and in the experimental technique.

  2. Measurement of VOC reactivities using a photochemical flow reactor

    SciTech Connect

    Hurley, M.D.; Chang, T.Y.; Japar, S.M.; Wallington, T.J.

    1998-07-01

    A commercial ambient air monitoring instrument, the Airtrak 2000, has been modified for use as a photochemical flow reactor and used to measure the absolute and incremental reactivity of 18 single test VOCs and the incremental reactivity of six multicomponent VOC mixtures. A flow technique is a useful supplement to traditional static chamber experiments. The static chamber technique involves periodic sampling of an irradiated mixture in a photochemical chamber. Under these conditions, the irradiated mixture is always in transition. Using a flow system, a steady-state condition is established within the flow reactor that is representative, in this case, of the early stages of the smog forming process in the atmosphere. The measurement technique also allows changes in the background chamber reactivity to be monitored and taken into account. The incremental reactivity of 13 of the 18 test compounds measured is compared with previously reported results from a static chamber experiment, and the two data sets are generally in good agreement. The additivity of reactivity was tested by measuring the incremental reactivity of six multicomponent mixtures, the components being compounds measured individually in this study. The measured reactivity of a mixture was compared to that calculated from the sum of the measured reactivity of the mixture`s individual components. The results show that reactivity is additive for the concentration range studied.

  3. Factors influencing helium measurements for detection of control rod failures in BWR

    SciTech Connect

    Larsson, I.; Sihver, L.; Loner, H.; Ledergerber, G.; Schnurr, B.

    2012-07-01

    Much effort has been made to minimize the number and consequences of fuel failures at nuclear power plants. The consequences of control rod failures have also gained an increased attention. In this paper we introduce a system for on-line surveillance of control rod integrity which has several advantages comparing to the surveillance methods available today in boiling water reactors (BWRs). This system measures the helium released from failed control rods containing boron carbide (B4C). However, there are a number of factors that might influence measurements, which have to be taken into consideration when evaluating the measured data. These factors can be separated into two groups: 1) local adjustments, made on the sampling line connecting the detector to the off-gas system, and 2) plant operational parameters. The adjustments of the sample line conditions include variation of gas flow rate and gas pressure in the line. Plant operational factors that may influence helium measurements can vary from plant to plant. The factors studied at Leibstadt nuclear power plant (KKL) were helium impurities in injected hydrogen gas, variation of the total off-gas flow and regular water refill. In this paper we discuss these factors and their significance and present experimental results of measurements at KKL. (authors)

  4. Electromagnetic methods for measuring materials properties of cylindrical rods and array probes for rapid flaw inspection

    SciTech Connect

    Sun, Haiyan

    2005-05-01

    The case-hardening process modifies the near-surface permeability and conductivity of steel, as can be observed through changes in alternating current potential drop (ACPD) along a rod. In order to evaluate case depth of case hardened steel rods, analytical expressions are derived for the alternating current potential drop on the surface of a homogeneous rod, a two-layered and a three-layered rod. The case-hardened rod is first modeled by a two-layer rod that has a homogeneous substrate with a single, uniformly thick, homogeneous surface layer, in which the conductivity and permeability values differ from those in the substrate. By fitting model results to multi-frequency ACPD experimental data, estimates of conductivity, permeability and case depth are found. Although the estimated case depth by the two-layer model is in reasonable agreement with the effective case depth from the hardness profile, it is consistently higher than the effective case depth. This led to the development of the three-layer model. It is anticipated that the new three-layered model will improve the results and thus makes the ACPD method a novel technique in nondestructive measurement of case depth. Another way to evaluate case depth of a case hardened steel rod is to use induction coils. Integral form solutions for an infinite rod encircled by a coaxial coil are well known, but for a finite length conductor, additional boundary conditions must be satisfied at the ends. In this work, calculations of eddy currents are performed for a two-layer conducting rod of finite length excited by a coaxial circular coil carrying an alternating current. The solution is found using the truncated region eigenfunction expansion (TREE) method. By truncating the solution region to a finite length in the axial direction, the magnetic vector potential can be expressed as a series expansion of orthogonal eigenfunctions instead of as a Fourier integral. Closed-form expressions are derived for the electromagnetic

  5. Measurement of oil film thickness for application to elastomeric Stirling engine rod seals

    NASA Technical Reports Server (NTRS)

    Krauter, A. I.

    1981-01-01

    The rod seal in the Stirling engine has the function of separating high pressure gas from low or ambient pressure oil. An experimental apparatus was designed to measure the oil film thickness distribution for an elastomeric seal in a reciprocating application. Tests were conducted on commercial elastomeric seals having a 76 mm rod and a 3.8 mm axial width. Test conditions included 70 and 90 seal durometers, a sliding velocity of 0.8 m/sec, and a zero pressure gradient across the seal. An acrylic cylinder and a typical synthetic base automotive lubricant were used. The experimental results showed that the effect of seal hardness on the oil film thickness is considerable. A comparison between analytical and experimental oil film profiles for an elastomeric seal during relatively high speed reciprocating motion showed an overall qualitative agreement.

  6. Modeling smog chamber measurements of vehicle exhaust VOC reactivities

    SciTech Connect

    Chang, T.Y.; Nance, B.I.; Kelly, N.A.

    1997-12-31

    Vehicle exhaust VOC reactivities, measured at GM`s smog chamber facility, have been modeled using the SAPRC93 photochemical mechanism. The vehicle exhaust mixtures were generated by a single vehicle run over a portion of the Federal Test Procedure using three Auto/Oil reformulated test gasolines. For each run, up to 156 individual VOC species were identified. Initial HONO concentrations are needed to simulate reactivity measurement runs. (HONO is expected to be generated in a Tedlar bag holding the exhaust sample prior to its transfer to the smog chambers.) Measured and simulated relative incremental reactivities for the three exhaust mixtures are highly consistent. However, measured relative incremental reactivities are more sensitive to fuel effects than simulated ones. The maximum incremental reactivity (MIR)-based relative incremental reactivities, derived from individual species concentrations and MIR factors, are very close to simulated ones. A number of sensitivity simulation runs have been carried out to investigate the impact of HONO and other variables. Results show that relative reactivities of actual vehicle exhaust emissions can be measured by chamber runs in spite of the HONO effect.

  7. Analysis of MERCI decay heat measurement for PWR UO{sub 2} fuel rod

    SciTech Connect

    Jaboulay, J.C.; Bourganel, S.

    2012-01-15

    Decay heat measurements, called the MERCI experiment, were conducted at Commissariat a l'Energie Atomique (CEA)/Saclay to characterize accurately residual power at short cooling time and verify its prediction by decay code and nuclear data. The MOSAIC calorimeter, developed and patented by CEA/Grenoble (DTN/SE2T), enables measurement of the decay heat released by a pressurized water reactor (PWR) fuel rod sample between 200 and 4 W within a precision of 1%. The MERCI experiment included three phases. At first, a UO{sub 2} fuel rod sample was irradiated in the CEA/Saclay experimental reactor OSIRIS. The burnup achieved at the end of irradiation was similar to 3.5 GWd/tonne. The second phase was the transfer of the fuel rod sample from its irradiation location to a hot cell, to be inserted inside the MOSAIC calorimeter. It took 26 min to carry out the transfer. Finally, decay heat released by the PWR sample was measured from 27 min to 42 days after shutdown. Post irradiation examinations were performed to measure concentrations of some heavy nuclei (U, Pu) and fission products (Cs, Nd). The decay heat was predicted using a calculation scheme based on the PEPIN2 depletion code, the TRIPOLI-4 Monte Carlo code, and the JEFF3.1.1 nuclear data file. The MERCI experiment analysis shows that the discrepancy between the calculated and the experimental decay heat values is included between -10% at 27 min and +6% at 12 h, 30 min otter shutdown. From 4 up to 42 days of cooling time, the difference between calculation and measurement is about ± 1%, i.e., experimental uncertainty. The MERCI experiment represents a significant contribution for code validation; the time range above 10{sup 5} s has not been validated previously. (authors)

  8. The reactivity worth of protactinium-233 inferred from measurements

    SciTech Connect

    Freeman, L.B.; Hecker, H.C.

    1982-02-01

    In a thorium-fueled reactor, the conversion of /sup 232/Th to /sup 233/U involves the intermediate nuclide /sup 233/Pa. This isotope has a significant reactivity effect in any thorium reactor, especially one with an important epithermal flux component. The light water breeder reactor, operating in the Shippingport atomic power station, is a /sup 233/U-Th reactor with about half the power produced at energies above thermal. The reactivity effect of full-power equilibrium /sup 233/Pa has been inferred from critical position measurements and control element reactivity worths to be approximately 2.5% delta rho in this reactor, confirming calculational predictions.

  9. Rodding Surgery

    MedlinePlus

    ... Rods can be made of stainless steel or titanium. Regular rods do not expand. They have many ... v regular), the rod materials (stainless steel v titanium) and the age for a first rodding surgery. ...

  10. Development of reactivity feedback effect measurement techniques under sub-critical condition in fast reactors

    SciTech Connect

    Kitano, A.; Nishi, H.; Suzuki, T.; Okajima, S.; Kanemoto, S.

    2012-07-01

    The first-of-a-kind reactor has been licensed by a safety examination of the plant design based on the measured data in precedent mock-up experiments. The validity of the safety design can be confirmed without a mock-up experiment, if the reactor feed-back characteristics can be measured before operation, with the constructed reactor itself. The 'Synthesis Method', a systematic and sophisticated method of sub-criticality measurement, is proposed in this work to ensure the safety margin before operation. The 'Synthesis Method' is based on the modified source multiplication method (MSM) combined with the noise analysis method to measure the reference sub-criticality level for MSM. A numerical simulation for the control-rod reactivity worth and the isothermal feed-back reactivity was conducted for typical fast reactors of 100 MWe-size, 300 MWe-size, 750 MWe-size, and 1500 MWe-size to investigate the applicability of Synthesis Method. The number of neutron detectors and their positions necessary for the measurement were investigated for both methods of MSM and the noise analysis by a series of parametric survey calculations. As a result, it was suggested that a neutron detector located above the core center and three or more neutron detectors located above the radial blanket region enable the measurement of sub-criticality within 10% uncertainty from -$0.5 to -$2 and within 15% uncertainty for the deeper sub-criticality. (authors)

  11. Kinetic Approaches to Measuring Peroxiredoxin Reactivity

    PubMed Central

    Winterbourn, Christine C.; Peskin, Alexander V.

    2016-01-01

    Peroxiredoxins are ubiquitous thiol proteins that catalyse the breakdown of peroxides and regulate redox activity in the cell. Kinetic analysis of their reactions is required in order to identify substrate preferences, to understand how molecular structure affects activity and to establish their physiological functions. Various approaches can be taken, including the measurement of rates of individual steps in the reaction pathway by stopped flow or competitive kinetics, classical enzymatic analysis and measurement of peroxidase activity. Each methodology has its strengths and they can often give complementary information. However, it is important to understand the experimental conditions of the assay so as to interpret correctly what parameter is being measured. This brief review discusses different kinetic approaches and the information that can be obtained from them. PMID:26813658

  12. Method and apparatus for measuring reactivity of fissile material

    DOEpatents

    Lee, D.M.; Lindquist, L.O.

    1982-09-07

    Given are a method and apparatus for measuring nondestructively and noninvasively (i.e., using no internal probing) the burnup, reactivity, or fissile content of any material which emits neutrons and which has fissionable components. The assay is accomplished by altering the return flux of neutrons into the fuel assembly by means of changing the reflecting material. The existing passive neutron emissions in the material being assayed are used as the source of interrogating neutrons. Two measurements of either emitted neutron or emitted gamma-ray count rates are made and are then correlated to either reactivity, burnup, or fissionable content of the material being assayed, thus providing a measurement of either reactivity, burnup, or fissionable content of the material being assayed. Spent fuel which has been freshly discharged from a reactor can be assayed using this method and apparatus. Precisions of 1000 MWd/tU appear to be feasible.

  13. Nighttime reactive nitrogen measurements from stratospheric infrared thermal emission observations

    NASA Technical Reports Server (NTRS)

    Abbas, Mian M.; Kunde, Virgil G.; Brasunas, J. C.; Herman, J. R.; Massie, Steven T.

    1991-01-01

    IR thermal emission spectra of the earth's atmosphere in the 700-2000/cm region were obtained with a cryogenically cooled high-resolution interferometer spectrometer on a balloon flight from Palestine, Texas, on September 15-16, 1986. The observations exhibit spectral features of a number of stratospheric constituents, including important species of the reactive nitrogen family. An analysis of the observed data for simultaneously measured vertical distributions of O3, H2O, N2O, NO2, N2O5, HNO3, and ClONO2 is presented. These measurements permit the first direct determination of the nighttime total reactive nitrogen concentrations, and the partitioning of the important elements of the NO(x) family. Comparisons of the total reactive nitrogen budget are made with the measurements by the ATMOS experiment and with the predictions of one-dimensional and two-dimensional photochemical models.

  14. Structure Model Index Does Not Measure Rods and Plates in Trabecular Bone

    PubMed Central

    Salmon, Phil L.; Ohlsson, Claes; Shefelbine, Sandra J.; Doube, Michael

    2015-01-01

    Structure model index (SMI) is widely used to measure rods and plates in trabecular bone. It exploits the change in surface curvature that occurs as a structure varies from spherical (SMI = 4), to cylindrical (SMI = 3) to planar (SMI = 0). The most important assumption underlying SMI is that the entire bone surface is convex and that the curvature differential is positive at all points on the surface. The intricate connections within the trabecular continuum suggest that a high proportion of the surface could be concave, violating the assumption of convexity and producing regions of negative differential. We implemented SMI in the BoneJ plugin and included the ability to measure the amounts of surface that increased or decreased in area after surface mesh dilation, and the ability to visualize concave and convex regions. We measured SMI and its positive (SMI+) and negative (SMI−) components, bone volume fraction (BV/TV), the fraction of the surface that is concave (CF), and mean ellipsoid factor (EF) in trabecular bone using 38 X-ray microtomography (XMT) images from a rat ovariectomy model of sex steroid rescue of bone loss, and 169 XMT images from a broad selection of 87 species’ femora (mammals, birds, and a crocodile). We simulated bone resorption by eroding an image of elephant trabeculae and recording SMI and BV/TV at each erosion step. Up to 70%, and rarely <20%, of the trabecular surface is concave (CF 0.155–0.700). SMI is unavoidably influenced by aberrations induced by SMI−, which is strongly correlated with BV/TV and CF. The plate-to-rod transition in bone loss is an erroneous observation resulting from the close and artifactual relationship between SMI and BV/TV. SMI cannot discern between the distinctive trabecular geometries typical of mammalian and avian bone, whereas EF clearly detects birds’ more plate-like trabeculae. EF is free from confounding relationships with BV/TV and CF. SMI results reported in the literature should be

  15. Structure Model Index Does Not Measure Rods and Plates in Trabecular Bone.

    PubMed

    Salmon, Phil L; Ohlsson, Claes; Shefelbine, Sandra J; Doube, Michael

    2015-01-01

    Structure model index (SMI) is widely used to measure rods and plates in trabecular bone. It exploits the change in surface curvature that occurs as a structure varies from spherical (SMI = 4), to cylindrical (SMI = 3) to planar (SMI = 0). The most important assumption underlying SMI is that the entire bone surface is convex and that the curvature differential is positive at all points on the surface. The intricate connections within the trabecular continuum suggest that a high proportion of the surface could be concave, violating the assumption of convexity and producing regions of negative differential. We implemented SMI in the BoneJ plugin and included the ability to measure the amounts of surface that increased or decreased in area after surface mesh dilation, and the ability to visualize concave and convex regions. We measured SMI and its positive (SMI(+)) and negative (SMI(-)) components, bone volume fraction (BV/TV), the fraction of the surface that is concave (CF), and mean ellipsoid factor (EF) in trabecular bone using 38 X-ray microtomography (XMT) images from a rat ovariectomy model of sex steroid rescue of bone loss, and 169 XMT images from a broad selection of 87 species' femora (mammals, birds, and a crocodile). We simulated bone resorption by eroding an image of elephant trabecule and recording SMI and BV/TV at each erosion step. Up to 70%, and rarely <20%, of the trabecular surface is concave (CF 0.155-0.700). SMI is unavoidably influenced by aberrations induced by SMI(-), which is strongly correlated with BV/TV and CF. The plate-to-rod transition in bone loss is an erroneous observation resulting from the close and artifactual relationship between SMI and BV/TV. SMI cannot discern between the distinctive trabecular geometries typical of mammalian and avian bone, whereas EF clearly detects birds' more plate-like trabecule. EF is free from confounding relationships with BV/TV and CF. SMI results reported in the literature should be

  16. Method and apparatus for measuring reactivity of fissile material

    DOEpatents

    Lee, David M.; Lindquist, Lloyd O.

    1985-01-01

    Given are a method and apparatus for measuring nondestructively and non-invasively (i.e., using no internal probing) the burnup, reactivity, or fissile content of any material which emits neutrons and which has fissionable components. No external neutron-emitting interrogation source or fissile material is used and no scanning is required, although if a profile is desired scanning can be used. As in active assays, here both reactivity and content of fissionable material can be measured. The assay is accomplished by altering the return flux of neutrons into the fuel assembly. The return flux is altered by changing the reflecting material. The existing passive neutron emissions in the material being assayed are used as the source of interrogating neutrons. Two measurements of either emitted neutron or emitted gamma-ray count rates are made and are then correlated to either reactivity, burnup, or fissionable content of the material being assayed, thus providing a measurement of either reactivity, burnup, or fissionable content of the material being assayed. Spent fuel which has been freshly discharged from a reactor can be assayed using this method and apparatus. Precisions of 1000 MWd/tU appear to be feasible.

  17. REACTIVITY MEASUREMENT FACILITY, UNDER CONSTRUCTION OVER MTR CANAL IN BASEMENT ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    REACTIVITY MEASUREMENT FACILITY, UNDER CONSTRUCTION OVER MTR CANAL IN BASEMENT OF MTR BUILDING, TRA-603. WOOD PLANKS REST ON CANAL WALL OBSERVABLE IN FOREGROUND. INL NEGATIVE NO. 11745. Unknown Photographer, 8/20/1954 - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID

  18. Measuring and monitoring KIPT Neutron Source Facility Reactivity

    SciTech Connect

    Cao, Yan; Gohar, Yousry; Zhong, Zhaopeng

    2015-08-01

    Argonne National Laboratory (ANL) of USA and Kharkov Institute of Physics and Technology (KIPT) of Ukraine have been collaborating on developing and constructing a neutron source facility at Kharkov, Ukraine. The facility consists of an accelerator-driven subcritical system. The accelerator has a 100 kW electron beam using 100 MeV electrons. The subcritical assembly has keff less than 0.98. To ensure the safe operation of this neutron source facility, the reactivity of the subcritical core has to be accurately determined and continuously monitored. A technique which combines the area-ratio method and the flux-to-current ratio method is purposed to determine the reactivity of the KIPT subcritical assembly at various conditions. In particular, the area-ratio method can determine the absolute reactivity of the subcritical assembly in units of dollars by performing pulsed-neutron experiments. It provides reference reactivities for the flux-to-current ratio method to track and monitor the reactivity deviations from the reference state while the facility is at other operation modes. Monte Carlo simulations are performed to simulate both methods using the numerical model of the KIPT subcritical assembly. It is found that the reactivities obtained from both the area-ratio method and the flux-to-current ratio method are spatially dependent on the neutron detector locations and types. Numerical simulations also suggest optimal neutron detector locations to minimize the spatial effects in the flux-to-current ratio method. The spatial correction factors are calculated using Monte Carlo methods for both measuring methods at the selected neutron detector locations. Monte Carlo simulations are also performed to verify the accuracy of the flux-to-current ratio method in monitoring the reactivity swing during a fuel burnup cycle.

  19. Seebeck Coefficient Measurements on Micron-Size Single-Crystal Zinc Germanium Nitride Rods

    NASA Astrophysics Data System (ADS)

    Dyck, J. S.; Colvin, J. R.; Quayle, P. C.; Peshek, T. J.; Kash, K.

    2016-01-01

    II-IV-nitride compounds are tetrahedrally bonded, heterovalent ternary semiconductors that have recently garnered attention for their potential technological applications. These materials are derived from the parent III-nitride compounds; ZnGeN2 is the II-IV-nitride analogue to the III-nitride GaN. Very little is known about the transport properties of ZnGeN2. In this work, we present Seebeck coefficient (S) data on 3-micron-diameter, 70-micron-long, single-crystal ZnGeN2 rods, employing a novel measurement approach. The measurements of S show that the majority free carriers are electrons, and imply that the carrier gas is degenerate. Within a single-band model for the conduction band, a carrier concentration of order 1019 cm-3 was estimated for a measured S = -90 μV/K. Together with electrical transport measurements, a lower limit for the electron mobility is estimated to be ˜20 cm2/V-s. A discussion of this material as a thermoelectric is presented. The background level of free electrons in this unintentionally doped ZnGeN2 is very near the predicted optimum value for maximum thermoelectric performance.

  20. Seebeck Coefficient Measurements on Micron-Size Single-Crystal Zinc Germanium Nitride Rods

    NASA Astrophysics Data System (ADS)

    Dyck, J. S.; Colvin, J. R.; Quayle, P. C.; Peshek, T. J.; Kash, K.

    2016-06-01

    II-IV-nitride compounds are tetrahedrally bonded, heterovalent ternary semiconductors that have recently garnered attention for their potential technological applications. These materials are derived from the parent III-nitride compounds; ZnGeN2 is the II-IV-nitride analogue to the III-nitride GaN. Very little is known about the transport properties of ZnGeN2. In this work, we present Seebeck coefficient ( S) data on 3-micron-diameter, 70-micron-long, single-crystal ZnGeN2 rods, employing a novel measurement approach. The measurements of S show that the majority free carriers are electrons, and imply that the carrier gas is degenerate. Within a single-band model for the conduction band, a carrier concentration of order 1019 cm-3 was estimated for a measured S = -90 μV/K. Together with electrical transport measurements, a lower limit for the electron mobility is estimated to be ˜20 cm2/V-s. A discussion of this material as a thermoelectric is presented. The background level of free electrons in this unintentionally doped ZnGeN2 is very near the predicted optimum value for maximum thermoelectric performance.

  1. Fluorometer with a quartz-rod waveguide-integrating sphere configuration to measure evanescent-field luminescence

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A fluorometer was designed to measure evanescent-field luminescence. A quartz-rod waveguide (d = 2 mm) was installed coaxally inside a cylindrical flow-through cell (id = 2.3 mm, od = 6.3 mm, l = 116 mm). An excitation beam from a UV LED or a miniature xenon flashlamp was focused by a ball lens and ...

  2. Distance measurements near the myosin head-rod junction using fluorescence spectroscopy.

    PubMed Central

    Kekic, M; Huang, W; Moens, P D; Hambly, B D; dos Remedios, C G

    1996-01-01

    We reacted a fluorescent probe, N-methyl-2-anilino-6-naphthalenesulfonyl chloride (MNS-Ci), with a specific lysine residue of porcine cardiac myosin located in the S-2 region of myosin. We performed fluorescence resonance energy transfer (FRET) spectroscopy measurements between this site and three loci (Cys109, Cys125, and Cys154) located within different myosin light-chain 2s (LC2) bound to the myosin "head". We used LC2s from rabbit skeletal muscle myosin (Cys125), chicken gizzard smooth muscle myosin (Cys109), or a genetically engineered mutant of chicken skeletal muscle myosin (Cys154). The atomic coordinates of these LC2 loci can be closely approximated, and the FRET measurements were used to determine the position of the MNS-labeled lysine with respect to the myosin head. The C-terminus of myosin subfragment-1 determined by Rayment et al. ends abruptly after a sharp turn of its predominantly alpha-helical structure. We have constructed a model based on our FRET distance data combined with the known structure of chicken skeletal muscle myosin subfragment-1. This model suggests that the loci that bracket the head-rod junction will be useful for evaluating dynamic changes in this region. Images FIGURE 4 FIGURE 5 PMID:8804587

  3. Spectral sensitivity measurements reveal partial success in restoring missing rod function with gene therapy.

    PubMed

    Ripamonti, Caterina; Henning, G Bruce; Robbie, Scott J; Sundaram, Venki; van den Born, L Ingeborgh; Casteels, Ingele; de Ravel, Thomy J L; Moore, Anthony T; Smith, Alexander J; Bainbridge, James W; Ali, Robin R; Stockman, Andrew

    2015-01-01

    Restored rod visual function after gene therapy can be established unequivocally by demonstrating that, after dark adaptation, spectral sensitivity has the shape characteristic of rods and that this shape collapses to a cone-like shape before rods have recovered after an intense bleach. We used these tests to assess retinal function in eight young adults and children with early-onset severe retinal dystrophy from Phase II of a clinical gene-therapy trial for RPE65 deficiency that involved the subretinal delivery of a recombinant adeno-associated viral vector carrying RPE65. We found substantial improvements in rod sensitivity in two participants: dark-adapted spectral sensitivity was rod-like after treatment and was cone-like before rods had recovered after a bleach. After 40 min of dark adaptation, one participant showed up to 1,000-fold sensitivity improvements 4 months after treatment and the second up to 100-fold improvements 6 months after treatment. The dark-adapted spectral sensitivities of the other six participants remained cone-like and showed little improvement in sensitivity. PMID:26605849

  4. Measurements and modeling of reactive nitrogen deposition in southeast Brazil.

    PubMed

    Allen, A G; Machado, C M D; Cardoso, A A

    2011-05-01

    Increased reactive nitrogen (Nr) deposition due to expansion of agro-industry was investigated considering emission sources, atmospheric transport and chemical reactions. Measurements of the main inorganic nitrogen species (NO2, NH3, HNO3, and aerosol nitrate and ammonium) were made over a period of one year at six sites distributed across an area of ∼130,000 km2 in southeast Brazil. Oxidized species were estimated to account for ∼90% of dry deposited Nr, due to the region's large emissions of nitrogen oxides from biomass burning and road transport. NO2-N was important closer to urban areas, however overall HNO3-N represented the largest component of dry deposited Nr. A simple mathematical modeling procedure was developed to enable estimates of total Nr dry deposition to be made from knowledge of NO2 concentrations. The technique, whose accuracy here ranged from <1% to 29%, provides a useful new tool for the mapping of reactive nitrogen deposition. PMID:21354679

  5. Critical Configuration and Physics Measurements for Assemblies of U(93.15)O2 Fuel Rods (1.506-cm Pitch)

    SciTech Connect

    Margaret A. Marshall

    2013-03-01

    A series of critical experiments were completed from 1962–1965 at Oak Ridge National Laboratory’s (ORNL’s) Critical Experiments Facility (CEF) in support of the Medium-Power Reactor Experiments (MPRE) program. In the late 1950s, efforts were made to study “power plants for the production of electrical power in space vehicles.”(a) The MPRE program was a part of those efforts and studied the feasibility of a stainless-steel system, boiling potassium 1 MW(t), or about 140 kW(e), reactor. The program was carried out in [fiscal years] 1964, 1965, and 1966. A summary of the program’s effort was compiled in 1967.a The delayed critical experiments were a mockup of a small, potassium-cooled space power reactor for validation of reactor calculations and reactor physics methods. Initial experiments, performed in November and December of 1962, consisted of a core of unmoderated stainless-steel tubes, each containing 26 UO2 fuel pellets, surrounded by a graphite reflector. Measurements were performed to determine critical reflector arrangements, relative fission-rate distributions, and cadmium ratio distributions. Subsequent experiments used beryllium reflectors and also measured the reactivity for various materials placed in the core. “The [assemblies were built] on [a] vertical assembly machine so that the movable part was the core and bottom reflector” (see Reference 1). The experiment studied in this evaluation was the second of the series and had the fuel rods in a 1.506-cm-triangular pitch. One critical configuration was found (see Reference 3). Once the critical configuration had been achieved, various measurements of reactivity, relative axial and radial activation rates of 235U,bc and cadmium ratios were performed. The cadmium ratio, reactivity, and activation rate measurements performed on the critical configuration are described in Sections 1.3, 1.4, and 1.7, respectively.

  6. Critical Configuration and Physics Measurements for Assemblies of U(93.15)O2 Fuel Rods

    SciTech Connect

    Margaret A. Marshall

    2012-09-01

    A series of critical experiments were completed in 1962-1965 at Oak Ridge National Laboratory’s (ORNL’s) Critical Experiments Facility (CEF) in support of the Medium-Power Reactor Experiments (MPRE) program. In the late 1950s, efforts were made to study “power plants for the production of electrical power in space vehicles.”(a) The MPRE program was a part of those efforts and studied the feasibility of a stainless-steel system, boiling potassium 1 MW(t), or about 140 kW(e), reactor. The program was carried out in [fiscal years] 1964, 1965, and 1966. A summary of the program’s effort was compiled in 1967. The delayed critical experiments were a mockup of a small, potassium-cooled space power reactor for validation of reactor calculations and reactor physics methods. Initial experiments, performed in November and December of 1962, consisted of a core of unmoderated stainless-steel tubes, each containing 26 UO2 fuel pellets, surrounded by a graphite reflector. Measurements were made to determine critical reflector arrangements, fission-rate distributions, and cadmium ratio distributions. Subsequent experiments used beryllium reflectors and also measured the reactivity for various materials placed in the core. “The [assemblies were built] on [a] vertical assembly machine so that the movable part was the core and bottom reflector.”(Reference 1) The experiment studied in this evaluation was the first of the series and had the fuel tubes packed tightly into a 22.87 cm outside diameter (OD) core tank. Two critical configurations were found by varying the amount of graphite reflector (References 1 and 2). Once the critical configurations had been achieved, various measurements of reactivity, relative axial and radial activation rates of 235U, , and cadmium ratios were performed. The cadmium ratio, reactivity, and activation rate measurements performed on the critical configurations are described in Sections 1.3, 1.4 and 1.7, respectively. Information for this

  7. Critical Configuration and Physics Measurements for Assemblies of U(93.15)O2 Fuel Rods

    SciTech Connect

    Margaret A. Marshall

    2013-03-01

    A series of critical experiments were completed in 1962-1965 at Oak Ridge National Laboratory’s (ORNL’s) Critical Experiments Facility (CEF) in support of the Medium-Power Reactor Experiments (MPRE) program. In the late 1950s, efforts were made to study “power plants for the production of electrical power in space vehicles.”(a) The MPRE program was a part of those efforts and studied the feasibility of a stainless-steel system, boiling potassium 1 MW(t), or about 140 kW(e), reactor. The program was carried out in [fiscal years] 1964, 1965, and 1966. A summary of the program’s effort was compiled in 1967. The delayed critical experiments were a mockup of a small, potassium-cooled space power reactor for validation of reactor calculations and reactor physics methods. Initial experiments, performed in November and December of 1962, consisted of a core of unmoderated stainless-steel tubes, each containing 26 UO2 fuel pellets, surrounded by a graphite reflector. Measurements were made to determine critical reflector arrangements, fission-rate distributions, and cadmium ratio distributions. Subsequent experiments used beryllium reflectors and also measured the reactivity for various materials placed in the core. “The [assemblies were built] on [a] vertical assembly machine so that the movable part was the core and bottom reflector.”(Reference 1) The experiment studied in this evaluation was the first of the series and had the fuel tubes packed tightly into a 22.87 cm outside diameter (OD) core tank. Two critical configurations were found by varying the amount of graphite reflector (References 1 and 2). Once the critical configurations had been achieved, various measurements of reactivity, relative axial and radial activation rates of 235U, , and cadmium ratios were performed. The cadmium ratio, reactivity, and activation rate measurements performed on the critical configurations are described in Sections 1.3, 1.4 and 1.7, respectively. Information for this

  8. Measurements of the negative ion density in reactive gas plasmas

    NASA Astrophysics Data System (ADS)

    Shindo, Masako; Ueda, Yoko; Kawai, Yoshinobu; Ishii, Nobuo

    1999-11-01

    The reactive gas plasmas, such as C_4F_8, SiH4 and SF6 gas plasmas, have been widely used in plasma etching or CVD. The radicals and ions species in these plasmas have been reported in a lot of study. However, the negative ion density has not been measured quantitatively, since the conventional Langmuir probe cannot be used due to film depositions on its surface. In this study, the negative ion density in the reactive gas plasmas was measured with a heated Langmuir probe and an 8-mm microwave interferometer as a function of gas flow rate and radial position. Furthermore, the following equation was suggested to estimate the negative ion density only from the probe measurements: fracI_+(X )I_+(Ar) = [ fracI_-(X)I_-(Ar) + fracN_-(X )N_+(Ar)√fracT_e(X)T_e(Ar) ] √fracM_+(Ar)M_+(X), where N- denotes negative ion density and the other characteristics represent the conventional ones. The positive ion mass M+ should be assumed properly. It was confirmed that this equation provides the negative ion density both in the magnetized plasmas, such as ECR plasmas, and non-magnetized plasmas.

  9. Information and complexity measures in molecular reactivity studies.

    PubMed

    Welearegay, Meressa A; Balawender, Robert; Holas, Andrzej

    2014-07-28

    The analysis of the information and complexity measures as tools for the investigation of the chemical reactivity has been done in the spin-position and the position spaces, for the density and shape representations. The concept of the transferability and additivity of atoms or functional groups were used as "checkpoints" in the analysis of obtained results. The shape function as an argument of various measures reveals less information than the spinor density. Use of the shape function can yield wrong conclusions when the information measures such as the Shannon entropy (SE, S), the Fisher information (FI, I), the Onicescu information (OI, D), and complexities based on them are used for the systems with different electron numbers. Results obtained in the spinor-density representation show the transferability and additivity (while lacking in the case of the shape representation). The group transferability is well illustrated in the example of the X-Y molecules and their benzene derivatives. Another example is the methyl group transferability presented on the alkane-alkene-alkyne set. Analysis of the results displayed on planes between the three information-theoretical (IT) based measures has shown that the S-I plane provides "richer" information about the pattern, organization, similarity of used molecules than the I-D and D-S planes. The linear relation of high accuracy is noted between the kinetic energy and the FI and the OI measures. Another interesting regression was found between the atomization total energy and the atomization entropy. Unfortunately, the lack of the group electronic energy transferability indicates that no general relations between the IT measures and the chemical reactivity indices are observed. The molecular set chosen for the study includes different types of molecules with various functional groups (19 groups). The used set is large enough (more than 700 molecules) and diverse to improve the previous understating of molecular complexities

  10. Fuel Temperature Coefficient of Reactivity

    SciTech Connect

    Loewe, W.E.

    2001-07-31

    A method for measuring the fuel temperature coefficient of reactivity in a heterogeneous nuclear reactor is presented. The method, which is used during normal operation, requires that calibrated control rods be oscillated in a special way at a high reactor power level. The value of the fuel temperature coefficient of reactivity is found from the measured flux responses to these oscillations. Application of the method in a Savannah River reactor charged with natural uranium is discussed.

  11. Nuclear design of Helical Cruciform Fuel rods

    SciTech Connect

    Shirvan, K.; Kazimi, M. S.

