When experiment and energy conservation collide: video analysis of an unrolling mat

NASA Astrophysics Data System (ADS)

Mungan, Carl E.; Lipscombe, Trevor C.

2018-03-01

A mat consisting of round bamboo rods connected by strings perpendicular to their axes unrolls without slipping on a horizontal table. Video analysis is used to measure the position of the centre of the remaining roll as a function of time. It is found to accelerate with time due to the ‘rocket effect’ of the roll ejecting rods backward relative to itself. Mechanical energy is not conserved because of the inelastic collisions of the rods with the table. The fitted coefficient of restitution (COR) is 0.59 ± 0.04 which is consistent with known values for wood on wood. In support of this explanation, progressively smaller values of the COR are found when the mat is unrolled on a flat woven rug and on a shock-absorbing pad. The level of analysis is appropriate to an undergraduate course in physical mechanics.

Benchmarking the SPHINX and CTH shock physics codes for three problems in ballistics

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

Wilson, L.T.; Hertel, E.; Schwalbe, L.

1998-02-01

The CTH Eulerian hydrocode, and the SPHINX smooth particle hydrodynamics (SPH) code were used to model a shock tube, two long rod penetrations into semi-infinite steel targets, and a long rod penetration into a spaced plate array. The results were then compared to experimental data. Both SPHINX and CTH modeled the one-dimensional shock tube problem well. Both codes did a reasonable job in modeling the outcome of the axisymmetric rod impact problem. Neither code correctly reproduced the depth of penetration in both experiments. In the 3-D problem, both codes reasonably replicated the penetration of the rod through the first plate.more » After this, however, the predictions of both codes began to diverge from the results seen in the experiment. In terms of computer resources, the run times are problem dependent, and are discussed in the text.« less

Halloysite-derived nitrogen doped carbon electrocatalysts for anion exchange membrane fuel cells

NASA Astrophysics Data System (ADS)

Lu, Yaxiang; Wang, Lianqin; Preuß, Kathrin; Qiao, Mo; Titirici, Maria-Magdalena; Varcoe, John; Cai, Qiong

2017-12-01

Developing the low-cost, highly active carbonaceous materials for oxygen reduction reaction (ORR) catalysts has been a high-priority research direction for durable fuel cells. In this paper, two novel N-doped carbonaceous materials with flaky and rod-like morphology using the natural halloysite as template are obtained from urea nitrogen source as well as glucose (denoted as GU) and furfural (denoted as FU) carbon precursors, respectively, which can be directly applied as metal-free electrocatalysts for ORR in alkaline electrolyte. Importantly, compared with a benchmark Pt/C (20wt%) catalyst, the as-prepared carbon catalysts demonstrate higher retention in diffusion limiting current density (after 3000 cycles) and enhanced methanol tolerances with only 50-60mV negative shift in half-wave potentials. In addition, electrocatalytic activity, durability and methanol tolerant capability of the two N-doped carbon catalysts are systematically evaluated, and the underneath reasons of the outperformance of rod-like catalysts over the flaky are revealed. At last, the produced carbonaceous catalysts are also used as cathodes in the single cell H2/O2 anion exchange membrane fuel cell (AEMFC), in which the rod-like FU delivers a peak power density as high as 703 mW cm-2 (vs. 1106 mW cm-2 with a Pt/C benchmark cathode catalyst).

HTR-PROTEUS pebble bed experimental program cores 9 & 10: columnar hexagonal point-on-point packing with a 1:1 moderator-to-fuel pebble ratio

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

Bess, John D.

2014-03-01

PROTEUS is a zero-power research reactor based on a cylindrical graphite annulus with a central cylindrical cavity. The graphite annulus remains basically the same for all experimental programs, but the contents of the central cavity are changed according to the type of reactor being investigated. Through most of its service history, PROTEUS has represented light-water reactors, but from 1992 to 1996 PROTEUS was configured as a pebble-bed reactor (PBR) critical facility and designated as HTR-PROTEUS. The nomenclature was used to indicate that this series consisted of High Temperature Reactor experiments performed in the PROTEUS assembly. During this period, seventeen criticalmore » configurations were assembled and various reactor physics experiments were conducted. These experiments included measurements of criticality, differential and integral control rod and safety rod worths, kinetics, reaction rates, water ingress effects, and small sample reactivity effects (Ref. 3). HTR-PROTEUS was constructed, and the experimental program was conducted, for the purpose of providing experimental benchmark data for assessment of reactor physics computer codes. Considerable effort was devoted to benchmark calculations as a part of the HTR-PROTEUS program. References 1 and 2 provide detailed data for use in constructing models for codes to be assessed. Reference 3 is a comprehensive summary of the HTR-PROTEUS experiments and the associated benchmark program. This document draws freely from these references. Only Cores 9 and 10 are evaluated in this benchmark report due to similarities in their construction. The other core configurations of the HTR-PROTEUS program are evaluated in their respective reports as outlined in Section 1.0. Cores 9 and 10 were evaluated and determined to be acceptable benchmark experiments.« less

HTR-PROTEUS PEBBLE BED EXPERIMENTAL PROGRAM CORES 5, 6, 7, & 8: COLUMNAR HEXAGONAL POINT-ON-POINT PACKING WITH A 1:2 MODERATOR-TO-FUEL PEBBLE RATIO

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

John D. Bess

2013-03-01

PROTEUS is a zero-power research reactor based on a cylindrical graphite annulus with a central cylindrical cavity. The graphite annulus remains basically the same for all experimental programs, but the contents of the central cavity are changed according to the type of reactor being investigated. Through most of its service history, PROTEUS has represented light-water reactors, but from 1992 to 1996 PROTEUS was configured as a pebble-bed reactor (PBR) critical facility and designated as HTR-PROTEUS. The nomenclature was used to indicate that this series consisted of High Temperature Reactor experiments performed in the PROTEUS assembly. During this period, seventeen criticalmore » configurations were assembled and various reactor physics experiments were conducted. These experiments included measurements of criticality, differential and integral control rod and safety rod worths, kinetics, reaction rates, water ingress effects, and small sample reactivity effects (Ref. 3). HTR-PROTEUS was constructed, and the experimental program was conducted, for the purpose of providing experimental benchmark data for assessment of reactor physics computer codes. Considerable effort was devoted to benchmark calculations as a part of the HTR-PROTEUS program. References 1 and 2 provide detailed data for use in constructing models for codes to be assessed. Reference 3 is a comprehensive summary of the HTR-PROTEUS experiments and the associated benchmark program. This document draws freely from these references. Only Cores 9 and 10 are evaluated in this benchmark report due to similarities in their construction. The other core configurations of the HTR-PROTEUS program are evaluated in their respective reports as outlined in Section 1.0. Cores 9 and 10 were evaluated and determined to be acceptable benchmark experiments.« less

HTR-PROTEUS PEBBLE BED EXPERIMENTAL PROGRAM CORES 9 & 10: COLUMNAR HEXAGONAL POINT-ON-POINT PACKING WITH A 1:1 MODERATOR-TO-FUEL PEBBLE RATIO

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

John D. Bess

2013-03-01

PROTEUS is a zero-power research reactor based on a cylindrical graphite annulus with a central cylindrical cavity. The graphite annulus remains basically the same for all experimental programs, but the contents of the central cavity are changed according to the type of reactor being investigated. Through most of its service history, PROTEUS has represented light-water reactors, but from 1992 to 1996 PROTEUS was configured as a pebble-bed reactor (PBR) critical facility and designated as HTR-PROTEUS. The nomenclature was used to indicate that this series consisted of High Temperature Reactor experiments performed in the PROTEUS assembly. During this period, seventeen criticalmore » configurations were assembled and various reactor physics experiments were conducted. These experiments included measurements of criticality, differential and integral control rod and safety rod worths, kinetics, reaction rates, water ingress effects, and small sample reactivity effects (Ref. 3). HTR-PROTEUS was constructed, and the experimental program was conducted, for the purpose of providing experimental benchmark data for assessment of reactor physics computer codes. Considerable effort was devoted to benchmark calculations as a part of the HTR-PROTEUS program. References 1 and 2 provide detailed data for use in constructing models for codes to be assessed. Reference 3 is a comprehensive summary of the HTR-PROTEUS experiments and the associated benchmark program. This document draws freely from these references. Only Cores 9 and 10 are evaluated in this benchmark report due to similarities in their construction. The other core configurations of the HTR-PROTEUS program are evaluated in their respective reports as outlined in Section 1.0. Cores 9 and 10 were evaluated and determined to be acceptable benchmark experiments.« less

Gadolinia depletion analysis by CASMO-4

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

Kobayashi, Y.; Saji, E.; Toba, A.

1993-01-01

CASMO-4 is the most recent version of the lattice physics code CASMO introduced by Studsvik. The principal aspects of the CASMO-4 model that differ from the models in previous CASMO versions are as follows: (1) heterogeneous model for two-dimensional transport theory calculations; and (2) microregion depletion model for burnable absorbers, such as gadolinia. Of these aspects, the first has previously been benchmarked against measured data of critical experiments and Monte Carlo calculations, verifying the high degree of accuracy. To proceed with CASMO-4 benchmarking, it is desirable to benchmark the microregion depletion model, which enables CASMO-4 to calculate gadolinium depletion directlymore » without the need for precalculated MICBURN cross-section data. This paper presents the benchmarking results for the microregion depletion model in CASMO-4 using the measured data of depleted gadolinium rods.« less

Material test machine for tension-compression tests at high temperature

DOEpatents

Cioletti, Olisse C.

1988-01-01

Apparatus providing a device for testing the properties of material specimens at high temperatures and pressures in controlled water chemistries includes, inter alia, an autoclave housing the specimen which is being tested. The specimen is connected to a pull rod which couples out of the autoclave to an external assembly which includes one or more transducers, a force balance chamber and a piston type actuator. The pull rod feeds through the force balance chamber and is compensated thereby for the pressure conditions existing within the autoclave and tending to eject the pull rod therefrom. The upper end of the push rod is connected to the actuator through elements containing a transducer comprising a linear variable differential transformer (LVDT). The housing and coil assembly of the LVDT is coupled to a tube which runs through a central bore of the pull rod into the autoclave where it is connected to one side of the specimen. The movable core of the LVDT is coupled to a stem which runs through the tube where it is then connected to the other side of the specimen through a coupling member. A transducer in the form of a load cell including one or more strain gages is located on a necked-down portion of the upper part of the pull rod intermediate the LVDT and force balance chamber.

Benchmark tests of JENDL-3.2 for thermal and fast reactors

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

Takano, Hideki; Akie, Hiroshi; Kikuchi, Yasuyuki

1994-12-31

Benchmark calculations for a variety of thermal and fast reactors have been performed by using the newly evaluated JENDL-3 Version-2 (JENDL-3.2) file. In the thermal reactor calculations for the uranium and plutonium fueled cores of TRX and TCA, the k{sub eff} and lattice parameters were well predicted. The fast reactor calculations for ZPPR-9 and FCA assemblies showed that the k{sub eff} reactivity worths of Doppler, sodium void and control rod, and reaction rate distribution were in a very good agreement with the experiments.

HTR-PROTEUS Pebble Bed Experimental Program Cores 1, 1A, 2, and 3: Hexagonal Close Packing with a 1:2 Moderator-to-Fuel Pebble Ratio

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

John D. Bess; Barbara H. Dolphin; James W. Sterbentz

2013-03-01

In its deployment as a pebble bed reactor (PBR) critical facility from 1992 to 1996, the PROTEUS facility was designated as HTR-PROTEUS. This experimental program was performed as part of an International Atomic Energy Agency (IAEA) Coordinated Research Project (CRP) on the Validation of Safety Related Physics Calculations for Low Enriched HTGRs. Within this project, critical experiments were conducted for graphite moderated LEU systems to determine core reactivity, flux and power profiles, reaction-rate ratios, the worth of control rods, both in-core and reflector based, the worth of burnable poisons, kinetic parameters, and the effects of moisture ingress on these parameters.more » Four benchmark experiments were evaluated in this report: Cores 1, 1A, 2, and 3. These core configurations represent the hexagonal close packing (HCP) configurations of the HTR-PROTEUS experiment with a moderator-to-fuel pebble ratio of 1:2. Core 1 represents the only configuration utilizing ZEBRA control rods. Cores 1A, 2, and 3 use withdrawable, hollow, stainless steel control rods. Cores 1 and 1A are similar except for the use of different control rods; Core 1A also has one less layer of pebbles (21 layers instead of 22). Core 2 retains the first 16 layers of pebbles from Cores 1 and 1A and has 16 layers of moderator pebbles stacked above the fueled layers. Core 3 retains the first 17 layers of pebbles but has polyethylene rods inserted between pebbles to simulate water ingress. The additional partial pebble layer (layer 18) for Core 3 was not included as it was used for core operations and not the reported critical configuration. Cores 1, 1A, 2, and 3 were determined to be acceptable benchmark experiments.« less

HTR-PROTEUS Pebble Bed Experimental Program Cores 1, 1A, 2, and 3: Hexagonal Close Packing with a 1:2 Moderator-to-Fuel Pebble Ratio

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

John D. Bess; Barbara H. Dolphin; James W. Sterbentz

2012-03-01

In its deployment as a pebble bed reactor (PBR) critical facility from 1992 to 1996, the PROTEUS facility was designated as HTR-PROTEUS. This experimental program was performed as part of an International Atomic Energy Agency (IAEA) Coordinated Research Project (CRP) on the Validation of Safety Related Physics Calculations for Low Enriched HTGRs. Within this project, critical experiments were conducted for graphite moderated LEU systems to determine core reactivity, flux and power profiles, reaction-rate ratios, the worth of control rods, both in-core and reflector based, the worth of burnable poisons, kinetic parameters, and the effects of moisture ingress on these parameters.more » Four benchmark experiments were evaluated in this report: Cores 1, 1A, 2, and 3. These core configurations represent the hexagonal close packing (HCP) configurations of the HTR-PROTEUS experiment with a moderator-to-fuel pebble ratio of 1:2. Core 1 represents the only configuration utilizing ZEBRA control rods. Cores 1A, 2, and 3 use withdrawable, hollow, stainless steel control rods. Cores 1 and 1A are similar except for the use of different control rods; Core 1A also has one less layer of pebbles (21 layers instead of 22). Core 2 retains the first 16 layers of pebbles from Cores 1 and 1A and has 16 layers of moderator pebbles stacked above the fueled layers. Core 3 retains the first 17 layers of pebbles but has polyethylene rods inserted between pebbles to simulate water ingress. The additional partial pebble layer (layer 18) for Core 3 was not included as it was used for core operations and not the reported critical configuration. Cores 1, 1A, 2, and 3 were determined to be acceptable benchmark experiments.« less

Effects of Energetic and Inert Nano Particles on Burning Liquid Ethanol Droplets

NASA Astrophysics Data System (ADS)

Plascencia, Miguel; Sim, Hyung Sub; Vargas, Andres; Smith, Owen; Karagozian, Ann

2017-11-01

This study explores the effects of nano particulate additives on ethanol fuel droplet combustion in a quiescent environment. Two different types of droplet combustion experiments were performed: one involving the classic single droplet suspended from a quartz fiber and the other involving a burning droplet that has continual fuel delivery via a quartz capillary. Two alternative nano particles were explored here to demonstrate the effect of energetic additives: reactive nano aluminum (nAl) and inert nano silicon dioxide (nSiO2), each with average diameter 80 nm. Simultaneous high speed visible and OH* chemiluminescence images were taken to determine burning rate constants (K) and to study flame and droplet characteristics with varying particulate concentrations. Particle/vapor ejections were seen in continuously fed droplet experiments, while rod-suspended burning droplets showed limited particle ejection. The nSiO2 -laden, rod-suspended droplets formed a porous, shell-like structure resembling the shape of a droplet at higher nSiO2 concentrations, in contrast to smaller residue structures for nAl-laden droplets. Changes in K depended on concentrations of nAl and nSiO2 as well as the method of droplet formation, and TEM images of particle residue revealed additional insights. Supported by AFOSR Grant FA9550-15-1-0339.

Parareal in time 3D numerical solver for the LWR Benchmark neutron diffusion transient model

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

Baudron, Anne-Marie, E-mail: anne-marie.baudron@cea.fr; CEA-DRN/DMT/SERMA, CEN-Saclay, 91191 Gif sur Yvette Cedex; Lautard, Jean-Jacques, E-mail: jean-jacques.lautard@cea.fr

2014-12-15

In this paper we present a time-parallel algorithm for the 3D neutrons calculation of a transient model in a nuclear reactor core. The neutrons calculation consists in numerically solving the time dependent diffusion approximation equation, which is a simplified transport equation. The numerical resolution is done with finite elements method based on a tetrahedral meshing of the computational domain, representing the reactor core, and time discretization is achieved using a θ-scheme. The transient model presents moving control rods during the time of the reaction. Therefore, cross-sections (piecewise constants) are taken into account by interpolations with respect to the velocity ofmore » the control rods. The parallelism across the time is achieved by an adequate use of the parareal in time algorithm to the handled problem. This parallel method is a predictor corrector scheme that iteratively combines the use of two kinds of numerical propagators, one coarse and one fine. Our method is made efficient by means of a coarse solver defined with large time step and fixed position control rods model, while the fine propagator is assumed to be a high order numerical approximation of the full model. The parallel implementation of our method provides a good scalability of the algorithm. Numerical results show the efficiency of the parareal method on large light water reactor transient model corresponding to the Langenbuch–Maurer–Werner benchmark.« less

New core-reflector boundary conditions for transient nodal reactor calculations

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

Lee, E.K.; Kim, C.H.; Joo, H.K.

1995-09-01

New core-reflector boundary conditions designed for the exclusion of the reflector region in transient nodal reactor calculations are formulated. Spatially flat frequency approximations for the temporal neutron behavior and two types of transverse leakage approximations in the reflector region are introduced to solve the transverse-integrated time-dependent one-dimensional diffusion equation and then to obtain relationships between net current and flux at the core-reflector interfaces. To examine the effectiveness of new core-reflector boundary conditions in transient nodal reactor computations, nodal expansion method (NEM) computations with and without explicit representation of the reflector are performed for Laboratorium fuer Reaktorregelung und Anlagen (LRA) boilingmore » water reactor (BWR) and Nuclear Energy Agency Committee on Reactor Physics (NEACRP) pressurized water reactor (PWR) rod ejection kinetics benchmark problems. Good agreement between two NEM computations is demonstrated in all the important transient parameters of two benchmark problems. A significant amount of CPU time saving is also demonstrated with the boundary condition model with transverse leakage (BCMTL) approximations in the reflector region. In the three-dimensional LRA BWR, the BCMTL and the explicit reflector model computations differ by {approximately}4% in transient peak power density while the BCMTL results in >40% of CPU time saving by excluding both the axial and the radial reflector regions from explicit computational nodes. In the NEACRP PWR problem, which includes six different transient cases, the largest difference is 24.4% in the transient maximum power in the one-node-per-assembly B1 transient results. This difference in the transient maximum power of the B1 case is shown to reduce to 11.7% in the four-node-per-assembly computations. As for the computing time, BCMTL is shown to reduce the CPU time >20% in all six transient cases of the NEACRP PWR.« less

75 FR 16439 - Certain Welded Carbon Steel Standard Pipe From Turkey: Preliminary Results of Countervailing Duty...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-04-01

... of businesses, which the GOK deemed ``harmful to juveniles, affecting public morals, certain private... (August 30, 2002), and accompanying Issues and Decision Memorandum (Wire Rod Memorandum) at ``Benchmark... from Turkey, 71 FR 43111 (July 31, 2006) (2004 Pipe Final), and accompanying Issues and Decision...

BODYFIT-1FE: a computer code for three-dimensional steady-state/transient single-phase rod-bundle thermal-hydraulic analysis. Draft report

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

Chen, B.C.J.; Sha, W.T.; Doria, M.L.

1980-11-01

The governing equations, i.e., conservation equations for mass, momentum, and energy, are solved as a boundary-value problem in space and an initial-value problem in time. BODYFIT-1FE code uses the technique of boundary-fitted coordinate systems where all the physical boundaries are transformed to be coincident with constant coordinate lines in the transformed space. By using this technique, one can prescribe boundary conditions accurately without interpolation. The transformed governing equations in terms of the boundary-fitted coordinates are then solved by using implicit cell-by-cell procedure with a choice of either central or upwind convective derivatives. It is a true benchmark rod-bundle code withoutmore » invoking any assumptions in the case of laminar flow. However, for turbulent flow, some empiricism must be employed due to the closure problem of turbulence modeling. The detailed velocity and temperature distributions calculated from the code can be used to benchmark and calibrate empirical coefficients employed in subchannel codes and porous-medium analyses.« less

Tubing and cable cutting tool

NASA Technical Reports Server (NTRS)

Mcsmith, D. D.; Richardson, J. I. (Inventor)

1984-01-01

A hand held hydraulic cutting tool was developed which is particularly useful in deactivating ejection seats in military aircraft rescue operations. The tool consists primarily of a hydraulic system composed of a fluid reservoir, a pumping piston, and an actuator piston. Mechanical cutting jaws are attached to the actuator piston rod. The hydraulic system is controlled by a pump handle. As the pump handle is operated the actuator piston rod is forced outward and thus the cutting jaws are forced together. The frame of the device is a flexible metal tubing which permits easy positioning of the tool cutting jaws in remote and normally inaccessible locations. Bifurcated cutting edges ensure removal of a section of the tubing or cable to thereby reduce the possibility of accidental reactivation of the tubing or cable being severed.

An improved equivalent circuit model of a four rod deflecting cavity

NASA Astrophysics Data System (ADS)

Apsimon, R.; Burt, G.

2017-03-01

In this paper we present an improved equivalent circuit model for a four rod deflecting cavity which calculates the frequencies of the first four modes of the cavity as well as the RT/Q for the deflecting mode. Equivalent circuit models of RF cavities give intuition and understanding about how the cavity operates and what changes can be made to modify the frequency, without the need for RF simulations, which can be time-consuming. We parameterise a generic four rod deflecting cavity into a geometry consisting of simple shapes. Equations are derived for the line impedance of the rods and the capacitance between the rods and these are used to calculate the resonant frequency of the deflecting dipole mode as well as the lower order mode and the model is bench-marked against two test cases; the CEBAF separator and the HL-LHC 4-rod LHC crab cavity. CST and the equivalent circuit model agree within 4% for both cavities with the LOM frequency and within 1% for the deflecting frequency. RT/Q differs between the model and CST by 37% for the CEBAF separator and 25% for the HL-LHC 4-rod crab cavity; however this is sufficient for understanding how to optimise the cavity design. The model has then been utilised to suggest a method of separating the modal frequencies in the HL-LHC crab cavity and to suggest design methodologies to optimise the cavity geometries.

Force-moment line element method for flexible slender bodies in Stokes flow.

PubMed

Jiang, H; Yang, B

2013-09-01

The hydrodynamics of flexible slender bodies in Stokes flow is studied by taking into account the fluid-structure interaction through both forces and coupled moments. The fluid subjected to line sources of forces and moments is described by using integral equations. Meanwhile, the flexible slender body is modeled using finite beam elements. The two sides are linked through interfacial continuity conditions. Upon discretization, it results in a higher-order line element method for efficient and accurate solution of slender-body hydrodynamics. Four examples are presented to demonstrate the validity and efficiency of the present method: (a) hydrodynamics of a flexible slender rod subjected to a torque at one end, (b) hydrodynamics of a flexible slender rod subjected to a bending moment at one end, (c) hydrodynamics of a flexible slender rod subjected to a cyclic force, and (d) hydrodynamics of a flexible slender rod with a magnetized head within a rotating magnetic field. Examples (a) and (b) may serve as benchmark solutions and examples (c) and (d) show how planar and spiral waves can be excited in a slender body.

PML solution of longitudinal wave propagation in heterogeneous media

NASA Astrophysics Data System (ADS)

Farzanian, M.; Arbabi, Freydoon; Pak, Ronald

2016-06-01

This paper describes the development of a model for unbounded heterogeneous domains with radiation damping produced by an unphysical wave absorbing layer. The Perfectly Matched Layer (PML) approach is used along with a displacement-based finite element. The heterogeneous model is validated using the closed-form solution of a benchmark problem: a free rod with two-part modulus subjected to a specified time history. Both elastically supported and unsupported semi-infinite rods with different degrees of inhomogeneity and loading are considered. Numerical results illustrate the effects of inhomogeneity on the response and are compared with those for equivalent homogeneous domains. The effects of characteristic features of the inhomogeneous problem, presence of local maxima and cut-off frequency are determined. A degenerate case of a homogeneous semi-infinite rod on elastic foundations is produced by tending the magnitude of the foundation stiffness to zero. The response of the latter is compared with that of a free rod. The importance of proper selection of the PML parameters to highly accurate and efficient results is demonstrated by example problems.

Evaluation of Neutron Radiography Reactor LEU-Core Start-Up Measurements

DOE PAGES

Bess, John D.; Maddock, Thomas L.; Smolinski, Andrew T.; ...

2014-11-04

Benchmark models were developed to evaluate the cold-critical start-up measurements performed during the fresh core reload of the Neutron Radiography (NRAD) reactor with Low Enriched Uranium (LEU) fuel. Experiments include criticality, control-rod worth measurements, shutdown margin, and excess reactivity for four core loadings with 56, 60, 62, and 64 fuel elements. The worth of four graphite reflector block assemblies and an empty dry tube used for experiment irradiations were also measured and evaluated for the 60-fuel-element core configuration. Dominant uncertainties in the experimental k eff come from uncertainties in the manganese content and impurities in the stainless steel fuel claddingmore » as well as the 236U and erbium poison content in the fuel matrix. Calculations with MCNP5 and ENDF/B-VII.0 neutron nuclear data are approximately 1.4% (9σ) greater than the benchmark model eigenvalues, which is commonly seen in Monte Carlo simulations of other TRIGA reactors. Simulations of the worth measurements are within the 2σ uncertainty for most of the benchmark experiment worth values. The complete benchmark evaluation details are available in the 2014 edition of the International Handbook of Evaluated Reactor Physics Benchmark Experiments.« less

Evaluation of Neutron Radiography Reactor LEU-Core Start-Up Measurements

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

Bess, John D.; Maddock, Thomas L.; Smolinski, Andrew T.

Benchmark models were developed to evaluate the cold-critical start-up measurements performed during the fresh core reload of the Neutron Radiography (NRAD) reactor with Low Enriched Uranium (LEU) fuel. Experiments include criticality, control-rod worth measurements, shutdown margin, and excess reactivity for four core loadings with 56, 60, 62, and 64 fuel elements. The worth of four graphite reflector block assemblies and an empty dry tube used for experiment irradiations were also measured and evaluated for the 60-fuel-element core configuration. Dominant uncertainties in the experimental k eff come from uncertainties in the manganese content and impurities in the stainless steel fuel claddingmore » as well as the 236U and erbium poison content in the fuel matrix. Calculations with MCNP5 and ENDF/B-VII.0 neutron nuclear data are approximately 1.4% (9σ) greater than the benchmark model eigenvalues, which is commonly seen in Monte Carlo simulations of other TRIGA reactors. Simulations of the worth measurements are within the 2σ uncertainty for most of the benchmark experiment worth values. The complete benchmark evaluation details are available in the 2014 edition of the International Handbook of Evaluated Reactor Physics Benchmark Experiments.« less

The surface elevation table: marker horizon method for measuring wetland accretion and elevation dynamics

USGS Publications Warehouse

Callaway, John C.; Cahoon, Donald R.; Lynch, James C.

2014-01-01

Tidal wetlands are highly sensitive to processes that affect their elevation relative to sea level. The surface elevation table–marker horizon (SET–MH) method has been used to successfully measure these processes, including sediment accretion, changes in relative elevation, and shallow soil processes (subsidence and expansion due to root production). The SET–MH method is capable of measuring changes at very high resolution (±millimeters) and has been used worldwide both in natural wetlands and under experimental conditions. Marker horizons are typically deployed using feldspar over 50- by 50-cm plots, with replicate plots at each sampling location. Plots are sampled using a liquid N2 cryocorer that freezes a small sample, allowing the handling and measurement of soft and easily compressed soils with minimal compaction. The SET instrument is a portable device that is attached to a permanent benchmark to make high-precision measurements of wetland surface elevation. The SET instrument has evolved substantially in recent decades, and the current rod SET (RSET) is widely used. For the RSET, a 15-mm-diameter stainless steel rod is pounded into the ground until substantial resistance is achieved to establish a benchmark. The SET instrument is attached to the benchmark and leveled such that it reoccupies the same reference plane in space, and pins lowered from the instrument repeatedly measure the same point on the soil surface. Changes in the height of the lowered pins reflect changes in the soil surface. Permanent or temporary platforms provide access to SET and MH locations without disturbing the wetland surface.

MC21 analysis of the MIT PWR benchmark: Hot zero power results

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

Kelly Iii, D. J.; Aviles, B. N.; Herman, B. R.

2013-07-01

MC21 Monte Carlo results have been compared with hot zero power measurements from an operating pressurized water reactor (PWR), as specified in a new full core PWR performance benchmark from the MIT Computational Reactor Physics Group. Included in the comparisons are axially integrated full core detector measurements, axial detector profiles, control rod bank worths, and temperature coefficients. Power depressions from grid spacers are seen clearly in the MC21 results. Application of Coarse Mesh Finite Difference (CMFD) acceleration within MC21 has been accomplished, resulting in a significant reduction of inactive batches necessary to converge the fission source. CMFD acceleration has alsomore » been shown to work seamlessly with the Uniform Fission Site (UFS) variance reduction method. (authors)« less

TGfU--Would You Know It if You Saw It? Benchmarks from the Tacit Knowledge of the Founders

ERIC Educational Resources Information Center

Butler, Joy

2014-01-01

This paper explores the tacit expert knowledge and understanding about games curriculum and pedagogy of three men, Len Almond, David Bunker, and Rod Thorpe, credited as the founders of the Teaching Games for Understanding (TGfU) model. The model emerged from teacher practice in the late 1970s and was little theorized at the time, apart from a…

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

Wang, Jy-An John; Wang, Hong; Jiang, Hao

The objective of this project is to perform a systematic study of SNF/UNF (spent nuclear fuel/or used nuclear fuel) integrity under simulated transportation environments by using hot cell testing technology developed recently at Oak Ridge National Laboratory (ORNL), CIRFT (Cyclic Integrated Reversible-Bending Fatigue Tester). Under Nuclear Regulatory Commission (NRC) sponsorship, ORNL completed four benchmarking tests, four static tests, and twelve dynamic or cycle tests on H. B. Robinson (HBR) high burn-up (HBU) fuel. With support from the US Department of Energy and the NRC, CIRFT testing has been continued. The CIRFT testing was conducted on three HBR rods (R3, R4,more » and R5), with two specimens failed and one specimen un-failed. The total number of cycles in the test of un-failed specimens went over 2.23 107; the test was stopped as because the specimen did not show any sign of failure. The data analysis on all the HBR SNF rods demonstrated that it is necessary to characterize the fatigue life of used fuel rods in terms of both the curvature amplitude and the maximum of absolute of curvature extremes. The latter is significant because the maxima of extremes signify the maximum of tensile stress of the outer fiber of the bending rod. So far, a large variety of hydrogen contents has been covered in the CIRFT testing on HBR rods. It has been shown that the load amplitude is the dominant factor that controls the lifetime of bending rods, but the hydrogen content also has an important effect on the lifetime attained, according to the load range tested.« less

Surface roughness effects on turbulent Couette flow

NASA Astrophysics Data System (ADS)

Lee, Young Mo; Lee, Jae Hwa

2017-11-01

Direct numerical simulation of a turbulent Couette flow with two-dimensional (2-D) rod roughness is performed to examine the effects of the surface roughness. The Reynolds number based on the channel centerline laminar velocity (Uco) and channel half height (h) is Re =7200. The 2-D rods are periodically arranged with a streamwise pitch of λ = 8 k on the bottom wall, and the roughness height is k = 0.12 h. It is shown that the wall-normal extent for the logarithmic layer is significantly shortened in the rough-wall turbulent Couette flow, compared to a turbulent Couette flow with smooth wall. Although the Reynolds stresses are increased in a turbulent channel flow with surface roughness in the outer layer due to large-scale ejection motions produced by the 2-D rods, those of the rough-wall Couette flow are decreased. Isosurfaces of the u-structures averaged in time suggest that the decrease of the turbulent activity near the centerline is associated with weakened large-scale counter-rotating roll modes by the surface roughness. This research was supported by the National Research Foundation of Korea (NRF) funded by the Ministry of Education (NRF-2017R1D1A1A09000537) and the Ministry of Science, ICT & Future Planning (NRF-2017R1A5A1015311).

Benchmark Evaluation of Fuel Effect and Material Worth Measurements for a Beryllium-Reflected Space Reactor Mockup

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

Marshall, Margaret A.; Bess, John D.

2015-02-01

The critical configuration of the small, compact critical assembly (SCCA) experiments performed at the Oak Ridge Critical Experiments Facility (ORCEF) in 1962-1965 have been evaluated as acceptable benchmark experiments for inclusion in the International Handbook of Evaluated Criticality Safety Benchmark Experiments. The initial intent of these experiments was to support the design of the Medium Power Reactor Experiment (MPRE) program, whose purpose was to study “power plants for the production of electrical power in space vehicles.” The third configuration in this series of experiments was a beryllium-reflected assembly of stainless-steel-clad, highly enriched uranium (HEU)-O 2 fuel mockup of a potassium-cooledmore » space power reactor. Reactivity measurements cadmium ratio spectral measurements and fission rate measurements were measured through the core and top reflector. Fuel effect worth measurements and neutron moderating and absorbing material worths were also measured in the assembly fuel region. The cadmium ratios, fission rate, and worth measurements were evaluated for inclusion in the International Handbook of Evaluated Criticality Safety Benchmark Experiments. The fuel tube effect and neutron moderating and absorbing material worth measurements are the focus of this paper. Additionally, a measurement of the worth of potassium filling the core region was performed but has not yet been evaluated Pellets of 93.15 wt.% enriched uranium dioxide (UO 2) were stacked in 30.48 cm tall stainless steel fuel tubes (0.3 cm tall end caps). Each fuel tube had 26 pellets with a total mass of 295.8 g UO 2 per tube. 253 tubes were arranged in 1.506-cm triangular lattice. An additional 7-tube cluster critical configuration was also measured but not used for any physics measurements. The core was surrounded on all side by a beryllium reflector. The fuel effect worths were measured by removing fuel tubes at various radius. An accident scenario was also simulated by moving outward twenty fuel rods from the periphery of the core so they were touching the core tank. The change in the system reactivity when the fuel tube(s) were removed/moved compared with the base configuration was the worth of the fuel tubes or accident scenario. The worth of neutron absorbing and moderating materials was measured by inserting material rods into the core at regular intervals or placing lids at the top of the core tank. Stainless steel 347, tungsten, niobium, polyethylene, graphite, boron carbide, aluminum and cadmium rods and/or lid worths were all measured. The change in the system reactivity when a material was inserted into the core is the worth of the material.« less

Reactivity Initiated Accident Simulation to Inform Transient Testing of Candidate Advanced Cladding

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

Brown, Nicholas R; Wysocki, Aaron J; Terrani, Kurt A

2016-01-01

Abstract. Advanced cladding materials with potentially enhanced accident tolerance will yield different light water reactor performance and safety characteristics than the present zirconium-based cladding alloys. These differences are due to different cladding material properties and responses to the transient, and to some extent, reactor physics, thermal, and hydraulic characteristics. Some of the differences in reactors physics characteristics will be driven by the fundamental properties (e.g., absorption in iron for an iron-based cladding) and others will be driven by design modifications necessitated by the candidate cladding materials (e.g., a larger fuel pellet to compensate for parasitic absorption). Potential changes in thermalmore » hydraulic limits after transition from the current zirconium-based cladding to the advanced materials will also affect the transient response of the integral fuel. This paper leverages three-dimensional reactor core simulation capabilities to inform on appropriate experimental test conditions for candidate advanced cladding materials in a control rod ejection event. These test conditions are using three-dimensional nodal kinetics simulations of a reactivity initiated accident (RIA) in a representative state-of-the-art pressurized water reactor with both nuclear-grade iron-chromium-aluminum (FeCrAl) and silicon carbide based (SiC-SiC) cladding materials. The effort yields boundary conditions for experimental mechanical tests, specifically peak cladding strain during the power pulse following the rod ejection. The impact of candidate cladding materials on the reactor kinetics behavior of RIA progression versus reference zirconium cladding is predominantly due to differences in: (1) fuel mass/volume/specific power density, (2) spectral effects due to parasitic neutron absorption, (3) control rod worth due to hardened (or softened) spectrum, and (4) initial conditions due to power peaking and neutron transport cross sections in the equilibrium cycle cores due to hardened (or softened) spectrum. This study shows minimal impact of SiC-based cladding configurations on the transient response versus reference zirconium-based cladding. However, the FeCrAl cladding response indicates similar energy deposition, but with significantly shorter pulses of higher magnitude. Therefore the FeCrAl-based cases have a more rapid fuel thermal expansion rate and the resultant pellet-cladding interaction occurs more rapidly.« less

Benchmark of Atucha-2 PHWR RELAP5-3D control rod model by Monte Carlo MCNP5 core calculation

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

Pecchia, M.; D'Auria, F.; Mazzantini, O.

2012-07-01

Atucha-2 is a Siemens-designed PHWR reactor under construction in the Republic of Argentina. Its geometrical complexity and peculiarities require the adoption of advanced Monte Carlo codes for performing realistic neutronic simulations. Therefore core models of Atucha-2 PHWR were developed using MCNP5. In this work a methodology was set up to collect the flux in the hexagonal mesh by which the Atucha-2 core is represented. The scope of this activity is to evaluate the effect of obliquely inserted control rod on neutron flux in order to validate the RELAP5-3D{sup C}/NESTLE three dimensional neutron kinetic coupled thermal-hydraulic model, applied by GRNSPG/UNIPI formore » performing selected transients of Chapter 15 FSAR of Atucha-2. (authors)« less

Development and verification of NRC`s single-rod fuel performance codes FRAPCON-3 AND FRAPTRAN

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

Beyer, C.E.; Cunningham, M.E.; Lanning, D.D.

1998-03-01

The FRAPCON and FRAP-T code series, developed in the 1970s and early 1980s, are used by the US Nuclear Regulatory Commission (NRC) to predict fuel performance during steady-state and transient power conditions, respectively. Both code series are now being updated by Pacific Northwest National Laboratory to improve their predictive capabilities at high burnup levels. The newest versions of the codes are called FRAPCON-3 and FRAPTRAN. The updates to fuel property and behavior models are focusing on providing best estimate predictions under steady-state and fast transient power conditions up to extended fuel burnups (> 55 GWd/MTU). Both codes will be assessedmore » against a data base independent of the data base used for code benchmarking and an estimate of code predictive uncertainties will be made based on comparisons to the benchmark and independent data bases.« less

Probabilistic analysis on the failure of reactivity control for the PWR

NASA Astrophysics Data System (ADS)

Sony Tjahyani, D. T.; Deswandri; Sunaryo, G. R.

2018-02-01

The fundamental safety function of the power reactor is to control reactivity, to remove heat from the reactor, and to confine radioactive material. The safety analysis is used to ensure that each parameter is fulfilled during the design and is done by deterministic and probabilistic method. The analysis of reactivity control is important to be done because it will affect the other of fundamental safety functions. The purpose of this research is to determine the failure probability of the reactivity control and its failure contribution on a PWR design. The analysis is carried out by determining intermediate events, which cause the failure of reactivity control. Furthermore, the basic event is determined by deductive method using the fault tree analysis. The AP1000 is used as the object of research. The probability data of component failure or human error, which is used in the analysis, is collected from IAEA, Westinghouse, NRC and other published documents. The results show that there are six intermediate events, which can cause the failure of the reactivity control. These intermediate events are uncontrolled rod bank withdrawal at low power or full power, malfunction of boron dilution, misalignment of control rod withdrawal, malfunction of improper position of fuel assembly and ejection of control rod. The failure probability of reactivity control is 1.49E-03 per year. The causes of failures which are affected by human factor are boron dilution, misalignment of control rod withdrawal and malfunction of improper position for fuel assembly. Based on the assessment, it is concluded that the failure probability of reactivity control on the PWR is still within the IAEA criteria.

Deterministic Modeling of the High Temperature Test Reactor

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

Ortensi, J.; Cogliati, J. J.; Pope, M. A.

2010-06-01

Idaho National Laboratory (INL) is tasked with the development of reactor physics analysis capability of the Next Generation Nuclear Power (NGNP) project. In order to examine INL’s current prismatic reactor deterministic analysis tools, the project is conducting a benchmark exercise based on modeling the High Temperature Test Reactor (HTTR). This exercise entails the development of a model for the initial criticality, a 19 column thin annular core, and the fully loaded core critical condition with 30 columns. Special emphasis is devoted to the annular core modeling, which shares more characteristics with the NGNP base design. The DRAGON code is usedmore » in this study because it offers significant ease and versatility in modeling prismatic designs. Despite some geometric limitations, the code performs quite well compared to other lattice physics codes. DRAGON can generate transport solutions via collision probability (CP), method of characteristics (MOC), and discrete ordinates (Sn). A fine group cross section library based on the SHEM 281 energy structure is used in the DRAGON calculations. HEXPEDITE is the hexagonal z full core solver used in this study and is based on the Green’s Function solution of the transverse integrated equations. In addition, two Monte Carlo (MC) based codes, MCNP5 and PSG2/SERPENT, provide benchmarking capability for the DRAGON and the nodal diffusion solver codes. The results from this study show a consistent bias of 2–3% for the core multiplication factor. This systematic error has also been observed in other HTTR benchmark efforts and is well documented in the literature. The ENDF/B VII graphite and U235 cross sections appear to be the main source of the error. The isothermal temperature coefficients calculated with the fully loaded core configuration agree well with other benchmark participants but are 40% higher than the experimental values. This discrepancy with the measurement stems from the fact that during the experiments the control rods were adjusted to maintain criticality, whereas in the model, the rod positions were fixed. In addition, this work includes a brief study of a cross section generation approach that seeks to decouple the domain in order to account for neighbor effects. This spectral interpenetration is a dominant effect in annular HTR physics. This analysis methodology should be further explored in order to reduce the error that is systematically propagated in the traditional generation of cross sections.« less

Results of the first order leveling surveys in the Mexicali Valley and at the Cerro Prieto field

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

de la Pena L, A.

1981-01-01

The results obtained from the third leveling survey carried out by the Direccion General de Geografia del Territorio Nacional (previously DETENAL) during November and December 1979 are presented. Calculations of the changes in field elevation and plots showing comparisons of the 1977, 1978, and 1979 surveys are also presented. Results from a second order leveling survey performed to ascertain the extent of ground motion resulting from the 8 June 1980 earthquake are presented. This magnitude ML = 6.7 earthquake with epicenter located 15 km southeast of the Guadalupe Victoria village, caused fissures on the surface, the formation of small sandmore » volcanos, and the ejection of ground water in the vicinity of the Cerro Prieto field. This leveling survey was carried out between benchmark BN-10067 at the intersection of the Solfatara canal and the Sonora-Baja California railroad, and benchmark BN-10055 located at the Delta station.« less

Experimental results from the VENUS-F critical reference state for the GUINEVERE accelerator driven system project

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

Uyttenhove, W.; Baeten, P.; Ban, G.

The GUINEVERE (Generation of Uninterrupted Intense Neutron pulses at the lead Venus Reactor) project was launched in 2006 within the framework of FP6 EUROTRANS in order to validate on-line reactivity monitoring and subcriticality level determination in Accelerator Driven Systems. Therefore the VENUS reactor at SCK.CEN in Mol (Belgium) was modified towards a fast core (VENUS-F) and coupled to the GENEPI-3C accelerator built by CNRS The accelerator can operate in both continuous and pulsed mode. The VENUS-F core is loaded with enriched Uranium and reflected with solid lead. A well-chosen critical reference state is indispensable for the validation of the on-linemore » subcriticality monitoring methodology. Moreover a benchmarking tool is required for nuclear data research and code validation. In this paper the design and the importance of the critical reference state for the GUINEVERE project are motivated. The results of the first experimental phase on the critical core are presented. The control rods worth is determined by the rod drop technique and the application of the Modified Source Multiplication (MSM) method allows the determination of the worth of the safety rods. The results are implemented in the VENUS-F core certificate for full exploitation of the critical core. (authors)« less

ZPR-6 assembly 7 high {sup 240} PU core : a cylindrical assemby with mixed (PU, U)-oxide fuel and a central high {sup 240} PU zone.

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

Lell, R. M.; Schaefer, R. W.; McKnight, R. D.

Over a period of 30 years more than a hundred Zero Power Reactor (ZPR) critical assemblies were constructed at Argonne National Laboratory. The ZPR facilities, ZPR-3, ZPR-6, ZPR-9 and ZPPR, were all fast critical assembly facilities. The ZPR critical assemblies were constructed to support fast reactor development, but data from some of these assemblies are also well suited to form the basis for criticality safety benchmarks. Of the three classes of ZPR assemblies, engineering mockups, engineering benchmarks and physics benchmarks, the last group tends to be most useful for criticality safety. Because physics benchmarks were designed to test fast reactormore » physics data and methods, they were as simple as possible in geometry and composition. The principal fissile species was {sup 235}U or {sup 239}Pu. Fuel enrichments ranged from 9% to 95%. Often there were only one or two main core diluent materials, such as aluminum, graphite, iron, sodium or stainless steel. The cores were reflected (and insulated from room return effects) by one or two layers of materials such as depleted uranium, lead or stainless steel. Despite their more complex nature, a small number of assemblies from the other two classes would make useful criticality safety benchmarks because they have features related to criticality safety issues, such as reflection by soil-like material. The term 'benchmark' in a ZPR program connotes a particularly simple loading aimed at gaining basic reactor physics insight, as opposed to studying a reactor design. In fact, the ZPR-6/7 Benchmark Assembly (Reference 1) had a very simple core unit cell assembled from plates of depleted uranium, sodium, iron oxide, U3O8, and plutonium. The ZPR-6/7 core cell-average composition is typical of the interior region of liquid-metal fast breeder reactors (LMFBRs) of the era. It was one part of the Demonstration Reactor Benchmark Program,a which provided integral experiments characterizing the important features of demonstration-size LMFBRs. As a benchmark, ZPR-6/7 was devoid of many 'real' reactor features, such as simulated control rods and multiple enrichment zones, in its reference form. Those kinds of features were investigated experimentally in variants of the reference ZPR-6/7 or in other critical assemblies in the Demonstration Reactor Benchmark Program.« less

The impact of interface bonding efficiency on high-burnup spent nuclear fuel dynamic performance

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

Jiang, Hao; Wang, Jy-An John; Wang, Hong

Finite element analysis (FEA) was used to investigate the impact of interfacial bonding efficiency at pellet-pellet and pellet-clad interfaces of high-burnup (HBU) spent nuclear fuel (SNF) on system dynamic performance. Bending moments M were applied to FEA model to evaluate the system responses. From bending curvature, κ, flexural rigidity EI can be estimated as EI = M/κ. The FEA simulation results were benchmarked with experimental results from cyclic integrated reversal bending fatigue test (CIRFT) of HBR fuel rods. The consequence of interface debonding between fuel pellets and cladding is a redistribution of the loads carried by the fuel pellets tomore » the clad, which results in a reduction in composite rod system flexural rigidity. Furthermore, the interface bonding efficiency at the pellet-pellet and pellet-clad interfaces can significantly dictate the SNF system dynamic performance. With the consideration of interface bonding efficiency, the HBU SNF fuel property was estimated with CIRFT test data.« less

The impact of interface bonding efficiency on high-burnup spent nuclear fuel dynamic performance

DOE PAGES

Jiang, Hao; Wang, Jy-An John; Wang, Hong

2016-09-26

Finite element analysis (FEA) was used to investigate the impact of interfacial bonding efficiency at pellet-pellet and pellet-clad interfaces of high-burnup (HBU) spent nuclear fuel (SNF) on system dynamic performance. Bending moments M were applied to FEA model to evaluate the system responses. From bending curvature, κ, flexural rigidity EI can be estimated as EI = M/κ. The FEA simulation results were benchmarked with experimental results from cyclic integrated reversal bending fatigue test (CIRFT) of HBR fuel rods. The consequence of interface debonding between fuel pellets and cladding is a redistribution of the loads carried by the fuel pellets tomore » the clad, which results in a reduction in composite rod system flexural rigidity. Furthermore, the interface bonding efficiency at the pellet-pellet and pellet-clad interfaces can significantly dictate the SNF system dynamic performance. With the consideration of interface bonding efficiency, the HBU SNF fuel property was estimated with CIRFT test data.« less

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

Jin, C.; Potts, I.; Reeks, M. W., E-mail: mike.reeks@ncl.ac.uk

We present a simple stochastic quadrant model for calculating the transport and deposition of heavy particles in a fully developed turbulent boundary layer based on the statistics of wall-normal fluid velocity fluctuations obtained from a fully developed channel flow. Individual particles are tracked through the boundary layer via their interactions with a succession of random eddies found in each of the quadrants of the fluid Reynolds shear stress domain in a homogeneous Markov chain process. In this way, we are able to account directly for the influence of ejection and sweeping events as others have done but without resorting tomore » the use of adjustable parameters. Deposition rate predictions for a wide range of heavy particles predicted by the model compare well with benchmark experimental measurements. In addition, deposition rates are compared with those obtained from continuous random walk models and Langevin equation based ejection and sweep models which noticeably give significantly lower deposition rates. Various statistics related to the particle near wall behavior are also presented. Finally, we consider the model limitations in using the model to calculate deposition in more complex flows where the near wall turbulence may be significantly different.« less

Prediction of the Reactor Antineutrino Flux for the Double Chooz Experiment

NASA Astrophysics Data System (ADS)

Jones, Chirstopher LaDon

This thesis benchmarks the deterministic lattice code, DRAGON, against data, and then applies this code to make a prediction for the antineutrino flux from the Chooz Bl and B2 reactors. Data from the destructive assay of rods from the Takahama-3 reactor and from the SONGS antineutrino detector are used for comparisons. The resulting prediction from the tuned DRAGON code is then compared to the first antineutrino event spectra from Double Chooz. Use of this simulation in nuclear nonproliferation studies is discussed. (Copies available exclusively from MIT Libraries, libraries.mit.edu/docs - docs@mit.edu)

Deterministic Modeling of the High Temperature Test Reactor with DRAGON-HEXPEDITE

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

J. Ortensi; M.A. Pope; R.M. Ferrer

2010-10-01

The Idaho National Laboratory (INL) is tasked with the development of reactor physics analysis capability of the Next Generation Nuclear Power (NGNP) project. In order to examine the INL’s current prismatic reactor analysis tools, the project is conducting a benchmark exercise based on modeling the High Temperature Test Reactor (HTTR). This exercise entails the development of a model for the initial criticality, a 19 fuel column thin annular core, and the fully loaded core critical condition with 30 fuel columns. Special emphasis is devoted to physical phenomena and artifacts in HTTR that are similar to phenomena and artifacts in themore » NGNP base design. The DRAGON code is used in this study since it offers significant ease and versatility in modeling prismatic designs. DRAGON can generate transport solutions via Collision Probability (CP), Method of Characteristics (MOC) and Discrete Ordinates (Sn). A fine group cross-section library based on the SHEM 281 energy structure is used in the DRAGON calculations. The results from this study show reasonable agreement in the calculation of the core multiplication factor with the MC methods, but a consistent bias of 2–3% with the experimental values is obtained. This systematic error has also been observed in other HTTR benchmark efforts and is well documented in the literature. The ENDF/B VII graphite and U235 cross sections appear to be the main source of the error. The isothermal temperature coefficients calculated with the fully loaded core configuration agree well with other benchmark participants but are 40% higher than the experimental values. This discrepancy with the measurement partially stems from the fact that during the experiments the control rods were adjusted to maintain criticality, whereas in the model, the rod positions were fixed. In addition, this work includes a brief study of a cross section generation approach that seeks to decouple the domain in order to account for neighbor effects. This spectral interpenetration is a dominant effect in annular HTR physics. This analysis methodology should be further explored in order to reduce the error that is systematically propagated in the traditional generation of cross sections.« less

Between a Map and a Data Rod

NASA Technical Reports Server (NTRS)

Teng, William; Rui, Hualan; Strub, Richard; Vollmer, Bruce

2015-01-01

A Digital Divide has long stood between how NASA and other satellite-derived data are typically archived (time-step arrays or maps) and how hydrology and other point-time series oriented communities prefer to access those data. In essence, the desired method of data access is orthogonal to the way the data are archived. Our approach to bridging the Divide is part of a larger NASA-supported data rods project to enhance access to and use of NASA and other data by the Consortium of Universities for the Advancement of Hydrologic Science, Inc. (CUAHSI) Hydrologic Information System (HIS) and the larger hydrology community. Our main objective was to determine a way to reorganize data that is optimal for these communities. Two related objectives were to optimally reorganize data in a way that (1) is operational and fits in and leverages the existing Goddard Earth Sciences Data and Information Services Center (GES DISC) operational environment and (2) addresses the scaling up of data sets available as time series from those archived at the GES DISC to potentially include those from other Earth Observing System Data and Information System (EOSDIS) data archives. Through several prototype efforts and lessons learned, we arrived at a non-database solution that satisfied our objectivesconstraints. We describe, in this presentation, how we implemented the operational production of pre-generated data rods and, considering the tradeoffs between length of time series (or number of time steps), resources needed, and performance, how we implemented the operational production of on-the-fly (virtual) data rods. For the virtual data rods, we leveraged a number of existing resources, including the NASA Giovanni Cache and NetCDF Operators (NCO) and used data cubes processed in parallel. Our current benchmark performance for virtual generation of data rods is about a years worth of time series for hourly data (9,000 time steps) in 90 seconds. Our approach is a specific implementation of the general optimal strategy of reorganizing data to match the desired means of access. Results from our project have already significantly extended NASA data to the large and important hydrology user community that has been, heretofore, mostly unable to easily access and use NASA data.

Between a Map and a Data Rod

NASA Astrophysics Data System (ADS)

Teng, W. L.; Rui, H.; Strub, R. F.; Vollmer, B.