    2012-07-01

    In order to increase the power density of current and new light water reactor designs, the Helical Cruciform Fuel (HCF) rods are proposed. The HCF rods are equivalent to a cylindrical rod, with the fuel in a cruciform shaped, twisted axially. The HCF rods increase the surface area to volume ratio and inter-subchannel mixing behavior due to their cruciform and helical shapes, respectively. In a previous study, the HCF rods have shown the potential to up-rate existing PWRs by 50% and BWRs by 25%. However, HCF rods do display different neutronics modeling and performance. The cruciform cross section of HCF rods creates radially asymmetric heat generation and temperature distribution. The nominal HCF rod's beginning of life reactivity is reduced, compared to a cylindrical rod with the same fuel volume, by 500 pcm, due to increase in absorption in cladding. The rotation of these rods accounts for reactivity changes, which depends on the H/HM ratio of the pin cell. The HCF geometry shows large sensitivities to U{sup 235} or gadolinium enrichments compared to a cylindrical geometry. In addition, the gadolinium-containing HCF rods show a stronger effect on neighboring HCF rods than in case of cylindrical rods, depending on the orientation of the HCF rods. The helical geometry of the rods introduces axial shadowing of about 600 pcm, not seen in typical cylindrical rods. (authors)

  12. Transient release kinetics of rod bipolar cells revealed by capacitance measurement of exocytosis from axon terminals in rat retinal slices.

    PubMed

    Oltedal, Leif; Hartveit, Espen

    2010-05-01

    Presynaptic transmitter release has mostly been studied through measurements of postsynaptic responses, but a few synapses offer direct access to the presynaptic terminal, thereby allowing capacitance measurements of exocytosis. For mammalian rod bipolar cells, synaptic transmission has been investigated in great detail by recording postsynaptic currents in AII amacrine cells. Presynaptic measurements of the dynamics of vesicular cycling have so far been limited to isolated rod bipolar cells in dissociated preparations. Here, we first used computer simulations of compartmental models of morphologically reconstructed rod bipolar cells to adapt the 'Sine + DC' technique for capacitance measurements of exocytosis at axon terminals of intact rod bipolar cells in retinal slices. In subsequent physiological recordings, voltage pulses that triggered presynaptic Ca(2+) influx evoked capacitance increases that were proportional to the pulse duration. With pulse durations 100 ms, the increase saturated at 10 fF, corresponding to the size of a readily releasable pool of vesicles. Pulse durations 400 ms evoked additional capacitance increases, probably reflecting recruitment from additional pools of vesicles. By using Ca(2+) tail current stimuli, we separated Ca(2+) influx from Ca(2+) channel activation kinetics, allowing us to estimate the intrinsic release kinetics of the readily releasable pool, yielding a time constant of 1.1 ms and a maximum release rate of 2-3 vesicles (release site)(1) ms(1). Following exocytosis, we observed endocytosis with time constants ranging from 0.7 to 17 s. Under physiological conditions, it is likely that release will be transient, with the kinetics limited by the activation kinetics of the voltage-gated Ca(2+) channels. PMID:20211976

  13. Measurement for both vibration and deformation of microsurface by Fizeau interferometer of composite self-focus rod sensor

    NASA Astrophysics Data System (ADS)

    Ming, Hai; Sun, Xiaohong; Bai, Ming; Liang, Zhongcheng; Zhang, Guoping; Li, Hui; Wu, Yunxia; Xie, Jiangping; Shu, Jizu

    1998-08-01

    By using composite self-focus rod, LD-pumped frequency doubling Nd:YVO4 laser and 3D fine regulation stand, a new Fizeau-type interferometer is developed. It can apply to measuring the micro-vibration and deformation of micro- surface at the same time. The theoretical analysis and the experimental results for the interferometer of self-focus sensor are given.

  14. Reactivity-adjusted VOC measurements by airtrack: A feasibility study

    SciTech Connect

    Chang, T.Y.; Hurley, M.D.; Nance, B.; Japar, S.M.

    1996-12-31

    Measurements of concentrations of ozone precursors, volatile organic compounds (VOC) and NO{sub x} (NO + NO{sub 2}), are essential to better understand ozone-precursor relationships in urban and regional areas. In the last two decades, major advances on measuring VOC and NO{sub x} have been made. Reliable techniques for measuring NO{sub x} are available currently, although it is difficult to measure NO{sub 2} without interferences of other species at routine monitoring sites. For VOC, reliable techniques are available for lighter nonmethane hydrocarbons (NMHC), and current techniques for measuring heavier NMHC and partially oxidized NMHC including carbonyl compounds are somewhat uncertain and are under further development. Currently available measurement techniques for VOC are time-consuming and expensive. Consequently, a simple measurement technique for reactivity-adjusted, total VOC would be valuable for evaluating ozone-precursor relationships. Recently, an integrated air quality assessment instrument, AIRTRAK, has been introduced. The uniqueness of the AIRTRAK is the possible, continuous measurements of ambient VOC. Measurements of smog formation coefficients and derivation of VOC concentrations are based on the integrated empirical rate (IER) model. However, the IER model does not appear to hold rigorously. Consequently, the capability of VOC measurements by AIRTRAK has not been demonstrated adequately. The purpose of the present paper is to investigate the VOC measurement capability of AIRTRAK after substantial experiences in flow-mode experiments using AIRTRAK at our laboratory. First, model simulations are performed to derive relationships between measured smog concentrations (by AIRTRAK) and ambient VOC concentrations. Using these relationships, numerical simulations are performed to simulate ambient VOC measurements. Further, preliminary investigations of implementing the present methodology to AIRTRAK are performed.

  15. Design of a compensated signal rod for low magnetic moment sample measurements with a vibrating sample magnetometer.

    PubMed

    Carignan, Louis-Philippe; Cochrane, Robert W; Ménard, David

    2008-03-01

    A zero-signal sample holder is proposed for the measurement of weak magnetic signals with vibrating sample magnetometers. With proper shape of the support rod, a nearly vanishing signal can be obtained as a function of the magnetic field and the temperature. In particular, it is shown that the addition of an extra part to a standard glass sample holder can reduce the diamagnetic signal by more than three orders of magnitude with no noise increase. The proposed method is applicable to field, temperature, and angular measurements; it is also ideally suited to direct measurement of nanometer thick magnetic layers deposited on much thicker diamagnetic substrates. PMID:18377045

  16. Spatial corrections for pulsed-neutron reactivity measurements.

    SciTech Connect

    Cao, Y.; Lee, J.; Nuclear Engineering Division; Univ. of Michigan

    2010-07-01

    For pulsed-neutron experiments performed in a subcritical reactor, the reactivity obtained from the area-ratio method is sensitive to detector positions. The spatial effects are induced by the presence of both the prompt neutron harmonics and the delayed neutron harmonics in the reactor. The traditional kinetics distortion factor is only limited to correcting the spatial effects caused by the fundamental prompt-{alpha} mode. In this paper, we derive spatial correction factors fp and fd to account for spatial effects induced by the prompt neutron harmonics and the delayed neutron harmonics, respectively. Our numerical simulations with the FX2-TH time-dependent multigroup diffusion code indicate that the high-order prompt neutron harmonics lead to significant spatial effects and cannot be neglected in calculating the spatial correction factors. The prompt spatial correction factor fp can be simply determined by the ratio of the normalized detector responses corresponding to the fundamental k-mode and the prompt neutron flux integrated over the pulse period. Thus, it is convenient to calculate and provides physically intuitive explanations on the spatial dependence of reactivity measured in the MUSE-4 experiments: overestimation of the subcriticality in regions close to the external neutron source and underestimation of the subcriticality away from the source but within the fuel region.

  17. Measurement of Fresh Fuel Rods to Demonstrate Compliance with Criticality Safety Limits

    SciTech Connect

    Miko, David K.; Desimone, David J.

    2015-11-03

    In order to operate TA-66 as a radiological facility with the quantity of nuclear material required to fulfil its mission, a criticality safety evaluation was required. This evaluation defined the control parameters for operations at the facility. The resulting evaluation for TA-66 placed limits on the amount of SNM, as well as other materials such as beryllium. In addition, there is a limit on the number of uranium fuel rods allowed subject to enrichment, outer diameter, and overall length restrictions. The enrichments for the rods to be shipped to TA-66 were documented in LA-UR-13-23581, but the outer diameter and length were not documented. This report provides this information.

  18. Atmospheric measurements of total OH reactivity: Intercomparison of the pump-probe technique and the comparative reactivity method

    NASA Astrophysics Data System (ADS)

    Dusanter, Sebastien; Hansen, Robert; Leonardis, Thierry; Schoemaecker, Coralie; Blocquet, Marion; Fittschen, Christa; Hanoune, Benjamin; Sinha, Vinayak; Stevens, Philip; Locoge, Nadine

    2013-04-01

    The hydroxyl radical (OH) drives the oxidation of organic trace gases that can lead to the production of ozone and secondary organic aerosols in the atmosphere. A complete understanding of the sources and sinks of OH is therefore important to address issues related to both air quality and climate change. However, recent measurements of total OH reactivity [1-2], which is the inverse of the OH lifetime, have pointed out that our understanding of OH sinks is still incomplete and important reactive trace gases have not yet been identified. These measurements of total OH reactivity are of particular interest since they provide a critical test of our understanding of the OH budget. Three techniques are available to measure the total OH reactivity, including the total OH loss rate method [3], the pump-probe method [4], and the comparative reactivity method (CRM) [5]. While the first two methods are based on direct measurements of OH decays using laser-induced fluorescence instruments, the CRM is based on a different approach in which a tracer molecule is detected instead of OH to determine the ambient OH loss rate. As these instruments were deployed in different field campaigns, intercomparison exercises would be useful to ensure the accuracy of the measurements. However, such intercomparisons have not yet been published. An informal intercomparison involving a CRM instrument from the Ecole des Mines de Douai (EMD) and a pump-probe instrument from the laboratory Physicochimie des Processus de Combustion et de l'Atmosphere (PC2A) took place in an urban environment at the university of Lille (France). The two OH reactivity instruments measured continuously side by side for a duration of two weeks. Collocated measurements of trace gases were also performed using O3, NOx and SO2 monitors, as well as two automated chromatographic instruments capable of measuring more than 50 volatile organic compounds (VOC). We will present cross calibrations of the two OH reactivity

  19. Differentiating challenge reactivity from psychomotor activity in studies of children's psychophysiology: considerations for theory and measurement.

    PubMed

    Bush, Nicole R; Alkon, Abbey; Obradović, Jelena; Stamperdahl, Juliet; Boyce, W Thomas

    2011-09-01

    Current methods of assessing children's physiological "stress reactivity" may be confounded by psychomotor activity, biasing estimates of the relation between reactivity and health. We examined the joint and independent contributions of psychomotor activity and challenge reactivity during a protocol for 5- and 6-year-old children (N = 338). Measures of parasympathetic reactivity (respiratory sinus arrhythmia [RSA]) and sympathetic reactivity (preejection period [PEP]) were calculated for social, cognitive, sensory, and emotional challenge tasks. Reactivity was calculated relative to both resting and a paired comparison task that accounted for psychomotor activity effects during each challenge. Results indicated that comparison tasks themselves elicited RSA and PEP responses, and reactivity adjusted for psychomotor activity was incongruent with reactivity calculated using rest. Findings demonstrate the importance of accounting for confounding psychomotor activity effects on physiological reactivity. PMID:21524757

  20. CHEMILUMINESCENCE MEASUREMENT OF REACTIVITY WEIGHTED ETHYLENE-EQUIVALENT HYDROCARBONS

    EPA Science Inventory

    A reactive hydrocarbon analyzer (RHA), based on the chemiluminescent reaction of hydrocarbons with oxygen atoms, is used to provide a rapid indication of reactivity weighted hydrocarbon mass in automobile exhaust. Samples are reported by their ethylene-equivalent concentration--t...

  1. A new fast neutron collar for safeguards inspection measurements of fresh low enriched uranium fuel assemblies containing burnable poison rods

    NASA Astrophysics Data System (ADS)

    Evans, Louise G.; Swinhoe, Martyn T.; Menlove, Howard O.; Schwalbach, Peter; Baere, Paul De; Browne, Michael C.

    2013-11-01

    Safeguards inspection measurements must be performed in a timely manner in order to detect the diversion of significant quantities of nuclear material. A shorter measurement time can increase the number of items that a nuclear safeguards inspector can reliably measure during a period of access to a nuclear facility. In turn, this improves the reliability of the acquired statistical sample, which is used to inform decisions regarding compliance. Safeguards inspection measurements should also maintain independence from facility operator declarations. Existing neutron collars employ thermal neutron interrogation for safeguards inspection measurements of fresh fuel assemblies. A new fast neutron collar has been developed for safeguards inspection measurements of fresh low-enriched uranium (LEU) fuel assemblies containing gadolinia (Gd2O3) burnable poison rods. The Euratom Fast Collar (EFC) was designed with high neutron detection efficiency to make a fast (Cd) mode measurement viable whilst meeting the high counting precision and short assay time requirements of the Euratom safeguards inspectorate. A fast mode measurement reduces the instrument sensitivity to burnable poison rod content and therefore reduces the applied poison correction, consequently reducing the dependence on the operator declaration of the poison content within an assembly. The EFC non-destructive assay (NDA) of typical modern European pressurized water reactor (PWR) fresh fuel assembly designs have been simulated using Monte Carlo N-particle extended transport code (MCNPX) simulations. Simulations predict that the EFC can achieve 2% relative statistical uncertainty on the doubles neutron counting rate for a fast mode measurement in an assay time of 600 s (10 min) with the available 241AmLi (α,n) interrogation source strength of 5.7×104 s-1. Furthermore, the calibration range of the new collar has been extended to verify 235U content in variable PWR fuel designs in the presence of up to 32

  2. Issues in Three-Dimensional Depletion Analysis of Measured Data Near the End of a Fuel Rod

    SciTech Connect

    DeHart, Mark D; Gauld, Ian C; Suyama, Kenya

    2008-01-01

    scarcity of experimental measurements for fuel taken from the end regions of a fuel rod. A number of 3-D depletion approaches based on Monte Carlo methods have been introduced in the past decade including, but not limited to, those listed in Refs. 5-7. A full listing would be quite extensive. Recent fuel-sample measurements from two discharged assemblies of the Takahama Unit 3 PWR provide data for fuel samples taken very close to the top of the active region of the fuel rod. This paper discusses results of TRITON-based 3-D depletion calculations completed in the analysis of the Takahama fuel samples.

  3. Reactivity measurement in estimation of benzoquinone and benzoquinone derivatives' allergenicity.

    PubMed

    Mbiya, Wilbes; Chipinda, Itai; Simoyi, Reuben H; Siegel, Paul D

    2016-01-01

    Benzoquinone (BQ) and benzoquinone derivatives (BQD) are used in the production of dyes and cosmetics. While BQ, an extreme skin sensitizer, is an electrophile known to covalently modify proteins via Michael Addition (MA) reaction whilst halogen substituted BQD undergo nucleophilic vinylic substitution (SNV) mechanism onto amine and thiol moieties on proteins, the allergenic effects of adding substituents on BQ have not been reported. The effects of inserting substituents on the BQ ring has not been studied in animal assays. However, mandated reduction/elimination of animals used in cosmetics testing in Europe has led to an increased need for alternatives for the prediction of skin sensitization potential. Electron withdrawing and electron donating substituents on BQ were assessed for effects on BQ reactivity toward nitrobenzene thiol (NBT). The NBT binding studies demonstrated that addition of EWG to BQ as exemplified by the chlorine substituted BQDs increased reactivity while addition of EDG as in the methyl substituted BQDs reduced reactivity. BQ and BQD skin allerginicity was evaluated in the murine local lymph node assay (LLNA). BQD with electron withdrawing groups had the highest chemical potency followed by unsubstituted BQ and the least potent were the BQD with electron donating groups. The BQD results demonstrate the impact of inductive effects on both BQ reactivity and allergenicity, and suggest the potential utility of chemical reactivity data for electrophilic allergen identification and potency ranking. PMID:26612505

  4. Measurement of OH reactivity by laser flash photolysis coupled with laser-induced fluorescence spectroscopy

    NASA Astrophysics Data System (ADS)

    Stone, Daniel; Whalley, Lisa K.; Ingham, Trevor; Edwards, Peter M.; Cryer, Danny R.; Brumby, Charlotte A.; Seakins, Paul W.; Heard, Dwayne E.

    2016-07-01

    OH reactivity (k'OH) is the total pseudo-first-order loss rate coefficient describing the removal of OH radicals to all sinks in the atmosphere, and is the inverse of the chemical lifetime of OH. Measurements of ambient OH reactivity can be used to discover the extent to which measured OH sinks contribute to the total OH loss rate. Thus, OH reactivity measurements enable determination of the comprehensiveness of measurements used in models to predict air quality and ozone production, and, in conjunction with measurements of OH radical concentrations, to assess our understanding of OH production rates. In this work, we describe the design and characterisation of an instrument to measure OH reactivity using laser flash photolysis coupled to laser-induced fluorescence (LFP-LIF) spectroscopy. The LFP-LIF technique produces OH radicals in isolation, and thus minimises potential interferences in OH reactivity measurements owing to the reaction of HO2 with NO which can occur if HO2 is co-produced with OH in the instrument. Capabilities of the instrument for ambient OH reactivity measurements are illustrated by data collected during field campaigns in London, UK, and York, UK. The instrumental limit of detection for k'OH was determined to be 1.0 s-1 for the campaign in London and 0.4 s-1 for the campaign in York. The precision, determined by laboratory experiment, is typically < 1 s-1 for most ambient measurements of OH reactivity. Total uncertainty in ambient measurements of OH reactivity is ˜ 6 %. We also present the coupling and characterisation of the LFP-LIF instrument to an atmospheric chamber for measurements of OH reactivity during simulated experiments, and provide suggestions for future improvements to OH reactivity LFP-LIF instruments.

  5. Reactivity of young chars via energetic distribution measurements

    SciTech Connect

    Calo, J.M.; Zhang, L.H.; Lu, W.; Lilly, W.D.

    1992-06-10

    We have developed what we believe to be the very first a priori prediction technique for the gasification reactivity of coal char. With this method the gasification reactivity of a coal char as function of temperature can be predicted from a single temperature programmed desorption (TPD) experiment following mild gasification at a single temperature (Calo et al., 1989; Hall and Calo, 1990a). This approach has been demonstrated for C0{sub 2} gasification of coal chars where the gasification reactivity is controlled by the thermal desorption of oxygen surface complexes formed during gasification. This approach may be extended to other oxidant species, such as steam, and carbon-hydrogen complexes for hydrogen gasification as well. In the current report, we present a summary of the work that has been conducted to date in constructing a new TGA/TPD-MS experimental system which provides us with the capability of simultaneous monitoring of transient sample mass data, as well as gas phase composition during thermal desorption experiments. In addition, we present some steam reactivity data obtained with another TGA (Cahn 113 system) which has been modified for steam gasification experiments.

  6. Total OH reactivity measurements at Manitou Experimental Forest in summer season during BEACHON-SRM08

    NASA Astrophysics Data System (ADS)

    Nakashima, Y.; Kato, S.; Kajii, Y.; Greenberg, J.; Karl, T.; Turnipseed, A.; Apel, E. C.; Guenther, A. B.; Harley, P. C.; Smith, J. N.

    2009-12-01

    The hydroxyl radical (OH) is well known to play a central role in initiating the oxidation of a number of atmospheric species. Measurement of total OH reactivity is important not only to understand mechanisms of oxidant formation in the troposphere but also to estimate the total amount of trace gas species, especially volatile organic compounds (VOCs). We have developed an OH reactivity measurement system using a laser pump probe technique. OH was artificially generated by the photolysis of ozone to produce O(1D) followed by reaction of O(1D) with water vapor. The lifetime of OH was then measured by a laser induced fluorescence technique. We measured OH reactivity at urban and suburban areas of Tokyo and confirmed the existence of unknown reactive species. The measurement of OH reactivity in rural areas where the effect of anthropogenic emissions is thought to be small is another essential test to ascertain the existence of unknown species and their oxidant formation potential. Total OH reactivity was measured at Manitou Experimental Forest (MEF) during August 8th-6thand 22th-28th, 2008. MEF is located in the southern part of the Rocky Mountains and about 80 km south from Denver. MEF is covered with ponderosa pine and observations indicate that the effect of anthropogenic emissions is small. The value of OH reactivity was about 5-10 s-1, smaller than that measured in urban or suburban areas of Tokyo. During the measurement period, a strong thunderstorm and tornado formed near MEF: this coincided with a rapid increase in OH reactivity. Sporadically high OH reactivity was also observed during some days due to transport of pollutants from the Front Range Urban Corridor. Together with the measurement of OH reactivity, traces species such as CO, NO, NOy, O3 and SO2 were analyzed. VOCs were analyzed by GC-FID and PTR-MS techniques. From the calculation of OH reactivity based on the analysis of traces species, about 60% of OH reactivity for VOCs came from biogenic VOCs

  7. Seasonal measurements of total OH reactivity emission rates from Norway spruce in 2011

    NASA Astrophysics Data System (ADS)

    Nölscher, A. C.; Bourtsoukidis, E.; Bonn, B.; Kesselmeier, J.; Lelieveld, J.; Williams, J.

    2013-06-01

    Numerous reactive volatile organic compounds (VOCs) are emitted into the atmosphere by vegetation. Most biogenic VOCs are highly reactive towards the atmosphere's most important oxidant, the hydroxyl (OH) radical. One way to investigate the chemical interplay between biosphere and atmosphere is through the measurement of total OH reactivity, the total loss rate of OH radicals. This study presents the first determination of total OH reactivity emission rates (measurements via the comparative reactivity method) based on a branch cuvette enclosure system mounted on a Norway spruce (Picea abies) throughout spring, summer and autumn 2011. In parallel VOC emission rates were monitored by a second proton-transfer-reaction mass spectrometer (PTR-MS), and total ozone (O3) loss rates were obtained inside the cuvette. Total OH reactivity emission rates were in general temperature and light dependent, showing strong diel cycles with highest values during daytime. Monoterpene emissions contributed most, accounting for 56-69% of the measured total OH reactivity flux in spring and early summer. However, during late summer and autumn the monoterpene contribution decreased to 11-16%. At this time, a large missing fraction of the total OH reactivity emission rate (70-84%) was found when compared to the VOC budget measured by PTR-MS. Total OH reactivity and missing total OH reactivity emission rates reached maximum values in late summer corresponding to the period of highest temperature. Total O3 loss rates within the closed cuvette showed similar diel profiles and comparable seasonality to the total OH reactivity fluxes. Total OH reactivity fluxes were also compared to emissions from needle storage pools predicted by a temperature-only-dependent algorithm. Deviations of total OH reactivity fluxes from the temperature-only-dependent emission algorithm were observed for occasions of mechanical and heat stress. While for mechanical stress, induced by strong wind, measured VOCs could

  8. Reactivity of young chars via energetic distribution measurements

    SciTech Connect

    Calo, J.M.; Lilly, W.D.

    1991-01-01

    The current project is directed at developing related techniques for the characterization and prediction/correlation of the reactivity of young'' chars to steam and oxygen. Of particular interest is mapping of the reactivity behavior of the resultant chars, as revealed by the energetic heterogeneity of the complexes with char preparation conditions; i.e., heating rate and ultimate temperature. In this first quarterly technical progress report we present the background of the project and the research program for the proposed investigations. The following work was accomplished on the experimental apparatus: a new set of electronics for the UTi quadrupole mass spectrometer head was purchased and delivered. The Temperature Programmed Desorption (TPD) System was moved to another laboratory and interfaced with the mass spectrometer system. A Polycold{trademark} freon refrigeration system was repaired and interfaced with the vacuum system for the TPD apparatus. It will be used to cool the diffusion pump trap. 60 refs.

  9. Total OH reactivity measurement in a BVOC dominated temperate forest during a summer campaign, 2014

    NASA Astrophysics Data System (ADS)

    Ramasamy, Sathiyamurthi; Ida, Akira; Jones, Charlotte; Kato, Shungo; Tsurumaru, Hiroshi; Kishimoto, Iori; Kawasaki, Shio; Sadanaga, Yasuhiro; Nakashima, Yoshihiro; Nakayama, Tomoki; Matsumi, Yutaka; Mochida, Michihiro; Kagami, Sara; Deng, Yange; Ogawa, Shuhei; Kawana, Kaori; Kajii, Yoshizumi

    2016-04-01

    A total OH reactivity measurement was conducted in coniferous forest located in Wakayama prefecture, Japan, during the summer of 2014. The average total OH reactivity, measured using a laser-induced pump and probe technique was 7.1 s-1. The measured OH reactivity was comparable with other coniferous and temperate forest measurements and much lower than that of tropical forests. OH reactivity varied diurnally and showed moderate linear correlation with temperature (r2 = 0.66) and light (r2 = 0.53). Monoterpene emitters, Cryptomeria japonica and Chamaecyparis obutsa, are the dominant tree species in this forest. Although clean air from the sea was predominant, the beginning of the campaign was influenced by transported anthropogenic pollutants and consequently a higher average OH reactivity of 9.8 s-1 with high missing sinks of 37.3% was determined. Cleaner conditions, along with cooler day-time temperatures during in the second half of the campaign resulted in a lower average OH reactivity of 6.0 s-1 with a lower missing OH reactivity of 21.5%. Monoterpenes, isoprene, acetaldehyde were the dominant contributors to the total OH reactivity, accounting for 23.7%, 17.0% and 14.5%, respectively.

  10. Rod-like particles matching algorithm based on SOM neural network in dispersed two-phase flow measurements

    NASA Astrophysics Data System (ADS)

    Abbasi Hoseini, Afshin; Zavareh, Zahra; Lundell, Fredrik; Anderson, Helge I.

    2014-04-01

    A matching algorithm based on self-organizing map (SOM) neural network is proposed for tracking rod-like particles in 2D optical measurements of dispersed two-phase flows. It is verified by both synthetic images of elongated particles mimicking 2D suspension flows and direct numerical simulations-based results of prolate particles dispersed in a turbulent channel flow. Furthermore, the potential benefit of this algorithm is evaluated by applying it to the experimental data of rod-like fibers tracking in wall turbulence. The study of the behavior of elongated particles suspended in turbulent flows has a practical importance and covers a wide range of applications in engineering and science. In experimental approach, particle tracking velocimetry of the dispersed phase has a key role together with particle image velocimetry of the carrier phase to obtain the velocities of both phases. The essential parts of particle tracking are to identify and match corresponding particles correctly in consecutive images. The present study is focused on the development of an algorithm for pairing non-spherical particles that have one major symmetry axis. The novel idea in the algorithm is to take the orientation of the particles into account for matching in addition to their positions. The method used is based on the SOM neural network that finds the most likely matching link in images on the basis of feature extraction and clustering. The fundamental concept is finding corresponding particles in the images with the nearest characteristics: position and orientation. The most effective aspect of this two-frame matching algorithm is that it does not require any preliminary knowledge of neither the flow field nor the particle behavior. Furthermore, using one additional characteristic of the non-spherical particles, namely their orientation, in addition to its coordinate vector, the pairing is improved both for more reliable matching at higher concentrations of dispersed particles and

  11. Dark adaptation of human rod bipolar cells measured from the b-wave of the scotopic electroretinogram

    PubMed Central

    Cameron, A M; Mahroo, O A R; Lamb, T D

    2006-01-01

    To examine the dark adaptation of human rod bipolar cells in vivo, we recorded ganzfeld ERGs to (a) a family of flashes of increasing intensity, (b) dim test flashes presented on a range of background intensities, and (c) dim test flashes presented before, and up to 40 min after, exposure to intense illumination eliciting bleaches from a few per cent to near total. The dim flash ERG was characterized by a prominent b-wave response generated principally by rod bipolar cells. In the presence of background illumination the response reached peak earlier and desensitized according to Weber's Law. Following bleaching exposures, the response was initially greatly desensitized, but thereafter recovered slowly with time. For small bleaches, the desensitization was accompanied by acceleration, in much the same way as for real light. Following a near-total bleach, the response was unrecordable for >10 min, but after ∼23 min half-maximal sensitivity was reached, and full sensitivity was restored between ∼35 and 40 min. With smaller bleaches, recovery commenced earlier. We converted the post-bleach measurements of desensitization into ‘equivalent background intensities’ using a Crawford transformation. Across the range of bleaching levels, the results were described by a prominent ‘S2’ component (0.24 decades min−1) together with a smaller and slower ‘S3’ component (0.06 decades min−1), as is found for dark adaptation of the scotopic visual system. We attribute the S2 component to the presence of unregenerated opsin, and we speculate that the S3 component results from ion channel closure by all-trans retinal. PMID:16777945

  12. Detailed characterization of a Comparative Reactivity Method (CRM) instrument for ambient OH reactivity measurements: experiments vs. modeling

    NASA Astrophysics Data System (ADS)

    Michoud, Vincent; Locoge, Nadine; Dusanter, Sébastien

    2015-04-01

    The Hydroxyl radical (OH) is the main daytime oxidant in the troposphere, leading to the oxidation of Volatile Organic Compounds (VOCs) and the formation of harmful pollutants such as ozone (O3) and Secondary Organic Aerosols (SOA). While OH plays a key role in tropospheric chemistry, recent studies have highlighted that there are still uncertainties associated with the OH budget, i.e the identification of sources and sinks and the quantification of production and loss rates of this radical. It has been demonstrated that ambient measurements of the total OH loss rate (also called total OH reactivity) can be used to identify and reduce these uncertainties. In this context, the Comparative Reactivity Method (CRM), developed by Sinha et al. (ACP, 2008), is a promising technique to measure total OH reactivity in ambient air and has already been used during several field campaigns. This technique relies on monitoring competitive reactions of OH with ambient trace gases and a reference compound (pyrrole) in a sampling reactor to derive ambient OH reactivity. However, this technique requires a complex data processing chain that has yet to be carefully investigated in the laboratory. In this study, we present a detailed characterization of a CRM instrument developed at Mines Douai, France. Experiments have been performed to investigate the dependence of the CRM response on humidity, ambient NOx levels, and the pyrrole-to-OH ratio inside the sampling reactor. Box modelling of the chemistry occurring in the reactor has also been performed to assess our theoretical understanding of the CRM measurement. This work shows that the CRM response is sensitive to both humidity and NOx, which can be accounted for during data processing using parameterizations depending on the pyrrole-to-OH ratio. The agreement observed between laboratory studies and model results suggests a good understanding of the chemistry occurring in the sampling reactor and gives confidence in the CRM

  13. An automated dynamic chamber system for surface exchange measurement of non-reactive and reactive trace gases of grassland ecosystems

    NASA Astrophysics Data System (ADS)

    Pape, L.; Ammann, C.; Nyfeler-Brunner, A.; Spirig, C.; Hens, K.; Meixner, F. X.

    2009-03-01

    We present an automated dynamic chamber system which is optimised for continuous unattended flux measurements of multiple non-reactive and reactive trace gases on grassland ecosystems. Main design features of our system are (a) highly transparent chamber walls consisting of chemically inert material, (b) individual purging flow units for each chamber, and (c) a movable lid for automated opening and closing of the chamber. The purging flow rate was chosen high enough to keep the mean residence time of the chamber air below one minute. This guarantees a proven efficient mixing of the chamber volume and a fast equilibration after lid closing. The dynamic chamber system is able to measure emission as well as deposition fluxes of trace gases. For the latter case, the modification of the turbulent transport by the chamber (compared to undisturbed ambient conditions) is quantitatively described by a bulk resistance concept. Beside a detailed description of the design and functioning of the system, results of field applications at two grassland sites are presented. In the first experiment, fluxes of five trace gases (CO2, H2O, NO, NO2, O3) were measured simultaneously on small grassland plots. It showed that the dynamic chamber system is able to detect the characteristic diurnal cycles with a sufficient temporal resolution. The results also demonstrated the importance of considering the chemical source/sink in the chamber due to gas phase reactions for the reactive compounds of the NO-NO2-O3 triad. In a second field experiment, chamber flux measurements of CO2 and methanol were compared to simultaneous independent eddy covariance flux measurements on the field scale. The fluxes obtained with the two methods showed a very good agreement indicating a minimal disturbance of the chambers on the physiological activity of the enclosed vegetation.

  14. An automated dynamic chamber system for surface exchange measurement of non-reactive and reactive trace gases of grassland ecosystems

    NASA Astrophysics Data System (ADS)

    Pape, L.; Ammann, C.; Nyfeler-Brunner, A.; Spirig, C.; Hens, K.; Meixner, F. X.

    2008-08-01

    We present an automated dynamic chamber system which is optimised for continuous unattended flux measurements of multiple non-reactive and reactive trace gases on grassland ecosystems. Main design features of our system are (a) highly transparent chamber walls consisting of chemically inert material, (b) individual purging flow units for each chamber, and (c) a movable lid for automated opening and closing of the chamber. The purging flow rate was chosen high enough to keep the mean residence time of the chamber air below one minute. This guarantees a proven efficient mixing of the chamber volume and a fast equilibration after lid closing. The dynamic chamber system is able to measure emission as well as deposition fluxes of trace gases. For the latter case, the modification of the turbulent transport by the chamber (compared to undisturbed ambient conditions) is quantitatively described by a bulk resistance concept. Beside a detailed description of the design and functioning of the system, results of field applications at two grassland sites are presented. In the first experiment, fluxes of five trace gases (CO2, H2O, NO, NO2, O3) were measured simultaneously on small grassland plots. It showed that the dynamic chamber system is able to detect the characteristic diurnal cycles with a sufficient temporal resolution. The results also demonstrated the importance of considering the chemical source/sink in the chamber due to gas phase reactions for the reactive compounds of the NO-NO2-O3 triad. In a second field experiment, chamber flux measurements of CO2 and methanol were compared to simultaneous independent eddy covariance flux measurements on the field scale. The fluxes obtained with the two methods showed a very good agreement indicating a minimal disturbance of the chambers on the physiological activity of the enclosed vegetation.

  15. Method of measuring reactive acoustic power density in a fluid

    DOEpatents

    Wheatley, John C.; Swift, Gregory W.; Migliori, Albert

    1985-01-01

    A method for determining reactive acoustic power density level and its direction in a fluid using a single sensor is disclosed. In the preferred embodiment, an apparatus for conducting the method, which is termed a thermoacoustic couple, consists of a stack of thin, spaced apart polymeric plates, selected ones of which include multiple bimetallic thermocouple junctions positioned along opposite end edges thereof. The thermocouple junctions are connected in series in the nature of a thermopile, and are arranged so as to be responsive to small temperature differences between the opposite edges of the plates. The magnitude of the temperature difference, as represented by the magnitude of the electrical potential difference generated by the thermopile, is found to be directly related to the level of acoustic power density in the gas.

  16. Method of measuring reactive acoustic power density in a fluid

    DOEpatents

    Wheatley, J.C.; Swift, G.W.; Migliori, A.

    1985-09-03

    A method for determining reactive acoustic power density level and its direction in a fluid using a single sensor is disclosed. In the preferred embodiment, an apparatus for conducting the method, which is termed a thermoacoustic couple, consists of a stack of thin, spaced apart polymeric plates, selected ones of which include multiple bimetallic thermocouple junctions positioned along opposite end edges thereof. The thermocouple junctions are connected in series in the nature of a thermopile, and are arranged so as to be responsive to small temperature differences between the opposite edges of the plates. The magnitude of the temperature difference, as represented by the magnitude of the electrical potential difference generated by the thermopile, is found to be directly related to the level of acoustic power density in the gas. 5 figs.

  17. Surface Strength of Silicon Nitride in Relation to Rolling Contact Performance Measured on Ball-on-Rod and Modified Four-Ball Tests

    SciTech Connect

    Wang, Wei; Hadfield, M.; Wereszczak, Andrew A

    2010-01-01

    Silicon nitride (Si{sub 3}N{sub 4}) has been used in various rolling contact applications in turbomachinery, automotive and power industry. It is favoured to replace conventional steel due to its low density, low friction, corrosion resistance and good performance under extreme condition. However, a major limitation of its wider application is its high material and machining cost, especially the cost associated with the finishing process. In the present study, a low cost sintered and reaction bonded silicon nitride (SRBSN) is used to study the surface machining effects on its rolling contact performance. Attempt has been made to link the surface strengths of Si{sub 3}N{sub 4} derived from half-rod and C-sphere flexure strength specimens to the rolling contact lifetimes of Si{sub 3}N{sub 4} rod and ball specimens. The rolling contact fatigue tests are carried out on ball-on-rod and modified four ball machines. Three types of surfaces with coarse, fine and conventional finishing conditions are examined. Flexure strength tests on half-rod and C-sphere show an increasing surface strength from specimens with coarse, fine to conventionally machined conditions. During rolling contact fatigue test of as-machined specimens, there are no failures observed on both ball-on-rod and four ball tests after 100 million stress cycles. However, there is a trend of decreasing wear volumes measured on the contact path of rods and balls with coarse, fine and conventional conditions. In four ball test, spall failures are observed on pre-crack specimens. There is a trend of increasing rolling contact fatigue lifetime from pre-cracked specimens with coarse, fine to conventional machining conditions.

  18. CONTROL ROD

    DOEpatents

    Zinn, W.H.; Ross, H.V.

    1958-11-18

    A control rod is described for a nuclear reactor. In certaln reactor designs it becomes desirable to use a control rod having great width but relatively llttle thickness. This patent is addressed to such a need. The neutron absorbing material is inserted in a triangular tube, leaving volds between the circular insert and the corners of the triangular tube. The material is positioned within the tube by the use of dummy spacers to achleve the desired absorption pattern, then the ends of the tubes are sealed with suitable plugs. The tubes may be welded or soldered together to form two flat surfaces of any desired width, and covered with sheetmetal to protect the tubes from damage. This design provides a control member that will not distort under the action of outside forces or be ruptured by gases generated within the jacketed control member.

  19. Control rods in LMFBRs: a physics assessment

    SciTech Connect

    McFarlane, H.F.; Collins, P.J.

    1982-08-01

    This physics assessment is based on roughly 300 control rod worth measurements in ZPPR from 1972 to 1981. All ZPPR assemblies simulated mixed-oxide LMFBRs, representing sizes of 350, 700, and 900 MWe. Control rod worth measurements included single rods, various combinations of rods, and Ta and Eu rods. Additional measurements studied variations in B/sub 4/C enrichment, rod interaction effects, variations in rod geometry, neutron streaming in sodium-filled channels, and axial worth profiles. Analyses were done with design-equivalent methods, using ENDF/B Version IV data. Some computations for the sensitivities to approximations in the methods have been included. Comparisons of these analyses with the experiments have allowed the status of control rod physics in the US to be clearly defined.

  20. Poly-Use Multi-Level Sampling Rod to Measure Soil-Gas Exchange in Glacier Forefield Soils

    NASA Astrophysics Data System (ADS)

    Nauer, P. A.; Schroth, M. H.; Zeyer, J. A.

    2012-12-01

    The forefields of receding glaciers provide unique opportunities to investigate initial microbial processes in the vadose zone and their role in soil formation. Various studies revealed a surprising diversity of microbes and of their strategies to cope with the extreme conditions in this C- and N-limited environment. In the forefield of receding glaciers as well as in developed soils microorganisms are the driving force for the exchange of greenhouse gases between soil and atmosphere. However, in young and developing soils, little is known about soil-gas exchange and the activities of the involved microorganisms. Knowledge of soil-gas composition and gas diffusion at various depths in a soil profile allows for the precise calculation of gas fluxes among different depths within the vadose zone and at the soil-atmosphere boundary. The acquisition of undisturbed soil-gas samples at a high depth-resolution is difficult, and the estimation of soil-gas diffusion coefficients requires knowledge of volumetric water content at the exact location of gas sampling. By using conventional techniques, e.g. the burial of permanent probes, these tasks are virtually impossible to accomplish in a remote glacier forefield dominated by rocks and boulders. We developed a novel poly-use multi-level sampling rod (PULSAR) primarily consisting of two devices: a newly-designed multi-level sampler (MLS) for soil-gas sampling, and a commercially available profile probe (PR2) for non-invasive multi-level water content measurements. These devices fit into the same access tubes (ATs) of 1.1m length, which need to be pre-installed into the soil with the help of a steel rod. We modified the ATs to feature eight 1mm diameter holes each at 20 sampling depths in intervals of 5cm. Our MLS can be inserted into the ATs and allows for the selective extraction of soil-gas from each sampling depth. The interspaces between the sampling depths are sealed by inflatable rubber membranes for the time of sampling

  1. Comparison of Total OH Reactivity Measurement Methods in Ambient Air between a Comparative Reactivity Method using PTR-MS and a LASER Technique

    NASA Astrophysics Data System (ADS)

    Okazaki, H.; Osada, T.; Nakashima, Y.; Kato, S.; Kajii, Y.

    2008-12-01

    OH radical plays an important role in atmospheric chemistry. OH reactivity measurement is essential to understand atmospheric chemical reaction processes. We have developed LASER technique to measure OH reactivity. This system requires both pump and probe lasers and high vacuum system. We have to pay a lot of efforts to bring the instrument in the field for ambient observation. Therefore we have developed a comparative reactivity method for measuring total OH reactivity recently. Since this method does not need a large space and complicated devices, it makes relatively easy to measure OH reactivity anywhere. The result of this non-laser OH reactivity measurement was compared with that of laser pump and probe technique as conducted an intensive field measurement of sub-urban air in Tokyo, July 2008. In comparative reactivity method, a regent species (X), which is ideally not present in ambient air, is introduced into the flow tube reactor and its concentration (C1) is monitored by a suitable detector under nitrogen atmospheric condition. A constant amount of OH radicals is then introduced into the flow tube to react with X under either nitrogen atmosphere (the concentration of X became C2) or ambient air (the concentration of X became C3). Total OH reactivity can be calculated by comparing C1, C2 and C3. OH radicals were produced in the photolysis of water vapor by a UV lamp. In our experiment, Pyrrole is selected as X and PTR-MS is used as a detector. The concentrations of NO, NO2, CO, SO2 were also measured. In some case, the two methods indicated some differences, for example, OH reactivity of 10 to 30 s-1 measured by LASER technique while the comparative reactivity method showed the value of only 5 to 12 s-1.This reason appears to be humidity dependence of PTR-MS sensitivity. Good agreements, for trends and absolute values, were found for comparison between the two methods during another day of experiment where both methods reveal OH reactivity ranging between

  2. OH reactivity measurements from Boreal tree species in a plant chamber

    NASA Astrophysics Data System (ADS)

    Nölscher, Anke; Custer, Thomas; Sinha, Vinayak; Kiendler-Scharr, Astrid; Kleist, Einhard; Tillmann, Ralf; Wildt, Jürgen; Williams, Jonathan

    2010-05-01

    Boreal forest covers a large area (ca. 15 million km2) comparable in size to the Tropical rain forest (ca. 17 million km2). The vegetation in Boreal regions is typically conifer forest which is known to emit significant amounts of biogenic volatile organic compounds (BVOCS), such as monoterpenes, sesquiterpenes, methanol and acetone. Many of these organic chemicals react rapidly with hydroxyl (OH) radicals to produce aerosols or secondary pollutants such as ozone. The total effect of the emitted species on the OH radical can be determined by measuring the total OH reactivity directly. Therefore a new measurement method was recently devised (Sinha et al., 2008). The Jülich plant atmosphere chamber (JPAC) at the Forschungszentrum-Jülich was used to investigate the overall reactivity of emissions from several Boreal tree species under controlled conditions in October 2009. Vegetation, temperature and light intensities typical of the Hyytiälä measurement station in Finland were used in these experiments and the levels of CO2, humidity and NOx were controlled. In addition to the reactivity measurement, a gas chromatograph (GC), a proton transfer reaction mass spectrometer (PTRMS) and a time-of-flight PTRMS (TOF-PTRMS) were used to quantify individual organic chemicals emitted by the plants for comparison with the overall reactivity. Experiments were performed under three different conditions. 1) Lower temperatures (T=20° C) resulted in low plant emissions with no diurnal variation. The total measured OH reactivity ranged from below detection limit (3 sec-1) to 7 sec-1 during the day and overnight rose to 8-13 sec-1. 2) Higher temperatures (T=35° C) produced higher emissions of volatile organic compounds and a clear diurnal trend. Reactivity data matched well with these results rising to 30-50 sec-1 by day and during the night sinking again to 8-13 sec-1. 3) Finally a control experiment was performed without trees in the plant chamber. In this experiment

  3. Measurements of reactive gaseous rocket injector response factors

    NASA Technical Reports Server (NTRS)

    Janardan, B. A.; Daniel, B. R.; Bell, W. A.; Zinn, B. T.

    1977-01-01

    The results presented represent the first successful attempt at the measurement of the driving capabilities of coaxial gaseous propellant rocket injectors. The required data have been obtained by employing the modified impedance tube technique with compressed air as the oxidizer and acetylene gas as the fuel. The data describe the frequency dependence of the injector admittances, from which the frequency dependence of the injection response factors can be calculated. The measured injector admittances have been compared with the predictions of the Feiler and Heidmann (1967) analytical model assuming different values for the characteristic combustion time. The values of combustion time which result in a best fit between the measured and predicted data are indicated for different equivalence ratios. It is shown that for the coaxial injector system investigated in this study the characteristic combustion times vary between .7 and 1.2 msec for equivalence ratios in the range of .57 to 1.31. The experimental data clearly show that the tested injector system could indeed drive combustion instabilities over a frequency range that is in qualitative agreement with the predictions of the Feiler and Heidmann model.

  4. Measuring physical activity with pedometers in older adults with intellectual disability: reactivity and number of days.

    PubMed

    Hilgenkamp, Thessa; Van Wijck, Ruud; Evenhuis, Heleen

    2012-08-01

    The minimum number of days of pedometer monitoring needed to estimate valid average weekly step counts and reactivity was investigated for older adults with intellectual disability. Participants (N  =  268) with borderline to severe intellectual disability ages 50 years and older were instructed to wear a pedometer for 14 days. The outcome measure was steps per day. Reactivity was investigated with repeated measures analysis of variance, and monitoring frame was assessed by comparing combinations of days with average weekly step counts (with intraclass correlation coefficients [ICCs] and regression analyses). No reactivity was present. Any combination of 4 days resulted in ICCs of 0.96 or higher and 90% of explained variance. The study concludes that any 4 days of wearing a pedometer is sufficient to validly measure physical activity in older adults with intellectual disability. PMID:22861135

  5. Layered reactive particles with controlled geometries, energies, and reactivities, and methods for making the same

    DOEpatents

    Fritz, Gregory M; Knepper, Robert Allen; Weihs, Timothy P; Gash, Alexander E; Sze, John S

    2013-04-30

    An energetic composite having a plurality of reactive particles each having a reactive multilayer construction formed by successively depositing reactive layers on a rod-shaped substrate having a longitudinal axis, dividing the reactive-layer-deposited rod-shaped substrate into a plurality of substantially uniform longitudinal segments, and removing the rod-shaped substrate from the longitudinal segments, so that the reactive particles have a controlled, substantially uniform, cylindrically curved or otherwise rod-contoured geometry which facilitates handling and improves its packing fraction, while the reactant multilayer construction controls the stability, reactivity and energy density of the energetic composite.

  6. Layered reactive particles with controlled geometries, energies, and reactivities, and methods for making the same

    DOEpatents

    Fritz, Gregory M.; Weihs, Timothy P.; Grzyb, Justin A.

    2016-07-05

    An energetic composite having a plurality of reactive particles each having a reactive multilayer construction formed by successively depositing reactive layers on a rod-shaped substrate having a longitudinal axis, dividing the reactive-layer-deposited rod-shaped substrate into a plurality of substantially uniform longitudinal segments, and removing the rod-shaped substrate from the longitudinal segments, so that the reactive particles have a controlled, substantially uniform, cylindrically curved or otherwise rod-contoured geometry which facilitates handling and improves its packing fraction, while the reactant multilayer construction controls the stability, reactivity and energy density of the energetic composite.

  7. Advanced gray rod control assembly

    DOEpatents

    Drudy, Keith J; Carlson, William R; Conner, Michael E; Goldenfield, Mark; Hone, Michael J; Long, Jr., Carroll J; Parkinson, Jerod; Pomirleanu, Radu O

    2013-09-17

    An advanced gray rod control assembly (GRCA) for a nuclear reactor. The GRCA provides controlled insertion of gray rod assemblies into the reactor, thereby controlling the rate of power produced by the reactor and providing reactivity control at full power. Each gray rod assembly includes an elongated tubular member, a primary neutron-absorber disposed within the tubular member said neutron-absorber comprising an absorber material, preferably tungsten, having a 2200 m/s neutron absorption microscopic capture cross-section of from 10 to 30 barns. An internal support tube can be positioned between the primary absorber and the tubular member as a secondary absorber to enhance neutron absorption, absorber depletion, assembly weight, and assembly heat transfer characteristics.

  8. Intercomparison of the comparative reactivity method (CRM) and pump-probe technique for measuring total OH reactivity in an urban environment

    NASA Astrophysics Data System (ADS)

    Hansen, R. F.; Blocquet, M.; Schoemaecker, C.; Léonardis, T.; Locoge, N.; Fittschen, C.; Hanoune, B.; Stevens, P. S.; Sinha, V.; Dusanter, S.

    2015-10-01

    The investigation of hydroxyl radical (OH) chemistry during intensive field campaigns has led to the development of several techniques dedicated to ambient measurements of total OH reactivity, which is the inverse of the OH lifetime. Three techniques are currently used during field campaigns, including the total OH loss rate method, the pump-probe method, and the comparative reactivity method. However, no formal intercomparison of these techniques has been published so far, and there is a need to ensure that measurements of total OH reactivity are consistent among the different techniques. An intercomparison of two OH reactivity instruments, one based on the comparative reactivity method (CRM) and the other based on the pump-probe method, was performed in October 2012 in a NOx-rich environment, which is known to be challenging for the CRM technique. This study presents an extensive description of the two instruments, the CRM instrument from Mines Douai (MD-CRM) and the pump-probe instrument from the University of Lille (UL-FAGE), and highlights instrumental issues associated with the two techniques. It was found that the CRM instrument used in this study underestimates ambient OH reactivity by approximately 20 % due to the photolysis of volatile organic compounds (VOCs) inside the sampling reactor; this value is dependent on the position of the lamp within the reactor. However, this issue can easily be fixed, and the photolysis of VOCs was successfully reduced to a negligible level after this intercomparison campaign. The UL-FAGE instrument may also underestimate ambient OH reactivity due to the difficulty to accurately measure the instrumental zero. It was found that the measurements are likely biased by approximately 2 s-1, due to impurities in humid zero air. Two weeks of ambient sampling indicate that the measurements performed by the two OH reactivity instruments are in agreement, within the measurement uncertainties for each instrument, for NOx mixing ratios

  9. Intercomparison of the comparative reactivity method (CRM) and pump-probe technique for measuring total OH reactivity in an urban environment

    NASA Astrophysics Data System (ADS)

    Hansen, R. F.; Blocquet, M.; Schoemaecker, C.; Léonardis, T.; Locoge, N.; Fittschen, C.; Hanoune, B.; Stevens, P. S.; Sinha, V.; Dusanter, S.

    2015-06-01

    The investigation of hydroxyl radical (OH) chemistry during intensive field campaigns has led to the development of several techniques dedicated to ambient measurements of total OH reactivity, which is the inverse of the OH lifetime. Three techniques are currently used during field campaigns, including the total OH loss rate method, the pump-probe method, and the comparative reactivity method. However, no formal intercomparison of these techniques has been published so far, and there is a need to ensure that measurements of total OH reactivity are consistent among the different techniques. An intercomparison of two OH reactivity instruments, one based on the Comparative Reactivity Method (CRM) and the other based on the pump-probe method, was performed in October 2012 in a NOx-rich environment, which is known to be challenging for the CRM technique. This study presents an extensive description of the two instruments, the CRM instrument from Mines Douai (MD-CRM) and the pump-probe instrument from the University of Lille (UL-FAGE), and highlights instrumental issues associated with the two techniques. It was found that the CRM instrument used in this study underestimates ambient OH reactivity by approximately 20 % due to the photolysis of Volatile Organic Compounds (VOCs) inside the sampling reactor; this value is dependent on the position of the lamp within the reactor. However, this issue can easily be fixed, and the photolysis of VOCs was successfully reduced to a negligible level after this intercomparison campaign. The UL-FAGE instrument may also underestimate ambient OH reactivity due to the difficulty to accurately measure the instrumental zero. It was found that the measurements are likely biased by approximately 2 s-1, due to impurities in humid zero air. Two weeks of ambient sampling indicate that the measurements performed by the two OH reactivity instruments are in agreement, within the measurement uncertainties for each instrument, for NOx mixing ratios

  10. Reactivity worth measurements at the IPEN/MB-01 nuclear reactor

    SciTech Connect

    Pinto, Leticia Negrao; Santos, Adimir dos

    2013-05-06

    Researches that aim to improve the performance of neutron transport codes and quality of nuclear cross section databases are very important to increase the accuracy of simulations and the quality of the analysis and prediction of phenomena in the nuclear field. In this context, relevant experimental data such as reactivity worth measurements are needed. The objective of this work was to perform a series of experiments of reactivity worth measurements, using a digital reactivity meter developed at IPEN. The experiments employed small metallic and ceramic samples inserted in the central region of the core of the experimental IPEN/MB-01 reactor. The theoretical analysis was performed by the MCNP-5 reactor physics code, developed and maintained by Los Alamos National Laboratory, and the ENDF/B-VII.0 nuclear data library.

  11. Specimen size and geometry effects on fracture toughness of Al2O3 measured with short rod and short bar chevron-notch specimens

    NASA Technical Reports Server (NTRS)

    Shannon, J. L., Jr.; Munz, D. G.

    1983-01-01

    Plane strain fracture toughness measurements were made on Al2O3 using short rod and short bar chevron notch specimens previously calibrated by the authors for their dimensionless stress intensity factor coefficients. The measured toughness varied systematically with variations in specimen size, proportions, and chevron notch angle apparently due to their influence on the amount of crack extension to maximum load (the measurement point). The toughness variations are explained in terms of a suspected rising R curve for the material tested, along with a discussion of an unavoidable imprecision in the calculation of K sub Ic for materials with rising R curves when tested with chevron notch specimens.

  12. ADVANCED REACTIVITY MEASUREMENT FACILITY, TRA660, INTERIOR. REACTOR INSIDE TANK. METAL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    ADVANCED REACTIVITY MEASUREMENT FACILITY, TRA-660, INTERIOR. REACTOR INSIDE TANK. METAL WORK PLATFORM ABOVE. THE REACTOR WAS IN A SMALL WATER-FILLED POOL. INL NEGATIVE NO. 66-6373. Unknown Photographer, ca. 1966 - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID

  13. Summer 2015 measurements of total OH reactivity at a UK coastal site

    NASA Astrophysics Data System (ADS)

    Woodward-Massey, R.; Cryer, D. R.; Whalley, L. K.; Ingham, T.; Crilley, L.; Kramer, L. J.; Reeves, C.; Forster, G.; Oram, D.; Bandy, B.; Reed, C.; Lee, J. D.; Bloss, W.; Heard, D. E.

    2015-12-01

    The hydroxyl radical (OH) plays a central role in the day time oxidative removal of pollutants and greenhouse gases in the atmosphere. It is essential that all production and loss pathways of OH are understood and included in computer models in order to accurately predict OH concentrations for a range of environments, and in turn the rate of production of secondary products, for example ozone and organic aerosol. Direct measurement of total OH reactivity, the pseudo first order rate coefficient for OH loss by reaction with its sinks, is a very useful tool to test how complete our knowledge is of OH loss pathways. Comparison with values of total OH reactivity calculated by computer models using concentrations of simultaneously measured OH 'sinks' and unmeasured intermediates enables environments to be identified where there are unidentified 'missing' OH sinks. Total OH reactivity was measured using the laser flash photolysis combined with time-resolved laser-induced fluorescence technique during the ICOZA (Integrated Chemistry of OZone in the Atmosphere) campaign in July 2015 at the Weybourne Atmospheric Observatory (WAO), Norfolk, UK. Air masses sampled ranged from polluted air from the UK or Europe containing processed urban emissions to very clean air of marine origin. Data for measured and calculated OH reactivity will be presented in addition to a discussion of the magnitude of the 'missing' OH sink determined for each type of air mass.

  14. Measurement Reactivity and Fatigue Effects in Daily Diary Research with Families

    ERIC Educational Resources Information Center

    Reynolds, Bridget M.; Robles, Theodore F.; Repetti, Rena L.

    2016-01-01

    Methodological challenges associated with measurement reactivity and fatigue were addressed using diary data collected from mothers (n = 47), fathers (n = 39), and children (n = 47; 8-13 years) across 56 consecutive days. Demonstrating the feasibility of extended diary studies with families, on-time compliance rates were upward of 90% for all…

  15. Measurements of Reactive Iodine Species on the Isles of Shoals, Gulf of Maine

    NASA Astrophysics Data System (ADS)

    Pikelnaya, O.; Hurlock, S. C.; Trick, S.; Stutz, J.

    2005-12-01

    The chemistry of reactive iodine species has received considerable attention in the past five years. The presence of iodine oxides in the marine boundary layer (MBL) can influence ozone levels, either through well-known catalytic destruction cycles, or through its influence on NO/NO2 and OH/HO2 ratios. In addition, iodine oxides have been linked to aerosol nucleation events in the MBL. Currently, the observational database on reactive iodine species is limited to a very few geographical locations, and the levels of reactive iodine compounds along the North American coast are currently unknown. This lack of information severely restricts our ability to assess the significance of iodine chemistry on a global scale. Here we present the first observations of IO, OIO, and I2 on the Isles of Shoals, Gulf of Maine, during ICARTT 2004, using simultaneous measurements by long-path (LP) and a multi-axis (MAX) differential optical absorption spectroscopy (DOAS) systems.. Both instruments clearly identified reactive iodine species. IO mixing ratios reached 7ppt on several days. OIO was observed during the day, while I2 was elevated at night. Our observations will be discussed with respect to the current knowledge of iodine chemistry, possible iodine sources, and the influence of iodine chemistry on ozone concentrations and aerosol nucleation. Prospects for deriving spatial distributions of reactive iodine species will also be discussed.

  16. An overview of reactive chlorine measurements during the WINTER C-130 aircraft campaign

    NASA Astrophysics Data System (ADS)

    Thornton, J. A.; Lopez-Hilfiker, F.; Lee, B. H.; Jaegle, L.; Haskins, J.; Shah, V.; Brown, S. S.; Fibiger, D. L.; McDuffie, E. E.; Veres, P. R.; Dibb, J. E.; Sparks, T.; Ebben, C. J.; Cohen, R. C.; Sullivan, A.; Guo, H.; Weber, R. J.; Schroder, J. C.; Campuzano-Jost, P.; Day, D. A.; Jimenez, J. L.; Campos, T. L.; Weinheimer, A. J.; Apel, E. C.; Blake, N. J.

    2015-12-01

    As part of the Wintertime Investigation of Transport, Emissions, and Reactivity (WINTER) campaign, the University of Washington Iodide-adduct high resolution time of flight chemical ionization mass spectrometer (HRToF-CIMS) was deployed aboard the NSF/NCAR C-130 aircraft. Calibrated measurements of ClNO2, Cl2, HCl, N2O5, HNO3, HONO, among several other compounds, were made at 2Hz on all 13 research flights. ClNO2 and HCl were often the dominant forms of reactive gas-phase chlorine compounds, with ClNO2 routinely reaching >1.5 ppb in the polluted outflow of the eastern U.S. urban corridor. ClNO2 often becomes a substantial fraction (~30%) of NOz (NOz = NOy - NOx) in these plumes at night. Preliminary analyses suggests that ClNO2 production is most efficient in the polluted marine boundary layer, with yields approaching unity and the evolution of nighttime ClNO2 highly correlated with that of HNO3 and particulate nitrate. However, ClNO2 production was observed throughout the region and a significant source of reactive chlorine from coal-fired power plants was directly confirmed with measurements of HCl strongly correlated with SO2. In addition, there is some evidence that biomass or biofuel combustion is a source of reactive chlorine that can lead to ClNO2 production. Examples of the nocturnal and diel evolution of reactive chlorine species are given, and we show to our knowledge the first measurements of chlorine nitrate (ClONO2) in the polluted mid-latitude marine boundary layer.

  17. FUEL ROD ASSEMBLY

    DOEpatents

    Hutter, E.

    1959-09-01

    A cluster of nuclear fuel rods aod a tubular casing through which a coolant flows in heat-change contact with the ruel rods are described. The casting is of trefoil section and carries the fuel rods, each of which has two fin engaging the serrated fins of the other two fuel rods, whereby the fuel rods are held in the casing and are interlocked against relative longitudinal movement.

  18. Differentiating Challenge Reactivity from Psychomotor Activity in Studies of Children’s Psychophysiology: Considerations for Theory and Measurement

    PubMed Central

    Bush, Nicole R.; Alkon, Abbey; Obradović, Jelena; Stamperdahl, Juliet; Boyce, W. Thomas

    2014-01-01

    Current methods of assessing children’s physiologic “stress reactivity” may be confounded by psychomotor activity, biasing estimates of the relation between reactivity and health. We examine the joint and independent contributions of psychomotor activity and challenge reactivity during a protocol for children ages 5–6 (N=338). Measures of parasympathetic (RSA) and sympathetic (PEP) reactivity were calculated for social, cognitive, sensory, and emotional challenge tasks. Reactivity was calculated relative to both resting and a paired comparison task that accounted for psychomotor activity effects during each challenge. Results indicated that comparison tasks themselves elicited RSA and PEP responses, and reactivity adjusted for psychomotor activity was incongruent with reactivity calculated using rest. Findings demonstrate the importance of accounting for confounding psychomotor activity effects on physiologic reactivity. PMID:21524757

  19. Variable flow control for a nuclear reactor control rod

    DOEpatents

    Carleton, Richard D.; Bhattacharyya, Ajay

    1978-01-01

    A variable flow control for a control rod assembly of a nuclear reactor that depends on turbulent friction though an annulus. The annulus is formed by a piston attached to the control rod drive shaft and a housing or sleeve fitted to the enclosure housing the control rod. As the nuclear fuel is burned up and the need exists for increased reactivity, the control rods are withdrawn, which increases the length of the annulus and decreases the rate of coolant flow through the control rod assembly.

  20. A new method for total OH reactivity measurements using a fast Gas Chromatographic Photo-Ionization Detector (GC-PID)

    NASA Astrophysics Data System (ADS)

    Nölscher, A. C.; Sinha, V.; Bockisch, S.; Klüpfel, T.; Williams, J.

    2012-05-01

    The primary and most important oxidant in the atmosphere is the hydroxyl radical (OH). Currently OH sinks, particularly gas phase reactions, are poorly constrained. One way to characterize the overall sink of OH is to measure directly the ambient loss rate of OH, the total OH reactivity. To date direct measurements of total OH reactivity have been either performed using a Laser Induced Fluorescence (LIF) system ("pump-and-probe" or "flow reactor") or the Comparative Reactivity Method (CRM) with a Proton Transfer Reaction Mass Spectrometer (PTR-MS). Both techniques require large, complex and expensive detection systems. This study presents a feasibility assessment for CRM total OH reactivity measurements using a new detector, a Gas Chromatographic Photo-Ionization Detector (GC-PID). Such a system is smaller, more portable, less power consuming and less expensive than other total OH reactivity measurement techniques. Total OH reactivity is measured by the CRM using a competitive reaction between a reagent (here pyrrole) with OH alone and in the presence of atmospheric reactive molecules. The new CRM method for total OH reactivity has been tested with parallel measurements of the GC-PID and the previously validated PTR-MS as detector for the reagent pyrrole during laboratory experiments, plant chamber and boreal field studies. Excellent agreement of both detectors was found when the GC-PID was operated under optimum conditions. Time resolution (60-70 s), sensitivity (LOD 3-6 s-1) and overall uncertainty (25% in optimum conditions) for total OH reactivity were equivalent to PTR-MS based total OH reactivity measurements. One drawback of the GC-PID system was the steady loss of sensitivity and accuracy during intensive measurements lasting several weeks, and a possible toluene interference. Generally, the GC-PID system has been shown to produce closely comparable results to the PTR-MS and thus in suitable environments (e.g. forests) it presents a viably economical

  1. Total OH reactivity measurements using a new fast Gas Chromatographic Photo-Ionization Detector (GC-PID)

    NASA Astrophysics Data System (ADS)

    Nölscher, A. C.; Sinha, V.; Bockisch, S.; Klüpfel, T.; Williams, J.

    2012-12-01

    The primary and most important oxidant in the atmosphere is the hydroxyl radical (OH). Currently OH sinks, particularly gas phase reactions, are poorly constrained. One way to characterize the overall sink of OH is to measure directly the ambient loss rate of OH, the total OH reactivity. To date, direct measurements of total OH reactivity have been either performed using a Laser-Induced Fluorescence (LIF) system ("pump-and-probe" or "flow reactor") or the Comparative Reactivity Method (CRM) with a Proton-Transfer-Reaction Mass Spectrometer (PTR-MS). Both techniques require large, complex and expensive detection systems. This study presents a feasibility assessment for CRM total OH reactivity measurements using a new detector, a Gas Chromatographic Photoionization Detector (GC-PID). Such a system is smaller, more portable, less power consuming and less expensive than other total OH reactivity measurement techniques. Total OH reactivity is measured by the CRM using a competitive reaction between a reagent (here pyrrole) with OH alone and in the presence of atmospheric reactive molecules. The new CRM method for total OH reactivity has been tested with parallel measurements of the GC-PID and the previously validated PTR-MS as detector for the reagent pyrrole during laboratory experiments, plant chamber and boreal field studies. Excellent agreement of both detectors was found when the GC-PID was operated under optimum conditions. Time resolution (60-70 s), sensitivity (LOD 3-6 s-1) and overall uncertainty (25% in optimum conditions) for total OH reactivity were similar to PTR-MS based total OH reactivity measurements. One drawback of the GC-PID system was the steady loss of sensitivity and accuracy during intensive measurements lasting several weeks, and a possible toluene interference. Generally, the GC-PID system has been shown to produce closely comparable results to the PTR-MS and thus in suitable environments (e.g. forests) it presents a viably economical

  2. Reactivity in Rapidly Collected Hygiene and Toilet Spot Check Measurements: A Cautionary Note for Longitudinal Studies

    PubMed Central

    Arnold, Benjamin F.; Khush, Ranjiv S.; Ramaswamy, Padmavathi; Rajkumar, Paramasivan; Durairaj, Natesan; Ramaprabha, Prabhakar; Balakrishnan, Kalpana; Colford Jr., John M.

    2015-01-01

    Discreet collection of spot check observations to measure household hygiene conditions is a common measurement technique in epidemiologic studies of hygiene in low-income countries. The objective of this study was to determine whether the collection of spot check observations in longitudinal studies could itself induce reactivity (i.e., change participant behavior). We analyzed data from a 12-month prospective cohort study in rural Tamil Nadu, India that was conducted in the absence of any hygiene or toilet promotion activities. Our data included hygiene and toilet spot checks from 10,427 household visits. We found substantial evidence of participant reactivity to spot check observations of hygiene practices that were easy to modify on short notice. For example, soap observed at the household's primary handwashing location increased from 49% at enrollment to 81% by the fourth visit and remained at or above 77% for the remainder of the study. PMID:25385856

  3. Measurements of NO and total reactive odd-nitrogen, NOy, in the Antarctic stratosphere

    NASA Technical Reports Server (NTRS)

    Fahey, D. W.; Murphy, D. M.; Eubank, C. S.; Ferry, G. V.; Chan, K. Roland; Ko, Malcolm K. W.

    1988-01-01

    Measurements of NO and total reactive N, NOy, were made as part of the Airborne Antarctic Ozone Experiment conducted in Punta Arenas, Chile during Aug. and Sept. 1987. The total reactive N reservoir includes the species NO, NO2, NO3, N2 O5, HNO3, and ClONO2. The instrument was located on board the NASA ER2 aircraft which conducted 12 flights over the Antarctic continent reaching altitudes of 18 km at 72 deg S latitude. The NOy technique utilized the conversion of component NOy species to NO on a gold catalyst and the subsequent detection of NO by the chemiluminescence reaction of NO with ozone. Since the inlet sample line is heated and the catalyst operates at 300 C, NOy incorporated in aerosols evaporates and is converted to NO. NO was measured on two separate flights by removing the catalyst from the sample inlet line.

  4. Baseline and reactivity measures of blood pressure and negative affect in borderline hypertension.

    PubMed

    Waked, E G; Jutai, J W

    1990-02-01

    Measures of blood pressure (BP) and negative affect were taken prior to, immediately following, and ten minutes after a cognitive stressor in groups of normotensive (group N; n = 15) and borderline hypertensive (group B; n = 15) young adults. Two testing sessions, one week apart, involved performance of a simple, congruent color-word ("easy") and a cognitive stress-inducing, incongruent color-word ("difficult") version of the Stroop test. In both sessions, group B showed significantly higher baseline systolic and diastolic BP, higher systolic responses to the difficult Stroop task, and higher recovery measures of systolic and diastolic BP than group N. In general, group B had significantly elevated baseline and reactivity scores on state measures of negative affect in both sessions. Correlations revealed strong positive associations between blood pressure and mood reactivity only for borderline subjects. Depressed mood was more strongly and consistently related to blood pressure reactivity than was hostility. Borderline hypertension appears to be associated with stable, perhaps clinically significant elevations in negative affect, and with dysphoric response to mild cognitive stress. PMID:2333341

  5. Reactivity initiated accident test series Test RIA 1-4

    SciTech Connect

    Martinson, Z.R.; El-Genk, M.S.; Fukuda, S.K.; LaPointe, R.E.; Osetek, D.J.