2015-12-01

A "Digital Divide" has long stood between how NASA and other satellite-derived data are typically archived (time-step arrays or "maps") and how hydrology and other point-time series oriented communities prefer to access those data. In essence, the desired method of data access is orthogonal to the way the data are archived. Our approach to bridging the Divide is part of a larger NASA-supported "data rods" project to enhance access to and use of NASA and other data by the Consortium of Universities for the Advancement of Hydrologic Science, Inc. (CUAHSI) Hydrologic Information System (HIS) and the larger hydrology community. Our main objective was to determine a way to reorganize data that is optimal for these communities. Two related objectives were to optimally reorganize data in a way that (1) is operational and fits in and leverages the existing Goddard Earth Sciences Data and Information Services Center (GES DISC) operational environment and (2) addresses the scaling up of data sets available as time series from those archived at the GES DISC to potentially include those from other Earth Observing System Data and Information System (EOSDIS) data archives. Through several prototype efforts and lessons learned, we arrived at a non-database solution that satisfied our objectives/constraints. We describe, in this presentation, how we implemented the operational production of pre-generated data rods and, considering the tradeoffs between length of time series (or number of time steps), resources needed, and performance, how we implemented the operational production of on-the-fly ("virtual") data rods. For the virtual data rods, we leveraged a number of existing resources, including the NASA Giovanni Cache and NetCDF Operators (NCO) and used data cubes processed in parallel. Our current benchmark performance for virtual generation of data rods is about a year's worth of time series for hourly data (~9,000 time steps) in ~90 seconds. Our approach is a specific implementation of the general optimal strategy of reorganizing data to match the desired means of access. Results from our project have already significantly extended NASA data to the large and important hydrology user community that has been, heretofore, mostly unable to easily access and use NASA data.

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

Gauld, Ian C.; Giaquinto, J. M.; Delashmitt, J. S.

Destructive radiochemical assay measurements of spent nuclear fuel rod segments from an assembly irradiated in the Three Mile Island unit 1 (TMI-1) pressurized water reactor have been performed at Oak Ridge National Laboratory (ORNL). Assay data are reported for five samples from two fuel rods of the same assembly. The TMI-1 assembly was a 15 X 15 design with an initial enrichment of 4.013 wt% 235U, and the measured samples achieved burnups between 45.5 and 54.5 gigawatt days per metric ton of initial uranium (GWd/t). Measurements were performed mainly using inductively coupled plasma mass spectrometry after elemental separation via highmore » performance liquid chromatography. High precision measurements were achieved using isotope dilution techniques for many of the lanthanides, uranium, and plutonium isotopes. Measurements are reported for more than 50 different isotopes and 16 elements. One of the two TMI-1 fuel rods measured in this work had been measured previously by Argonne National Laboratory (ANL), and these data have been widely used to support code and nuclear data validation. Recently, ORNL provided an important opportunity to independently cross check results against previous measurements performed at ANL. The measured nuclide concentrations are used to validate burnup calculations using the SCALE nuclear systems modeling and simulation code suite. These results show that the new measurements provide reliable benchmark data for computer code validation.« less

A class of ejecta transport test problems

NASA Astrophysics Data System (ADS)

Oro, David M.; Hammerberg, J. E.; Buttler, William T.; Mariam, Fesseha G.; Morris, Christopher L.; Rousculp, Chris; Stone, Joseph B.

2012-03-01

Hydro code implementations of ejecta dynamics at shocked interfaces presume a source distribution function of particulate masses and velocities, f0(m,u;t). Some properties of this source distribution function have been determined from Taylor- and supported-shockwave experiments. Such experiments measure the mass moment of f0 under vacuum conditions assuming weak particle-particle interactions and, usually, fully inelastic scattering (capture) of ejecta particles from piezoelectric diagnostic probes. Recently, planar ejection of W particles into vacuum, Ar, and Xe gas atmospheres have been carried out to provide benchmark transport data for transport model development and validation. We present those experimental results and compare them with modeled transport of the W-ejecta particles in Ar and Xe.

Re-evaluation of Spent Nuclear Fuel Assay Data for the Three Mile Island Unit 1 Reactor and Application to Code Validation

DOE PAGES

Gauld, Ian C.; Giaquinto, J. M.; Delashmitt, J. S.; ...

2016-01-01

Destructive radiochemical assay measurements of spent nuclear fuel rod segments from an assembly irradiated in the Three Mile Island unit 1 (TMI-1) pressurized water reactor have been performed at Oak Ridge National Laboratory (ORNL). Assay data are reported for five samples from two fuel rods of the same assembly. The TMI-1 assembly was a 15 X 15 design with an initial enrichment of 4.013 wt% 235U, and the measured samples achieved burnups between 45.5 and 54.5 gigawatt days per metric ton of initial uranium (GWd/t). Measurements were performed mainly using inductively coupled plasma mass spectrometry after elemental separation via highmore » performance liquid chromatography. High precision measurements were achieved using isotope dilution techniques for many of the lanthanides, uranium, and plutonium isotopes. Measurements are reported for more than 50 different isotopes and 16 elements. One of the two TMI-1 fuel rods measured in this work had been measured previously by Argonne National Laboratory (ANL), and these data have been widely used to support code and nuclear data validation. Recently, ORNL provided an important opportunity to independently cross check results against previous measurements performed at ANL. The measured nuclide concentrations are used to validate burnup calculations using the SCALE nuclear systems modeling and simulation code suite. These results show that the new measurements provide reliable benchmark data for computer code validation.« less

BISON Fuel Performance Analysis of IFA-796 Rod 3 & 4 and Investigation of the Impact of Fuel Creep

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

Wirth, Brian; Terrani, Kurt A.; Sweet, Ryan T.

In order to improve the accident tolerance of light water reactor (LWR) fuel, alternative cladding materials have been proposed to replace the currently used zirconium (Zr)-based alloys. Of these materials, there is a particular focus on iron-chromiumaluminum (FeCrAl) alloys because they exhibit slower oxidation kinetics in high-temperature steam than Zr-alloys. This should decrease the energy release due to oxidation and slow cladding consumption in the presence of high temperature steam. These alloys should also exhibit increased “coping time” in the event of an accident scenario by improving the mechanical performance at high temperatures, allowing greater flexibility to achieve core cooling.more » As a continuation of the development of these alloys, in-reactor irradiation testing of FeCrAl cladded fuel rods has started. In order to provide insight on the possible behavior of these fuel rods as they undergo irradiation in the Halden Boiling Water Reactor, engineering analysis has been performed using FeCrAl material models implemented into the BISON fuel performance code. This milestone report provides an update on the ongoing development of modeling capability to predict FeCrAl cladding fuel performance and to provide an early look at the possible behavior of planned in-reactor FeCrAl cladding experiments. In particular, this report consists of two separate analyses. The first analysis consists of fuel performance simulations of IFA-796 rod 4 and two segments of rod 3. These simulations utilize previously implemented material models for the C35M FeCrAl alloy and UO2 to provide a bounding behavior analysis corresponding to variation of the initial fuel cladding gap thickness within the fuel rod. The second analysis is an assessment of the fuel and cladding stress states after modification of the fuel creep model that is currently implemented in the BISON fuel performance code. Effects from modifying the fuel creep model were identified for the BISON simulations of the IFA-796 rod 4 experiment, but show that varying the creep model (within the range investigated here) only provide a minimal increase in the fuel radius and maximum cladding hoop stress. Continued investigation of fuel behavioral models will include benchmarking the modified fuel creep model against available experimental data, as well as an investigation of the role that fuel cracking will play in the compliance of the fuel. Correctly calculating stress evolution in the fuel is key to assessing fuel behavior up to gap closure and the subsequent deformation of the cladding due to PCMI. The inclusion of frictional contact should also be investigated to determine the axial elongation of the fuel rods for comparison with data from this experiment.« less

On accuracy of the wave finite element predictions of wavenumbers and power flow: A benchmark problem

NASA Astrophysics Data System (ADS)

Søe-Knudsen, Alf; Sorokin, Sergey

2011-06-01

This rapid communication is concerned with justification of the 'rule of thumb', which is well known to the community of users of the finite element (FE) method in dynamics, for the accuracy assessment of the wave finite element (WFE) method. An explicit formula linking the size of a window in the dispersion diagram, where the WFE method is trustworthy, with the coarseness of a FE mesh employed is derived. It is obtained by the comparison of the exact Pochhammer-Chree solution for an elastic rod having the circular cross-section with its WFE approximations. It is shown that the WFE power flow predictions are also valid within this window.

NUCLEAR REACTOR UNLOADING APPARATUS

DOEpatents

Leverett, M.C.; Howe, J.P.

1959-01-20

An unloading device is described for a heterogeneous reactor of the type wherein the fuel elements are in the form of cylindrical slugs and are disposed in horizontal coolant tubes which traverse the reactor core, coolant fluid being circulated through the tubes. The coolant tubes have at least two inwardly protruding ribs from their lower surfaces to support the slugs in spaced relationship to the inside walls of the tubes. The unloading device consists of a ribbon-like extractor member insertable into the coolant tubes in the space between the ribs and adapted to slide under the fuel slugs thereby raising them off of the ribs and forming a slideway for removing them from the reactor. The fuel slugs are ejected by being forced out of the tubes by incoming new fuel slugs or by a push rod insentable through the inlet end of the fuel tubes.

Design and Integration of an All-Magnetic Attitude Control System for FASTSAT-HSV01's Multiple Pointing Objectives

NASA Technical Reports Server (NTRS)

DeKock, Brandon; Sanders, Devon; Vanzwieten, Tannen; Capo-Lugo, Pedro

2011-01-01

The FASTSAT-HSV01 spacecraft is a microsatellite with magnetic torque rods as it sole attitude control actuator. FASTSAT s multiple payloads and mission functions require the Attitude Control System (ACS) to maintain Local Vertical Local Horizontal (LVLH)-referenced attitudes without spin-stabilization, while the pointing errors for some attitudes be significantly smaller than the previous best-demonstrated for this type of control system. The mission requires the ACS to hold multiple stable, unstable, and non-equilibrium attitudes, as well as eject a 3U CubeSat from an onboard P-POD and recover from the ensuing tumble. This paper describes the Attitude Control System, the reasons for design choices, how the ACS integrates with the rest of the spacecraft, and gives recommendations for potential future applications of the work.

Pasta nucleosynthesis: Molecular dynamics simulations of nuclear statistical equilibrium

NASA Astrophysics Data System (ADS)

Caplan, M. E.; Schneider, A. S.; Horowitz, C. J.; Berry, D. K.

2015-06-01

Background: Exotic nonspherical nuclear pasta shapes are expected in nuclear matter at just below saturation density because of competition between short-range nuclear attraction and long-range Coulomb repulsion. Purpose: We explore the impact nuclear pasta may have on nucleosynthesis during neutron star mergers when cold dense nuclear matter is ejected and decompressed. Methods: We use a hybrid CPU/GPU molecular dynamics (MD) code to perform decompression simulations of cold dense matter with 51 200 and 409 600 nucleons from 0.080 fm-3 down to 0.00125 fm-3 . Simulations are run for proton fractions YP= 0.05, 0.10, 0.20, 0.30, and 0.40 at temperatures T = 0.5, 0.75, and 1.0 MeV. The final composition of each simulation is obtained using a cluster algorithm and compared to a constant density run. Results: Size of nuclei in the final state of decompression runs are in good agreement with nuclear statistical equilibrium (NSE) models for temperatures of 1 MeV while constant density runs produce nuclei smaller than the ones obtained with NSE. Our MD simulations produces unphysical results with large rod-like nuclei in the final state of T =0.5 MeV runs. Conclusions: Our MD model is valid at higher densities than simple nuclear statistical equilibrium models and may help determine the initial temperatures and proton fractions of matter ejected in mergers.

Nonlinear finite element modeling of vibration control of plane rod-type structural members with integrated piezoelectric patches

NASA Astrophysics Data System (ADS)

Chróścielewski, Jacek; Schmidt, Rüdiger; Eremeyev, Victor A.

2018-05-01

This paper addresses modeling and finite element analysis of the transient large-amplitude vibration response of thin rod-type structures (e.g., plane curved beams, arches, ring shells) and its control by integrated piezoelectric layers. A geometrically nonlinear finite beam element for the analysis of piezolaminated structures is developed that is based on the Bernoulli hypothesis and the assumptions of small strains and finite rotations of the normal. The finite element model can be applied to static, stability, and transient analysis of smart structures consisting of a master structure and integrated piezoelectric actuator layers or patches attached to the upper and lower surfaces. Two problems are studied extensively: (i) FE analyses of a clamped semicircular ring shell that has been used as a benchmark problem for linear vibration control in several recent papers are critically reviewed and extended to account for the effects of structural nonlinearity and (ii) a smart circular arch subjected to a hydrostatic pressure load is investigated statically and dynamically in order to study the shift of bifurcation and limit points, eigenfrequencies, and eigenvectors, as well as vibration control for loading conditions which may lead to dynamic loss of stability.

Multi-point Shock and Flux Rope Analysis of Multiple Interplanetary Coronal Mass Ejections around 2010 August 1 in the Inner Heliosphere

NASA Astrophysics Data System (ADS)

Möstl, C.; Farrugia, C. J.; Kilpua, E. K. J.; Jian, L. K.; Liu, Y.; Eastwood, J. P.; Harrison, R. A.; Webb, D. F.; Temmer, M.; Odstrcil, D.; Davies, J. A.; Rollett, T.; Luhmann, J. G.; Nitta, N.; Mulligan, T.; Jensen, E. A.; Forsyth, R.; Lavraud, B.; de Koning, C. A.; Veronig, A. M.; Galvin, A. B.; Zhang, T. L.; Anderson, B. J.

2012-10-01

We present multi-point in situ observations of a complex sequence of coronal mass ejections (CMEs) which may serve as a benchmark event for numerical and empirical space weather prediction models. On 2010 August 1, instruments on various space missions, Solar Dynamics Observatory/Solar and Heliospheric Observatory/Solar-TErrestrial-RElations-Observatory (SDO/SOHO/STEREO), monitored several CMEs originating within tens of degrees from the solar disk center. We compare their imprints on four widely separated locations, spanning 120° in heliospheric longitude, with radial distances from the Sun ranging from MESSENGER (0.38 AU) to Venus Express (VEX, at 0.72 AU) to Wind, ACE, and ARTEMIS near Earth and STEREO-B close to 1 AU. Calculating shock and flux rope parameters at each location points to a non-spherical shape of the shock, and shows the global configuration of the interplanetary coronal mass ejections (ICMEs), which have interacted, but do not seem to have merged. VEX and STEREO-B observed similar magnetic flux ropes (MFRs), in contrast to structures at Wind. The geomagnetic storm was intense, reaching two minima in the Dst index (≈ - 100 nT), and was caused by the sheath region behind the shock and one of two observed MFRs. MESSENGER received a glancing blow of the ICMEs, and the events missed STEREO-A entirely. The observations demonstrate how sympathetic solar eruptions may immerse at least 1/3 of the heliosphere in the ecliptic with their distinct plasma and magnetic field signatures. We also emphasize the difficulties in linking the local views derived from single-spacecraft observations to a consistent global picture, pointing to possible alterations from the classical picture of ICMEs.

CFD modeling of turbulent mixing through vertical pressure tube type boiling water reactor fuel rod bundles with spacer-grids

NASA Astrophysics Data System (ADS)

Verma, Shashi Kant; Sinha, S. L.; Chandraker, D. K.

2018-05-01

Numerical simulation has been carried out for the study of natural mixing of a Tracer (Passive scalar) to describe the development of turbulent diffusion in an injected sub-channel and, afterwards on, cross-mixing between adjacent sub-channels. In this investigation, post benchmark evaluation of the inter-subchannel mixing was initiated to test the ability of state-of-the-art Computational Fluid Dynamics (CFD) codes to numerically predict the important turbulence parameters downstream of a ring type spacer grid in a rod-bundle. A three-dimensional Computational Fluid Dynamics (CFD) tool (STAR-CCM+) was used to model the single phase flow through a 30° segment or 1/12th of the cross segment of a 54-rod bundle with a ring shaped spacer grid. Polyhedrons were used to discretize the computational domain, along with prismatic cells near the walls, with an overall mesh count of 5.2 M cell volumes. The Reynolds Stress Models (RSM) was tested because of RSM accounts for the turbulence anisotropy, to assess their capability in predicting the velocities as well as mass fraction of potassium nitrate measured in the experiment. In this way, the line probes are located in the different position of subchannels which could be used to characterize the progress of the mixing along the flow direction, and the degree of cross-mixing assessed using the quantity of tracer arriving in the neighbouring sub-channels. The predicted dimensionless mixing scalar along the length, however, was in good agreement with the measurements downstream of spacers.

The change of radial power factor distribution due to RCCA insertion at the first cycle core of AP1000

NASA Astrophysics Data System (ADS)

Susilo, J.; Suparlina, L.; Deswandri; Sunaryo, G. R.

2018-02-01

The using of a computer program for the PWR type core neutronic design parameters analysis has been carried out in some previous studies. These studies included a computer code validation on the neutronic parameters data values resulted from measurements and benchmarking calculation. In this study, the AP1000 first cycle core radial power peaking factor validation and analysis were performed using CITATION module of the SRAC2006 computer code. The computer code has been also validated with a good result to the criticality values of VERA benchmark core. The AP1000 core power distribution calculation has been done in two-dimensional X-Y geometry through ¼ section modeling. The purpose of this research is to determine the accuracy of the SRAC2006 code, and also the safety performance of the AP1000 core first cycle operating. The core calculations were carried out with the several conditions, those are without Rod Cluster Control Assembly (RCCA), by insertion of a single RCCA (AO, M1, M2, MA, MB, MC, MD) and multiple insertion RCCA (MA + MB, MA + MB + MC, MA + MB + MC + MD, and MA + MB + MC + MD + M1). The maximum power factor of the fuel rods value in the fuel assembly assumedapproximately 1.406. The calculation results analysis showed that the 2-dimensional CITATION module of SRAC2006 code is accurate in AP1000 power distribution calculation without RCCA and with MA+MB RCCA insertion.The power peaking factor on the first operating cycle of the AP1000 core without RCCA, as well as with single and multiple RCCA are still below in the safety limit values (less then about 1.798). So in terms of thermal power generated by the fuel assembly, then it can be considered that the AP100 core at the first operating cycle is safe.

Comparison between Measured and Simulated Radiation Doses in the Matoroshka-R Spherical phantom Experiment#1 and Area Monitoring aboard International Space Station using PADLES from May - Sep. 2012

NASA Astrophysics Data System (ADS)

Nagamatsu, Aiko; Tolochek, Raisa; Shurshakov, Vyacheslav; Nikolaev, Igor; Tawara, Hiroko; Kitajo, Keiichi; Shimada, Ken

The measurement of radiation environmental parameters in space is essential to support radiation risk assessments for astronauts and establish a benchmark for space radiation models for present and future human space activities. Since Japanese Experiment Module ‘KIBO’ was attached to the International Space Station (ISS) in 2008, we have been performing continuous space radiation dosimetery using a PADLES (Passive Dosimeter for Life-Science Experiments in Space) consisting of CR-39 PNTDs (Plastic Nuclear track detectors) and TLD-MSOs (Mg2SiO4:Tb) for various space experiments onboard the ‘KIBO’ part of the ISS. The MATROSHKA-R experiments aims to verify of dose distributions in a human body during space flight. The phantom consists of tissue equivalent material covered by a poncho jacket with 32 pockets on the surface. 20 container rods with dosimeters can be struck into the spherical phantom. Its diameter is 370 mm and it is 32 kg in weight. The first experiment onboard the KIBO at Forward No.2 area (JPM1F2 Rack2) was conducted over 114 days from 21 May to 12 September 2012 (the installation schedule inside the phantom) on the way to solar cycle 24th upward curve. 16 PADLES packages were deployed into 16 poncho pockets on the surface of the spherical phantom. Another 12 PADLES packages were deployed inside 4 rods (3 packages per rod in the outer, middle and inner side). Area monitoring in the KIBO was conducted in the same period (Area PADLES series #8 from 15 May to 16 September, 2012). Absorbed doses were measured at 17 area monitoring points in the KIBO and 28 locations (16 packages in poncho pockets and 12 inside 4 rods) in the phantom. The maximum value measured with the PADLES in the poncho pockets on the surface of the spherical phantom facing the outer wall was 0.43 mGy/day and the minimum value measured with the PADLES in the poncho pockets on the surface of the spherical phantom facing the KIBO interior was 0.30 mGy/day. The maximum absorbed doses measured inside rods was 0.28 mGy/day and the minimum value was 0.19 mGy/day. This indicates doses measured from the dosimeters placed in the outer side of each rod are relatively high compared to the doses placed in the center of rod. At this time, we also would like to show the preliminary results of comparative study between measured and Simulated Radiation Doses using the Particle and Heavy Ion Transport code System (PHITS) calculations with well developed shielding model of the KIBO and numerical spherical phantom inside.

FY2012 summary of tasks completed on PROTEUS-thermal work.

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

Lee, C.H.; Smith, M.A.

2012-06-06

PROTEUS is a suite of the neutronics codes, both old and new, that can be used within the SHARP codes being developed under the NEAMS program. Discussion here is focused on updates and verification and validation activities of the SHARP neutronics code, DeCART, for application to thermal reactor analysis. As part of the development of SHARP tools, the different versions of the DeCART code created for PWR, BWR, and VHTR analysis were integrated. Verification and validation tests for the integrated version were started, and the generation of cross section libraries based on the subgroup method was revisited for the targetedmore » reactor types. The DeCART code has been reorganized in preparation for an efficient integration of the different versions for PWR, BWR, and VHTR analysis. In DeCART, the old-fashioned common blocks and header files have been replaced by advanced memory structures. However, the changing of variable names was minimized in order to limit problems with the code integration. Since the remaining stability problems of DeCART were mostly caused by the CMFD methodology and modules, significant work was performed to determine whether they could be replaced by more stable methods and routines. The cross section library is a key element to obtain accurate solutions. Thus, the procedure for generating cross section libraries was revisited to provide libraries tailored for the targeted reactor types. To improve accuracy in the cross section library, an attempt was made to replace the CENTRM code by the MCNP Monte Carlo code as a tool obtaining reference resonance integrals. The use of the Monte Carlo code allows us to minimize problems or approximations that CENTRM introduces since the accuracy of the subgroup data is limited by that of the reference solutions. The use of MCNP requires an additional set of libraries without resonance cross sections so that reference calculations can be performed for a unit cell in which only one isotope of interest includes resonance cross sections, among the isotopes in the composition. The OECD MHTGR-350 benchmark core was simulated using DeCART as initial focus of the verification/validation efforts. Among the benchmark problems, Exercise 1 of Phase 1 is a steady-state benchmark case for the neutronics calculation for which block-wise cross sections were provided in 26 energy groups. This type of problem was designed for a homogenized geometry solver like DIF3D rather than the high-fidelity code DeCART. Instead of the homogenized block cross sections given in the benchmark, the VHTR-specific 238-group ENDF/B-VII.0 library of DeCART was directly used for preliminary calculations. Initial results showed that the multiplication factors of a fuel pin and a fuel block with or without a control rod hole were off by 6, -362, and -183 pcm Dk from comparable MCNP solutions, respectively. The 2-D and 3-D one-third core calculations were also conducted for the all-rods-out (ARO) and all-rods-in (ARI) configurations, producing reasonable results. Figure 1 illustrates the intermediate (1.5 eV - 17 keV) and thermal (below 1.5 eV) group flux distributions. As seen from VHTR cores with annular fuels, the intermediate group fluxes are relatively high in the fuel region, but the thermal group fluxes are higher in the inner and outer graphite reflector regions than in the fuel region. To support the current project, a new three-year I-NERI collaboration involving ANL and KAERI was started in November 2011, focused on performing in-depth verification and validation of high-fidelity multi-physics simulation codes for LWR and VHTR. The work scope includes generating improved cross section libraries for the targeted reactor types, developing benchmark models for verification and validation of the neutronics code with or without thermo-fluid feedback, and performing detailed comparisons of predicted reactor parameters against both Monte Carlo solutions and experimental measurements. The following list summarizes the work conducted so far for PROTEUS-Thermal Tasks: Unification of different versions of DeCART was initiated, and at the same time code modernization was conducted to make code unification efficient; (2) Regeneration of cross section libraries was attempted for the targeted reactor types, and the procedure for generating cross section libraries was updated by replacing CENTRM with MCNP for reference resonance integrals; (3) The MHTGR-350 benchmark core was simulated using DeCART with VHTR-specific 238-group ENDF/B-VII.0 library, and MCNP calculations were performed for comparison; and (4) Benchmark problems for PWR and BWR analysis were prepared for the DeCART verification/validation effort. In the coming months, the work listed above will be completed. Cross section libraries will be generated with optimized group structures for specific reactor types.« less

A solid reactor core thermal model for nuclear thermal rockets

NASA Astrophysics Data System (ADS)

Rider, William J.; Cappiello, Michael W.; Liles, Dennis R.

1991-01-01

A Helium/Hydrogen Cooled Reactor Analysis (HERA) computer code has been developed. HERA has the ability to model arbitrary geometries in three dimensions, which allows the user to easily analyze reactor cores constructed of prismatic graphite elements. The code accounts for heat generation in the fuel, control rods, and other structures; conduction and radiation across gaps; convection to the coolant; and a variety of boundary conditions. The numerical solution scheme has been optimized for vector computers, making long transient analyses economical. Time integration is either explicit or implicit, which allows the use of the model to accurately calculate both short- or long-term transients with an efficient use of computer time. Both the basic spatial and temporal integration schemes have been benchmarked against analytical solutions.

Analysis of new measurements of Calvert Cliffs spent fuel samples using SCALE 6.2

DOE PAGES

Hu, Jianwei; Giaquinto, J. M.; Gauld, I. C.; ...

2017-04-28

High quality experimental data for isotopic compositions in irradiated fuel are important to spent fuel applications, including nuclear safeguards, spent fuel storage, transportation, and final disposal. The importance of these data has been increasingly recognized in recent years, particularly as countries like Finland and Sweden plan to open the world’s first two spent fuel geological repositories in 2020s, while other countries, including the United States, are considering extended dry fuel storage options. Destructive and nondestructive measurements of a spent fuel rod segment from a Combustion Engineering 14 × 14 fuel assembly of the Calvert Cliffs Unit 1 nuclear reactor havemore » been recently performed at Oak Ridge National Laboratory (ORNL). These ORNL measurements included two samples selected from adjacent axial locations of a fuel rod with initial enrichment of 3.038 wt% 235U, which achieved burnups close to 43.5 GWd/MTU. More than 50 different isotopes of 16 elements were measured using high precision measurement methods. Various investigations have assessed the quality of the new ORNL measurement data, including comparison to previous measurements and to calculation results. Previous measurement data for samples from the same fuel rod measured at ORNL are available from experiments performed at Pacific Northwest National Laboratory in the United States and the Khoplin Radium Institute in Russia. Detailed assembly models were developed using the newly released SCALE 6.2 code package to simulate depletion and decay of the measured fuel samples. Furthermore, results from this work show that the new ORNL measurements provide a good quality radiochemical assay data set for spent fuel with relatively high burnup and long cooling time, and they can serve as good benchmark data for nuclear burnup code validation and spent fuel studies.« less

Analysis of new measurements of Calvert Cliffs spent fuel samples using SCALE 6.2

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

Hu, Jianwei; Giaquinto, J. M.; Gauld, I. C.

High quality experimental data for isotopic compositions in irradiated fuel are important to spent fuel applications, including nuclear safeguards, spent fuel storage, transportation, and final disposal. The importance of these data has been increasingly recognized in recent years, particularly as countries like Finland and Sweden plan to open the world’s first two spent fuel geological repositories in 2020s, while other countries, including the United States, are considering extended dry fuel storage options. Destructive and nondestructive measurements of a spent fuel rod segment from a Combustion Engineering 14 × 14 fuel assembly of the Calvert Cliffs Unit 1 nuclear reactor havemore » been recently performed at Oak Ridge National Laboratory (ORNL). These ORNL measurements included two samples selected from adjacent axial locations of a fuel rod with initial enrichment of 3.038 wt% 235U, which achieved burnups close to 43.5 GWd/MTU. More than 50 different isotopes of 16 elements were measured using high precision measurement methods. Various investigations have assessed the quality of the new ORNL measurement data, including comparison to previous measurements and to calculation results. Previous measurement data for samples from the same fuel rod measured at ORNL are available from experiments performed at Pacific Northwest National Laboratory in the United States and the Khoplin Radium Institute in Russia. Detailed assembly models were developed using the newly released SCALE 6.2 code package to simulate depletion and decay of the measured fuel samples. Furthermore, results from this work show that the new ORNL measurements provide a good quality radiochemical assay data set for spent fuel with relatively high burnup and long cooling time, and they can serve as good benchmark data for nuclear burnup code validation and spent fuel studies.« less

Experimental critical loadings and control rod worths in LWR-PROTEUS configurations compared with MCNPX results

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

Plaschy, M.; Murphy, M.; Jatuff, F.

2006-07-01

The PROTEUS research reactor at the Paul Scherrer Inst. (PSI) has been operating since the sixties and has already permitted, due to its high flexibility, investigation of a large range of very different nuclear systems. Currently, the ongoing experimental programme is called LWR-PROTEUS. This programme was started in 1997 and concerns large-scale investigations of advanced light water reactors (LWR) fuels. Until now, the different LWR-PROTEUS phases have permitted to study more than fifteen different configurations, each of them having to be demonstrated to be operationally safe, in particular, for the Swiss safety authorities. In this context, recent developments of themore » PSI computer capabilities have made possible the use of full-scale SD-heterogeneous MCNPX models to calculate accurately different safety related parameters (e.g. the critical driver loading and the shutdown rod worth). The current paper presents the MCNPX predictions of these operational characteristics for seven different LWR-PROTEUS configurations using a large number of nuclear data libraries. More specifically, this significant benchmarking exercise is based on the ENDF/B6v2, ENDF/B6v8, JEF2.2, JEFF3.0, JENDL3.2, and JENDL3.3 libraries. The results highlight certain library specific trends in the prediction of the multiplication factor k{sub eff} (e.g. the systematically larger reactivity calculated with JEF2.2 and the smaller reactivity associated with JEFF3.0). They also confirm the satisfactory determination of reactivity variations by all calculational schemes, for instance, due to the introduction of a safety rod pair, these calculations having been compared with experiments. (authors)« less

Results of a Neutronic Simulation of HTR-Proteus Core 4.2 using PEBBED and other INL Reactor Physics Tools: FY-09 Report

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

Hans D. Gougar

The Idaho National Laboratory’s deterministic neutronics analysis codes and methods were applied to the computation of the core multiplication factor of the HTR-Proteus pebble bed reactor critical facility. A combination of unit cell calculations (COMBINE-PEBDAN), 1-D discrete ordinates transport (SCAMP), and nodal diffusion calculations (PEBBED) were employed to yield keff and flux profiles. Preliminary results indicate that these tools, as currently configured and used, do not yield satisfactory estimates of keff. If control rods are not modeled, these methods can deliver much better agreement with experimental core eigenvalues which suggests that development efforts should focus on modeling control rod andmore » other absorber regions. Under some assumptions and in 1D subcore analyses, diffusion theory agrees well with transport. This suggests that developments in specific areas can produce a viable core simulation approach. Some corrections have been identified and can be further developed, specifically: treatment of the upper void region, treatment of inter-pebble streaming, and explicit (multiscale) transport modeling of TRISO fuel particles as a first step in cross section generation. Until corrections are made that yield better agreement with experiment, conclusions from core design and burnup analyses should be regarded as qualitative and not benchmark quality.« less

In Situ Gene Therapy via AAV-CRISPR-Cas9-Mediated Targeted Gene Regulation.

PubMed

Moreno, Ana M; Fu, Xin; Zhu, Jie; Katrekar, Dhruva; Shih, Yu-Ru V; Marlett, John; Cabotaje, Jessica; Tat, Jasmine; Naughton, John; Lisowski, Leszek; Varghese, Shyni; Zhang, Kang; Mali, Prashant

2018-04-25

Development of efficacious in vivo delivery platforms for CRISPR-Cas9-based epigenome engineering will be critical to enable the ability to target human diseases without permanent modification of the genome. Toward this, we utilized split-Cas9 systems to develop a modular adeno-associated viral (AAV) vector platform for CRISPR-Cas9 delivery to enable the full spectrum of targeted in situ gene regulation functionalities, demonstrating robust transcriptional repression (up to 80%) and activation (up to 6-fold) of target genes in cell culture and mice. We also applied our platform for targeted in vivo gene-repression-mediated gene therapy for retinitis pigmentosa. Specifically, we engineered targeted repression of Nrl, a master regulator of rod photoreceptor determination, and demonstrated Nrl knockdown mediates in situ reprogramming of rod cells into cone-like cells that are resistant to retinitis pigmentosa-specific mutations, with concomitant prevention of secondary cone loss. Furthermore, we benchmarked our results from Nrl knockdown with those from in vivo Nrl knockout via gene editing. Taken together, our AAV-CRISPR-Cas9 platform for in vivo epigenome engineering enables a robust approach to target disease in a genomically scarless and potentially reversible manner. Copyright © 2018 The American Society of Gene and Cell Therapy. Published by Elsevier Inc. All rights reserved.

Experimental results from the VENUS-F critical reference state for the GUINEVERE accelerator driven system project

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

Uyttenhove, W.; Baeten, P.; Kochetkov, A.

The GUINEVERE (Generation of Uninterrupted Intense Neutron pulses at the lead Venus Reactor) project was launched in 2006 within the framework of FP6 EUROTRANS in order to validate online reactivity monitoring and subcriticality level determination in accelerator driven systems (ADS). Therefore, the VENUS reactor at SCK.CEN in Mol, Belgium, was modified towards a fast core (VENUS-F) and coupled to the GENEPI-3C accelerator built by CNRS. The accelerator can operate in both continuous and pulsed mode. The VENUS-F core is loaded with enriched Uranium and reflected with solid lead. A well-chosen critical reference state is indispensable for the validation of themore » online subcriticality monitoring methodology. Moreover, a benchmarking tool is required for nuclear data research and code validation. In this paper, the design and the importance of the critical reference state for the GUINEVERE project are motivated. The results of the first experimental phase on the critical core are presented. The control rods worth is determined by the positive period method and the application of the Modified Source Multiplication (MSM) method allows the determination of the worth of the safety rods. The results are implemented in the VENUS-F core certificate for full exploitation of the critical core. (authors)« less

Nuclear reactor

DOEpatents

Yant, Howard W.; Stinebiser, Karl W.; Anzur, Gregory C.

1977-01-01

A nuclear reactor, particularly a liquid-metal breeder reactor, whose upper internals include outlet modules for channeling the liquid-metal coolant from selected areas of the outlet of the core vertically to the outlet plenum. The modules are composed of a highly-refractory, high corrosion-resistant alloy, for example, INCONEL-718. Each module is disposed to confine and channel generally vertically the coolant emitted from a subplurality of core-component assemblies. Each module has a grid with openings, each opening disposed to receive the coolant from an assembly of the subplurality. The grid in addition serves as a holdown for the assemblies of the corresponding subplurality preventing their excessive ejection upwardly from the core. In the region directly over the core the outlet modules are of such peripheral form that they nest forming a continuum over the core-component assemblies whose outlet coolant they confine. Each subassembly includes a chimney which confines the coolant emitted by its corresponding subassemblies to generally vertical flow between the outlet of the core and the outlet plenum. Each subplurality of assemblies whose emitted coolant is confined by an outlet module includes assemblies which emit lower-temperature coolant, for example, a control-rod assembly, or fertile assemblies, and assemblies which emit coolant of substantially higher temperature, for example, fuel-rod assemblies. The coolants of different temperatures are mixed in the chimneys reducing the effect of stripping (hot-cold temperature fluctuations) on the remainder of the upper internals which are composed typically of AISI-304 or AISI-316 stainless steel.

Application of Jacobian-free Newton–Krylov method in implicitly solving two-fluid six-equation two-phase flow problems: Implementation, validation and benchmark

DOE PAGES

Zou, Ling; Zhao, Haihua; Zhang, Hongbin

2016-03-09

This work represents a first-of-its-kind successful application to employ advanced numerical methods in solving realistic two-phase flow problems with two-fluid six-equation two-phase flow model. These advanced numerical methods include high-resolution spatial discretization scheme with staggered grids (high-order) fully implicit time integration schemes, and Jacobian-free Newton–Krylov (JFNK) method as the nonlinear solver. The computer code developed in this work has been extensively validated with existing experimental flow boiling data in vertical pipes and rod bundles, which cover wide ranges of experimental conditions, such as pressure, inlet mass flux, wall heat flux and exit void fraction. Additional code-to-code benchmark with the RELAP5-3Dmore » code further verifies the correct code implementation. The combined methods employed in this work exhibit strong robustness in solving two-phase flow problems even when phase appearance (boiling) and realistic discrete flow regimes are considered. Transitional flow regimes used in existing system analysis codes, normally introduced to overcome numerical difficulty, were completely removed in this work. As a result, this in turn provides the possibility to utilize more sophisticated flow regime maps in the future to further improve simulation accuracy.« less

Connecting white light to in situ observations of 22 coronal mass ejections from the Sun to 1 AU

NASA Astrophysics Data System (ADS)

Moestl, C.; Amla, K.; Farrugia, C. J.; Hall, J. R.; Liewer, P. C.; De Jong, E.; Colaninno, R. C.; Vourlidas, A.; Veronig, A. M.; Rollett, T.; Temmer, M.; Peinhart, V.; Davies, J.; Lugaz, N.; Liu, Y. D.; McEnulty, T.; Luhmann, J. G.; Galvin, A. B.

2013-12-01

We study the feasibility of using a Heliospheric Imager (HI) instrument, such as STEREO/HI, for unambiguously connecting remote images to in situ observations of coronal mass ejection (CMEs). Our goal is to develop and test methods to predict CME parameters from heliospheric images, but our dataset can actually be used to benchmark any ICME propagation model. The results are of interest concerning future missions such as Solar Orbiter, or a dedicated space weather mission at the Sun-Earth L5 point (e.g. EASCO mission concept). We compare the predictions for speed and arrival time for 22 CME events (between 2008-2012), each observed remotely by one STEREO spacecraft, to the interplanetary coronal mass ejection (ICME) speed and arrival time observed at in situ observatories (STEREO PLASTIC/IMPACT, Wind SWE/MFI). We use forward modeling for STEREO-COR2, and geometrical models for STEREO-HII, assuming different CME front shapes (Fixed-Phi, Harmonic Mean, Self-similar expansion), and fit them to the CME time-elongation functions with the SolarSoft SATPLOT tool, assuming constant CME speed and direction. The arrival times derived from imaging match the in situ ones +/- 8 hours, and speeds are consistent within +/-300 km/s, including CME apex/flank effects. We find no preference in the predictive capability for any of the 3 geometries used on the full dataset, consisting of front- and backsided, slow and fast CMEs (up to 2700 km/s). We search for new empirical relations between the predicted and observed speeds and arrival times, enhancing the HI predictive capabilities. Additionally, for very fast and back-sided CMEs, strong differences between the results of the HI models arise, consistent with theoretical expectations by Lugaz and Kintner (2013, Solar Physics). This work has received funding from the European Commission FP7 Project COMESEP (263252).

TREAT Transient Analysis Benchmarking for the HEU Core

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

Kontogeorgakos, D. C.; Connaway, H. M.; Wright, A. E.

2014-05-01

This work was performed to support the feasibility study on the potential conversion of the Transient Reactor Test Facility (TREAT) at Idaho National Laboratory from the use of high enriched uranium (HEU) fuel to the use of low enriched uranium (LEU) fuel. The analyses were performed by the GTRI Reactor Conversion staff at the Argonne National Laboratory (ANL). The objective of this study was to benchmark the transient calculations against temperature-limited transients performed in the final operating HEU TREAT core configuration. The MCNP code was used to evaluate steady-state neutronics behavior, and the point kinetics code TREKIN was used tomore » determine core power and energy during transients. The first part of the benchmarking process was to calculate with MCNP all the neutronic parameters required by TREKIN to simulate the transients: the transient rod-bank worth, the prompt neutron generation lifetime, the temperature reactivity feedback as a function of total core energy, and the core-average temperature and peak temperature as a functions of total core energy. The results of these calculations were compared against measurements or against reported values as documented in the available TREAT reports. The heating of the fuel was simulated as an adiabatic process. The reported values were extracted from ANL reports, intra-laboratory memos and experiment logsheets and in some cases it was not clear if the values were based on measurements, on calculations or a combination of both. Therefore, it was decided to use the term “reported” values when referring to such data. The methods and results from the HEU core transient analyses will be used for the potential LEU core configurations to predict the converted (LEU) core’s performance.« less

Application of probabilistic risk assessment: Evaluating remedial alternatives at the Portland Harbor Superfund Site, Portland, Oregon, USA.

PubMed

Ruffle, Betsy; Henderson, James; Murphy-Hagan, Clare; Kirkwood, Gemma; Wolf, Frederick; Edwards, Deborah A

2018-01-01

A probabilistic risk assessment (PRA) was performed to evaluate the range of potential baseline and postremedy health risks to fish consumers at the Portland Harbor Superfund Site (the "Site"). The analysis focused on risks of consuming fish resident to the Site containing polychlorinated biphenyls (PCBs), given that this exposure scenario and contaminant are the primary basis for US Environmental Protection Agency's (USEPA's) selected remedy per the January 2017 Record of Decision (ROD). The PRA used probability distributions fit to the same data sets used in the deterministic baseline human health risk assessment (BHHRA) as well as recent sediment and fish tissue data to evaluate the range and likelihood of current baseline cancer risks and noncancer hazards for anglers. Areas of elevated PCBs in sediment were identified on the basis of a geospatial evaluation of the surface sediment data, and the ranges of risks and hazards associated with pre- and postremedy conditions were calculated. The analysis showed that less active remediation (targeted to areas with the highest concentrations) compared to the remedial alternative selected by USEPA in the ROD can achieve USEPA's interim risk management benchmarks (cancer risk of 10 -4 and noncancer hazard index [HI] of 10) immediately postremediation for the vast majority of subsistence anglers that consume smallmouth bass (SMB) fillet tissue. In addition, the same targeted remedy achieves USEPA's long-term benchmarks (10 -5 and HI of 1) for the majority of recreational anglers. Additional sediment remediation would result in negligible additional risk reduction due to the influence of background. The PRA approach applied here provides a simple but adaptive framework for analysis of risks and remedial options focused on variability in exposures. It can be updated and refined with new data to evaluate and reduce uncertainty, improve understanding of the Site and target populations, and foster informed remedial decision making. Integr Environ Assess Manag 2018;14:63-78. © 2017 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals, Inc. on behalf of Society of Environmental Toxicology & Chemistry (SETAC). © 2017 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals, Inc. on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Calculation of the Phenix end-of-life test 'Control Rod Withdrawal' with the ERANOS code

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

Tiberi, V.

2012-07-01

The Inst. of Radiological Protection and Nuclear Safety (IRSN) acts as technical support to French public authorities. As such, IRSN is in charge of safety assessment of operating and under construction reactors, as well as future projects. In this framework, one current objective of IRSN is to evaluate the ability and accuracy of numerical tools to foresee consequences of accidents. Neutronic studies step in the safety assessment from different points of view among which the core design and its protection system. They are necessary to evaluate the core behavior in case of accident in order to assess the integrity ofmore » the first barrier and the absence of a prompt criticality risk. To reach this objective one main physical quantity has to be evaluated accurately: the neutronic power distribution in core during whole reactor lifetime. Phenix end of life tests, carried out in 2009, aim at increasing the experience feedback on sodium cooled fast reactors. These experiments have been done in the framework of the development of the 4. generation of nuclear reactors. Ten tests have been carried out: 6 on neutronic and fuel aspects, 2 on thermal hydraulics and 2 for the emergency shutdown. Two of them have been chosen for an international exercise on thermal hydraulics and neutronics in the frame of an IAEA Coordinated Research Project. Concerning neutronics, the Control Rod Withdrawal test is relevant for safety because it allows evaluating the capability of calculation tools to compute the radial power distribution on fast reactors core configurations in which the flux field is very deformed. IRSN participated to this benchmark with the ERANOS code developed by CEA for fast reactors studies. This paper presents the results obtained in the framework of the benchmark activity. A relatively good agreement was found with available measures considering the approximations done in the modeling. The work underlines the importance of burn-up calculations in order to have a fine core concentrations mesh for the calculation of the power distribution. (authors)« less

HTR-PROTEUS PEBBLE BED EXPERIMENTAL PROGRAM CORE 4: RANDOM PACKING WITH A 1:1 MODERATOR-TO-FUEL PEBBLE RATIO

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

John D. Bess; Leland M. Montierth

2013-03-01

In its deployment as a pebble bed reactor (PBR) critical facility from 1992 to 1996, the PROTEUS facility was designated as HTR-PROTEUS. This experimental program was performed as part of an International Atomic Energy Agency (IAEA) Coordinated Research Project (CRP) on the Validation of Safety Related Physics Calculations for Low Enriched HTGRs. Within this project, critical experiments were conducted for graphite moderated LEU systems to determine core reactivity, flux and power profiles, reaction-rate ratios, the worth of control rods, both in-core and reflector based, the worth of burnable poisons, kinetic parameters, and the effects of moisture ingress on these parameters.more » One benchmark experiment was evaluated in this report: Core 4. Core 4 represents the only configuration with random pebble packing in the HTR-PROTEUS series of experiments, and has a moderator-to-fuel pebble ratio of 1:1. Three random configurations were performed. The initial configuration, Core 4.1, was rejected because the method for pebble loading, separate delivery tubes for the moderator and fuel pebbles, may not have been completely random; this core loading was rejected by the experimenters. Cores 4.2 and 4.3 were loaded using a single delivery tube, eliminating the possibility for systematic ordering effects. The second and third cores differed slightly in the quantity of pebbles loaded (40 each of moderator and fuel pebbles), stacked height of the pebbles in the core cavity (0.02 m), withdrawn distance of the stainless steel control rods (20 mm), and withdrawn distance of the autorod (30 mm). The 34 coolant channels in the upper axial reflector and the 33 coolant channels in the lower axial reflector were open. Additionally, the axial graphite fillers used in all other HTR-PROTEUS configurations to create a 12-sided core cavity were not used in the randomly packed cores. Instead, graphite fillers were placed on the cavity floor, creating a funnel-like base, to discourage ordering effects during pebble loading. Core 4 was determined to be acceptable benchmark experiment.« less

HTR-proteus pebble bed experimental program core 4: random packing with a 1:1 moderator-to-fuel pebble ratio

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

Bess, John D.; Montierth, Leland M.; Sterbentz, James W.

2014-03-01

In its deployment as a pebble bed reactor (PBR) critical facility from 1992 to 1996, the PROTEUS facility was designated as HTR-PROTEUS. This experimental program was performed as part of an International Atomic Energy Agency (IAEA) Coordinated Research Project (CRP) on the Validation of Safety Related Physics Calculations for Low Enriched HTGRs. Within this project, critical experiments were conducted for graphite moderated LEU systems to determine core reactivity, flux and power profiles, reaction-rate ratios, the worth of control rods, both in-core and reflector based, the worth of burnable poisons, kinetic parameters, and the effects of moisture ingress on these parameters.more » One benchmark experiment was evaluated in this report: Core 4. Core 4 represents the only configuration with random pebble packing in the HTR-PROTEUS series of experiments, and has a moderator-to-fuel pebble ratio of 1:1. Three random configurations were performed. The initial configuration, Core 4.1, was rejected because the method for pebble loading, separate delivery tubes for the moderator and fuel pebbles, may not have been completely random; this core loading was rejected by the experimenters. Cores 4.2 and 4.3 were loaded using a single delivery tube, eliminating the possibility for systematic ordering effects. The second and third cores differed slightly in the quantity of pebbles loaded (40 each of moderator and fuel pebbles), stacked height of the pebbles in the core cavity (0.02 m), withdrawn distance of the stainless steel control rods (20 mm), and withdrawn distance of the autorod (30 mm). The 34 coolant channels in the upper axial reflector and the 33 coolant channels in the lower axial reflector were open. Additionally, the axial graphite fillers used in all other HTR-PROTEUS configurations to create a 12-sided core cavity were not used in the randomly packed cores. Instead, graphite fillers were placed on the cavity floor, creating a funnel-like base, to discourage ordering effects during pebble loading. Core 4 was determined to be acceptable benchmark experiment.« less

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

Bailey, David H.

The NAS Parallel Benchmarks (NPB) are a suite of parallel computer performance benchmarks. They were originally developed at the NASA Ames Research Center in 1991 to assess high-end parallel supercomputers. Although they are no longer used as widely as they once were for comparing high-end system performance, they continue to be studied and analyzed a great deal in the high-performance computing community. The acronym 'NAS' originally stood for the Numerical Aeronautical Simulation Program at NASA Ames. The name of this organization was subsequently changed to the Numerical Aerospace Simulation Program, and more recently to the NASA Advanced Supercomputing Center, althoughmore » the acronym remains 'NAS.' The developers of the original NPB suite were David H. Bailey, Eric Barszcz, John Barton, David Browning, Russell Carter, LeoDagum, Rod Fatoohi, Samuel Fineberg, Paul Frederickson, Thomas Lasinski, Rob Schreiber, Horst Simon, V. Venkatakrishnan and Sisira Weeratunga. The original NAS Parallel Benchmarks consisted of eight individual benchmark problems, each of which focused on some aspect of scientific computing. The principal focus was in computational aerophysics, although most of these benchmarks have much broader relevance, since in a much larger sense they are typical of many real-world scientific computing applications. The NPB suite grew out of the need for a more rational procedure to select new supercomputers for acquisition by NASA. The emergence of commercially available highly parallel computer systems in the late 1980s offered an attractive alternative to parallel vector supercomputers that had been the mainstay of high-end scientific computing. However, the introduction of highly parallel systems was accompanied by a regrettable level of hype, not only on the part of the commercial vendors but even, in some cases, by scientists using the systems. As a result, it was difficult to discern whether the new systems offered any fundamental performance advantage over vector supercomputers, and, if so, which of the parallel offerings would be most useful in real-world scientific computation. In part to draw attention to some of the performance reporting abuses prevalent at the time, the present author wrote a humorous essay 'Twelve Ways to Fool the Masses,' which described in a light-hearted way a number of the questionable ways in which both vendor marketing people and scientists were inflating and distorting their performance results. All of this underscored the need for an objective and scientifically defensible measure to compare performance on these systems.« less

Benchmark Accelerated Aging of Harvested Hypalon/Epr and Cspe/Xlpe Power and I&C Cable in Nuclear Power Plants

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

Duckworth, Robert C.; Frame, Emily; Fifield, Leonard S.

As part of the Light Water Reactor and Sustainability (LWRS) program in the U.S. Department of Energy (DOE) Office of Nuclear Energy, material aging and degradation research is currently geared to support the long-term operation of existing nuclear power plants (NPPs) as they move beyond their initial 40 year licenses. The goal of this research is to provide information so that NPPs can develop aging management programs (AMPs) to address replacement and monitoring needs as they look to operate for 20 years, and in some cases 40 years, beyond their initial operating lifetimes. For cable insulation and jacket materials thatmore » support instrument, control, and safety systems, accelerated aging data are needed to determine priorities in cable aging management programs. Before accelerated thermal and radiation aging of harvested, representative cable insulation and jacket materials, the benchmark performance of a new test capability at Oak Ridge National Laboratory (ORNL) was evaluated for temperatures between 70 and 135°C, dose rates between 100 and 500 Gy/h, and accumulated doses up to 20 kGy, Samples that were characterized and are representative of current materials in use were harvested from the Callaway NPP near Fulton, Missouri, and the San Onofre NPP north of San Diego, California. From the Callaway NPP, a multiconductor control rod cable manufactured by Boston Insulated Wire (BIW), with a Hypalon/ chorolosulfonated polyethylene (CSPE) jacket and ethylene-propylene rubber (EPR) insulation, was harvested from the auxiliary space during a planned outage in 2013. This cable was placed into service when the plant was started in 1984. From the San Onofre NPP, a Rockbestos Firewall III (FRIII) cable with a Hypalon/ CSPE jacket with cross-linked polyethylene (XLPE) insulation was harvested from an on-site, climate-controlled storage area. This conductor, which was never placed into service, was procured around 2007 in anticipation of future operation that did not occur. Benchmark aging for both jacket and insulation material was carried out in air at a temperature of 125°C or in uniform 140 Gy/h gamma irradiation over a period of 60 days. Their mechanical properties over the course of their exposures were compared with reference data from comparable cable jacket/insulation compositions and aging conditions. For both accelerated thermal and radiation aging, it was observed that the mechanical properties for the Callaway BIW control rod cable were consistent with those previously measured. However, for the San Onofre Rockbestos FRIII, there was an observable functional difference for accelerated thermal aging at 125°C. Details on possible sources for this difference and plans for resolving each source are given in this paper.« less

BENCHMARK ACCELERATED AGING OF HARVESTED HYPALON/EPR AND CSPE/XLPE POWER AND I&C CABLE IN NUCLEAR POWER PLANTS

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

Duckworth, Robert C; Fifield, Dr Leonard S

As part of the Light Water Reactor and Sustainability (LWRS) program in the U.S. Department of Energy (DOE) Office of Nuclear Energy, material aging and degradation research is currently geared to support the long-term operation of existing nuclear power plants (NPPs) as they move beyond their initial 40 year licenses. The goal of this research is to provide information so that NPPs can develop aging management programs (AMPs) to address replacement and monitoring needs as they look to operate for 20 years, and in some cases 40 years, beyond their initial operating lifetimes. For cable insulation and jacket materials thatmore » support instrument, control, and safety systems, accelerated aging data are needed to determine priorities in cable aging management programs. Before accelerated thermal and radiation aging of harvested, representative cable insulation and jacket materials, the benchmark performance of a new test capability at Oak Ridge National Laboratory (ORNL) was evaluated for temperatures between 70 and 135 C, dose rates between 100 and 500 Gy/h, and accumulated doses up to 20 kGy, Samples that were characterized and are representative of current materials in use were harvested from the Callaway NPP near Fulton, Missouri, and the San Onofre NPP north of San Diego, California. From the Callaway NPP, a multiconductor control rod cable manufactured by Boston Insulated Wire (BIW), with a Hypalon/ chorolosulfonated polyethylene (CSPE) jacket and ethylene-propylene rubber (EPR) insulation, was harvested from the auxiliary space during a planned outage in 2013. This cable was placed into service when the plant was started in 1984. From the San Onofre NPP, a Rockbestos Firewall III (FRIII) cable with a Hypalon/ CSPE jacket with cross-linked polyethylene (XLPE) insulation was harvested from an on-site, climate-controlled storage area. This conductor, which was never placed into service, was procured around 2007 in anticipation of future operation that did not occur. Benchmark aging for both jacket and insulation material was carried out in air at a temperature of 125 C or in uniform 140 Gy/h gamma irradiation over a period of 60 days. Their mechanical properties over the course of their exposures were compared with reference data from comparable cable jacket/insulation compositions and aging conditions. For both accelerated thermal and radiation aging, it was observed that the mechanical properties for the Callaway BIW control rod cable were consistent with those previously measured. However, for the San Onofre Rockbestos FRIII, there was an observable functional difference for accelerated thermal aging at 125 C. Details on possible sources for this difference and plans for resolving each source are given in this paper.« less

Analysis of Links Positions in Landing Gear Mechanism

NASA Astrophysics Data System (ADS)

Brewczyński, D.; Tora, G.

2014-08-01

This article contains a kinematic analysis of an aircraft chassis mechanism in a range of positions. The mechanism of the chassis is made up of several smaller subsystems with different functions. The first mechanism is used to eject the chassis before landing (touchdown) and fold it to hatchway after the lift off. The second mechanism is designed to perform rotation of the crossover with the wheel, in order to adjust the position of the wheel to fit it in the limited space in the hold. The third mechanism allows movement of the chassis resulting from the change in length of the damper. To determine the position of the following links of the mechanism calculus of vectors was applied in which unit vectors were used to represent the angular position of the links. The aim of the analysis is to determine the angle of convergence and the angle of heel wheels as a function of the variable length of hydraulic cylinder, length of the shock absorber, length of the regulations rods

Untangling ciliary access and enrichment of two rhodopsin-like receptors using quantitative fluorescence microscopy reveals cell-specific sorting pathways

PubMed Central

Geneva, Ivayla I.; Tan, Han Yen; Calvert, Peter D.

2017-01-01

Resolution limitations of optical systems are major obstacles for determining whether proteins are enriched within cell compartments. Here we use an approach to determine the degree of membrane protein ciliary enrichment that quantitatively accounts for the differences in sampling of the ciliary and apical membranes inherent to confocal microscopes. Theory shows that cilia will appear more than threefold brighter than the surrounding apical membrane when the densities of fluorescently labeled proteins are the same, thus providing a benchmark for ciliary enrichment. Using this benchmark, we examined the ciliary enrichment signals of two G protein–coupled receptors (GPCRs)—the somatostatin receptor 3 and rhodopsin. Remarkably, we found that the C-terminal VxPx motif, required for efficient enrichment of rhodopsin within rod photoreceptor sensory cilia, inhibited enrichment of the somatostatin receptor in primary cilia. Similarly, VxPx inhibited primary cilium enrichment of a chimera of rhodopsin and somatostatin receptor 3, where the dual Ax(S/A)xQ ciliary targeting motifs within the third intracellular loop of the somatostatin receptor replaced the third intracellular loop of rhodopsin. Rhodopsin was depleted from primary cilia but gained access, without being enriched, with the dual Ax(S/A)xQ motifs. Ciliary enrichment of these GPCRs thus operates via distinct mechanisms in different cells. PMID:27974638

Monte Carlo chord length sampling for d-dimensional Markov binary mixtures

NASA Astrophysics Data System (ADS)

Larmier, Coline; Lam, Adam; Brantley, Patrick; Malvagi, Fausto; Palmer, Todd; Zoia, Andrea

2018-01-01

The Chord Length Sampling (CLS) algorithm is a powerful Monte Carlo method that models the effects of stochastic media on particle transport by generating on-the-fly the material interfaces seen by the random walkers during their trajectories. This annealed disorder approach, which formally consists of solving the approximate Levermore-Pomraning equations for linear particle transport, enables a considerable speed-up with respect to transport in quenched disorder, where ensemble-averaging of the Boltzmann equation with respect to all possible realizations is needed. However, CLS intrinsically neglects the correlations induced by the spatial disorder, so that the accuracy of the solutions obtained by using this algorithm must be carefully verified with respect to reference solutions based on quenched disorder realizations. When the disorder is described by Markov mixing statistics, such comparisons have been attempted so far only for one-dimensional geometries, of the rod or slab type. In this work we extend these results to Markov media in two-dimensional (extruded) and three-dimensional geometries, by revisiting the classical set of benchmark configurations originally proposed by Adams, Larsen and Pomraning [1] and extended by Brantley [2]. In particular, we examine the discrepancies between CLS and reference solutions for scalar particle flux and transmission/reflection coefficients as a function of the material properties of the benchmark specifications and of the system dimensionality.

Monte Carlo chord length sampling for d-dimensional Markov binary mixtures

DOE PAGES

Larmier, Coline; Lam, Adam; Brantley, Patrick; ...

2017-09-27

The Chord Length Sampling (CLS) algorithm is a powerful Monte Carlo method that models the effects of stochastic media on particle transport by generating on-the-fly the material interfaces seen by the random walkers during their trajectories. This annealed disorder approach, which formally consists of solving the approximate Levermore–Pomraning equations for linear particle transport, enables a considerable speed-up with respect to transport in quenched disorder, where ensemble-averaging of the Boltzmann equation with respect to all possible realizations is needed. However, CLS intrinsically neglects the correlations induced by the spatial disorder, so that the accuracy of the solutions obtained by using thismore » algorithm must be carefully verified with respect to reference solutions based on quenched disorder realizations. When the disorder is described by Markov mixing statistics, such comparisons have been attempted so far only for one-dimensional geometries, of the rod or slab type. In this work we extend these results to Markov media in two-dimensional (extruded) and three-dimensional geometries, by revisiting the classical set of benchmark configurations originally proposed by Adams, Larsen and Pomraning and extended by Brantley. In particular, we examine the discrepancies between CLS and reference solutions for scalar particle flux and transmission/reflection coefficients as a function of the material properties of the benchmark specifications and of the system dimensionality.« less

Monte Carlo chord length sampling for d-dimensional Markov binary mixtures

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

Larmier, Coline; Lam, Adam; Brantley, Patrick

The Chord Length Sampling (CLS) algorithm is a powerful Monte Carlo method that models the effects of stochastic media on particle transport by generating on-the-fly the material interfaces seen by the random walkers during their trajectories. This annealed disorder approach, which formally consists of solving the approximate Levermore–Pomraning equations for linear particle transport, enables a considerable speed-up with respect to transport in quenched disorder, where ensemble-averaging of the Boltzmann equation with respect to all possible realizations is needed. However, CLS intrinsically neglects the correlations induced by the spatial disorder, so that the accuracy of the solutions obtained by using thismore » algorithm must be carefully verified with respect to reference solutions based on quenched disorder realizations. When the disorder is described by Markov mixing statistics, such comparisons have been attempted so far only for one-dimensional geometries, of the rod or slab type. In this work we extend these results to Markov media in two-dimensional (extruded) and three-dimensional geometries, by revisiting the classical set of benchmark configurations originally proposed by Adams, Larsen and Pomraning and extended by Brantley. In particular, we examine the discrepancies between CLS and reference solutions for scalar particle flux and transmission/reflection coefficients as a function of the material properties of the benchmark specifications and of the system dimensionality.« less

Jet behaviors and ejection mode recognition of electrohydrodynamic direct-write

NASA Astrophysics Data System (ADS)

Zheng, Jianyi; Zhang, Kai; Jiang, Jiaxin; Wang, Xiang; Li, Wenwang; Liu, Yifang; Liu, Juan; Zheng, Gaofeng

2018-01-01

By introducing image recognition and micro-current testing, jet behavior research was conducted, in which the real-time recognition of ejection mode was realized. To study the factors influencing ejection modes and the current variation trends under different modes, an Electrohydrodynamic Direct-Write (EDW) system with functions of current detection and ejection mode recognition was firstly built. Then a program was developed to recognize the jet modes. As the voltage applied to the metal tip increased, four jet ejection modes in EDW occurred: droplet ejection mode, Taylor cone ejection mode, retractive ejection mode and forked ejection mode. In this work, the corresponding relationship between the ejection modes and the effect on fiber deposition as well as current was studied. The real-time identification of ejection mode and detection of electrospinning current was realized. The results in this paper are contributed to enhancing the ejection stability, providing a good technical basis to produce continuous uniform nanofibers controllably.

Higher-speed coronal mass ejections and their geoeffectiveness

NASA Astrophysics Data System (ADS)

Singh, A. K.; Bhargawa, Asheesh; Tonk, Apeksha

2018-06-01

We have attempted to examine the ability of coronal mass ejections to cause geoeffectiveness. To that end, we have investigated total 571 cases of higher-speed (> 1000 km/s) coronal mass ejection events observed during the years 1996-2012. On the basis of angular width (W) of observance, events of coronal mass ejection were further classified as front-side or halo coronal mass ejections (W = 360°); back-side halo coronal mass ejections (W = 360°); partial halo (120°< W < 360°) and non-halo (W < 120°). From further analysis, we found that front halo coronal mass ejections were much faster and more geoeffective in comparison of partial halo and non-halo coronal mass ejections. We also inferred that the front-sided halo coronal mass ejections were 67.1% geoeffective while geoeffectiveness of partial halo coronal mass ejections and non-halo coronal mass ejections were found to be 44.2% and 56.6% respectively. During the same period of observation, 43% of back-sided CMEs showed geoeffectiveness. We have also investigated some events of coronal mass ejections having speed > 2500 km/s as a case study. We have concluded that mere speed of coronal mass ejection and their association with solar flares or solar activity were not mere criterion for producing geoeffectiveness but angular width of coronal mass ejections and their originating position also played a key role.

ACHILLES: Heat Transfer in PWR Core During LOCA Reflood Phase

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

2013-11-01

1. NAME AND TITLE OF DATA LIBRARY ACHILLES -Heat Transfer in PWR Core During LOCA Reflood Phase. 2. NAME AND TITLE OF DATA RETRIEVAL PROGRAMS N/A 3. CONTRIBUTOR AEA Technology, Winfrith Technology Centre, Dorchester DT2 8DH United Kingdom through the OECD Nuclear Energy Agency Data Bank, Issy-les-Moulineaux, France. 4. DESCRIPTION OF TEST FACILITY The most important features of the Achilles rig were the shroud vessel, which contained the test section, and the downcomer. These may be thought of as representing the core barrel and the annular downcomer in the reactor pressure vessel. The test section comprises a cluster of 69more » rods in a square array within a circular shroud vessel. The rod diameter and pitch (9.5 mm and 12.6 mm) were typical of PWR dimensions. The internal diameter of the shroud vessel was 128 mm. Each rod was electrically heated over a length of 3.66 m, which is typical of the nuclear heated length in a PWR fuel rod, and each contained 6 internal thermocouples. These were arranged in one of 8 groupings which concentrated the thermocouples in different axial zones. The spacer grids were at prototypic PWR locations. Each grid had two thermocouples attached to its trailing edge at radial locations. The axial power profile along the rods was an 11 step approximation to a "chopped cosine". The shroud vessel had 5 heating zones whose power could be independently controlled. 5. DESCRIPTION OF TESTS The Achilles experiments investigated the heat transfer in the core of a Pressurized Water Reactor during the re-flood phase of a postulated large break loss of coolant accident. The results provided data to validate codes and to improve modeling. Different types of experiments were carried out which included single phase cooling, re-flood under low flow conditions, level swell and re-flood under high flow conditions. Three series of experiments were performed. The first and the third used the same test section but the second used another test section, similar in all respects except that it contained a partial blockage formed by attaching sleeves (or "balloons") to some of the rods. 6. SOURCE AND SCOPE OF DATA Phenomena Tested - Heat transfer in the core of a PWR during a re-flood phase of postulated large break LOCA. Test Designation - Achilles Rig. The programme includes the following types of experiments: - on an unballooned cluster: -- single phase air flow -- low pressure level swell -- low flooding rate re-flood -- high flooding rate re-flood - on a ballooned cluster containing 80% blockage formed by 16 balloon sleeves -- single phase air flow -- low flooding rate re-flood 7. DISCUSSION OF THE DATA RETRIEVAL PROGRAM N/A 8. DATA FORMAT AND COMPUTER Many Computers (M00019MNYCP00). 9. TYPICAL RUNNING TIME N/A 11. CONTENTS OF LIBRARY The ACHILLES package contains test data and associated data processing software as well as the documentation listed above. 12. DATE OF ABSTRACT November 2013. KEYWORDS: DATABASES, BENCHMARKS, HEAT TRANSFER, LOSS-OF-COLLANT ACCIDENT, PWR REACTORS, REFLOODING« less

Blank fire configuration for automatic pistol

DOEpatents

Teague, Tommy L.

1990-01-01

A pistol configured to fire blank cartridges includes a modified barrel with a breech portion connected to an aligned inner sleeve. Around the inner sleeve, there is disposed an outer sleeve having a vent therein through which the cartridge discharges. The breech portion is connected to a barrel anchor to move backward in a slight arc when the pistol is fired. A spring retention rod projects from the barrel anchor and receives a shortened recoil spring therearound which recoil spring has one end abutting a stop on the barrel anchor and the other end in abutment with the end of a spring retaining cup. The spring retaining cup is engaged by a flange projecting from a slide so that when the pistol is fired, the slide moves rearwardly against the compression of the spring to eject the spent cartridge and then moves forwardly under the urging of the spring to load a fresh cartridge into the breech portion. The spring then returns all of the slidable elements to their initial position so that the pistol may again be fired.

Aircrew ejection experience: questionnaire responses from 20 survivors.

PubMed

Taneja, Narinder; Pinto, Leslie J; Dogra, Manmohan

2005-07-01

Published studies on ejection have focused predominantly on the injuries sustained by aircrew and discussed their preventive measures from an aeromedical perspective. However, studies have not discussed aircrew experiences related to ejection or how they would like to advise other aircrew to successfully handle ejection as an event. Such information can assist in designing realistic indoctrination and training programs. This study was conducted to fill gaps in our understanding of aircrew perspectives of successful ejections. Aircrew reporting to the Institute of Aerospace Medicine (IAM), Indian Air Force, for post-ejection evaluation during the period of May 2003 to January 2005 completed a questionnaire that was designed for the study. A total of 20 aircrew completed this questionnaire. The mean age of the aircrew was 30.25 +/- 4.45 yr. Most of them had logged more than 500 flying hours. Some aircrew described their initial moments of ejection as "blacked out," "dazed, yet conscious," or as "a shock that gradually decreased." Practicing ejection drills on the ground, being prepared at all times, making a timely decision to eject, and assuming correct posture were identified as the most important factors for success. Descriptions of ejection as an event suggest intense emotional arousal could occur following ejection. This study provides first hand inputs into the psychological processes accompanying ejections. Such information could be very useful in understanding the critical factors that influence successful ejection.

Report of ejections in the Spanish Air Force, 1979-1995: an epidemiological and comparative study.

PubMed

Moreno Vázquez, J M; Durán Tejeda, M R; García Alcón, J L

1999-07-01

Ejection seats have saved many lives with more than 80% of pilots having survived an ejection. Nevertheless, ejection injuries are seen in all modern air forces. An epidemiological study has been carried out on the 48 ejections made by the Spanish Air Force (SpAF) from 1979-1995. From data facilitated by the Flight Safety Section of the SpAF Staff, by the Flight Safety Section of Squadrons, and from personal reports of pilots who survived ejections a form was created. Relationships between data concerning aeronautical parameters, pilot data and injuries have been found, and a comparative study was made between these results and data shown by air forces of other countries. Of 48 pilots who ejected, 7 died, 25 had severe injuries, 11 had minor injuries and 5 had no injuries. The reason for the ejections included 35 cases of technical failure, and 13 cases of human error. Of 43 surviving pilots, 23 were injured only at the egress phase, 1 1 only at landing, and 9 cases at both moments. None of the five pilots who ejected outside the ejection envelope were able to adopt the correct position. However, of 43 pilots who ejected within the envelope, 19 were seated in good position. Of 13 pilots who maintained control of the airplane, 9 were able to adopt a correct position. Of 35 pilots who effected the ejection without control of the aircraft, 25 were not able to achieve a correct seated position. The pilot position in the ejection seat, plane control, ejection inside the envelope, the pilot's training in how to assume the necessary body position at both egress and landing phases are determining factors for successful ejections.

The influence of occupant anthropometry and seat position on ejection risk in a rollover.

PubMed

Atkinson, Theresa; Fras, Andrew; Telehowski, Paul

2010-08-01

During rollover crashes, ejection increases an occupant's risk of severe to fatal injury as compared to risks for those retained in the vehicle. The current study examined whether occupant anthropometry might influence ejection risk. Factors such as restraint use/disuse, seating position, vehicle type, and roll direction were also considered in the analysis. The current study examined occupant ejections in 10 years of National Automotive Sampling System (NASS) single-event rollovers of passenger vehicles and light trucks. Statistical analysis of unweighted and weighted ejection data was carried out. No statistically significant differences in ejection rates were found based on occupant height, age, or body mass index. Drivers were ejected significantly more frequently than other occupants: 62 percent of unrestrained drivers were ejected vs. 51 percent unrestrained right front occupants. Second row unrestrained occupants were ejected at rates similar to right front-seated occupants. There were no significant differences in ejection rates for near- vs. far-side occupants. These data suggest that assessment of ejection prevention systems using either a 50th or 5th percentile adult anthropomorphic test dummy (ATD) might provide a reasonable measure of system function for a broad range of occupants. They also support the development of ejection mitigation technologies that extend beyond the first row to protect occupants in rear seat positions. Future studies should consider potential interaction effects (i.e., occupant size and vehicle dimensions) and the influence of occupant size on ejection risk in non-single-event rollovers.

Deployment history and design considerations for space reactor power systems

NASA Astrophysics Data System (ADS)

El-Genk, Mohamed S.

2009-05-01

The history of the deployment of nuclear reactors in Earth orbits is reviewed with emphases on lessons learned and the operation and safety experiences. The former Soviet Union's "BUK" power systems, with SiGe thermoelectric conversion and fast neutron energy spectrum reactors, powered a total of 31 Radar Ocean Reconnaissance Satellites (RORSATs) from 1970 to 1988 in 260 km orbit. Two of the former Soviet Union's TOPAZ reactors, with in-core thermionic conversion and epithermal neutron energy spectrum, powered two Cosmos missions launched in 1987 in ˜800 km orbit. The US' SNAP-10A system, with SiGe energy conversion and a thermal neutron energy spectrum reactor, was launched in 1965 in 1300 km orbit. The three reactor systems used liquid NaK-78 coolant, stainless steel structure and highly enriched uranium fuel (90-96 wt%) and operated at a reactor exit temperature of 833-973 K. The BUK reactors used U-Mo fuel rods, TOPAZ used UO 2 fuel rods and four ZrH moderator disks, and the SNAP-10A used moderated U-ZrH fuel rods. These low power space reactor systems were designed for short missions (˜0.5 kW e and ˜1 year for SNAP-10A, <3.0 kW e and <6 months for BUK, and ˜5.5 kW e and up to 1 year for TOPAZ). The deactivated BUK reactors at the end of mission, which varied in duration from a few hours to ˜4.5 months, were boosted into ˜800 km storage orbit with a decay life of more than 600 year. The ejection of the last 16 BUK reactor fuel cores caused significant contamination of Earth orbits with NaK droplets that varied in sizes from a few microns to 5 cm. Power systems to enhance or enable future interplanetary exploration, in-situ resources utilization on Mars and the Moon, and civilian missions in 1000-3000 km orbits would generate significantly more power of 10's to 100's kW e for 5-10 years, or even longer. A number of design options to enhance the operation reliability and safety of these high power space reactor power systems are presented and discussed.

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.

Role of osmotic and hydrostatic pressures in bacteriophage genome ejection

NASA Astrophysics Data System (ADS)

Lemay, Serge G.; Panja, Debabrata; Molineux, Ian J.

2013-02-01

A critical step in the bacteriophage life cycle is genome ejection into host bacteria. The ejection process for double-stranded DNA phages has been studied thoroughly in vitro, where after triggering with the cellular receptor the genome ejects into a buffer. The experimental data have been interpreted in terms of the decrease in free energy of the densely packed DNA associated with genome ejection. Here we detail a simple model of genome ejection in terms of the hydrostatic and osmotic pressures inside the phage, a bacterium, and a buffer solution or culture medium. We argue that the hydrodynamic flow associated with the water movement from the buffer solution into the phage capsid and further drainage into the bacterial cytoplasm, driven by the osmotic gradient between the bacterial cytoplasm and culture medium, provides an alternative mechanism for phage genome ejection in vivo; the mechanism is perfectly consistent with phage genome ejection in vitro.

Splash detail due to a single grain incident on a granular bed.

PubMed

Tanabe, Takahiro; Shimada, Takashi; Ito, Nobuyasu; Nishimori, Hiraku

2017-02-01

Using the discrete element method, we study the splash processes induced by the impact of a grain on a randomly packed bed. Good correspondence is obtained between our numerical results and the findings of previous experiments for the movement of ejected grains. Furthermore, the distributions of the ejection angle and ejection speed for individual grains vary depending on the relative timing at which the grains are ejected after the initial impact. Obvious differences are observed between the distributions of grains ejected during the earlier and later splash periods: the form of the vertical ejection-speed distribution varies from a power-law form to a lognormal form with time; this difference may determine grain trajectory after ejection.

Stress analysis in a pedicle screw fixation system with flexible rods in the lumbar spine.

PubMed

Kim, Kyungsoo; Park, Won Man; Kim, Yoon Hyuk; Lee, SuKyoung

2010-01-01

Breakage of screws has been one of the most common complications in spinal fixation systems. However, no studies have examined the breakage risk of pedicle screw fixation systems that use flexible rods, even though flexible rods are currently being used for dynamic stabilization. In this study, the risk of breakage of screws for the rods with various flexibilities in pedicle screw fixation systems is investigated by calculating the von Mises stress as a breakage risk factor using finite element analysis. Three-dimensional finite element models of the lumbar spine with posterior one-level spinal fixations at L4-L5 using four types of rod (a straight rod, a 4 mm spring rod, a 3 mm spring rod, and a 2 mm spring rod) were developed. The von Mises stresses in both the pedicle screws and the rods were analysed under flexion, extension, lateral bending, and torsion moments of 10 Nm with a follower load of 400 N. The maximum von Mises stress, which was concentrated on the neck region of the pedicle screw, decreased as the flexibility of the rod increased. However, the ratio of the maximum stress in the rod to the yield stress increased substantially when a highly flexible rod was used. Thus, the level of rod flexibility should be considered carefully when using flexible rods for dynamic stabilization because the intersegmental motion facilitated by the flexible rod results in rod breakage.

Modeling and simulation performance of sucker rod beam pump

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

Aditsania, Annisa, E-mail: annisaaditsania@gmail.com; Rahmawati, Silvy Dewi, E-mail: silvyarahmawati@gmail.com; Sukarno, Pudjo, E-mail: psukarno@gmail.com

2015-09-30

Artificial lift is a mechanism to lift hydrocarbon, generally petroleum, from a well to surface. This is used in the case that the natural pressure from the reservoir has significantly decreased. Sucker rod beam pumping is a method of artificial lift. Sucker rod beam pump is modeled in this research as a function of geometry of the surface part, the size of sucker rod string, and fluid properties. Besides its length, sucker rod string also classified into tapered and un-tapered. At the beginning of this research, for easy modeling, the sucker rod string was assumed as un-tapered. The assumption provedmore » non-realistic to use. Therefore, the tapered sucker rod string modeling needs building. The numerical solution of this sucker rod beam pump model is computed using finite difference method. The numerical result shows that the peak of polished rod load for sucker rod beam pump unit C-456-D-256-120, for non-tapered sucker rod string is 38504.2 lb, while for tapered rod string is 25723.3 lb. For that reason, to avoid the sucker rod string breaks due to the overload, the use of tapered sucker rod beam string is suggested in this research.« less

Air pollution and heart failure: Relationship with the ejection fraction

PubMed Central

Dominguez-Rodriguez, Alberto; Abreu-Afonso, Javier; Rodríguez, Sergio; Juarez-Prera, Ruben A; Arroyo-Ucar, Eduardo; Gonzalez, Yenny; Abreu-Gonzalez, Pedro; Avanzas, Pablo

2013-01-01

AIM: To study whether the concentrations of particulate matter in ambient air are associated with hospital admission due to heart failure in patients with heart failure with preserved ejection fraction and reduced ejection fraction. METHODS: We studied 353 consecutive patients admitted into a tertiary care hospital with a diagnosis of heart failure. Patients with ejection fraction of ≥ 45% were classified as having heart failure with preserved ejection fraction and those with an ejection fraction of < 45% were classified as having heart failure with reduced ejection fraction. We determined the average concentrations of different sizes of particulate matter (< 10, < 2.5, and < 1 μm) and the concentrations of gaseous pollutants (carbon monoxide, sulphur dioxide, nitrogen dioxide and ozone) from 1 d up to 7 d prior to admission. RESULTS: The heart failure with preserved ejection fraction population was exposed to higher nitrogen dioxide concentrations compared to the heart failure with reduced ejection fraction population (12.95 ± 8.22 μg/m3 vs 4.50 ± 2.34 μg/m3, P < 0.0001). Multivariate analysis showed that nitrogen dioxide was a significant predictor of heart failure with preserved ejection fraction (odds ratio ranging from (1.403, 95%CI: 1.003-2.007, P = 0.04) to (1.669, 95%CI: 1.043-2.671, P = 0.03). CONCLUSION: This study demonstrates that short-term nitrogen dioxide exposure is independently associated with admission in the heart failure with preserved ejection fraction population. PMID:23538391

Space-time evolution of ejected plasma for the triggering of gas switch

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

Liu, Shanhong, E-mail: liushanhong108098@163.com; Liu, Xuandong; Shen, Xi

2016-06-15

Ejected plasma has been widely applied to the discharge process of gas spark switches as a trigger technology, and the development process of ejected plasma has a direct and important effect on the discharge characteristics of gas switches. In this paper, both the injection characteristics and space-time evolution of ejected plasma for the triggering of gas spark switch with different stored energies, pulse polarities, and pressures are studied. The discharge characteristics and breakdown process of a gas switch ignited by ejected plasma under different working coefficients are also discussed briefly. The results show that stored energy has significant influence onmore » the characteristics of ejected plasma. With the increase of stored energy, the propulsion mode of ejected plasma in the axial direction transforms from “plasmoid” to “plasma flow,” and the distribution of the ejected plasma goes through “cloud,” “core-cloud,” and “branch” in sequence. The velocity of ejected plasma under negative pulse polarity is obviously higher than that under positive pulse polarity, especially at the very beginning time. The radial dimensions of ejected plasma under two kinds of pulse polarities follow the similar varying pattern over time, which increase first and then decrease, assuming an inverted “U”-shaped curve. With the increase of pressure, the velocity of ejected plasma significantly decreases and the “branch” channels droop earlier. Applying the ejected plasma to the triggering of a gas switch, the switch can be triggered reliably in a much wide working coefficient range of 10%–90%. With the increase of working coefficient, the breakdown process of the switch translates from slow working mode to fast working mode, and the delay time reduces from tens of μs to hundreds of ns.« less

Retinal instrument

DOEpatents

Britton, Charles L; D& #x27; Urso, Brian R; Chaum, Edward; Simpson, John T; Baba, Justin S; Ericson, M. Nance; Warmack, Robert J

2013-04-23

In one embodiment, the present invention provides a method of removing scar tissue from an eye that includes inserting a device including an array of micro-rods into an eye, wherein at least one glass micro-rod of the array of glass micro-rods includes a sharp feature; contacting a scar tissue with the array of micro-rods; and removing the array of micro-rods and the scar tissue from the eye. In another embodiment, the present invention provides a medical device for engaging a tissue including and an array of glass micro-rods, wherein at least one glass micro-rod of the array of glass micro-rods includes a sharp feature opposite a base of the array of glass micro-rods that is connected to the cannula, wherein the sharp feature of the at least one micro-rod is angled from a plane that is normal to a face of the base of the array of glass micro-rods.

Influence of implant rod curvature on sagittal correction of scoliosis deformity.

PubMed

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

2014-08-01

Deformation of in vivo-implanted rods could alter the scoliosis sagittal correction. To our knowledge, no previous authors have investigated the influence of implanted-rod deformation on the sagittal deformity correction during scoliosis surgery. To analyze the changes of the implant rod's angle of curvature during surgery and establish its influence on sagittal correction of scoliosis deformity. A retrospective analysis of the preoperative and postoperative implant rod geometry and angle of curvature was conducted. Twenty adolescent idiopathic scoliosis patients underwent surgery. Average age at the time of operation was 14 years. The preoperative and postoperative implant rod angle of curvature expressed in degrees was obtained for each patient. Two implant rods were attached to the concave and convex side of the spinal deformity. The preoperative implant rod geometry was measured before surgical implantation. The postoperative implant rod geometry after surgery was measured by computed tomography. The implant rod angle of curvature at the sagittal plane was obtained from the implant rod geometry. The angle of curvature between the implant rod extreme ends was measured before implantation and after surgery. The sagittal curvature between the corresponding spinal levels of healthy adolescents obtained by previous studies was compared with the implant rod angle of curvature to evaluate the sagittal curve correction. The difference between the postoperative implant rod angle of curvature and normal spine sagittal curvature of the corresponding instrumented level was used to evaluate over or under correction of the sagittal deformity. The implant rods at the concave side of deformity of all patients were significantly deformed after surgery. The average degree of rod deformation Δθ at the concave and convex sides was 15.8° and 1.6°, respectively. The average preoperative and postoperative implant rod angle of curvature at the concave side was 33.6° and 17.8°, respectively. The average preoperative and postoperative implant rod angle of curvature at the convex side was 25.5° and 23.9°, respectively. A significant relationship was found between the degree of rod deformation and preoperative implant rod angle of curvature (r=0.60, p<.005). The implant rods at the convex side of all patients did not have significant deformation. The results indicate that the postoperative sagittal outcome could be predicted from the initial rod shape. Changes in implant rod angle of curvature may lead to over- or undercorrection of the sagittal curve. Rod deformation at the concave side suggests that corrective forces acting on that side are greater than the convex side. Copyright © 2014 Elsevier Inc. All rights reserved.

Nuclear reactor remote disconnect control rod coupling indicator

DOEpatents

Vuckovich, Michael

1977-01-01

A coupling indicator for use with nuclear reactor control rod assemblies which have remotely disengageable couplings between the control rod and the control rod drive shaft. The coupling indicator indicates whether the control rod and the control rod drive shaft are engaged or disengaged. A resistive network, utilizing magnetic reed switches, senses the position of the control rod drive mechanism lead screw and the control rod position indicating tube, and the relative position of these two elements with respect to each other is compared to determine whether the coupling is engaged or disengaged.

Online collaboration and model sharing in volcanology via VHub.org

NASA Astrophysics Data System (ADS)

Valentine, G.; Patra, A. K.; Bajo, J. V.; Bursik, M. I.; Calder, E.; Carn, S. A.; Charbonnier, S. J.; Connor, C.; Connor, L.; Courtland, L. M.; Gallo, S.; Jones, M.; Palma Lizana, J. L.; Moore-Russo, D.; Renschler, C. S.; Rose, W. I.

2013-12-01

VHub (short for VolcanoHub, and accessible at vhub.org) is an online platform for barrier free access to high end modeling and simulation and collaboration in research and training related to volcanoes, the hazards they pose, and risk mitigation. The underlying concept is to provide a platform, building upon the successful HUBzero software infrastructure (hubzero.org), that enables workers to collaborate online and to easily share information, modeling and analysis tools, and educational materials with colleagues around the globe. Collaboration occurs around several different points: (1) modeling and simulation; (2) data sharing; (3) education and training; (4) volcano observatories; and (5) project-specific groups. VHub promotes modeling and simulation in two ways: (1) some models can be implemented on VHub for online execution. VHub can provide a central warehouse for such models that should result in broader dissemination. VHub also provides a platform that supports the more complex CFD models by enabling the sharing of code development and problem-solving knowledge, benchmarking datasets, and the development of validation exercises. VHub also provides a platform for sharing of data and datasets. The VHub development team is implementing the iRODS data sharing middleware (see irods.org). iRODS allows a researcher to access data that are located at participating data sources around the world (a cloud of data) as if the data were housed in a single virtual database. Projects associated with VHub are also going to introduce the use of data driven workflow tools to support the use of multistage analysis processes where computing and data are integrated for model validation, hazard analysis etc. Audio-video recordings of seminars, PowerPoint slide sets, and educational simulations are all items that can be placed onto VHub for use by the community or by selected collaborators. An important point is that the manager of a given educational resource (or any other resource, such as a dataset or a model) can control the privacy of that resource, ranging from private (only accessible by, and known to, specific collaborators) to completely public. VHub is a very useful platform for project-specific collaborations. With a group site on VHub collaborators share documents, datasets, maps, and have ongoing discussions using the discussion board function. VHub is funded by the U.S. National Science Foundation, and is participating in development of larger earth-science cyberinfrastructure initiatives (EarthCube), as well as supporting efforts such as the Global Volcano Model. Emerging VHub-facilitated efforts include model benchmarking, collaborative code development, and growth in online modeling tools.

Photospheric magnetic field of an eroded-by-solar-wind coronal mass ejection

NASA Astrophysics Data System (ADS)

Palacios, J.; Cid, C.; Saiz, E.; Guerrero, A.

2017-10-01

We have investigated the case of a coronal mass ejection that was eroded by the fast wind of a coronal hole in the interplanetary medium. When a solar ejection takes place close to a coronal hole, the flux rope magnetic topology of the coronal mass ejection (CME) may become misshapen at 1 AU as a result of the interaction. Detailed analysis of this event reveals erosion of the interplanetary coronal mass ejection (ICME) magnetic field. In this communication, we study the photospheric magnetic roots of the coronal hole and the coronal mass ejection area with HMI/SDO magnetograms to define their magnetic characteristics.

Bacteriophage T5 DNA ejection under pressure.

PubMed

Leforestier, A; Brasilès, S; de Frutos, M; Raspaud, E; Letellier, L; Tavares, P; Livolant, F

2008-12-19

The transfer of the bacteriophage genome from the capsid into the host cell is a key step of the infectious process. In bacteriophage T5, DNA ejection can be triggered in vitro by simple binding of the phage to its purified Escherichia coli receptor FhuA. Using electrophoresis and cryo-electron microscopy, we measure the extent of DNA ejection as a function of the external osmotic pressure. In the high pressure range (7-16 atm), the amount of DNA ejected decreases with increasing pressure, as theoretically predicted and observed for lambda and SPP1 bacteriophages. In the low and moderate pressure range (2-7 atm), T5 exhibits an unexpected behavior. Instead of a unique ejected length, multiple populations coexist. Some phages eject their complete genome, whereas others stop at some nonrandom states that do not depend on the applied pressure. We show that contrarily to what is observed for the phages SPP1 and lambda, T5 ejection cannot be explained as resulting from a simple pressure equilibrium between the inside and outside of the capsid. Kinetics parameters and/or structural characteristics of the ejection machinery could play a determinant role in T5 DNA ejection.

Ionic liquids-mediated interactions between nanorods

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

Yu, Zhou; Zhang, Fei; Huang, Jingsong

Surface forces mediated by room-temperature ionic liquids (RTILs) play an essential role in diverse applications including self-assembly, lubrication, and electrochemical energy storage. In this work, using molecular simulations we study the interactions between two nanorods immersed in model RTILs at rod-rod separations where both structural and double layer forces are important. The interaction force between neutral rods oscillates as the two rods approach each other, similar to the classical structural forces. Such oscillatory force originates from the density oscillation of RTILs near each rod and is affected by the packing constraints imposed by the neighboring rods. The oscillation period andmore » decay length of the oscillatory force are mainly dictated by the ion density distribution near isolated nanorods. When charges are introduced on the rods, the interaction force remains short-range and oscillatory, similar to the interactions between planar walls mediated by some protic RTILs reported earlier. Nevertheless, introducing net charges to the rods greatly changes the rod-rod interactions, e.g., by delaying the appearance of the first force trough and increasing the oscillation period and decay length of the interaction force. The oscillation period and decay length of the oscillatory force and free energy are commensurate with those of the space charge density near an isolated, charged rod. The free energy of rod-rod interactions reaches local minima (maxima) at rod-rod separations when the space charges near the two rods interfere constructively (destructively). Here, the insight on the short-range interactions between nanorods in RTILs helps guide the design of novel materials, e.g., crystalline ion gels based on rigid-rod polyanions and RTILs.« less

Ionic liquids-mediated interactions between nanorods

DOE PAGES

Yu, Zhou; Zhang, Fei; Huang, Jingsong; ...

2017-10-06

Surface forces mediated by room-temperature ionic liquids (RTILs) play an essential role in diverse applications including self-assembly, lubrication, and electrochemical energy storage. In this work, using molecular simulations we study the interactions between two nanorods immersed in model RTILs at rod-rod separations where both structural and double layer forces are important. The interaction force between neutral rods oscillates as the two rods approach each other, similar to the classical structural forces. Such oscillatory force originates from the density oscillation of RTILs near each rod and is affected by the packing constraints imposed by the neighboring rods. The oscillation period andmore » decay length of the oscillatory force are mainly dictated by the ion density distribution near isolated nanorods. When charges are introduced on the rods, the interaction force remains short-range and oscillatory, similar to the interactions between planar walls mediated by some protic RTILs reported earlier. Nevertheless, introducing net charges to the rods greatly changes the rod-rod interactions, e.g., by delaying the appearance of the first force trough and increasing the oscillation period and decay length of the interaction force. The oscillation period and decay length of the oscillatory force and free energy are commensurate with those of the space charge density near an isolated, charged rod. The free energy of rod-rod interactions reaches local minima (maxima) at rod-rod separations when the space charges near the two rods interfere constructively (destructively). Here, the insight on the short-range interactions between nanorods in RTILs helps guide the design of novel materials, e.g., crystalline ion gels based on rigid-rod polyanions and RTILs.« less

A universal model for solar eruptions.

PubMed

Wyper, Peter F; Antiochos, Spiro K; DeVore, C Richard

2017-04-26

Magnetically driven eruptions on the Sun, from stellar-scale coronal mass ejections to small-scale coronal X-ray and extreme-ultraviolet jets, have frequently been observed to involve the ejection of the highly stressed magnetic flux of a filament. Theoretically, these two phenomena have been thought to arise through very different mechanisms: coronal mass ejections from an ideal (non-dissipative) process, whereby the energy release does not require a change in the magnetic topology, as in the kink or torus instability; and coronal jets from a resistive process involving magnetic reconnection. However, it was recently concluded from new observations that all coronal jets are driven by filament ejection, just like large mass ejections. This suggests that the two phenomena have physically identical origin and hence that a single mechanism may be responsible, that is, either mass ejections arise from reconnection, or jets arise from an ideal instability. Here we report simulations of a coronal jet driven by filament ejection, whereby a region of highly sheared magnetic field near the solar surface becomes unstable and erupts. The results show that magnetic reconnection causes the energy release via 'magnetic breakout'-a positive-feedback mechanism between filament ejection and reconnection. We conclude that if coronal mass ejections and jets are indeed of physically identical origin (although on different spatial scales) then magnetic reconnection (rather than an ideal process) must also underlie mass ejections, and that magnetic breakout is a universal model for solar eruptions.

Control rod drive

DOEpatents

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.

Factors Associated with Delayed Ejection in Mishaps Between 1993 and 2013.

PubMed

Miles, John E

2015-09-01

The purpose of this investigation was to identify factors associated with Air Force aviators delaying ejection during in-flight emergencies. The investigator reviewed all reports within the Air Force Safety Automated System describing mishaps that resulted in the destruction of Air Force ejection-seat equipped aircraft between 1993 and 2013. Crewmembers were classified as either timely or delayed ejectors based on altitude at onset of emergency, altitude at ejection, and a determination regarding whether or not the aircraft was controlled during the mishap sequence. Univariate analysis and multivariate logistic regression were used to explore the association between delayed ejection and multiple potential risk factors. In total, 366 crewmembers were involved in in-flight emergencies in ejection-seat-equipped aircraft that resulted in the loss of the aircraft; 201 (54.9%) of these crewmembers delayed ejection until their aircraft had descended below recommended minimum ejection altitudes. Multivariate analysis indicated that independent risk factors for delayed ejection included increased crewmember flight hours and a mechanical or human-factors related cause of the emergency versus bird strike or midair collision. This investigation provided quantitative assessments of factors associated with aviators delaying ejection during in-flight emergencies. Increased odds of delay among crewmembers with greater than 1500 total flight hours suggests that complacency and overconfidence may adversely influence the ejection decision to at least as great a degree as inexperience. Increased odds of delay during mechanical and human factors mishaps confirms previously reported hypotheses and reaffirms the importance of targeting these areas to reduce aviator injuries and fatalities.

Morphological Diversity of the Rod Spherule: A Study of Serially Reconstructed Electron Micrographs

PubMed Central

Li, Shuai; Mitchell, Joe; Briggs, Deidrie J.; Young, Jaime K.; Long, Samuel S.; Fuerst, Peter G.

2016-01-01

Purpose Rod spherules are the site of the first synaptic contact in the retina’s rod pathway, linking rods to horizontal and bipolar cells. Rod spherules have been described and characterized through electron micrograph (EM) and other studies, but their morphological diversity related to retinal circuitry and their intracellular structures have not been quantified. Most rod spherules are connected to their soma by an axon, but spherules of rods on the surface of the Mus musculus outer plexiform layer often lack an axon and have a spherule structure that is morphologically distinct from rod spherules connected to their soma by an axon. Retraction of the rod axon and spherule is often observed in disease processes and aging, and the retracted rod spherule superficially resembles rod spherules lacking an axon. We hypothesized that retracted spherules take on an axonless spherule morphology, which may be easier to maintain in a diseased state. To test our hypothesis, we quantified the spatial organization and subcellular structures of rod spherules with and without axons. We then compared them to the retracted spherules in a disease model, mice that overexpress Dscam (Down syndrome cell adhesion molecule), to gain a better understanding of the rod synapse in health and disease. Methods We reconstructed serial EM images of wild type and DscamGoF (gain of function) rod spherules at a resolution of 7 nm in the X-Y axis and 60 nm in the Z axis. Rod spherules with and without axons, and retracted spherules in the DscamGoF retina, were reconstructed. The rod spherule intracellular organelles, the invaginating dendrites of rod bipolar cells and horizontal cell axon tips were also reconstructed for statistical analysis. Results Stereotypical rod (R1) spherules occupy the outer two-thirds of the outer plexiform layer (OPL), where they present as spherical terminals with large mitochondria. This spherule group is highly uniform and composed more than 90% of the rod spherule population. Rod spherules lacking an axon (R2) were also described and characterized. This rod spherule group consists of a specific spatial organization that is strictly located at the apical OPL-facing layer of the Outer Nuclear Layer (ONL). The R2 spherule displays a large bowl-shaped synaptic terminal that hugs the rod soma. Retracted spherules in the DscamGoF retina were also reconstructed to test if they are structurally similar to R2 spherules. The misplaced rod spherules in DscamGoF have a gross morphology that is similar to R2 spherules but have significant disruption in internal synapse organization. Conclusion We described a morphological diversity within Mus musculus rod spherules. This diversity is correlated with rod location in the ONL and contributes to the intracellular differences within spherules. Analysis of the DscamGoF retina indicated that their R2 spherules are not significantly different than wild type R2 spherules, but that their retracted rod spherules have abnormal synaptic organization. PMID:26930660

Morphological Diversity of the Rod Spherule: A Study of Serially Reconstructed Electron Micrographs.

PubMed

Li, Shuai; Mitchell, Joe; Briggs, Deidrie J; Young, Jaime K; Long, Samuel S; Fuerst, Peter G

2016-01-01

Rod spherules are the site of the first synaptic contact in the retina's rod pathway, linking rods to horizontal and bipolar cells. Rod spherules have been described and characterized through electron micrograph (EM) and other studies, but their morphological diversity related to retinal circuitry and their intracellular structures have not been quantified. Most rod spherules are connected to their soma by an axon, but spherules of rods on the surface of the Mus musculus outer plexiform layer often lack an axon and have a spherule structure that is morphologically distinct from rod spherules connected to their soma by an axon. Retraction of the rod axon and spherule is often observed in disease processes and aging, and the retracted rod spherule superficially resembles rod spherules lacking an axon. We hypothesized that retracted spherules take on an axonless spherule morphology, which may be easier to maintain in a diseased state. To test our hypothesis, we quantified the spatial organization and subcellular structures of rod spherules with and without axons. We then compared them to the retracted spherules in a disease model, mice that overexpress Dscam (Down syndrome cell adhesion molecule), to gain a better understanding of the rod synapse in health and disease. We reconstructed serial EM images of wild type and DscamGoF (gain of function) rod spherules at a resolution of 7 nm in the X-Y axis and 60 nm in the Z axis. Rod spherules with and without axons, and retracted spherules in the DscamGoF retina, were reconstructed. The rod spherule intracellular organelles, the invaginating dendrites of rod bipolar cells and horizontal cell axon tips were also reconstructed for statistical analysis. Stereotypical rod (R1) spherules occupy the outer two-thirds of the outer plexiform layer (OPL), where they present as spherical terminals with large mitochondria. This spherule group is highly uniform and composed more than 90% of the rod spherule population. Rod spherules lacking an axon (R2) were also described and characterized. This rod spherule group consists of a specific spatial organization that is strictly located at the apical OPL-facing layer of the Outer Nuclear Layer (ONL). The R2 spherule displays a large bowl-shaped synaptic terminal that hugs the rod soma. Retracted spherules in the DscamGoF retina were also reconstructed to test if they are structurally similar to R2 spherules. The misplaced rod spherules in DscamGoF have a gross morphology that is similar to R2 spherules but have significant disruption in internal synapse organization. We described a morphological diversity within Mus musculus rod spherules. This diversity is correlated with rod location in the ONL and contributes to the intracellular differences within spherules. Analysis of the DscamGoF retina indicated that their R2 spherules are not significantly different than wild type R2 spherules, but that their retracted rod spherules have abnormal synaptic organization.

78 FR 76815 - Steel Threaded Rod From India: Preliminary Affirmative Countervailing Duty Determination and...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-12-19

... DEPARTMENT OF COMMERCE International Trade Administration [C-533-856] Steel Threaded Rod From... exporters of steel threaded rod from India. The period of investigation (``POI'') is January 1, 2012... this investigation is steel threaded rod. Steel threaded rod is certain threaded rod, bar, or studs, of...

Pasta Nucleosynthesis: Molecular dynamics simulations of nuclear statistical equilibrium

NASA Astrophysics Data System (ADS)

Caplan, Matthew; Horowitz, Charles; da Silva Schneider, Andre; Berry, Donald

2014-09-01

We simulate the decompression of cold dense nuclear matter, near the nuclear saturation density, in order to study the role of nuclear pasta in r-process nucleosynthesis in neutron star mergers. Our simulations are performed using a classical molecular dynamics model with 51 200 and 409 600 nucleons, and are run on GPUs. We expand our simulation region to decompress systems from initial densities of 0.080 fm-3 down to 0.00125 fm-3. We study proton fractions of YP = 0.05, 0.10, 0.20, 0.30, and 0.40 at T = 0.5, 0.75, and 1 MeV. We calculate the composition of the resulting systems using a cluster algorithm. This composition is in good agreement with nuclear statistical equilibrium models for temperatures of 0.75 and 1 MeV. However, for proton fractions greater than YP = 0.2 at a temperature of T = 0.5 MeV, the MD simulations produce non-equilibrium results with large rod-like nuclei. Our MD model is valid at higher densities than simple nuclear statistical equilibrium models and may help determine the initial temperatures and proton fractions of matter ejected in mergers.

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

Tamburello, David A.; McWilliams, Anthony J.; Hardy, Bruce J.

Vessel assemblies, heat transfer units for prefabricated vessels, and methods for heat transfer prefabricated vessel are provided. A heat transfer unit includes a central rod, and a plurality of peripheral rods surrounding the central rod and connected to the central rod. The plurality of peripheral rods are movable between a first collapsed position and a second bowed position, wherein in the second bowed position a midpoint of each of the plurality of peripheral rods is spaced from the central rod relative to in the first position. The heat transfer unit further includes a heat transfer element connected to one ofmore » the plurality of peripheral rods.« less

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.

76 FR 78882 - Carbon and Certain Alloy Steel Wire Rod From Mexico: Affirmative Preliminary Determination of...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-12-20

... Steel Wire Rod From Mexico: Affirmative Preliminary Determination of Circumvention of the Antidumping.... SUMMARY: We preliminarily determine that carbon and certain alloy steel wire rod (wire rod) with an actual.... de C.V. (Deacero) is circumventing the antidumping duty order on wire rod from Mexico (Wire Rod Order...

The AGB star nucleosynthesis in the light of the recent {sup 17}O(p,α){sup 14}N and {sup 18}O(p,α){sup 15}N reaction rate determinations

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

Palmerini, S.; Sergi, M. L.; La Cognata, M.

2015-02-24

Presolar grains form in the cold and dusty envelopes of Asymptotic Giant Branch (AGB) stars. These solides, once that have been ejected by stellar winds, come to us as inclusions in meteorites providing invaluable benchmarks and constraints for our knowledge of low temeperature H-burning in stars. The Trojan Horse Method (THM) has been used to investigate the low-energy cross sections of the {sup 17}O(p,α){sup 14}N and {sup 18}O(p,α){sup 15}N reactions. Moreover, the strength of the 65 keV resonance in the {sup 17}O(p,α){sup 14}N reaction, measured by means of the THM, has been used to renormalize the corresponding resonance strength inmore » the {sup 17}O+p radiative capture channel. The new estimates of the reaction rates have been introduced into calculations of AGB star nucleosynthesis and the results have been compared with geochemical analysis of 'presolar' grains to determine their impact on astrophysical environments.« less

369 TFlop/s molecular dynamics simulations on the Roadrunner general-purpose heterogeneous supercomputer

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

Swaminarayan, Sriram; Germann, Timothy C; Kadau, Kai

2008-01-01

The authors present timing and performance numbers for a short-range parallel molecular dynamics (MD) code, SPaSM, that has been rewritten for the heterogeneous Roadrunner supercomputer. Each Roadrunner compute node consists of two AMD Opteron dual-core microprocessors and four PowerXCell 8i enhanced Cell microprocessors, so that there are four MPI ranks per node, each with one Opteron and one Cell. The interatomic forces are computed on the Cells (each with one PPU and eight SPU cores), while the Opterons are used to direct inter-rank communication and perform I/O-heavy periodic analysis, visualization, and checkpointing tasks. The performance measured for our initial implementationmore » of a standard Lennard-Jones pair potential benchmark reached a peak of 369 Tflop/s double-precision floating-point performance on the full Roadrunner system (27.7% of peak), corresponding to 124 MFlop/Watt/s at a price of approximately 3.69 MFlops/dollar. They demonstrate an initial target application, the jetting and ejection of material from a shocked surface.« less

Biomechanical advantages of supplemental accessory and satellite rods with and without interbody cages implantation for the stabilization of pedicle subtraction osteotomy.

PubMed

La Barbera, Luigi; Brayda-Bruno, Marco; Liebsch, Christian; Villa, Tomaso; Luca, Andrea; Galbusera, Fabio; Wilke, Hans-Joachim

2018-05-08

To investigate the effect of anterior interbody cages, accessory and satellite rods usage on primary stability and rod strains for PSO stabilization. Seven human cadaveric spine segments (T12-S1) underwent PSO at L4 with posterior fixation from L2 to S1. In vitro flexibility tests were performed under pure moments in flexion/extension (FE), lateral bending (LB) and axial rotation (AR) to determine the range of motion, while measuring the strains on the primary rods with strain gauge rosettes. Six constructs with 2, 3 and 4 rods, with and without interbody cages implantation adjacent to the PSO site, were compared. All constructs had comparable effects in reducing spine kinematics compared to the intact condition (- 94% in FE and LB; - 80% in AR). Supplementation of 2 rods with lateral accessory rods (4 rods) was the most effective strategy in minimizing primary rod strains, particularly when coupled to cages (p ≤ 0.005; - 50% in FE, - 42% in AR and - 11% in LB); even without cages, the strains were significantly reduced (p ≤ 0.009; - 26%, - 37%, - 9%). The addition of a central satellite rod with laminar hooks (3 rods) effectively reduced rod strains in FE (p ≤ 0.005; - 30%) only in combination with cages. The study supports the current clinical practice providing a strong biomechanical rationale to recommend 4-rod constructs based on accessory rods combined with cages adjacent to PSO site. Although weaker, the usage of accessory rods without cages and of a central satellite rod with hooks in combination with interbody spacers may also be justified. These slides can be retrieved under Electronic Supplementary Material.

Conidial Hydrophobins of Aspergillus fumigatus

PubMed Central

Paris, Sophie; Debeaupuis, Jean-Paul; Crameri, Reto; Carey, Marilyn; Charlès, Franck; Prévost, Marie Christine; Schmitt, Christine; Philippe, Bruno; Latgé, Jean Paul

2003-01-01

The surface of Aspergillus fumigatus conidia, the first structure recognized by the host immune system, is covered by rodlets. We report that this outer cell wall layer contains two hydrophobins, RodAp and RodBp, which are found as highly insoluble complexes. The RODA gene was previously characterized, and ΔrodA conidia do not display a rodlet layer (N. Thau, M. Monod, B. Crestani, C. Rolland, G. Tronchin, J. P. Latgé, and S. Paris, Infect. Immun. 62:4380-4388, 1994). The RODB gene was cloned and disrupted. RodBp was highly homologous to RodAp and different from DewAp of A. nidulans. ΔrodB conidia had a rodlet layer similar to that of the wild-type conidia. Therefore, unlike RodAp, RodBp is not required for rodlet formation. The surface of ΔrodA conidia is granular; in contrast, an amorphous layer is present at the surface of the conidia of the ΔrodA ΔrodB double mutant. These data show that RodBp plays a role in the structure of the conidial cell wall. Moreover, rodletless mutants are more sensitive to killing by alveolar macrophages, suggesting that RodAp or the rodlet structure is involved in the resistance to host cells. PMID:12620846

Surface properties of sprayed and electrodeposited ZnO rod layers

NASA Astrophysics Data System (ADS)

Gromyko, I.; Krunks, M.; Dedova, T.; Katerski, A.; Klauson, D.; Oja Acik, I.