    1980-05-01

    The Reactivity Initiated Accident (RIA) Test RIA 1-4, the first 9-rod fuel rod bundle RIA Test to be performed at BWR hot startup conditions, was completed on April 16, 1980. The test was performed in the Power Burst Facility (PBF). Objective for Test RIA 1-4 was to provide information regarding loss-of-coolable fuel rod geometry following a RIA event for a peak fuel enthalpy equivalent to the present licensing criteria of 280 cal/g. The most severe RIA is the postulated Boiling Water Reactor (BWR) control rod drop during reactor startup. Therefore the test was conducted at BWR hot startup coolant conditions (538 K, 6.45 MPa, 0.8 1/sec). The test sequence began with steady power operation to condition the fuel, establish a short-lived fission product inventory, and calibrate the calorimetric measurements and core power chambers, neutron flux and gamma flux detectors. The test train was removed from the in-pile tube (IPT) to replace one of the fuel rods with a nominally identical irradiated rod and twelve flux wire monitors. A 2.8 ms period power burst was then performed. Coolant flow measurements were made before and after the power burst to characterize the flow blockage that occurred as a result of fuel rod failure.

  6. Development of airborne eddy-correlation flux measurement capabilities for reactive oxides of nitrogen

    NASA Technical Reports Server (NTRS)

    Bradshaw, John (Principal Investigator); Zheng, Xiaonan; Sandholm, Scott T.

    1996-01-01

    This research is aimed at producing a fundamental new research tool for characterizing the source strength of the most important compound controlling the hemispheric and global scale distribution of tropospheric ozone. Specifically, this effort seeks to demonstrate the proof-of-concept of a new general purpose laser-induced fluorescence based spectrometer for making airborne eddy-correlation flux measurements of nitric oxide (NO) and other reactive nitrogen compounds. The new all solid-state laser technology being used in this advanced sensor will produce a forerunner of the type of sensor technology that should eventually result in highly compact operational systems. The proof-of-concept sensor being developed will have over two orders-of-magnitude greater sensitivity than present-day instruments. In addition, this sensor will offer the possibility of eventual extension to airborne eddy-correlation flux measurements of nitrogen dioxide (NO2) and possibly other compounds, such as ammonia (NH3), peroxyradicals (HO2), nitrateradicals (NO3) and several iodine compounds (e.g., I and IO). Demonstration of the new sensor's ability to measure NO fluxes will occur through a series of laboratory and field tests. This proof-of-concept demonstration will show that not only can airborne fluxes of important ultra-trace compounds be made at the few parts-per-trillion level, but that the high accuracy/precision measurements currently needed for predictive models can also. These measurement capabilities will greatly enhance our current ability to quantify the fluxes of reactive nitrogen into the troposphere and significantly impact upon the accuracy of predictive capabilities to model O3's distribution within the remote troposphere. This development effort also offers a timely approach for producing the reactive nitrogen flux measurement capabilities that will be needed by future research programs such as NASA's planned 1999 Amazon Biogeochemistry and Atmospheric Chemistry

  7. Reactivation of slow-moving landslides by earthquakes, kinematics measurements and mechanical implications

    NASA Astrophysics Data System (ADS)

    Lacroix, Pascal; Perfettini, Hugo; Berthier, Etienne; Taipe, Edu; Guillier, Bertrand

    2015-04-01

    Major earthquakes in mountainous areas often trigger landslides. The impact of earthquakes on slow-moving landslides is however not well constrained due to few co-seismic measurements of landslide motion. We document the first time-series of a landslide reactivation by an earthquake (Mw6.0, distance 20 km), using continuous GPS measurements over the Maca landslide (Peru). Our survey shows a coseismic response of the landslide of about 2 cm, followed by a relaxation period of 5 weeks during which postseismic slip is three times greater than the coseismic displacement itself. Our results confirm the coseismic activation of landslides and provide the first observation of a post seismic displacement. Finally, a multi-temporal survey using images from the very high resolution Pléiades optical satellite, allowed us to detect 9 active slow-moving landslides over the whole valley. Their pattern of motion show they have been reactivated by the same earthquake. We analyze this small but comprehensive database of landslides reactivated by the earthquake. We find that the landslide motion due to the earthquake is function of the shaking intensity, suggesting a friction at the basal interface dependent on the earthquake solicitation. These various observations are consistent with a mechanical model where slip on the landslide basal interface is governed by rate and state friction, analogous to the mechanics of creeping tectonic faults.

  8. Reactive Strength Index Modified Is a Valid Measure of Explosiveness in Collegiate Female Volleyball Players.

    PubMed

    Kipp, Kristof; Kiely, Michael T; Geiser, Christopher F

    2016-05-01

    The purpose of this study was to investigate the validity of the reactive strength index modified (RSImod) as a measure of lower body explosiveness. Fifteen female, National Collegiate Athletic Association Division I volleyball players performed vertical countermovement jumps (CMJs) while standing on a force plate. Each player performed 3 CMJs. The vertical ground reaction forces collected during each jump were used to calculate jump height, time to take-off, time to peak force, peak force, peak rate of force development, and peak power; the latter 3 variables were all normalized to body mass. Reactive strength index modified was calculated as the ratio between jump height and time to take-off. All variables, except for jump height, were then entered a factor analysis, which reduced the input data into 2 factors: a force factor and a speed factor. Although RSImod loaded more strongly onto the force factor, further analysis showed that RSImod loaded positively onto both force and speed factors. Visual analysis of the Cartesian coordinates also showed that RSImod loaded into the quadrant of greater force and speed abilities. These results indicate that the construct of RSImod, as derived from CMJ force-time data, captures a combination of speed-force factors that can be interpreted as lower body explosiveness during the CMJ. Reactive strength index modified therefore seems to be a valid measure to study lower body explosiveness. PMID:26439787

  9. GUINEVERE experiment: Kinetic analysis of some reactivity measurement methods by deterministic and Monte Carlo codes

    SciTech Connect

    Bianchini, G.; Burgio, N.; Carta, M.; Peluso, V.; Fabrizio, V.; Ricci, L.

    2012-07-01

    The GUINEVERE experiment (Generation of Uninterrupted Intense Neutrons at the lead Venus Reactor) is an experimental program in support of the ADS technology presently carried out at SCK-CEN in Mol (Belgium). In the experiment a modified lay-out of the original thermal VENUS critical facility is coupled to an accelerator, built by the French body CNRS in Grenoble, working in both continuous and pulsed mode and delivering 14 MeV neutrons by bombardment of deuterons on a tritium-target. The modified lay-out of the facility consists of a fast subcritical core made of 30% U-235 enriched metallic Uranium in a lead matrix. Several off-line and on-line reactivity measurement techniques will be investigated during the experimental campaign. This report is focused on the simulation by deterministic (ERANOS French code) and Monte Carlo (MCNPX US code) calculations of three reactivity measurement techniques, Slope ({alpha}-fitting), Area-ratio and Source-jerk, applied to a GUINEVERE subcritical configuration (namely SC1). The inferred reactivity, in dollar units, by the Area-ratio method shows an overall agreement between the two deterministic and Monte Carlo computational approaches, whereas the MCNPX Source-jerk results are affected by large uncertainties and allow only partial conclusions about the comparison. Finally, no particular spatial dependence of the results is observed in the case of the GUINEVERE SC1 subcritical configuration. (authors)

  10. Connexin 36 and rod bipolar cell independent rod pathways drive retinal ganglion cells and optokinetic reflexes.

    PubMed

    Cowan, Cameron S; Abd-El-Barr, Muhammad; van der Heijden, Meike; Lo, Eric M; Paul, David; Bramblett, Debra E; Lem, Janis; Simons, David L; Wu, Samuel M

    2016-02-01

    Rod pathways are a parallel set of synaptic connections which enable night vision by relaying and processing rod photoreceptor light responses. We use dim light stimuli to isolate rod pathway contributions to downstream light responses then characterize these contributions in knockout mice lacking rod transducin-α (Trα), or certain pathway components associated with subsets of rod pathways. These comparisons reveal that rod pathway driven light sensitivity in retinal ganglion cells (RGCs) is entirely dependent on Trα, but partially independent of connexin 36 (Cx36) and rod bipolar cells. Pharmacological experiments show that rod pathway-driven and Cx36-independent RGC ON responses are also metabotropic glutamate receptor 6-dependent. To validate the RGC findings in awake, behaving animals we measured optokinetic reflexes (OKRs), which are sensitive to changes in ON pathways. Scotopic OKR contrast sensitivity was lost in Trα(-/-) mice, but indistinguishable from controls in Cx36(-/-) and rod bipolar cell knockout mice. Mesopic OKRs were also altered in mutant mice: Trα(-/-) mice had decreased spatial acuity, rod BC knockouts had decreased sensitivity, and Cx36(-/-) mice had increased sensitivity. These results provide compelling evidence against the complete Cx36 or rod BC dependence of night vision's ON component. Further, the findings suggest the parallel nature of rod pathways provides considerable redundancy to scotopic light sensitivity but distinct contributions to mesopic responses through complicated interactions with cone pathways. PMID:26718442

  11. Feasibility study of the University of Utah TRIGA reactor power upgrade in respect to control rod system

    NASA Astrophysics Data System (ADS)

    Cutic, Avdo

    The objectives of this thesis are twofold: to determine the highest achievable power levels of the current University of Utah TRIG Reactor (UUTR) core configuration with the existing three control rods, and to design the core for higher reactor power by optimizing the control rod worth. For the current core configuration, the maximum reactor power, eigenvalue keff, shutdown margin, and excess reactivity have been measured and calculated. These calculated estimates resulted from thermal power calibrations, and the control rod worth measurements at various power levels. The results were then used as a benchmark to verify the MCNP5 core simulations for the current core and then to design a core for higher reactor power. This study showed that the maximum achievable power with the current core configuration and control rod system is 150kW, which is 50kW higher than the licensed power of the UUTR. The maximum achievable UUTR core power with the existing fuel is determined by optimizing the core configuration and control rod worth, showing that a power upgrade of 500 kW is achievable. However, it requires a new control rod system consisting of a total of four control rods. The cost of such an upgrade is $115,000.

  12. Measuring Sensory Reactivity in Autism Spectrum Disorder: Application and Simplification of a Clinician-Administered Sensory Observation Scale

    ERIC Educational Resources Information Center

    Tavassoli, Teresa; Bellesheim, Katherine; Siper, Paige M.; Wang, A. Ting; Halpern, Danielle; Gorenstein, Michelle; Grodberg, David; Kolevzon, Alexander; Buxbaum, Joseph D.

    2016-01-01

    Sensory reactivity is a new DSM-5 criterion for autism spectrum disorder (ASD). The current study aims to validate a clinician-administered sensory observation in ASD, the Sensory Processing Scale Assessment (SPS). The SPS and the Short Sensory Profile (SSP) parent-report were used to measure sensory reactivity in children with ASD (n = 35) and…

  13. Self-Reported Trait Mindfulness and Affective Reactivity: A Motivational Approach Using Multiple Psychophysiological Measures

    PubMed Central

    Cosme, Danielle; Wiens, Stefan

    2015-01-01

    As a form of attention, mindfulness is qualitatively receptive and non-reactive, and is thought to facilitate adaptive emotional responding. One suggested mechanism is that mindfulness facilitates disengagement from an affective stimulus and thereby decreases affective reactivity. However, mindfulness has been conceptualized as a state, intervention, and trait. Because evidence is mixed as to whether self-reported trait mindfulness decreases affective reactivity, we used a multi-method approach to study the relationship between individual differences in self-reported trait mindfulness and electrocortical, electrodermal, electromyographic, and self-reported responses to emotional pictures. Specifically, while participants (N = 51) passively viewed pleasant, neutral, and unpleasant IAPS pictures, we recorded high-density (128 channels) electrocortical, electrodermal, and electromyographic data to the pictures as well as to acoustic startle probes presented during the pictures. Afterwards, participants rated their subjective valence and arousal while viewing the pictures again. If trait mindfulness spontaneously reduces general emotional reactivity, then for individuals reporting high rather than low mindfulness, response differences between emotional and neutral pictures would show relatively decreased early posterior negativity (EPN) and late positive potential (LPP) amplitudes, decreased skin conductance responses, and decreased subjective ratings for valence and arousal. High mindfulness would also be associated with decreased emotional modulation of startle eyeblink and P3 amplitudes. Although results showed clear effects of emotion on the dependent measures, in general, mindfulness did not moderate these effects. For most measures, effect sizes were small with rather narrow confidence intervals. These data do not support the hypothesis that individual differences in self-reported trait mindfulness are related to spontaneous emotional responses during picture

  14. Self-reported trait mindfulness and affective reactivity: a motivational approach using multiple psychophysiological measures.

    PubMed

    Cosme, Danielle; Wiens, Stefan

    2015-01-01

    As a form of attention, mindfulness is qualitatively receptive and non-reactive, and is thought to facilitate adaptive emotional responding. One suggested mechanism is that mindfulness facilitates disengagement from an affective stimulus and thereby decreases affective reactivity. However, mindfulness has been conceptualized as a state, intervention, and trait. Because evidence is mixed as to whether self-reported trait mindfulness decreases affective reactivity, we used a multi-method approach to study the relationship between individual differences in self-reported trait mindfulness and electrocortical, electrodermal, electromyographic, and self-reported responses to emotional pictures. Specifically, while participants (N = 51) passively viewed pleasant, neutral, and unpleasant IAPS pictures, we recorded high-density (128 channels) electrocortical, electrodermal, and electromyographic data to the pictures as well as to acoustic startle probes presented during the pictures. Afterwards, participants rated their subjective valence and arousal while viewing the pictures again. If trait mindfulness spontaneously reduces general emotional reactivity, then for individuals reporting high rather than low mindfulness, response differences between emotional and neutral pictures would show relatively decreased early posterior negativity (EPN) and late positive potential (LPP) amplitudes, decreased skin conductance responses, and decreased subjective ratings for valence and arousal. High mindfulness would also be associated with decreased emotional modulation of startle eyeblink and P3 amplitudes. Although results showed clear effects of emotion on the dependent measures, in general, mindfulness did not moderate these effects. For most measures, effect sizes were small with rather narrow confidence intervals. These data do not support the hypothesis that individual differences in self-reported trait mindfulness are related to spontaneous emotional responses during picture

  15. Reproducibility of parameters of postocclusive reactive hyperemia measured by diffuse optical tomography

    NASA Astrophysics Data System (ADS)

    Vidal-Rosas, Ernesto E.; Billings, Stephen A.; Chico, Timothy; Coca, Daniel

    2016-06-01

    The application of near-infrared spectroscopy (NIRS) to assess microvascular function has shown promising results. An important limitation when using a single source-detector pair, however, is the lack of depth sensitivity. Diffuse optical tomography (DOT) overcomes this limitation using an array of sources and detectors that allow the reconstruction of volumetric hemodynamic changes. This study compares the key parameters of postocclusive reactive hyperemia measured in the forearm using standard NIRS and DOT. We show that while the mean parameter values are similar for the two techniques, DOT achieves much better reproducibility, as measured by the intraclass correlation coefficient (ICC). We show that DOT achieves high reproducibility for muscle oxygen consumption (ICC: 0.99), time to maximal HbO2 (ICC: 0.94), maximal HbO2 (ICC: 0.99), and time to maximal HbT (ICC: 0.99). Absolute reproducibility as measured by the standard error of measurement is consistently smaller and close to zero (ideal value) across all parameters measured by DOT compared to NIRS. We conclude that DOT provides a more robust characterization of the reactive hyperemic response and show how the availability of volumetric hemodynamic changes allows the identification of areas of temporal consistency, which could help characterize more precisely the microvasculature.

  16. Seasonal measurements of total OH reactivity fluxes, total ozone loss rates and missing emissions from Norway spruce in 2011

    NASA Astrophysics Data System (ADS)

    Nölscher, A. C.; Bourtsoukidis, E.; Bonn, B.; Kesselmeier, J.; Lelieveld, J.; Williams, J.

    2012-10-01

    Numerous reactive volatile organic compounds (VOCs) are emitted into the atmosphere by vegetation. Most biogenic VOCs are highly reactive towards the atmosphere's most important oxidant, the hydroxyl (OH) radical. One way to investigate the chemical interplay between biosphere and atmosphere is through the measurement of total OH reactivity, the total loss rate of OH radicals. This study presents the first determination of total OH reactivity emission rates (measurements via the Comparative Reactivity Method) based on a branch cuvette enclosure system mounted on a Norway spruce (Picea abies) throughout spring, summer and autumn 2011. In parallel separate VOC emission rates were monitored by a Proton Transfer Reaction-Mass Spectrometer (PTR-MS), and total ozone (O3) loss rates were obtained inside the cuvette. Total OH reactivity emission rates were in general temperature and light dependent, showing strong diel cycles with highest values during daytime. Monoterpene emissions contributed most, accounting for 56-69% of the measured total OH reactivity flux in spring and early summer. However, during late summer and autumn the monoterpene contribution decreased to 11-16%. At this time, a large missing fraction of the total OH reactivity emission rate (70-84%) was found when compared to the VOC budget measured by PTR-MS. Total OH reactivity and missing total OH reactivity emission rates reached maximum values in late summer corresponding to the period of highest temperature. Total O3 loss rates within the closed cuvette showed similar diel profiles and comparable seasonality to the total OH reactivity fluxes. Total OH reactivity fluxes were also compared to emissions from needle storage pools predicted by a temperature-only dependent algorithm. Deviations of total OH reactivity fluxes from the temperature-only dependent emission algorithm were observed for occasions of mechanical and heat stress. While for mechanical stress, induced by strong wind, measured VOCs could

  17. Measuring the biosphere-atmosphere exchange of total reactive nitrogen by eddy covariance

    NASA Astrophysics Data System (ADS)

    Ammann, C.; Wolff, V.; Marx, O.; Brümmer, C.; Neftel, A.

    2012-11-01

    The (net) exchange of reactive nitrogen (Nr) with the atmosphere is an important driver for ecosystem productivity and greenhouse gas exchange. The exchange of airborne Nr includes various trace compounds that usually require different specific measurement techniques, and up to now fast response instruments suitable for eddy covariance measurements are only available for few of these compounds. Here we present eddy covariance flux measurements with a recently introduced converter (TRANC) for the sum of all Nr compounds (∑Nr). Measurements were performed over a managed grassland field with phases of net emission and net deposition of ∑Nr and alternating dominance of oxidized (NOX) and reduced species (NH3). Spectral analysis of the eddy covariance data exhibited the existence of covariance function peaks at a reasonable time lag related to the sampling tube residence time under stationary conditions. Using ogive analysis, the high-frequency damping was quantified to 19%-26% for a low measurement height of 1.2 m and to about 10% for 4.8 m measurement height. ∑Nr concentrations and fluxes were compared to parallel NO and NO2 measurements by dynamic chambers and NH3 measurements by the aerodynamic gradient technique. The average concentration results indicate that the main compounds NO2 and NH3 were converted by the TRANC system with an efficiency of near 100%. With an optimised sample inlet also the fluxes of these compounds were recovered reasonably well including net deposition and net emission phases. The study shows that the TRANC system is suitable for fast response measurements of oxidized and reduced nitrogen compounds and can be used for continuous eddy covariance flux measurements of total reactive nitrogen.

  18. Control rod drive

    SciTech Connect

    Hawke, Basil C.

    1986-01-01

    A control rod drive uses gravitational forces to insert one or more control rods upwardly into a reactor core from beneath the reactor core under emergency conditions. The preferred control rod drive includes a vertically movable weight and a mechanism operatively associating the weight with the control rod so that downward movement of the weight is translated into upward movement of the control rod. The preferred control rod drive further includes an electric motor for driving the control rods under normal conditions, an electrically actuated clutch which automatically disengages the motor during a power failure and a decelerator for bringing the control rod to a controlled stop when it is inserted under emergency conditions into a reactor core.

  19. Measurements of fuel pin/water hole worths and power peaking, void coefficients, and temperature coefficients for 4. 81 wt% enriched UO[sub 2] fuel rods

    SciTech Connect

    Harris, D.R.; Rohr, R.R.; Angelo, P.L.; Patrou, N.T.; Buckwheat, K.W.; Hayes, D.K.

    1990-01-01

    The Rensselaer Polytechnic Institute reactor critical facility is currently the only facility in North America providing critical measurement data in support of the light water reactor electric power industry. The reactor is fueled by 4.81 wt% [sup 235]U enriched UO[sub 2] high-density pellets in stainless steel clad fuel rods at the present time, although experiments with other fuels are being analyzed. The fuel pins are supported by inexpensive stainless steel lattice plates in a large open water tank. Three sets of lattice plates have been fabricated for fuel pins in square array with pitches 0.585, 0.613, and 0.640 in. (1.486, 0.613, and 1.656 cm, respectively) to provide a relevant range of water-to-fuel volume ratios. The measurements reported here are for the first of these, a relatively tight lattice of considerable interest for reactor physics methods for advanced fuels and reactors.

  20. Measurement reactivity and fatigue effects in daily diary research with families.

    PubMed

    Reynolds, Bridget M; Robles, Theodore F; Repetti, Rena L

    2016-03-01

    Methodological challenges associated with measurement reactivity and fatigue were addressed using diary data collected from mothers (n = 47), fathers (n = 39), and children (n = 47; 8-13 years) across 56 consecutive days. Demonstrating the feasibility of extended diary studies with families, on-time compliance rates were upward of 90% for all family members, with only minor within-person declines in weekday compliance over time. Multilevel models revealed slight decreases in mother and father daily reports of parent-child conflict and warmth across days, suggesting possible measurement reactivity. Global perceptions of parent-child involvement, measured via a 1-time survey at baseline, moderated change in parent, but not child, diary reports of conflict and warmth. Finally, weakening agreement between mother and child diary reports of conflict and strengthening of positive within-person associations between child-reported negative mood and same-diary ratings of parent-child conflict indicate potential fatigue-related declines in response accuracy. Although generally minimal, observed measurement effects highlight the need for additional methodological research in the study of everyday family life. (PsycINFO Database Record PMID:26689757

  1. Simulated Performance of the Integrated Passive Neutron Albedo Reactivity and Self-Interrogation Neutron Resonance Densitometry Detector Designed for Spent Fuel Measurement at the Fugen Reactor in Japan

    SciTech Connect

    Ulrich, Timothy J. II; Lafleur, Adrienne M.; Menlove, Howard O.; Swinhoe, Martyn T.; Tobin, Stephen J.; Seya, Michio; Bolind, Alan M.

    2012-07-16

    An integrated nondestructive assay instrument, which combined the Passive Neutron Albedo Reactivity (PNAR) and the Self-Interrogation Neutron Resonance Densitometry (SINRD) techniques, is the research focus for a collaborative effort between Los Alamos National Laboratory (LANL) and the Japanese Atomic Energy Agency as part of the Next Generation Safeguard Initiative. We will quantify the anticipated performance of this experimental system in two physical environments: (1) At LANL we will measure fresh Low Enriched Uranium (LEU) assemblies for which the average enrichment can be varied from 0.2% to 3.2% and for which Gd laced rods will be included. (2) At Fugen we will measure spent Mixed Oxide (MOX-B) and LEU spent fuel assemblies from the heavy water moderated Fugen reactor. The MOX-B assemblies will vary in burnup from {approx}3 GWd/tHM to {approx}20 GWd/tHM while the LEU assemblies ({approx}1.9% initial enrichment) will vary from {approx}2 GWd/tHM to {approx}7 GWd/tHM. The estimated count rates will be calculated using MCNPX. These preliminary results will help the finalization of the hardware design and also serve a guide for the experiment. The hardware of the detector is expected to be fabricated in 2012 with measurements expected to take place in 2012 and 2013. This work is supported by the Next Generation Safeguards Initiative, Office of Nuclear Safeguards and Security, National Nuclear Security Administration.

  2. Piston rod seal

    DOEpatents

    Lindskoug, Stefan

    1984-01-01

    In a piston rod seal of the type comprising a gland through which the piston rod is passed the piston is provided with a sleeve surrounding the piston rod and extending axially so as to axially partly overlap the gland when the piston is in its bottom dead center position.

  3. Development of burnup dependent fuel rod model in COBRA-TF

    NASA Astrophysics Data System (ADS)

    Yilmaz, Mine Ozdemir

    The purpose of this research was to develop a burnup dependent fuel thermal conductivity model within Pennsylvania State University, Reactor Dynamics and Fuel Management Group (RDFMG) version of the subchannel thermal-hydraulics code COBRA-TF (CTF). The model takes into account first, the degradation of fuel thermal conductivity with high burnup; and second, the fuel thermal conductivity dependence on the Gadolinium content for both UO2 and MOX fuel rods. The modified Nuclear Fuel Industries (NFI) model for UO2 fuel rods and Duriez/Modified NFI Model for MOX fuel rods were incorporated into CTF and fuel centerline predictions were compared against Halden experimental test data and FRAPCON-3.4 predictions to validate the burnup dependent fuel thermal conductivity model in CTF. Experimental test cases from Halden reactor fuel rods for UO2 fuel rods at Beginning of Life (BOL), through lifetime without Gd2O3 and through lifetime with Gd 2O3 and a MOX fuel rod were simulated with CTF. Since test fuel rod and FRAPCON-3.4 results were based on single rod measurements, CTF was run for a single fuel rod surrounded with a single channel configuration. Input decks for CTF were developed for one fuel rod located at the center of a subchannel (rod-centered subchannel approach). Fuel centerline temperatures predicted by CTF were compared against the measurements from Halden experimental test data and the predictions from FRAPCON-3.4. After implementing the new fuel thermal conductivity model in CTF and validating the model with experimental data, CTF model was applied to steady state and transient calculations. 4x4 PWR fuel bundle configuration from Purdue MOX benchmark was used to apply the new model for steady state and transient calculations. First, one of each high burnup UO2 and MOX fuel rods from 4x4 matrix were selected to carry out single fuel rod calculations and fuel centerline temperatures predicted by CTF/TORT-TD were compared against CTF /TORT-TD /FRAPTRAN

  4. Measurements and computer modeling of fast ion emission from plasma accelerators of the rod plasma injector type

    NASA Astrophysics Data System (ADS)

    Malinowski, Karol; Sadowski, Marek J.; Skladnik-Sadowska, Elzbieta

    2014-05-01

    This paper reports on the results of experimental studies and computer simulations of the emission of fast ion streams from so-called rod plasma injectors (RPI). Various RPI facilities have been used at the National Centre for Nuclear Research (NCBJ) for basic plasma studies as well as for material engineering. In fact, the RPI facilities have been studied experimentally for many years, particularly at the Institute for Nuclear Sciences (now the NCBJ), and numerous experimental data have been collected. Unfortunately, the ion emission characteristics have so far not been explained theoretically in a satisfactory way. In this paper, in order to explain these characteristics, use was made of a single-particle model. Taking into account the stochastic character of the ion emission, we applied a Monte Carlo method. The performed computer simulations of a pinhole image and energy spectrum of deuterons emitted from RPI-IBIS, which were computed on the basis of the applied model, appeared to be in reasonable agreement with the experimental data.

  5. A monobromobimane-based assay to measure the pharmacokinetic profile of reactive sulphide species in blood

    PubMed Central

    Wintner, Edward A; Deckwerth, Thomas L; Langston, William; Bengtsson, Asa; Leviten, Dina; Hill, Paul; Insko, Michael A; Dumpit, Ronald; VandenEkart, Emily; Toombs, Christopher F; Szabo, Csaba

    2010-01-01

    Background and purpose: Hydrogen sulphide (H2S) is a labile, endogenous metabolite of cysteine, with multiple biological roles. The development of sulphide-based therapies for human diseases will benefit from a reliable method of quantifying H2S in blood and tissues. Experimental approach: Concentrations of reactive sulphide in saline and freshly drawn whole blood were quantified by reaction with the thio-specific derivatization agent monobromobimane, followed by reversed-phase fluorescence HPLC and/or mass spectrometry. In pharmacokinetic studies, male rats were exposed either to intravenous infusions of sodium sulphide or to H2S gas inhalation, and levels of available blood sulphide were measured. Levels of dissolved H2S/HS- were concomitantly measured using an amperometric sensor. Key results: Monobromobimane was found to rapidly and quantitatively derivatize sulphide in saline or whole blood to yield the stable small molecule sulphide dibimane. Extraction and quantification of this bis-bimane derivative were validated via reversed-phase HPLC separation coupled to fluorescence detection, and also by mass spectrometry. Baseline levels of sulphide in blood were in the range of 0.4–0.9 µM. Intravenous administration of sodium sulphide solution (2–20 mg·kg−1·h−1) or inhalation of H2S gas (50–400 ppm) elevated reactive sulphide in blood in a dose-dependent manner. Each 1 mg·kg−1·h−1 of sodium sulphide infusion into rats was found to be pharmacokinetically equivalent to approximately 30 ppm of H2S gas inhalation. Conclusions and implications: The monobromobimane derivatization method is a sensitive and reliable means to measure reactive sulphide species in whole blood. Using this method, we have established a bioequivalence between infused sodium sulphide and inhaled H2S gas. PMID:20590590

  6. Measurements of reactive nitrogen above the canopy of a South East Asian tropical rainforest

    NASA Astrophysics Data System (ADS)

    Moller, Sarah; Lee, James; Pike, Rachel; Reeves, Claire; Stewart, David

    2010-05-01

    The potential for NOx species to influence local chemistry is significant in remote tropical areas due to the high concentrations of both OH and volatile organic compounds and the low background NOx concentrations. It has been suggested that emissions from soil could be a major biogenic source of nitrogen oxides but fluxes from tropical areas are poorly quantified. To understand the potential influence of soil emissions we must understand the sources and sinks of NOx in the boundary layer above a forest canopy. Measurements of NO, NO2 and total reactive nitrogen (NOy) were made in an opening above a rainforest canopy at the Bukit Atur Global Atmosphere Watch station in Sabah, Borneo as part of the Oxidant and particle photochemical processes above a South-East Asian tropical rainforest (OP3) project. Measurements of total reactive nitrogen using a gold catalytic converter followed by chemiluminesence detection of the resulting NO are compared to individual measurements of different NOy species (NO, NO2, PAN, Alkyl nitrates, HNO3) in an attempt to understand the nitrogen chemistry occurring and to assess any outstanding contributions to the nitrogen budget. The ground measurements above the rainforest canopy are compared to measurements taken from an aircraft platform within the boundary layer and free troposphere above the rainforest. The aircraft measurements from within the boundary layer agree well with the ground-based measurements suggesting that these are representative of the boundary layer above a rainforest canopy. A box model containing a simple chemical mechanism was used to explore the ability of a simplified global model chemical mechanism to capture the chemistry occurring at this rainforest site with a view towards improving the ability of global models to predict important trace gas levels over tropical rainforest.

  7. CONTROL ROD DRIVE

    DOEpatents

    Chapellier, R.A.; Rogers, I.

    1961-06-27

    Accurate and controlled drive for the control rod is from an electric motor. A hydraulic arrangement is provided to balance a piston against which a control rod is urged by the application of fluid pressure. The electric motor drive of the control rod for normal operation is made through the aforementioned piston. In the event scramming is required, the fluid pressure urging the control rod against the piston is relieved and an opposite fluid pressure is applied. The lack of mechanical connection between the electric motor and control rod facilitates the scramming operation.

  8. CRUCIFORM CONTROL ROD JOINT

    DOEpatents

    Thorp, A.G. II

    1962-08-01

    An invention is described which relates to nuclear reactor control rod components and more particularly to a joint between cruciform control rod members and cruciform control rod follower members. In one embodiment this invention provides interfitting crossed arms at adjacent ends of a control rod and its follower in abutting relation. This holds the members against relative opposite longitudinal movement while a compression member keys the arms against relative opposite rotation around a common axis. Means are also provided for centering the control rod and its follower on a common axis and for selectively releasing the control rod from its follower for the insertion of a replacement of the control rod and reuse of the follower. (AEC)

  9. TRANC - a novel fast-response converter to measure total reactive atmospheric nitrogen

    NASA Astrophysics Data System (ADS)

    Marx, O.; Brümmer, C.; Ammann, C.; Wolff, V.; Freibauer, A.

    2012-05-01

    The input and loss of plant available nitrogen (reactive nitrogen: Nr) from/to the atmosphere can be an important factor for the productivity of ecosystems and thus for its carbon and greenhouse gas exchange. We present a novel converter for reactive nitrogen (TRANC: Total Reactive Atmospheric Nitrogen Converter), which offers the opportunity to quantify the sum of all airborne reactive nitrogen compounds (∑Nr) in high time resolution. The basic concept of the TRANC is the full conversion of all Nr to nitrogen monoxide (NO) within two reaction steps. Initially, reduced Nr compounds are being oxidised, and oxidised Nr compounds are thermally converted to lower oxidation states. Particulate Nr is being sublimated and oxidised or reduced afterwards. In a second step, remaining higher nitrogen oxides or those generated in the first step are catalytically converted to NO with carbon monoxide used as reduction gas. The converter is combined with a fast response chemiluminescence detector (CLD) for NO analysis and its performance was tested for the most relevant gaseous and particulate Nr species under both laboratory and field conditions. Recovery rates during laboratory tests for NH3 and NO2 were found to be 95 and 99%, respectively, and 97% when the two gases were combined. In-field longterm stability over an 11-month period was approved by a value of 91% for NO2. Effective conversion was also found for ammonium and nitrate containing particles. The recovery rate of total ambient Nr was tested against the sum of individual measurements of NH3, HNO3, HONO, NH4+, NO3-, and NOx using a combination of different well-established devices. The results show that the TRANC-CLD system precisely captures fluctuations in ∑Nr concentrations and also matches the sum of all individual Nr compounds measured by the different single techniques. The TRANC features a specific design with very short distance between the sample air inlet and the place where the thermal and catalytic

  10. Using reactive strength index-modified as an explosive performance measurement tool in Division I athletes.

    PubMed

    Suchomel, Timothy J; Bailey, Christopher A; Sole, Christopher J; Grazer, Jacob L; Beckham, George K

    2015-04-01

    The purposes of this study included examining the reliability of reactive strength index-modified (RSImod), the relationships between RSImod and force-time variables, and the differences in RSImod between male and female collegiate athletes. One hundred six Division I collegiate athletes performed unloaded and loaded countermovement jumps (CMJs). Intraclass correlation coefficients and typical error expressed as a coefficient of variation were used to establish the relative and absolute reliability of RSImod, respectively. Pearson zero-order product-moment correlation coefficients were used to examine the relationships between RSImod and rate of force development, peak force (PF), and peak power (PP) during unloaded and loaded jumping conditions. Finally, independent samples t-tests were used to examine the sex differences in RSImod between male and female athletes. Intraclass correlation coefficient values for RSImod ranged from 0.96 to 0.98, and typical error values ranged from 7.5 to 9.3% during all jumping conditions. Statistically significant correlations existed between RSImod and all force-time variables examined for male and female athletes during both jumping conditions (p ≤ 0.05). Statistically significant differences in RSImod existed between male and female athletes during both unloaded and loaded CMJs (p < 0.001). Reactive strength index-modified seems to be a reliable performance measurement in male and female athletes. Reactive strength index-modified may be described and used as a measure of explosiveness. Stronger relationships between RSImod, PF, and PP existed in female athletes as compared with that in male athletes; however, further evidence investigating these relationships is needed before conclusive statements can be made. Male athletes produced greater RSImod values as compared with that produced by female athletes. PMID:25426515

  11. The directional sensitivity of retinal rods.

    PubMed Central

    Alpern, M; Ching, C C; Kitahara, K

    1983-01-01

    Rod field sensitivity, 10-S(r) (i.e. the reciprocal of the radiance of a background required for 10-fold elevation of rod threshold) was measured for monochromatic backgrounds traversing the pupil at various points (r) on three subjects. The wave-length dependency of the directional sensitivities of the three foveal cone mechanisms of the principal subject have been reported previously (Alpern & Kitahara, 1983). Rods, as cones, are less sensitive to obliquely incident, than to normally incident backgrounds. At the pupil margin (4 mm) the effect is between 0.368 and 0.976 log10 units smaller for rods. After correction for losses by corneal reflexion and by absorption in the lens, S(r) for rods is reasonably described by the parabolic equation used by Stiles (1937) to quantify the directional sensitivity of cones. The small effect for rods precludes a description as consistently precise as this equation provides for cones. The steepness of the parabolic curve best fitting the directional sensitivity data of the rods of the principal subject was independent of background wave number. For a second subject, whose rods are supposed to be smaller, it was directly proportional to the square of that wave number. The latter is the expectation if the directional sensitivity of this subject's rods were determined by principles outlined in the diffraction theory of Simon (1970). PMID:6644624

  12. Reactivity of Dogs' Brain Oscillations to Visual Stimuli Measured with Non-Invasive Electroencephalography

    PubMed Central

    Kujala, Miiamaaria V.; Törnqvist, Heini; Somppi, Sanni; Hänninen, Laura; Krause, Christina M.; Vainio, Outi; Kujala, Jan

    2013-01-01

    Studying cognition of domestic dogs has gone through a renaissance within the last decades. However, although the behavioral studies of dogs are beginning to be common in the field of animal cognition, the neural events underlying cognition remain unknown. Here, we employed a non-invasive electroencephalography, with adhesive electrodes attached to the top of the skin, to measure brain activity of from 8 domestic dogs (Canis familiaris) while they stayed still to observe photos of dog and human faces. Spontaneous oscillatory activity of the dogs, peaking in the sensors over the parieto-occipital cortex, was suppressed statistically significantly during visual task compared with resting activity at the frequency of 15–30 Hz. Moreover, a stimulus-induced low-frequency (∼2–6 Hz) suppression locked to the stimulus onset was evident at the frontal sensors, possibly reflecting a motor rhythm guiding the exploratory eye movements. The results suggest task-related reactivity of the macroscopic oscillatory activity in the dog brain. To our knowledge, the study is the first to reveal non-invasively measured reactivity of brain electrophysiological oscillations in healthy dogs, and it has been based purely on positive operant conditional training, without the need for movement restriction or medication. PMID:23650504

  13. Reactive ion etching-assisted surface-enhanced Raman scattering measurements on the single nanoparticle level

    SciTech Connect

    Wang, Si-Yi; Jiang, Xiang-Xu; Wei, Xin-Pan; Lee, Shuit-Tong E-mail: yaohe@suda.edu.cn; He, Yao E-mail: yaohe@suda.edu.cn; Xu, Ting-Ting

    2014-06-16

    Single-nanoparticle surface-enhanced Raman scattering (SERS) measurement is of essential importance for both fundamental research and practical applications. In this work, we develop a class of single-particle SERS approaches, i.e., reactive ion etching (RIE)-assisted SERS measurements correlated with scanning electron microscopy (SEM) strategy (RIE/SERS/SEM), enabling precise and high-resolution identification of single gold nanoparticle (AuNP) in facile and reliable manners. By using AuNP-coated silicon wafer and quartz glass slide as models, we further employ the developed RIE/SERS/SEM method for interrogating the relationship between SERS substrates and enhancement factor (EF) on the single particle level. Together with theoretical calculation using an established finite-difference-time-domain (FDTD) method, we demonstrate silicon wafer as superior SERS substrates, facilitating improvement of EF values.

  14. End-of-life nondestructive examination of Light Water Breeder Reactor fuel rods (LWBR Development Program)

    SciTech Connect

    Gorscak, D.A.; Campbell, W.R.; Clayton, J.C.

    1987-10-01

    In-bundle and out-of-bundle (single rod) nondestructive examinations of Light Water Breeder Reactor fuel rods were performed. In-bundle examinations included visual examination and measurement of rod bow, rod-to-rod gaps, and rod removal forces. Out-of-bundle examinations included rod visuals and measurement of fuel rod length, diameter and ovality, cladding oxide and crud thickness, support grid induced cladding wear mark depth and volume, and fuel rod free hanging bow. The out-of-bundle examination also included ultrasonic inspection for cladding defects, neutron radiography for pellet integrity and plenum gap measurements, and gamma scans for instack axial gap screening and binary fuel stack length measurements. The measurements confirmed design predictions of fuel rod performance and provided evidence of excellent fuel rod performance for operation of Light Water Breeder Reactor to 29,047 effective full power hours (EFPH).

  15. TRANC - a novel fast-response converter to measure total reactive atmospheric nitrogen

    NASA Astrophysics Data System (ADS)

    Marx, O.; Brümmer, C.; Ammann, C.; Wolff, V.; Freibauer, A.

    2011-12-01

    The input and loss of plant available nitrogen (N) from/to the atmosphere can be an important factor for the productivity of ecosystems and thus for its carbon and greenhouse gas exchange. We present a novel converter for the measurement of total reactive nitrogen (TRANC: Total Reactive Atmospheric Nitrogen Converter), which offers the opportunity to quantify the sum of all airborne reactive nitrogen (Nr) compounds in high time resolution. The basic concept of the TRANC is the full conversion of total Nr to nitrogen monoxide (NO) within two reaction steps. Initially, reduced N compounds are being oxidised, and oxidised N compounds are thermally converted to lower oxidation states. Particulate N is being sublimated and oxidised or reduced afterwards. In a second step, remaining higher N oxides or those originated in the first step are catalytically converted to NO with carbon monoxide used as reduction gas. The converter is combined with a fast response chemiluminescence detector (CLD) for NO analysis and its performance was tested for the most relevant gaseous and particulate Nr species under both laboratory and field conditions. Recovery rates during laboratory tests for NH3 and NO2 were found to be 95 and 99%, respectively, and 97% when the two gases were combined. In-field longterm stability over an 11-month period was approved by a value of 91% for NO2. Effective conversion was also found for ammonium and nitrate containing particles. The recovery rate of total ambient Nr was tested against the sum of individual measurements of NH3, HNO3, HONO, NH4+, NO3-, and NOx using a combination of different well-established devices. The results show that the TRANC-CLD system precisely captures fluctuations in Nr concentrations and also matches the sum of all Nr compounds measured by the different single techniques. The TRANC features a specific design with very short distance between the sample air inlet and the place where the thermal and catalytic conversions to NO

  16. Atmospheric and ocean measurements of reactive organic species from the Tropical Atlantic ocean.

    NASA Astrophysics Data System (ADS)

    Williams, J.; Holzinger, R.; Gros, V.; Hofmann, R.; Xu, X.; Wallace, D.

    2003-04-01

    Reactive organic species play an important role in the chemistry of the atmosphere. Large uncertainties exist in how the ocean influences the global budgets of reactive organic species. The first German SOLAS cruise M55 carried instrumentation to measure a range of organic species in the atmosphere and ocean surface layer. Between 12th October and 15th November the research vessel Meteor steamed from Curacao to Cameroon approximately along 10^o N. Approximately mid-Atlantic the ship performed two transects (N-S and S-N) reaching the equator and crossing the ITCZ twice. An assessment will be given of the organics over the Tropical Atlantic including data from 2 PTR-MS systems (air and water), canister air collection followed by GC-MS analysis, cartridge collection followed by 2D-GC-FID analysis, as well as ozone and CO instruments. The prevailing wind was easterly at all times so that air with decreasing extents of ocean contact time was encountered during the crossing. Longitudinal and interhemispheric gradients of organic species will be presented.

  17. Long term Suboxone™ emotional reactivity as measured by automatic detection in speech.

    PubMed

    Hill, Edward; Han, David; Dumouchel, Pierre; Dehak, Najim; Quatieri, Thomas; Moehs, Charles; Oscar-Berman, Marlene; Giordano, John; Simpatico, Thomas; Barh, Debmalya; Blum, Kenneth

    2013-01-01

    Addictions to illicit drugs are among the nation's most critical public health and societal problems. The current opioid prescription epidemic and the need for buprenorphine/naloxone (Suboxone®; SUBX) as an opioid maintenance substance, and its growing street diversion provided impetus to determine affective states ("true ground emotionality") in long-term SUBX patients. Toward the goal of effective monitoring, we utilized emotion-detection in speech as a measure of "true" emotionality in 36 SUBX patients compared to 44 individuals from the general population (GP) and 33 members of Alcoholics Anonymous (AA). Other less objective studies have investigated emotional reactivity of heroin, methadone and opioid abstinent patients. These studies indicate that current opioid users have abnormal emotional experience, characterized by heightened response to unpleasant stimuli and blunted response to pleasant stimuli. However, this is the first study to our knowledge to evaluate "true ground" emotionality in long-term buprenorphine/naloxone combination (Suboxone™). We found in long-term SUBX patients a significantly flat affect (p<0.01), and they had less self-awareness of being happy, sad, and anxious compared to both the GP and AA groups. We caution definitive interpretation of these seemingly important results until we compare the emotional reactivity of an opioid abstinent control using automatic detection in speech. These findings encourage continued research strategies in SUBX patients to target the specific brain regions responsible for relapse prevention of opioid addiction. PMID:23874860

  18. Long Term Suboxone™ Emotional Reactivity As Measured by Automatic Detection in Speech

    PubMed Central

    Hill, Edward; Han, David; Dumouchel, Pierre; Dehak, Najim; Quatieri, Thomas; Moehs, Charles; Oscar-Berman, Marlene; Giordano, John; Simpatico, Thomas; Blum, Kenneth

    2013-01-01

    Addictions to illicit drugs are among the nation’s most critical public health and societal problems. The current opioid prescription epidemic and the need for buprenorphine/naloxone (Suboxone®; SUBX) as an opioid maintenance substance, and its growing street diversion provided impetus to determine affective states (“true ground emotionality”) in long-term SUBX patients. Toward the goal of effective monitoring, we utilized emotion-detection in speech as a measure of “true” emotionality in 36 SUBX patients compared to 44 individuals from the general population (GP) and 33 members of Alcoholics Anonymous (AA). Other less objective studies have investigated emotional reactivity of heroin, methadone and opioid abstinent patients. These studies indicate that current opioid users have abnormal emotional experience, characterized by heightened response to unpleasant stimuli and blunted response to pleasant stimuli. However, this is the first study to our knowledge to evaluate “true ground” emotionality in long-term buprenorphine/naloxone combination (Suboxone™). We found in long-term SUBX patients a significantly flat affect (p<0.01), and they had less self-awareness of being happy, sad, and anxious compared to both the GP and AA groups. We caution definitive interpretation of these seemingly important results until we compare the emotional reactivity of an opioid abstinent control using automatic detection in speech. These findings encourage continued research strategies in SUBX patients to target the specific brain regions responsible for relapse prevention of opioid addiction. PMID:23874860

  19. Differentiating Challenge Reactivity from Psychomotor Activity in Studies of Children's Psychophysiology: Considerations for Theory and Measurement

    ERIC Educational Resources Information Center

    Bush, Nicole R.; Alkon, Abbey; Obradovic, Jelena; Stamperdahl, Juliet; Boyce, W. Thomas

    2011-01-01

    Current methods of assessing children's physiological "stress reactivity" may be confounded by psychomotor activity, biasing estimates of the relation between reactivity and health. We examined the joint and independent contributions of psychomotor activity and challenge reactivity during a protocol for 5- and 6-year-old children (N = 338).…

  20. Observational, Physiological, and Self-Report Measures of Children's Anger: Relations to Reactive versus Proactive Aggression.

    ERIC Educational Resources Information Center

    Hubbard, Julie A.; Smithmyer, Catherine M.; Ramsden, Sally R.; Parker, Elizabeth H.; Flanagan, Kelly D.; Dearing, Karen F.; Relyea, Nicole; Simons, Robert F.

    2002-01-01

    This study examined relations of reactive versus proactive aggression to second-graders' anger after losing in a board game to a cheating confederate. Found that reactive aggression, but not proactive aggression, was positively related to skin conductance reactivity and observed angry nonverbal behaviors, both at an aggregated level and in terms…

  1. The Perceived Stress Reactivity Scale: Measurement Invariance, Stability, and Validity in Three Countries

    ERIC Educational Resources Information Center

    Schlotz, Wolff; Yim, Ilona S.; Zoccola, Peggy M.; Jansen, Lars; Schulz, Peter

    2011-01-01

    There is accumulating evidence that individual differences in stress reactivity contribute to the risk for stress-related disease. However, the assessment of stress reactivity remains challenging, and there is a relative lack of questionnaires reliably assessing this construct. We here present the Perceived Stress Reactivity Scale (PSRS), a…

  2. CONTROL ROD DRIVE

    DOEpatents

    Chapellier, R.A.

    1960-05-24

    BS>A drive mechanism was invented for the control rod of a nuclear reactor. Power is provided by an electric motor and an outside source of fluid pressure is utilized in conjunction with the fluid pressure within the reactor to balance the loadings on the motor. The force exerted on the drive mechanism in the direction of scramming the rod is derived from the reactor fluid pressure so that failure of the outside pressure source will cause prompt scramming of the rod.

  3. Pull rod assembly

    DOEpatents

    Cioletti, O.C.

    1988-04-21

    A pull rod assembly comprising a pull rod having three peripheral grooves, a piston device including an adaptor ring and a seal ring, said piston device being mounted on the pull rod by a split ring retainer situated in one groove and extending into an interior groove in the adaptor and a resilient split ring retained in another groove and positioned to engage the piston device and to retain the seal on its adaptor.

  4. Rod Has High Tensile Strength And Low Thermal Expansion

    NASA Technical Reports Server (NTRS)

    Smith, D. E.; Everton, R. L.; Howe, E.; O'Malley, M.

    1996-01-01

    Thoriated tungsten extension rod fabricated to replace stainless-steel extension rod attached to linear variable-differential transformer in gap-measuring gauge. Threads formed on end of rod by machining with special fixtures and carefully chosen combination of speeds and feeds.

  5. Measurements of nitric oxide and total reactive nitrogen in the Antarctic stratosphere: Observations and chemical implications

    SciTech Connect

    Fahey, D.W.; Kelly, K.K. ); Murphy, D.M.; Proffitt, M.H.; Eubank, C.S. Univ. of Colorado, Boulder ); Ko, M.K.W. ); Ferry, G.V.; Lowenstein, M.; Chan, K.R. )

    1989-11-30

    Measurements of NO and the sum of reactive nitrogen species, NO{sub y}, were made as part of the Airborne Antarctic Ozone Experiment (AAOE) on flights of the NASA ER-2 aircraft over the Antarctic continent. Reactive nitrogen species include NO,NO{sub 2}, NO{sub 3}, N{sub 2}O{sub 5}, HNO{sub 3}, and ClONO{sub 2}. The technique utilized the conversion of NO{sub y} components to NO on a gold catalyst and the subsequent detection of NO by the chemiluminescent reaction of NO with O{sub 3}. NO was measured on two of the flights by removing the catalyst from the sample line. The boundary of a chemically perturbed region (CPR) above the continent occurred on average near 66{degree}S as indicated by a sharp increase in the level of ClO. Outside or equatorward of the CPR, NO{sub y} mixing ratios ranged between 6 and 12 parts per billion by volume (ppbv), with values increasing with latitude. At the edge of the CPR, large latitude gradients of NO{sub y}and NO were found with values decreasing poleward. Total NO{sub y} levels dropped to 4 ppbv or less within 5{degree} poleward of the boundary. NO values were 0.1-0.2 ppbv outside and below the detection limit of 0.03 ppbv inside the CPR. The levels of NO and NO{sub y} observed preclude a chemical loss of ozone due to reaction with NO.

  6. Comparison of cerebral vascular reactivity measures obtained using breath-holding and CO2 inhalation.

    PubMed

    Tancredi, Felipe B; Hoge, Richard D

    2013-07-01

    Stimulation of cerebral vasculature using hypercapnia has been widely used to study cerebral vascular reactivity (CVR), which can be expressed as the quantitative change in cerebral blood flow (CBF) per mm Hg change in end-tidal partial pressure of CO2 (PETCO2). We investigate whether different respiratory manipulations, with arterial spin labeling used to measure CBF, lead to consistent measures of CVR. The approaches included: (1) an automated system delivering variable concentrations of inspired CO2 for prospective targeting of PETCO2, (2) administration of a fixed concentration of CO2 leading to subject-dependent changes in PETCO2, (3) a breath-hold (BH) paradigm with physiologic modeling of CO2 accumulation, and (4) a maneuver combining breath-hold and hyperventilation. When CVR was expressed as the percent change in CBF per mm Hg change in PETCO2, methods 1 to 3 gave consistent results. The CVR values using method 4 were significantly lower. When CVR was expressed in terms of the absolute change in CBF (mL/100 g per minute per mm Hg), greater discrepancies became apparent: methods 2 and 3 gave lower absolute CVR values compared with method 1, and the value obtained with method 4 was dramatically lower. Our findings indicate that care must be taken to ensure that CVR is measured over the linear range of the CBF-CO2 dose-response curve, avoiding hypocapnic conditions. PMID:23571282

  7. A transparent Pyrex μ-reactor for combined in situ optical characterization and photocatalytic reactivity measurements

    SciTech Connect

    Dionigi, F.; Hansen, O.; Nielsen, M. G.; Chorkendorff, I.; Vesborg, P. C. K.; Pedersen, T.

    2013-10-15

    A new Pyrex-based μ-reactor for photocatalytic and optical characterization experiments is presented. The reactor chamber and gas channels are microfabricated in a thin poly-silicon coated Pyrex chip that is sealed with a Pyrex lid by anodic bonding. The device is transparent to light in the UV-vis-near infrared range of wavelengths (photon energies between ∼0.4 and ∼4.1 eV). The absorbance of a photocatalytic film obtained with a light transmission measurement during a photocatalytic reaction is presented as a proof of concept of a photocatalytic reactivity measurement combined with in situ optical characterization. Diffuse reflectance measurements of highly scattering photocatalytic nanopowders in a sealed Pyrex μ-reactor are also possible using an integrating sphere as shown in this work. These experiments prove that a photocatalyst can be characterized with optical techniques after a photocatalytic reaction without removing the material from the reactor. The catalyst deposited in the cylindrical reactor chamber can be illuminated from both top and bottom sides and an example of application of top and bottom illumination is presented.

  8. A transparent Pyrex μ-reactor for combined in situ optical characterization and photocatalytic reactivity measurements

    NASA Astrophysics Data System (ADS)

    Dionigi, F.; Nielsen, M. G.; Pedersen, T.; Hansen, O.; Chorkendorff, I.; Vesborg, P. C. K.

    2013-10-01

    A new Pyrex-based μ-reactor for photocatalytic and optical characterization experiments is presented. The reactor chamber and gas channels are microfabricated in a thin poly-silicon coated Pyrex chip that is sealed with a Pyrex lid by anodic bonding. The device is transparent to light in the UV-vis-near infrared range of wavelengths (photon energies between ˜0.4 and ˜4.1 eV). The absorbance of a photocatalytic film obtained with a light transmission measurement during a photocatalytic reaction is presented as a proof of concept of a photocatalytic reactivity measurement combined with in situ optical characterization. Diffuse reflectance measurements of highly scattering photocatalytic nanopowders in a sealed Pyrex μ-reactor are also possible using an integrating sphere as shown in this work. These experiments prove that a photocatalyst can be characterized with optical techniques after a photocatalytic reaction without removing the material from the reactor. The catalyst deposited in the cylindrical reactor chamber can be illuminated from both top and bottom sides and an example of application of top and bottom illumination is presented.

  9. Predicting Outcome of Childhood Bacterial Meningitis With a Single Measurement of C-Reactive Protein

    PubMed Central

    Peltola, Heikki; Roine, Irmeli; Cruzeiro, Manuel Leite; Bernardino, Luis

    2016-01-01

    Introduction: C-reactive protein (CRP), a marker of inflammation, shows high serum levels in invasive bacterial infections. We investigated the potential of a single CRP measurement at different phases of acute childhood bacterial meningitis to predict outcomes. Methods: Using whole-blood finger-prick samples with no centrifugation, CRP was measured quantitatively on arrival and on day 3 or 4 in children participating in 2 prospective, randomized, double-blind treatment studies conducted in Latin America or Angola. The results were compared with patient outcomes. Results: Although initial CRP values from 669 children gave useful prognostic information, the 3rd or 4th day measurements taken from 275 children associated significantly with seizures, slow recovery and low scores on the Glasgow Outcome Scale, with odds ratios for CRP values above the median (62 mg/L) ranging from 2 to 6, 2 to 5, and 3 to 5 (Latin America–Angola), respectively. Hearing impairment, although not full deafness, was 3 to 7 times more likely if CRP was above the median soon after hospitalization. Conclusions: Especially in resource-poor settings, clinicians have few simple-enough tools to identify the child with meningitis who requires maximum attention. CRP is a worthy addition. PMID:26986770

  10. What You Find Depends on How You Measure It: Reactivity of Response Scales Measuring Predecisional Information Distortion in Medical Diagnosis.

    PubMed

    Nurek, Martine; Kostopoulou, Olga

    2016-01-01

    "Predecisional information distortion" occurs when decision makers evaluate new information in a way that is biased towards their leading option. The phenomenon is well established, as is the method typically used to measure it, termed "stepwise evolution of preference" (SEP). An inadequacy of this method has recently come to the fore: it measures distortion as the total advantage afforded a leading option over its competitor, and therefore it cannot differentiate between distortion to strengthen a leading option ("proleader" distortion) and distortion to weaken a trailing option ("antitrailer" distortion). To address this, recent research introduced new response scales to SEP. We explore whether and how these new response scales might influence the very proleader and antitrailer processes that they were designed to capture ("reactivity"). We used the SEP method with concurrent verbal reporting: fifty family physicians verbalized their thoughts as they evaluated patient symptoms and signs ("cues") in relation to two competing diagnostic hypotheses. Twenty-five physicians evaluated each cue using the response scale traditional to SEP (a single response scale, returning a single measure of distortion); the other twenty-five did so using the response scales introduced in recent studies (two separate response scales, returning two separate measures of distortion: proleader and antitrailer). We measured proleader and antitrailer processes in verbalizations, and compared verbalizations in the single-scale and separate-scales groups. Response scales did not appear to affect proleader processes: the two groups of physicians were equally likely to bolster their leading diagnosis verbally. Response scales did, however, appear to affect antitrailer processes: the two groups denigrated their trailing diagnosis verbally to differing degrees. Our findings suggest that the response scales used to measure information distortion might influence its constituent processes, limiting

  11. FUEL ROD CLUSTERS

    DOEpatents

    Schultz, A.B.

    1959-08-01

    A cluster of nuclear fuel rods and a tubular casing therefor through which a coolant flows in heat-exchange contact with the fuel rods is described. The fuel rcds are held in the casing by virtue of the compressive force exerted between longitudinal ribs of the fuel rcds and internal ribs of the casing or the internal surfaces thereof.

  12. Magnetic switch for reactor control rod

    DOEpatents

    Germer, John H.

    1986-01-01

    A magnetic reed switch assembly for activating an electromagnetic grapple utilized to hold a control rod in position above a reactor core. In normal operation the magnetic field of a permanent magnet is short-circuited by a magnetic shunt, diverting the magnetic field away from the reed switch. The magnetic shunt is made of a material having a Curie-point at the desired release temperature. Above that temperature the material loses its ferromagnetic properties, and the magnetic path is diverted to the reed switch which closes and short-circuits the control circuit for the control rod electromagnetic grapple which allows the control rod to drop into the reactor core for controlling the reactivity of the core.

  13. Magnetic switch for reactor control rod. [LMFBR

    DOEpatents

    Germer, J.H.

    1982-09-30

    A magnetic reed switch assembly is described for activating an electromagnetic grapple utilized to hold a control rod in position above a reactor core. In normal operation the magnetic field of a permanent magnet is short-circuited by a magnetic shunt, diverting the magnetic field away from the reed switch. The magnetic shunt is made of a material having a Curie-point at the desired release temperature. Above that temperature the material loses its ferromagnetic properties, and the magnetic path is diverted to the reed switch which closes and short-circuits the control circuit for the control rod electro-magnetic grapple which allows the control rod to drop into the reactor core for controlling the reactivity of the core.

  14. Measurements of UV-generated free radicals/reactive oxygen species (ROS) in skin

    NASA Astrophysics Data System (ADS)

    Herrling, Th.; Jung, K.; Fuchs, J.

    2006-03-01

    Free radicals/reactive oxygen species (ROS) generated in skin by UV irradiation were measured by electron spin resonance (ESR). To increase the sensitivity of measurement the short life free radicals/ROS were scavenged and accumulated by using the nitroxyl probe 3-carboxy-2,2,5,5-tetrametylpyrrolidine-1-oxyl (PCA). The spatial distribution of free radicals/ROS measured in pig skin biopsies with ESR imaging after UV irradiation corresponds to the intensity decay of irradiance in the depth of the skin. The main part of free radicals/ROS were generated by UVA (320-400 nm) so that the spatial distribution of free radicals reaches up to the lower side of the dermis. In vivo measurements on human skin were performed with a L-band ESR spectrometer and a surface coil integrating the signal intensities from all skin layers to get a sufficient signal amplitude. Using this experimental arrangement the protection of UVB and UVA/B filter against the generation of free radicals/ROS in skin were measured. The protection against ROS and the repair of damages caused by them can be realized with active antioxidants characterized by a high antioxidative power (AP). The effect of UV filter and antioxidants corresponding to their protection against free radicals/ROS in skin generated by UVAB irradiation can be quantified by the new radical sun protection factor (RSF). The RSF indicates the increase of time for staying in the sun to generate the same number of free radicals/ROS in the skin like for the unprotected skin. Regarding the amount of generated free radicals/ROS in skin as an biophysical endpoint the RSF characterizes both the protection against UVB and UVA radiation.

  15. Rod Photoreceptors Detect Rapid Flicker

    ERIC Educational Resources Information Center

    Conner, J. D.; MacLeod, Donald I. A.

    1977-01-01

    Rod-isolation techniques show that light-adapted human rods detect flicker frequencies as high as 28 hertz, and that the function relating rod critical flicker frequency to stimulus intensity contains two distinct branches. (MLH)

  16. Regenerative hyperpolarization in rods.

    PubMed Central

    Werblin, F S

    1975-01-01

    1. The electrical properties of the rods in Necturus maculosus were studied at the cell body and the outer segments in dark and light under current and voltage clamp with a pair of intracellular electrodes separated by about 1 mum. 2. The membrane resistance in the dark was voltage- and time-dependent both for the cell body and the outer segment. Slight depolarizations in the cell body reduced the slope resistance from 60 to 10 M omega with a time constant of about 1 sec. Polarization in either direction, at the outer segment, when greater than about 20 mV, reduced the slope resistance from 60 to 30 M omega. The dark potential in the cell body was typically -30 to -35 m V; at the outer segment it was typically only -10 to -15 mV. 3. The light-elicited voltage response in both the cell body and the outer segment was largest with the membrane near the dark potential level. In both regions, the response was reduced when the membrane was polarized in either direction. 4. Under voltage-clamp conditions, a reversal potential for the light response near + 10 mV was measured at the outer segment. At the cell body no reversal potential for the light response was measured; there the clamping current required during the light response was almost of the same magnitude at all potential levels. 5. When the membrane at the cell body was hyperpolarized in the dark under voltage clamp, a transient outward current, typically about one-half the magnitude of the initial inward clamping current was required to maintain the membrane at the clamped potential level. This outward current transient was associated with a decrease in membrane resistance with similar time course. The transient outward current reversed and became inward when the membrane was clamped to potentials more negative than -80 mV. Thus, the transient outward current appears to involve a transient activation initiated by hyperpolarization. I is regenerative in that it is initiated by hyperpolarization and tends to

  17. Measurements of nitric oxide and total reactive nitrogen in the Antarctic stratosphere - Observations and chemical implications

    NASA Technical Reports Server (NTRS)

    Fahey, D. W.; Kelly, K. K.; Murphy, D. M.; Proffitt, M. H.; Eubank, C. S.; Ko, M. K. W.; Ferry, G. V.; Loewenstein, M.; Chan, K. R.

    1989-01-01

    Results are presented on measurements of NO and the sum of reactive nitrogen species, NO(y), which include NO, NO2, NO3, N2O5, HNO3, and ClONO2 (in addition to ClO, O3, H2O, and N2O measurements), obtained aboard the NASA ER-2 aircraft flying over the Antarctica between the latitudes of 53 and 72 deg S during the Airborne Antarctic Ozone Experiment. The boundary of the chemically perturbed region (CPR), as indicated by a sharp increase in the level of ClO, occurred near 66 deg S; outside or equatorward of the CPR, the NO(y) mixing ratios ranged between 6 and 12 ppbv, with values decreasing poleward and reaching total NO(y) levels of 4 ppbv or less within 5-deg poleward of the boundary. Data presented in this paper clearly associate the Antarctic ozone decrease with perturbed conditions of ClO, NO(y), and H2O, which are in turn associated with processes defined as nonstandard heterogeneous chemistry, denitrification, and dehydration, respectively.

  18. Measurements of total reactive nitrogen during the Airborne Arctic Stratospheric Expedition

    SciTech Connect

    Kawa, S.R.; Anderson, L.C. Univ. of Colorado, Boulder ); Fahey, D.W. ); Loewenstein, M.; Chan, K.R. )

    1990-03-01

    Composite distributions of measured total reactive nitrogen (NO{sub y}) from the NASA ER-2 during the Airborne Arctic Stratospheric Expedition (AASE) are presented. The observed features of these distributions are discussed in terms of the controlling dynamical, chemical, and microphysical processes. In the latitudinal profile from 58{degree}N to within about 4{degree} poleward of the polar vortex boundary, NO{sub y} conforms closely to predictions of NO{sub y} based on N{sub 2}O measurements. The features of the distribution are apparently dynamically controlled. Poleward of 5{degree} of latitude within the boundary, the average NO{sub y} decreases sharply and is significantly lower than that predicted from N{sub 2}O. This feature is consistent with loss of NO{sub y} through sedimentation of particles containing NO{sub y} in polar stratospheric clouds. The observed loss is not as systematic as in the Antarctic, consistent with the observed differences in season and meteorological conditions between the two campaigns.

  19. An Assay of Measuring Platelet Reactivity Using Monoclonal Antibody against Activated Platelet Glycoprotein IIb/IIIa in Patients Taking Clopidogrel

    PubMed Central

    Choi, Joon-Hyouk; Kim, Song-Yi; Kim, Ki-Seok; Kim, Young Ree; Kang, Sung Ha

    2015-01-01

    Background and Objectives Residual platelet reactivity in patients who are taking clopidogrel is commonly measured with VerifyNow assay, which is based on the principle of light transmission aggregometry. However, to evaluate the residual platelet reactivity, it would be more accurate if the reactivity of platelet glycoprotein (GP) IIb/IIIa is directly monitored. In this study, PAC1, a monoclonal antibody against activated platelet GP IIb/IIIa, was used to measure the residual platelet reactivity. Subjects and Methods Twenty seven patients with coronary artery disease taking clopidogrel were enrolled. Platelets in whole blood were stained with fluorescein isothiocyanate (FITC)-conjugated PAC1. Mean fluorescence intensity (MFI) and % positive platelets (PP) were measured with flow cytometry, and the binding index (BI; MFI × %PP/100) was calculated. P2Y12 reaction unit (PRU) and % inhibition of VerifyNow assay were also measured in the usual manner. Results PRU of VerifyNow assay correlated significantly with MFI, %PP, and BI at 10 µM (r=0.59, 0.73, and 0.60, respectively, all p<0.005) and 20 µM of adenosine diphosphate (ADP; r=0.61, 0.75, and 0.63, respectively, all p<0.005). The % inhibition also correlated significantly with MFI, %PP, and BI at 10 µM (r=-0.60, -0.69, and -0.59, respectively, all p<0.005) and 20 µM of ADP (r=-0.63, -0.71, and -0.62, respectively, all p<0.005). Conclusion Direct measurements of the reactivity of platelet GP IIb/IIIa were feasible using PAC1 and flow cytometry in patients taking clopidogrel. Further clinical studies are required to determine the cut-off values which would define high residual platelet reactivity in patients on this treatment protocol. PMID:26413105

  20. Monitoring shipping emissions with MAX-DOAS measurements of reactive trace gases

    NASA Astrophysics Data System (ADS)

    Wittrock, Folkard; Peters, Enno; Seyler, André; Kattner, Lisa; Mathieu-Üffing, Barbara; Burrows, John P.; Chirkov, Maksym; Meier, Andreas C.; Richter, Andreas; Schönhardt, Anja; Schmolke, Stefan; Theobald, Norbert

    2014-05-01

    Air pollution from ships contributes to overall air quality problems and it has direct health effects on the population in particular in coastal regions, and in harbor cities. In order to reduce the emissions the International Maritime Organisation (IMO) have tightened the regulations for air pollution. E.g. Sulfur Emission Control Areas (SECA) have been introduced where the sulfur content of marine fuel is limited. However, up to now there is no regular monitoring system available to verify that ships are complying with the new regulations. Furthermore measurements of reactive trace gases in marine environments are in general sparse. The project MeSMarT (Measurements of shipping emissions in the marine troposphere, www.mesmart.de) has been established as a cooperation between the University of Bremen and the German Bundesamt für Seeschifffahrt und Hydrographie (Federal Maritime and Hydrographic Agency) with support of the Helmholtz Research Centre Geesthacht to estimate the influence of ship emissions on the chemistry of the atmospheric boundary layer and to establish a monitoring system for main shipping routes. Here we present MAX-DOAS observations of NO2 and SO2 carried out during ship campaigns in the North and Baltic Sea and from two permanent sites close to the Elbe river (Wedel, Germany) and on the island Neuwerk close to the mouths of Elbe and Weser river. Mixing ratios of both trace gases have been retrieved using different approaches (pure geometric and taking into account the radiative transfer) and compared to in situ and air borne observations (see Kattner et al., Monitoring shipping emissions with in-situ measurements of trace gases, and Meier et al., Airborne measurements of NO2 shipping emissions using imaging DOAS) observations. Furthermore simple approaches have been used to calculate emission factors of NOx and SO2 for single ships.

  1. C-reactive protein and fibrin clot strength measured by thrombelastography after coronary stenting

    PubMed Central

    Kreutz, Rolf P.; Owens, Janelle; Breall, Jeffrey A.; Lu, Deshun; von der Lohe, Elisabeth; Bolad, Islam; Sinha, Anjan; Flockhart, David A.