2017-05-01

Herein we present a comparative study on as-deposited, two-month-stored, and heat-treated ZnO rods obtained by spray pyrolysis (SP) at 550 °C, and electrodeposition (ED) at 80 °C. The aim of the study is to establish the reason for different behaviour of wettability and photocatalytic activity (PA) of SP and ED rods. Samples were studied using XPS, SEM, XRD, Raman, contact angle (CA) measurements and photocatalytic oxidation of doxycycline. Wettability and PA are mainly controlled by surface composition rather than by morphology. The relative amount of hydroxyl groups on the surface of as-deposited ED rods is four times higher compared to as-deposited SP rods. Opposite to SP rods, ED rods contain oxygen vacancy defects (Vo). Therefore, as-deposited ED rods are superhydrophilic (CA ∼ 3°) and show highest PA among studied samples, being three times higher compared to SP rods (removing of 75% of doxycycline after 30 min). It was revealed that as-deposited ED rods are inclined to faster contamination. The amount of Cdbnd C groups on the surface of aged ED rods is six times higher compared to aged SP rods. Stored ED samples become hydrophobic (CA ∼ 120°) and PA decreases sharply while SP rods remain hydrophilic (CA ∼ 50°), being more resistive to the contamination.

A New Variety of CMEs: Streamer Puffs from Compact Ejective Flares

NASA Technical Reports Server (NTRS)

Sterling, Alphonse C.; Bemporad, A.; Moore, R. L.; Poletto, G.

2005-01-01

We present SOHO EIT, UVCS and LASCO observations of recurrent (6 --- 8 events per day) narrow (angular widths of about 3 --- 10 degrees) Coronal Mass Ejections (CMEs) which occurred over 2002 November 26--29. The active region where the ejections originate is near the base of a coronal streamer that appears to be unperturbed by the events and keeps stable in time; hence we interpret the observed events as a new class of recursive narrow CMEs that we call "streamer puffs." EIT 304 angstrom (He II) images indicate that the puffs result from compact ejective flares embedded in the streamer, with the ejections from the flares having velocities 100 --- 200 kilometers per second. Most ejections are closely correlated with coronal "jets" seen at 1.7 solar radii in the UVCS data, and a subset of these ejections and jets correspond to streamer puffs observed in LASCO coronagraph images. There are, however, more compact flares and jets than streamer puffs during the observation period, indicating that only a subset of the flare-associated ejections are energetic enough to escape into the heliosphere.

SPERT I DESTRUCTIVE TEST PROGRAM SAFETY ANALYSIS REPORT

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

Spano, A.H.; Miller, R.W.

1962-06-15

The water-moderated core used for destructive experiments is mounted in the Spent I open-type reactor vessel, which has no provision for pressurization or forced coolant flow. The core is an array of highly enriched aluminum clad, plate-type fuel assemblies, using four bladetype, gang-operated control rods. Reactor transients are initiated at ambient temperature by step-insentions of reactivity, using a control rod which can be quickly ejected from the core. Following an initial series of static measurements to determine the basic- reactor properties of the test core, a series of nondestructive, self-limiting power excursion tests was performed, which covered a reactor periodmore » range down to the point where minor fuel plate damage first occurred -approximately for a 10- msec period test. These tests provided power, temperature, and pressure data. Additional kinetic teste in the period region between 10 and 5 msec were completed to explore the region of limited core damage. Fuel plate damage results included plate distortion, cladding cracking, and fuel melting. These exploratory tests were valuable in revealing unexpected changes in the dependence of pressure, temperature, burst energy, and burst shape parameters on reactor period, although the dependence of peak power on reactor period was not significantly changed. An evaluation of hazards involved in conducting the 2- msec test, based on pessimistic assumptions regarding fission product release and weather conditions, indicates that with the procedural controls normally exercised in the conduct of any transient test at Spent and the special controls to be in effect during the destructive test series, no significant hazard to personnel or to the general public will be obtained. All nuclear operation is conducted remotely approximately 1/2 mile from the reactor building. Discussion is also given of the supervision and control of personnel during and after each destructive test, and of the plans for re-entry, cleanup, and restoration of the facility. (auth)« less

Speeds of coronal mass ejections: SMM observations from 1980 and 1984-1989

NASA Technical Reports Server (NTRS)

Hundhausen, A. J.; Burkepile, J. T.; St. Cyr, O. C.

1994-01-01

The speeds of 936 features in 673 coronal mass ejections have been determined from trajectories observed with the Solar Maximum Mission (SMM) coronagraph in 1980 and 1984 to 1989. The distribution of observed speeds has a range (from 5th to 95th percentile) of 35 to 911 km/s; the average and median speeds are 349 and 285 km/s. The speed distributions of some selected classes of mass ejections are significantly different. For example, the speeds of 331 'outer loops' range from 80 to 1042 km/s; the average and median speeds for this class of ejections are 445 and 372 km/s. The speed distributions from each year of SMM observations show significant changes, with the annual average speeds varying from 157 (1984) to 458 km/s (1985). These variations are not simply related to the solar activity cycle; the annual averages from years near the sunspot maxima and minimum are not significantly different. The widths, latitudes, and speeds of mass ejections determined from the SMM observations are only weakly correlated. In particular, mass ejection speeds vary only slightly with the heliographic latitudes of the ejection. High-latitude ejections, which occur well poleward of the active latitudes, have speeds similar to active latitude ejections.

A Universal Model for Solar Eruptions

NASA Technical Reports Server (NTRS)

Wyper, Peter F.; Antiochos, Spiro K.; Devore, C. Richard

2017-01-01

Magnetically driven eruptions on the Sun, from stellar-scale coronal mass ejections1 to small-scale coronal X-ray and extreme-ultraviolet jets, have frequently been observed to involve the ejection of the highly stressed magnetic flux of a filament. Theoretically, these two phenomena have been thought to arise through very different mechanisms: coronal mass ejections from an ideal (non-dissipative) process, whereby the energy release does not require a change in the magnetic topology, as in the kink or torus instability; and coronal jets from a resistive process, involving magnetic reconnection. However, it was recently concluded from new observations that all coronal jets are driven by filament ejection, just like large mass ejections. This suggests that the two phenomena have physically identical origin and hence that a single mechanism may be responsible, that is, either mass ejections arise from reconnection, or jets arise from an ideal instability. Here we report simulations of a coronal jet driven by filament ejection, whereby a region of highly sheared magnetic field near the solar surface becomes unstable and erupts. The results show that magnetic reconnection causes the energy release via 'magnetic breakout', a positive feedback mechanism between filament ejection and reconnection. We conclude that if coronal mass ejections and jets are indeed of physically identical origin (although on different spatial scales) then magnetic reconnection (rather than an ideal process) must also underlie mass ejections, and that magnetic breakout is a universal model for solar eruptions.

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.

Heat transfer unit and method for prefabricated vessel

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

Tamburello, David A.; Kesterson, Matthew R; Hardy, Bruce J.

Vessel assemblies, heat transfer units for prefabricated vessels, and methods for heat transfer prefabricated vessel are provided. A heat transfer unit includes a central rod, and a plurality of peripheral rods surrounding the central rod and connected to the central rod. The plurality of peripheral rods are movable between a first collapsed position and a second bowed position, wherein in the second bowed position a midpoint of each of the plurality of peripheral rods is spaced from the central rod relative to in the first position. The heat transfer unit further includes a heat transfer element connected to one ofmore » the plurality of peripheral rods.« less

Numerical Study of Splash Detail Due to Grain Impact on Granular Bed

NASA Astrophysics Data System (ADS)

Tanabe, Takahiro; Niiya, Hirofumi; Awazu, Akinori; Nishimori, Hiraku

2017-04-01

Massive sediment transport phenomena, such as sand storm and drifting snow, pose a considerable threat to human life. Further, the formation of geomorphological patterns on sand-desert and snowfield surfaces as a result of sediment transport, such as dunes and ripples, is of considerable research interest. Because the major component of the grain entrainment into the air is caused by both the collision and ejection, it is necessary to focus on the collisions between wind-blown grains and surface of sand field along with the resultant ejection grains from the surfaces, which processes are, as a whole, called a splash process. However, because of complexity of jumping grains over the ground surface, detailed measurement is very hard. Therefore, to investigate the splash process, we simulate detailed process of splash caused by 1-grain impact onto a randomly packed granular bed using discrete element method. As a result, we obtained good correspondence between our numerical results and the findings of previous experiments for the movement of ejected grains. Furthermore, the distributions of the ejection angle and the vertical ejection speed for individual grains vary depending on the relative timing at which the grains are ejected after the initial impact. Obvious differences are observed between the distributions of grains ejected during the earlier and later splash periods: the form of the vertical ejection-speed distribution varies from a power-law form to a lognormal form with time, and this difference is related to the grain trajectory after ejection [1]. In addition, we focus on the bulk dynamics inside the granular bed to relate the ejected grains behavior to the force propagations from the first impact to the ejection of each grain. [1] T. Tanabe, T. Shimada, N. Ito, and, H. Nishimori, (submitted)

Noninvasive iPhone Measurement of Left Ventricular Ejection Fraction Using Intrinsic Frequency Methodology.

PubMed

Pahlevan, Niema M; Rinderknecht, Derek G; Tavallali, Peyman; Razavi, Marianne; Tran, Thao T; Fong, Michael W; Kloner, Robert A; Csete, Marie; Gharib, Morteza

2017-07-01

The study is based on previously reported mathematical analysis of arterial waveform that extracts hidden oscillations in the waveform that we called intrinsic frequencies. The goal of this clinical study was to compare the accuracy of left ventricular ejection fraction derived from intrinsic frequencies noninvasively versus left ventricular ejection fraction obtained with cardiac MRI, the most accurate method for left ventricular ejection fraction measurement. After informed consent, in one visit, subjects underwent cardiac MRI examination and noninvasive capture of a carotid waveform using an iPhone camera (The waveform is captured using a custom app that constructs the waveform from skin displacement images during the cardiac cycle.). The waveform was analyzed using intrinsic frequency algorithm. Outpatient MRI facility. Adults able to undergo MRI were referred by local physicians or self-referred in response to local advertisement and included patients with heart failure with reduced ejection fraction diagnosed by a cardiologist. Standard cardiac MRI sequences were used, with periodic breath holding for image stabilization. To minimize motion artifact, the iPhone camera was held in a cradle over the carotid artery during iPhone measurements. Regardless of neck morphology, carotid waveforms were captured in all subjects, within seconds to minutes. Seventy-two patients were studied, ranging in age from 20 to 92 years old. The main endpoint of analysis was left ventricular ejection fraction; overall, the correlation between ejection fraction-iPhone and ejection fraction-MRI was 0.74 (r = 0.74; p < 0.0001; ejection fraction-MRI = 0.93 × [ejection fraction-iPhone] + 1.9). Analysis of carotid waveforms using intrinsic frequency methods can be used to document left ventricular ejection fraction with accuracy comparable with that of MRI. The measurements require no training to perform or interpret, no calibration, and can be repeated at the bedside to generate almost continuous analysis of left ventricular ejection fraction without arterial cannulation.

Contactless heater floating zone refining and crystal growth

NASA Technical Reports Server (NTRS)

Lan, Chung-Wen (Inventor); Kou, Sindo (Inventor)

1993-01-01

Floating zone refining or crystal growth is carried out by providing rapid relative rotation of a feed rod and finish rod while providing heat to the junction between the two rods so that significant forced convection occurs in the melt zone between the two rods. The forced convection distributes heat in the melt zone to allow the rods to be melted through with a much shorter melt zone length than possible utilizing conventional floating zone processes. One of the rods can be rotated with respect to the other, or both rods can be counter-rotated, with typical relative rotational speeds of the rods ranging from 200 revolutions per minute (RPM) to 400 RPM or greater. Zone refining or crystal growth is carried out by traversing the melt zone through the feed rod.

Sizes and locations of coronal mass ejections - SMM observations from 1980 and 1984-1989

NASA Technical Reports Server (NTRS)

Hundhausen, A. J.

1993-01-01

A statistical description of the sizes and locations of 1209 mass ejections observed with the SMM coronagraph/polarimeter in 1980 and 1984-1989 is presented. The average width of the coronal mass ejections detected with this instrument was close to 40 deg in angle for the entire period of SMM observations. No evidence was found for a significant change in mass ejection widths as reported by Howard et al. (1986). There is clear evidence for changes in the latitude distribution of mass ejections over this epoch. Mass ejections occurred over a much wider range of latitudes at the times of high solar activity (1980 and 1989) than at times of low activity (1985-1986).

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)

Stimulus-evoked outer segment changes in rod photoreceptors

NASA Astrophysics Data System (ADS)

Zhao, Xiaohui; Thapa, Damber; Wang, Benquan; Lu, Yiming; Gai, Shaoyan; Yao, Xincheng

2016-06-01

Rod-dominated transient retinal phototropism (TRP) has been recently observed in freshly isolated mouse and frog retinas. Comparative confocal microscopy and optical coherence tomography revealed that the TRP was predominantly elicited from the rod outer segment (OS). However, the biophysical mechanism of rod OS dynamics is still unknown. Mouse and frog retinal slices, which displayed a cross-section of retinal photoreceptors and other functional layers, were used to test the effect of light stimulation on rod OSs. Time-lapse microscopy revealed stimulus-evoked conformational changes of rod OSs. In the center of the stimulated region, the length of the rod OS shrunk, while in the peripheral region, the rod OS swung toward the center region. Our experimental observation and theoretical analysis suggest that the TRP may reflect unbalanced rod disc-shape changes due to localized visible light stimulation.

Stimulus-evoked outer segment changes in rod photoreceptors

PubMed Central

Zhao, Xiaohui; Thapa, Damber; Wang, Benquan; Lu, Yiming; Gai, Shaoyan; Yao, Xincheng

2016-01-01

Abstract. Rod-dominated transient retinal phototropism (TRP) has been recently observed in freshly isolated mouse and frog retinas. Comparative confocal microscopy and optical coherence tomography revealed that the TRP was predominantly elicited from the rod outer segment (OS). However, the biophysical mechanism of rod OS dynamics is still unknown. Mouse and frog retinal slices, which displayed a cross-section of retinal photoreceptors and other functional layers, were used to test the effect of light stimulation on rod OSs. Time-lapse microscopy revealed stimulus-evoked conformational changes of rod OSs. In the center of the stimulated region, the length of the rod OS shrunk, while in the peripheral region, the rod OS swung toward the center region. Our experimental observation and theoretical analysis suggest that the TRP may reflect unbalanced rod disc-shape changes due to localized visible light stimulation. PMID:27334933

Variation in sensitivity, absorption and density of the central rod distribution with eccentricity.

PubMed

Tornow, R P; Stilling, R

1998-01-01

To assess the human rod photopigment distribution and sensitivity with high spatial resolution within the central +/-15 degrees and to compare the results of pigment absorption, sensitivity and rod density distribution (number of rods per square degree). Rod photopigment density distribution was measured with imaging densitometry using a modified Rodenstock scanning laser ophthalmoscope. Dark-adapted sensitivity profiles were measured with green stimuli (17' arc diameter, 1 degrees spacing) using a T ubingen manual perimeter. Sensitivity profiles were plotted on a linear scale and rod photopigment optical density distribution profiles were converted to absorption profiles of the rod photopigment layer. Both the absorption profile of the rod photopigment and the linear sensitivity profile for green stimuli show a minimum at the foveal center and increase steeply with eccentricity. The variation with eccentricity corresponds to the rod density distribution. Rod photopigment absorption profiles, retinal sensitivity profiles, and the rod density distribution are linearly related within the central +/-15 degrees. This is in agreement with theoretical considerations. Both methods, imaging retinal densitometry using a scanning laser ophthalmoscope and dark-adapted perimetry with small green stimuli, are useful for assessing the central rod distribution and sensitivity. However, at present, both methods have limitations. Suggestions for improving the reliability of both methods are given.

Tapered laser rods as a means of minimizing the path length of trapped barrel mode rays

DOEpatents

Beach, Raymond J.; Honea, Eric C.; Payne, Stephen A.; Mercer, Ian; Perry, Michael D.

2005-08-30

By tapering the diameter of a flanged barrel laser rod over its length, the maximum trapped path length of a barrel mode can be dramatically reduced, thereby reducing the ability of the trapped spontaneous emission to negatively impact laser performance through amplified spontaneous emission (ASE). Laser rods with polished barrels and flanged end caps have found increasing application in diode array end-pumped laser systems. The polished barrel of the rod serves to confine diode array pump light within the rod. In systems utilizing an end-pumping geometry and such polished barrel laser rods, the pump light that is introduced into one or both ends of the laser rod, is ducted down the length of the rod via the total internal reflections (TIRs) that occur when the light strikes the rod's barrel. A disadvantage of using polished barrel laser rods is that such rods are very susceptible to barrel mode paths that can trap spontaneous emission over long path lengths. This trapped spontaneous emission can then be amplified through stimulated emission resulting in a situation where the stored energy available to the desired lasing mode is effectively depleted, which then negatively impacts the laser's performance, a result that is effectively reduced by introducing a taper onto the laser rod.

Fuel rod assembly to manifold attachment

DOEpatents

Donck, Harry A.; Veca, Anthony R.; Snyder, Jr., Harold J.

1980-01-01

A fuel element is formed with a plurality of fuel rod assemblies detachably connected to an overhead support with each of the fuel rod assemblies having a gas tight seal with the support to allow internal fission gaseous products to flow without leakage from the fuel rod assemblies into a vent manifold passageway system on the support. The upper ends of the fuel rod assemblies are located at vertically extending openings in the support and upper threaded members are threaded to the fuel rod assemblies to connect the latter to the support. The preferred threaded members are cap nuts having a dome wall encircling an upper threaded end on the fuel rod assembly and having an upper sealing surface for sealing contact with the support. Another and lower seal is achieved by abutting a sealing surface on each fuel rod assembly with the support. A deformable portion on the cap nut locks the latter against inadvertent turning off the fuel rod assembly. Orienting means on the fuel rod and support primarily locates the fuel rods azimuthally for reception of a deforming tool for the cap nut. A cross port in the fuel rod end plug discharges into a sealed annulus within the support, which serves as a circumferential chamber, connecting the manifold gas passageways in the support.

Ejection of small droplet from microplate using focused ultrasound

NASA Astrophysics Data System (ADS)

Tanaka, Hiroki; Mizuno, Yosuke; Nakamura, Kentaro

2017-08-01

We discussed an ultrasonic system for single-droplet ejection from a microplate, which is one of the basic and important procedures in the noncontact handling of droplets in air. In this system, a 1.5 MHz concave transducer located below the microplate is used for chasing the liquid surface through a pulse echo method, and also for the ejection of a 1 µL single droplet by the burst of focused ultrasound. We investigated the relationship between the droplet ejection characteristics, the distance from the transducer to the surface of liquid, the material property, and the excitation condition of the focused ultrasonic transducer. It was verified that the optimal position of the transducer was off the focal point of sound pressure by ±1 mm, because the sound intensity had to be controlled to eject a single droplet. Subsequently, we confirmed experimentally that the ejected droplet volume linearly depended on the surface tension of the liquid, and that the droplet volume and ejection velocity were determined by the Webber number, Reynolds number, and Ohnesolge number. In addition, by optimizing the duration of the burst ultrasound, the droplet volume and ejection velocity were controlled.

The fate of eyewear in aircraft ejections.

PubMed

O'Connell, S R; Markovits, A S

1995-02-01

Ejection from jet aircraft has been exhaustively studied from many perspectives; e.g., causes of ejection, types and causes of ejection injuries, etc. Curiously, no reports exist describing the fate of eyewear in ejections. Many pilots wear required corrective lenses during flight operations, and many wear tinted lenses. What happens to these during ejection? What injuries are a result of the eyewear? What factors can be identified that influence retention of the eyewear and severity of related injury? Do contact lenses provide significant advantages? There were 48 ejections occurring between 1977 and 1990 that involved corrective or tinted lens use that were retrospectively examined using Naval Safety Center records and personal questionnaires. There were five contact lens wearers included. Retention rates were calculated as functions of several variables. Although 37 of 46 lost all lenses, each instance of retention occurred with visor down, oxygen mask on, helmet properly secured, and at lower ejection speeds. Related injuries were minor and occurred in only 20%. The utility and need for enforcement of standard operating procedures (i.e., mask on, helmet secured, and visor down) was clearly demonstrated. Only 19 of 46 clearly met all 3 criteria. Contact lens users were too few to allow meaningful conclusions.

Nest sanitation does not elicit egg ejection in a brown-headed cowbird host.

PubMed

Peer, Brian D

2017-03-01

Most passerine birds practice nest sanitation whereby they remove debris from their nest. Nest sanitation has been posited as a pre-adaptation for egg ejection by hosts of avian brood parasites. However, relatively few North American hosts of the brood parasitic brown-headed cowbird (Molothrus ater) eject cowbird eggs to the detriment of their fitness. In this study, I added either a piece of flagging tape or a pine cone bract scale along with an artificial cowbird egg to nests of the red-winged blackbird (Agelaius phoeniceus) to determine whether the act of nest sanitation would elicit egg ejection. All red-winged blackbirds removed the debris within 24 h, but all individuals also accepted the cowbird eggs and this rate of ejection did not differ from that in nests that only received a cowbird egg. While nest cleaning and egg ejection are similar mechanically, they differ cognitively and egg ejection is not elicited in red-winged blackbirds during the act of removing debris from their nests.

The Moment of Inertia of a Rectangular Rod

NASA Astrophysics Data System (ADS)

Takeuchi, Takao

2007-11-01

Recently an inexpensive setup to obtain the moment of inertia of a rotating system was proposed by Peter E. Banks. An equally simple and inexpensive experiment to obtain the moment of inertia of a uniform rod is proposed in this paper. A rectangular rod with a hole somewhere in the rod was used for this purpose. The moment of inertia of a rectangular rod around the hole location was attempted. The experimental setup is shown in Fig. 1. Various supporting rods, clamps, and rubber stoppers to hold the rectangular rod in place at point p are not shown.

Nuclear reactor control apparatus

DOEpatents

Sridhar, Bettadapur N.

1983-11-01

Nuclear reactor core safety rod release apparatus comprises a control rod having a detent notch in the form of an annular peripheral recess at its upper end, a control rod support tube for raising and lowering the control rod under normal conditions, latches pivotally mounted on the control support tube with free ends thereof normally disposed in the recess in the control rod, and cam means for pivoting the latches out of the recess in the control rod when a scram condition occurs. One embodiment of the invention comprises an additional magnetically-operated latch for releasing the control rod under two different conditions, one involving seismic shock.

Nuclear thermionic converter. [tungsten-thorium oxide rods

NASA Technical Reports Server (NTRS)

Phillips, W. M.; Mondt, J. F. (Inventor)

1977-01-01

Efficient nuclear reactor thermionic converter units are described which can be constructed at low cost and assembled in a reactor which requires a minimum of fuel. Each converter unit utilizes an emitter rod with a fluted exterior, several fuel passages located in the bulges that are formed in the rod between the flutes, and a collector receiving passage formed through the center of the rod. An array of rods is closely packed in an interfitting arrangement, with the bulges of the rods received in the recesses formed between the bulges of other rods, thereby closely packing the nuclear fuel. The rods are constructed of a mixture of tungsten and thorium oxide to provide high power output, high efficiency, high strength, and good machinability.

Lightning discharge protection rod

NASA Technical Reports Server (NTRS)

Bryan, Charles F., Jr. (Inventor)

1987-01-01

A system for protecting an in-air vehicle from damage due to a lighning strike is disclosed. It is an extremely simple device consisting of a sacrificial graphite composite rod, approximately the diameter of a pencil with a length of about five inches. The sacrificial rod is constructed with the graphite fibers running axially within the rod in a manner that best provides a path of conduction axially from the trailing edge of an aircraft to the trailing end of the rod. The sacrificial rod is inserted into an attachment hole machined into trailing edges of aircraft flight surfaces, such as a vertical fin cap and attached with adhesive in a manner not prohibiting the conduction path between the rod and the aircraft. The trailing end of the rod may be tapered for aerodynamic and esthetic requirements. This rod is sacrificial but has the capability to sustain several lightning strikes and still provide protection.

Thermomechanical effects of spine surgery rods composed of different metals and alloys.

PubMed

Noshchenko, Andriy; Patel, Vikas V; Baldini, Todd; Yun, Lu; Lindley, Emily M; Burger, Evalina L

2011-05-15

A basic science study monitoring changes in the curvature of hand contoured commercially pure titanium (CPTi), titanium-aluminum-vanadium alloy (Ti-6Al-4V), and stainless steel (SS) rods maintained at different temperature conditions. To quantify changes in rod-shape at temperatures representative of those used in clinical practice. The shape of implanted rods can be displaced due to thermo-mechanical properties of the materials. Warmer temperatures likely initiate this effect. A study of shape loss characteristics of various rod implants may help eliminate undesirable outcomes caused by shape displacement. Three different types of rods (CPTi, SS, and Ti-6Al-4V) were hand contoured and then maintained in one of following temperature conditions for 35 days: (1) room temperature (20 °C-25 °C) without autoclaving before contouring; (2) preliminary autoclaving (1, 5, 10, 20 cycles) at 135.0 °C ± 2 °C before contouring followed by body temperature (37.2 °C ± 2 °C). Each rod was 5 mm in diameter and 200 mm long. The rods were mounted over graph paper in fixed positions and photographed to measure displacement of the tip as a function of the curvature. RESULTS.: Statistically significant shape loss of the rods manufactured from all the tested materials was found. The hand contoured CPTi rods displayed considerably higher loss of curvature over time than Ti-6Al-4V and SS rods at all tested temperature conditions. Preliminary autoclaving at 135 °C before contouring tended to amplify this effect, in particular 1 cycle of autoclaving. If the number of preliminary autoclaving cycles was higher (5-10), a tendency of decrease of shape loss effect was observed in Ti-6Al-4V and CPTi rods. The shape of the hand contoured CPTi rods was the least stable of the rods across all applied temperature conditions. The SS and Ti-6Al-4V rods were more stable than CPTi rods. Autoclaving before handcontouring tended to increase rods' shape loss.

Systolic versus diastolic heart failure in community practice: clinical features, outcomes, and the use of angiotensin-converting enzyme inhibitors.

PubMed

Philbin, E F; Rocco, T A; Lindenmuth, N W; Ulrich, K; Jenkins, P L

2000-12-01

Among patients with heart failure, there is controversy about whether there are clinical features and laboratory tests that can differentiate patients who have low ejection fractions from those with normal ejection fractions. The usefulness of angiotensin-converting enzyme (ACE) inhibitors among heart failure patients who have normal left ventricular ejection fractions is also not known. From a registry of 2,906 unselected consecutive patients with heart failure who were admitted to 10 acute-care community hospitals during 1995 and 1997, we identified 1291 who had a quantitative measurement of their left ventricular ejection fraction. Patients were separated into three groups based on ejection fraction: < or =0.39 (n = 741, 57%), 0.40 to 0.49 (n = 238, 18%), and > or =0.50 (n = 312, 24%). In-hospital mortality, prescription of ACE inhibitors at discharge, subsequent rehospitalization, quality of life, and survival were measured; survivors were observed for at least 6 months after hospitalization. The mean (+/- SD) age of the sample was 75+/-11 years; the majority (55%) of patients were women. In multivariate models, age >75 years, female sex, weight >72.7 kg, and a valvular etiology for heart failure were associated with an increased probability of having an ejection fraction > or =0.50; a prior history of heart failure, an ischemic or idiopathic cause of heart failure, and radiographic cardiomegaly were associated with a lower probability of having an ejection fraction > or =0.50. Total mortality was lower in patients with an ejection fraction > or =0.50 than in those with an ejection fraction < or =0.39 (odds ratio [OR] = 0.69, 95% confidence interval [CI 0.49 to 0.98, P = 0.04). Among hospital survivors with an ejection fraction of 0.40 to 0.49, the 65% who were prescribed ACE inhibitors at discharge had better mean adjusted quality-of-life scores (7.0 versus 6.2, P = 0.02), and lower adjusted mortality (OR = 0.34, 95% CI: 0.17 to 0.70, P = 0.01) during follow-up than those who were not prescribed ACE inhibitors. Among hospital survivors with an ejection fraction > or =0.50, the 45% who were prescribed ACE inhibitors at discharge had better (lower) adjusted New York Heart Association (NYHA) functional class (2.1 versus 2.4, P = 0.04) although there was no significant improvement in survival. Among patients treated for heart failure in community hospitals, 42% of those whose ejection fraction was measured had a relatively normal systolic function (ejection fraction > or 0.40). The clinical characteristics and mortality of these patients differed from those in patients with low ejection fractions. Among the patients with ejection fractions > or =0.40, the prescription of ACE inhibitors at discharge was associated favorable effects.

Developing rods transplanted into the degenerating retina of Crx-knockout mice exhibit neural activity similar to native photoreceptors

PubMed Central

Homma, Kohei; Okamoto, Satoshi; Mandai, Michiko; Gotoh, Norimoto; Rajasimha, Harsha K.; Chang, Yi-Sheng; Chen, Shan; Li, Wei; Cogliati, Tiziana; Swaroop, Anand; Takahashi, Masayo

2013-01-01

Replacement of dysfunctional or dying photoreceptors offers a promising approach for retinal neurodegenerative diseases, including age-related macular degeneration and retinitis pigmentosa. Several studies have demonstrated the integration and differentiation of developing rod photoreceptors when transplanted in wild type or degenerating retina; however, the physiology and function of the donor cells are not adequately defined. Here, we describe the physiological properties of developing rod photoreceptors that are tagged with GFP driven by the promoter of rod differentiation factor, Nrl. GFP-tagged developing rods show Ca2+ responses and rectifier outward currents that are smaller than those observed in fully developed photoreceptors, suggesting their immature developmental state. These immature rods also exhibit hyperpolarization-activated current (Ih) induced by the activation of hyperpolarization-activated cyclic nucleotide-gated (HCN) channels. When transplanted into the subretinal space of wild type or retinal degeneration mice, GFP-tagged developing rods can integrate into the photoreceptor outer nuclear layer in wild-type mouse retina, and exhibit Ca2+ responses and membrane current comparable to native rod photoreceptors. A proportion of grafted rods develop rhodopsin-positive outer segment-like structures within two weeks after transplantation into the retina of Crx-knockout mice, and produce rectifier outward current and Ih upon membrane depolarization and hyperpolarization. GFP-positive rods derived from induced pluripotent stem (iPS) cells also display similar membrane current Ih as native developing rod photoreceptors, express rod-specific phototransduction genes, and HCN-1 channels. We conclude that Nrl-promoter driven GFP-tagged donor photoreceptors exhibit physiological characteristics of rods and that iPS cell-derived rods in vitro may provide a renewable source for cell replacement therapy. PMID:23495178

Plasma ion-induced molecular ejection on the Galilean satellites - Energies of ejected molecules

NASA Technical Reports Server (NTRS)

Johnson, R. E.; Boring, J. W.; Reimann, C. T.; Barton, L. A.; Sieveka, E. M.; Garrett, J. W.; Farmer, K. R.; Brown, W. L.; Lanzerotti, L. J.

1983-01-01

First measurements of the energy of ejection of molecules from icy surfaces by fast incident ions are presented. Such results are needed in discussions of the Jovian and Saturnian plasma interactions with the icy satellites. In this letter parameters describing the ion-induced ejection and redistribution of molecules on the Galilean satellites are recalculated in light of the new laboratory data.

NEUTRONIC REACTOR CONTROL ROD DRIVE APPARATUS

DOEpatents

Oakes, L.C.; Walker, C.S.

1959-12-15

ABS>A suspension mechanism between a vertically movable nuclear reactor control rod and a rod extension, which also provides information for the operator or an automatic control signal, is described. A spring connects the rod extension to a drive shift. The extension of the spring indicates whether (1) the rod is at rest on the reactor, (2) the rod and extension are suspended, or (3) the extension alone is suspended, the spring controlling a 3-position electrical switch.

Analysis of the causes of recurrence after frontalis suspension using silicone rods for congenital ptosis

PubMed Central

Kim, Chang Yeom; Son, Byeong Jae; Son, Jangyup; Hong, Jongill; Lee, Sang Yeul

2017-01-01

Background Silicone rod is a commonly used synthetic suspension material in frontalis suspension surgery to correct blepharoptosis. The most challenging problem and a decisive drawback of the use of silicone rod is a considerable rate of ptosis recurrence after surgery. We examined patients with recurred ptosis and assessed the physical and micromorphological properties of implanted silicone rods to determine the causative mechanisms of recurred ptosis after frontalis suspension using silicone rod. Methods This is a prospective observational case series of 22 pediatric patients with recurred ptosis after frontalis suspension using silicone rods for congenital ptosis. Implanted silicone rods were observed and removed during the operation for correction of recurred ptosis. The removed silicone rods were physically and micromorphologically evaluated to determine the cause of recurrence. Results Pretarsal fixation positions migrated upward, whereas suprabrow fixation positions migrated downward during ptosis recurrence. The breaking strength of implanted silicone rods was reduced by approximately 50% during 3 years. Cracks, debris, and loss of homogenous structure with disintegration were observed on scanning electron micrographs of implanted silicone rods in patients with recurred ptosis. Preoperative severe degree of ptosis also contributed to recurred ptosis. Conclusions Recurrence of ptosis after frontalis suspension using silicone rod was associated with physical changes of implanted silicone rods, including positional migration, weakened tensile strength, and micromorphological changes in combination with patients’ characteristics. PMID:28207846

Mutations in cell elongation genes mreB, mrdA and mrdB suppress the shape defect of RodZ-deficient cells.

PubMed

Shiomi, Daisuke; Toyoda, Atsushi; Aizu, Tomoyuki; Ejima, Fumio; Fujiyama, Asao; Shini, Tadasu; Kohara, Yuji; Niki, Hironori

2013-03-01

RodZ interacts with MreB and both factors are required to maintain the rod shape of Escherichia coli. The assembly of MreB into filaments regulates the subcellular arrangement of a group of enzymes that synthesizes the peptidoglycan (PG) layer. However, it is still unknown how polymerization of MreB determines the rod shape of bacterial cells. Regulatory factor(s) are likely to be involved in controlling the function and dynamics of MreB. We isolated suppressor mutations to partially recover the rod shape in rodZ deletion mutants and found that some of the suppressor mutations occurred in mreB. All of the mreB mutations were in or in the vicinity of domain IA of MreB. Those mreB mutations changed the property of MreB filaments in vivo. In addition, suppressor mutations were found in the periplasmic regions in PBP2 and RodA, encoded by mrdA and mrdB genes. Similar to MreB and RodZ, PBP2 and RodA are pivotal to the cell wall elongation process. Thus, we found that mutations in domain IA of MreB and in the periplasmic domain of PBP2 and RodA can restore growth and rod shape to ΔrodZ cells, possibly by changing the requirements of MreB in the process. © 2013 Blackwell Publishing Ltd.

Mutations in cell elongation genes mreB, mrdA and mrdB suppress the shape defect of RodZ-deficient cells

PubMed Central

Shiomi, Daisuke; Toyoda, Atsushi; Aizu, Tomoyuki; Ejima, Fumio; Fujiyama, Asao; Shini, Tadasu; Kohara, Yuji; Niki, Hironori

2013-01-01

RodZ interacts with MreB and both factors are required to maintain the rod shape of Escherichia coli. The assembly of MreB into filaments regulates the subcellular arrangement of a group of enzymes that synthesizes the peptidoglycan (PG) layer. However, it is still unknown how polymerization of MreB determines the rod shape of bacterial cells. Regulatory factor(s) are likely to be involved in controlling the function and dynamics of MreB. We isolated suppressor mutations to partially recover the rod shape in rodZ deletion mutants and found that some of the suppressor mutations occurred in mreB. All of the mreB mutations were in or in the vicinity of domain IA of MreB. Those mreB mutations changed the property of MreB filaments in vivo. In addition, suppressor mutations were found in the periplasmic regions in PBP2 and RodA, encoded by mrdA and mrdB genes. Similar to MreB and RodZ, PBP2 and RodA are pivotal to the cell wall elongation process. Thus, we found that mutations in domain IA of MreB and in the periplasmic domain of PBP2 and RodA can restore growth and rod shape to ΔrodZ cells, possibly by changing the requirements of MreB in the process. PMID:23301723

78 FR 79670 - Steel Threaded Rod From Thailand: Preliminary Determination of Sales at Less Than Fair Value and...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-12-31

... DEPARTMENT OF COMMERCE International Trade Administration [A-549-831] Steel Threaded Rod From... ``Department'') preliminarily determines that steel threaded rod from Thailand is being, or is likely to be... Investigation The merchandise covered by this investigation is steel threaded rod. Steel threaded rod is certain...

Measurement of Diffusion in Entangled Rod-Coil Triblock Copolymers

NASA Astrophysics Data System (ADS)

Olsen, B. D.; Wang, M.

2012-02-01

Although rod-coil block copolymers have attracted increasing attention for functional nanomaterials, their dynamics relevant to self-assembly and processing have not been widely investigated. Because the rod and coil blocks have different reptation behavior and persistence lengths, the mechanism by which block copolymers will diffuse is unclear. In order to understand the effect of the rigid block on reptation, tracer diffusion of a coil-rod-coil block copolymer through an entangled coil polymer matrix was experimentally measured. A monodisperse, high molecular weight coil-rod-coil triblock was synthesized using artificial protein engineering to prepare the helical rod and bioconjugaiton of poly(ethylene glycol) coils to produce the final triblock. Diffusion measurements were performed using Forced Rayleigh scattering (FRS), at varying ratios of the rod length to entanglement length, where genetic engineering is used to control the protein rod length and the polymer matrix concentration controls the entanglement length. As compared to PEO homopolymer tracers, the coil-rod-coil triblocks show markedly slower diffusion, suggesting that the mismatch between rod and coil reptation mechanisms results in hindered diffusion of these molecules in the entangled state.

Management of lower-extremity deformities in osteogenesis imperfecta with extensible intramedullary rod technique: a 20-year experience.

PubMed

Luhmann, S J; Sheridan, J J; Capelli, A M; Schoenecker, P L

1998-01-01

Twelve patients (seven boys, five girls) who had osteogenesis imperfecta were treated with an extensible-rod system in 21 femurs and 15 tibias. Indications for use of extensible rods were multiple fractures, long-bone deformity prohibiting bracing and ambulation, and significant remaining linear growth. The average patient age at the time of placement of the extensible rods was 6 + 8 years (range, 2 + 4-10 + 10). Six femurs were treated with overlapping Rush rods; Bailey-Dubow rods were used in the remaining femurs and in all tibias. The average length of follow-up was 5 + 9 years (range, 2 + 0-3 + 2). Preoperatively, four of the 12 patients had never walked; postoperatively, all were ambulators with varying levels of assistance. Fourteen complications occurred, 12 of which required operative revision of the extensible rods. The average time between primary extensible rodding and revision was 5 + 1 years. No complications have occurred to date related to the use of overlapping Rush rods. No growth disturbance resulted from the use of the extensible-rod systems.

Comparative study on neutronics characteristics of a 1500 MWe metal fuel sodium-cooled fast reactor

DOE PAGES

Ohgama, Kazuya; Aliberti, Gerardo; Stauff, Nicolas E.; ...

2017-02-28

Under the cooperative effort of the Civil Nuclear Energy R&D Working Group within the framework of the U.S.-Japan bilateral, Argonne National Laboratory (ANL) and Japan Atomic Energy Agency (JAEA) have been performing benchmark study using Japan Sodium-cooled Fast Reactor (JSFR) design with metal fuel. In this benchmark study, core characteristic parameters at the beginning of cycle were evaluated by the best estimate deterministic and stochastic methodologies of ANL and JAEA. The results obtained by both institutions show a good agreement with less than 200 pcm of discrepancy on the neutron multiplication factor, and less than 3% of discrepancy on themore » sodium void reactivity, Doppler reactivity, and control rod worth. The results by the stochastic and deterministic approaches were compared in each party to investigate impacts of the deterministic approximation and to understand potential variations in the results due to different calculation methodologies employed. From the detailed analysis of methodologies, it was found that the good agreement in multiplication factor from the deterministic calculations comes from the cancellation of the differences on the methodology (0.4%) and nuclear data (0.6%). The different treatment in reflector cross section generation was estimated as the major cause of the discrepancy between the multiplication factors by the JAEA and ANL deterministic methodologies. Impacts of the nuclear data libraries were also investigated using a sensitivity analysis methodology. Furthermore, the differences on the inelastic scattering cross sections of U-238, ν values and fission cross sections of Pu-239 and µ-average of Na-23 are the major contributors to the difference on the multiplication factors.« less

Are Tide Gauges Useful Recorders of Relative Sea-Level Rise in Large Deltaic Settings?

NASA Astrophysics Data System (ADS)

Tornqvist, T. E.; Keogh, M.; Jankowski, K. L.; Fernandes, A. M.

2016-12-01

It has long been recognized that the world's largest deltas that often host major population centers are particularly vulnerable to accelerating rates of relative sea-level rise (RSLR). Traditionally, tide-gauge records are used to obtain quantitative data on rates of RSLR, given that they are perceived to capture the rise of the sea surface as well as land subsidence which is often substantial in deltaic settings. We argue here that tide gauges in such settings often provide ambiguous data because they ultimately measure RSLR with respect to a benchmark that is typically anchored tens of meters below the land surface. This is problematic because the prime target of interest is usually the rate of RSLR with respect to the delta top. We illustrate this problem with newly obtained rod surface elevation table - marker horizon (RSET-MH) data from the Mississippi Delta (n=185) that show that total subsidence is dominated by shallow subsidence in the uppermost 5-10 m. Since benchmarks in this region are anchored at 20 m depth on average, tide-gauge records by definition do not capture this important (and often even dominant) component of total subsidence, and thus underestimate RSLR by a considerable amount. We show how RSET-MH data, combined with GPS and satellite altimetry data, enable us to bypass this problem. Present-day rates of RSLR in the Mississippi Delta are 13±9 mm/yr, considerably higher than numbers reported in recent studies based on tide-gauge analysis. It seems unlikely that this problem is unique to the Mississippi Delta, so we argue that the approach to RSLR measurements in large deltas across the planet needs rethinking.

Untangling ciliary access and enrichment of two rhodopsin-like receptors using quantitative fluorescence microscopy reveals cell-specific sorting pathways.

PubMed

Geneva, Ivayla I; Tan, Han Yen; Calvert, Peter D

2017-02-15

Resolution limitations of optical systems are major obstacles for determining whether proteins are enriched within cell compartments. Here we use an approach to determine the degree of membrane protein ciliary enrichment that quantitatively accounts for the differences in sampling of the ciliary and apical membranes inherent to confocal microscopes. Theory shows that cilia will appear more than threefold brighter than the surrounding apical membrane when the densities of fluorescently labeled proteins are the same, thus providing a benchmark for ciliary enrichment. Using this benchmark, we examined the ciliary enrichment signals of two G protein-coupled receptors (GPCRs)-the somatostatin receptor 3 and rhodopsin. Remarkably, we found that the C-terminal VxPx motif, required for efficient enrichment of rhodopsin within rod photoreceptor sensory cilia, inhibited enrichment of the somatostatin receptor in primary cilia. Similarly, VxPx inhibited primary cilium enrichment of a chimera of rhodopsin and somatostatin receptor 3, where the dual Ax(S/A)xQ ciliary targeting motifs within the third intracellular loop of the somatostatin receptor replaced the third intracellular loop of rhodopsin. Rhodopsin was depleted from primary cilia but gained access, without being enriched, with the dual Ax(S/A)xQ motifs. Ciliary enrichment of these GPCRs thus operates via distinct mechanisms in different cells. © 2017 Geneva et al. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

Monitoring Rates of Subsidence and Relative Sea-Level Rise in Low-Elevation Coastal Zones: A New Approach

NASA Astrophysics Data System (ADS)

Tornqvist, T. E.; Jankowski, K. L.; Fernandes, A. M.; Keogh, M.; Nienhuis, J.

2017-12-01

Low-elevation coastal zones (LECZs) that often host large population centers are particularly vulnerable to accelerating rates of relative sea-level rise (RSLR). Traditionally, tide-gauge records are used to obtain quantitative data on rates of RSLR, given that they are perceived to capture the rise of the sea surface, as well as land subsidence which is often substantial in such settings. We argue here that tide gauges in LECZs often provide ambiguous data because they ultimately measure RSLR with respect to a benchmark that is typically anchored tens of meters deep. This is problematic because the prime target of interest is usually the rate of RSLR with respect to the land surface. We illustrate this problem with newly obtained rod surface elevation table - marker horizon (RSET-MH) data from coastal Louisiana (n = 274) that show that shallow subsidence in the uppermost 5-10 m accounts for 60-85% of total subsidence. Since benchmarks in this region are anchored at 23 m depth on average, tide-gauge records by definition do not capture this important process and thus underestimate RSLR by a considerable amount. We show how RSET-MH data, combined with GPS and satellite altimetry data, enable us to bypass this problem. Rates of RSLR in coastal Louisiana over the past 6-10 years are 12 ± 8 mm/yr, considerably higher than numbers reported in recent studies based on tide-gauge analysis. Subsidence rates, averaged across this region, total about 9 mm/yr. It is likely that the problems with tide-gauge data are not unique to coastal Louisiana, so we suggest that our new approach to RSLR measurements may be useful in LECZs worldwide, with considerable implications for metropolitan areas like New Orleans that are located within such settings.

Comparative study on neutronics characteristics of a 1500 MWe metal fuel sodium-cooled fast reactor

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

Ohgama, Kazuya; Aliberti, Gerardo; Stauff, Nicolas E.

Under the cooperative effort of the Civil Nuclear Energy R&D Working Group within the framework of the U.S.-Japan bilateral, Argonne National Laboratory (ANL) and Japan Atomic Energy Agency (JAEA) have been performing benchmark study using Japan Sodium-cooled Fast Reactor (JSFR) design with metal fuel. In this benchmark study, core characteristic parameters at the beginning of cycle were evaluated by the best estimate deterministic and stochastic methodologies of ANL and JAEA. The results obtained by both institutions show a good agreement with less than 200 pcm of discrepancy on the neutron multiplication factor, and less than 3% of discrepancy on themore » sodium void reactivity, Doppler reactivity, and control rod worth. The results by the stochastic and deterministic approaches were compared in each party to investigate impacts of the deterministic approximation and to understand potential variations in the results due to different calculation methodologies employed. From the detailed analysis of methodologies, it was found that the good agreement in multiplication factor from the deterministic calculations comes from the cancellation of the differences on the methodology (0.4%) and nuclear data (0.6%). The different treatment in reflector cross section generation was estimated as the major cause of the discrepancy between the multiplication factors by the JAEA and ANL deterministic methodologies. Impacts of the nuclear data libraries were also investigated using a sensitivity analysis methodology. Furthermore, the differences on the inelastic scattering cross sections of U-238, ν values and fission cross sections of Pu-239 and µ-average of Na-23 are the major contributors to the difference on the multiplication factors.« less

A test of the nest sanitation hypothesis for the evolution of foreign egg rejection in an avian brood parasite rejecter host species

NASA Astrophysics Data System (ADS)

Luro, Alec B.; Hauber, Mark E.

2017-04-01

Hosts of avian brood parasites have evolved diverse defenses to avoid the costs associated with raising brood parasite nestlings. In egg ejection, the host recognizes and removes foreign eggs laid in its nest. Nest sanitation, a behavior similar in motor pattern to egg ejection, has been proposed repeatedly as a potential pre-adaptation to egg ejection. Here, we separately placed blue 3D-printed, brown-headed cowbird ( Molothrus ater) eggs known to elicit interindividual variation in ejection responses and semi-natural leaves into American robins' ( Turdus migratorius) nests to test proximate predictions that (1) rejecter hosts should sanitize debris from nests more frequently and consistently than accepter hosts and (2) hosts that sanitize their nests of debris prior to the presentation of a foreign egg will be more likely to eject the foreign egg. Egg ejection responses were highly repeatable within individuals yet variable between them, but were not influenced by prior exposure to debris, nor related to sanitation tendencies as a whole, because nearly all individuals sanitized their nests. Additionally, we collected published data for eight different host species to test for a potential positive correlation between sanitation and egg ejection. We found no significant correlation between nest sanitation and egg ejection rates; however, our comparative analysis was limited to a sample size of 8, and we advise that more data from additional species are necessary to properly address interspecific tests of the pre-adaptation hypothesis. In lack of support for the nest sanitation hypothesis, our study suggests that, within individuals, foreign egg ejection is distinct from nest sanitation tendencies, and sanitation and foreign egg ejection may not correlate across species.

A test of the nest sanitation hypothesis for the evolution of foreign egg rejection in an avian brood parasite rejecter host species.

PubMed

Luro, Alec B; Hauber, Mark E

2017-04-01

Hosts of avian brood parasites have evolved diverse defenses to avoid the costs associated with raising brood parasite nestlings. In egg ejection, the host recognizes and removes foreign eggs laid in its nest. Nest sanitation, a behavior similar in motor pattern to egg ejection, has been proposed repeatedly as a potential pre-adaptation to egg ejection. Here, we separately placed blue 3D-printed, brown-headed cowbird (Molothrus ater) eggs known to elicit interindividual variation in ejection responses and semi-natural leaves into American robins' (Turdus migratorius) nests to test proximate predictions that (1) rejecter hosts should sanitize debris from nests more frequently and consistently than accepter hosts and (2) hosts that sanitize their nests of debris prior to the presentation of a foreign egg will be more likely to eject the foreign egg. Egg ejection responses were highly repeatable within individuals yet variable between them, but were not influenced by prior exposure to debris, nor related to sanitation tendencies as a whole, because nearly all individuals sanitized their nests. Additionally, we collected published data for eight different host species to test for a potential positive correlation between sanitation and egg ejection. We found no significant correlation between nest sanitation and egg ejection rates; however, our comparative analysis was limited to a sample size of 8, and we advise that more data from additional species are necessary to properly address interspecific tests of the pre-adaptation hypothesis. In lack of support for the nest sanitation hypothesis, our study suggests that, within individuals, foreign egg ejection is distinct from nest sanitation tendencies, and sanitation and foreign egg ejection may not correlate across species.

Changes in wall teichoic acid during the rod-sphere transition of Bacillus subtilis 168.

PubMed Central

Pollack, J H; Neuhaus, F C

1994-01-01

Wall teichoic acid (WTA) is essential for the growth of Bacillus subtilis 168. To clarify the function of this polymer, the WTAs of strains 168, 104 rodB1, and 113 tagF1 (rodC1) grown at 32 and 42 degrees C were characterized. At the restrictive temperature, the rodB1 and tagF1 (rodC1) mutants undergo a rod-to-sphere transition that is correlated with changes in the WTA content of the cell wall. The amount of WTA decreased 33% in strain 104 rodB1 and 84% in strain 113 tagF1 (rodC1) when they were grown at the restrictive temperature. The extent of alpha-D-glucosylation (0.84) was not affected by growth at the higher temperature in these strains. The degree of D-alanylation decreased from 0.22 to 0.10 in the rodB1 mutant but remained constant (0.12) in the tagF1 (rodC1) mutant at both temperatures. Under these conditions, the degree of D-alanylation in the parent strain decreased from 0.27 to 0.21. The chain lengths of WTA in strains 168 and 104 rodB1 grown at both temperatures were approximately 53 residues, with a range of 45 to 60. In contrast, although the chain length of WTA from the tagF1 (rodC1) mutant at 32 degrees C was similar to that of strains 168 and 104 rodB1, it was approximately eight residues at the restrictive temperature. The results suggested that the rodB1 mutant is partially deficient in completed poly(glycerophosphate) chains. The precise biochemical defect in this mutant remains to be determined. The results for strain 113 tagF1(rodC1) are consistent with the temperature-sensitive defect in the CDP-glycerol:poly(glycerophosphate) glycerophosphotransferase (H. M. Pooley, F.-X. Abellan, and D. Karamata, J. Bacteriol. 174:646-649, 1992). Images PMID:7961496

Outcomes of support rod usage in loop stoma formation.

PubMed

Whiteley, Ian; Russell, Michael; Nassar, Natasha; Gladman, Marc A

2016-06-01

Traditionally, support rods have been used when creating loop stomas in the hope of preventing retraction. However, their effectiveness has not been clearly established. This study aimed to investigate the rate of stoma rod usage and its impact on stoma retraction and complication rates. A prospective cohort of 515 consecutive patients who underwent loop ileostomy/colostomy formation at a tertiary referral colorectal unit in Sydney, Australia were studied. Mortality and unplanned return to theatre rates were calculated. The primary outcome measure of interest was stoma retraction, occurring within 30 days of surgery. Secondary outcome measures included early stoma complications. The 10-year temporal trends for rod usage, stoma retraction, and complications were examined. Mortality occurred in 23 patients (4.1 %) and unplanned return to theatre in 4 patients (0.8 %). Stoma retraction occurred in four patients (0.78 %), all without rods. However, the rate of retraction was similar, irrespective of whether rods were used (P = 0.12). There was a significant decline in the use of rods during the study period (P < 0.001) but this was not associated with an increase in stoma retraction rates. Early complications occurred in 94/432 patients (21.8 %) and were more likely to occur in patients with rods (64/223 versus 30/209 without rods, P < 0.001). Stoma retraction is a rare complication and its incidence is not significantly affected by the use of support rods. Further, complications are common post-operatively, and the rate appears higher when rods are used. The routine use of rods warrants judicious application. WHAT DOES THIS PAPER ADD TO THE LITERATURE?: It remains unclear whether support rods prevent stoma retraction. This study, the largest to date, confirms that stoma retraction is a rare complication and is not significantly affected by the use of rods. Consequently, routine rod usage cannot be recommended, particularly as it is associated with increased stoma complications.