    2014-01-01

    Inflammation is implicated in the progression of coronary artery disease and the molecular processes of inflammation and thrombosis are closely intertwined. Elevated levels of C-reactive protein (CRP) have been associated with an elevated risk of adverse ischaemic events after coronary stenting and hypercoagulability. Heightened whole blood clot strength measured by thrombelastography (TEG) has been associated with adverse ischaemic events after stenting. We intended to examine the relationship of CRP to plasma fibrin clot strength in patients after coronary stenting. Plasma fibrin clot strength was measured by TEG in 54 patients 16–24 h after undergoing elective percutaneous coronary intervention (PCI). Coagulation was induced in citrated plasma by addition of kaolin and CaCl2. Plasma levels of CRP and fibrinogen were measured by enzyme-linked immunoassay. Increasing quartiles of CRP were associated with increasing levels of maximal plasma fibrin clot strength measured by TEG (P < 0.001) and increasing BMI (P =0.04). Patients in the highest quartile of CRP had significantly higher maximal fibrin clot strength (G) than the patients in the lowest quartile (G: 3438 ± 623 vs. 2184 ± 576 dyn/cm2, P < 0.0001). Fibrinogen concentration was not significantly different across quartiles of CRP (P =0.97). Patients with established coronary artery disease undergoing coronary stenting who have elevated CRP after PCI exhibit heightened maximal plasma fibrin clot strength as compared with those with low CRP. Thrombotic risk associated with elevated CRP may be linked to procoagulant changes and high tensile fibrin clot strength independent of fibrinogen concentration. PMID:23429252

  2. Flux measurements of reactive nitrogen compounds using a chemiluminescence analyser with different converter types

    NASA Astrophysics Data System (ADS)

    Ammann, Christof; Wolff, Veronika

    2015-04-01

    The availability of reactive nitrogen (Nr) is a key limiting factors for the productivity and the competition success of individual species. On the other hand, certain nitrogenous compounds can also be emitted from natural or managed ecosystems. Thus the quantification of the Nr exchange can be essential for the interpretation of ecosystem behavior. For the observation of Nr dry deposition and emission the eddy covariance (EC) method is preferable since it does not modify the environmental conditions of the ecosystem, is less prone to wall effects than chamber methods, and is less affected by gas phase chemical reactions than gradient methods. Since the various Nr compounds can undergo fast chemical reactions and have differing chemical and physical characteristics, a variety of detection techniques is usually necessary that often cannot meet the fast response requirements of the EC technique. Here we show applications of a fast response 2-channel NO analyzer suitable for EC measurements. In combination with different inlet converters (photolytic converter, gold catalyst converter, and high-temperature steel converter), the system could alternatively be used for flux measurements of NO2, NOy, and total Nr. The quantification of By combining the 2-channel analyzer with the NOy and total Nr converter simultaneously, the NH3 flux could be determined from the difference between the two channels. Concentration and flux measurements of the system were verified by inter-comparison with other methods. Potential problems include the damping of high-frequency fluctuations in the inlet system. It is therefore important to place the converter close to the sampling inlet and to quantify and correct the damping effects. Moreover, like most other flux measurement techniques, the system is susceptible to non-stationary trace gas concentrations that often occur near pollution sources.

  3. C-reactive protein and fibrin clot strength measured by thrombelastography after coronary stenting.

    PubMed

    Kreutz, Rolf P; Owens, Janelle; Breall, Jeffrey A; Lu, Deshun; von der Lohe, Elisabeth; Bolad, Islam; Sinha, Anjan; Flockhart, David A

    2013-04-01

    Inflammation is implicated in the progression of coronary artery disease and the molecular processes of inflammation and thrombosis are closely intertwined. Elevated levels of C-reactive protein (CRP) have been associated with an elevated risk of adverse ischaemic events after coronary stenting and hypercoagulability. Heightened whole blood clot strength measured by thrombelastography (TEG) has been associated with adverse ischaemic events after stenting. We intended to examine the relationship of CRP to plasma fibrin clot strength in patients after coronary stenting. Plasma fibrin clot strength was measured by TEG in 54 patients 16-24 h after undergoing elective percutaneous coronary intervention (PCI). Coagulation was induced in citrated plasma by addition of kaolin and CaCl2. Plasma levels of CRP and fibrinogen were measured by enzyme-linked immunoassay. Increasing quartiles of CRP were associated with increasing levels of maximal plasma fibrin clot strength measured by TEG (P < 0.001) and increasing BMI (P = 0.04). Patients in the highest quartile of CRP had significantly higher maximal fibrin clot strength (G) than the patients in the lowest quartile (G: 3438 ± 623 vs. 2184 ± 576 dyn/cm, P < 0.0001). Fibrinogen concentration was not significantly different across quartiles of CRP (P = 0.97). Patients with established coronary artery disease undergoing coronary stenting who have elevated CRP after PCI exhibit heightened maximal plasma fibrin clot strength as compared with those with low CRP. Thrombotic risk associated with elevated CRP may be linked to procoagulant changes and high tensile fibrin clot strength independent of fibrinogen concentration. PMID:23429252

  4. New Directions in Measuring Reactive and Proactive Aggression: Validation of a Teacher Questionnaire

    ERIC Educational Resources Information Center

    Polman, Hanneke; de Castro, Bram Orobio; Thomaes, Sander; van Aken, Marcel

    2009-01-01

    The well-known distinction between reactive and proactive aggression is theoretically important but empirically controversial. Recently, aggression researchers have argued that we should separate the form and function of aggression to make a clearer distinction between reactive and proactive aggression. This article describes the validation of a…

  5. The effect of basal vasodilation on hypercapnic and hypocapnic reactivity measured using magnetic resonance imaging

    PubMed Central

    Bright, Molly G; Donahue, Manus J; Duyn, Jeff H; Jezzard, Peter; Bulte, Daniel P

    2011-01-01

    Cerebrovascular reactivity to vasodilatory hypercapnic and vasoconstrictive hypocapnic challenges is known to be altered in several hemodynamic disorders, which is often attributable to changes in smooth muscle-mediated vascular compliance. Recently, attenuated reactivity to hypercapnia but enhanced reactivity to hypocapnia was observed in patients with chronic stroke. We hypothesize that the latter observation could be explained by a change in the basal vascular tone. In particular, reduced cerebral perfusion pressure, as is prevalent in these patients, may cause vasodilation through autoregulatory mechanisms, and this compensatory baseline condition may alter reactivity to vasoconstrictive hypocapnic challenges. To test this hypothesis, a predilated vascular condition was created in young, healthy subjects (n=11; age=23 to 36 years) using inhalation of 4% CO2. Using blood oxygenation level-dependent functional magnetic resonance imaging at 3 T, breath holding and cued deep breathing respiratory challenges were administered to assess hypercapnia and hypocapnia reactivity, respectively. During the predilated condition, vasoconstrictive reactivity to hypocapnia was significantly (21.1%, P=0.016) enhanced throughout the gray matter, whereas there was no significant change (6.4%, P=0.459) in hypercapnic vasodilatory reactivity. This suggests that baseline vasodilation may explain the enhanced hypocapnia reactivity observed in some stroke patients, and that hypocapnia challenges may help identify the level of vascular compliance in patients with reduced cerebral perfusion pressure. PMID:20959855

  6. Fuel rod mechanical deformation during the PBF/LOFT lead rod loss-of-coolant experiments

    SciTech Connect

    Varacalle, Jr., D. J.; MacDonald, P. E.; Shiozawa, S.; Driskell, W. E.

    1980-01-01

    Results of four PBF/LOFT Lead Rod (LLR) sequential blowdown tests conducted in the Power Burst Facility (PBF) are presented. Each test employed four separately shrouded fuel rods. The primary objective of the test series was to evaluate the extent of mechanical deformation that would be expected to occur to low pressure (0.1 MPa), light water reactor design fuel rods when subjected to a series of double ended cold leg break loss-of-coolant accident (LOCA) tests, and to determine whether subjecting these deformed fuel rods to subsequent testing would result in rod failure. The extent of mechanical deformation (buckling, collapse, or waisting of the cladding) was evaluated by comparison of cladding temperature and system pressure measurements with out-of-pile experimental data, and by posttest visual examinations and cladding diametral measurements.

  7. Comparison of Reactive Mercury Concentrations Measured Simultaneously Using KCl-coated Denuders, Nylon Membranes, and Cation Exchange Membranes

    NASA Astrophysics Data System (ADS)

    Gustin, M. S.; Huang, J.; Miller, M. B.; Weiss-Penzias, P. S.

    2012-12-01

    There is much debate about the chemistry of reactive gaseous and particle bound mercury (Hg) in the atmosphere, and the processes associated with formation. In addition, there are concerns regarding the interferences and calibration of the widely used Tekran® 2537/1130/1135 Hg measurement system. To investigate these we developed simple laboratory and field sampling systems designed to collect and analyze reactive Hg (Hg (II), Hg (I) and/or particle bound). A manifold system was applied in the laboratory, and in the field, in-series and -parallel membranes, flow controllers and pumps were utilized. Both systems actively collected reactive Hg using nylon membranes and cation exchange membranes alongside measurements made using the Tekran® system. The analytical system consisted of step wise 2.5 minute thermo-desorption and Hg quantification by cold vapor atomic fluorescence. In the laboratory, we compared the efficiency of these surfaces for collection of HgO, HgCl2, and HgBr2 when permeated into Hg and oxidant free air, and ambient filtered air. Other tests are ongoing. Thus far, results show concentrations measured by the cation exchange membrane were two-to-three fold greater than that measured by the nylon membranes, and three-to -four fold greater than that measured by the KCl-coated annual denuder. Thermo-desorption profiles obtained using nylon membranes show slightly different patterns associated with the reactive Hg compounds as permeated and tested. Field measurements were made at two locations in Reno, Nevada (a high traffic site and an agricultural area) and at Elkhorn Slough, California (marine site). Desorption profiles from nylon membrane differed by site and by time of year. Although the influence of aerosol on this measurement has not been explored, field results suggest different forms of reactive Hg were present in the atmosphere as a function of season and location.

  8. A High Precision Method for Quantitative Measurements of Reactive Oxygen Species in Frozen Biopsies

    PubMed Central

    Lindgren, Mikael; Gustafsson, Håkan

    2014-01-01

    Objective An electron paramagnetic resonance (EPR) technique using the spin probe cyclic hydroxylamine 1-hydroxy-3-methoxycarbonyl-2,2,5,5-tetramethylpyrrolidine (CMH) was introduced as a versatile method for high precision quantification of reactive oxygen species, including the superoxide radical in frozen biological samples such as cell suspensions, blood or biopsies. Materials and Methods Loss of measurement precision and accuracy due to variations in sample size and shape were minimized by assembling the sample in a well-defined volume. Measurement was carried out at low temperature (150 K) using a nitrogen flow Dewar. The signal intensity was measured from the EPR 1st derivative amplitude, and related to a sample, 3-carboxy-proxyl (CP•) with known spin concentration. Results The absolute spin concentration could be quantified with a precision and accuracy better than ±10 µM (k = 1). The spin concentration of samples stored at −80°C could be reproduced after 6 months of storage well within the same error estimate. Conclusion The absolute spin concentration in wet biological samples such as biopsies, water solutions and cell cultures could be quantified with higher precision and accuracy than normally achievable using common techniques such as flat cells, tissue cells and various capillary tubes. In addition; biological samples could be collected and stored for future incubation with spin probe, and also further stored up to at least six months before EPR analysis, without loss of signal intensity. This opens for the possibility to store and transport incubated biological samples with known accuracy of the spin concentration over time. PMID:24603936

  9. Strain measurement in a concrete beam by use of the Brillouin-scattering-based distributed fiber sensor with single-mode fibers embedded in glass fiber reinforced polymer rods and bonded to steel reinforcing bars.

    PubMed

    Zeng, Xiaodong; Bao, Xiaoyi; Chhoa, Chia Yee; Bremner, Theodore W; Brown, Anthony W; DeMerchant, Michael D; Ferrier, Graham; Kalamkarov, Alexander L; Georgiades, Anastasis V

    2002-08-20

    The strain measurement of a 1.65-m reinforced concrete beam by use of a distributed fiber strain sensor with a 50-cm spatial resolution and 5-cm readout resolution is reported. The strain-measurement accuracy is +/-15 microepsilon (microm/m) according to the system calibration in the laboratory environment with non-uniform-distributed strain and +/-5 microepsilon with uniform strain distribution. The strain distribution has been measured for one-point and two-point loading patterns for optical fibers embedded in pultruded glass fiber reinforced polymer (GFRP) rods and those bonded to steel reinforcing bars. In the one-point loading case, the strain deviations are +/-7 and +/-15 microepsilon for fibers embedded in the GFRP rods and fibers bonded to steel reinforcing bars, respectively, whereas the strain deviation is +/-20 microepsilon for the two-point loading case. PMID:12206221

  10. Eulerian Formulation of Spatially Constrained Elastic Rods

    NASA Astrophysics Data System (ADS)

    Huynen, Alexandre

    by means of either its relative position with respect to the constraint axis (contact-free segments) or its angular position on the constraint surface (continuous contacts.) This formulation circumvents both drawbacks that afflict the conventional Lagrangian approach associated with the segmentation strategy. As the a priori unknown domain, viz. the rod length, is substituted for the known constraint axis, the free boundary problem and the associated isoperimetric constraints are converted into a classical two-point boundary value problem. Additionally, the description of the rod deflection by means of its eccentricity with respect to the constraint axis trivializes the assessment of the unilateral contact condition. Along continuous contacts, this formulation expresses the strain variables, measuring the rod change of shape, in terms of the geometric invariants of the constraint surface, and emphasizes the influence of the constraint local geometry on the reaction pressure. Formalizing the segmentation strategy, a computational model that exploits the Eulerian formulation of the rod governing equations is devised. To solve the quasi-static deflection of elastic rods constrained inside or around a tube-like surface, this computational model identifies the number of contacts, their nature (either discrete or continuous), and the rod configuration at the connections that satisfies the unilateral contact condition and preserves the rod integrity along the sequence of elementary problems.

  11. Control rod driveline and grapple

    DOEpatents

    Germer, John H.

    1987-01-01

    A control rod driveline and grapple is disclosed for placement between a control rod drive and a nuclear reactor control rod containing poison for parasitic neutron absorption required for reactor shutdown. The control rod is provided with an enlarged cylindrical handle which terminates in an upwardly extending rod to provide a grapple point for the driveline. The grapple mechanism includes a tension rod which receives the upwardly extending handle and is provided with a lower annular flange. A plurality of preferably six grapple segments surround and grip the control rod handle. Each grapple rod segment grips the flange on the tension rod at an interior upper annular indentation, bears against the enlarged cylindrical handle at an intermediate annulus and captures the upwardly flaring frustum shaped handle at a lower and complementary female segment. The tension rods and grapple segments are surrounded by and encased within a cylinder. The cylinder terminates immediately and outward extending annulus at the lower portion of the grapple segments. Excursion of the tension rod relative to the encasing cylinder causes rod release at the handle by permitting the grapple segments to pivot outwardly and about the annulus on the tension rod so as to open the lower defined frustum shaped annulus and drop the rod. Relative movement between the tension rod and cylinder can occur either due to electromagnetic release of the tension rod within defined limits of travel or differential thermal expansion as between the tension rod and cylinder as where the reactor exceeds design thermal limits.

  12. Passive hyporheic flux meter - measuring nitrate flux to the reactive sites in the river bed

    NASA Astrophysics Data System (ADS)

    Kunz, Julia Vanessa; Borchardt, Dietrich; Rode, Michael; Annable, Michael

    2015-04-01

    Most European lowland rivers are afflicted by high nitrate loads, modified morphology and discharge regulations, resulting in restricted capacity to retain nitrate. In those nutrient saturated rivers, sediment bound denitrification is the only process by which nitrate is removed from the system. Despite the importance of the hyporheic zone in nutrient reduction we are lacking detailed information on the transport to and retention at those reactive sites. Passive flux meters have successfully been used to measure contaminant transport to aquifers (eg Cho and Annable 2007). Here we present how a modification of those samplers can be used to quantify nitrate flux to and intermediate storage patterns in the interstices of an agriculturally impacted river. Installed in the river bed sediments, water flux and nutrient quantities passing through the device are recorded. While the amount of water flux serves as an index for connectivity of the hyporheic zone (exchange surface-subsurface water) the nitrate flux through the device can be seen as the portion of nitrate subjected to denitrification. The generated data on solute behavior in hyporheic zones are the missing puzzle to in-stream nitrate dynamics. Complementing flume and tracer experiments our approach depicts how discharge, morphology and sediment characteristics control the denitrification rate via the connectivity of the hyporheic zone. Passive hyporheic flux meter are a novel method to directly asses the quantity of removed nitrate by an in situ experiment.

  13. Micrometeorological measurements of ammonia and total reactive nitrogen exchange over semi-natural peatland

    NASA Astrophysics Data System (ADS)

    Brümmer, Christian; Richter, Undine; Schrader, Frederik; Kutsch, Werner

    2015-04-01

    Intensive agriculture generates a substantial atmospheric burden for nitrogen-limited ecosystems such as peatlands when the latter are located in close vicinity to arable sites and animal houses. The exchange of reactive nitrogen compounds between these bog ecosystems and the atmosphere is still not very well understood due to the lack of suitable measurement techniques. With recent advancements in laser spectrometry, we used a quantum cascade laser spectrometer as well as a custom-built total reactive atmospheric nitrogen (ΣNr) converter (TRANC) coupled to a fast-response chemiluminescence detector to measure NH3 and ΣNr concentrations, respectively. The analyzers' high temporal resolution allowed for determination of the respective nitrogen exchange within eddy covariance-based setups. Field campaigns were conducted at a northwestern German peatland site that is surrounded by an area of highly fertilized agricultural land and intensive livestock production (~1 km distance). The field site is part of a natural park with a very small remaining protected zone of less than 2 km x 2 km. Ammonia and ΣNr concentrations were highly variable between 2 to 110 ppb and 10 to 120 ppb, respectively. Peak values coincided with main fertilization periods on the neighboring agricultural land in early spring and fall. The trend in weekly averaged ΣNr concentrations from TRANC measurements was in good agreement with results from KAPS denuder filter systems when the latter were combined with the missing and apparently highly variable NOx contribution. Wind direction and land use in the closer vicinity clearly regulated whether ΣNr concentrations were NH3 or NOx-dominated. Ammonia uptake rates between 40 ng N m-2 s-1 and near-neutral exchange were observed. The cumulative net uptake for the period of investigation was ~700 g N ha-1 resulting in a dry net deposition of ~4 kg N ha-1 when extrapolated to an entire year, whereas KAPS denuder measurements in combination with dry

  14. Neutron economic reactivity control system for light water reactors

    DOEpatents

    Luce, Robert G.; McCoy, Daniel F.; Merriman, Floyd C.; Gregurech, Steve

    1989-01-01

    A neutron reactivity control system for a LWBR incorporating a stationary seed-blanket core arrangement. The core arrangement includes a plurality of contiguous hexagonal shaped regions. Each region has a central and a peripheral blanket area juxapositioned an annular seed area. The blanket areas contain thoria fuel rods while the annular seed area includes seed fuel rods and movable thoria shim control rods.

  15. Modeling reactive halogen species based on measurements at the Irish West Coast

    NASA Astrophysics Data System (ADS)

    Seitz, K.; von Glasow, R.; Platt, U.; Sommariva, R.; Pöhler, D.; Buxmann, J.

    2011-12-01

    We performed model studies based on measurements of reactive halogen species performed at Mace Head and Mweenish Bay at the Irish West Coast in summer 2007. The measurements were made using Differential Optical Absorption Spectroscopy (DOAS) and showed a strong heterogeneity of the spatial distribution of molecular iodine and iodine oxide. The model study was aimed at obtaining a better understanding of the spatial distribution of the trace gases, the mechanisms that lead to the formation of new particles and the impact of iodine emissions on atmospheric chemistry. We used the one-dimensional model MISTRA, which was initialized with the conditions encountered at the Irish West Coast. The iodine flux (from macro algae) was adjusted so that the model reproduces the observed IO mixing ratios. A number of different model runs were performed in order to quantify the impact of iodine chemistry on local and regional photochemistry under different meteorological conditions. The model suggests that inorganic iodine is rapidly mixed vertically: About 75% of the inorganic iodine is transported upwards, which is in good agreement with field measurements using multi-axis DOAS indicating a significant amount of IO in higher layers of the lower troposphere. Furthermore, the model was able to reproduce the field measurements of IO and molecular iodine during day and night. Not only the modeled mixing ratios, but also the spatial distribution of the iodine species was in good agreement with the field studies. The model also qualitatively reproduced the nucleation of aerosol particles that was observed during the field campaigns. The model results also suggest that IO2- in sulphate particles as well as in sea salt particles is oxidized to IO3- during the model runs. Most interestingly, the model showed strong indications for rapid multiphase cycling of halogen species as well as an exciting link between the chemistry of bromine and iodine: Iodine is taken up on the particles in the

  16. Modeling reactive halogen species based on measurements at the Irish West Coast

    NASA Astrophysics Data System (ADS)

    Seitz, Katja; Buxmann, Joelle; Pöhler, Denis; Sommariva, Roberto; Platt, Ulrich; von Glasow, Roland

    2010-05-01

    We performed model studies based on measurements of reactive halogen species at Mace Head and Mweenish Bay at the Irish West Coast. The measurements were made using Differential Optical Absorption Spectroscopy (DOAS) and showed a strong heterogeneity for the spatial distribution of molecular iodine and iodine oxide. The model study was performed in order to get a better understanding of the spatial distribution of the trace gases, the mechanisms that lead to the formation of new particles and the impact of iodine emissions on atmospheric chemistry. We used the one-dimensional model MISTRA to obtain a better understanding of the related processes. The model was initialized based on the conditions for the Irish West Coast, the iodine flux (from macro algae) was adjusted so that the model reproduces the observed IO mixing ratios. A number of different model runs were performed to be able to quantify the impacts of iodine chemistry on local and regional photochemistry under different meteorological conditions. The model suggests that inorganic iodine is rapidly mixed vertically: About 75% of the inorganic iodine is transported upwards, which is in good agreement with field measurements using multi-axis DOAS that indicate a significant amount of IO in higher layers of the lower troposphere. Furthermore the model was able to reproduce the field measurements of IO and molecular iodine during day and night. Not only the modeled mixing ratios, but also the spatial distribution of the iodine species was in good agreement with the field studies. The model also reproduced qualitatively the nucleation of aerosol particles that was observed during the field campaigns. The model results also suggest that IO2- in sulphate as well as in sea salt particles gets oxidized to IO3- during the model runs. Most interestingly, the model showed strong indications of for rapid multiphase cycling of halogen species and an exciting link between the chemistry of bromine and iodine: Iodine is

  17. Application of microchip assay system for the measurement of C-reactive protein in human saliva.

    PubMed

    Christodoulides, Nicolaos; Mohanty, Sanghamitra; Miller, Craig S; Langub, M Chris; Floriano, Pierre N; Dharshan, Priya; Ali, Mehnaaz F; Bernard, Bruce; Romanovicz, Dwight; Anslyn, Eric; Fox, Philip C; McDevitt, John T

    2005-03-01

    In the last decade, saliva has been advocated as a non-invasive alternative to blood as a diagnostic fluid. However, use of saliva has been hindered by the inadequate sensitivity of current methods to detect the lower salivary concentrations of many constituents compared to serum. Furthermore, developments in the areas related to lab-on-a-chip systems for saliva-based point of care diagnostics are complicated by the high viscosity and heterogeneous properties associated with this diagnostic fluid. The biomarker C-reactive protein (CRP) is an acute phase reactant and a well-accepted indicator of inflammation. Numerous clinical studies have established elevated serum CRP as a strong, independent risk factor for the development of cardiovascular disease (CVD). CVD has also been associated with oral infections (i.e. periodontal diseases) and there is evidence that systemic CRP may be a link between the two. Clinical measurements of CRP in serum are currently performed with "high sensitivity" CRP (hsCRP) enzyme-linked immunosorbent assay (ELISA) tests that lack the sensitivity for the detection of this important biomarker in saliva. Because measurement of salivary CRP may represent a novel approach for diagnosing and monitoring chronic inflammatory disease, including CVD and periodontal diseases, the objective of this study was to apply an ultra-sensitive microchip assay system for the measurement of CRP in human saliva. Here, we describe this novel lab-on-a-chip system in its first application for the measurement of CRP in saliva and demonstrate its advantages over the traditional ELISA method. The increased sensitivity of the microchip system (10 pg ml(-1) of CRP with 1000-fold dilution of saliva sample) is attributed to its inherent increased signal to noise ratio, resulting from the higher bead surface area available for antigen/antibody interactions and the high stringency washes associated with this approach. Finally, the microchip assay system was utilized in

  18. Measurement of the atmospheric reactivity of emissions from gasoline and alternative-fueled vehicles: Assessment of available methodologies. Part 1. Indoor smog chamber study of reactivity. Part 2. Assessment of airtrak as a reactivity analyzer. Final report for the second year, March 1, 1994-February 28, 1995

    SciTech Connect

    Kelly, N.A.; Wang, P.; Hurley, M.D.; Japar, S.M.; Chang, T.

    1996-06-13

    During the second year of the GM smog chamber study of incremental reactivity the authors performed smog chamber experiments to measure three important properties of incremental reactivity. First, they challenged the linear relationship between the Carter factors and the chamber-measured reactivities found during the first-year smog chamber study. Second, they compared the predicted and measured smog formation in simple and complex mixtures. Third, they measured the incremental reactivities of three hydrocarbons (n-butane, propene, and p-xylene) as well as the urban-surrogate mixture at three different temperatures, 22 deg C, 32 deg C (the default), and 42 deg C, to determine how temperature affects both the absolute and the relative reactivity. Finally, they conducted experiments in which the incremental reactivity of NO2 was measured in order to test the Integrated Empirical Rate (IER) model.

  19. Reactivity of chlorine radical with submicron palmitic acid particles: kinetic measurements and products identification

    NASA Astrophysics Data System (ADS)

    Mendez, M.; Ciuraru, R.; Gosselin, S.; Batut, S.; Visez, N.; Petitprez, D.

    2013-06-01

    The heterogeneous reaction of Cl. radicals with sub-micron palmitic acid (PA) particles was studied in an aerosol flow tube in the presence or in the absence of O2. Fine particles were generated by homogeneous condensation of PA vapors and introduced in the reactor where chlorine atoms are produced by photolysis of Cl2 using UV lamps surrounding the reactor. The effective reactive uptake coefficient (γ) has been determined from the rate loss of PA measured by GC/MS analysis of reacted particles as a function of the chlorine exposure. In the absence of O2, γ = 14 ± 5 indicates efficient secondary chemistry involving Cl2. GC/MS analyses have shown the formation of monochlorinated and polychlorinated compounds in the oxidized particles. Although, the PA particles are solid, the complete mass can be consumed. In the presence of oxygen, the reaction is still dominated by secondary chemistry but the propagation chain length is smaller than in the absence of O2 which leads to an uptake coefficient γ = 3 ± 1. In the particulate phase, oxocarboxylic acids and dicarboxylic acids are identified by GC/MS. Formation of alcohols and monocarboxylic acids are also suspected. All these results show that solid organic particles could be efficiently oxidized by gas-phase radicals not only on their surface, but also in bulk by mechanisms which are still unclear. Furthermore the identified reaction products are explained by a chemical mechanism showing the pathway of the formation of more functionalized products. They help to understand the aging of primary tropospheric aerosol containing fatty acids.

  20. Reactivity of chlorine radical with submicron palmitic acid particles: kinetic measurements and product identification

    NASA Astrophysics Data System (ADS)

    Mendez, M.; Ciuraru, R.; Gosselin, S.; Batut, S.; Visez, N.; Petitprez, D.

    2013-12-01

    The heterogeneous reaction of Cl• radicals with submicron palmitic acid (PA) particles was studied in an aerosol flow tube in the presence or in the absence of O2. Fine particles were generated by homogeneous condensation of PA vapours and introduced into the reactor, where chlorine atoms were produced by photolysis of Cl2 using UV lamps surrounding the reactor. The effective reactive uptake coefficient (γ) has been determined from the rate loss of PA measured by gas chromatography-mass spectrometer (GC/MS) analysis of reacted particles as a function of the chlorine exposure. In the absence of O2, γ = 14 ± 5 indicates efficient secondary chemistry involving Cl2. GC/MS analysis has shown the formation of monochlorinated and polychlorinated compounds in the oxidized particles. Although the PA particles are solid, the complete mass can be consumed. In the presence of oxygen, the reaction is still dominated by secondary chemistry but the propagation chain length is smaller than in the absence of O2, which leads to an uptake coefficient γ = 3 ± 1. In the particulate phase, oxocarboxylic acids and dicarboxylic acids were identified by GC/MS. The formation of alcohols and monocarboxylic acids is also suspected. A reaction pathway for the main products and more functionalized species is proposed. All these results show that solid organic particles could be efficiently oxidized by gas-phase radicals not only on their surface but also in bulk by mechanisms which are still unclear. They help to understand the aging of primary tropospheric aerosol containing fatty acids.

  1. Experimental design for reflection measurements of highly reactive liquid or solid substances with application to liquid sodium

    SciTech Connect

    Chan, S.H.; Gossler, A.A.

    1980-06-30

    A versatile goniometer system with associated electronic components and mechanical instruments has been assembled. It is designed to measure spectral, specular reflectances of highly reactive liquid or solid substances over a spectral range of 0.3 to 9 ..mu.. and incidence angles of 12 to 30/sup 0/ off the normal direction. The capability of measuring reflectances of liquid substances clearly distinguishes this experimental design from conventional systems which are applicable only to solid substances. This design has been used to measure the spectral, specular reflectance of liquid sodium and preliminary results obtained are compared with those of solid sodium measured by other investigators.

  2. Proactive, Reactive, and Romantic Relational Aggression in Adulthood: Measurement, Predictive Validity, Gender Differences, and Association with Intermittent Explosive Disorder

    PubMed Central

    Murray-Close, Dianna; Ostrov, Jamie M.; Nelson, David A.; Crick, Nicki R.; Coccaro, Emil F.

    2009-01-01

    The psychometric properties of a recently introduced adult self-report of relational aggression are presented. Specifically, the predictive utility of proactive and reactive peer-directed relational aggression, as well as romantic relational aggression, are explored in a large (N = 1387) study of adults. The measure had adequate reliability and validity and the subscales demonstrated unique predictive abilities for a number of dependent variables. In particular, reactive but not proactive relational aggression was uniquely associated with history of abuse, hostile attribution biases, and feelings of distress regarding relational provocation situations. Reactive relational aggression was also more strongly related to anger and hostility than proactive aggression. In addition, relational aggression in the context of romantic relationships was uniquely related to anger, hostility, impulsivity, history of abuse, hostile attribution biases, and emotional sensitivity to relational provocations, even when controlling for peer-directed relational aggression. Gender differences in overall levels of relational aggression were not observed; however, males were most likely to engage in peer-directed proactive and reactive relational aggression whereas females were most likely to engage in romantic relational aggression. In a second study (N = 150), relational aggression was higher in a sample of adults with Intermittent Explosive Disorder than in a sample of healthy controls or psychiatric controls. The findings highlight the importance of assessing subtypes of relational aggression in adult samples. Ways in which this measure may extend research in psychology and psychiatry are discussed. PMID:19822329

  3. Rebirth of a control rod at the Phenix power plant

    SciTech Connect

    De Carvalho, Corinne; Vignau, Bernard; Masson, Marc

    2007-07-01

    under a metre of sodium. 4 poles will have been required for this operation: - a pole for draining the rod and uncovering the bearing surface, - a borescope pole, - a pole for cleaning the bearing surface, - a pole for inspecting the bearing surface. The operation resulted in a very satisfactory bearing capacity of approx. 80 daN. This paper also examines the history of contamination of the control rod and the rod mechanism. It outlines the hypotheses for the source of this contamination and the measures taken to counteract this problem. (authors)

  4. Reactivity control assembly for nuclear reactor

    DOEpatents

    Bollinger, Lawrence R.

    1984-01-01

    Reactivity control assembly for nuclear reactor comprises supports stacked above reactor core for holding control rods. Couplers associated with the supports and a vertically movable drive shaft have lugs at their lower ends for engagement with the supports.

  5. Understanding flame rods

    SciTech Connect

    McAuley, J.A. Jr.

    1995-11-01

    The flame rod is probably the least understood method of flame detection. Although it is not recommended for oilfired equipment, it is very common on atmospheric, or {open_quotes}in-shot,{close_quotes} gas burners. It is also possible, although not common, to have an application with a constant gas pilot, monitored by a flame rod, and maintaining an oil main flame. Regardless of the application, chances are that flame rods will be encountered during the course of servicing. The technician today must be versatile and able to work on many different types of equipment. One must understand the basic principles of flame rods, and how to correct potential problems. The purpose of a flame detection system is two-fold: (1) to prove there is no flame when there shouldn`t be one, and (2) to prove there is a flame when there should be one. Flame failure response time is very important. This is the amount of time it takes to realize there is a loss of flame, two to four seconds is typical today. Prior to flame rods, either bi-metal or thermocouple type flame detectors were common. The response time for these detectors was up to three minutes, seldom less than one minute.

  6. Intramedullary rodding in osteogenesis imperfecta.

    PubMed

    Mulpuri, K; Joseph, B

    2000-01-01

    The results of intramedullary rodding of long bones of 16 children with osteogenesis imperfecta, over a 10-year period, were analyzed. Sheffield elongating rods or non-elongating rods were used. The frequency of fractures was dramatically reduced after implantation of either type of rod, and the ambulatory status improved in all instances. The results were significantly better after Sheffield rodding with regard to the frequency of complications requiring reoperations and the longevity of the rods. Migration of the rods, encountered frequently, appears to be related to improper placement of the rods in the bone. It seems likely that if care is taken to ensure precise placement of a rod of appropriate size, several of these complications may be avoided. PMID:10739296

  7. Measuring Physical Activity with Pedometers in Older Adults with Intellectual Disability: Reactivity and Number of Days

    ERIC Educational Resources Information Center

    Hilgenkamp, Thessa; Van Wijck, Ruud; Evenhuis, Heleen

    2012-01-01

    The minimum number of days of pedometer monitoring needed to estimate valid average weekly step counts and reactivity was investigated for older adults with intellectual disability. Participants (N = 268) with borderline to severe intellectual disability ages 50 years and older were instructed to wear a pedometer for 14 days. The outcome measure…

  8. QUALITATIVE MEASUREMENTS OF IGE AND IGG IN HUMAN ASTHMATIC SERUM FOR MOLD REACTIVITY

    EPA Science Inventory

    Rational: Molds have the ability to induce allergic asthma-like responses in mouse models; however, their role in human disease is unclear. This study was to develop a screening tool for reactivity of human sera to mold extracts by using a minimal amount of sera for a qual...

  9. Measurement of affective state during chronic nicotine treatment and withdrawal by affective taste reactivity in mice: the role of endocannabinoids.

    PubMed

    Wing, Victoria C; Cagniard, Barbara; Murphy, Niall P; Shoaib, Mohammed

    2009-10-01

    Despite tobacco being highly addictive, it is unclear if nicotine has significant affective properties. To address this, we studied taste reactions to gustatory stimuli, palatable sucrose and unpalatable quinine, which are believed to reflect ongoing affective state. Taste reactivity was assessed during chronic nicotine administration and spontaneous withdrawal and the role of the endogenous cannabinoids was also investigated. C57BL6J mice were implanted with intraoral fistula to allow passive administration of solutions. In the first study, taste reactivity was tracked throughout chronic vehicle or nicotine (12 mg/kg/day) infusion via osmotic minipumps and spontaneous withdrawal following removal of minipumps. In the second study, the endocannabinoid CB1-receptor antagonist AM251 (1, 3 and 10mg/kg, intraperitoneal) or vehicle was acutely administered before taste reactivity measurement during chronic nicotine administration. Chronic nicotine treatment and spontaneous withdrawal did not influence taste reactions to sucrose or quinine. AM251 decreased positive reactions to sucrose and increased negative reactions to quinine. The effects of AM251 were respectively attenuated and enhanced in nicotine infused mice. These results suggest chronic nicotine exposure and withdrawal has no apparent affective sequelae, as probed by taste reactivity, and thus may not explain the difficulty tobacco-users have in achieving abstinence. In contrast, endocannabinoids elevate affective state in drug-naïve animals and changes in endogenous endocannabinoid tone may underlie compensations in affective state during chronic nicotine exposure. PMID:19540830

  10. The effect of relative humidity on the detection of pyrrole by PTR-MS for OH reactivity measurements

    NASA Astrophysics Data System (ADS)

    Sinha, V.; Custer, T. G.; Kluepfel, T.; Williams, J.

    2009-04-01

    The hydroxyl radical (OH) is the most important atmospheric oxidant. Recently Sinha et al. [1] developed a new method to measure the total OH reactivity of ambient air (OH sink) employing a proton transfer reaction mass spectrometer (PTR-MS) as a detector. The new method uses pyrrole (C4H4NH) as a reagent and for an OH reactivity measurement this species must be measured under both dry (~ 0% RH) and humid air ( > 30% RH). Here, we investigate the sensitivity dependence of the PTR-MS for pyrrole, as a function of relative humidity in the sampled air. Various normalizations with respect to the H3O+ ion and its different hydrated clusters ions H3O+(H2O)n=1,2,3 are compared. It is shown that both the primary ion signal (H3O+ ion m/z = 19) and the first water cluster ion H3O+(H2O) (m/z = 37) should be used for pyrrole quantification. However, in spite of using this normalization, the PTR-MS sensitivity for pyrrole changes by as much as 16 % between dry (~ 0% RH) and humid air (above 30 % RH), with higher sensitivity when the sampled air is humid. Thus, for accurate quantification of pyrrole using a PTR-MS, calibration factors appropriate to dry and humid air should be employed. We recommend that humidity dependence of the PTR-MS be taken into account when reactivity measurements are performed using the pyrrole based comparative reactivity method (CRM). [1]. V. Sinha, J. Williams, J.N. Crowley, and J. Lelieveld, Atmos. Chem. Phys. 8 (2008) 2213-2227

  11. The effect of relative humidity on the detection of pyrrole by PTR-MS for OH reactivity measurements

    NASA Astrophysics Data System (ADS)

    Sinha, V.; Custer, T. G.; Kluepfel, T.; Williams, J.

    2009-05-01

    The hydroxyl radical (OH) is the most important atmospheric oxidant. Recently Sinha et al. [V. Sinha, J. Williams, J.N. Crowley, J. Lelieveld, Atmos. Chem. Phys. 8 (2008) 2213] developed a new method to measure the total OH reactivity of ambient air (OH sink) employing a proton transfer reaction mass spectrometer (PTR-MS) as a detector. The new method uses pyrrole (C4H4NH) as a reagent and for an OH reactivity measurement this species must be measured under both dry (~0% RH) and humid air (>30% RH). Here, we investigate the sensitivity dependence of the PTR-MS for pyrrole, as a function of relative humidity in the sampled air. Various normalizations with respect to the H3O+ ion and its different hydrated cluster ions H3O+(H2O)n=1,2,3 are compared. It is shown that both the primary ion signal (H3O+ ion m/z = 19) and the first water cluster ion H3O+(H2O) (m/z = 37) should be used for pyrrole quantification. However, in spite of using this normalization, the PTR-MS sensitivity for pyrrole changes by as much as 16% between dry (~0% RH) and humid air (above 30% RH), with higher sensitivity when the sampled air is humid. Thus, for accurate quantification of pyrrole using a PTR-MS, calibration factors appropriate to dry and humid air should be employed. We recommend that humidity dependence of the PTR-MS be taken into account when reactivity measurements are performed using the pyrrole based comparative reactivity method (CRM).

  12. COMPOSITE CONTROL ROD

    DOEpatents

    Rock, H.R.

    1963-12-24

    A composite control rod for use in controlling a nuclear reactor is described. The control rod is of sandwich construction in which finned dowel pins are utilized to hold together sheets of the neutron absorbing material and nonabsorbing structural material thereby eliminating the need for being dependent on the absorbing material for structural support. The dowel pins perform the function of absorbing the forces due to differential thermal expansion, seating further with the fins into the sheets of material and crushing before damage is done either to the absorbing or non-absorbing material. (AEC)

  13. Closed form expressions for crack mouth displacements and stress intensity factors for chevron notched short bar and short rod specimens based on experimental compliance measurements

    NASA Technical Reports Server (NTRS)

    Bubsey, R. T.; Orange, T. W.; Pierce, W. S.; Shannon, J. L., Jr.

    1992-01-01

    A set of equations are presented describing certain fracture mechanics parameters for chevron notch bar and rod specimens. They are developed by fitting compliance calibration data reported earlier. The equations present the various parameters in their most useful forms. The data encompass the entire range of the specimen geometries most commonly used. Their use will facilitate the testing and analysis of brittle metals, ceramics, and glasses.

  14. Total OH reactivity measurements in ambient air in a southern Rocky Mountain ponderosa pine forest during BEACHON-SRM08 summer campaign

    SciTech Connect

    Nakashima, Yoshihiro; Kato, Shungo; Greenberg, Jim; Harley, P.; Karl, Thomas G.; Turnipseed, A.; Apel, Eric; Guenther, Alex B.; Smith, Jim; Kajii, Yoshizumi

    2014-03-01

    Total OH reactivity was measured during the Bio-hydro-atmosphere interactions of Energy, Aerosols, Carbon, H2O, Organics and Nitrogen-Southern Rocky Mountain 2008 field campaign (BEACHON-SRM08) held at Manitou Experimental Forest (MEF) in Colorado USA during the summer season in August, 2008. The averaged total OH reactivity was 6.8 s-1, smaller than that measured in urban or suburban areas, while sporadically high OH reactivity was also observed during some evenings. The total OH reactivity measurements were accompanied by observations of traces species such as CO, NO, NOy, O3 and SO2 and VOCs. From the calculation of OH reactivity based on the analysis of these trace species, 35.3-46.3% of OH reactivity for VOCs came from biogenic species that are dominated by 2-methyl-3-butene-2-ol (MBO), and monoterpenes. MBO was the most prominent contribution to OH reactivity of any other trace species. A comparison of observed and calculated OH reactivity shows that the calculated OH reactivity is 29.5-34.8% less than the observed value, implying the existence of missing OH sink. One of the candidates of missing OH was thought to be the oxidation products of biogenic species.

  15. Radiological characterization of spent control rod assemblies

    SciTech Connect

    Lepel, E.A.; Robertson, D.E.; Thomas, C.W.; Pratt, S.L.; Haggard, D.L.

    1995-10-01

    This document represents the final report of an ongoing study to provide radiological characterizations, classifications, and assessments in support of the decommissioning of nuclear power stations. This report describes the results of non-destructive and laboratory radionuclide measurements, as well as waste classification assessments, of BWR and PWR spent control rod assemblies. The radionuclide inventories of these spent control rods were determined by three separate methodologies, including (1) direct assay techniques, (2) calculational techniques, and (3) by sampling and laboratory radiochemical analyses. For the BWR control rod blade (CRB) and PWR burnable poison rod assembly (BPRA), {sup 60}Co and {sup 63}Ni, present in the stainless steel cladding, were the most abundant neutron activation products. The most abundant radionuclide in the PWR rod cluster control assembly (RCCA) was {sup 108m}Ag (130 yr halflife) produced in the Ag-In-Cd alloy used as the neutron poison. This radionuclide will be the dominant contributor to the gamma dose rate for many hundreds of years. The results of the direct assay methods agree very well ({+-}10%) with the sampling/radiochemical measurements. The results of the calculational methods agreed fairly well with the empirical measurements for the BPRA, but often varied by a factor of 5 to 10 for the CRB and the RCCA assemblies. If concentration averaging and encapsulation, as allowed by 10CFR61.55, is performed, then each of the entire control assemblies would be classified as Class C low-level radioactive waste.

  16. Branch-level measurement of total OH reactivity for constraining unknown BVOC emission during the CABINEX (Community Atmosphere-Biosphere INteractions Experiments)-09 Field Campaign

    NASA Astrophysics Data System (ADS)

    Kim, S.; Guenther, A.; Karl, T.; Greenberg, J.

    2011-03-01

    We present OH reactivity measurements using the comparative reactivity method with a branch enclosure technique for four different tree species (red oak, white pine, beech and red maple) in the UMBS PROPHET tower footprint during the Community Atmosphere Biosphere INteraction EXperiment (CABINEX) field campaign in July of 2009. Proton Transfer Reaction-Mass Spectrometry (PTR-MS) was sequentially used as a detector for OH reactivity and BVOC including isoprene and monoterpenes (MT), in enclosure air, so that the measurement dataset contains both measured OH reactivity and calculated OH reactivity from well-known BVOC. The results indicate that isoprene and MT, and in one case a sesquiterpene, can account for the measured OH reactivity. Significant discrepancy between measured OH reactivity and calculated OH reactivity from isoprene and MT is found for the red maple enclosure dataset but it can be reconciled by adding reactivity from emission of a sesquiterpene, α-farnesene, detected by GC-MS. This leads us to conclude that no significant unknown BVOC emission contributed to ambient OH reactivity from these trees at least during the study period. This conclusion leads us to explore the contribution from unmeasured isoprene (the dominant OH sink in this ecosystem) oxidation products such as hydroxyacetone, glyoxal, methylglyoxal and C4 and C5-hydroxycarbonyl using recently published isoprene oxidation mechanisms (Mainz Isoprene Mechanism II and Leuven Isoprene Mechanism). Evaluation of conventionally unmeasured first generation oxidation products of isoprene and their possible contribution to ambient missing OH reactivity indicates that the ratio of OH reactivity from unmeasured products over OH reactivity from MVK + MACR is strongly dependent on NO concentrations. The unmeasured oxidation products can contribute ~7.2% (8.8% from LIM and 5.6% by MIM 2 when NO = 100 pptv) of the isoprene contribution towards total ambient OH reactivity. This amount can explain ~8

  17. RCRA corrective measures using a permeable reactive iron wall US Coast Guard Support Center, Elizabeth City, North Carolina

    SciTech Connect

    Schmithors, W.L.; Vardy, J.A.

    1997-12-31

    A chromic acid release was discovered at a former electroplating shop at the U.S. Coast Guard Support Center in Elizabeth City, North Carolina. Initial investigative activities indicated that chromic acid had migrated into the subsurface soils and groundwater. In addition, trichloroethylene (TCE) was also discovered in groundwater during subsequent investigations of the hexavalent chromium (Cr VI) plume. Corrective measures were required under the Resource Conservation and Recovery Act (RCRA). The in-situ remediation method, proposed under RCRA Interim Measures to passively treat the groundwater contaminants, uses reactive zero-valent iron to reductively dechlorinate the chlorinated compounds and to mineralize the hexavalent chromium. A 47 meter by 0.6 meter subsurface permeable iron wall was installed downgradient of the source area to a depth of 7 meters using a direct trenching machine. The iron filings were placed in the ground as the soils were excavated from the subsurface. This is the first time that direct trenching was used to install reactive zero-valent iron filings. Over 250 metric tons of iron filings were used as the reactive material in the barrier wall. Installation of the iron filings took one full day. Extensive negotiations with regulatory agencies were required to use this technology under the current facility Hazardous Waste Management Permit. All waste soils generated during the excavation activities were contained and treated on site. Once contaminant concentrations were reduced the waste soils were used as fill material.

  18. Measurements of friction coefficients and cohesion for faulting and fault reactivation in laboratory models using sand and sand mixtures

    NASA Astrophysics Data System (ADS)

    Krantz, Robert W.

    1991-03-01

    Simple laboratory tests have been made on dry quartz sand and on mixtures of sand and clay and sand and cement. Tests were made on both low- and high-density specimens of each mixture, as determined by physical handling techniques. The tests included measurements of density, estimates of the coefficient of internal friction based on fault orientation, and estimates of the friction coefficients and cohesion values for fault initiation and reactivation in a shear frame apparatus, which was also used to test artificial fault zones made from pure clay, glass microspheres, and wheat flour. The results suggest that density is determined more by handling technique than by composition, and that friction coefficients and perhaps cohesion both increase with increasing density. The shear testing revealed a consistent drop in cohesion for fault reactivation in all densely packed mixtures tested. Although small, this drop may be significant for some types of laboratory models.

  19. Advancing Reactive Tracer Methods for Measurement of Thermal Evolution in Geothermal Reservoirs: Final Report

    SciTech Connect

    Mitchell A. Plummer; Carl D. Palmer; Earl D. Mattson; Laurence C. Hull; George D. Redden

    2011-07-01

    The injection of cold fluids into engineered geothermal system (EGS) and conventional geothermal reservoirs may be done to help extract heat from the subsurface or to maintain pressures within the reservoir (e.g., Rose et al., 2001). As these injected fluids move along fractures, they acquire heat from the rock matrix and remove it from the reservoir as they are extracted to the surface. A consequence of such injection is the migration of a cold-fluid front through the reservoir (Figure 1) that could eventually reach the production well and result in the lowering of the temperature of the produced fluids (thermal breakthrough). Efficient operation of an EGS as well as conventional geothermal systems involving cold-fluid injection requires accurate and timely information about thermal depletion of the reservoir in response to operation. In particular, accurate predictions of the time to thermal breakthrough and subsequent rate of thermal drawdown are necessary for reservoir management, design of fracture stimulation and well drilling programs, and forecasting of economic return. A potential method for estimating migration of a cold front between an injection well and a production well is through application of reactive tracer tests, using chemical whose rate of degradation is dependent on the reservoir temperature between the two wells (e.g., Robinson 1985). With repeated tests, the rate of migration of the thermal front can be determined, and the time to thermal breakthrough calculated. While the basic theory behind the concept of thermal tracers has been understood for some time, effective application of the method has yet to be demonstrated. This report describes results of a study that used several methods to investigate application of reactive tracers to monitoring the thermal evolution of a geothermal reservoir. These methods included (1) mathematical investigation of the sensitivity of known and hypothetical reactive tracers, (2) laboratory testing of novel

  20. Anchor for Fiberglas Guy Rod

    NASA Technical Reports Server (NTRS)

    Wilson, A. H.

    1982-01-01

    Solution to problem of anchoring fiberglas guy rods to install nut with threads on outer circumference, followed by aluminum sleeve. Sleeve has opening oval at upper and round at bottom end. End of rod is split so fiberglas wedge can be inserted to form V-shaped end. Spread end of rod fits into tapered hole in sleeve and threaded aluminum coupling is put over rod and sleeve.

  1. SU-D-204-05: Quantitative Comparison of a High Resolution Micro-Angiographic Fluoroscopic (MAF) Detector with a Standard Flat Panel Detector (FPD) Using the New Metric of Generalized Measured Relative Object Detectability (GM-ROD)

    SciTech Connect

    Russ, M; Ionita, C; Bednarek, D; Rudin, S

    2015-06-15

    Purpose: In endovascular image-guided neuro-interventions, visualization of fine detail is paramount. For example, the ability of the interventionist to visualize the stent struts depends heavily on the x-ray imaging detector performance. Methods: A study to examine the relative performance of the high resolution MAF-CMOS (pixel size 75µm, Nyquist frequency 6.6 cycles/mm) and a standard Flat Panel Detector (pixel size 194µm, Nyquist frequency 2.5 cycles/mm) detectors in imaging a neuro stent was done using the Generalized Measured Relative Object Detectability (GM-ROD) metric. Low quantum noise images of a deployed stent were obtained by averaging 95 frames obtained by both detectors without changing other exposure or geometric parameters. The square of the Fourier transform of each image is taken and divided by the generalized normalized noise power spectrum to give an effective measured task-specific signal-to-noise ratio. This expression is then integrated from 0 to each of the detector’s Nyquist frequencies, and the GM-ROD value is determined by taking a ratio of the integrals for the MAF-CMOS to that of the FPD. The lower bound of integration can be varied to emphasize high frequencies in the detector comparisons. Results: The MAF-CMOS detector exhibits vastly superior performance over the FPD when integrating over all frequencies, yielding a GM-ROD value of 63.1. The lower bound of integration was stepped up in increments of 0.5 cycles/mm for higher frequency comparisons. As the lower bound increased, the GM-ROD value was augmented, reflecting the superior performance of the MAF-CMOS in the high frequency regime. Conclusion: GM-ROD is a versatile metric that can provide quantitative detector and task dependent comparisons that can be used as a basis for detector selection. Supported by NIH Grant: 2R01EB002873 and an equipment grant from Toshiba Medical Systems Corporation.

  2. OH Reactivity and Potential SOA Yields from Volatile Organic Compounds and Other Trace Gases Measured in Controlled Laboratory Biomass Burns

    NASA Astrophysics Data System (ADS)

    Gilman, J. B.; Warneke, C.; Kuster, W. C.; Goldan, P. D.; Veres, P. R.; Roberts, J. M.; de Gouw, J. A.; Burling, I. R.; Yokelson, R. J.

    2010-12-01

    A comprehensive suite of instruments were used to characterize volatile organic compounds (VOCs) and other trace gases (e.g., CO, CH4, NO2, etc.) emitted from controlled burns of various fuel types common to the Southeastern and Southwestern United States. These laboratory-based measurements were conducted in February 2009 at the U.S. Department of Agriculture’s Fire Sciences Laboratory in Missoula, Montana. An on-line GC-MS provided highly speciated VOC measurements of alkenes, alkanes, oxygenates, aromatics, biogenics, and nitrogen-containing compounds during the flaming or smoldering phases of replicate burns. The speciated GC-MS “grab” samples were integrated with fast-response gas-phase measurements (e.g., PTR-MS, PTR-IT-MS, NI-PT-CIMS, and FTIR) in order to determine VOC emission ratios and the fraction of identified vs. unidentifiable mass detected by PTR-MS. Emission ratios were used to calculate OH reactivity, which is a measure of potential ozone formation, as well as potential secondary organic aerosol (SOA) yields from the various fuel types. Small oxygenated VOCs had the highest emission ratios of the compounds observed. Alkenes dominated the VOC OH reactivity, which occasionally exceeded 1000 s-1. Calculated SOA yields from known precursors were dominated by aromatic VOCs, such as toluene, naphthalene (C10H8), and 1,3-benzenediol (C6H6O2, resorcinol). The contribution of several compounds not typically reported in ambient air measurements, such as substituted furans (C4H4O), pyrroles (C4H5N), and unsaturated C9 aromatics (C9H10), on OH reactivity and SOA yields will be discussed.

  3. Dynamic, multiaxial impact response of confined and unconfined ceramic rods

    SciTech Connect

    Wise, J.L.; Grady, D.E.

    1993-09-01

    A new configuration for impact testing was implemented which yielded time-resolved measurements of the dynamic response of materials undergoing multiaxial strain. With this`-Method, one end of an initially stationary rod (ie., right circular cylinder) of test material was subjected to planar impact with a flat-faced projectile. The test rod was either free (unconfined) or mounted within a close-fitting sleeve which provided lateral confinement. Velocity interferometer diagnostics monitored the axial (longitudinal) velocity of the rod free end, and the transverse (radial) velocity for one or more points on the periphery of the rod or confinement sleeve. Analysis of the resultant velocity records allowed assessment of material properties, such as wave speeds and compressive yield strength, without the requirement of intact recovery of the rod. Data were obtained for alumina (Coors AD-99.5) rods in a series of tests involving variations in confinement and peak impact stress.

  4. Single Rod Vibration in Axial Flow

    NASA Astrophysics Data System (ADS)

    Weichselbaum, Noah; Wang, Shengfu; Bardet, Philippe

    2013-11-01

    Fluid structure interaction of a single rod in axial flow is a coupled dynamical system present in many application including nuclear reactors, steam generators, and towed antenna arrays. Fluid-structure response can be quantified thanks to detailed experimental data where both structure and fluid responses are recorded. Such datum deepen understanding of the physics inherent to the system and provide high-dimensionality quantitative measurements to validate coupled structural and CFD codes with various level of complexity. In this work, single rods fixed on both ends in a concentric pipe, are subjected to an axial flow with Reynolds number based on hydraulic diameter of Re =4000. Rods of varying material stiffness and diameter are utilized in the experiment resulting in a range of dimensionless U between 0.5 and 1, where U = (ρA/EI)1/2uL. Experimental measurements of the velocity field around the rod are taken with PIV from time-resolved Nd:YLF laser and a high speed CMOS camera. Three-dimensional and temporal vibration and deflection of the rod is recorded with shadowgraphy utilizing two sets of pulsed high power LED and dedicated CMOS camera. Through integration of these two diagnostics, it is possible to reconstruct the full FSI domain providing unique validation data.

  5. REACTOR CONTROL ROD OPERATING SYSTEM

    DOEpatents

    Miller, G.

    1961-12-12

    A nuclear reactor control rod mechanism is designed which mechanically moves the control rods into and out of the core under normal conditions but rapidly forces the control rods into the core by catapultic action in the event of an emergency. (AEC)

  6. Reliable measures of behaviorally-evoked cardiovascular reactivity from a PC-based test battery: results from student and community samples.

    PubMed

    Kamarck, T W; Jennings, J R; Debski, T T; Glickman-Weiss, E; Johnson, P S; Eddy, M J; Manuck, S B

    1992-01-01

    This paper describes efforts to reduce measurement error in the assessment of cardiovascular reactivity by standardizing task requirements and by aggregating data across tasks and testing sessions. Using these methods, reliable measures of reactivity (.80 or greater) were obtained on five different measures of cardiovascular function (heart rate, systolic blood pressure, diastolic blood pressure, stroke volume, pre-ejection period) in samples of college students and community volunteers. Methodological limitations may have hampered previous efforts in this area. Current findings are consistent with a dispositional model of cardiovascular reactivity, and they suggest productive future strategies for obtaining reliable assessments. PMID:1609024

  7. Biomechanical study comparing a new combined rod-plate system with conventional dual-rod and plate systems.

    PubMed

    Sha, Mo; Ding, Zheng-Qi; Ting, Hu S; Kang, Liang-Qi; Zhai, Wen-Liang; Liu, Hui

    2013-02-01

    Most anterior spinal instrumentation systems are designed as either a plate or dual-rod system and have corresponding limitations. Dual-rod designs may offer greater adjustability; however, this system also maintains a high profile and lacks a locking design. Plate systems are designed to be stiffer, but the fixed configuration is not adaptable to the variety of vertebral body shapes. The authors designed a new combined rod-plate system (D-rod) to overcome these limitations and compared its biomechanical performance with the conventional dual-rod and plate system. Eighteen pig spinal specimens were divided into 3 groups (6 per group). An L1 corpectomy was performed and fixed with the D-rod (group A; n=6), Z-plate (Sofamor Danek, Memphis, Tennessee) (group B; n=6), or Ventrofix (Synthes, Paoli, Pennsylvania) (group C; n=6) system. T13-L2 range of motion was measured with a 6 degrees of freedom (ie, flexion-extension, lateral bending, and axial rotation) spine simulator under pure moments of 6.0 Nm. The D-rod and Ventrofix specimens were significantly stiffer than the Z-plate specimens (P<.05) based on results obtained from lateral bending and flexion-extension tests. The D-rod and Z-plate specimens were significantly stiffer than the Ventrofix specimens (P<.05) in axial rotation. The D-rod combines the advantages of the plate and dual-rod systems, where the anterior rod exhibits the design of a low-profile locking plate, enhanced stability, and decreased interference of the surrounding vasculature. The posterior rods function in compression and distraction, and the dual-rod system offers greater adjustability and control over screw placement. The results indicate that it may provide adequate stability for anterior thoracolumbar reconstruction. PMID:23383624

  8. Interest of the non linear fitting method for reactivity assessment using flux transient experiments

    SciTech Connect

    Geslot, B.; Jammes, C.

    2006-07-01

    Flux transient measurements, meaning rod drop or source jerk experiments, are useful to estimate subcritical core reactivity or control rod worth. Among numerous analysis methods, the most widely used is the so called 'inverse kinetics' method (IK). Based on the inversion of the counting rates, this method gives very good results when counting rates are high. When assessing far subcritical levels with low counting rates, it appears that results are biased and very imprecise. In order to overcome those problems in the case of measurements performed in the framework of the first phase of the RACE-T program, we used a non linear fitting method (NF) to analyse transient experiments. In this paper, we present the NF method reactivity estimator and study its behaviour, in terms of bias and uncertainties, on simulated transients. Then, RACE-T results on experimental source jerk measurements, obtained using IK and NF, are compared and discussed. (authors)

  9. Hafnium stainless steel absorber rod for control rod

    SciTech Connect

    Charnley, J.E.; Cearley, J.E.; Dixon, R.C.; Izzo, K.R.; Aiello, L.L.

    1989-08-01

    This patent describes an improvement in a control rod having a stainless steel body for enclosing a neutron absorbing poison, the control rod having movement along an axial direction for insertion into and out of a nuclear reactor for controlling a nuclear reaction. The improvement comprising: a piece of hafnium; a piece of stainless steel joined to the hafnium by a thin diffusion interface created by friction welding. The hafnium and the stainless steel oriented serially in the axial direction with the thin diffusion interface disposed normal to the axial direction of the control rod movement; means for confining the hafnium to movement along the axial direction with the control rod; and means for attaching the piece of stainless steel to the remaining portion of the control rod to load the weld therebetween under compression or tension during the control rod movement. Whereby the thin diffusion interface is loaded in tension or compression only upon dynamic movement of the control rod.

  10. Nitrosylated Hemoglobin Levels in Human Venous Erythrocytes Correlate with Vascular Endothelial Function Measured by Digital Reactive Hyperemia

    PubMed Central

    Lobysheva, Irina I.; Biller, Pauline; Gallez, Bernard; Beauloye, Christophe; Balligand, Jean-Luc

    2013-01-01

    Impaired nitric oxide (NO)–dependent endothelial function is associated with the development of cardiovascular diseases. We hypothesized that erythrocyte levels of nitrosylated hemoglobin (HbNO-heme) may reflect vascular endothelial function in vivo. We developed a modified subtraction method using Electron Paramagnetic Resonance (EPR) spectroscopy to identify the 5-coordinate α-HbNO (HbNO) concentration in human erythrocytes and examined its correlation with endothelial function assessed by peripheral arterial tonometry (PAT). Changes in digital pulse amplitude were measured by PAT during reactive hyperemia following brachial arterial occlusion in a group of healthy volunteers (50 subjects). Erythrocyte HbNO levels were measured at baseline and at the peak of hyperemia. We digitally subtracted an individual model EPR signal of erythrocyte free radicals from the whole EPR spectrum to unmask and quantitate the HbNO EPR signals. Results Mean erythrocyte HbNO concentration at baseline was 219+/−12 nmol/L (n = 50). HbNO levels and reactive hyperemia (RH) indexes were higher in female (free of contraceptive pills) than male subjects. We observed a dynamic increase of HbNO levels in erythrocytes isolated at 1–2 min of post-occlusion hyperemia (120+/−8% of basal levels); post-occlusion HbNO levels were correlated with basal levels. Both basal and post-occlusion HbNO levels were significantly correlated with reactive hyperemia (RH) indexes (r = 0.58; P<0.0001 for basal HbNO). Conclusion The study demonstrates quantitative measurements of 5-coordinate α-HbNO in human venous erythrocytes, its dynamic physiologic regulation and correlation with endothelial function measured by tonometry during hyperemia. This opens the way to further understanding of in vivo determinants of NO bioavailability in human circulation. PMID:24130774

  11. Experimental design for reflection measurements of highly reactive liquid or solid substances with application to liquid sodium. [LMFBR

    SciTech Connect

    Chan, S.H.; Gossler, A.A.

    1980-06-30

    This technical report describes the experimental part of a program on thermal radiation properties of reactor materials. A versatile goniometer system with associated electronic components and mechanical instruments has been assembled. It is designed to measure spectral, specular reflectances of highly reactive liquid or solid substances over a spectral range of 0.3 ..mu.. to 9 ..mu.. and incidence angles of 12/sup 0/ to 30/sup 0/ off the normal direction. The capability of measuring reflectances of liquid substances clearly distinguishes this experimental design from conventional systems which are applicable only to solid substances. This design has been used to measure the spectral, specular reflectance of liquid sodium and preliminary results obtained are compared with those of solid sodium measured by other investigators.

  12. Locked-wrap fuel rod

    DOEpatents

    Kaplan, Samuel; Chertock, Alan J.; Punches, James R.

    1977-01-01

    A method for spacing fast reactor fuel rods using a wire wrapper improved by orienting the wire-wrapped fuel rods in a unique manner which introduces desirable performance characteristics not attainable by previous wire-wrapped designs. Use of this method in a liquid metal fast breeder reactor results in: (a) improved mechanical performance, (b) improved rod-to-rod contact, (c) reduced steel volume, and (d) improved thermal-hydraulic performance. The method produces a "locked wrap" design which tends to lock the rods together at each of the wire cluster locations.

  13. SAFETY SYSTEM FOR CONTROL ROD

    DOEpatents

    Paget, J.A.

    1963-05-14

    A structure for monitoring the structural continuity of a control rod foi a neutron reactor is presented. A electric conductor readily breakable under mechanical stress is fastened along the length of the control rod at a plurality of positions and forms a closed circuit with remote electrical components responsive to an open circuit. A portion of the conductor between the control rod and said components is helically wound to allow free and normally unrestricted movement of the segment of conductor secured to the control rod relative to the remote components. Any break in the circuit is indicative of control rod breakage. (AEC)

  14. A measurement of total reactive nitrogen, NOy, together with NO₂, NO, and O₃ via cavity ring-down spectroscopy.

    PubMed

    Wild, Robert J; Edwards, Peter M; Dubé, William P; Baumann, Karsten; Edgerton, Eric S; Quinn, Patricia K; Roberts, James M; Rollins, Andrew W; Veres, Patrick R; Warneke, Carsten; Williams, Eric J; Yuan, Bin; Brown, Steven S

    2014-08-19

    We present a sensitive, compact detector that measures total reactive nitrogen (NOy), as well as NO2, NO, and O3. In all channels, NO2 is directly detected by laser diode based cavity ring-down spectroscopy (CRDS) at 405 nm. Ambient O3 is converted to NO2 in excess NO for the O3 measurement channel. Likewise, ambient NO is converted to NO2 in excess O3. Ambient NOy is thermally dissociated at ∼700 °C to form NO2 or NO in a heated quartz inlet. Any NO present in ambient air or formed from thermal dissociation of other reactive nitrogen compounds is converted to NO2 in excess O3 after the thermal converter. We measured thermal dissociation profiles for six of the major NOy components and compared ambient measurements with other instruments during field campaigns in Utah and Alabama. Alabama measurements were made in a rural location with high biogenic emissions, and Utah measurements were made in the wintertime in unusual conditions that form high ozone levels from emissions related to oil and gas production. The NOy comparison in Alabama, to an accepted standard measurement method (a molybdenum catalytic converter/chemiluminescence instrument), agreed to within 12%, which we define as an upper limit to the accuracy of the NOy channel. The 1σ precision is <30 pptv at 1 s and <4 pptv at 1 min time resolution for all measurement channels. The accuracy is 3% for the NO2 and O3 channels and 5% for the NO channel. The precision and accuracy of this instrument make it a versatile alternative to standard chemiluminescence-based NOy instruments. PMID:25019919

  15. APPARATUS FOR SHEATHING RODS

    DOEpatents

    Ford, W.K.; Wyatt, M.; Plail, S.

    1961-08-01

    An arrangement is described for sealing a solid body of nuclear fuel, such as a uranium metal rod, into a closelyfitting thin metallic sheath with an internal atmosphere of inert gas. The sheathing process consists of subjecting the sheath, loaded with the nuclear fuel body, to the sequential operations of evacuation, gas-filling, drawing (to entrap inert gas and secure close contact between sheath and body), and sealing. (AEC)

  16. Vortices in vibrated granular rods

    NASA Astrophysics Data System (ADS)

    Neicu, Toni; Kudrolli, Arshad

    2002-03-01

    We report the first experimental observation of vortex patterns in granular rods inside a container that is vibrated vertically . The experiments were carried out with an anodized aluminum circular container which is rigidly attached to an electromagnetic shaker and the patterns are imaged using a high-frame rate digital camera. At low rod numbers and driving amplitudes, the rods are observed to lie horizontally. Above a critical number or packing fraction of rods, moving domains of vertical rods are spontaneously observed to form which coexist with horizontal rods. These small domains of vertical rods coarsen over time to form a few large vortices. The size of the vortices increases with the number of rods. We are able to track the ends of the vertical rods and obtain the velocity fields of the vortices. The mean azimuthal velocity as a function of distance from the center of the vortex is obtained as a function of the packing fraction. We will report the phase diagram of the various patterns observed as function of number of rods and driving amplitude. The mechanism for the formation and motion of the domains of vertical rods will be also discussed.

  17. Safety rod latch inspection

    SciTech Connect

    Leader, D.R.

    1992-02-01

    During an attempt to raise control rods from the 100 K reactor in December, one rod could not be withdrawn. Subsequent investigation revealed that a small button'' in the latch mechanism had broken off of the lock plunger'' and was wedged in a position that prevented rod withdrawal. Concern that this failure may have resulted from corrosion or some other metallurgical problem resulted in a request that SRL examine six typical latch mechanisms from the 100 L reactor by use of radiography and metallography. During the examination of the L-Area latches, a failed latch mechanism from the 100 K reactor was added to the investigation. Fourteen latches that had a history of problems were removed from K-Area and sent to SRL for inclusion in this study the week after the original seven assemblies were examined, bringing the total of latch assemblies discussed in this report to twenty one. Results of the examination of the K-Area latch that initiated this study is not included in this report.

  18. Safety rod latch inspection

    SciTech Connect

    Leader, D.R.

    1992-02-01

    During an attempt to raise control rods from the 100 K reactor in December, one rod could not be withdrawn. Subsequent investigation revealed that a small ``button`` in the latch mechanism had broken off of the ``lock plunger`` and was wedged in a position that prevented rod withdrawal. Concern that this failure may have resulted from corrosion or some other metallurgical problem resulted in a request that SRL examine six typical latch mechanisms from the 100 L reactor by use of radiography and metallography. During the examination of the L-Area latches, a failed latch mechanism from the 100 K reactor was added to the investigation. Fourteen latches that had a history of problems were removed from K-Area and sent to SRL for inclusion in this study the week after the original seven assemblies were examined, bringing the total of latch assemblies discussed in this report to twenty one. Results of the examination of the K-Area latch that initiated this study is not included in this report.