Results of the Simulation of the HTR-Proteus Core 4.2 Using PEBBED-COMBINE: FY10 Report

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

Hans Gougar

2010-07-01

ABSTRACT The Idaho National Laboratory’s deterministic neutronics analysis codes and methods were applied to the computation of the core multiplication factor of the HTR-Proteus pebble bed reactor critical facility. This report is a follow-on to INL/EXT-09-16620 in which the same calculation was performed but using earlier versions of the codes and less developed methods. In that report, results indicated that the cross sections generated using COMBINE-7.0 did not yield satisfactory estimates of keff. It was concluded in the report that the modeling of control rods was not satisfactory. In the past year, improvements to the homogenization capability in COMBINE havemore » enabled the explicit modeling of TRIS particles, pebbles, and heterogeneous core zones including control rod regions using a new multi-scale version of COMBINE in which the 1-dimensional discrete ordinate transport code ANISN has been integrated. The new COMBINE is shown to yield benchmark quality results for pebble unit cell models, the first step in preparing few-group diffusion parameters for core simulations. In this report, the full critical core is modeled once again but with cross sections generated using the capabilities and physics of the improved COMBINE code. The new PEBBED-COMBINE model enables the exact modeling of the pebbles and control rod region along with better approximation to structures in the reflector. Initial results for the core multiplication factor indicate significant improvement in the INL’s tools for modeling the neutronic properties of a pebble bed reactor. Errors on the order of 1.6-2.5% in keff are obtained; a significant improvement over the 5-6% error observed in the earlier This is acceptable for a code system and model in the early stages of development but still too high for a production code. Analysis of a simpler core model indicates an over-prediction of the flux in the low end of the thermal spectrum. Causes of this discrepancy are under investigation. New homogenization techniques and assumptions were used in this analysis and as such, they require further confirmation and validation. Further refinement and review of the complex Proteus core model are likely to reduce the errors even further.« less

Method and means of packaging nuclear fuel rods for handling

DOEpatents

Adam, Milton F.

1979-01-01

Nuclear fuel rods, especially spent nuclear fuel rods that may show physical distortion, are encased within a metallic enclosing structure by forming a tube about the fuel rod. The tube has previously been rolled to form an overlapping tubular structure and then unrolled and coiled about an axis perpendicular to the tube. The fuel rod is inserted into the tube as the rolled tube is removed from a coiled strip and allowed to reassume its tubular shape about the fuel rod. Rollers support the coiled strip in an open position as the coiled strip is uncoiled and allowed to roll about the fuel rod.

Light responses in rods of vitamin A-deprived Xenopus.

PubMed

Solessio, Eduardo; Umino, Yumiko; Cameron, David A; Loew, Ellis; Engbretson, Gustav A; Knox, Barry E; Barlow, Robert B

2009-09-01

Accumulation of free opsin by mutations in rhodopsin or insufficiencies in the visual cycle can lead to retinal degeneration. Free opsin activates phototransduction; however, the link between constitutive activation and retinal degeneration is unclear. In this study, the photoresponses of Xenopus rods rendered constitutively active by vitamin A deprivation were examined. Unlike their mammalian counterparts, Xenopus rods do not degenerate. Contrasting phototransduction in vitamin A-deprived Xenopus rods with phototransduction in constitutively active mammalian rods may provide new understanding of the mechanisms that lead to retinal degeneration. The photocurrents of Xenopus tadpole rods were measured with suction electrode recordings, and guanylate cyclase activity was measured with the IBMX (3-isobutyl-1-methylxanthine) jump technique. The amount of rhodopsin in rods was determined by microspectrophotometry. The vitamin A-deprived rod outer segments were 60% to 70% the length and diameter of the rods in age-matched animals. Approximately 90% of its opsin content was in the free or unbound form. Analogous to bleaching adaptation, the photoresponses were desensitized (10- to 20-fold) and faster. Unlike bleaching adaptation, the vitamin A-deprived rods maintained near normal saturating (dark) current densities by developing abnormally high rates of cGMP synthesis. Their rate of cGMP synthesis in the dark (15 seconds(-1)) was twofold greater than the maximum levels attainable by control rods ( approximately 7 seconds(-1)). Preserving circulating current density and response range appears to be an important goal for rod homeostasis. However, the compensatory changes associated with vitamin A deprivation in Xenopus rods come at the high metabolic cost of a 15-fold increase in basal ATP consumption.

Ejection Fraction: What Does It Measure?

MedlinePlus

... does the term "ejection fraction" mean? What does it measure? Answers from Rekha Mankad, M.D. Ejection fraction ... percentage of blood leaving your heart each time it contracts. During each heartbeat pumping cycle, the heart ...

Spinal injury after ejection in jet pilots: mechanism, diagnosis, followup, and prevention.

PubMed

Rotondo, G

1975-06-01

In order to contribute to the study of spinal injury after ejection., the author analyzed the results of 100 cases of ejections carried out by military and civil Italian jet pilots in a period of 20 years. Of this group, 47 successfully ejected from aircraft without injury; 11 ejections proved fatal. The remaining 42 pilots sutained vertebral fractures, while 27 sustained other traumatic injuries different from spinal fractures. There were 23 vertebral fractures in 15 pilots and the most frequently affected vertebrae were those of the thoraco-lumbar junction. Analysis was make of the pathology, the clinical and radiological profiles, the therapeutic treatment, and the relative aeromedico-legal aspects concerning the temporary unfitness for flying or permanent grounding of the personnel as well as the possible prevention of spinal injury after ejection

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.

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.

Lightning protection using energized Franklin rods

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

Abdel-Salam, M.; Al-Abdul-Latif, U.

1995-12-31

In this paper, the onset criterion of the upward streamers from an energized Franklin rod is formulated as a function of the geometry of the rod and the height and current of the downward leader. The electric field in the vicinity of the lightning rod is calculated using the charge simulation technique. The dependency of the radius of protection on the amplitude of the pulse voltage applied to Franklin rod, the downward leader current and the tip radius and height of the rod is investigated.

Structural Integrity Testing Method for PRSEUS Rod-Wrap Stringer Design

NASA Technical Reports Server (NTRS)

Wang, John T.; Grenoble, Ray W.; Pickell, Robert D.

2012-01-01

NASA Langley Research Center and The Boeing Company are developing an innovative composite structural concept, called PRSEUS, for the flat center section of a future environmentally friendly hybrid wing body (HWB) aircraft. The PRSEUS (Pultruded Rod Stitched Efficient Unitized Structure) concept uses dry textile preforms for the skins, frames, and stiffener webs. The highly loaded stiffeners are made from precured unidirectional carbon/epoxy rods and dry fiber preforms. The rods are wrapped with the dry fiber preforms and a resin infusion process is used to form the rod-wrap stiffeners. The structural integrity of the rod-wrap interface is critical for maintaining the panel s high strength and bending rigidity. No standard testing method exists for testing the strength of the rod-wrap bondline. Recently, Boeing proposed a rod push-out testing method and conducted some preliminary tests using this method. This paper details an analytical study of the rod-wrap bondline. The rod-wrap interface is modeled as a cohesive zone for studying the initiation and growth of interfacial debonding during push-out testing. Based on the correlations of analysis results and Boeing s test data, the adequacy of the rod-wrap testing method is evaluated, and potential approaches for improvement of the test method are proposed.

Optimization of a rod pinch diode radiography source at 2.3 MV

NASA Astrophysics Data System (ADS)

Menge, P. R.; Johnson, D. L.; Maenchen, J. E.; Rovang, D. C.; Oliver, B. V.; Rose, D. V.; Welch, D. R.

2003-08-01

Rod pinch diodes have shown considerable capability as high-brightness flash x-ray sources for penetrating dynamic radiography. The rod pinch diode uses a small diameter (0.4-2 mm) anode rod extended through a cathode aperture. When properly configured, the electron beam born off of the aperture edge can self-insulate and pinch onto the tip of the rod creating an intense, small x-ray source. Sandia's SABRE accelerator (2.3 MV, 40 Ω, 70 ns) has been utilized to optimize the source experimentally by maximizing the figure of merit (dose/spot diameter2) and minimizing the diode impedance droop. Many diode parameters have been examined including rod diameter, rod length, rod material, cathode aperture diameter, cathode thickness, power flow gap, vacuum quality, and severity of rod-cathode misalignment. The configuration producing the greatest figure of merit uses a 0.5 mm diameter gold rod, a 6 mm rod extension beyond the cathode aperture (diameter=8 mm), and a 10 cm power flow gap to produce up to 3.5 rad (filtered dose) at 1 m from a 0.85 mm x-ray on-axis spot (1.02 mm at 3° off axis). The resultant survey of parameter space has elucidated several physics issues that are discussed.

Ultrasonic Structural Health Monitoring to Assess the Integrity of Spinal Growing Rods In Vitro.

PubMed

Oetgen, Matthew E; Goodley, Addison; Yoo, Byungseok; Pines, Darryll J; Hsieh, Adam H

2016-01-01

Rod fracture is a common complication of growing rods and can result in loss of correction, patient discomfort, and unplanned revision surgery. The ability to quantitate rod integrity at each lengthening would be advantageous to avoid this complication. We investigate the feasibility of applying structural health monitoring to evaluate the integrity of growing rods in vitro. Single-rod titanium 4.5-mm growing rod constructs (n = 9), one screw proximally and one distally connected by in-line connectors, were assembled with pedicle screws fixed in polyethylene blocks. Proximal and distal ends were loaded and constructs subjected to cyclic axial compression (0-100 N at 1 Hz), with incrementally increasing maximum compressive loads of 10 N every 9k cycles until failure. Four piezoceramic transducers (PZTs) were mounted along the length the constructs to interrogate the integrity of the rods with an ultrasonic, guided lamb wave approach. Every 9k cycles, an 80 V excitatory voltage was applied to a PZT to generate high-frequency vibrations, which, after propagating through the construct, was detected by the remaining PZTs. Amplitude differences between pre- and postload waveform signals were calculated until rod failure. Average construct lifetime was 88,991 ± 13,398 cycles. All constructs failed due to rod fracture within 21 mm (mean = 15 ± 4.5 mm) of a screw or connector. Amplitude differences between pre- and postload increased in a stepwise fashion as constructs were cycled. Compared to baseline, we found a 1.8 ± 0.6-fold increase in amplitude 18k cycles before failure, a 2.2 ± 1.0-fold increase in amplitude 9k cycles before failure, and a 2.75 ± 1.5-fold increase in amplitude immediately before rod fracture. We describe a potential method for assessing the structural integrity of growing rods using ultrasonic structural health monitoring. These preliminary data demonstrate the ability of periodic rod assessment to detect structural changes in cycled growing rods, which appear to correspond to subclinical rod fatigue before rod fracture. Copyright © 2016 Scoliosis Research Society. Published by Elsevier Inc. All rights reserved.

75 FR 21658 - Carbon and Certain Alloy Steel Wire Rod From Trinidad and Tobago

Federal Register 2010, 2011, 2012, 2013, 2014

2010-04-26

... Certain Alloy Steel Wire Rod From Trinidad and Tobago AGENCY: United States International Trade Commission... Investigation No. 731-TA-961 concerning carbon and certain alloy steel wire rod (``wire rod'') from Trinidad and... of imports of wire rod from Trinidad and Tobago that were sold in the United States at less than fair...

78 FR 2658 - Carbon and Certain Alloy Steel Wire Rod From Mexico: Rescission of Antidumping Duty...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-01-14

... Steel Wire Rod From Mexico: Rescission of Antidumping Duty Administrative Review; 2011-2012 AGENCY... order on carbon and certain alloy steel wire rod (``wire rod'') from Mexico for the period October 1... order on wire rod from Mexico for the period of review, October 1, 2011, through September 30, 2012.\\1...

Models of classical and recurrent novae

NASA Technical Reports Server (NTRS)

Friedjung, Michael; Duerbeck, Hilmar W.

1993-01-01

The behavior of novae may be divided roughly into two separate stages: quiescence and outburst. However, at closer inspection, both stages cannot be separated. It should be attempted to explain features in both stages with a similar model. Various simple models to explain the observed light and spectral observations during post optical maximum activity are conceivable. In instantaneous ejection models, all or nearly all material is ejected in a time that is short compared with the duration of post optical maximum activity. Instantaneous ejection type 1 models are those where the ejected material is in a fairly thin shell, the thickness of which remains small. In the instantaneous ejection type 2 model ('Hubble Flow'), a thick envelope is ejected instantaneously. This envelope remains thick as different parts have different velocities. Continued ejection models emphasize the importance of winds from the nova after optical maximum. Ejection is supposed to occur from one of the components of the central binary, and one can imagine a general swelling of one of the components, so that something resembling a normal, almost stationary, stellar photosphere is observed after optical maximum. The observed characteristics of recurrent novae in general are rather different from those of classical novae, thus, models for these stars need not be the same.

RodZ links MreB to cell wall synthesis to mediate MreB rotation and robust morphogenesis

PubMed Central

Morgenstein, Randy M.; Bratton, Benjamin P.; Nguyen, Jeffrey P.; Ouzounov, Nikolay; Shaevitz, Joshua W.; Gitai, Zemer

2015-01-01

The rod shape of most bacteria requires the actin homolog, MreB. Whereas MreB was initially thought to statically define rod shape, recent studies found that MreB dynamically rotates around the cell circumference dependent on cell wall synthesis. However, the mechanism by which cytoplasmic MreB is linked to extracytoplasmic cell wall synthesis and the function of this linkage for morphogenesis has remained unclear. Here we demonstrate that the transmembrane protein RodZ mediates MreB rotation by directly or indirectly coupling MreB to cell wall synthesis enzymes. Furthermore, we map the RodZ domains that link MreB to cell wall synthesis and identify mreB mutants that suppress the shape defect of ΔrodZ without restoring rotation, uncoupling rotation from rod-like growth. Surprisingly, MreB rotation is dispensable for rod-like shape determination under standard laboratory conditions but is required for the robustness of rod shape and growth under conditions of cell wall stress. PMID:26396257

RodZ links MreB to cell wall synthesis to mediate MreB rotation and robust morphogenesis.

PubMed

Morgenstein, Randy M; Bratton, Benjamin P; Nguyen, Jeffrey P; Ouzounov, Nikolay; Shaevitz, Joshua W; Gitai, Zemer

2015-10-06

The rod shape of most bacteria requires the actin homolog, MreB. Whereas MreB was initially thought to statically define rod shape, recent studies found that MreB dynamically rotates around the cell circumference dependent on cell wall synthesis. However, the mechanism by which cytoplasmic MreB is linked to extracytoplasmic cell wall synthesis and the function of this linkage for morphogenesis has remained unclear. Here we demonstrate that the transmembrane protein RodZ mediates MreB rotation by directly or indirectly coupling MreB to cell wall synthesis enzymes. Furthermore, we map the RodZ domains that link MreB to cell wall synthesis and identify mreB mutants that suppress the shape defect of ΔrodZ without restoring rotation, uncoupling rotation from rod-like growth. Surprisingly, MreB rotation is dispensable for rod-like shape determination under standard laboratory conditions but is required for the robustness of rod shape and growth under conditions of cell wall stress.

Truss beam having convex-curved rods, shear web panels, and self-aligning adapters

NASA Technical Reports Server (NTRS)

Fernandez, Ian M. (Inventor)

2013-01-01

A truss beam comprised of a plurality of joined convex-curved rods with self-aligning adapters (SAA) adhesively attached at each end of the truss beam is disclosed. Shear web panels are attached to adjacent pairs of rods, providing buckling resistance for the truss beam. The rods are disposed adjacent to each other, centered around a common longitudinal axis, and oriented so that adjacent rod ends converge to at least one virtual convergence point on the common longitudinal axis, with the rods' curvature designed to increase prevent buckling for the truss beam. Each SAA has longitudinal bores that provide self-aligning of the rods in the SAA, the self-aligning feature enabling creation of strong adhesive bonds between each SAA and the rods. In certain embodiments of the present invention, pultruded unidirectional carbon fiber rods are coupled with carbon fiber shear web panels and metal SAA(s), resulting in a lightweight, low-cost but strong truss beam that is highly resistant to buckling.

Final report, PT IP-535-C: Test of smaller VSR`s in DR reactor

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

Vaughn, A.D.

1963-04-17

Because of rod-sticking problems at DR Reactor, a knuckle rod of B Reactor design was installed in vertical safety channel number 28. The substitute VSR, which has a smaller diameter than the original DR rod, has been tested for its operational feasibility including both drop time and reactivity effect. The reactivity effect of the rod was estimated by comparison of the reactivity transient caused by insertion of the specific B-type rod after scramming into the pile, with similar transients caused by normal vertical safety rod in an adjacent channel. This document lists the indicated relative control strength of the rodmore » as an empirical basis for future safety calculations. Results indicate that the B-type knuckel rod in DR reactor is about 80% as strong as a normal DR vertical safety rod if used in equivalent flux distribution and location; this makes it reasonable to assume that the local control strength of the B-type knuckel rod is 98 {mu}b.« less

Postural effects on the noninvasive baselines of ventricular performance

NASA Technical Reports Server (NTRS)

Lance, V. Q.; Spodick, D. H.

1977-01-01

The effects of posture on time-based noninvasive measurements were determined utilizing the sequence supine-sitting-standing in a formal protocol in which observer biases were eliminated by blinding the measurement and calculation phases. Compared to the supine posture, the sitting and standing postures produced significant increases in heart rate, isovolumic contraction time, pre-ejection period and pre-ejection period/left-ventricular ejection time and significant decreases in ejection time and ejection time index. The response patterns are consistent with the hemodynamic correlates cited in the literature which show increased adrenergic activity and decreased venous return in the sitting and standing postures, the effect on venous return being dominant.

Recovery from exercise at varying work loads - Time course of responses of heart rate and systolic intervals

NASA Technical Reports Server (NTRS)

Nandi, P. S.; Spodick, D. H.

1977-01-01

The time course of the recovery period was characterized by noninvasive measurements after 4 minute bicycle exercise at 3 separate work loads in volunteers with normal peak responses. Most responses started immediately to return toward resting control values. Left ventricular ejection time and stroke volume change are discussed. Changes in pre-ejection period were determined by changes in isovolume contraction time, and factors affecting the degree and rate of return are considered. The rates of change in the ejection time index and in the ratio pre-ejection period/left ventricular ejection time were virtually independent of load throughout most of recovery.

Space probe/satellite ejection apparatus for spacecraft

NASA Technical Reports Server (NTRS)

Smyly, H. M.; Miller, C. D.; Cloyd, R. A.; Heller, C. (Inventor)

1984-01-01

An ejection apparatus for spinning and propelling objects for ejection from a spacecraft at a desired velocity and rotational speed is discussed. The apparatus includes a launch cradle on which the space object to be ejected rests. The cradle is rotatably supported by a central hub secured to the upper end of the pneumatic cylinder piston shaft. Release mechanisms consisting of a retractable pin and locking lug is utilized to hold the cradle and object to be ejected. The release mechanism has a fixed barrier member which holds the retractable pin in engagement with the locking lug until release by upward movement of the launch cradle beyond the barrier height.

Implications of Vehicle Roll Direction on Occupant Ejection and Injury Risk

PubMed Central

Gloeckner, D. Claire; Moore, Tara L. A.; Steffey, Duane; Bare, Cleve; Corrigan, Catherine Ford

2006-01-01

Vehicle roll direction and occupant position have been shown to affect occupant kinematics. Data from NASS-CDS were analyzed for risk of serious or greater injuries and ejection with respect to the position of the occupant (near side or far side). The risk of AIS 3+ injuries was higher for unrestrained occupants, for ejected occupants, for occupants involved in rollovers with higher numbers of quarter turns, and for far side occupants. Near side occupants had an increased risk of partial ejection in rollovers consisting of one complete roll or less. Occupant roll direction did not affect risk of complete ejection. PMID:16968635

Techniques and equipment for assessing the structural integrity of subterranean tower anchor rods

DOEpatents

Hinz, William R.; Parker, Matthew J.

2001-01-01

Techniques and equipment for evaluating structural integrity of buried anchor rods in situ are disclosed. The techniques avoid excavation of soil and avoid, or at least reduce, the possibility of damage to the rods or the concrete in which they may be embedded when evaluations are conducted. Instead, ultrasonic energy is transmitted through the rod from a portable transducer, and returned energy (in either or both of direct and mode-converted states) may be analyzed to assist in detecting flaws, corrosion, wastage, or other degradation of the rod. Data from a field evaluation may be compared with baseline data maintained either for a specific rod or for rods of similar composition and length (or both), and periodic field evaluations of a rod may be used to analyze trends in its structure over time.

A Full-Core Resonance Self-Shielding Method Using a Continuous-Energy Quasi–One-Dimensional Slowing-Down Solution that Accounts for Temperature-Dependent Fuel Subregions and Resonance Interference

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

Liu, Yuxuan; Martin, William; Williams, Mark

In this paper, a correction-based resonance self-shielding method is developed that allows annular subdivision of the fuel rod. The method performs the conventional iteration of the embedded self-shielding method (ESSM) without subdivision of the fuel to capture the interpin shielding effect. The resultant self-shielded cross sections are modified by correction factors incorporating the intrapin effects of radial variation of the shielded cross section, radial temperature distribution, and resonance interference. A quasi–one-dimensional slowing-down equation is developed to calculate such correction factors. The method is implemented in the DeCART code and compared with the conventional ESSM and subgroup method with benchmark MCNPmore » results. The new method yields substantially improved results for both spatially dependent reaction rates and eigenvalues for typical pressurized water reactor pin cell cases with uniform and nonuniform fuel temperature profiles. Finally, the new method is also proved effective in treating assembly heterogeneity and complex material composition such as mixed oxide fuel, where resonance interference is much more intense.« less

Monte Carlo analyses of TRX slightly enriched uranium-H/sub 2/O critical experiments with ENDF/B-IV and related data sets (AWBA Development Program)

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

Hardy, J. Jr.

1977-12-01

Four H/sub 2/O-moderated, slightly-enriched-uranium critical experiments were analyzed by Monte Carlo methods with ENDF/B-IV data. These were simple metal-rod lattices comprising Cross Section Evaluation Working Group thermal reactor benchmarks TRX-1 through TRX-4. Generally good agreement with experiment was obtained for calculated integral parameters: the epi-thermal/thermal ratio of U238 capture (rho/sup 28/) and of U235 fission (delta/sup 25/), the ratio of U238 capture to U235 fission (CR*), and the ratio of U238 fission to U235 fission (delta/sup 28/). Full-core Monte Carlo calculations for two lattices showed good agreement with cell Monte Carlo-plus-multigroup P/sub l/ leakage corrections. Newly measured parameters for themore » low energy resonances of U238 significantly improved rho/sup 28/. In comparison with other CSEWG analyses, the strong correlation between K/sub eff/ and rho/sup 28/ suggests that U238 resonance capture is the major problem encountered in analyzing these lattices.« less

The Modeling of Advanced BWR Fuel Designs with the NRC Fuel Depletion Codes PARCS/PATHS

DOE PAGES

Ward, Andrew; Downar, Thomas J.; Xu, Y.; ...

2015-04-22

The PATHS (PARCS Advanced Thermal Hydraulic Solver) code was developed at the University of Michigan in support of U.S. Nuclear Regulatory Commission research to solve the steady-state, two-phase, thermal-hydraulic equations for a boiling water reactor (BWR) and to provide thermal-hydraulic feedback for BWR depletion calculations with the neutronics code PARCS (Purdue Advanced Reactor Core Simulator). The simplified solution methodology, including a three-equation drift flux formulation and an optimized iteration scheme, yields very fast run times in comparison to conventional thermal-hydraulic systems codes used in the industry, while still retaining sufficient accuracy for applications such as BWR depletion calculations. Lastly, themore » capability to model advanced BWR fuel designs with part-length fuel rods and heterogeneous axial channel flow geometry has been implemented in PATHS, and the code has been validated against previously benchmarked advanced core simulators as well as BWR plant and experimental data. We describe the modifications to the codes and the results of the validation in this paper.« less

Role of recoverin in rod photoreceptor light adaptation.

PubMed

Morshedian, Ala; Woodruff, Michael L; Fain, Gordon L

2018-04-15

Recoverin is a small molecular-weight, calcium-binding protein in rod outer segments that can modulate the rate of rhodopsin phosphorylation. We describe two additional and perhaps more important functions during photoreceptor light adaptation. Recoverin influences the rate of change of adaptation. In wild-type rods, sensitivity and response integration time adapt with similar time constants of 150-200 ms. In Rv-/- rods lacking recoverin, sensitivity declines faster and integration time is already shorter and not significantly altered. During steady light exposure, rod circulating current slowly increases during a time course of tens of seconds, gradually extending the operating range of the rod. In Rv-/- rods, this mechanism is deleted, steady-state currents are already larger and rods saturate at brighter intensities. We propose that recoverin modulates spontaneous and light-activated phophodiesterase-6, the phototransduction effector enzyme, to increase sensitivity in dim light but improve responsiveness to change in brighter illumination. Recoverin is a small molecular-weight, calcium-binding protein in rod outer segments that binds to G-protein receptor kinase 1 and can alter the rate of rhodopsin phosphorylation. A change in phosphorylation should change the lifetime of light-activated rhodopsin and the gain of phototransduction, but deletion of recoverin has little effect on the sensitivity of rods either in the dark or in dim-to-moderate background light. We describe two additional functions perhaps of greater physiological significance. (i) When the ambient intensity increases, sensitivity and integration time decrease in wild-type (WT) rods with similar time constants of 150-200 ms. Recoverin is part of the mechanism controlling this process because, in Rv-/- rods lacking recoverin, sensitivity declines more rapidly and integration time is already shorter and not further altered. (ii) During steady light exposure, WT rod circulating current slowly increases during a time course of tens of seconds, gradually extending the operating range of the rod. In Rv-/- rods, this mechanism is also deleted, steady-state currents are already larger and rods saturate at brighter intensities. We argue that neither (i) nor (ii) can be caused by modulation of rhodopsin phosphorylation but may instead be produced by direct modulation of phophodiesterase-6 (PDE6), the phototransduction effector enzyme. We propose that recoverin in dark-adapted rods keeps the integration time long and the spontaneous PDE6 rate relatively high to improve sensitivity. In background light, the integration time is decreased to facilitate detection of change and motion and the spontaneous PDE6 rate decreases to augment the rod working range. © 2018 The Authors. The Journal of Physiology © 2018 The Physiological Society.

CONTROL RODS FOR NUCLEAR REACTORS

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

Bell, F.R.

1963-01-16

A means for controlling the control rod in emergency, when it is desired to shutdown the reactor with the shortest possible delay, is described. When the emergency occurs the control rod is allowed to drop freely under gravity from the control rod support tube into the bore in the reactor core. A normal shutdown is reached almost at the lowest rod position. In the shut-down position and also below it, the control rod had its full effect of reducing the level of activity in the core. When the shut-down position was reached, a brake came into action to decelerate themore » rod and reduce shock and the likelihood of damage. (C.E.S.)« less

CRDM with separate SCRAM latch engagement and locking

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

Dodd, Christopher D.; DeSantis, Paul K.; Stambaugh, Kevin J.

A control rod drive mechanism (CRDM) configured to latch onto the lifting rod of a control rod assembly and including separate latch engagement and latch holding mechanisms. A CRDM configured to latch onto the lifting rod of a control rod assembly and including a four-bar linkage closing the latch, wherein the four-bar linkage biases the latch closed under force of gravity.

77 FR 13545 - Carbon and Certain Alloy Steel Wire Rod From Mexico: Notice of Final Results of Antidumping Duty...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-03-07

... Steel Wire Rod From Mexico: Notice of Final Results of Antidumping Duty Administrative Review AGENCY... results of the administrative review of the antidumping duty order on carbon and certain alloy steel wire rod (wire rod) from Mexico.\\1\\ This review covers imports of wire rod from ArcelorMittal Las Truchas...

78 FR 63450 - Carbon and Certain Alloy Steel Wire Rod From Brazil, Indonesia, Mexico, Moldova, Trinidad and...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-10-24

...-805, A-274-804, A-823-812] Carbon and Certain Alloy Steel Wire Rod From Brazil, Indonesia, Mexico... on carbon and certain alloy steel wire rod (``wire rod'') from Brazil, Indonesia, Mexico, Moldova... published the notice of initiation of the sunset reviews of the antidumping duty orders on wire rod from...

Summary report, Flexible VSR`s and VSR channel sleeve development programs

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

Kempf, F.J.

1963-11-15

(VSR = vertical safety rod.) This report summarizes results of development programs which have evaluated vertical rod channel sleeving materials and provided flexible vertical rods, acceptable for both interim use before rod channel sleeving, and for subsequent use in sleeved channels. B{sub 4}C is the rod material; graphite and Al oxide are among the sleeve materials.

[Experimental study of recovery force of surface-modified TiNi memory alloy rod].

PubMed

Wang, Aiyuan; Peng, Jiang; Zhang, Xian; Xu, Wenjin; Wang, Xing; Sun, Minxue; Lu, Shibi

2006-08-01

The recovery force of Ti-Nb coated and uncoated TiNi shape memory alloy rods was investigated. The rods were 6.0 mm, 6.5 mm and 7.0 mm in diameter respectively. The mean transition temperature was 33.0 degrees C. The rods were stored at -18 degrees C and pre-bent with a three-point bending fixture, the span was 20. 0 centimeters and the deflections were 5.0 mm, 10.0 mm, 15.0 mm and 20.0 mm, respectively. The rods were then heated in a constant temperature saline solution chamber. The experimental temperature was 37.0 C and 50.0 C respectively. The recovery force was measured in a constant displacement mode on biomaterial test machine. The results showed that the recovery force of the memory alloy rod increased with increasing recovery temperature, rod diameter and deformation of both Ti-Nb coated and uncoated surface. The recovery force of Ti-Nb coated rods of 6.0 and 6.5 millimeter in diameter was lower than the uncoated rods in the same diameter. However, the recovery force of 7.0-mm-diameter rods showed no significant difference between coated and uncoated surface.

Experimental Study on Surrogate Nuclear Fuel Rods under Reversed Cyclic Bending

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

Wang, Hong; Wang, Jy-An John

The mechanical behavior of spent nuclear fuel (SNF) rods under reversed cyclic bending or bending fatigue must be understood to evaluate their vibration integrity in a transportation environment. This is especially important for high-burnup fuels (>45 GWd/MTU), which have the potential for increased structural damage. It has been demonstrated that the bending fatigue of SNF rods can be effectively studied using surrogate rods. In this investigation, surrogate rods made of stainless steel (SS) 304 cladding and aluminum oxide pellets were tested under load or moment control at a variety of amplitude levels at 5 Hz using the Cyclic Integrated Reversible-Bendingmore » Fatigue Tester developed at Oak Ridge National Laboratory. The behavior of the rods was further characterized using flexural rigidity and hysteresis data, and fractography was performed on the failed rods. The proposed surrogate rods captured many of the characteristics of deformation and failure mode observed in SNF, including the linear-to-nonlinear deformation transition and large residual curvature in static tests, PPI and PCMI failure mechanisms, and large variation in the initial structural condition. Rod degradation was measured and characterized by measuring the flexural rigidity; the degradation of the rigidity depended on both the moment amplitude applied and the initial structural condition of the rods. It was also shown that a cracking initiation site can be located on the internal surface or the external surface of cladding. Finally, fatigue damage to the bending rods can be described in terms of flexural rigidity, and the fatigue life of rods can be predicted once damage model parameters are properly evaluated. The developed experimental approach, test protocol, and analysis method can be used to study the vibration integrity of SNF rods in the future.« less

Ultrasound - Aided ejection in micro injection molding

NASA Astrophysics Data System (ADS)

Masato, D.; Sorgato, M.; Lucchetta, G.

2018-05-01

In this work, an ultrasound-aided ejection system was designed and tested for different polymers (PS, COC and POM) and mold topographies. The proposed solution aims at reducing the ejection friction by decreasing the adhesion component of the frictional force, which is controlled by the contact area developed during the filling stage of the injection molding process. The experimental results indicate a positive effect of ultrasound vibration on the friction force values, with a maximum reduction of 16. Moreover, it is demonstrated that the ultrasound effect is strictly related to both polymer selection and mold roughness. The combined effect on the ejection force of mold surface roughness, melt viscosity during filling and polymer elastic modulus at ejection was modeled to the experimental data, in order to demonstrate that the effect of ultrasound vibration on the ejection friction reduction is due to the heating of the contact interface and the consequent reduction of the polymer elastic modulus.

Effect of substrate thickness on ejection of phenylalanine molecules adsorbed on free-standing graphene bombarded by 10 keV C60

NASA Astrophysics Data System (ADS)

Golunski, M.; Verkhoturov, S. V.; Verkhoturov, D. S.; Schweikert, E. A.; Postawa, Z.

2017-02-01

Molecular dynamics computer simulations have been employed to investigate the effect of substrate thickness on the ejection mechanism of phenylalanine molecules deposited on free-standing graphene. The system is bombarded from the graphene side by 10 keV C60 projectiles at normal incidence and the ejected particles are collected both in transmission and reflection directions. It has been found that the ejection mechanism depends on the substrate thickness. At thin substrates mostly organic fragments are ejected by direct collisions between projectile atoms and adsorbed molecules. At thicker substrates interaction between deforming topmost graphene sheet and adsorbed molecules becomes more important. As this process is gentle and directionally correlated, it leads predominantly to ejection of intact molecules. The implications of the results to a novel analytical approach in Secondary Ion Mass Spectrometry based on ultrathin free-standing graphene substrates and a transmission geometry are discussed.

Two billion years of magmatism recorded from a single Mars meteorite ejection site

PubMed Central

Lapen, Thomas J.; Righter, Minako; Andreasen, Rasmus; Irving, Anthony J.; Satkoski, Aaron M.; Beard, Brian L.; Nishiizumi, Kunihiko; Jull, A. J. Timothy; Caffee, Marc W.

2017-01-01

The timing and nature of igneous activity recorded at a single Mars ejection site can be determined from the isotope analyses of Martian meteorites. Northwest Africa (NWA) 7635 has an Sm-Nd crystallization age of 2.403 ± 0.140 billion years, and isotope data indicate that it is derived from an incompatible trace element–depleted mantle source similar to that which produced a geochemically distinct group of 327- to 574-million-year-old “depleted” shergottites. Cosmogenic nuclide data demonstrate that NWA 7635 was ejected from Mars 1.1 million years ago (Ma), as were at least 10 other depleted shergottites. The shared ejection age is consistent with a common ejection site for these meteorites. The spatial association of 327- to 2403-Ma depleted shergottites indicates >2 billion years of magmatism from a long-lived and geochemically distinct volcanic center near the ejection site. PMID:28164153

ELECTROMAGNETIC APPARATUS FOR MOVING A ROD

DOEpatents

Young, J.N.

1958-04-22

An electromagnetic apparatus for moving a rod-like member in small steps in either direction is described. The invention has particular application in the reactor field where the reactor control rods must be moved only a small distance and where the use of mechanical couplings is impractical due to the high- pressure seals required. A neutron-absorbing rod is mounted in a housing with gripping uaits that engage the rod, and coils for magnetizing the gripping units to make them grip, shift, and release the rod are located outside the housing.

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.

CONTROL SYSTEM FOR NEUTRONIC REACTORS

DOEpatents

Crever, F.E.

1962-05-01

BS>A slow-acting shim rod for control of major variations in reactor neutron flux and a fast-acting control rod to correct minor flux variations are employed to provide a sensitive, accurate control system. The fast-acting rod is responsive to an error signal which is produced by changes in the neutron flux from a predetermined optimum level. When the fast rod is thus actuated in a given direction, means is provided to actuate the slow-moving rod in that direction to return the fast rod to a position near the midpoint of its control range. (AEC)

Calcium-induced calcium release in rod photoreceptor terminals boosts synaptic transmission during maintained depolarization

PubMed Central

Cadetti, Lucia; Bryson, Eric J.; Ciccone, Cory A.; Rabl, Katalin; Thoreson, Wallace B.

2008-01-01

We examined the contribution of calcium-induced calcium release (CICR) to synaptic transmission from rod photoreceptor terminals. Whole-cell recording and confocal calcium imaging experiments were conducted on rods with intact synaptic terminals in a retinal slice preparation from salamander. Low concentrations of ryanodine stimulated calcium increases in rod terminals, consistent with the presence of ryanodine receptors. Application of strong depolarizing steps (−70 to −10 mV) exceeding 200 ms or longer in duration evoked a wave of calcium that spread across the synaptic terminals of voltage-clamped rods. This secondary calcium increase was blocked by high concentrations of ryanodine, indicating it was due to CICR. Ryanodine (50 μM) had no significant effect on rod calcium current (Ica) although it slightly diminished rod light-evoked voltage responses. Bath application of 50 μM ryanodine strongly inhibited light-evoked currents in horizontal cells. Whether applied extracellularly or delivered into the rod cell through the patch pipette, ryanodine (50 μM) also inhibited excitatory post-synaptic currents (EPSCs) evoked in horizontal cells by depolarizing steps applied to rods. Ryanodine caused a preferential reduction in the later portions of EPSCs evoked by depolarizing steps of 200 ms or longer. These results indicate that CICR enhances calcium increases in rod terminals evoked by sustained depolarization, which in turn acts to boost synaptic exocytosis from rods. PMID:16819987

The effect of different screw-rod design on the anti-rotational torque: a biomechanical comparison of three conventional screw-rod constructs.

PubMed

Huang, Zifang; Wang, Chongwen; Fan, Hengwei; Sui, Wenyuan; Li, Xueshi; Wang, Qifei; Yang, Junlin

2017-07-28

Screw-rod constructs have been widely used to correct spinal deformities, but the effects of different screw-rod systems on anti-rotational torque have not been determined. This study aimed to analyze the biomechanical effect of different rod-screw constructs on anti-rotational torque. Three conventional spinal screw-rod systems (Legacy, RF-F-10 and USSII) were used to test the anti-rotational torque in the material test machine. ANOVA was performed to evaluate the anti-rotational capacity of different pedicle screws-rod constructs. The anti-rotational torque of Legacy group, RF-F-10 group and USSII group were 12.3 ± 1.9 Nm, 6.8 ± 0.4 Nm, and 3.9 ± 0.8 Nm, with a P value lower than 0.05. This results indicated that the Legacy screws-rod construct could provide a highest anti-rotation capacity, which is 68% and 210% greater than RF-F-10 screw-rod construct and USSII screw-rod respectively. The anti-rotational torque may be mainly affected by screw cap and groove design. Our result showed the anti-rotational torque are: Legacy system > RF-F-10 system > USSII system, suggesting that appropriate rod-screw constructs selection in surgery may be vital for anti-rotational torque improvement and preventing derotation correction loss.

Simultaneous double-rod rotation technique in posterior instrumentation surgery for correction of adolescent idiopathic scoliosis.

PubMed

Ito, Manabu; Abumi, Kuniyoshi; Kotani, Yoshihisa; Takahata, Masahiko; Sudo, Hideki; Hojo, Yoshihiro; Minami, Akio

2010-03-01

The authors present a new posterior correction technique consisting of simultaneous double-rod rotation using 2 contoured rods and polyaxial pedicle screws with or without Nesplon tapes. The purpose of this study is to introduce the basic principles and surgical procedures of this new posterior surgery for correction of adolescent idiopathic scoliosis. Through gradual rotation of the concave-side rod by 2 rod holders, the convex-side rod simultaneously rotates with the the concave-side rod. This procedure does not involve any force pushing down the spinal column around the apex. Since this procedure consists of upward pushing and lateral translation of the spinal column with simultaneous double-rod rotation maneuvers, it is simple and can obtain thoracic kyphosis as well as favorable scoliosis correction. This technique is applicable not only to a thoracic single curve but also to double major curves in cases of adolescent idiopathic scoliosis.

30. Engine controls and valve gear, looking aft on main ...

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

30. Engine controls and valve gear, looking aft on main (promenade) deck level. Threaded admission valve lift rods (two at immediate left of chronometer) permit adjustment of valve timing in lower and upper admission valves of cylinder (left rod controls lower valve, right rod upper valve). Valve rods are lifted by jaw-like "wipers" during operation. Exhaust valve lift rods and wipers are located to right of chronometer. Crank at extreme right drives valve wiper shaft when engaged to end of eccentric rod, shown under "Crank Indicator" dial. Pair of handles to immediate left of admission valve rods control condenser water valves; handles to right of exhaust valve rods control feedwater flow to boilers from pumps. Gauges indicate boiler pressure (left) and condenser vacuum (right); "Crank Indicator" on wall aids engineer in keeping engine crank off "dead-center" at stop so that engine may be easily restarted. - Steamboat TICONDEROGA, Shelburne Museum Route 7, Shelburne, Chittenden County, VT

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.

Fuel bundle design for enhanced usage of plutonium fuel

DOEpatents

Reese, Anthony P.; Stachowski, Russell E.

1995-01-01

A nuclear fuel bundle includes a square array of fuel rods each having a concentration of enriched uranium and plutonium. Each rod of an interior array of the rods also has a concentration of gadolinium. The interior array of rods is surrounded by an exterior array of rods void of gadolinium. By this design, usage of plutonium in the nuclear reactor is enhanced.

Fuel bundle design for enhanced usage of plutonium fuel

DOEpatents

Reese, A.P.; Stachowski, R.E.

1995-08-08

A nuclear fuel bundle includes a square array of fuel rods each having a concentration of enriched uranium and plutonium. Each rod of an interior array of the rods also has a concentration of gadolinium. The interior array of rods is surrounded by an exterior array of rods void of gadolinium. By this design, usage of plutonium in the nuclear reactor is enhanced. 10 figs.

Linear motion device and method for inserting and withdrawing control rods

DOEpatents

Smith, Jay E.

1984-01-01

A linear motion device, more specifically a control rod drive mechanism (CRDM) for inserting and withdrawing control rods into a reactor core, is capable of independently and sequentially positioning two sets of control rods with a single motor stator and rotor. The CRDM disclosed can control more than one control rod lead screw without incurring a substantial increase in the size of the mechanism.

Relationships between egg-recognition and egg-ejection in a grasp-ejector species.

PubMed

Soler, Manuel; Ruiz-Raya, Francisco; Roncalli, Gianluca; Ibáñez-Álamo, Juan Diego

2017-01-01

Brood parasitism frequently leads to a total loss of host fitness, which selects for the evolution of defensive traits in host species. Experimental studies have demonstrated that recognition and rejection of the parasite egg is the most common and efficient defence used by host species. Egg-recognition experiments have advanced our knowledge of the evolutionary and coevolutionary implications of egg recognition and rejection. However, our understanding of the proximate mechanisms underlying both processes remains poor. Egg rejection is a complex behavioural process consisting of three stages: egg recognition, the decision whether or not to reject the putative parasitic egg and the act of ejection itself. We have used the blackbird (Turdus merula) as a model species to explore the relationship between egg recognition and the act of egg ejection. We have manipulated the two main characteristics of parasitic eggs affecting egg ejection in this grasp-ejector species: the degree of colour mimicry (mimetic and non-mimetic, which mainly affects the egg-recognition stage of the egg-rejection process) and egg size (small, medium and large, which affects the decision to eject), while maintaining a control group of non-parasitized nests. The behaviour of the female when confronted with an experimental egg was filmed using a video camera. Our results show that egg touching is an indication of egg recognition and demonstrate that blackbirds recognized (i.e., touched) non-mimetic experimental eggs significantly more than mimetic eggs. However, twenty per cent of the experimental eggs were touched but not subsequently ejected, which confirms that egg recognition does not necessarily mean egg ejection and that accepting parasitic eggs, at least sometimes, is the consequence of acceptance decisions. Regarding proximate mechanisms, our results show that the delay in egg ejection is not only due to recognition problems as usually suggested, given that experimental eggs are not touched significantly more often. Thus, the delay in egg ejection is mainly the consequence of a delay in the decision to eject, probably triggered by mechanical constraints imposed by eggs that are harder to eject (i.e. larger). Our results offer important information on the relationships between recognition and ejection and contribute to a better understanding of host defences against brood parasites.

Relationships between egg-recognition and egg-ejection in a grasp-ejector species

PubMed Central

Soler, Manuel; Ruiz-Raya, Francisco; Roncalli, Gianluca; Ibáñez-Álamo, Juan Diego

2017-01-01

Brood parasitism frequently leads to a total loss of host fitness, which selects for the evolution of defensive traits in host species. Experimental studies have demonstrated that recognition and rejection of the parasite egg is the most common and efficient defence used by host species. Egg-recognition experiments have advanced our knowledge of the evolutionary and coevolutionary implications of egg recognition and rejection. However, our understanding of the proximate mechanisms underlying both processes remains poor. Egg rejection is a complex behavioural process consisting of three stages: egg recognition, the decision whether or not to reject the putative parasitic egg and the act of ejection itself. We have used the blackbird (Turdus merula) as a model species to explore the relationship between egg recognition and the act of egg ejection. We have manipulated the two main characteristics of parasitic eggs affecting egg ejection in this grasp-ejector species: the degree of colour mimicry (mimetic and non-mimetic, which mainly affects the egg-recognition stage of the egg-rejection process) and egg size (small, medium and large, which affects the decision to eject), while maintaining a control group of non-parasitized nests. The behaviour of the female when confronted with an experimental egg was filmed using a video camera. Our results show that egg touching is an indication of egg recognition and demonstrate that blackbirds recognized (i.e., touched) non-mimetic experimental eggs significantly more than mimetic eggs. However, twenty per cent of the experimental eggs were touched but not subsequently ejected, which confirms that egg recognition does not necessarily mean egg ejection and that accepting parasitic eggs, at least sometimes, is the consequence of acceptance decisions. Regarding proximate mechanisms, our results show that the delay in egg ejection is not only due to recognition problems as usually suggested, given that experimental eggs are not touched significantly more often. Thus, the delay in egg ejection is mainly the consequence of a delay in the decision to eject, probably triggered by mechanical constraints imposed by eggs that are harder to eject (i.e. larger). Our results offer important information on the relationships between recognition and ejection and contribute to a better understanding of host defences against brood parasites. PMID:28170402

Rate of change of left ventricular ejection fraction during exercise is superior to the peak ejection fraction for predicting functionally significant coronary artery disease.

PubMed Central

Sridhara, B S; Bhattacharya, S; Liu, X J; Broadhurst, P; Lahiri, A

1993-01-01

OBJECTIVE--To detect and characterise rapid temporal changes in the left ventricular response to exercise in patients with ischaemic heart disease and to relate these changes to the functional severity of coronary artery disease. BACKGROUND--The gamma camera does not allow the detection of rapid changes in cardiac function during exercise radionuclide ventriculography, the monitoring of which may improve the assessment of patients with ischaemic heart disease. METHODS--A miniature nuclear probe (Cardioscint) was used to monitor continuously left ventricular function during exercise in 31 patients who had coronary angiography for suspected coronary artery disease. A coronary angiographic jeopardy score was calculated for each patient. RESULTS--The coronary jeopardy score ranged from 0 to 12 (median 4). Ejection fraction fell significantly during exercise from 46% to 34%. Patients were divided into two groups based on the response of their ejection fraction to exercise. In 14 patients (group I), the peak change in ejection fraction coincided with the end of exercise, whereas in the other 17 patients (group II) the peak change in ejection fraction occurred before the end of exercise, resulting in a brief plateau. The peak change in ejection fraction and the time to its occurrence were independent predictors of coronary jeopardy (r = -0.59, p < 0.001 for peak change and r = -0.69, p < 0.001 for time to that change). The rate of change in ejection fraction was the strongest predictor of coronary jeopardy (r = -0.81, p < 0.001). In group I the peak change in ejection fraction was a poor predictor severity of coronary disease (r = -0.28, NS), whereas the time to peak and the rate of change in ejection fraction were good predictors (r = -0.65 and r = -0.73, p < 0.01). In group II the peak, the time to the peak, and the rate of change in ejection fraction were good predictors of coronary jeopardy (r = -0.75, r = -0.61, and r = -0.83, p < 0.01). CONCLUSION--The rate of change of ejection fraction during exercise can be assessed by continuous monitoring of left ventricular function with the nuclear probe, and is the best predictor of functionally significant coronary artery disease. PMID:8280514

Fretting corrosion behavior of nitinol spinal rods in conjunction with titanium pedicle screws.

PubMed

Lukina, Elena; Kollerov, Mikhail; Meswania, Jay; Khon, Alla; Panin, Pavel; Blunn, Gordon W

2017-03-01

Untypical corrosion damage including erosions combined with the build-up of titanium oxide as a corrosion product on the surface of explanted Nitinol spinal rods in the areas where it was in contact with titanium pedicle screw head is reported. It was suggested that Nitinol rods might have inferior fretting corrosion resistance compared with that made of titanium or CoCr. Fretting corrosion of Nitinol spinal rods with titanium (Ti6Al4V) pedicle screws were tested in-vitro by conducting a series of potentiostatic measurements of the peak-to-peak values of fretting corrosion current under bending in a 10% solution of calf serum in PBS. The test included Nitinol rods locked in titanium pedicle screws of different designs. Performance of commercially available titanium (Ti6Al4V) and CoCr spinal rods was also investigated for a comparison. Corrosion damage observed after the in-vitro tests was studied using SEM and EDAX analysis and was compared with patterns on Nitinol rods retrieved 12months after initial surgery. Metal ions level was measured in the test media after in-vitro experiments and in the blood and tissues of the patients who had the rods explanted. The results of this study revealed that Nitinol spinal rods locked in Ti pedicle screws are susceptible to fretting corrosion demonstrating higher fretting corrosion current compared with commercially used Ti6Al4V and CoCr rods. On the surface of Nitinol rods after in-vitro tests and on those retrieved from the patients similar corrosion patterns were observed. Improved resistance to fretting corrosion was observed with Nitinol rods in the in-vitro tests where pedicle screws were used with a stiffer locking mechanism. Since the development of the localized corrosion damage might increase the risk of premature fatigue failure of the rods and result in leaching of Ni ions, it is concluded that Nitinol rods should not be used in conjunction with Ti pedicle screws without special protection especially where the design provides a high degree of mobility to the rods. Copyright © 2016 Elsevier B.V. All rights reserved.

Nuclear core and fuel assemblies

DOEpatents

Downs, Robert E.

1981-01-01

A fast flux nuclear core of a plurality of rodded, open-lattice assemblies having a rod pattern rotated relative to a rod support structure pattern. Elongated fuel rods are oriented on a triangular array and laterally supported by grid structures positioned along the length of the assembly. Initial inter-assembly contact is through strongbacks at the corners of the support pattern and peripheral fuel rods between adjacent assemblies are nested so as to maintain a triangular pitch across a clearance gap between the other portions of adjacent assemblies. The rod pattern is rotated relative to the strongback support pattern by an angle .alpha. equal to sin .sup.-1 (p/2c), where p is the intra-assembly rod pitch and c is the center-to-center spacing among adjacent assemblies.

Reactor control rod timing system. [LMFBR

DOEpatents

Wu, P.T.K.

1980-03-18

A fluid driven jet-edge whistle timing system is described 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.

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.

Convergent synthesis of multiporphyrin light-harvesting rods

DOEpatents

Lindsey, Jonathan S.; Loewe, Robert S.

2003-08-05

The present invention provides a convergent method for the synthesis of light harvesting rods. The rods are oligomers of the formula A.sup.1 (A.sup.b+1).sub.b, wherein b is at least 1, A.sup.1 through A.sup.b+1 are covalently coupled rod segments, and each rod segment A.sup.1 through A.sup.1+b comprises a compound of the formula X.sup.1 (X.sup.m+1).sub.m wherein m is at least 1 and X.sup.1 through X.sup.m+1 are covalently coupled porphyrinic macrocycles. Light harvesting arrays and solar cells containing such light harvesting rods are also described, along with intermediates useful in such methods and rods produced by such methods.

Birefringence-balanced polarimetric optical fiber sensor for high-temperature measurements

NASA Technical Reports Server (NTRS)

Wang, Anbo; Wang, George Z.; Murphy, Kent A.; Claus, Richard O.

1992-01-01

A birefringence-balanced polarimetric multimode fiber temperature sensor is proposed and demonstrated. Two single-crystal sapphire rods are incorporated into the sensor head. They are connected end to end in such a way that the slow axis of the first rod is aligned with the fast axis of the second rod, referred to as the referencing rod. Since the lengths of the two rods are chosen to be almost the same, the original birefringence of the first rod is balanced by that of the second rod. A light-emitting diode serves as the light source. This sensor has been experimentally demonstrated for high-temperature measurements as high as 1500 C. A sensitivity of 5 C has been obtained.

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)

An Evaluation of a New Format for Presenting Ejection Information in a NATOPS Manual.

DTIC Science & Technology

1979-11-01

Assessment-the subject’s awareness of ejection system limits and knowledge of the specific principles and relationships involved in the ejection decision...percti & le pilot ejecting cannern tintiong onfigursesan at~ 71 knete arrtaeei.l From" th front cockpit. c. Normal aircraft pitc For conditions shown it...40) Arlington, VA 22209 700 Robbins Avenue * 1 CDR P.R. Chatelier Philadelphia, PA 19111 Office of the Undersecretary of Defense for Research

Multi-function magnetic jack control drive mechanism

DOEpatents

Bollinger, L.R.; Crawford, D.C.

1983-10-06

A multi-function magnetic jack control drive mechanism for controlling a nuclear reactor is provided. The mechanism includes an elongate pressure housing in which a plurality of closely spaced drive rods are located. Each drive rod is connected to a rod which is insertable in the reactor core. An electromechanical stationary latch device is provided which is actuatable to hold each drive rod stationary with respect to the pressure housing. An electromechanical movable latch device is also provided for each one of the drive rods. Each movable latch device is provided with a base and is actuatable to hold a respective drive rod stationary with respect to the base. An electromechanical lift device is further provided for each base which is actuatable for moving a respective base longitudinally along the pressure housing. In this manner, one or more drive rods can be moved in the pressure housing by sequentially and repetitively operating the electromechanical devices. Preferably, each latch device includes a pair of opposed latches which grip teeth located on the respective drive rod. Two, three, or four drive rods can be located symmetrically about the longitudinal axis of the pressure housing.

Multi-function magnetic jack control drive mechanism

DOEpatents

Bollinger, Lawrence R.; Crawford, Donald C.

1986-01-01

A multi-function magnetic jack control drive mechanism for controlling a nuclear reactor is provided. The mechanism includes an elongate pressure housing in which a plurality of closely spaced drive rods are located. Each drive rod is connected to a rod which is insertable in the reactor core. An electromechanical stationary latch device is provided which is actuatable to hold each drive rod stationary with respect to the pressure housing. An electromechanical movable latch device is also provided for each one of the drive rods. Each movable latch device is provided with a base and is actuatable to hold a respective drive rod stationary with respect to the base. An electromechanical lift device is further provided for each base which is actuatable for moving a respective base longitudinally along the pressure housing. In this manner, one or more drive rods can be moved in the pressure housing by sequentially and repetitively operating the electromechanical devices. Preferably, each latch device includes a pair of opposed latches which grip teeth located on the respective drive rod. Two, three, or four drive rods can be located symmetrically about the longitudinal axis of the pressure housing.