  19. Improved instrumentation for near-real-time measurement of reactive hydrocarbons, NO{sub 2}, and peroxyacyl nitrates.

    SciTech Connect

    Drayton, P. J.; Blazer, C. A.; Gaffney, J. S.; Marley, N. A.

    1999-10-06

    The measurement of reactive hydrocarbons and associated nitrogen oxides, NO{sub 2}, and peroxyacyl nitrates (PANs) is of key importance to unraveling the complex chemistries involved in daytime photochemical oxidant formation and nighttime chemistry driven by the nitrate radical. Recent work has demonstrated that chemiluminescent reactions of ozone with hydrocarbons (and the temperature dependence of the reactions) can be used as a means of detecting a wide variety of organic compounds in the gas phase with sensitivity comparable to or better than that of the conventional flame ionization detection method (Marley and Gaffney, 1998). We have implemented a new design and built a new instrument to evaluate this approach for the monitoring of alkenes. This instrument makes use of a computer-controlled photon-counting system with a reaction chamber operated at room temperature. Signals are compared to those for an ethene standard to estimate relative reactivity. The instrument is described in detail here, along with a new version of a luminol-based chemiluminescence detection system with fast gas chromatography for measurement of NO{sub 2} and PANs. The photon-counting system, the reaction chamber, and the luminol detection system have been combined on one instrument rack for field use on both ground-based and aircraft platforms. Data presented show the response times of the instruments and indicate applications for examining reactive hydrocarbon emissions from both vegetation and anthropogenic sources. In addition, the luminol chemiluminescence instrument was field tested, and the data obtained are compared with data from a commercial NO{sub x} analyzer. Preliminary results demonstrating the potential use of this instrumentation for rapid measurement of key tropospheric trace species are presented and discussed.

  20. Passive electrical properties of rod outer segments

    PubMed Central

    Falk, Gertrude; Fatt, P.

    1968-01-01

    1. Measurements on a packed suspension of randomly oriented, dark-adapted frog rods at frequencies of 15 c/s-0·5 Mc/s indicate a behaviour similar to that of other biological materials. 2. Results are analysed on the assumption that the low-frequency limiting resistance is determined by current flowing in the suspending medium and that, of the rods, two thirds are oriented perpendicular to the applied field and one third parallel to it. Those parallel to the field are treated as non-conductors. 3. From the high-frequency limiting resistance the conductivity of the rod interior is calculated to vary linearly with the conductivity of the medium. The slope of the relation of internal to external conductivity is 0·50 with a limiting internal conductivity (at zero external) of 280 μmho/cm. 4. On the assumption that the suspension can be represented as a single-capacitance network, the characteristic frequency of impedance is used to calculate a capacitance for the rod surface of 1·54 μF/cm2. On the assumption of a distribution in properties of the suspension according to the theory of Bruggeman, the capacitance is calculated to have a value of about one half this. 5. At frequencies below 5 kc/s the impedance locus deviates from the curve describing the behaviour at higher frequencies. It is suggested that this may involve conduction in a thin layer extending along the surface of the rod. PMID:5685292

  1. Assessing the Cr(VI) reduction efficiency of a permeable reactive barrier using Cr isotope measurements and 2D reactive transport modeling

    NASA Astrophysics Data System (ADS)

    Wanner, Christoph; Zink, Sonja; Eggenberger, Urs; Mäder, Urs

    2012-04-01

    In Thun, Switzerland, a permeable reactive barrier (PRB) for Cr(VI) reduction by gray cast iron was installed in May 2008. The PRB is composed of a double array of vertical piles containing iron shavings and gravel. The aquifer in Thun is almost saturated with dissolved oxygen and the groundwater flow velocities are ca. 10-15 m/day. Two years after PRB installation Cr(VI) concentrations still permanently exceed the Swiss threshold value for contaminated sites downstream of the barrier at selected localities. Groundwater δ53/52CrSRM979 measurements were used to track Cr(VI) reduction induced by the PRB. δ53/52CrSRM979 values of two samples downstream of the PRB showed a clear fractionation towards more positive values compared to four samples from the hotspot, which is clear evidence of Cr(VI) reduction induced by the PRB. Another downstream sample did not show a shift to more positive δ53/52CrSRM979 values. Because this latter location correlates with the highest downstream Cr(VI) concentration it is proposed that a part of the Cr(VI) plume is bypassing the barrier. Using a Rayleigh fractionation model a minimum present-day overall Cr(VI) reduction efficiency of ca. 15% was estimated. A series of 2D model simulations, including the fractionation of Cr isotopes, confirm that only a PRB bypass of parts of the Cr(VI) plume can lead to the observed values. Additionally, the simulations revealed that the proposed bypass occurs due to an insufficient permeability of the individual PRB piles. It is concluded that with this type of PRB a complete and long-lasting Cr(VI) reduction is extremely difficult to achieve for Cr(VI) contaminations located in nearly oxygen and calcium carbonate saturated aquifer in a regime of high groundwater velocities. Additional remediation action would limit the environmental impact and allow to reach target concentrations.

  2. Gap-junctional coupling of mammalian rod photoreceptors and its effect on visual detection

    PubMed Central

    Li, Peter H.; Verweij, Jan; Long, James H.; Schnapf, Julie L.

    2012-01-01

    The presence of gap junctions between rods in mammalian retina suggests a role for rod-rod coupling in human vision. Rod coupling is known to reduce response variability, but because junctional conductances are not known, the downstream effects on visual performance are uncertain. Here we assessed rod coupling in guinea pig retina by measuring: 1) the variability in responses to dim flashes, 2) Neurobiotin tracer coupling, and 3) junctional conductances. Results were consolidated into an electrical network model and a model of human psychophysical detection. Guinea pig rods form tracer pools of 1 to ~20 rods, with junctional conductances averaging ~350 pS. We calculate that coupling will reduce human dark-adapted sensitivity ~10% by impairing the noise filtering of the synapse between rods and rod bipolar cells. However, coupling also mitigates synaptic saturation and is thus calculated to improve sensitivity when stimuli are spatially restricted or are superimposed over background illumination. PMID:22399777

  3. CRITICAL CONFIGURATION AND PHYSICS MEASUREMENTS FOR GRAPHITE REFLECTED ASSEMBLIES OF U(93.15)O2 FUEL RODS (1.506-CM PITCH)

    SciTech Connect

    Margaret A. Marshall

    2012-03-01

    A series of critical experiments were completed in 1962-1965 at Oak Ridge National Laboratory’s Critical Experiments Facility in support of the Medium-Power Reactor Experiments (MPRE) program. In the late 1950’s efforts were made to study “power plants for the production of electrical power in space vehicles”. The MPRE program was a part of those efforts and studied the feasibility of a stainless steel system, boiling potassium 1 MW(t), or about 140 kW(e), reactor. The program was carried out in [fiscal years] 1964, 1965, and 1966. A summary of the program’s effort was compiled in 1967. The delayed critical experiments were a mockup of a small, potassium-cooled space power reactor for validation of reactor calculations and reactor physics methods. Initial experiments, performed in November and December of 1962, consisted of a core of 253 unmoderated stainless steel tubes, each containing 26 UO2 fuel pellets, surrounded by a graphite reflector. Measurements were made to determine critical reflector arrangements, fission-rate distributions, and cadmium ratio distributions. Subsequent experiments used beryllium reflectors and also measured the reactivity for various materials placed in the core. “The [assemblies were built] on [a] vertical assembly machine so that the movable part was the core and bottom reflector.” The first experiment in the series was evaluated in HEU-COMP-FAST-001. It had the 253 fuel tubes packed tightly into a 22.87 cm outside diameter (OD) core tank (References 1 and 2). The second experiment in the series, performed in early 1963, which is studied in this evaluation, had the 253 fuel tubes at a 1.506-cm triangular lattice in a 25.96 cm OD core tank and graphite reflectors on all sides. The experiment has been determined to represent an acceptable benchmark experiment. Information for this evaluation was compiled from published reports on all three parts of the experimental series (Reference 1-5) and the experimental logbook as

  4. Method and apparatus for monitoring the control rods of a nuclear reactor

    SciTech Connect

    Gravelle, A.; Marini, J.; Romy, D.

    1984-12-04

    Method and apparatus for monitoring the movement of the control rods of a nuclear reactor. The number of steps of movement in either direction of the rod from which the control rod is suspended is counted. According to the height of the step, an indication of the position of the suspension rod and of the control rod. The apparatus comprises devices for measuring the speed of movement of the control rod, for logging variations in speed higher than a given value, and for counting such variations according to their sign. The invention is particularly useful in pressurized water nuclear reactors.

  5. Operation and reactivity measurements of an accelerator driven subcritical TRIGA reactor

    NASA Astrophysics Data System (ADS)

    O'Kelly, David Sean

    Experiments were performed at the Nuclear Engineering Teaching Laboratory (NETL) in 2005 and 2006 in which a 20 MeV linear electron accelerator operating as a photoneutron source was coupled to the TRIGA (Training, Research, Isotope production, General Atomics) Mark II research reactor at the University of Texas at Austin (UT) to simulate the operation and characteristics of a full-scale accelerator driven subcritical system (ADSS). The experimental program provided a relatively low-cost substitute for the higher power and complexity of internationally proposed systems utilizing proton accelerators and spallation neutron sources for an advanced ADSS that may be used for the burning of high-level radioactive waste. Various instrumentation methods that permitted ADSS neutron flux monitoring in high gamma radiation fields were successfully explored and the data was used to evaluate the Stochastic Pulsed Feynman method for reactivity monitoring.

  6. Measurement of Reactive Oxygen Species in the Culture Media Using Acridan Lumigen PS-3 Assay

    PubMed Central

    Uy, Benedict; McGlashan, Susan R.; Shaikh, Shamim B.

    2011-01-01

    Reactive oxygen species (ROS) are generated continuously during aerobic metabolism. ROS are highly reactive molecules and in excessive amounts, can lead to protein and DNA oxidation, protein cross-linking, and cell death. Cell-culture models provide a valuable tool in understanding the mechanisms that lead to cell death. Accumulation of ROS within cells and/or their release into the culture media are highly cell type-specific. The ability to estimate ROS levels in the culture media is an important step in understanding the mechanisms contributing to disease processes. In this paper, we describe the optimization of a simple method to estimate ROS levels in the culture media using the Acridan Lumigen PS-3 reagent provided in the Amersham ECL Plus kit (GE Healthcare, UK). We have shown that the Acridan Lumigen PS-3 assay generates ROS-specific chemiluminescence in fresh as well as media stored at −20°C, in as little as 10–20 μl of samples. The method was able to detect the dose (of stimulants)- and time (acute and chronic)-dependent changes in ROS levels in media collected from various cell types. Our results suggest that the kit reagents, PBS buffer, and various media did not contribute significantly to the overall chemiluminescence generated in the assay; however, we suggest that the unused medium specific for each cell type should be used as blanks and final readings of test samples normalized against these readings. As this method uses commonly available laboratory equipment and commercially available reagents, we believe this assay is convenient, economical, and specific in estimating ROS released extracellularly into the culture media. PMID:21966257

  7. Satellite Remote Sensing of the Reactive Lower Atmosphere Using Medium Resolution Infrared Measurements: Highlights from Iasi Mission

    NASA Astrophysics Data System (ADS)

    Coheur, P. F.

    2013-06-01

    Human activities have significantly altered the equilibrium of the Earth atmosphere. If the steady increase in the concentration of greenhouse gases has attracted most of the attention, it is important as well to monitor the evolution of our "reactive atmosphere", as shorter-lived atmospheric species impact human health and ecosystems directly (e.g. local air quality) or indirectly (e.g. chemistry-climate interactions), through poorly known and quantified processes. Optical instruments on board satellites, and especially those operating in the infrared with sufficient spectral resolution, provide unique opportunity for measuring reactive trace gases in the troposphere and the stratosphere on various scales. The presentation focuses on the measurements of the Infrared Atmospheric Sounding Interferometer IASI onboard Metop satellites. IASI makes global measurements of the Earth atmosphere in a nadir view, i.e. looking downward at the terrestrial radiation, with a horizontal resolution of a few hundreds km^2. It provides more than 10^6 radiance spectra daily, which cover the infrared range between 645 and 2760 cm^{-1} at medium spectral resolution (0.5 cm^{-1} apodized) and low noise. This, coupled to the exceptional sampling performances of IASI, made breakthroughs in the fields of atmospheric spectroscopy and chemistry. In this talk, we will shortly describe IASI instrument and its spectral measurements, as well as the radiative transfer model and retrieval scheme set up for near-real-time processing. We will review the principal accomplishments of IASI in probing the reactive atmosphere by measuring simultaneously the concentrations of about 25 trace species with short (e.g. NH_3, SO_2) to medium (e.g. O_3, CO) residence time, and from the local emission hotspot to the planetary scale. We will put emphasis on the challenging measurements of the polluted planetary boundary layer and will also show a series of focused results on pollution outflow, transport and in

  8. Psychometric Properties of the Affect Intensity and Reactivity Measure Adapted for Youth (AIR-Y)

    ERIC Educational Resources Information Center

    Jones, Rachel E.; Leen-Feldner, Ellen W.; Olatunji, Bunmi O.; Reardon, Laura E.; Hawks, Erin

    2009-01-01

    A valid and reliable instrument for measuring affect intensity does not exist for adolescents; such a measure may help to refine understanding of emotion among youths. The purpose of the current study was to evaluate the psychometric properties and clinical relevance of a measure of affect intensity adapted for youths. Two hundred five community…

  9. Assessing the Cr(VI) reduction efficiency of a permeable reactive barrier using Cr isotope measurements and 2D reactive transport modeling.

    PubMed

    Wanner, Christoph; Zink, Sonja; Eggenberger, Urs; Mäder, Urs

    2012-04-01

    In Thun, Switzerland, a permeable reactive barrier (PRB) for Cr(VI) reduction by gray cast iron was installed in May 2008. The PRB is composed of a double array of vertical piles containing iron shavings and gravel. The aquifer in Thun is almost saturated with dissolved oxygen and the groundwater flow velocities are ca. 10-15m/day. Two years after PRB installation Cr(VI) concentrations still permanently exceed the Swiss threshold value for contaminated sites downstream of the barrier at selected localities. Groundwater δ(53/52)Cr(SRM979) measurements were used to track Cr(VI) reduction induced by the PRB. δ(53/52)Cr(SRM979) values of two samples downstream of the PRB showed a clear fractionation towards more positive values compared to four samples from the hotspot, which is clear evidence of Cr(VI) reduction induced by the PRB. Another downstream sample did not show a shift to more positive δ(53/52)Cr(SRM979) values. Because this latter location correlates with the highest downstream Cr(VI) concentration it is proposed that a part of the Cr(VI) plume is bypassing the barrier. Using a Rayleigh fractionation model a minimum present-day overall Cr(VI) reduction efficiency of ca. 15% was estimated. A series of 2D model simulations, including the fractionation of Cr isotopes, confirm that only a PRB bypass of parts of the Cr(VI) plume can lead to the observed values. Additionally, the simulations revealed that the proposed bypass occurs due to an insufficient permeability of the individual PRB piles. It is concluded that with this type of PRB a complete and long-lasting Cr(VI) reduction is extremely difficult to achieve for Cr(VI) contaminations located in nearly oxygen and calcium carbonate saturated aquifer in a regime of high groundwater velocities. Additional remediation action would limit the environmental impact and allow to reach target concentrations. PMID:22343010

  10. Direct determination of absorption anisotropy in colloidal quantum rods

    NASA Astrophysics Data System (ADS)

    Kamal, John Sundar; Gomes, Raquel; Hens, Zeger; Karvar, Masoumeh; Neyts, Kristiaan; Compernolle, Sien; Vanhaecke, Frank

    2012-01-01

    We propose a direct method to determine absorption anisotropy of colloidal quantum rods. In this method, the rods are aligned in solution by using an alternating electric field and we measure simultaneously the resulting average change in absorption. We show that a frequency window for the electric field exists in which the change in absorbance as a function of field strength can be analyzed in terms of the quantum-rod dipole moment and the absorption coefficient for light that is polarized parallel or perpendicular to the long axis of the rod. The approach is verified by measuring the absorbance change of CdSe rods at 400 nm as a function of field strength, where we demonstrate excellent agreement between experiment and theory. This enables us to propose improved values for the CdSe quantum-rod extinction coefficient. Next, we analyze CdSe/CdS dot-in-rods and find that the absorption of the first exciton transition is fully anisotropic, with a vanishing absorption coefficient for light that is polarized perpendicularly to the long axis of the rods.

  11. Bond of fiber reinforced plastic (FRP) rods to concrete

    SciTech Connect

    Al-Zahrani, M.M.; Nanni, A.; Al-Dulaijan, S.U.; Bakis, C.E.

    1996-11-01

    The bond behavior between FRP rods and concrete is one of the most important aspects to predicting the short- and long-term performance of FRP reinforced concrete structures including development and transfer length. In this research, the direct pull-out test was used to study the FRP/concrete bond behavior. This method allows measurement of the loaded- and free-end slip of the FRP rod and placement of a strain probe inside the rod to measure internal strain distribution in both axial and radial directions along the bonded length without affecting the FRP/concrete interface. Knowledge of strain distribution is necessary to study the load transfer mechanism between FRP rod and concrete. The scope of this paper include experimental results obtained with the direct pull-out test using 12.7 mm glass and carbon FRP rods with smooth and axisymmetrical deformed surfaces. The typical results are given as nominal bond and shear stress vs. free- and loaded-end slip. Experimental results obtained from strain probes used during pull-out tests are also presented as nominal bond and shear stress vs. strain. For smooth rods, friction is the main controlling factor. For deformed rods, bond tends to be controlled by strength and mechanical action of the axisymmetrical deformations rather than adhesion and friction. The strength of concrete appears to have no effect on the bond strength and failure mechanism of these particular machined FRP rods when concrete splitting is avoided.

  12. Reactive transport modelling of a remediation measure at a former gasworks site in Southern Germany

    NASA Astrophysics Data System (ADS)

    Ptak, T.; Herold, M.; Greskowiak, J.; Prommer, H.

    2009-12-01

    The aquifer beneath a former manufactured gas plant site is contaminated with polycyclic and heterocyclic aromatic hydrocarbons that form large plumes and are only slowly degraded under natural conditions. This leaves active remediation as the only viable option to eliminate the risks of toxic substances to reach potential receptors. The aims of the study presented here were to verify the proposed conceptual model of interacting physical and biogeochemical processes and to assess the effectiveness of a proposed in-situ remediation approach with the help of multi-component reactive transport modelling, focusing on the situations (i) prior to the implementation of the in-situ remediation scheme and (ii) following the operation of a circulation well with O2 and H2O2 injection to aid aerobic microbial degradation of the contaminants in the otherwise anoxic surroundings. The model incorporates microbially mediated redox reactions, mineral precipitation/dissolution reactions as well as subsequent changes in the chemical composition of the aquifer. The degradation pathways proposed in the conceptual model could be verified. The model was then used (i) to explore two possible remediation scenarios where the results highlighted the importance of source remediation and (ii) to study the uncertainty regarding the presence of another electron donor in the form of pyrite.

  13. Fiber optic laser rod

    DOEpatents

    Erickson, G.F.

    1988-04-13

    A laser rod is formed from a plurality of optical fibers, each forming an individual laser. Synchronization of the individual fiber lasers is obtained by evanescent wave coupling between adjacent optical fiber cores. The fiber cores are dye-doped and spaced at a distance appropriate for evanescent wave coupling at the wavelength of the selected dye. An interstitial material having an index of refraction lower than that of the fiber core provides the optical isolation for effective lasing action while maintaining the cores at the appropriate coupling distance. 2 figs.

  14. Reactor control rod timing system

    DOEpatents

    Wu, Peter T. K.

    1982-01-01

    A fluid driven jet-edge whistle timing system for control rods of a nuclear reactor for producing real-time detection of the timing of each control rod in its scram operation. An important parameter in reactor safety, particularly for liquid metal fast breeder reactors (LMFBR), is the time deviation between the time the control rod is released and the time the rod actually reaches the down position. The whistle has a nearly pure tone signal with center frequency (above 100 kHz) far above the frequency band in which the energy of the background noise is concentrated. Each control rod can be fitted with a whistle with a different frequency so that there is no ambiguity in differentiating the signal from each control rod.

  15. Making Highly Pure Glass Rods

    NASA Technical Reports Server (NTRS)

    Naumann, R. J.

    1986-01-01

    Proposed quasi-containerless method for making glass rods or fibers minimizes contact between processing equipment and product. Method allows greater range of product sizes and shapes than achieved in experiments on containerless processing. Molten zone established in polycrystalline rod. Furnace sections separated, and glass rod solidifies between them. Clamp supports solid glass as it grows in length. Pulling clamp rapidly away from melt draws glass fiber. Fiber diameter controlled by adjustment of pulling rate.

  16. Automatic safety rod for reactors

    DOEpatents

    Germer, John H.

    1988-01-01

    An automatic safety rod for a nuclear reactor containing neutron absorbing material and designed to be inserted into a reactor core after a loss-of-core flow. Actuation is based upon either a sudden decrease in core pressure drop or the pressure drop decreases below a predetermined minimum value. The automatic control rod includes a pressure regulating device whereby a controlled decrease in operating pressure due to reduced coolant flow does not cause the rod to drop into the core.

  17. Airflow produced by dielectric barrier discharge between asymmetric parallel rod electrodes

    SciTech Connect

    Hayashi, Kazuo; Tanaka, Motofumi; Yasui, Hiroyuki; Hashimoto, Kiyoshi

    2007-09-15

    We observed a novel type of airflow produced by an atmospheric rf discharge between asymmetric parallel rod electrodes. The electrodes were a bare metal rod 1 mm in diameter and a glass-coated metal rod 3.2 mm in diameter. The thrust, measured by a pendulum, increased with discharge input power.

  18. Quasi-static vapor pressure measurements on reactive systems in inert atmosphere box

    NASA Technical Reports Server (NTRS)

    Fischer, A. K.

    1968-01-01

    Apparatus makes vapor pressure measurements on air-sensitive systems in an inert atmosphere glove box. Once the apparatus is loaded with the sample and all connections made, all measuring operations may be performed outside the box. The apparatus is a single-tube adaptation of the double-tube quasi-static technique.

  19. Effect of blocking the Na+/K+ ATPase on Ca2+ extrusion and light adaptation in mammalian retinal rods.

    PubMed Central

    Demontis, G C; Ratto, G M; Bisti, S; Cervetto, L

    1995-01-01

    Membrane current and light response were recorded from rods of monkey and guinea pig by means of suction electrodes. The correlation between adaptation and the Na+/K+ pump was investigated by measuring light-dependent changes in sensitivity with and without inhibition of Na+/K+ ATPase by strophanthidin. Strophanthidin was found to reduce the dark current, to slow the time course of the photoresponse, and to increase light sensitivity. At concentrations between 20 and 500 nM, the pump inhibitor suppressed in a reversible way the current re-activation occurring during prolonged illumination and modified the light-dependent decrease in sensitivity, which in control conditions approximates to a Weber-Fechner function. The effects of the pump inhibitor on the adaptive properties of rods are associated with an increased time constant of the membrane current attributed to the operation of the Na+:Ca2+,K+ exchanger. The effects of rapid application of the pump inhibitor on the current re-activation are consistent with the idea that significant changes in the internal sodium occur in rods of mammals during background illumination and that they play an important role in the process of light adaptation. PMID:8527658

  20. Piston and connecting rod assembly

    NASA Technical Reports Server (NTRS)

    Brogdon, James William (Inventor); Gill, David Keith (Inventor); Chatten, John K. (Inventor)

    2001-01-01

    A piston and connecting rod assembly includes a piston crown, a piston skirt, a connecting rod, and a bearing insert. The piston skirt is a component separate from the piston crown and is connected to the piston crown to provide a piston body. The bearing insert is a component separate from the piston crown and the piston skirt and is fixedly disposed within the piston body. A bearing surface of a connecting rod contacts the bearing insert to thereby movably associate the connecting rod and the piston body.

  1. Measurement and modelling of reactive transport in geological barriers for nuclear waste containment.

    PubMed

    Xiong, Qingrong; Joseph, Claudia; Schmeide, Katja; Jivkov, Andrey P

    2015-11-11

    Compacted clays are considered as excellent candidates for barriers to radionuclide transport in future repositories for nuclear waste due to their very low hydraulic permeability. Diffusion is the dominant transport mechanism, controlled by a nano-scale pore system. Assessment of the clays' long-term containment function requires adequate modelling of such pore systems and their evolution. Existing characterisation techniques do not provide complete pore space information for effective modelling, such as pore and throat size distributions and connectivity. Special network models for reactive transport are proposed here using the complimentary character of the pore space and the solid phase. This balances the insufficient characterisation information and provides the means for future mechanical-physical-chemical coupling. The anisotropy and heterogeneity of clays is represented using different length parameters and percentage of pores in different directions. Resulting networks are described as mathematical graphs with efficient discrete calculus formulation of transport. Opalinus Clay (OPA) is chosen as an example. Experimental data for the tritiated water (HTO) and U(vi) diffusion through OPA are presented. Calculated diffusion coefficients of HTO and uranium species are within the ranges of the experimentally determined data in different clay directions. This verifies the proposed pore network model and validates that uranium complexes are diffusing as neutral species in OPA. In the case of U(vi) diffusion the method is extended to account for sorption and convection. Rather than changing pore radii by coarse grained mathematical formula, physical sorption is simulated in each pore, which is more accurate and realistic. PMID:26524292

  2. Measurements of reactive nitrogen oxides (NO/y/) within and above a tropical forest canopy in the wet season

    NASA Technical Reports Server (NTRS)

    Bakwin, Peter S.; Wofsy, Steven C.; Fan, Song-Miao

    1990-01-01

    Measurements of ambient concentrations of reactive nitrogen oxides were made in the Amazon rain forest, near Manaus, Brazil, continuously at 39 m (above the canopy), and on several days and nights at 19 m (within the canopy). Concentrations were very low, typically 100-700 pptv, except for brief periods when up to 5000 pptv of NO(y) was observed, indicating polluted air from the urban area of Manaus. The forest was a net sink for NO(y) with the NO(y) flux = -7.6 + or - 5.0) x 10 to the 9th molecules/sq cm per sec in unpolluted periods, even though soils emitted NO at a significant rate (8.9 + or - 1.5 x 10 to the 9th molecules/sq cm per sec). The deposition rate for NO(y) appeared to be much larger during the daytime than at night, suggesting that uptake was controlled either by plant processes (stomatal opening) or by supply of reactive components of NO(y) (e.g., HNO3) during the daytime. Implications for regional and global atmospheric chemistry are discussed.

  3. Measurement of the atmospheric reactivity of emissions from gasoline and alternative-fueled vehicles: Assessment of available methodologies. Part 1. Indoor smog chamber study of reactivity. Final report for the first year, January 1-December 31, 1993

    SciTech Connect

    Kelly, N.A.; Wang, P.; Japar, S.M.; Hurley, M.D.; Wallington, T.J.

    1994-06-30

    A set of multiple indoor smog chambers were used to measure the increase in smog formation (smog = NO oxidation + O3 formation) from a series of individual test volatile organic compounds (VOC`s), as well as carbon monoxide (CO), when they were added to a standard urban mixture and irradiated for 10-12 hours with a solar simulator. The chambers and the mixtures were designed to simulate the Carter incremental reactivity concept that is being used in California. The test compounds covered a wide range of mechanistic uncertainties and predicted reactivities (reactivity is the increase in smog divided by the amount of test compound added). Also, the chambers were used to test the recently developed Integrated Empirical Rate (IER) Model which predicts that the smog formation of a mixture is constant and independent of NOx in the so-called light-limited regime.

  4. HTGR green rod intercomparison. I. Hydrogen assay

    SciTech Connect

    Meier, M.M.; Adams, E.L.

    1981-01-01

    A /sup 252/Cf hydrogen monitor has been used to determine the hydrogen content of each of the 144 unfired (green) fuel rods being circulated in the New Brunswick Laboratory fuel measurement evaluation program. The monitor was calibrated with standards fabricated by Los Alamos Scientific Laboratory (LASL) Analytical Chemistry Group, CMB-1. Measurements were made relative to these standards and overall accuracies of +-3% were achieved.

  5. Measurement of d15 in Fe100-xGax (x=12.5,15,18.4,22), Fe50Co50, and Fe81Al19 highly textured polycrystalline rods

    NASA Astrophysics Data System (ADS)

    Restorff, J. B.; Wun-Fogle, M.; Clark, A. E.

    2008-04-01

    We report the first measurements of d15, which relate torsion to an applied field, in the high magnetostriction Galfenol alloys Fe100-xGax (x=12.5,15,18.4,22), Fe50Co50, and Fe81Al19. Measurements were performed on highly textured polycrystalline 6.4×50.8mm2 rods by simultaneously applying a longitudinal magnetic field H∥ (-1200rod axis and a circumferential magnetic field H⊥ generated by a current i (-60measurements did not yield a value. For Fe50Co50, d15=29±4 and for Fe81Al19, d15=8±1. Estimated values of λ111 were obtained by fitting ξ to 1/H∥ and are compared to those obtained from single crystal measurements.

  6. A large OH sink in summertime surface air of the northern Indo-Gangetic plain revealed through in-situ total OH Reactivity measurements

    NASA Astrophysics Data System (ADS)

    Kumar, V.; Garg, S.; Chandra, P.; Sinha, V.

    2013-12-01

    The summertime surface air in the Northern Indo-Gangetic plain is characterized by high temperatures (up to 47 oC) and strong solar radiation (up to 765 Watt/m2), which together with large urban and agricultural emissions in the densely populated region, lead to intense photochemistry. The hydroxyl radical (OH) is the primary atmospheric oxidant responsible for oxidizing gaseous emissions and hence direct measurements of the total OH reactivity are necessary for understanding reactive emission budgets and constraining instantaneous ozone production regimes. Here, we present the first dataset of direct OH reactivity measurements from a regional surface site in the northern India-Gangetic plain (30.667°N, 76.729°E; 310 m above mean sea level). The measurements were performed in April-May 2013 using the comparative reactivity method [1]. A single PTRMS was used for sequential measurements of the total OH reactivity and circa 20 ambient VOCs. Nitrogen oxides (NO and NO2), sulphur dioxide, carbon monoxide, ozone and meteorological parameters were measured concomitantly using the IISER Mohali atmospheric chemistry facility. Air masses impacting the site arrived from rural and agricultural regions at high wind speeds of up to 24 m/s. A large variability was observed in the diel hourly averaged OH reactivity spanning an interquartile range of 36 s-1 - 120 s-1. The daily average and median total OH reactivity was 76 s-1 and 73 s-1, respectively corresponding to average and median OH chemical lifetimes of 13.1 milliseconds and 13.6 milliseconds, respectively. The five highest individual OH sinks measured were: acetaldehyde > isoprene+furan > NO2 > trimethyl benzene > CO. The measured OH reactivity did not show a pronounced diel cycle but remarkably the highest missing OH reactivity fraction (> 50 %) was observed during afternoon hours (12-16 local time) on very sunny days with low RH. This suggests that a significant fraction of secondary oxidation products formed due to

  7. Measurements of gas phase reactive nitrogen during two wildfires in Colorado

    NASA Astrophysics Data System (ADS)

    Prenni, A. J.; Chen, X.; Hecobian, A.; Kreidenweis, S. M.; Collett, J. L.; Schichtel, B. A.

    2012-12-01

    Biomass burning represents an important source of particles and trace gases to the global atmosphere. In addition to carbon species, nitrogen compounds are abundant in biomass burning emissions, with NOx, N2O, and N2 released primarily during flaming combustion, and NH3, amines and nitriles associated with smoldering combustion. Although nitrogen emissions from fires have been documented from laboratory and satellite measurements, and during prescribed burns, few direct measurements have been made during major wildfires. In this presentation, we summarize measurements of gas-phase nitrogen species observed during two wildfires in northern Colorado in 2012: the Hewlett Gulch Fire and High Park Fire. The Hewlett Gulch Fire was directly northwest of Fort Collins, CO and covered 3,100 hectares, while the High Park fire was significantly larger (35,300 hectares), encompassing the Hewlett Gulch Fire and coming within 3-4 km of our laboratory at Colorado State University. Emissions from both fires reached our laboratory, where measurements were made of NOx, NOy, NH3, and additional, unspeciated gas-phase nitrogen compounds. Smoke impacts at our facility ranged from background conditions to periods with very heavy smoke, depending on the local meteorology. We observed dramatic increases in measured concentrations during periods influenced by the fires.

  8. Evaluation of a catalytic reduction technique for the measurement of total reactive odd-nitrogen NOy in the atmosphere

    NASA Technical Reports Server (NTRS)

    Fahey, D. W.; Eubank, C. S.; Hubler, C. S.; Fehsenfeld, F. C.

    1985-01-01

    The suitability of a technique for the measurement of total reactive odd-nitrogen NOy-containing species in the atmosphere has been examined. In the technique, an NOy component species, which may include NO, NO2, NO3, HNO3, peroxyacetyl nitrate, and particulate nitrate, are catalytically reduced by CO to form NO molecules on the surface of a metal converter tube, and the NO product is detected by chemiluminescence produced in reaction with O3. Among the catalysts tested in the temperature range of 25-500 C, Au was the preferred catalyst. The results of laboratory tests investigating the effects of pressure, O3, and H2O on NOy conversion, and the possible sources of interference, have shown that the technique is suitable for atmospheric analyses. The results of a test in ambient air at a remote ground-based field site are included.

  9. Analytical modeling of the buffeting of a rod in axial flow. [PWR; BWR

    SciTech Connect

    Lin, W.H.; Wamsganss, M.W.

    1981-12-01

    Turbulent buffeting of a circular, flexible rod in axial flows is reported. The main excitation mechanisms are turbulent wall-pressure fluctuations and the motion-dependent force field caused by the rod motion. On the assumption that the turbulent wall-pressure fluctuations are independent of rod motion, a linear forced vibration model is proposed to compute the buffeting displacement of the rod with the aid of empirical constants determined from experimental measurements of wall-pressure fluctuations. Predicted and measured values of the root-mean-square rod displacement are shown to be in reasonably good agreement.

  10. The Weird World, and Equally Weird Measurement Models: Reactive Indicators and the Validity Revolution

    ERIC Educational Resources Information Center

    Hayduk, Leslie A.; Robinson, Hannah Pazderka; Cummings, Greta G.; Boadu, Kwame; Verbeek, Eric L.; Perks, Thomas A.

    2007-01-01

    Researchers using structural equation modeling (SEM) aspire to learn about the world by seeking models with causal specifications that match the causal forces extant in the world. This quest for a model matching existing worldly causal forces constitutes an ontology that orients, or perhaps reorients, thinking about measurement validity. This…