Slip-spring model of entangled rod-coil block copolymers

NASA Astrophysics Data System (ADS)

Wang, Muzhou; Likhtman, Alexei E.; Olsen, Bradley D.

2015-03-01

Understanding the dynamics of rod-coil block copolymers is important for optimal design of functional nanostructured materials for organic electronics and biomaterials. Recently, we proposed a reptation theory of entangled rod-coil block copolymers, predicting the relaxation mechanisms of activated reptation and arm retraction that slow rod-coil dynamics relative to coil and rod homopolymers, respectively. In this work, we introduce a coarse-grained slip-spring model of rod-coil block copolymers to further explore these mechanisms. First, parameters of the coarse-grained model are tuned to match previous molecular dynamics simulation results for coils, rods, and block copolymers. For activated reptation, rod-coil copolymers are shown to disfavor configurations where the rod occupies curved portions of the entanglement tube of randomly varying curvature created by the coil ends. The effect of these barriers on diffusion is quantitatively captured by considering one-dimensional motion along an entanglement tube with a rough free energy potential. Finally, we analyze the crossover between the two mechanisms. The resulting dynamics from both mechanisms acting in combination is faster than from each one individually.

Superfund record of decision amendment (EPA Region 5): Allied Chemical and Ironton Coke, Ironton, OH, September 30, 1998

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

Not Available

This decision document, together with the Allied Chemical/Ironton Coke Record of Decision (ROD) dated December 28, 1990, the first Allied Chemical/Ironton Coke ROD Amendment dated July 31, 1995 (ROD Amendment No 1), and the second ROD Amendment dated September 4, 1997 (ROD Amendment No 2), presents the selected remedial action for the Allied Chemical/Ironton Coke site. The remedy selected in the 1990 ROD, 1995 ROD Amendment No. 1, and 1997 ROD Amendment No. 2 for the site is a final remedial action. Through ROD Amendment No. 3 the following components of the selected remedy are being modified: Replace in-situ bioremediationmore » of 457,000 cubic yards of soil in Lagoons 1--4 with hot spot excavation and wetland development; and Replace incineration of Lagoon 5 materials with recycling, treatment, and/or disposal of the K087 listed waste in an approved off-site hazardous waste facility and the use of the remaining material, excluding debris, as an alternative fuel.« less

Large Deformation of an Elastic Rod with Structural Anisotropy Subjected to Fluid Flow

NASA Astrophysics Data System (ADS)

Hassani, Masoud; Mureithi, Njuki; Gosselin, Frederick

2015-11-01

In the present work, we seek to understand the fundamental mechanisms of three-dimensional reconfiguration of plants by studying the large deformation of a flexible rod in fluid flow. Flexible rods made of Polyurethane foam and reinforced with Nylon fibers are tested in a wind tunnel. The rods have bending-torsion coupling which induces a torsional deformation during asymmetric bending. A mathematical model is also developed by coupling the Kirchhoff rod theory with a semi-empirical drag formulation. Different alignments of the material frame with respect to the flow direction and a range of structural properties are considered to study their effect on the deformation of the flexible rod and its drag scaling. Results show that twisting causes the flexible rods to reorient and bend with the minimum bending rigidity. It is also found that the drag scaling of the rod in the large deformation regime is not affected by torsion. Finally, using a proper set of dimensionless numbers, the state of a bending and twisting rod is characterized as a beam undergoing a pure bending deformation.

Experimental measurement of coil-rod-coil block copolymer tracer diffusion through entangled coil homopolymers

PubMed Central

Wang, Muzhou; Timachova, Ksenia; Olsen, Bradley D.

2014-01-01

The diffusion of coil-rod-coil triblock copolymers in entangled coil homopolymers is experimentally measured and demonstrated to be significantly slower than rod or coil homopolymers of the same molecular weight. A model coil-rod-coil triblock was prepared by expressing rodlike alanine-rich α-helical polypeptides in E. coli and conjugating coillike poly(ethylene oxide) (PEO) to both ends to form coil-rod-coil triblock copolymers. Tracer diffusion through entangled PEO homopolymer melts was measured using forced Rayleigh scattering at various rod lengths, coil molecular weights, and coil homopolymer concentrations. For rod lengths, L, that are close to the entanglementh length, a, the ratio between triblock diffusivity and coil homopolymer diffusivity decreases monotonically and is only a function of L/a, in quantitative agreement with previous simulation results. For large rod lengths, diffusion follows an arm retraction scaling, which is also consistent with previous theoretical predictions. These experimental results support the key predictions of theory and simulation, suggesting that the mismatch in curvature between rod and coil entanglement tubes leads to the observed diffusional slowing. PMID:25484454

Preparation of novel layer-stack hexagonal CdO micro-rods by a pre-oxidation and subsequent evaporation process

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

Peng, Kun, E-mail: kpeng@hnu.edu.cn; Hunan Province Key Laboratory for Spray Deposition Technology and Application, Hunan University, Changsha 410082; Jiang, Pan

2014-12-15

Graphical abstract: Layer-stack hexagonal cadmium oxide (CdO) micro-rods were prepared. - Highlights: • Novel hexagonal layer-stack structure CdO micro-rods were synthesized by a thermal evaporation method. • The pre-oxidation, vapor pressure and substrate nature play a key role on the formation of CdO rods. • The formation mechanism of CdO micro-rods was explained. - Abstract: Novel layer-stack hexagonal cadmium oxide (CdO) micro-rods were prepared by pre-oxidizing Cd granules and subsequent thermal oxidation under normal atmospheric pressure. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were performed to characterize the phase structure and microstructure. The pre-oxidation process, vapor pressure and substratemore » nature were the key factors for the formation of CdO micro-rods. The diameter of micro-rod and surface rough increased with increasing of thermal evaporation temperature, the length of micro-rod increased with the increasing of evaporation time. The formation of hexagonal layer-stack structure was explained by a vapor–solid mechanism.« less

[Novel Device for Creating Multiple Artificial Chordae Loops in Mitral Valve Repair].

PubMed

Shimamura, Yoshiei; Maisawa, Kazuma

2017-08-01

A novel device to create multiple artificial chordae loops for mitral repair is developed. The device consists of a circular metal base with a removable central rod on one end, which can easily be attached or removed by screwing into a hole located on the base, and 51 fixed rods placed radially around the central rod at distances of 10~60 mm from the central rod. A needle with CV-4 e-polytetrafluoroethylene suture is passed through a pledget, and the suture is looped from the central rod around the fixed rod located at the desired loop length. The needle is then passed back through the pledget. The suture is tied over the pledget, bringing it in contact with the central rod. When multiple loops of various lengths are required, different fixed rods located at distances corresponding to the required loop lengths are used. Following creation of the necessary loops, the central rod is unscrewed, and the loops are released from the device. Construction of artificial chordae with this device is quick, reliable, reproducible, and increases the technical possibilities for mitral valve repair.

Fabrication of Nanosized Island-Like CdO Crystallites-Decorated TiO₂ Rod Nanocomposites via a Combinational Methodology and Their Low-Concentration NO₂ Gas-Sensing Behavior.

PubMed

Liang, Yuan-Chang; Xu, Nian-Cih; Wang, Chein-Chung; Wei, Da-Hua

2017-07-10

TiO₂-CdO composite rods were synthesized through a hydrothermal method and sputtering thin-film deposition. The hydrothermally derived TiO₂ rods exhibited a rectangular cross-sectional crystal feature with a smooth surface, and the as-synthesized CdO thin film exhibited a rounded granular surface feature. Structural analyses revealed that the CdO thin film sputtered onto the surfaces of the TiO₂ rods formed a discontinuous shell layer comprising many island-like CdO crystallites. The TiO₂-CdO composite rods were highly crystalline, and their surfaces were rugged. A comparison of the NO₂ gas-sensing properties of the CdO thin film, TiO₂ rods, and TiO₂-CdO composite rods revealed that the composite rods exhibited superior gas-sensing responses to NO₂ gas than did the CdO thin film and TiO 2 rods, which can be attributed to the microstructural differences and the formation of heterojunctions between the TiO₂ core and CdO crystallites.

Suppressing turbulence of self-propelling rods by strongly coupled passive particles.

PubMed

Su, Yen-Shuo; Wang, Hao-Chen; I, Lin

2015-03-01

The strong turbulence suppression, mainly for large-scale modes, of two-dimensional self-propelling rods, by increasing the long-range coupling strength Γ of low-concentration passive particles, is numerically demonstrated. It is found that large-scale collective rod motion in forms of swirls or jets is mainly contributed from well-aligned dense patches, which can push small poorly aligned rod patches and uncoupled passive particles. The more efficient momentum transfer and dissipation through increasing passive particle coupling leads to the formation of a more ordered and slowed down network of passive particles, which competes with coherent dense active rod clusters. The frustration of active rod alignment ordering and coherent motion by the passive particle network, which interrupt the inverse cascading of forming large-scale swirls, is the key for suppressing collective rod motion with scales beyond the interpassive distance, even in the liquid phase of passive particles. The loosely packed active rods are weakly affected by increasing passive particle coupling due to the weak rod-particle interaction. They mainly contribute to the small-scale modes and high-speed motion.

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.

Solid-state-laser-rod holder

DOEpatents

Gettemy, D.J.; Barnes, N.P.; Griggs, J.E.

1981-08-11

The disclosure relates to a solid state laser rod holder comprising Invar, copper tubing, and epoxy joints. Materials and coefficients of expansion of the components of the holder combine with the rod to produce a joint which will give before the rod itself will. The rod may be lased at about 70 to 80/sup 0/K and returned from such a temperature to room temperature repeatedly without its or the holder's destruction.

Fastening of a High-Strength Composite rod with a Splitted and Wedged end in a Potted Anchor 1. Experimental Investigation

NASA Astrophysics Data System (ADS)

Arnautov, A. K.; Terrasi, G. P.; Kulakov, V. L.; Portnov, G. G.

2014-01-01

The effectiveness of fastening of high-strength unidirectional CFRP/epoxy rods in potted anchors was investigated experimentally. The rods had splitted ends, in which duralumin wedges were glued. The experiments, performed for three types of contact between the composite rods and the potted material, showed that the most effective were full adhesion and adhesion-friction contacts, when the maximum load-carrying capacity of CFRP rods under tension could be reached. The full friction contact was ineffective because of the shear failure of CFRP rods inside the anchorage zone.

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)

Neural net controlled tag gas sampling system for nuclear reactors

DOEpatents

Gross, Kenneth C.; Laug, Matthew T.; Lambert, John D. B.; Herzog, James P.

1997-01-01

A method and system for providing a tag gas identifier to a nuclear fuel rod and analyze escaped tag gas to identify a particular failed nuclear fuel rod. The method and system include disposing a unique tag gas composition into a plenum of a nuclear fuel rod, monitoring gamma ray activity, analyzing gamma ray signals to assess whether a nuclear fuel rod has failed and is emitting tag gas, activating a tag gas sampling and analysis system upon sensing tag gas emission from a failed nuclear rod and evaluating the escaped tag gas to identify the particular failed nuclear fuel rod.

The retinal rod Na(+)/Ca(2+),K(+) exchanger contains a noncleaved signal sequence required for translocation of the N terminus.

PubMed

McKiernan, C J; Friedlander, M

1999-12-31

The retinal rod Na(+)/Ca(2+),K(+) exchanger (RodX) is a polytopic membrane protein found in photoreceptor outer segments where it is the principal extruder of Ca(2+) ions during light adaptation. We have examined the role of the N-terminal 65 amino acids in targeting, translocation, and integration of the RodX using an in vitro translation/translocation system. cDNAs encoding human RodX and bovine RodX through the first transmembrane domain were correctly targeted and integrated into microsomal membranes; deletion of the N-terminal 65 amino acids (aa) resulted in a translation product that was not targeted or integrated. Deletion of the first 65 aa had no effect on membrane targeting of full-length RodX, but the N-terminal hydrophilic domain no longer translocated. Chimeric constructs encoding the first 65 aa of bovine RodX fused to globin were translocated across microsomal membranes, demonstrating that the sequence could function heterologously. Studies of fresh bovine retinal extracts demonstrated that the first 65 aa are present in the native protein. These data demonstrate that the first 65 aa of RodX constitute an uncleaved signal sequence required for the efficient membrane targeting and proper membrane integration of RodX.

The biomechanical consequences of rod reduction on pedicle screws: should it be avoided?

PubMed

Paik, Haines; Kang, Daniel G; Lehman, Ronald A; Gaume, Rachel E; Ambati, Divya V; Dmitriev, Anton E

2013-11-01

Rod contouring is frequently required to allow for appropriate alignment of pedicle screw-rod constructs. When residual mismatch is still present, a rod persuasion device is often used to achieve further rod reduction. Despite its popularity and widespread use, the biomechanical consequences of this technique have not been evaluated. To evaluate the biomechanical fixation strength of pedicle screws after attempted reduction of a rod-pedicle screw mismatch using a rod persuasion device. Fifteen 3-level, human cadaveric thoracic specimens were prepared and scanned for bone mineral density. Osteoporotic (n=6) and normal (n=9) specimens were instrumented with 5.0-mm-diameter pedicle screws; for each pair of comparison level tested, the bilateral screws were equal in length, and the screw length was determined by the thoracic level and size of the vertebra (35 to 45 mm). Titanium 5.5-mm rods were contoured and secured to the pedicle screws at the proximal and distal levels. For the middle segment, the rod on the right side was intentionally contoured to create a 5-mm residual gap between the inner bushing of the pedicle screw and the rod. A rod persuasion device was then used to engage the setscrew. The left side served as a control with perfect screw/rod alignment. After 30 minutes, constructs were disassembled and vertebrae individually potted. The implants were pulled in-line with the screw axis with peak pullout strength (POS) measured in Newton (N). For the proximal and distal segments, pedicle screws on the right side were taken out and reinserted through the same trajectory to simulate screw depth adjustment as an alternative to rod reduction. Pedicle screws reduced to the rod generated a 48% lower mean POS (495±379 N) relative to the controls (954±237 N) (p<.05) and significantly decreased work energy to failure (p<.05). Nearly half (n=7) of the pedicle screws had failed during the reduction attempt with visible pullout of the screw. After reduction, decreased POS was observed in both normal (p<.05) and osteoporotic (p<.05) bone. Back out and reinsertion of the screw resulted in no significant difference in mean POS, stiffness, and work energy to failure (p>.05). In circumstances where a rod is not fully seated within the pedicle screw, the use of a rod persuasion device decreases the overall POS and work energy to failure of the screw or results in outright failure. Further rod contouring or correction of pedicle screw depth of insertion may be warranted to allow for appropriate alignment of the longitudinal rods. Published by Elsevier Inc.

Magnetohydrodynamic simulations of the ejection of a magnetic flux rope

NASA Astrophysics Data System (ADS)

Pagano, P.; Mackay, D. H.; Poedts, S.

2013-06-01

Context. Coronal mass ejections (CME's) are one of the most violent phenomena found on the Sun. One model to explain their occurrence is the flux rope ejection model. In this model, magnetic flux ropes form slowly over time periods of days to weeks. They then lose equilibrium and are ejected from the solar corona over a few hours. The contrasting time scales of formation and ejection pose a serious problem for numerical simulations. Aims: We simulate the whole life span of a flux rope from slow formation to rapid ejection and investigate whether magnetic flux ropes formed from a continuous magnetic field distribution, during a quasi-static evolution, can erupt to produce a CME. Methods: To model the full life span of magnetic flux ropes we couple two models. The global non-linear force-free field (GNLFFF) evolution model is used to follow the quasi-static formation of a flux rope. The MHD code ARMVAC is used to simulate the production of a CME through the loss of equilibrium and ejection of this flux rope. Results: We show that the two distinct models may be successfully coupled and that the flux rope is ejected out of our simulation box, where the outer boundary is placed at 2.5 R⊙. The plasma expelled during the flux rope ejection travels outward at a speed of 100 km s-1, which is consistent with the observed speed of CMEs in the low corona. Conclusions: Our work shows that flux ropes formed in the GNLFFF can lead to the ejection of a mass loaded magnetic flux rope in full MHD simulations. Coupling the two distinct models opens up a new avenue of research to investigate phenomena where different phases of their evolution occur on drastically different time scales. Movies are available in electronic form at http://www.aanda.org

THE PROPERTIES OF DYNAMICALLY EJECTED RUNAWAY AND HYPER-RUNAWAY STARS

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

Perets, Hagai B.; Subr, Ladislav

2012-06-01

Runaway stars are stars observed to have large peculiar velocities. Two mechanisms are thought to contribute to the ejection of runaway stars, both of which involve binarity (or higher multiplicity). In the binary supernova scenario, a runaway star receives its velocity when its binary massive companion explodes as a supernova (SN). In the alternative dynamical ejection scenario, runaway stars are formed through gravitational interactions between stars and binaries in dense, compact clusters or cluster cores. Here we study the ejection scenario. We make use of extensive N-body simulations of massive clusters, as well as analytic arguments, in order to characterizemore » the expected ejection velocity distribution of runaway stars. We find that the ejection velocity distribution of the fastest runaways (v {approx}> 80 km s{sup -1}) depends on the binary distribution in the cluster, consistent with our analytic toy model, whereas the distribution of lower velocity runaways appears independent of the binaries' properties. For a realistic log constant distribution of binary separations, we find the velocity distribution to follow a simple power law: {Gamma}(v){proportional_to}v{sup -8/3} for the high-velocity runaways and v{sup -3/2} for the low-velocity ones. We calculate the total expected ejection rates of runaway stars from our simulated massive clusters and explore their mass function and their binarity. The mass function of runaway stars is biased toward high masses and strongly depends on their velocity. The binarity of runaways is a decreasing function of their ejection velocity, with no binaries expected to be ejected with v > 150 km s{sup -1}. We also find that hyper-runaways with velocities of hundreds of km s{sup -1} can be dynamically ejected from stellar clusters, but only at very low rates, which cannot account for a significant fraction of the observed population of hyper-velocity stars in the Galactic halo.« less

Vertebral fracture after aircraft ejection during Operation Desert Storm.

PubMed

Osborne, R G; Cook, A A

1997-04-01

During Operation Desert Storm, 21 United States and 2 Italian military personnel were held in Iraq as prisoners of war. Of these, 18 had ejected from fixed-wing, ejection seat-equipped, combat aircraft prior to their capture. Of the 18, 6 (33%) had sustained vertebral fractures; 4 of these were compression fractures. This fracture rate is comparable to that of previously studied groups. Fractures were noted to be at several different vertebral sites and after ejecting from a variety of aircraft. Apart from contusions and abrasions, vertebral fractures were the most common injuries discovered in this repatriated population. None of the vertebral fractures produced recognizable neurological disability. The development of vertebral fractures was neither associated with the use of any particular ejection system or aircraft nor did the development of vertebral fractures appear dependent on the age, height or length of service of the affected personnel. Ejected aircrew with low altitude mission profiles seemed more predisposed to vertebral fracture than those at high altitudes, but with a small sample population, this relationship was not statistically significant (p > 0.25). Reliable data were unavailable on aircrew positioning and preparation time for ejection.

Low speed vehicle passenger ejection restraint effectiveness.

PubMed

Seluga, Kristopher J; Ojalvo, Irving U; Obert, Richard M

2005-07-01

Current golf carts and LSV's (Low Speed Vehicles) produce a significant number of passenger ejections during sharp turns. These LSV's do not typically possess seatbelts, but do provide outboard bench seat hip restraints that also serve as handholds. However, many current restraint designs appear incapable of preventing passenger ejections due to their low height and inefficient handhold position. Alternative handhold and hip restraint designs may improve passenger safety. Accordingly, this paper examines minimum size requirements for hip restraints to prevent passenger ejection during sharp turns and evaluates the effectiveness of a handhold mounted at the center of the bench seat. In this study, a simulation of a turning cart supplies the dynamic input to a biomechanical model of an adult male seated in a golf cart. Various restraint combinations are considered, both with and without the central handhold, to determine the likelihood of passenger ejection. It is shown that only the largest restraint geometries prevent passenger ejection. Adequate hip restraints should be much larger than current designs and a central handhold should be provided. In this way, golf cart and LSV manufacturers could reduce passenger ejections and improve fleet safety by incorporating recommendations provided herein.

Luminescent Properties of Eu(III) Chelates on Metal Nanorods

PubMed Central

Zhang, Jian; Fu, Yi; Ray, Krishanu; Wang, Yuan; Lakowicz, Joseph. R.

2013-01-01

In this article, we report the change of optical properties for europium chelates on silver nanorods by near-field interactions. The silver rods were fabricated in a seed-growth method followed by depositing thin layers of silica on the surfaces. The europium chelates were physically absorbed in the silica layers on the silver rods. The silver rods were observed to exhibit two plasmon absorption bands from longitudinal and transverse directions, respectively, centered at 394 and 675 nm, close to absorption and emission bands from the Eu(III) chelates. As a result, the immobilized Eu(III) chelates on the silver rods should have strong interactions with the silver nanorods and lead to greatly improved optical properties. The Eu–Ag rod complexes were observed to have enhanced emission intensity up to 240-fold in comparison with the Eu(III) chelates in the metal-free silica templates. This enhancement is much larger than the value for the Eu(III) chelates on the gold rods or silver spheres indicating the presence of stronger interactions for the Eu(III) chelates with the silver rods. The interactions of Eu(III) chelates with the silver rods were also proven by extremely reduced lifetime. Moreover, the Eu–Ag rod complexes exhibited a polarized emission, which was also due to strong interactions of the Eu(III) chelates with the silver rods. All of these features may promise that the Eu(III)–Ag rod complexes have great potential for use as fluorescence imaging agents in biological assays. PMID:24363816

Method for producing solid or hollow spherical particles of chosen chemical composition and of uniform size

DOEpatents

Hendricks, Charles D.

1988-01-01

A method is provided for producing commercially large quantities of high melting temperature solid or hollow spherical particles of a predetermined chemical composition and having a uniform and controlled size distribution. An end (18, 50, 90) of a solid or hollow rod (20, 48, 88) of the material is rendered molten by a laser beam (14, 44, 82). Because of this, there is no possibility of the molten rod material becoming contaminated with extraneous material. In various aspects of the invention, an electric field is applied to the molten rod end (18, 90), and/or the molten rod end (50, 90) is vibrated. In a further aspect of the invention, a high-frequency component is added to the electric field applied to the molten end of the rod (90). By controlling the internal pressure of the rod, the rate at which the rod is introduced into the laser beam, the environment of the process, the vibration amplitude and frequency of the molten rod end, the electric field intensity applied to the molten rod end, and the frequency and intensity of the component added to the electric field, the uniformity and size distribution of the solid or hollow spherical particles (122) produced by the inventive method is controlled. The polarity of the electric field applied to the molten rod end can be chosen to eliminate backstreaming electrons, which tend to produce run-away heating in the rod, from the process.

Eulerian Formulation of Spatially Constrained Elastic Rods

NASA Astrophysics Data System (ADS)

Huynen, Alexandre

Slender elastic rods are ubiquitous in nature and technology. For a vast majority of applications, the rod deflection is restricted by an external constraint and a significant part of the elastic body is in contact with a stiff constraining surface. The research work presented in this doctoral dissertation formulates a computational model for the solution of elastic rods constrained inside or around frictionless tube-like surfaces. The segmentation strategy adopted to cope with this complex class of problems consists in sequencing the global problem into, comparatively simpler, elementary problems either in continuous contact with the constraint or contact-free between their extremities. Within the conventional Lagrangian formulation of elastic rods, this approach is however associated with two major drawbacks. First, the boundary conditions specifying the locations of the rod centerline at both extremities of each elementary problem lead to the establishment of isoperimetric constraints, i.e., integral constraints on the unknown length of the rod. Second, the assessment of the unilateral contact condition requires, in principle, the comparison of two curves parametrized by distinct curvilinear coordinates, viz. the rod centerline and the constraint axis. Both conspire to burden the computations associated with the method. To streamline the solution along the elementary problems and rationalize the assessment of the unilateral contact condition, the rod governing equations are reformulated within the Eulerian framework of the constraint. The methodical exploration of both types of elementary problems leads to specific formulations of the rod governing equations that stress the profound connection between the mechanics of the rod and the geometry of the constraint surface. The proposed Eulerian reformulation, which restates the rod local equilibrium in terms of the curvilinear coordinate associated with the constraint axis, describes the rod deformed configuration 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.

35. INTERIOR VIEW, SAME AS ABOVE WITH THE FEEDER ROD ...

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

35. INTERIOR VIEW, SAME AS ABOVE WITH THE FEEDER ROD INSERTED INTO THE MACHINE; NOTE THE WOOD FEEDER ROD AND FEEDER ROD REST ON THE BACK OF THE STOOL - LaBelle Iron Works, Thirtieth & Wood Streets, Wheeling, Ohio County, WV

Grid-to-rod flow-induced impact study for PWR fuel in reactor

DOE PAGES

Jiang, Hao; Qu, Jun; Lu, Roger Y.; ...

2016-06-10

The source for grid-to-rod fretting in a pressurized water nuclear reactor (PWR) is the dynamic contact impact from hydraulic flow-induced fuel assembly vibration. In order to support grid-to-rod fretting wear mitigation research, finite element analysis (FEA) was used to evaluate the hydraulic flow-induced impact intensity between the fuel rods and the spacer grids. Three-dimensional FEA models, with detailed geometries of the dimple and spring of the actual spacer grids along with fuel rods, were developed for flow impact simulation. The grid-to-rod dynamic impact simulation provided insights of the contact phenomena at grid-rod interface. Finally, it is an essential and effectivemore » way to evaluate contact forces and provide guidance for simulative bench fretting-impact tests.« less

Influence of ethylene oxide exposure on the extraction of indomethacin from dimethicone polymeric rods.

PubMed

Hurst, P R; Peplow, P V; von Dadelszen, P

1982-05-01

Dimethicone polymeric rods were made to contain 0.3, 2.0, or 3.3% by weight of indomethacin. For each different loading of indomethacin, some of the rods were treated with ethylene oxide at 55 degrees for 1 hr, while others were not exposed to the gas. Treated and untreated rods were sliced, placed in ethanol to extract the indomethacin, and the concentrations of indomethacin in the extracts determined by fluorometry and high-performance liquid chromatography (HPLC). After ethylene oxide treatment, the quantity of indomethacin in the extracts was significantly reduced in rods containing 0.3 and 2.0% indomethacin. For the rods containing 3.3% indomethacin, the recovery of the drug from treated rods was not significantly different from those not exposed.

Correlated cone noise decreases rod signal contributions to the post-receptoral pathways.

PubMed

Hathibelagal, Amithavikram R; Feigl, Beatrix; Zele, Andrew J

2018-04-01

This study investigated how invisible extrinsic temporal white noise that correlates with the activity of one of the three [magnocellular (MC), parvocellular (PC), or koniocellular (KC)] post-receptoral pathways alters mesopic rod signaling. A four-primary photostimulator provided independent control of the rod and three cone photoreceptor excitations. The rod contributions to the three post-receptoral pathways were estimated by perceptually matching a 20% contrast rod pulse by independently varying the LMS (MC pathway), +L-M (PC pathway), and S-cone (KC pathway) excitations. We show that extrinsic cone noise caused a predominant decrease in the overall magnitude and ratio of the rod contributions to each pathway. Thus, the relative cone activity in the post-receptoral pathways determines the relative mesopic rod inputs to each pathway.

Phosphorylation-independent Suppression of Light-activated Visual Pigment by Arrestin in Carp Rods and Cones*

PubMed Central

Tomizuka, Junko; Tachibanaki, Shuji; Kawamura, Satoru

2015-01-01

Visual pigment in photoreceptors is activated by light. Activated visual pigment (R*) is believed to be inactivated by phosphorylation of R* with subsequent binding of arrestin. There are two types of photoreceptors, rods and cones, in the vertebrate retina, and they express different subtypes of arrestin, rod and cone type. To understand the difference in the function between rod- and cone-type arrestin, we first identified the subtype of arrestins expressed in rods and cones in carp retina. We found that two rod-type arrestins, rArr1 and rArr2, are co-expressed in a rod and that a cone-type arrestin, cArr1, is expressed in blue- and UV-sensitive cones; the other cone-type arrestin, cArr2, is expressed in red- and green-sensitive cones. We quantified each arrestin subtype and estimated its concentration in the outer segment of a rod or a cone in the dark; they were ∼0.25 mm (rArr1 plus rArr2) in a rod and 0.6–0.8 mm (cArr1 or cArr2) in a cone. The effect of each arrestin was examined. In contrast to previous studies, both rod and cone arrestins suppressed the activation of transducin in the absence of visual pigment phosphorylation, and all of the arrestins examined (rArr1, rArr2, and cArr2) bound transiently to most probably nonphosphorylated R*. One rod arrestin, rArr2, bound firmly to phosphorylated pigment, and the other two, rArr1 and cArr2, once bound to phosphorylated R* but dissociated from it during incubation. Our results suggested a novel mechanism of arrestin effect on the suppression of the R* activity in both rods and cones. PMID:25713141

Ejection associated injuries within the German Air Force from 1981-1997.

PubMed

Werner, U

1999-12-01

From 1981-1997 there were 86 ejections from 56 aircraft within the German Air Force. Of these, 24 accidents were associated with the F-104 Starfighter, 14 with the PA 200 Tornado, 12 from the F-4 Phantom, 5 from the Alpha Jet and 1 from a MiG 29 Fulcrum. One case involved a front seat pilot, who had already sustained fatal injuries from midair collision, being command ejected by the rear seat pilot. The remaining 85 ejections are the basis of this study. One weapons system officer died from hypothermia after landing in the sea and another from bleeding into the medulla oblongata after flailing; all other participants survived. This is an overall success rate of 97.6%. Of all 85 participants, 12 (14%) were uninjured, 41 (48.2%) were slightly injured, and 30 (35.3%) were severely injured. Typical injuries were those of the spine and lower limbs. The most common severe injury was a vertebral fracture caused by ejection acceleration. This is followed by lower limb injuries received during the parachute landing fall. At the time of ejection, all uninjured crews were flying below 3500 ft altitude and below 260 kn airspeed. Of all ejections from each aircraft type, the percentage of vertebral fractures is highest with the F-4 Phantom (31.8%), followed by the F-104 (16.6%) and the PA 200 Tornado with only 14.8%. The PA 200 is equipped with the most modern type of ejection seat of these aircraft. A conclusion of the gained data is that more modern ejection seat types provide lower injury severity but not fewer total injury numbers, and that the medical data taken during accident investigation should be taken more accurately and in a more standarized fashion to be comparable.

Value of the QRS complex in assessing left ventricular ejection fraction.

PubMed

Askenazi, J; Parisi, A F; Cohn, P F; Freedman, W B; Braunwald, E

1978-03-01

The relation between electrocardiographic findings and the angiographic left ventricular ejection fraction and the augmented ejection fraction after a premature ventricular contraction was investigated in 73 patients with documented chronic coronary artery disease. The patients were separated into four groups according to the presence or absence of abnormal Q waves. Twenty-four patients had diaphragmatic myocardial infarction, 21 had anterior myocardial infarction, 15 had both and 13 had no myocardial infarction. There was no statistically significant differences in cardiac index, left ventricular end-diastolic pressure or number of coronary vessels showing critical narrowing in the four groups. The sum of R waves (in mv) in leads aVL, aVF and V1 to V6 (sigmaR) was correlated with the ejection fraction (EF) and the augmented ejection fraction (EFa). EF in percent = 6.6 sigmaR mv + 9.4 (no. =73, r = 0.61); and EFa in percent = 8.6 sigmaR mv + 11.0 (no. = 73, r = 0.77). Among patients with sigmaR of less than 4.0 mv, augmented ejection fraction was less than 0.45 in 73 percent; among patients with sigmaR of 4.0 mv or more the augmented ejection fraction was greater than 0.45 in 93 percent (P less than 0.001). Thus, the sigmaR, calculated from six precordial and two augmented leads in patients with chronic coronary artery disease, correlated with both ejection fraction and augmented ejection fraction. The electrocardiogram in patients with coronary artery disease may prove useful as a simple, readily available and noninvasive guide in the assessment of left ventricular function in patients with coronary artery disease.

Method of increasing magnetostrictive response of rare earth-iron alloy rods

DOEpatents

Verhoeven, John D.; McMasters, O. Dale; Gibson, Edwin D.; Ostenson, Jerome E.; Finnemore, Douglas K.

1989-04-04

This invention comprises a method of increasing the magnetostrictive response of rare earth-iron (RFe) magnetostrictive alloy rods by a thermal-magnetic treatment. The rod is heated to a temperature above its Curie temperature, viz. from 400.degree. to 600.degree. C.; and, while the rod is at that temperature, a magnetic field is directionally applied and maintained while the rod is cooled, at least below its Curie temperature.

Method of increasing magnetostrictive response of rare earth-iron alloy rods

DOEpatents

Verhoeven, J.D.; McMasters, O.D.; Gibson, E.D.; Ostenson, J.E.; Finnemore, D.K.

1989-04-04

This invention comprises a method of increasing the magnetostrictive response of rare earth-iron (RFe) magnetostrictive alloy rods by a thermal-magnetic treatment. The rod is heated to a temperature above its Curie temperature, viz. from 400 to 600 C; and, while the rod is at that temperature, a magnetic field is directionally applied and maintained while the rod is cooled, at least below its Curie temperature. 2 figs.

Linear motion device and method for inserting and withdrawing control rods

DOEpatents

Smith, J.E.

Disclosed is a linear motion device and more specifically a control rod drive mechanism (CRDM) for inserting and withdrawing control rods into a reactor core. The CRDM and method disclosed is capable of independently and sequentially positioning two sets of control rods with a single motor stator and rotor. The CRDM disclosed can control more than one control rod lead screw without incurring a substantial increase in the size of the mechanism.

Control rod system useable for fuel handling in a gas-cooled nuclear reactor

DOEpatents

Spurrier, Francis R.

1976-11-30

A control rod and its associated drive are used to elevate a complete stack of fuel blocks to a position above the core of a gas-cooled nuclear reactor. A fuel-handling machine grasps the control rod and the drive is unlatched from the rod. The stack and rod are transferred out of the reactor, or to a new location in the reactor, by the fuel-handling machine.

Effect of coolant flow ejection on aerodynamic performance of low-aspect-ratio vanes. 1: Performance with coolant ejection holes plugged

NASA Technical Reports Server (NTRS)

Haas, J. E.; Kofskey, M. G.

1976-01-01

The aerodynamic performance of a low aspect ratio turbine vane designed with coolant flow ejection holes on the vane surfaces was experimentally determined in a full-annular cascade with the coolant ejection holes plugged. The purpose was to establish a baseline for comparison with tests where flow is ejected from the vane surfaces. The vanes were tested over a mean-section ideal critical velocity ratio range of 0.64 to 0.98. This ideal critical velocity ratio corresponds to the vane inlet total to vane aftermixed static pressure ratio at the mean section. The variations in vane efficiency and aftermixed flow conditions with circumferential and radial position were obtained.

Experimental comparison of forces resisting viral DNA packaging and driving DNA ejection

PubMed Central

Keller, Nicholas; Berndsen, Zachary T.; Jardine, Paul J.; Smith, Douglas E.

2018-01-01

We compare forces resisting DNA packaging in bacteriophage phi29 inferred from optical tweezers studies with forces driving DNA ejection inferred from osmotic pressure studies. Ejection forces from 0–80% filling are consistent with a model that assumes a repulsive DNA-DNA interaction potential derived from DNA condensation studies and predicts an inverse spool DNA conformation. Forces resisting packaging from ~80–100% filling are also consistent with this model. However, that electron microscopy does not reveal a spool conformation suggests that this model overestimates bending rigidity and underestimates repulsion. Below 80% filling, inferred ejection forces are higher than those resisting packaging. Although unexpected, this suggests that most force that builds during packaging is available to drive DNA ejection. PMID:28618627

Dark-Adapted Chromatic Perimetry for Measuring Rod Visual Fields in Patients with Retinitis Pigmentosa

PubMed Central

Bennett, Lea D.; Klein, Martin; Locke, Kirsten G.; Kiser, Kelly; Birch, David G.

2017-01-01

Purpose Although rod photoreceptors are initially affected in retinitis pigmentosa (RP), the full-field of rod vision is not routinely characterized due to the unavailability of commercial devices detecting rod sensitivity. The purpose of this study was to quantify rod-mediated vision in the peripheral field from patients with RP using a new commercially available perimeter. Methods Participants had one eye dilated and dark-adapted for 45 minutes. A dark-adapted chromatic (DAC) perimeter tested 80 loci 144° horizontally and 72° vertically with cyan stimuli. The number of rod-mediated loci (RML) were analyzed based on normal cone sensitivity (method 1) and associated with full-field electroretinography (ERG) responses by Pearson's r correlation and linear regression. In a second cohort of patients with RP, RML were identified by two-color perimetry (cyan and red; method 2). The two methods for ascribing rod function were compared by Bland-Altman analysis. Results Method 1 RML were correlated with responses to the 0.01 cd.s/m2 flash (P < 0.001), while total sensitivity to the cyan stimulus showed correlation with responses to the 3.0 cd.s/m2 flash (P < 0.0001). Method 2 detected a mean of 10 additional RML compared to method 1. Conclusions Scotopic fields measured with the DAC detected rod sensitivity across the full visual field, even in some patients who had nondetectable rod ERGs. Two-color perimetry is warranted when sensitivity to the cyan stimulus is reduced to ≤20 dB to get a true estimation of rod function. Translational Relevance Many genetic forms of retinitis pigmentosa (RP) are caused by mutations in rod-specific genes. However, treatment trials for patients with RP have relied primarily on photopic (cone-mediated) tests as outcome measures because there are a limited number of available testing methods designed to evaluate rod function. Thus, efficient methods for quantifying rod-mediated vision are needed for the rapidly increasing numbers of clinical trials. PMID:28798898

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.

Test Fixture for Determination of Energy Absorbing Capabilities of Composite Materials

NASA Technical Reports Server (NTRS)

Lavoie, J. Andre (Inventor); Jackson, Karen E. (Inventor); Morton, John (Inventor)

1998-01-01

The present invention provides a fixture for supporting an elongated specimen for crush testing. The fixture comprises a base plate. four guiding rods, a sliding plate, four support rods and two collars. The guiding rods connect to the base plate and extend in a direction substantially perpendicular to the base plate. The sliding plate has linear bearings which encircle the guiding rods and enable translation of the sliding plate along the axis of each guiding rod. The four supporting rods mount to the base plate and also extend in a direction substantially perpendicular to the base plate. Each support rod has a keyway for a wedge which contacts the elongated specimen and holds the specimen in place during crushing. Each collar lies above the sliding plate and holds a pair of support rods on their ends opposite the ends connected to the base plate. A spherical bearing sits on top of the sliding plate and transfers an applied load to the sliding plate, which moves downward and crushes the elongated specimen.

Test fixture for determination of energy absorbing capabilities of composite materials

NASA Technical Reports Server (NTRS)

Lavoie, J. Andre (Inventor); Jackson, Karen E. (Inventor); Morton, John (Inventor)

1994-01-01

The present invention provides a fixture for supporting an elongated specimen for crush testing. The fixture comprises a base plate, four guiding rods, a sliding plate, four support rods and two collars. The guiding rods connect to the base plate and extend in a direction substantially perpendicular to the base plate. The sliding plate has linear bearings which encircle the guiding rods and enable translation of the sliding plate along the axis of each guiding rod. The four supporting rods mount to the base plate and also extend in a direction substantially perpendicular to the base plate. Each support rod has a keyway for a wedge which contacts the elongated specimen and holds the specimen in place during crushing. Each collar lies above the sliding plate and holds a pair of support rods on their ends opposite the ends connected to the base plate. A spherical bearing sits on top of the sliding plate and transfers an applied load to the sliding plate, which moves downward and crushes the elongated specimen.

High sensitivity rod photoreceptor input to the blue-yellow color opponent pathway in macaque retina

PubMed Central

Field, Greg D.; Greschner, Martin; Gauthier, Jeffrey L.; Rangel, Carolina; Shlens, Jonathon; Sher, Alexander; Marshak, David W.; Litke, Alan M.; Chichilnisky, E.J.

2009-01-01

Small bistratified cells (SBCs) in the primate retina carry a major blue-yellow opponent signal to the brain. Here we show that SBCs also carry signals from rod photoreceptors, with the same sign as S cone input. SBCs exhibited robust responses under low scotopic conditions (<0.01 P*/rod/s). Physiological and anatomical experiments indicated that this rod input arose from the AII amacrine cell mediated rod pathway. Rod and cone signals were both present in SBCs at mesopic light levels. We discuss three implications of these findings. First, more retinal circuits than previously thought may multiplex rod and cone signals, efficiently exploiting the limited number of optic nerve fibers. Second, signals from AII amacrine cells may diverge to most or all of the <20 RGC types in the peripheral primate retina. Third, rod input to SBCs may be the substrate for behavioral biases toward perception of blue at mesopic light levels. PMID:19668201

Recruitment of Rod Photoreceptors from Short-Wavelength-Sensitive Cones during the Evolution of Nocturnal Vision in Mammals.

PubMed

Kim, Jung-Woong; Yang, Hyun-Jin; Oel, Adam Phillip; Brooks, Matthew John; Jia, Li; Plachetzki, David Charles; Li, Wei; Allison, William Ted; Swaroop, Anand

2016-06-20

Vertebrate ancestors had only cone-like photoreceptors. The duplex retina evolved in jawless vertebrates with the advent of highly photosensitive rod-like photoreceptors. Despite cones being the arbiters of high-resolution color vision, rods emerged as the dominant photoreceptor in mammals during a nocturnal phase early in their evolution. We investigated the evolutionary and developmental origins of rods in two divergent vertebrate retinas. In mice, we discovered genetic and epigenetic vestiges of short-wavelength cones in developing rods, and cell-lineage tracing validated the genesis of rods from S cones. Curiously, rods did not derive from S cones in zebrafish. Our study illuminates several questions regarding the evolution of duplex retina and supports the hypothesis that, in mammals, the S-cone lineage was recruited via the Maf-family transcription factor NRL to augment rod photoreceptors. We propose that this developmental mechanism allowed the adaptive exploitation of scotopic niches during the nocturnal bottleneck early in mammalian evolution. Published by Elsevier Inc.

Modern Protection Against Lightning Strikes

NASA Astrophysics Data System (ADS)

Moore, C.

2005-05-01

The application of science to provide protection against lightning strikes began around 1750 when Benjamin Franklin who invented the lightning rod in an effort to discharge thunderclouds. Instead of preventing lightning as he expected, his rods have been quite successful as strike receptors, intercepting cloud-to ground discharges and conducting them to Earth without damage to the structures on which they are mounted. In the years since Franklin's invention there has been little attention paid to the rod configuration that best serves as a strike receptor but Franklin's original ideas continue to be rediscovered and promoted. Recent measurements of the responses of variously configured rods to nearby strikes indicate that sharp-tipped rods are not the optimum configuration to serve as strike receptors since the ionization of the air around their tips limits the strength of the local electric fields created by an approaching lightning leader. In these experiments, fourteen blunt-tipped rods exposed in strike-reception competitions with nearby sharp-tipped rods were struck by lightning but none of the sharp-tipped rods were struck.

Extracting and analyzing ejection fraction values from electronic echocardiography reports in a large health maintenance organization.

PubMed

Xie, Fagen; Zheng, Chengyi; Yuh-Jer Shen, Albert; Chen, Wansu

2017-12-01

The left ventricular ejection fraction value is an important prognostic indicator of cardiovascular outcomes including morbidity and mortality and is often used clinically to indicate severity of heart disease. However, it is usually reported in free-text echocardiography reports. We developed and validated a computerized algorithm to extract ejection fraction values from echocardiography reports and applied the algorithm to a large volume of unstructured echocardiography reports between 1995 and 2011 in a large health maintenance organization. A total of 621,856 echocardiography reports with a description of ejection fraction values or systolic functions were identified, of which 70 percent contained numeric ejection fraction values and the rest (30%) were text descriptions explicitly indicating the systolic left ventricular function. The 12.1 percent (16.0% for male and 8.4% for female) of these extracted ejection fraction values are <45 percent. Validation conducted based on a random sample of 200 reports yielded 95.0 percent sensitivity and 96.9 percent positive predictive value.

SU-E-T-328: Dosimetric Impact of Cobalt-Chrome Stabilization Hardware in Paraspinal Radiation Therapy

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

Tang, G; LoSasso, T; Saleh, Z

2015-06-15

Purpose: Due to saturation, high density materials Result in an apparent density of 3.2 g/cm{sup 3} in CT images. The true density of traditional titanium stabilization rods (∼4.4 g/cm{sup 3}) is typically ignored in treatment planning. This may not be acceptable for new cobalt-chrome rods with a density of 8.5 g/cm{sup 3}. This study reports the dosimetric impact of cobalt-chrome rods in paraspinal radiotherapy. Methods: For titanium and cobalt-chrome rods, two planning studies were done for both IMRT and VMAT in Varian Eclipse using AAA. 1) The effect of planning without assigning the true rod density was assessed by comparingmore » plans generated with the apparent density and recalculated with the true density for titanium and cobalt-chrome. 2) To test if TPS can compensate for high density rods during optimization. Furthermore, TPS calculation accuracy was verified using MapCheck for a single 20 x 10 cm{sup 2} field. The MapCheck was incrementally shifted to achieve measurement resolution of 1 mm. Results: PTV coverage was ∼0.3% and ∼4.7% lower in plans that were recalculated with the true rod density of titanium and cobalt-chrome, respectively. PTV coverage can be maintained if the correct density is used in optimization. Measurements showed that TPS overestimated the dose locally by up to 11% for cobalt-chrome rods and up to 4% for titanium rods if the density is incorrect. With density corrected, maximum local differences of 6% and 3% were seen for cobalt-chrome and titanium rods, respectively. At 2 cm beneath a rod, electrons scattered from the side of the rod increased the lateral dose and diminished as depth increases. TPS was not able to account for this effect properly even with the true rod density assigned. Conclusion: Neglecting the true density of cobalt-chrome rods can cause under coverage to the PTV. Assigning the correct density during treatment planning can minimize unexpected decrease in PTV dose.« less

High quality factor whispering gallery modes from self-assembled hexagonal GaN rods grown by metal-organic vapor phase epitaxy.

PubMed

Tessarek, C; Sarau, G; Kiometzis, M; Christiansen, S

2013-02-11

Self-assembled GaN rods were grown on sapphire by metal-organic vapor phase epitaxy using a simple two-step method that relies first on a nitridation step followed by GaN epitaxy. The mask-free rods formed without any additional catalyst. Most of the vertically aligned rods exhibit a regular hexagonal shape with sharp edges and smooth sidewall facets. Cathodo- and microphotoluminescence investigations were carried out on single GaN rods. Whispering gallery modes with quality factors greater than 4000 were measured demonstrating the high morphological and optical quality of the self-assembled GaN rods.

Device and method for redirecting electromagnetic signals

DOEpatents

Garcia, Ernest J.

1999-01-01

A device fabricated to redirect electromagnetic signals, the device including a primary driver adapted to provide a predetermined force, a linkage system coupled to the primary driver, a pusher rod rotationally coupled to the linkage system, a flexible rod element attached to the pusher rod and adapted to buckle upon the application of the predetermined force, and a mirror structure attached to the flexible rod element at one end and to the substrate at another end. When the predetermined force buckles the flexible rod element, the mirror structure and the flexible rod element both move to thereby allow a remotely-located electromagnetic signal directed towards the device to be redirected.

Fast-acting nuclear reactor control device

DOEpatents

Kotlyar, Oleg M.; West, Phillip B.

1993-01-01

A fast-acting nuclear reactor control device for moving and positioning a fety control rod to desired positions within the core of the reactor between a run position in which the safety control rod is outside the reactor core, and a shutdown position in which the rod is fully inserted in the reactor core. The device employs a hydraulic pump/motor, an electric gear motor, and solenoid valve to drive the safety control rod into the reactor core through the entire stroke of the safety control rod. An overrunning clutch allows the safety control rod to freely travel toward a safe position in the event of a partial drive system failure.

Neural net controlled tag gas sampling system for nuclear reactors

DOEpatents

Gross, K.C.; Laug, M.T.; Lambert, J.B.; Herzog, J.P.

1997-02-11

A method and system are disclosed for providing a tag gas identifier to a nuclear fuel rod and analyze escaped tag gas to identify a particular failed nuclear fuel rod. The method and system include disposing a unique tag gas composition into a plenum of a nuclear fuel rod, monitoring gamma ray activity, analyzing gamma ray signals to assess whether a nuclear fuel rod has failed and is emitting tag gas, activating a tag gas sampling and analysis system upon sensing tag gas emission from a failed nuclear rod and evaluating the escaped tag gas to identify the particular failed nuclear fuel rod. 12 figs.

Development of Rod Function in Term Born and Former Preterm Subjects

PubMed Central

Fulton, Anne B.; Hansen, Ronald M.; Moskowitz, Anne

2009-01-01

Purpose Provide an overview of some of our electroretinographic and psychophysical studies of normal development of rod function and their application to retinopathy of prematurity (ROP). Methods Electroretinographic (ERG) responses to full-field stimuli were recorded from dark adapted subjects. Rod photoreceptor sensitivity, SROD, was calculated by fit of a biochemical model of the activation of phototransduction to the ERG a-wave. Dark adapted psychophysical thresholds for detecting 2° spots in parafoveal (10° eccentric) and peripheral (30° eccentric) retina were measured and the difference between the thresholds, Δ10-30, was examined as a function of age. SROD and Δ10-30 in term born and former preterm subjects were compared. Results In term born infants, (1) the normal developmental increase in SROD changes proportionately with the amount of rod visual pigment, rhodopsin, and (2) rod mediated function in central retina is immature compared to that in peripheral retina. In subjects born prematurely, deficits in rod photoreceptor sensitivity persist long after active ROP has resolved. Maturation of rod mediated thresholds in the central retina is prolonged by mild ROP. Conclusions Characterization of the development of normal rod and rod mediated function provides a foundation for understanding ROP. PMID:19483509

Equation of State Effects on Binary Neutron Star and Neutron Star-Black Hole Merger Ejecta

NASA Astrophysics Data System (ADS)

Rizzo, Monica; Pankow, Chris; Kalogera, Vassiliki; Coughlin, Scott; Chase, Eve; Imperato, Sam

2018-01-01

Binary neutron stars (BNSs) and neutron star-black hole (NSBH) binaries are not only potential sources of gravitational waves (GWs), but also are thought to generate phenomena such as kilonova, which have proven to be difficult to catch with electromagnetic (EM) instruments. Kilonovae are believed to arise from the radioactive decay of nuclear matter ejected from NSBH and BNS mergers. As they spiral toward each other, neutron stars (NSs), composed of highly dense nuclear matter, are torn apart by their companion's gravity and eject matter. The amount of matter they eject depends sensitively on the composition of NSs, which is described by a nuclear equation of state (EOS). Using fit formulas for ejected mass from Kawaguchi et. al. (2016) and T. Dietrich and M. Ujevic (2016), for NSBH and BNS respectively, we calculate the amount of mass ejected given the initial parameters (masses, black hole spin, etc.) of NSBH and BNS systems. We then predict the distribution of ejected matter for populations of NSBH and BNS mergers, assuming a different EOS for each population. Using formulas derived from The Kilonova Handbook (Metzger, 2016), we can use the calculated ejected mass to generate light curves which, along with GW detections, can be used to place constraints on an EOS for NSs when GW detections are made. We find that the amount of ejected matter observed is distinct for most EOSs, though to draw any solid conclusions about NS composition, joint GW wave and EM counterpart detections are necessary.

Left atrial ejection force predicts the outcome after catheter ablation for paroxysmal atrial fibrillation.

PubMed

Kishima, Hideyuki; Mine, Takanao; Takahashi, Satoshi; Ashida, Kenki; Ishihara, Masaharu; Masuyama, Tohru

2018-02-01

Left atrium (LA) systolic dysfunction is observed in the early stages of atrial fibrillation (AF) prior to LA anatomical change. We investigated whether LA systolic dysfunction predicts recurrent AF after catheter ablation (CA) in patients with paroxysmal AF. We studied 106 patients who underwent CA for paroxysmal AF. LA systolic function was assessed with the LA emptying volume = Maximum LA volume (LAV max ) - Minimum LA volume (LAV min ), LA emptying fraction = [(LAV max - LAV min )/LAV max ] × 100, and LA ejection force calculated with Manning's method [LA ejection force = (0.5 × ρ × mitral valve area × A 2 )], where ρ is the blood density and A is the late-diastolic mitral inflow velocity. Recurrent AF was detected in 35/106 (33%) during 14.6 ± 9.1 months. Univariate analysis revealed reduced LA ejection force, decreased LA emptying fraction, larger LA diameter, and elevated brain natriuretic peptide as significant variables. On multivariate analysis, reduced LA ejection force and larger LA diameter were independently associated with recurrent AF. Moreover, patients with reduced LA ejection force and larger LA diameter had a higher risk of recurrent AF than preserved LA ejection force (log-rank P = 0.0004). Reduced LA ejection force and larger LA diameter were associated with poor outcome after CA for paroxysmal AF, and could be a new index to predict recurrent AF. © 2017 Wiley Periodicals, Inc.

Flexible growing rods: a pilot study to determine if polymer rod constructs may provide stability to skeletally immature spines

PubMed Central

2015-01-01

Background Surgical treatments for early onset scoliosis (EOS), including growing rod constructs, involve many complications. Some are due to biomechanical factors. A construct that is more flexible than current instrumentation systems may reduce complications. The purpose of this preliminary study was to determine spine range of motion (ROM) after implantation of simulated growing rod constructs with a range of clinically relevant structural properties. The hypothesis was that ROM of spines instrumented with polyetheretherketone (PEEK) rods would be greater than metal rods and lower than noninstrumented controls. Further, adjacent segment motion was expected to be lower with polymer rods compared to conventional systems. Methods Biomechanical tests were conducted on 6 skeletally immature porcine thoracic spines (domestic swine, 35-40 kg). Spines were harvested after death from swine that had been utilized for other studies (IACUC approved) which had not involved the spine. Paired pedicle screws were used as anchors at proximal and distal levels. Specimens were tested under the following conditions: control, then dual rods of PEEK (6.25 mm), titanium (4 mm), and CoCr (5 mm) alloy. Lateral bending (LB) and flexion-extension (FE) moments of ±5 Nm were applied. Vertebral rotations were measured using video. Differences were determined by two-tailed t-tests and Bonferroni correction with four primary comparisons: PEEK vs control and PEEK vs CoCr, in LB and FE (α=0.05/4). Results In LB, ROM of specimens with PEEK rods was lower than control at each instrumented level. ROM was greater for PEEK rods than both Ti and CoCr at every instrumented level. Mean ROM at proximal and distal noninstrumented levels was lower for PEEK than for Ti and CoCr. In FE, mean ROM at proximal and distal noninstrumented levels was lower for PEEK than for metal. Combining treated levels, in LB, ROM for PEEK rods was 35% of control (p<0.0001) and 270% of CoCr rods (p<0.01). In FE, ROM with PEEK was 27% of control (p<0.001) and 180% of CoCr (p<0.01). Conclusions PEEK rods decreased flexibility versus noninstumented controls, and increased flexibility versus metal rods. Smaller increases in ROM at proximal and distal adjacent motion segments occurred with PEEK compared to metal rods, which may help decrease junctional kyphosis. Flexible growing rods may eventually help improve treatment options for young patients with severe deformity. PMID:25810752

Automatic segmentation of the left ventricle in a cardiac MR short axis image using blind morphological operation

NASA Astrophysics Data System (ADS)

Irshad, Mehreen; Muhammad, Nazeer; Sharif, Muhammad; Yasmeen, Mussarat

2018-04-01

Conventionally, cardiac MR image analysis is done manually. Automatic examination for analyzing images can replace the monotonous tasks of massive amounts of data to analyze the global and regional functions of the cardiac left ventricle (LV). This task is performed using MR images to calculate the analytic cardiac parameter like end-systolic volume, end-diastolic volume, ejection fraction, and myocardial mass, respectively. These analytic parameters depend upon genuine delineation of epicardial, endocardial, papillary muscle, and trabeculations contours. In this paper, we propose an automatic segmentation method using the sum of absolute differences technique to localize the left ventricle. Blind morphological operations are proposed to segment and detect the LV contours of the epicardium and endocardium, automatically. We test the benchmark Sunny Brook dataset for evaluation of the proposed work. Contours of epicardium and endocardium are compared quantitatively to determine contour's accuracy and observe high matching values. Similarity or overlapping of an automatic examination to the given ground truth analysis by an expert are observed with high accuracy as with an index value of 91.30% . The proposed method for automatic segmentation gives better performance relative to existing techniques in terms of accuracy.

Electron Emission from Amorphous Solid Water Induced by Passage of Energetic Protons and Fluorine Ions

PubMed Central

Toburen, L. H.; McLawhorn, S. L.; McLawhorn, R. A.; Carnes, K. D.; Dingfelder, M.; Shinpaugh, J. L.

2013-01-01

Absolute doubly differential electron emission yields were measured from thin films of amorphous solid water (ASW) after the transmission of 6 MeV protons and 19 MeV (1 MeV/nucleon) fluorine ions. The ASW films were frozen on thin (1-μm) copper foils cooled to approximately 50 K. Electrons emitted from the films were detected as a function of angle in both the forward and backward direction and as a function of the film thickness. Electron energies were determined by measuring the ejected electron time of flight, a technique that optimizes the accuracy of measuring low-energy electron yields, where the effects of molecular environment on electron transport are expected to be most evident. Relative electron emission yields were normalized to an absolute scale by comparison of the integrated total yields for proton-induced electron emission from the copper substrate to values published previously. The absolute doubly differential yields from ASW are presented along with integrated values, providing single differential and total electron emission yields. These data may provide benchmark tests of Monte Carlo track structure codes commonly used for assessing the effects of radiation quality on biological effectiveness. PMID:20681805

Possibilities and limitations of rod-beam theories. [nonlinear distortion tensor and nonlinear stress tensors

NASA Technical Reports Server (NTRS)

Peterson, D.

1979-01-01

Rod-beam theories are founded on hypotheses such as Bernouilli's suggesting flat cross-sections under deformation. These assumptions, which make rod-beam theories possible, also limit the accuracy of their analysis. It is shown that from a certain order upward terms of geometrically nonlinear deformations contradict the rod-beam hypotheses. Consistent application of differential geometry calculus also reveals differences from existing rod theories of higher order. These differences are explained by simple examples.

Kinetics of Exocytosis Is Faster in Cones Than in Rods

PubMed Central

Rabl, Katalin; Cadetti, Lucia; Thoreson, Wallace B.

2006-01-01

Cone-driven responses of second-order retinal neurons are considerably faster than rod-driven responses. We examined whether differences in the kinetics of synaptic transmitter release from rods and cones may contribute to differences in postsynaptic response kinetics. Exocytosis from rods and cones was triggered by membrane depolarization and monitored in two ways: (1) by measuring EPSCs evoked in second-order neurons by depolarizing steps applied to presynaptic rods or cones during simultaneous paired whole-cell recordings or (2) by direct measurements of exocytotic increases in membrane capacitance. The kinetics of release was assessed by varying the length of the depolarizing test step. Both measures of release revealed two kinetic components to the increase in exocytosis as a function of the duration of a step depolarization. In addition to slow sustained components in both cell types, the initial fast component of exocytosis had a time constant of <5 ms in cones, >10-fold faster than that of rods. Rod/cone differences in the kinetics of release were substantiated by a linear correlation between depolarization-evoked capacitance increases and EPSC charge transfer. Experiments on isolated rods indicate that the slower kinetics of exocytosis from rods was not a result of rod–rod coupling. The initial rapid release of vesicles from cones can shape the postsynaptic response and may contribute to the faster responses of cone-driven cells observed at light offset. PMID:15872111

Effect of compressibility on the hypervelocity penetration

NASA Astrophysics Data System (ADS)

Song, W. J.; Chen, X. W.; Chen, P.

2018-02-01

We further consider the effect of rod strength by employing the compressible penetration model to study the effect of compressibility on hypervelocity penetration. Meanwhile, we define different instances of penetration efficiency in various modified models and compare these penetration efficiencies to identify the effects of different factors in the compressible model. To systematically discuss the effect of compressibility in different metallic rod-target combinations, we construct three cases, i.e., the penetrations by the more compressible rod into the less compressible target, rod into the analogously compressible target, and the less compressible rod into the more compressible target. The effects of volumetric strain, internal energy, and strength on the penetration efficiency are analyzed simultaneously. It indicates that the compressibility of the rod and target increases the pressure at the rod/target interface. The more compressible rod/target has larger volumetric strain and higher internal energy. Both the larger volumetric strain and higher strength enhance the penetration or anti-penetration ability. On the other hand, the higher internal energy weakens the penetration or anti-penetration ability. The two trends conflict, but the volumetric strain dominates in the variation of the penetration efficiency, which would not approach the hydrodynamic limit if the rod and target are not analogously compressible. However, if the compressibility of the rod and target is analogous, it has little effect on the penetration efficiency.

Method of measuring a profile of the density of charged particles in a particle beam

DOEpatents

Hyman, L.G.; Jankowski, D.J.

1975-10-01

A profile of the relative density of charged particles in a beam is obtained by disposing a number of rods parallel to each other in a plane perpendicular to the beam and shadowing the beam. A second number of rods is disposed perpendicular to the first rods in a plane perpendicular to the beam and also shadowing the beam. Irradiation of the rods by the beam of charged particles creates radioactive isotopes in a quantity proportional to the number of charged particles incident upon the rods. Measurement of the radioactivity of each of the rods provides a measure of the quantity of radioactive material generated thereby and, together with the location of the rods, provides information sufficient to identify a profile of the density of charged particles in the beam.

Fabrication of light water reactor tritium targets

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

Pilger, J.P.

1991-11-01

The mission of the Fabrication Development Task of the Tritium Target Development Project is: to produce a documented technology basis, including specifications and procedures for target rod fabrication; to demonstrate that light water tritium targets can be manufactured at a rate consistent with tritium production requirements; and to develop quality control methods to evaluate target rod components and assemblies, and establish correlations between evaluated characteristics and target rod performance. Many of the target rod components: cladding tubes, end caps, plenum springs, etc., have similar counterparts in LWR fuel rods. High production rate manufacture and inspection of these components has beenmore » adequately demonstrated by nuclear fuel rod manufacturers. This summary describes the more non-conventional manufacturing processes and inspection techniques developed to fabricate target rod components whose manufacturability at required production rates had not been previously demonstrated.« less

A prospective randomized controlled trial comparing early postoperative complications in patients undergoing loop colostomy with and without a stoma rod.

PubMed

Franklyn, J; Varghese, G; Mittal, R; Rebekah, G; Jesudason, M R; Perakath, B

2017-07-01

A stoma rod or bridge has been traditionally placed under the bowel loop while constructing a loop colostomy. This is believed to prevent stomal retraction and provide better faecal diversion. However, the rod can cause complications such as mucosal congestion, oedema and necrosis. This single-centre prospective randomized controlled trial compared outcomes after creation of loop colostomy with and without a supporting stoma rod. The primary outcome studied was stoma retraction rate; other stoma-related complications were studied as secondary outcomes. One hundred and fifty-one patients were randomly allotted to one of two arms, colostomy with or without a supporting rod. Postoperative complications such as retraction, mucocutaneous separation, congestion and re-exploration for stoma-related complications were recorded. There was no difference in the stoma retraction rate between the two arms (8.1% in the rod arm and 6.6% in the no-rod arm; P = 0.719). Stomal necrosis (10.7% vs 1.3%; P = 0.018), oedema (23% vs 3.9%; P = 0.001), congestion (20.3% vs 2.6%; P = 0.001) and re-admission rates (8.5% vs 0%; P = 0.027) were significantly increased in the arm randomized to the rod. The stoma rod does not prevent stomal retraction. However, complication rates are significantly higher when a stoma rod is used. Routine use of a stoma rod for construction of loop colostomy can be avoided. Colorectal Disease © 2017 The Association of Coloproctology of Great Britain and Ireland.

Microporous rod metal-organic frameworks with diverse Zn/Cd-triazolate ribbons as secondary building units for CO2 uptake and selective adsorption of hydrocarbons.

PubMed

Zhang, Jian-Wei; Hu, Man-Cheng; Li, Shu-Ni; Jiang, Yu-Cheng; Zhai, Quan-Guo

2017-01-17

The synthetic design of new porous open-framework materials with pre-designed pore properties for desired applications such as gas adsorption and separation remains challenging. We proposed one such class of materials, rod metal-organic frameworks (rod MOFs), which can be tuned by using rod secondary building units (rod SBUs) with different geometrical and chemical features. Our approach takes advantage of the readily accessible metal-triazolate 1-D motifs as rod SBUs to combine with dicarboxylate ligands to prepare target rod MOFs. Herein we report three such metal-triazolate-dicarboxylate frameworks (SNNU-21, -22 and -23). During the formation of these three MOFs, Cd or Zn ions are firstly connected by 1,2,4-triazole through the N1,N2,N4-mode to form 1-D metal-organic ribbon-like rod SBUs, which further joint four adjacent rod SBUs via eight BDC linkers to give 3-D microporous frameworks. However, tuned by the different NH 2 groups from metal-triazolate rod SBUs, different space groups, pore sizes and shapes are observed for SNNU-21-23. All of these rod MOFs show not only remarkable CO 2 uptake capacity, but also high CO 2 over CH 4 and C 2 -hydrocarbons over CH 4 selectivity under ambient conditions. Specially, SNNU-23 exhibits a very high isosteric heat of adsorption (Q st ) for C 2 H 2 (62.2 kJ mol -1 ), which outperforms the values of all MOF materials reported to date including the famous MOF-74-Co.

Increased visual sensitivity following periods of dim illumination.

PubMed

McKeown, Alex S; Kraft, Timothy W; Loop, Michael S

2015-02-19

We measured changes in the sensitivity of the human rod pathway by testing visual reaction times before and after light adaptation. We targeted a specific range of conditioning light intensities to see if a physiological adaptation recently discovered in mouse rods is observable at the perceptual level in humans. We also measured the noise spectrum of single mouse rods due to the importance of the signal-to-noise ratio in rod to rod bipolar cell signal transfer. Using the well-defined relationship between stimulus intensity and reaction time (Piéron's law), we measured the reaction times of eight human subjects (ages 24-66) to scotopic test flashes of a single intensity before and after the presentation of a 3-minute background. We also made recordings from single mouse rods and processed the cellular noise spectrum before and after similar conditioning exposures. Subject reaction times to a fixed-strength stimulus were fastest 5 seconds after conditioning background exposure (79% ± 1% of the preconditioning mean, in darkness) and were significantly faster for the first 12 seconds after background exposure (P < 0.01). During the period of increased rod sensitivity, the continuous noise spectrum of individual mouse rods was not significantly increased. A decrease in human reaction times to a dim flash after conditioning background exposure may originate in rod photoreceptors through a transient increase in the sensitivity of the phototransduction cascade. There is no accompanying increase in rod cellular noise, allowing for reliable transmission of larger rod signals after conditioning exposures and the observed increase in perceptual sensitivity. Copyright 2015 The Association for Research in Vision and Ophthalmology, Inc.

Mechanisms that limit the light stimulus frequency following through the APB sensitive and insensitive rod Off-pathways

PubMed Central

Bai, Xia; Zhu, Junling; Yang, Jinnan; Savoie, Brian T.; Wang, Guo-Yong

2009-01-01

In the retina, rod signal pathways process scotopic visual information. Light decrements are mediated by two distinct groups of rod pathways in the dark adapted retina that can be differentiated on the basis of their sensitivity to the glutamate agonist DL-2-amino-4-phosphonobutyric acid (APB). We have found that the APB sensitive and insensitive rod Off-pathways signal different light decrement information: the APB sensitive rod Off-pathway conveys slow and low frequency light signals, whereas the APB insensitive rod Off-pathways mediate fast and high frequency light signals (Wang, 2006). However, the mechanisms which limit the frequency following through the APB sensitive and insensitive rod Off-pathways remain unknown. In the current study, whole-cell patch-clamp recordings were made from ganglion cells in dark and light adapted mouse retina to identify the mechanisms that limit the frequency following through the APB sensitive and insensitive rod Off-pathways. The results showed that the sites from AII amacrine cells to Off cone bipolar cells are the major mechanisms that limit the frequency following through the APB sensitive rod Off-pathway. In the APB insensitive rod Off-pathways, rods themselves limited the frequency following through these pathways. Moreover, ganglion cells were able to follow higher frequencies under photopic conditions than under scotopic conditions. The Off responses followed lower frequencies than On responses under photopic conditions. This finding was observed in cells that yielded On or Off responses only as well as in On-Off cells. PMID:19406212

78 FR 12718 - Certain Steel Threaded Rod From the People's Republic of China: Affirmative Final Determination...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-02-25

... DEPARTMENT OF COMMERCE International Trade Administration [A-570-932] Certain Steel Threaded Rod... Preliminary Determination of the circumvention inquiry concerning the antidumping duty order on certain steel threaded rod (``steel threaded rod'') from the People's Republic of China (``PRC'').\\1\\ The period of...

Xenon-induced power oscillations in a generic small modular reactor

NASA Astrophysics Data System (ADS)

Kitcher, Evans Damenortey

As world demand for energy continues to grow at unprecedented rates, the world energy portfolio of the future will inevitably include a nuclear energy contribution. It has been suggested that the Small Modular Reactor (SMR) could play a significant role in the spread of civilian nuclear technology to nations previously without nuclear energy. As part of the design process, the SMR design must be assessed for the threat to operations posed by xenon-induced power oscillations. In this research, a generic SMR design was analyzed with respect to just such a threat. In order to do so, a multi-physics coupling routine was developed with MCNP/MCNPX as the neutronics solver. Thermal hydraulic assessments were performed using a single channel analysis tool developed in Python. Fuel and coolant temperature profiles were implemented in the form of temperature dependent fuel cross sections generated using the SIGACE code and reactor core coolant densities. The Power Axial Offset (PAO) and Xenon Axial Offset (XAO) parameters were chosen to quantify any oscillatory behavior observed. The methodology was benchmarked against results from literature of startup tests performed at a four-loop PWR in Korea. The developed benchmark model replicated the pertinent features of the reactor within ten percent of the literature values. The results of the benchmark demonstrated that the developed methodology captured the desired phenomena accurately. Subsequently, a high fidelity SMR core model was developed and assessed. Results of the analysis revealed an inherently stable SMR design at beginning of core life and end of core life under full-power and half-power conditions. The effect of axial discretization, stochastic noise and convergence of the Monte Carlo tallies in the calculations of the PAO and XAO parameters was investigated. All were found to be quite small and the inherently stable nature of the core design with respect to xenon-induced power oscillations was confirmed. Finally, a preliminary investigation into excess reactivity control options for the SMR design was conducted confirming the generally held notion that existing PWR control mechanisms can be used in iPWR SMRs with similar effectiveness. With the desire to operate the SMR under the boron free coolant condition, erbium oxide fuel integral burnable absorber rods were identified as a possible means to retain the dispersed absorber effect of soluble boron in the reactor coolant in replacement.

A simultaneous spin/eject mechanism for aerospace payloads

NASA Technical Reports Server (NTRS)

Palmer, G. D.; Banks, T. N.

1976-01-01

A simultaneous spin/eject mechanism was developed for aerospace applications requiring a compact, passive device which would accommodate payload support and controlled-release functions, and which would provide a highly accurate spin-ejection motion to the payload. The mechanism satisfied the requirements and is adaptable to other deployment applications.

Pulsed ultrasonic stir welding method

NASA Technical Reports Server (NTRS)

Ding, R. Jeffrey (Inventor)

2013-01-01

A method of performing ultrasonic stir welding uses a welding head assembly to include a plate and a rod passing through the plate. The rod is rotatable about a longitudinal axis thereof. In the method, the rod is rotated about its longitudinal axis during a welding operation. During the welding operation, a series of on-off ultrasonic pulses are applied to the rod such that they propagate parallel to the rod's longitudinal axis. At least a pulse rate associated with the on-off ultrasonic pulses is controlled.

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.

13. SOUTHEAST TO SUCKER ROD WORK BENCH AND WOODEN SUCKER ...

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

13. SOUTHEAST TO SUCKER ROD WORK BENCH AND WOODEN SUCKER ROD STORAGE RACKS ALONG EAST WALL OF FACTORY INTERIOR. AT THIS BENCH WORKERS RIVETED THREADED WROUGHT IRON CONNECTORS TO THE ENDS OF 20' LONG WOODEN SUCKER RODS (THE RODS WHICH EXTEND DOWNWARD IN THE WELL FROM THE GROUND SURFACE TO PISTON DISPLACEMENT PUMPS WHICH ACTUALLY ELEVATE WATER TO THE SURFACE). ROZNOR HEATER AT THE FAR RIGHT WAS ADDED CIRCA 1960. - Kregel Windmill Company Factory, 1416 Central Avenue, Nebraska City, Otoe County, NE

Dynamic Rod Worth Measurement

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

Chao, Y.A.; Chapman, D.M.; Hill, D.J.

2000-12-15

The dynamic rod worth measurement (DRWM) technique is a method of quickly validating the predicted bank worth of control rods and shutdown rods. The DRWM analytic method is based on three-dimensional, space-time kinetic simulations of the rapid rod movements. Its measurement data is processed with an advanced digital reactivity computer. DRWM has been used as the method of bank worth validation at numerous plant startups with excellent results. The process and methodology of DRWM are described, and the measurement results of using DRWM are presented.

Remote chance of recontact

NASA Technical Reports Server (NTRS)

Elkin, D.; Abeyagunawardene, S.; Defazio, R.

1988-01-01

The ejection of appendages with uncertain drag characteristics presents a concern for eventual recontact. Recontact shortly after release can be prevented by avoiding ejection in a plane perpendicular to the velocity. For ejection tangential to the orbit, the likelihood of recontact within a year is high in the absence of drag and oblateness. The optimum direction of ejection of the thermal shield cable and an overestimate of the recontact probability are determined for the Cosmic Background Explorer (COBE) mission when drag, oblateness, and solar/lunar perturbations are present. The probability is small but possibly significant.

Simulation of 'pathologic' changes in ICG waveforms resulting from superposition of the 'preejection' and ejection waves induced by left ventricular contraction

NASA Astrophysics Data System (ADS)

Ermishkin, V. V.; Kolesnikov, V. A.; Lukoshkova, E. V.; Sonina, R. S.

2013-04-01

The impedance cardiography (ICG) is widely used for beat-to-beat noninvasive evaluation of the left ventricular stroke volume and contractility. It implies the correct determination of the ejection start and end points and the amplitudes of certain peaks in the differentiated impedance cardiogram. An accurate identification of ejection onset by ICG is often problematic, especially in the cardiologic patients, due to peculiar waveforms. Using a simple theoretical model, we tested the hypothesis that two major processes are responsible for the formation of impedance systolic wave: (1) the changes in the heart geometry and surrounding vessels produced by ventricular contraction, which occur during the isovolumic phase and precede ejection, and (2) expansion of aorta and adjacent arteries during the ejection phase. The former process initiates the preejection wave WpE and the latter triggers the ejection wave WEj. The model predicts a potential mechanism of generating the abnormal shapes of dZ/dt due to the presence of preejection waves and explains the related errors in ICG time and amplitude parameters. An appropriate decomposition method is a promising way to avoid the masking effects of these waves and a further step to correct determination of the onset of ejection and the corresponding peak amplitudes from 'pathologically shaped' ICG signals.

Investigation on occupant ejection in high severity rear impact based on post mortem human subject sled tests.

PubMed

Petit, Philippe; Luet, Carole; Potier, Pascal; Vallancien, Guy

2011-11-01

Occupant protection in rear impact involves two competing challenges. On one hand, allowing a deformation of the seat would act as an energy absorber in low severity impacts and would consequently decrease the risk of neck injuries. However, on the other hand, large deformations of the seat may increase the likelihood of occupant ejection in high severity cases. Green et al. 1987 analyzed a total of 919 accidents in Great Britain. They found that occupant ejection resulted in a risk of severe injuries and fatalities between 3.6 and 4.5 times higher than those cases where no ejection was observed. The sample included single front, side and rear impacts as well as multiple impacts and rollover. The rate of belt use in the sample was 50%. While this analysis included all forms of impact scenarios, nevertheless, it highlights the relative injury severity of occupant ejection. Extensive literature search has found no full-scale rear impact tests involving Post Mortem Human Subjects (PMHS) conducted in a laboratory environment and resulting in ejection. This paper describes a total of 10 sled tests conducted on 3 belted PMHS using a simplified seat design composed of rigid plates assembled such that the angular and linear stiffness of the seatback (including the foam) was modeled. The initial angular position and the range of motion of the seatback, the size of the PMHS, the slack length of the seatbelt, the angular stiffness of the seatback, and the use of headrest were varied in the test matrix while the pulse was kept constant (triangular acceleration with a peak of 17 G at 30 ms and a duration of 95 ms). In the test series, the tests were not run randomly but the likelihood of occupant ejection was increased systematically until ejection occurred. PMHS seat ejection was observed only for the 95th percentile, initially positioned with a seatback angle relative to the vertical equal to 22°, a range of seatback angular motion equal to 44° and no headrest. Repeating the test under the same conditions but with the pretentionner fired did not prevent the ejection. In addition, the 50th percentile belted specimen were not observed to sustain rearward seat ejection under realistic conditions including the use of head-rest.

Biomineralization of uniform gallium oxide rods with cellular compatibility.

PubMed

Yan, Danhong; Yin, Guangfu; Huang, Zhongbing; Liao, Xiaoming; Kang, Yunqing; Yao, Yadong; Hao, Baoqing; Gu, Jianwen; Han, Dong

2009-07-20

Monodispersed single crystalline alpha-GaOOH rods coated by silk fibroin (SF) have been prepared via a facile biomineralization process in the template of SF peptide. The carbon-coated alpha-Ga(2)O(3) and beta-Ga(2)O(3) rods are obtained by thermal treatment of the alpha-GaOOH rods at 600 and 800 degrees C, respectively. In vitro cytotoxicity studies of these gallium oxide rods showed no significant effect leading to restraint of cell proliferation of L929, Hela, and HaCat cells in less than 0.1 mg/mL prepared rods. On the basis of their excellent luminescence emission properties and cellular compatibilities, possible applications for bio-optoelectronic devices can be envisioned.

Vortex Noise from Rotating Cylindrical Rods

NASA Technical Reports Server (NTRS)

Stowell, E Z; Deming, A F

1935-01-01

A series of round rods of the some diameter were rotated individually about the mid-point of each rod. Vortices are shed from the rods when in motion, giving rise to the emission of sound. With the rotating system placed in the open air, the distribution of sound in space, the acoustical power output, and the spectral distribution have been studied. The frequency of emission of vortices from any point on the rod is given by the formula von Karman. From the spectrum estimates are made of the distribution of acoustical power along the rod, the amount of air concerned in sound production, the "equivalent size" of the vortices, and the acoustical energy content for each vortex.

Method of making single crystal fibers

NASA Technical Reports Server (NTRS)

Westfall, Leonard J. (Inventor)

1990-01-01

Single crystal fibers are made from miniature extruded ceramic feed rods. A decomposable binder is mixed with powders to inform a slurry which is extruded into a small rod which may be sintered, either in air or in vacuum, or it may be used in the extruded and dried condition. A pair of laser beams focuses onto the tip of the rod to melt it thereby forming a liquid portion. A single crystal seed fiber of the same material as the feed rod contacts this liquid portion to establish a zone of liquid material between the feed rod and the single crystal seed fiber. The feed rod and the single crystal feed fiber are moved at a predetermined speed to solidify the molten zone onto the seed fiber while simultaneously melting additional feed rod. In this manner a single crystal fiber is formed from the liquid portion.

Compact Hybrid Laser Rod and Laser System

NASA Technical Reports Server (NTRS)

Pierrottet, Diego F. (Inventor); Busch, George E. (Inventor); Amzajerdian, Farzin (Inventor)

2017-01-01

A hybrid fiber rod includes a fiber core and inner and outer cladding layers. The core is doped with an active element. The inner cladding layer surrounds the core, and has a refractive index substantially equal to that of the core. The outer cladding layer surrounds the inner cladding layer, and has a refractive index less than that of the core and inner cladding layer. The core length is about 30 to 2000 times the core diameter. A hybrid fiber rod laser system includes an oscillator laser, modulating device, the rod, and pump laser diode(s) energizing the rod from opposite ends. The rod acts as a waveguide for pump radiation but allows for free-space propagation of laser radiation. The rod may be used in a laser resonator. The core length is less than about twice the Rayleigh range. Degradation from single-mode to multi-mode beam propagation is thus avoided.

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

Alexeev, A. V.; Maltseva, D. V.; Ivanov, V. A., E-mail: ivanov@polly.phys.msu.ru

We study force-extension curves of a single semiflexible chain consisting of several rigid rods connected by flexible spacers. The atomic force microscopy and laser optical or magnetic tweezers apparatus stretching these rod-coil macromolecules are discussed. In addition, the stretching by external isotropic force is analyzed. The main attention is focused on computer simulation and analytical results. We demonstrate that the force-extension curves for rod-coil chains composed of two or three rods of equal length differ not only quantitatively but also qualitatively in different probe methods. These curves have an anomalous shape for a chain of two rods. End-to-end distributions ofmore » rod-coil chains are calculated by Monte Carlo method and compared with analytical equations. The influence of the spacer’s length on the force-extension curves in different probe methods is analyzed. The results can be useful for interpreting experiments on the stretching of rod-coil block-copolymers.« less

Spontaneous membrane formation and self-encapsulation of active rods in an inhomogeneous motility field

NASA Astrophysics Data System (ADS)

Grauer, Jens; Löwen, Hartmut; Janssen, Liesbeth M. C.

2018-02-01

We study the collective dynamics of self-propelled rods in an inhomogeneous motility field. At the interface between two regions of constant but different motility, a smectic rod layer is spontaneously created through aligning interactions between the active rods, reminiscent of an artificial, semipermeable membrane. This "active membrane" engulfes rods which are locally trapped in low-motility regions and thereby further enhances the trapping efficiency by self-organization, an effect which we call "self-encapsulation." Our results are gained by computer simulations of self-propelled rod models confined on a two-dimensional planar or spherical surface with a stepwise constant motility field, but the phenomenon should be observable in any geometry with sufficiently large spatial inhomogeneity. We also discuss possibilities to verify our predictions of active-membrane formation in experiments of self-propelled colloidal rods and vibrated granular matter.

HWCTR CONTROL ROD AND SAFETY ROD DRIVE SYSTEMS

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

Kale, S.H.

1963-07-01

The Heavy Water Components Test Reactor (HWCTR) is a pressurized, D/sub 2/O reactor designed for operation up to 70 Mw at 1500 psig and 3l5 deg C. It has 18 control rods and six safety rods, each driven by an electric motor through a rack and pinion gear train. Racks, pinions, and bearings are located inside individual pressure housings that are penetrated by means of floating ring labyrinth seals. The drives are mounted on the reactor vessel top head. Safety rods have electromagnetic clutches and fall into the reactor when scrammed. The reliability and performance of the rod drives aremore » very good. Seal leakage is well within design limits. Recent inspections of seals and control rod plants showed no evidence of crud buildup or stress corrosion cracking of type 17- 4PH'' stainless steel components. (auth)« less

21 CFR 876.4270 - Colostomy rod.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Colostomy rod. 876.4270 Section 876.4270 Food and... GASTROENTEROLOGY-UROLOGY DEVICES Surgical Devices § 876.4270 Colostomy rod. (a) Identification. A colostomy rod is a device used during the loop colostomy procedure. A loop of colon is surgically brought out through...

77 FR 3231 - Certain Stainless Steel Wire Rods From India: Continuation of Antidumping Duty Order

Federal Register 2010, 2011, 2012, 2013, 2014

2012-01-23

... DEPARTMENT OF COMMERCE International Trade Administration [A-533-808] Certain Stainless Steel Wire... antidumping duty order on certain stainless steel wire rods from India would likely lead to continuation or... reviews of the antidumping duty order on certain stainless steel wire rods (``wire rods'') from India,\\1...

75 FR 32503 - Stainless Steel Wire Rod From Italy, Japan, Korea, Spain, and Taiwan

Federal Register 2010, 2011, 2012, 2013, 2014

2010-06-08

...)] Stainless Steel Wire Rod From Italy, Japan, Korea, Spain, and Taiwan Determinations On the basis of the... revocation of the antidumping duty orders on stainless steel wire rod from Italy, Japan, Korea, Spain, and... USITC Publication 4154 (May 2010), entitled Stainless Steel Wire Rod from Italy, Japan, Korea, Spain...

77 FR 37793 - Airworthiness Directives; the Boeing Company Airplanes

Federal Register 2010, 2011, 2012, 2013, 2014

2012-06-25

... proposed to require installing new structural members in and new tie rod(s) and attach fittings on the left.... ACTION: Final rule. SUMMARY: We are adopting a new airworthiness directive (AD) for certain the Boeing... forward load. This AD requires installing new structural members, tie rod(s), and attach fittings on the...

Granular materials interacting with thin flexible rods

NASA Astrophysics Data System (ADS)

Neto, Alfredo Gay; Campello, Eduardo M. B.

2017-04-01

In this work, we develop a computational model for the simulation of problems wherein granular materials interact with thin flexible rods. We treat granular materials as a collection of spherical particles following a discrete element method (DEM) approach, while flexible rods are described by a large deformation finite element (FEM) rod formulation. Grain-to-grain, grain-to-rod, and rod-to-rod contacts are fully permitted and resolved. A simple and efficient strategy is proposed for coupling the motion of the two types (discrete and continuum) of materials within an iterative time-stepping solution scheme. Implementation details are shown and discussed. Validity and applicability of the model are assessed by means of a few numerical examples. We believe that robust, efficiently coupled DEM-FEM schemes can be a useful tool to the simulation of problems wherein granular materials interact with thin flexible rods, such as (but not limited to) bombardment of grains on beam structures, flow of granular materials over surfaces covered by threads of hair in many biological processes, flow of grains through filters and strainers in various industrial segregation processes, and many others.

Parallel Operation of Multiple Closely Spaced Small Aspect Ratio Rod Pinches

DOE PAGES

Harper-Slaboszewicz, Victor J.; Leckbee, Joshua; Bennett, Nichelle; ...

2014-12-10

A series of simulations and experiments to resolve questions about the operation of arrays of closely spaced small aspect ratio rod pinches has been performed. Design and post-shot analysis of the experimental results are supported by 3D particle-in-cell simulations. Both simulations and experiments support these conclusions. Penetration of current to the interior of the array appears to be efficient, as the current on the center rods is essentially equal to the current on the outer rods. Current loss in the feed due to the formation of magnetic nulls was avoided in these experiments by design of the feed surface ofmore » the cathode and control of the gap to keep the electric fields on the cathode below the emission threshold. Some asymmetry in the electron flow to the rod was observed, but the flow appeared to symmetrize as it reached the end of the rod. Interaction between the rod pinches can be controlled to allow the stable and consistent operation of arrays of rod pinches.« less

DEVICE FOR CONTROLLING INSERTION OF ROD

DOEpatents

Beaty, B.J.

1958-10-14

A device for rapidly inserting a safety rod into a nuclear reactor upon a given signal or in the event of a power failure in order to prevent the possibility of extensive damage caused by a power excursion is described. A piston is slidably mounted within a vertical cylinder with provision for an electromagnetic latch at the top of the cylinder. This assembly, with a safety rod attached to the piston, is mounted over an access port to the core region of the reactor. The piston is normally latched at the top of the cylinder with the safety rod clear of the core area, however, when the latch is released, the piston and rod drop by their own weight to insert the rod. Vents along the side of the cylinder permit the escape of the air entrapped under the piston over the greater part of the distance, however, at the end of the fall the entrapped air is compressed thereby bringing the safety rod gently to rest, thus providing for a rapid automatic insertion of the rod with a minimum of structural shock.

Analysis of enamel rod end patterns on tooth surface for personal identification--ameloglyphics.

PubMed

Manjunath, Krishnappa; Sivapathasundharam, Balasundharam; Saraswathi, Thillai R

2012-05-01

Ameloglyphics is the study of enamel rod end patterns on a tooth surface. Our aim was to study the in vivo analysis of enamel rod end patterns on tooth surfaces for personal identification. In this study, the maxillary left canine and 1st premolar of 30 men and 30 women were included. The cellulose acetate peel technique was used to record enamel rod endings on tooth surfaces. Photomicrographs of the acetate peel imprint were subjected to VeriFinger Standard SDK v5.0 software for obtaining enamel rod end patterns. All 120 enamel rod end patterns were subjected to visual analysis and biometric analysis. Biometric analysis revealed that the enamel rod end pattern is unique for each tooth in an individual. It shows both intra- and interindividual variation. Enamel rod end patterns were unique between the male and female subjects. Visual analysis showed that wavy branched subpattern was the predominant subpattern observed among examined teeth. Hence, ameloglyphics is a reliable technique for personal identification. © 2012 American Academy of Forensic Sciences.

Depletion of calcium stores regulates calcium influx and signal transmission in rod photoreceptors

PubMed Central

Szikra, Tamas; Cusato, Karen; Thoreson, Wallace B; Barabas, Peter; Bartoletti, Theodore M; Krizaj, David

2008-01-01

Tonic synapses are specialized for sustained calcium entry and transmitter release, allowing them to operate in a graded fashion over a wide dynamic range. We identified a novel plasma membrane calcium entry mechanism that extends the range of rod photoreceptor signalling into light-adapted conditions. The mechanism, which shares molecular and physiological characteristics with store-operated calcium entry (SOCE), is required to maintain baseline [Ca2+]i in rod inner segments and synaptic terminals. Sustained Ca2+ entry into rod cytosol is augmented by store depletion, blocked by La3+ and Gd3+ and suppressed by organic antagonists MRS-1845 and SKF-96365. Store depletion and the subsequent Ca2+ influx directly stimulated exocytosis in terminals of light-adapted rods loaded with the activity-dependent dye FM1–43. Moreover, SOCE blockers suppressed rod-mediated synaptic inputs to horizontal cells without affecting presynaptic voltage-operated Ca2+ entry. Silencing of TRPC1 expression with small interference RNA disrupted SOCE in rods, but had no effect on cone Ca2+ signalling. Rods were immunopositive for TRPC1 whereas cone inner segments immunostained with TRPC6 channel antibodies. Thus, SOCE modulates Ca2+ homeostasis and light-evoked neurotransmission at the rod photoreceptor synapse mediated by TRPC1. PMID:18755743

Reflectance Spectra of Peacock Feathers and the Turning Angles of Melanin Rods in Barbules.

PubMed

Okazaki, Toshio

2018-02-01

I analyzed the association between the reflectance spectra and melanin rod arrangement in barbules of the eyespot of peacock feathers. The reflectance spectra from the yellow-green feather of the eyespot indicated double peaks of 430 and 540 nm. The maximum reflectance spectrum of the blue feather was 480 nm, and that of the dark blue feather was 420 nm. The reflectance spectra from brown feathers indicated double peaks of 490 and 610 nm. Transmission electron microscopic analysis confirmed that melanin rods were arranged fanwise in the outer layer toward the barbule tips. In addition, using polarized light microscope, I attempted to determine whether the turning angles of melanin rods in the barbules reflected different colors. The turning angle of the polarizing axis of the barbules was supported by that of the melanin rods, observed using transmission electron microscopic images. To compare the turning angle of melanin rods in the respective barbules, I calculated the opening width of the fanwise melanin rods by dividing the width of the barbules by the turning angle of the polarizing axis of barbules and obtained a positive correlation between the reflectance spectra and opening width of the fanwise melanin rods. Moreover, the widely spreading reflection from the barbules may occur because of the fanwise melanin rod arrangement.

Effect of repeated sterilization by different methods on strength of carbon fiber rods used in external fixator systems.

PubMed

Unal, Omer Kays; Poyanli, Oguz Sukru; Unal, Ulku Sur; Mutlu, Hasan Huseyin; Ozkut, Afsar Timucin; Esenkaya, Irfan

2018-05-16

We set out to reveal the effects of repeated sterilization, using different methods, on the carbon fiber rods of external fixator systems. We used a randomized set of forty-four unused, unsterilized, and identical carbon fiber rods (11 × 200 mm), randomly assigned to two groups: unsterilized (US) (4 rods) and sterilized (40 rods). The sterilized rods were divided into two groups, those sterilized in an autoclave (AC) and by hydrogen peroxide (HP). These were further divided into five subgroups based on the number of sterilization repetition to which the fibers were subjected (25-50-75-100-200). A bending test was conducted to measure the maximum bending force (MBF), maximum deflection (MD), flexural strength (FS), maximum bending moment (MBM) and bending rigidity (BR). We also measured the surface roughness of the rods. An increase in the number of sterilization repetition led to a decrease in MBF, MBM, FS, BR, but increased MD and surface roughness (p < 0.01). The effect of the number of sterilization repetition was more prominent in the HP group. This study revealed that the sterilization method and number of sterilization repetition influence the strength of the carbon fiber rods. Increasing the number of sterilization repetition degrades the strength and roughness of the rods.

Modification of Shirt Buttons for Retrospective Radiation Dosimetry after a Radiological Event

PubMed Central

Marino, Stephen A.; Johnson, Gary W.; Schiff, Peter B.; Brenner, David J.

2010-01-01

Preliminary results are presented for a personal radiation dosimeter in the form of a clothing button to provide gamma-ray dose estimation for clinically significant external radiation exposures to the general public due to a radiological incident, such as a Radiological Dispersal Device. Rods of thermoluminescent material (LiF:Mg,Ti and LiF:Mg,Cu,P) were encapsulated in plastic “buttons”, attached to shirts, and subjected to three cycles of home or commercial laundering or dry cleaning, including ironing or pressing. The buttons were subsequently exposed to doses of 137Cs gamma rays ranging from 0.75 to 8.2 Gy. The rods were removed from the buttons and their light output compared to their responses when bare or to the responses of a set of calibration rods of the same type and from the same manufacturer. In all three of the comparisons for LiF:Mg,Ti rods the relative responses of the rods in buttons changed by 2-6% relative to the same rods before cleaning. In both comparisons for LiF:Mg,Cu,P rods, the response of laundered rods was 1-3% lower than for the same rods before cleaning. Both these materials are potential candidates for button dosimeters. PMID:21451325

Noninvasive imaging of the human rod photoreceptor mosaic using a confocal adaptive optics scanning ophthalmoscope

PubMed Central

Dubra, Alfredo; Sulai, Yusufu; Norris, Jennifer L.; Cooper, Robert F.; Dubis, Adam M.; Williams, David R.; Carroll, Joseph

2011-01-01

The rod photoreceptors are implicated in a number of devastating retinal diseases. However, routine imaging of these cells has remained elusive, even with the advent of adaptive optics imaging. Here, we present the first in vivo images of the contiguous rod photoreceptor mosaic in nine healthy human subjects. The images were collected with three different confocal adaptive optics scanning ophthalmoscopes at two different institutions, using 680 and 775 nm superluminescent diodes for illumination. Estimates of photoreceptor density and rod:cone ratios in the 5°–15° retinal eccentricity range are consistent with histological findings, confirming our ability to resolve the rod mosaic by averaging multiple registered images, without the need for additional image processing. In one subject, we were able to identify the emergence of the first rods at approximately 190 μm from the foveal center, in agreement with previous histological studies. The rod and cone photoreceptor mosaics appear in focus at different retinal depths, with the rod mosaic best focus (i.e., brightest and sharpest) being at least 10 μm shallower than the cones at retinal eccentricities larger than 8°. This study represents an important step in bringing high-resolution imaging to bear on the study of rod disorders. PMID:21750765

Dynamics of Longitudinal Impact in the Variable Cross-Section Rods

NASA Astrophysics Data System (ADS)

Stepanov, R.; Romenskyi, D.; Tsarenko, S.

2018-03-01

Dynamics of longitudinal impact in rods of variable cross-section is considered. Rods of various configurations are used as elements of power pulse systems. There is no single method to the construction of a mathematical model of longitudinal impact on rods. The creation of a general method for constructing a mathematical model of longitudinal impact for rods of variable cross-section is the goal of the article. An elastic rod is considered with a cross-sectional area varying in powers of law from the longitudinal coordinate. The solution of the wave equation is obtained using the Fourier method. Special functions are introduced on the basis of recurrence relations for Bessel functions for solving boundary value problems. The expression for the square of the norm is obtained taking into account the orthogonality property of the eigen functions with weight. For example, the impact of an inelastic mass along the wide end of a conical rod is considered. The expressions for the displacements, forces and stresses of the rod sections are obtained for the cases of sudden velocity communication and the application of force. The proposed mathematical model makes it possible to carry out investigations of the stress-strain state in rods of variable and constant cross-section for various conditions of dynamic effects.

Rapid kinetics of endocytosis at rod photoreceptor synapses depends upon endocytic load and calcium.

PubMed

Cork, Karlene M; Thoreson, Wallace B

2014-05-01

Release from rods is triggered by the opening of L-type Ca2+ channels that lie beneath synaptic ribbons. After exocytosis, vesicles are retrieved by compensatory endocytosis. Previous work showed that endocytosis is dynamin-dependent in rods but dynamin-independent in cones. We hypothesized that fast endocytosis in rods may also differ from cones in its dependence upon the amount of Ca2+ influx and/or endocytic load. We measured exocytosis and endocytosis from membrane capacitance (C m) changes evoked by depolarizing steps in voltage clamped rods from tiger salamander retinal slices. Similar to cones, the time constant for endocytosis in rods was quite fast, averaging <200 ms. We manipulated Ca2+ influx and the amount of vesicle release by altering the duration and voltage of depolarizing steps. Unlike cones, endocytosis kinetics in rods slowed after increasing Ca2+ channel activation with longer step durations or more strongly depolarized voltage steps. Endocytosis kinetics also slowed as Ca2+ buffering was decreased by replacing BAPTA (10 or 1 mM) with the slower Ca2+ buffer EGTA (5 or 0.5 mM) in the pipette solution. These data provide further evidence that endocytosis mechanisms differ in rods and cones and suggest that endocytosis in rods is regulated by both endocytic load and local Ca2+ levels.

Rapid kinetics of endocytosis at rod photoreceptor synapses depends upon endocytic load and calcium

PubMed Central

CORK, KARLENE M.; THORESON, WALLACE B.

2015-01-01

Release from rods is triggered by the opening of L-type Ca2+ channels that lie beneath synaptic ribbons. After exocytosis, vesicles are retrieved by compensatory endocytosis. Previous work showed that endocytosis is dynamin-dependent in rods but dynamin-independent in cones. We hypothesized that fast endocytosis in rods may also differ from cones in its dependence upon the amount of Ca2+ influx and/or endocytic load. We measured exocytosis and endocytosis from membrane capacitance (Cm) changes evoked by depolarizing steps in voltage clamped rods from tiger salamander retinal slices. Similar to cones, the time constant for endocytosis in rods was quite fast, averaging <200 ms. We manipulated Ca2+ influx and the amount of vesicle release by altering the duration and voltage of depolarizing steps. Unlike cones, endocytosis kinetics in rods slowed after increasing Ca2+ channel activation with longer step durations or more strongly depolarized voltage steps. Endocytosis kinetics also slowed as Ca2+ buffering was decreased by replacing BAPTA (10 or 1 mM) with the slower Ca2+ buffer EGTA (5 or 0.5 mM) in the pipette solution. These data provide further evidence that endocytosis mechanisms differ in rods and cones and suggest that endocytosis in rods is regulated by both endocytic load and local Ca2+ levels. PMID:24735554

Maximum striking velocities in strikes with steel rods-the influence of rod length, rod mass and volunteer parameters.

PubMed

Trinh, T X; Heinke, S; Rode, C; Schenkl, S; Hubig, M; Mall, G; Muggenthaler, Holger

2018-03-01

In blunt force trauma to the head caused by attacks with blunt instruments, contact forces can be estimated based on the conservation of momentum if impact velocities are known. The aims of this work were to measure maximum striking velocities and to examine the influence of rod parameters such as rod mass and length as well as volunteer parameters such as sex, age, body height, body mass, body mass index and the average amount of physical exercise. Steel rods with masses of 500, 1000 and 1500 g as well as lengths of 40, 65 and 90 cm were exemplarily tested as blunt instruments. Twenty-nine men and 22 women participated in this study. Each volunteer performed several vertical strikes with the steel rods onto a passive immobile target. Maximum striking velocities were measured by means of a Qualisys motion capture system using high-speed cameras and infrared light. Male volunteers achieved maximum striking velocities between 14.0 and 35.5 m/s whereas female volunteers achieved values between 10.4 and 28.3 m/s. Results show that maximum striking velocities increased with smaller rod masses and less consistently with higher rod lengths. Statistically significant influences were found in the volunteers' sex and average amount of physical exercise.

Evaluation of spinal instrumentation rod bending characteristics for in-situ contouring.

PubMed

Noshchenko, Andriy; Xianfeng, Yao; Armour, Grant Alan; Baldini, Todd; Patel, Vikas V; Ayers, Reed; Burger, Evalina

2011-07-01

Bending characteristics were studied in rods used for spinal instrumentation at in-situ contouring conditions. Five groups of five 6 mm diameter rods made from: cobalt alloy (VITALLIUM), titanium-aluminum-vanadium alloy (SDI™), β-titanium alloy (TNTZ), cold worked stainless steel (STIFF), and annealed stainless steel (MALLEABLE) were studied. The bending procedure was similar to that typically applied for in-situ contouring in the operating room and included two bending cycles: first--bending to 21-24° under load with further release of loading for 10 min, and second--bending to 34-37° at the previously bent site and release of load for 10 min. Applied load, bending stiffness, and springback effect were studied. Statistical evaluation included ANOVA, correlation and regression analysis. TNTZ and SDI™ rods showed the highest (p < 0.05) springback at both bending cycles. VITALLIUM and STIFF rods showed mild springback (p < 0.05). The least (p < 0.05) springback was observed in the MALLEABLE rods. Springback significantly correlated with the bend angle under load (p < 0.001). To reach the necessary bend angle after unloading, over bending should be 37-40% of the required angle in TNTZ and SDI™ rods, 27-30% in VITALLIUM and STIFF rods, and around 20% in MALLEABLE rods. Copyright © 2011 Wiley Periodicals, Inc.

Biophysical mechanism of transient retinal phototropism in rod photoreceptors.

PubMed

Zhao, Xiaohui; Thapa, Damber; Wang, Benquan; Gai, Shaoyan; Yao, Xincheng

2016-02-13

Oblique light stimulation evoked transient retinal phototropism (TRP) has been recently detected in frog and mouse retinas. High resolution microscopy of freshly isolated retinas indicated that the TRP is predominated by rod photoreceptors. Comparative confocal microscopy and optical coherence tomography (OCT) revealed that the TRP predominantly occurred from the photoreceptor outer segment (OS). However, biophysical mechanism of rod OS change is still unknown. In this study, frog retinal slices, which open a cross section of retinal photoreceptor and other functional layers, were used to test the effect of light stimulation on rod OS. Near infrared light microscopy was employed to monitor photoreceptor changes in retinal slices stimulated by a rectangular-shaped visible light flash. Rapid rod OS length change was observed after the stimulation delivery. The magnitude and direction of the rod OS change varied with the position of the rods within the stimulated area. In the center of stimulated region the length of the rod OS shrunk, while in the peripheral region the rod OS tip swung towards center region in the plane perpendicular to the incident stimulus light. Our experimental result and theoretical analysis suggest that the observed TRP may reflect unbalanced disc-shape change due to localized pigment bleaching. Further investigation is required to understand biochemical mechanism of the observed rod OS kinetics. Better study of the TRP may provide a noninvasive biomarker to enable early detection of age-related macular degeneration (AMD) and other diseases that are known to produce retinal photoreceptor dysfunctions.

Optimization of the Hot Forging Processing Parameters for Powder Metallurgy Fe-Cu-C Connecting Rods Based on Finite Element Simulation

NASA Astrophysics Data System (ADS)

Li, Fengxian; Yi, Jianhong; Eckert, Jürgen

2017-12-01

Powder forged connecting rods have the problem of non-uniform density distributions because of their complex geometric shape. The densification behaviors of powder metallurgy (PM) connecting rod preforms during hot forging processes play a significant role in optimizing the connecting rod quality. The deformation behaviors of a connecting rod preform, a Fe-3Cu-0.5C (wt pct) alloy compacted and sintered by the powder metallurgy route (PM Fe-Cu-C), were investigated using the finite element method, while damage and friction behaviors of the material were considered in the complicated forging process. The calculated results agree well with the experimental results. The relationship between the processing parameters of hot forging and the relative density of the connecting rod was revealed. The results showed that the relative density of the hot forged connecting rod at the central shank changed significantly compared with the relative density at the big end and at the small end. Moreover, the relative density of the connecting rod was sensitive to the processing parameters such as the forging velocity and the initial density of the preform. The optimum forging processing parameters were determined and presented by using an orthogonal design method. This work suggests that the processing parameters can be optimized to prepare a connecting rod with uniform density distribution and can help to better meet the requirements of the connecting rod industry.

Homeostatic Plasticity Mediated by Rod-Cone Gap Junction Coupling in Retinal Degenerative Dystrophic RCS Rats

PubMed Central

Hou, Baoke; Fu, Yan; Weng, Chuanhuang; Liu, Weiping; Zhao, Congjian; Yin, Zheng Qin

2017-01-01

Rod-cone gap junctions open at night to allow rod signals to pass to cones and activate the cone-bipolar pathway. This enhances the ability to detect large, dim objects at night. This electrical synaptic switch is governed by the circadian clock and represents a novel form of homeostatic plasticity that regulates retinal excitability according to network activity. We used tracer labeling and ERG recording in the retinae of control and retinal degenerative dystrophic RCS rats. We found that in the control animals, rod-cone gap junction coupling was regulated by the circadian clock via the modulation of the phosphorylation of the melatonin synthetic enzyme arylalkylamine N-acetyltransferase (AANAT). However, in dystrophic RCS rats, AANAT was constitutively phosphorylated, causing rod-cone gap junctions to remain open. A further b/a-wave ratio analysis revealed that dystrophic RCS rats had stronger synaptic strength between photoreceptors and bipolar cells, possibly because rod-cone gap junctions remained open. This was despite the fact that a decrease was observed in the amplitude of both a- and b-waves as a result of the progressive loss of rods during early degenerative stages. These results suggest that electric synaptic strength is increased during the day to allow cone signals to pass to the remaining rods and to be propagated to rod bipolar cells, thereby partially compensating for the weak visual input caused by the loss of rods. PMID:28473754

Biophysical mechanism of transient retinal phototropism in rod photoreceptors

NASA Astrophysics Data System (ADS)

Zhao, Xiaohui; Thapa, Damber; Wang, Benquan; Gai, Shaoyan; Yao, Xincheng

2016-03-01

Oblique light stimulation evoked transient retinal phototropism (TRP) has been recently detected in frog and mouse retinas. High resolution microscopy of freshly isolated retinas indicated that the TRP is predominated by rod photoreceptors. Comparative confocal microscopy and optical coherence tomography (OCT) revealed that the TRP predominantly occurred from the photoreceptor outer segment (OS). However, biophysical mechanism of rod OS change is still unknown. In this study, frog retinal slices, which open a cross section of retinal photoreceptor and other functional layers, were used to test the effect of light stimulation on rod OS. Near infrared light microscopy was employed to monitor photoreceptor changes in retinal slices stimulated by a rectangular-shaped visible light flash. Rapid rod OS length change was observed after the stimulation delivery. The magnitude and direction of the rod OS change varied with the position of the rods within the stimulated area. In the center of stimulated region the length of the rod OS shrunk, while in the peripheral region the rod OS tip swung towards center region in the plane perpendicular to the incident stimulus light. Our experimental result and theoretical analysis suggest that the observed TRP may reflect unbalanced disc-shape change due to localized pigment bleaching. Further investigation is required to understand biochemical mechanism of the observed rod OS kinetics. Better study of the TRP may provide a noninvasive biomarker to enable early detection of age-related macular degeneration (AMD) and other diseases that are known to produce retinal photoreceptor dysfunctions.

Comparative Study Between Cobalt Chrome and Titanium Alloy Rods for Multilevel Spinal Fusion: Proximal Junctional Kyphosis More Frequently Occurred in Patients Having Cobalt Chrome Rods.

PubMed

Han, Sanghyun; Hyun, Seung-Jae; Kim, Ki-Jeong; Jahng, Tae-Ahn; Kim, Hyun-Jib

2017-07-01

The use of titanium alloy (Ti) rods is frequently associated with rod fracture after spinal fixation. To address this issue, cobalt chrome (CoCr) rods, which are advantageous because of their greater strength and resistance to fatigue relative to Ti rods, have been introduced. The purpose of the present study was to compare radiographic outcomes after the use of Ti versus CoCr rods in a matched cohort of patients undergoing posterior spinal fusion for treatment of spinal instability. We retrospectively reviewed data from patients who had undergone spinal fusion involving more than 3 levels at a single institution between 2004 and 2015. Patients were matched for age, diagnosis, 3-column osteotomy, levels fused, and T score. Fifty patients with Ti rods were identified and appropriately matched to 50 consecutive patients with CoCr rods. The distributions of age at surgery, sex, diagnosis, 3-column osteotomy, levels fused, number of patients with previous surgical procedures, and T score did not significantly differ between the 2 groups. However, there were significant differences in length of follow-up (CoCr, 25.0 vs. Ti, 28.5 months; P < 0.001), fusion rate (CoCr, 45 [90%] vs. Ti, 33 [66%]; P = 0.004), occurrence of rod breakage (CoCr, 0 vs. T, 8 [16%]; P = 0.006), and junctional kyphosis (CoCr, 24 [46%] vs. Ti, 9 [18%]; P = 0.003). Our findings indicate that the use of CoCr rods is effective in ensuring stability of the posterior spinal construct and accomplishment of spinal fusion. Furthermore, our results indicate that junctional kyphosis may occur more frequently in CoCr systems than in Ti systems. Copyright © 2017 Elsevier Inc. All rights reserved.

Dependence of N-polar GaN rod morphology on growth parameters during selective area growth by MOVPE

NASA Astrophysics Data System (ADS)

Li, Shunfeng; Wang, Xue; Mohajerani, Matin Sadat; Fündling, Sönke; Erenburg, Milena; Wei, Jiandong; Wehmann, Hergo-Heinrich; Waag, Andreas; Mandl, Martin; Bergbauer, Werner; Strassburg, Martin

2013-02-01

Selective area growth of GaN rods by metalorganic vapor phase epitaxy has attracted great interest due to its novel applications in optoelectronic and photonics. In this work, we will present the dependence of GaN rod morphology on various growth parameters i.e. growth temperature, H2/N2 carrier gas concentration, V/III ratio, total carrier gas flow and reactor pressure. It is found that higher growth temperature helps to increase the aspect ratio of the rods, but reduces the height homogeneity. Furthermore, H2/N2 carrier gas concentration is found to be a critical factor to obtain vertical rod growth. Pure nitrogen carrier gas leads to irregular growth of GaN structure, while an increase of hydrogen carrier gas results in vertical GaN rod growth. Higher hydrogen carrier gas concentration also reduces the diameter and enhances the aspect of the GaN rods. Besides, increase of V/III ratio causes reduction of the aspect ratio of N-polar GaN rods, which could be explained by the relatively lower growth rate on (000-1) N-polar top surface when supplying more ammonia. In addition, an increase of the total carrier gas flow leads to a decrease in the diameter and the average volume of GaN rods. These phenomena are tentatively explained by the change of partial pressure of the source materials and boundary layer thickness in the reactor. Finally, it is shown that the average volume of the N-polar GaN rods keeps a similar value for a reactor pressure PR of 66 and 125 mbar, while an incomplete filling of the pattern opening is observed with PR of 250 mbar. Room temperature photoluminescence spectrum of the rods is also briefly discussed.

Growth Speed and Substitution Effects on Alignment and Thermal Transport Properties of Bi-2212 Textured Superconductors

NASA Astrophysics Data System (ADS)

Ozabaci, M.; Rasekh, Sh.; Kizilaslan, O.; Madre, M. A.; Sotelo, A.; Yakinci, M. E.

2015-01-01

Fe-substituted superconducting thin BiSrCaCuO rods with nominal compositions of Bi2Sr2Ca1Cu2- x Fe x O8+ δ ( x = 0, 0.01, 0.03, 0.05, and 0.1) were fabricated using the laser floating zone technique at two different growth speeds, 15 mm h-1 and 30 mm h-1. The influences of growth speed and Fe substitution on the grain alignment in the rods were evaluated by means of x-ray pole figure studies. The obtained results showed that both applied growth speed and Fe substitution play a crucial role on grain alignment, which is strongly connected with the current-carrying capacity of the rods. It was found that the rods grown at 15 mm h-1 (G15) have stronger orientation than the rods grown at 30 mm h-1 (G30). However, in contrast to the G15 rods, an increased substitution rate improved the orientation of the G30 rods. Another important observation is that the increase on the substitution caused a decrease on the grain size of all the rods. The decrease of critical temperature values of the rods upon substitution was ascribed to both grain size effect and formation of a nonsuperconducting Fe-rich phase detected in scanning electron microscope/energy-dispersive x-ray analyses. The thermal conductivity values of the G15 and G30 rods were found to be in the range of 0.9-1.9 and 1.1-1.18 W m-1 K-1 at 150 K, respectively. The higher values of figure of merit ( ZT), at all temperature ranges, were obtained from the highest substituted rods ( x = 0.1) for both of the applied growth speeds. In addition, it was observed that the ZT of G30 rods are up to three times higher than that of G15 ones.

Autofusion in the immature spine treated with growing rods.

PubMed

Cahill, Patrick J; Marvil, Sean; Cuddihy, Laury; Schutt, Corey; Idema, Jocelyn; Clements, David H; Antonacci, M Darryl; Asghar, Jahangir; Samdani, Amer F; Betz, Randal R

2010-10-15

Retrospective case review of skeletally immature patients treated with growing rods. Patients received an average of 9.6 years follow-up care. (1) to identify the rate of autofusion in the growing spine with the use of growing rods; (2) to quantify how much correction can be attained with definitive instrumented fusion after long-term treatment with growing rods; and (3) to describe the extent of Smith-Petersen osteotomies required to gain correction of an autofused spine following growing rod treatment. The safety and use of growing rods for curve correction and maintenance in the growing spine population has been established in published reports. While autofusion has been reported, the prevalence and sequelae are not known. Nine skeletally immature children with scoliosis were identified who had been treated using growing rods. A retrospective review of the medical records and radiographs was conducted and the following data collected: complications, pre- and postoperative Cobb angles at time of initial surgery (growing rod placement), pre- and postoperative Cobb angles at time of final surgery (growing rod removal and definitive fusion), total spine length as measured from T1-S1, % correction since initiation of treatment and at definitive fusion, total number of surgeries, and number of patients found to have autofusion at the time of device removal. The rate of autofusion in children treated with growing rods was 89%. The average percent of the Cobb angle correction obtained at definitive fusion was 44%. On average, 7 osteotomies per patient were required at the time of definitive fusion due to autofusion. Although growing rods have efficacy in the control of deformity within the growing spine, they also have adverse effects on the spine. Immature spines treated with a growing rod have high rates of unintended autofusion which can possibly lead to difficult and only moderate correction at the time of definitive fusion.

Phosphorylation-independent suppression of light-activated visual pigment by arrestin in carp rods and cones.

PubMed

Tomizuka, Junko; Tachibanaki, Shuji; Kawamura, Satoru

2015-04-10

Visual pigment in photoreceptors is activated by light. Activated visual pigment (R*) is believed to be inactivated by phosphorylation of R* with subsequent binding of arrestin. There are two types of photoreceptors, rods and cones, in the vertebrate retina, and they express different subtypes of arrestin, rod and cone type. To understand the difference in the function between rod- and cone-type arrestin, we first identified the subtype of arrestins expressed in rods and cones in carp retina. We found that two rod-type arrestins, rArr1 and rArr2, are co-expressed in a rod and that a cone-type arrestin, cArr1, is expressed in blue- and UV-sensitive cones; the other cone-type arrestin, cArr2, is expressed in red- and green-sensitive cones. We quantified each arrestin subtype and estimated its concentration in the outer segment of a rod or a cone in the dark; they were ∼0.25 mm (rArr1 plus rArr2) in a rod and 0.6-0.8 mm (cArr1 or cArr2) in a cone. The effect of each arrestin was examined. In contrast to previous studies, both rod and cone arrestins suppressed the activation of transducin in the absence of visual pigment phosphorylation, and all of the arrestins examined (rArr1, rArr2, and cArr2) bound transiently to most probably nonphosphorylated R*. One rod arrestin, rArr2, bound firmly to phosphorylated pigment, and the other two, rArr1 and cArr2, once bound to phosphorylated R* but dissociated from it during incubation. Our results suggested a novel mechanism of arrestin effect on the suppression of the R* activity in both rods and cones. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

Characterizing the original ejection velocity field of the Koronis family

NASA Astrophysics Data System (ADS)

Carruba, V.; Nesvorný, D.; Aljbaae, S.

2016-06-01

An asteroid family forms as a result of a collision between an impactor and a parent body. The fragments with ejection speeds higher than the escape velocity from the parent body can escape its gravitational pull. The cloud of escaping debris can be identified by the proximity of orbits in proper element, or frequency, domains. Obtaining estimates of the original ejection speed can provide valuable constraints on the physical processes occurring during collision, and used to calibrate impact simulations. Unfortunately, proper elements of asteroids families are modified by gravitational and non-gravitational effects, such as resonant dynamics, encounters with massive bodies, and the Yarkovsky effect, such that information on the original ejection speeds is often lost, especially for older, more evolved families. It has been recently suggested that the distribution in proper inclination of the Koronis family may have not been significantly perturbed by local dynamics, and that information on the component of the ejection velocity that is perpendicular to the orbital plane (vW), may still be available, at least in part. In this work we estimate the magnitude of the original ejection velocity speeds of Koronis members using the observed distribution in proper eccentricity and inclination, and accounting for the spread caused by dynamical effects. Our results show that (i) the spread in the original ejection speeds is, to within a 15% error, inversely proportional to the fragment size, and (ii) the minimum ejection velocity is of the order of 50 m/s, with larger values possible depending on the orbital configuration at the break-up.

Rod electrical coupling is controlled by a circadian clock and dopamine in mouse retina

PubMed Central

Jin, Nan Ge; Chuang, Alice Z; Masson, Philippe J; Ribelayga, Christophe P

2015-01-01

Key points Rod photoreceptors play a key role in vision in dim light; in the mammalian retina, although rods are anatomically connected or coupled by gap junctions, a type of electrical synapse, the functional importance and regulation of rod coupling has remained elusive. We have developed a new technique in the mouse: perforated patch-clamp recording of rod inner segments in isolated intact retinae maintained by superfusion. We find that rod electrical coupling is controlled by a circadian clock and dopamine, and is weak during the day and stronger at night. The results also indicate that the signal-to-noise ratio for a dim light response is increased at night because of coupling. Our observations will provide a framework for understanding the daily variations in human vision as well as the basis of specific retinal malfunctions. Abstract Rod single-photon responses are critical for vision in dim light. Electrical coupling via gap junction channels shapes the light response properties of vertebrate photoreceptors, but the regulation of rod coupling and its impact on the single-photon response have remained unclear. To directly address these questions, we developed a perforated patch-clamp recording technique and recorded from single rod inner segments in isolated intact neural mouse retinae, maintained by superfusion. Experiments were conducted at different times of the day or under constant environmental conditions, at different times across the circadian cycle. We show that rod electrical coupling is regulated by a circadian clock and dopamine, so that coupling is weak during the day and strong at night. Altogether, patch-clamp recordings of single-photon responses in mouse rods, tracer coupling, receptive field measurements and pharmacological manipulations of gap junction and dopamine receptor activity provide compelling evidence that rod coupling is modulated in a circadian manner. These data are consistent with computer modelling. At night, single-photon responses are smaller due to coupling, but the signal-to-noise ratio for a dim (multiphoton) light response is increased at night because of signal averaging between coupled rods. PMID:25616058

In vitro degradation, flexural, compressive and shear properties of fully bioresorbable composite rods.

PubMed

Felfel, R M; Ahmed, I; Parsons, A J; Walker, G S; Rudd, C D

2011-10-01

Several studies have investigated self-reinforced polylactic acid (SR-PLA) and polyglycolic acid (SR-PGA) rods which could be used as intramedullary (IM) fixation devices to align and stabilise bone fractures. This study investigated totally bioresorbable composite rods manufactured via compression moulding at ~100 °C using phosphate glass fibres (of composition 50P(2)O(5)-40CaO-5Na(2)O-5Fe(2)O(3) in mol%) to reinforce PLA with an approximate fibre volume fraction (v(f)) of 30%. Different fibre architectures (random and unidirectional) were investigated and pure PLA rods were used as control samples. The degradation profiles and retention of mechanical properties were investigated and PBS was selected as the degradation medium. Unidirectional (P50 UD) composite rods had 50% higher initial flexural strength as compared to PLA and 60% higher in comparison to the random mat (P50 RM) composite rods. Similar initial profiles for flexural modulus were also seen comparing the P50 UD and P50 RM rods. Higher shear strength properties were seen for P50 UD in comparison to P50 RM and PLA rods. However, shear stiffness values decreased rapidly (after a week) whereas the PLA remained approximately constant. For the compressive strength studies, P50 RM and PLA rods remained approximately constant, whilst for the P50 UD rods a significantly higher initial value was obtained, which decreased rapidly after 3 days immersion in PBS. However, the mechanical properties decreased after immersion in PBS as a result of the plasticisation effect of water within the composite and degradation of the fibres. The fibres within the random and unidirectional composite rods (P50 RM and P50 UD) degraded leaving behind microtubes as seen from the SEM micrographs (after 28 days degradation) which in turn created a porous structure within the rods. This was the main reason attributed for the increase seen in mass loss and water uptake for the composite rods (~17% and ~16%, respectively). Copyright © 2011 Elsevier Ltd. All rights reserved.

Synthesis of Zinc Oxide Nanorods via the Formation of Sea Urchin Structures and Their Photoluminescence after Heat Treatment.

PubMed

Karlsson, Mattias E; Mamie, Yann C; Calamida, Andrea; Gardner, James M; Ström, Valter; Pourrahimi, Amir Masoud; Olsson, Richard T

2018-05-01

A protocol for the aqueous synthesis of ca. 1-μm-long zinc oxide (ZnO) nanorods and their growth at intermediate reaction progression is presented, together with photoluminescence (PL) characteristics after heat treatment at temperatures of up to 1000 °C. The existence of solitary rods after the complete reaction (60 min) was traced back to the development of sea urchin structures during the first 5 s of the precipitation. The rods primarily formed in later stages during the reaction due to fracture, which was supported by the frequently observed broken rod ends with sharp edges in the final material, in addition to tapered uniform rod ends consistent with their natural growth direction. The more dominant rod growth in the c direction (extending the length of the rods), together with the appearance of faceted surfaces on the sides of the rods, occurred at longer reaction times (>5 min) and generated zinc-terminated particles that were more resistant to alkaline dissolution. A heat treatment for 1 h at 600 or 800 °C resulted in a smoothing of the rod surfaces, and PL measurements displayed a decreased defect emission at ca. 600 nm, which was related to the disappearance of lattice imperfections formed during the synthesis. A heat treatment at 1000 °C resulted in significant crystal growth reflected as an increase in luminescence at shorter wavelengths (ca. 510 nm). Electron microscopy revealed that the faceted rod structure was lost for ZnO rods exposed to temperatures above 600 °C, whereas even higher temperatures resulted in particle sintering and/or mass redistribution along the initially long and slender ZnO rods. The synthesized ZnO rods were a more stable Wurtzite crystal structure than previously reported ball-shaped ZnO consisting of merging sheets, which was supported by the shifts in PL spectra occurring at ca. 200 °C higher annealing temperature, in combination with a smaller thermogravimetric mass loss occurring upon heating the rods to 800 °C.

Retrieval and clinical analysis of distraction-based dual growing rod constructs for early-onset scoliosis.

PubMed

Hill, Genevieve; Nagaraja, Srinidhi; Akbarnia, Behrooz A; Pawelek, Jeff; Sponseller, Paul; Sturm, Peter; Emans, John; Bonangelino, Pablo; Cockrum, Joshua; Kane, William; Dreher, Maureen

2017-10-01

Growing rod constructs are an important contribution for treating patients with early-onset scoliosis. These devices experience high failure rates, including rod fractures. The objective of this study was to identify the failure mechanism of retrieved growing rods, and to identify differences between patients with failed and intact constructs. Growing rod patients who had implant removal and were previously enrolled in a multicenter registry were eligible for this study. Forty dual-rod constructs were retrieved from 36 patients across four centers, and 34 of those constructs met the inclusion criteria. Eighteen constructs failed due to rod fracture. Sixteen intact constructs were removed due to final fusion (n=7), implant exchange (n=5), infection (n=2), or implant prominence (n=2). Analyses of clinical registry data, radiographs, and retrievals were the outcome measures. Retrievals were analyzed with microscopic imaging (optical and scanning electron microscopy) for areas of mechanical failure, damage, and corrosion. Failure analyses were conducted on the fracture surfaces to identify failure mechanism(s). Statistical analyses were performed to determine significant differences between the failed and intact groups. The failed rods fractured due to bending fatigue under flexion motion. Construct configuration and loading dictate high bending stresses at three distinct locations along the construct: (1) mid-construct, (2) adjacent to the tandem connector, or (3) adjacent to the distal anchor foundation. In addition, high torques used to insert set screws may create an initiation point for fatigue. Syndromic scoliosis, prior rod fractures, increase in patient weight, and rigid constructs consisting of tandem connectors and multiple crosslinks were associated with failure. This is the first study to examine retrieved, failed growing rod implants across multiple centers. Our analysis found that rod fractures are due to bending fatigue, and that stress concentrations play an important role in rod fractures. Recommendations are made on surgical techniques, such as the use of torque-limiting wrenches or not exceeding the prescribed torques. Additional recommendations include frequent rod replacement in select patients during scheduled surgeries. Published by Elsevier Inc.

Activity associated with coronal mass ejections at solar minimum - SMM observations from 1984-1986

NASA Technical Reports Server (NTRS)

St. Cyr, O. C.; Webb, D. F.

1991-01-01

Seventy-three coronal mass ejections (CMEs) observed by the coronagraph aboard SMM between 1984 and 1986 were examined in order to determine the distribution of various forms of solar activity that were spatially and temporally associated with mass ejections during solar minimum phase. For each coronal mass ejection a speed was measured, and the departure time of the transient from the lower corona estimated. Other forms of solar activity that appeared within 45 deg longitude and 30 deg latitude of the mass ejection and within +/-90 min of its extrapolated departure time were explored. The statistical results of the analysis of these 73 CMEs are presented, and it is found that slightly less than half of them were infrequently associated with other forms of solar activity. It is suggested that the distribution of the various forms of activity related to CMEs does not change at different phases of the solar cycle. For those CMEs with associations, it is found that eruptive prominences and soft X-rays were the most likely forms of activity to accompany the appearance of mass ejections.

Coronal Mass Ejections in September 2017 from Monitoring of Interplanetary Scintillations with the Large Phased Array of the Lebedev Institute of Physics

NASA Astrophysics Data System (ADS)

Chashei, I. V.; Tyul'bashev, S. A.; Shishov, V. I.; Subaev, I. A.

2018-05-01

Results of monitoring of interplanetary scintillations with the Large Phased Array of the Pushchino Radio AstronomyObservatory at 111 MHz during a period of flare activity of the Sun in the first ten days of September 2017 are presented. Enhancements of scintillations associated with interplanetary coronal mass ejections propagating after limb flares have been recorded. The propagation velocities are estimated to be about 2000 km/s for an ejection on September 7 and about 1000 km/s for an ejection on September 6. It is shown that, during the propagation from the Sun, the lateral part of the ejections decelerates faster than its leading part. Night-time enhancements of second-timescale scintillations during periods of high geomagnetic activity have an ionospheric origin.

Hydraulic Actuator for Ganged Control Rods

NASA Technical Reports Server (NTRS)

Thompson, D. C.; Robey, R. M.

1986-01-01

Hydraulic actuator moves several nuclear-reactor control rods in unison. Electromagnetic pump pushes liquid lithium against ends of control rods, forcing them out of or into nuclear reactor. Color arrows show lithium flow for reactor startup and operation. Flow reversed for shutdown. Conceived for use aboard spacecraft, actuator principle applied to terrestrial hydraulic machinery involving motion of ganged rods.

49 CFR 230.96 - Main, side, and valve motion rods.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 49 Transportation 4 2010-10-01 2010-10-01 false Main, side, and valve motion rods. 230.96 Section... Locomotives and Tenders Driving Gear § 230.96 Main, side, and valve motion rods. (a) General. Main, side or... immediately and repaired or renewed. (b) Repairs. Repairs, and welding of main, side or valve motion rods...

49 CFR 230.96 - Main, side, and valve motion rods.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 49 Transportation 4 2011-10-01 2011-10-01 false Main, side, and valve motion rods. 230.96 Section... Locomotives and Tenders Driving Gear § 230.96 Main, side, and valve motion rods. (a) General. Main, side or... immediately and repaired or renewed. (b) Repairs. Repairs, and welding of main, side or valve motion rods...

49 CFR 230.96 - Main, side, and valve motion rods.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 49 Transportation 4 2013-10-01 2013-10-01 false Main, side, and valve motion rods. 230.96 Section... Locomotives and Tenders Driving Gear § 230.96 Main, side, and valve motion rods. (a) General. Main, side or... immediately and repaired or renewed. (b) Repairs. Repairs, and welding of main, side or valve motion rods...

49 CFR 230.96 - Main, side, and valve motion rods.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 49 Transportation 4 2014-10-01 2014-10-01 false Main, side, and valve motion rods. 230.96 Section... Locomotives and Tenders Driving Gear § 230.96 Main, side, and valve motion rods. (a) General. Main, side or... immediately and repaired or renewed. (b) Repairs. Repairs, and welding of main, side or valve motion rods...

49 CFR 230.96 - Main, side, and valve motion rods.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 49 Transportation 4 2012-10-01 2012-10-01 false Main, side, and valve motion rods. 230.96 Section... Locomotives and Tenders Driving Gear § 230.96 Main, side, and valve motion rods. (a) General. Main, side or... immediately and repaired or renewed. (b) Repairs. Repairs, and welding of main, side or valve motion rods...

Inverted Control Rod Lock-In Device

DOEpatents

Brussalis, W. G.; Bost, G. E.

1962-12-01

A mechanism which prevents control rods from dropping out of the reactor core in the event the vessel in which the reactor is mounted should capsize is described. The mechanism includes a pivoted toothed armature which engages the threaded control rod lead screw and prevents removal of the rod whenever the armature is not attracted by the provided electromagnetic means. (AEC)

78 FR 28190 - Carbon and Certain Alloy Steel Wire Rod From Mexico: Final Results of Antidumping Duty...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-05-14

... Steel Wire Rod From Mexico: Final Results of Antidumping Duty Administrative Review; 2010-2011 AGENCY... results of the administrative review of the antidumping duty order on carbon and certain alloy steel wire rod (wire rod) from Mexico. The period of review (POR) is October 1, 2010, through September 30, 2011...

77 FR 66954 - Carbon and Certain Alloy Steel Wire Rod From Mexico: Preliminary Results of Antidumping Duty...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-11-08

... Steel Wire Rod From Mexico: Preliminary Results of Antidumping Duty Administrative Review; 2010-2011... conducting an administrative review of the antidumping duty order on carbon and certain alloy steel wire rod (wire rod) from Mexico. The period of review is October 1, 2010, through September 30, 2011, and the...

78 FR 60316 - Carbon and Certain Alloy Steel Wire Rod From Brazil, Indonesia, Mexico, Moldova, Trinidad and...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-10-01

... (Second Review)] Carbon and Certain Alloy Steel Wire Rod From Brazil, Indonesia, Mexico, Moldova, Trinidad... certain alloy steel wire rod from Brazil and antidumping duty orders on carbon and certain alloy steel... reviews of the antidumping duty order on carbon and certain alloy steel wire rod from Mexico. The...

78 FR 76653 - Carbon and Certain Alloy Steel Wire Rod From Brazil, Indonesia, Mexico, Moldova, Trinidad and...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-12-18

... 962 (Second Review)] Carbon and Certain Alloy Steel Wire Rod From Brazil, Indonesia, Mexico, Moldova... orders on carbon and certain alloy steel wire rod from Brazil, Indonesia, Mexico, Moldova, Trinidad and... carbon and certain alloy steel wire rod from Brazil, Indonesia, Mexico, Moldova, Trinidad and Tobago, and...

Decay Times and Quality Factors for a Resonance Apparatus

ERIC Educational Resources Information Center

Stephens, Heather; Tam, Austin; Moloney, Michael

2011-01-01

The commercial resonance demonstration apparatus shown in Fig. 1 exhibits curious behavior. It consists of three pairs of slender spring-steel rods attached to a horizontal bar. When one of the rods is pulled aside and released, the rod of corresponding length is excited into visible motion, but the other rods remain apparently stationary. This…

76 FR 74012 - Airworthiness Directives; the Boeing Company Airplanes

Federal Register 2010, 2011, 2012, 2013, 2014

2011-11-30

... new structural members and new tie rod(s) and attach fittings on the left and right sides of the... members and new tie rod(s) and attach fittings on the left and right sides of the lowered ceiling support...). SUMMARY: We propose to adopt a new airworthiness directive (AD) for certain Boeing Company Model 777-200...

Temperature actuated automatic safety rod release

DOEpatents

Hutter, E.; Pardini, J.A.; Walker, D.E.

1984-03-13

A temperature-actuated apparatus is disclosed for releasably supporting a safety rod in a nuclear reactor, comprising a safety rod upper adapter having a retention means, a drive shaft which houses the upper adapter, and a bimetallic means supported within the drive shaft and having at least one ledge which engages a retention means of the safety rod upper adapter. A pre-determined increase in temperature causes the bimetallic means to deform so that the ledge disengages from the retention means, whereby the bimetallic means releases the safety rod into the core of the reactor.

Temperature actuated automatic safety rod release

DOEpatents

Hutter, Ernest; Pardini, John A.; Walker, David E.

1987-01-01

A temperature-actuated apparatus is disclosed for releasably supporting a safety rod in a nuclear reactor, comprising a safety rod upper adapter having a retention means, a drive shaft which houses the upper adapter, and a bimetallic means supported within the drive shaft and having at least one ledge which engages a retention means of the safety rod upper adapter. A pre-determined increase in temperature causes the bimetallic means to deform so that the ledge disengages from the retention means, whereby the bimetallic means releases the safety rod into the core of the reactor.

Pultruded Rod/Overwrap Testing for Various Stitched Stringer Configurations

NASA Technical Reports Server (NTRS)

Leone, Frank A., Jr.

2016-01-01

The unidirectional carbon pultruded rod running through the tops of the stringers is a key design feature of the Pultruded Rod Efficient Unitized Structure (PRSEUS) concept as applied to aircraft fuselage structure. Reported herein are the test methods and results from a test campaign in which the strength of the rod/overwrap interface of various PRSEUS stringer configurations were characterized. The different stringer configurations included different materials and stacking sequences for the stringer overwrap and whether or not an additional layer of adhesive was included between the rod and the overwrap.

Rod-Coil Block Polyimide Copolymers

NASA Technical Reports Server (NTRS)

Meador, Mary Ann B. (Inventor); Kinder, James D. (Inventor)

2005-01-01

This invention is a series of rod-coil block polyimide copolymers that are easy to fabricate into mechanically resilient films with acceptable ionic or protonic conductivity at a variety of temperatures. The copolymers consist of short-rigid polyimide rod segments alternating with polyether coil segments. The rods and coil segments can be linear, branched or mixtures of linear and branched segments. The highly incompatible rods and coil segments phase separate, providing nanoscale channels for ion conduction. The polyimide segments provide dimensional and mechanical stability and can be functionalized in a number of ways to provide specialized functions for a given application. These rod-coil black polyimide copolymers are particularly useful in the preparation of ion conductive membranes for use in the manufacture of fuel cells and lithium based polymer batteries.

Structure and Growth of Rod-Shaped Mn Ultrafine Particle

NASA Astrophysics Data System (ADS)

Kido, Osamu; Suzuki, Hitoshi; Saito, Yoshio; Kaito, Chihiro

2003-09-01

The structure of rod-shaped Mn ultrafine particles was elucidated by electron microscopy. Mn ultrafine particles have characteristic tristetrahedron (α-Mn), rhombic dodecahedron (β-Mn) and rod-shape crystal habits. It was found that the rod-shaped particle resulted from the parallel coalescence of β-Mn particles with the size of 50 nm. Detailed analysis of the defects seen in large rod-shaped particles with the width of 100 nm indicated a mixture of α- and β-phases. A size effect on the phase transition from β to α was observed throughout the rod-shaped crystal structure. The structure and growth of Mn particles were discussed based on the outline of the smoke and the temperature distribution in the smoke.

Nuclear reactor control apparatus

DOEpatents

Sridhar, Bettadapur N.

1983-10-25

Nuclear reactor safety rod release apparatus comprises a ring which carries detents normally positioned in an annular recess in outer side of the rod, the ring being held against the lower end of a drive shaft by magnetic force exerted by a solenoid carried by the drive shaft. When the solenoid is de-energized, the detent-carrying ring drops until the detents contact a cam surface associated with the lower end of the drive shaft, at which point the detents are cammed out of the recess in the safety rod to release the rod from the drive shaft. In preferred embodiments of the invention, an additional latch is provided to release a lower portion of a safety rod under conditions that may interfere with movement of the entire rod.

The Case for Using Blunt-Tipped Lightning Rods as Strike Receptors.

NASA Astrophysics Data System (ADS)

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

2003-07-01

Conventional lightning rods used in the United States have sharp tips, a practice derived from Benjamin Franklin's discovery of a means to obtain protection from lightning. However, the virtue of sharp tips for strike reception has never been established. An examination of the relevant physics shows that very strong electric fields are required above the tips of rods in order that they function as strike receptors but that the gradients of the field strength over sharp-tipped rods are so great that, at distances of a few millimeters, the local fields are often too weak for the development of upward-going streamers. In field tests, rods with rounded tips have been found to be better strike receptors than were nearby sharp-tipped rods.

Right Ventricular Ejection Fraction Is Incremental to Left Ventricular Ejection Fraction for the Prediction of Future Arrhythmic Events in Patients With Systolic Dysfunction.

PubMed

Mikami, Yoko; Jolly, Umjeet; Heydari, Bobak; Peng, Mingkai; Almehmadi, Fahad; Zahrani, Mohammed; Bokhari, Mahmoud; Stirrat, John; Lydell, Carmen P; Howarth, Andrew G; Yee, Raymond; White, James A

2017-01-01

Left ventricular ejection fraction remains the primary risk stratification tool used in the selection of patients for implantable cardioverter defibrillator therapy. However, this solitary marker fails to identify a substantial portion of patients experiencing sudden cardiac arrest. In this study, we examined the incremental value of considering right ventricular ejection fraction for the prediction of future arrhythmic events in patients with systolic dysfunction using the gold standard of cardiovascular magnetic resonance. Three hundred fourteen consecutive patients with ischemic cardiomyopathy or nonischemic dilated cardiomyopathy undergoing cardiovascular magnetic resonance were followed for the primary outcome of sudden cardiac arrest or appropriate implantable cardioverter defibrillator therapy. Blinded quantification of left ventricular and right ventricular (RV) volumes was performed from standard cine imaging. Quantification of fibrosis from late gadolinium enhancement imaging was incrementally performed. RV dysfunction was defined as right ventricular ejection fraction ≤45%. Among all patients (164 ischemic cardiomyopathy, 150 nonischemic dilated cardiomyopathy), the mean left ventricular ejection fraction was 32±12% (range, 6-54%) with mean right ventricular ejection fraction of 48±15% (range, 7-78%). At a median of 773 days, 49 patients (15.6%) experienced the primary outcome (9 sudden cardiac arrest, 40 appropriate implantable cardioverter defibrillator therapies). RV dysfunction was independently predictive of the primary outcome (hazard ratio=2.98; P=0.002). Among those with a left ventricular ejection fraction >35% (N=121; mean left ventricular ejection fraction, 45±6%), RV dysfunction provided an adjusted hazard ratio of 4.2 (P=0.02). RV dysfunction is a strong, independent predictor of arrhythmic events. Among patients with mild to moderate LV dysfunction, a cohort greatly contributing to global sudden cardiac arrest burden, this marker provides robust discrimination of high- versus low-risk subjects. © 2017 American Heart Association, Inc.

Verification of Space Weather Forecasts using Terrestrial Weather Approaches

NASA Astrophysics Data System (ADS)

Henley, E.; Murray, S.; Pope, E.; Stephenson, D.; Sharpe, M.; Bingham, S.; Jackson, D.

2015-12-01

The Met Office Space Weather Operations Centre (MOSWOC) provides a range of 24/7 operational space weather forecasts, alerts, and warnings, which provide valuable information on space weather that can degrade electricity grids, radio communications, and satellite electronics. Forecasts issued include arrival times of coronal mass ejections (CMEs), and probabilistic forecasts for flares, geomagnetic storm indices, and energetic particle fluxes and fluences. These forecasts are produced twice daily using a combination of output from models such as Enlil, near-real-time observations, and forecaster experience. Verification of forecasts is crucial for users, researchers, and forecasters to understand the strengths and limitations of forecasters, and to assess forecaster added value. To this end, the Met Office (in collaboration with Exeter University) has been adapting verification techniques from terrestrial weather, and has been working closely with the International Space Environment Service (ISES) to standardise verification procedures. We will present the results of part of this work, analysing forecast and observed CME arrival times, assessing skill using 2x2 contingency tables. These MOSWOC forecasts can be objectively compared to those produced by the NASA Community Coordinated Modelling Center - a useful benchmark. This approach cannot be taken for the other forecasts, as they are probabilistic and categorical (e.g., geomagnetic storm forecasts give probabilities of exceeding levels from minor to extreme). We will present appropriate verification techniques being developed to address these forecasts, such as rank probability skill score, and comparing forecasts against climatology and persistence benchmarks. As part of this, we will outline the use of discrete time Markov chains to assess and improve the performance of our geomagnetic storm forecasts. We will also discuss work to adapt a terrestrial verification visualisation system to space weather, to help MOSWOC forecasters view verification results in near real-time; plans to objectively assess flare forecasts under the EU Horizon 2020 FLARECAST project; and summarise ISES efforts to achieve consensus on verification.

Improved Measurement of Ejection Velocities From Craters Formed in Sand

NASA Technical Reports Server (NTRS)

Cintala, Mark J.; Byers, Terry; Cardenas, Francisco; Montes, Roland; Potter, Elliot E.

2014-01-01

A typical impact crater is formed by two major processes: compression of the target (essentially equivalent to a footprint in soil) and ejection of material. The Ejection-Velocity Measurement System (EVMS) in the Experimental Impact Laboratory has been used to study ejection velocities from impact craters formed in sand since the late 1990s. The original system used an early-generation Charge-Coupled Device (CCD) camera; custom-written software; and a complex, multicomponent optical system to direct laser light for illumination. Unfortunately, the electronic equipment was overtaken by age, and the software became obsolete in light of improved computer hardware.

Modeling of meteoroid streams: The velocity of ejection of meteoroids from comets (a review)

NASA Astrophysics Data System (ADS)

Ryabova, G. O.

2013-05-01

An analytical review of the models of ejection of meteoroids from cometary nuclei is presented. Different formulas for the ejection velocity of meteoroids and the corresponding parameters are discussed and compared with the use of comet Halley and the Geminids meteoroid stream as examples. The ejection velocities obtained from observations of the dust trails of comets are discussed, and the values for comets 2P/Encke, 4P/Faye, 17P/Holmes, 22P/Kopff, and 67P/Churyumov-Gerasimenko are compared to the velocities yielded by Whipple's model. The uncertainty intervals of the results are estimated.

Right ventricular strain in heart failure: Clinical perspective.

PubMed

Tadic, Marijana; Pieske-Kraigher, Elisabeth; Cuspidi, Cesare; Morris, Daniel A; Burkhardt, Franziska; Baudisch, Ana; Haßfeld, Sabine; Tschöpe, Carsten; Pieske, Burket

2017-10-01

The number of studies demonstrating the importance of right ventricular remodelling in a wide range of cardiovascular diseases has increased in the past two decades. Speckle-tracking imaging provides new variables that give comprehensive information about right ventricular function and mechanics. In this review, we summarize current knowledge of right ventricular mechanics in heart failure with reduced ejection fraction and preserved ejection fraction. We searched PubMed, MEDLINE, Ovid and Embase databases for studies published from January 2000 to December 2016 in the English language using the following keywords: "right ventricle"; "strain"; "speckle tracking"; "heart failure with reduced ejection fraction"; and "heart failure with preserved ejection fraction". Investigations showed that right ventricular dysfunction is associated with higher cardiovascular and overall mortality in patients with heart failure, irrespective of ejection fraction. The number of studies investigating right ventricular strain in patients with heart failure with reduced ejection fraction is constantly increasing, whereas data on right ventricular mechanics in patients with heart failure with preserved ejection fraction are limited. Given the high feasibility, accuracy and clinical implications of right ventricular strain in the population with heart failure, it is of great importance to try to include the evaluation of right ventricular strain as a regular part of each echocardiographic examination in patients with heart failure. However, further investigations are necessary to establish right ventricular strain as a standard variable for decision-making. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

On the hypothesis of hyperimpact-induced ejection of asteroid-size bodies from Earth-type planets.

NASA Astrophysics Data System (ADS)

Drobyshevski, E. M.

During the last two decades a number of facts have brought to life a seemingly fantastic idea of ejection of large rocky fragments from planets into space, like for example SNC meteorites or many-km-size fragments of Vesta. The theoretical description of impact processes of this ejection lags behind. Considerable efforts have been spent to show the possibility of ejection of bodies several meters in size from large impact craters on Mars. In general, the possibility of impact self-destruction of inner planets may drastically alter traditional models of the origin of the Solar System. However, non-destructive gasdynamic ejection of large fragments from planets requires a mechanism for fast conversion of shock-wave energy into heat. The extrapolation of data from laboratory impact experiments (≡10 kJ) and nuclear explosions (<1 Mt TNT) in order to describe hyperimpact processes with 105 - 106 Mt TNT energies can hardly be justified, that is why these calculations give relatively small gas production and, consequently, small velocities of fragment ejection from impact craters. It is predicted that at such energies some instabilities may lead to formation of new dissipation channels, that would increase the part of the overheated gas fraction in the hyperimpact ejection products. This would eliminate numerous contradictions in the impact history of planets, asteroids, meteorites etc.

Kinematic response of the spine during simulated aircraft ejections.

PubMed

Damon, Andrew M; Lessley, David J; Salzar, Robert S; Bass, Cameron R; Shen, Francis H; Paskoff, Glenn R; Shender, Barry S

2010-05-01

Military aviators are susceptible to spinal injuries during high-speed ejection scenarios. These injuries commonly arise as a result of strains induced by extreme flexion or compression of the spinal column. This study characterizes the vertebral motion of two postmortem human surrogates (PMHS) during a simulated catapult phase of ejection on a horizontal decelerator sled. During testing, the PMHS were restrained supinely to a mock ejection seat and subjected to a horizontal deceleration profile directed along the local z-axis. Two midsized males (175.3 cm, 77.1 kg; 185.4 cm, 72.6 kg) were tested. High-rate motion capture equipment was used to measure the three-dimensional displacement of the head, vertebrae, and pelvis during the ejection event. The two PMHS showed generally similar kinematic motion. Head injury criterion (HIC) results were well below injury threshold levels for both specimens. The specimens both showed compression of the spine, with a reduction in length of 23.9 mm and 45.7 mm. Post-test autopsies revealed fractures in the C5, T1, and L1 vertebrae. This paper provides an analysis of spinal motion during an aircraft ejection.The injuries observed in the test subjects were consistent with those seen in epidemiological studies. Future studies should examine the effects of gender, muscle tensing, out-of-position (of head from neutral position) occupants, and external forces (e.g., windblast) on spinal kinematics during aircraft ejection.

Rollover Car Crashes with Ejection: A Deadly Combination—An Analysis of 719 Patients

PubMed Central

Latifi, Rifat; El-Menyar, Ayman; El-Hennawy, Hany; Al-Thani, Hassan

2014-01-01

Rollover car crashes (ROCs) are serious public safety concerns worldwide. Objective. To determine the incidence and outcomes of ROCs with or without ejection of occupants in the State of Qatar. Methods. A retrospective study of all patients involved in ROCs admitted to Level I trauma center in Qatar (2011-2012). Patients were divided into Group I (ROC with ejection) and Group II (ROC without ejection). Results. A total of 719 patients were evaluated (237 in Group I and 482 in Group II). The mean age in Group I was lower than in Group II (24.3 ± 10.3 versus 29 ± 12.2; P = 0.001). Group I had higher injury severity score and sustained significantly more head, chest, and abdominal injuries in comparison to Group II. The mortality rate was higher in Group I (25% versus 7%; P = 0.001). Group I patients required higher ICU admission rate (P = 0.001). Patients in Group I had a 5-fold increased risk for age-adjusted mortality (OR 5.43; 95% CI 3.11–9.49), P = 0.001). Conclusion. ROCs with ejection are associated with higher rate of morbidity and mortality compared to ROCs without ejection. As an increased number of young Qatari males sustain ROCs with ejection, these findings highlight the need for research-based injury prevention initiatives in the country. PMID:24693231

Single- versus dual-rod anterior instrumentation of thoracolumbar curves in adolescent idiopathic scoliosis.

PubMed

Nambiar, Mithun; Yang, Yi; Liew, Susan; Turner, Peter L; Torode, Ian P

2016-10-01

Single or dual-rod instrumentation can be used for the anterior fixation of the spine in adolescent idiopathic scoliosis (AIS). We aim to compare the complications, radiographic and functional outcomes of patients with AIS who have undergone single and dual-rod instrumentation. This is a multi-centre study involving the Royal Children's, Royal Melbourne and Epworth hospitals. Three primary surgeons were involved to ensure homogeneity of surgical technique and implants. Patients with AIS and thoracolumbar curves (Lenke 5 and 6) undergoing anterior instrumentation from 1st January 2000 to 30th June 2013 were included. Radiographic data were collected from X-rays. The functional outcome was measured through the Scoliosis Research Society questionnaire (SRS-30). The study included 58 patients (38 single-rod and 20 dual-rod patients). Thirty-nine patients were classified with Lenke 5 curves, while 19 patients had Lenke 6 curves. Structural interbody supports were used in 95 % of cases. In the preoperative to postoperative period, patients with single rods had an improvement of 75 and 51 % for primary and secondary curves, respectively, while patients with dual rods had an improvement of 70 and 38 % for primary and secondary curves, respectively. There were no cases of pseudoarthrosis or metalware failure in either group. Two patients (one single-rod and one dual-rod patient) required further unplanned posterior fusion. 91 % of patients were satisfied with the results of their back management. Pseudoarthrosis and metalware failure are rare complications of anterior instrumentation. Our study found no significant difference in functional or radiographic outcome between single and dual-rod instrumentation. Level III.

In vivo optophysiology reveals that G-protein activation triggers osmotic swelling and increased light scattering of rod photoreceptors.

PubMed

Zhang, Pengfei; Zawadzki, Robert J; Goswami, Mayank; Nguyen, Phuong T; Yarov-Yarovoy, Vladimir; Burns, Marie E; Pugh, Edward N

2017-04-04

The light responses of rod and cone photoreceptors have been studied electrophysiologically for decades, largely with ex vivo approaches that disrupt the photoreceptors' subretinal microenvironment. Here we report the use of optical coherence tomography (OCT) to measure light-driven signals of rod photoreceptors in vivo. Visible light stimulation over a 200-fold intensity range caused correlated rod outer segment (OS) elongation and increased light scattering in wild-type mice, but not in mice lacking the rod G-protein alpha subunit, transducin (Gα t ), revealing these responses to be triggered by phototransduction. For stimuli that photoactivated one rhodopsin per Gα t the rod OS swelling response reached a saturated elongation of 10.0 ± 2.1%, at a maximum rate of 0.11% s -1 Analyzing swelling as osmotically driven water influx, we find the H 2 O membrane permeability of the rod OS to be (2.6 ± 0.4) × 10 -5 cm⋅s -1 , comparable to that of other cells lacking aquaporin expression. Application of Van't Hoff's law reveals that complete activation of phototransduction generates a potentially harmful 20% increase in OS osmotic pressure. The increased backscattering from the base of the OS is explained by a model combining cytoplasmic swelling, translocation of dissociated G-protein subunits from the disc membranes into the cytoplasm, and a relatively higher H 2 O permeability of nascent discs in the basal rod OS. Translocation of phototransduction components out of the OS may protect rods from osmotic stress, which could be especially harmful in disease conditions that affect rod OS structural integrity.

CNGA3 deficiency affects cone synaptic terminal structure and function and leads to secondary rod dysfunction and degeneration.

PubMed

Xu, Jianhua; Morris, Lynsie M; Michalakis, Stylianos; Biel, Martin; Fliesler, Steven J; Sherry, David M; Ding, Xi-Qin

2012-03-01

To investigate rod function and survival after cone dysfunction and degeneration in a mouse model of cone cyclic nucleotide-gated (CNG) channel deficiency. Rod function and survival in mice with cone CNG channel subunit CNGA3 deficiency (CNGA3-/- mice) were evaluated by electroretinographic (ERG), morphometric, and Western blot analyses. The arrangement, integrity, and ultrastructure of photoreceptor terminals were investigated by immunohistochemistry and electron microscopy. The authors found loss of cone function and cone death accompanied by impairment of rods and rod-driven signaling in CNGA3-/- mice. Scotopic ERG b-wave amplitudes were reduced by 15% at 1 month, 30% at 6 months, and 40% at 9 months and older, while scotopic a-wave amplitudes were decreased by 20% at 9 months, compared with ERGs of age-matched wild-type mice. Outer nuclear layer thickness in CNGA3-/- retina was reduced by 15% at 12 months compared with age-matched wild-type controls. This was accompanied by a 30%-40% reduction in expression of rod-specific proteins, including rhodopsin, rod transducin α-subunit, and glutamic acid-rich protein (GARP). Cone terminals in the CNGA3-/- retina showed a progressive loss of neurochemical and ultrastructural integrity. Abnormalities were observed as early as 1 month. Disorganized rod terminal ultrastructure was noted by 12 months. These findings demonstrate secondary rod impairment and degeneration after cone degeneration in mice with cone CNG channel deficiency. Loss of cone phototransduction accompanies the compromised integrity of cone terminals. With time, rod synaptic structure, function, and viability also become compromised.

Rod Electroretinograms Elicited by Silent Substitution Stimuli from the Light-Adapted Human Eye

PubMed Central

Maguire, John; Parry, Neil R. A.; Kremers, Jan; Kommanapalli, Deepika; Murray, Ian J.; McKeefry, Declan J.

2016-01-01

Purpose To demonstrate that silent substitution stimuli can be used to generate electroretinograms (ERGs) that effectively isolate rod photoreceptor function in humans without the need for dark adaptation, and that this approach constitutes a viable alternative to current clinical standard testing protocols. Methods Rod-isolating and non-isolating sinusoidal flicker stimuli were generated on a 4 primary light-emitting diode (LED) Ganzfeld stimulator to elicit ERGs from participants with normal and compromised rod function who had not undergone dark-adaptation. Responses were subjected to Fourier analysis, and the amplitude and phase of the fundamental were used to examine temporal frequency and retinal illuminance response characteristics. Results Electroretinograms elicited by rod-isolating silent substitution stimuli exhibit low-pass temporal frequency response characteristics with an upper response limit of 30 Hz. Responses are optimal between 5 and 8 Hz and between 10 and 100 photopic trolands (Td). There is a significant correlation between the response amplitudes obtained with the silent substitution method and current standard clinical protocols. Analysis of signal-to-noise ratios reveals significant differences between subjects with normal and compromised rod function. Conclusions Silent substitution provides an effective method for the isolation of human rod photoreceptor function in subjects with normal as well as compromised rod function when stimuli are used within appropriate parameter ranges. Translational Relevance This method of generating rod-mediated ERGs can be achieved without time-consuming periods of dark adaptation, provides improved isolation of rod- from cone-based activity, and will lead to the development of faster clinical electrophysiologic testing protocols with improved selectivity. PMID:27617180

Intraspinal canal rod migration causing late-onset paraparesis 8 years after scoliosis surgery.

PubMed

Obeid, Ibrahim; Vital, Jean-Marc; Aurouer, Nicolas; Hansen, Steve; Gangnet, Nicolas; Pointillart, Vincent; Gille, Olivier; Boissiere, Louis; Quraishi, Nasir A

2016-07-01

Complete intraspinal canal rod migration with posterior bone reconstitution has never been described in the adolescent idiopathic scoliosis (AIS) population. We present an unusual but significant delayed neurological complication after spinal instrumentation surgery. A 24-year-old woman presented with lower limb weakness (ASIA D) 8 years after posterior instrumentation from T2 to L4 for AIS. CT scan and MRI demonstrated intra-canal rod migration with complete laminar reconstitution. The C-reactive protein was slightly elevated (fluctuated between 10 and 20 mg/l). Radiographs showed the convex rod had entered the spinal canal. The patient was taken into the operating room for thoracic spinal decompression and removal of the convex rod. This Cotrel-Dubousset rod, which had been placed on the convexity of the thoracic curve had completely entered the canal from T5 to T10 and was totally covered by bone with the eroded laminae entirely healed and closed. There was no pseudarthrosis. Intra-operatively, the fusion mass was opened along the whole length of this rod and the rod carefully removed and the spinal cord decompressed. The bacteriological cultures returned positive for Propionibacterium acnes. The patient recovered fully within 2 months post-operatively. We opine that the progressive laminar erosion with intra-canal rod migration resulted from mechanical and infectious-related factors. The very low virulence of the strain of Propionibacterium acnes is probably involved in this particular presentation where the rod was trapped in the canal, owing to the quite extensive laminar reconstitution.

Thermoreversible Gels Composed of Colloidal Silica Rods with Short-Range Attractions

DOE PAGES

Murphy, Ryan P.; Hong, Kunlun; Wagner, Norman J.

2016-07-28

Dynamic arrest transitions of colloidal suspensions containing non-spherical particles are of interest for the design and processing of various particle technologies. To better understand the effects of particle shape anisotropy and attraction strength on gel and glass formation, we present a colloidal model system of octadecyl-coated silica rods, termed as adhesive hard rods (AHR), which enables control of rod aspect ratio and temperature-dependent interactions. The aspect ratios of silica rods were controlled by varying the initial TEOS concentration following the work of Kuijk et al. (J. Am. Chem. Soc., 2011, 133, 2346–2349) and temperature-dependent attractions were introduced by coating themore » calcined silica rods with an octadecyl-brush and suspending in tetradecane. The rod length and aspect ratio were found to increase with TEOS concentration as expected, while other properties such as the rod diameter, coating coverage, density, and surface roughness were nearly independent of the aspect ratio. Ultra-small angle X-ray scattering measurements revealed temperature-dependent attractions between octadecyl-coated silica rods in tetradecane, as characterized by a low-q upturn in the scattered intensity upon thermal quenching. Lastly, the rheology of a concentrated AHR suspension in tetradecane demonstrated thermoreversible gelation behavior, displaying a nearly 5 orders of magnitude change in the dynamic moduli as the temperature was cycled between 15 and 40 °C. We find the adhesive hard rod model system serves as a tunable platform to explore the combined influence of particle shape anisotropy and attraction strength on the dynamic arrest transitions in colloidal suspensions with thermoreversible, short-range attractions.« less

ZnO Nano-Rod Devices for Intradermal Delivery and Immunization.

PubMed

Nayak, Tapas R; Wang, Hao; Pant, Aakansha; Zheng, Minrui; Junginger, Hans; Goh, Wei Jiang; Lee, Choon Keong; Zou, Shui; Alonso, Sylvie; Czarny, Bertrand; Storm, Gert; Sow, Chorng Haur; Lee, Chengkuo; Pastorin, Giorgia

2017-06-15

Intradermal delivery of antigens for vaccination is a very attractive approach since the skin provides a rich network of antigen presenting cells, which aid in stimulating an immune response. Numerous intradermal techniques have been developed to enhance penetration across the skin. However, these methods are invasive and/or affect the skin integrity. Hence, our group has devised zinc oxide (ZnO) nano-rods for non-destructive drug delivery. Chemical vapour deposition was used to fabricate aligned nano-rods on ZnO pre-coated silicon chips. The nano-rods' length and diameter were found to depend on the temperature, time, quality of sputtered silicon chips, etc. Vertically aligned ZnO nano-rods with lengths of 30-35 µm and diameters of 200-300 nm were selected for in vitro human skin permeation studies using Franz cells with Albumin-fluorescein isothiocyanate (FITC) absorbed on the nano-rods. Fluorescence and confocal studies on the skin samples showed FITC penetration through the skin along the channels formed by the nano-rods. Bradford protein assay on the collected fluid samples indicated a significant quantity of Albumin-FITC in the first 12 h. Low antibody titres were observed with immunisation on Balb/c mice with ovalbumin (OVA) antigen coated on the nano-rod chips. Nonetheless, due to the reduced dimensions of the nano-rods, our device offers the additional advantage of excluding the simultaneous entrance of microbial pathogens. Taken together, these results showed that ZnO nano-rods hold the potential for a safe, non-invasive, and painless intradermal drug delivery.

Enhanced Photocatalytic Activity of Bismuth Precursor by Rapid Phase and Surface Transformation Using Structure-Guided Combustion Waves.

PubMed

Lee, Kang Yeol; Hwang, Hayoung; Kim, Tae Ho; Choi, Wonjoon

2016-02-10

The development of an efficient method for manipulating phase and surface transformations would facilitate the improvement of catalytic materials for use in a diverse range of applications. Herein, we present the first instance of a submicrosecond time frame direct phase and surface transformation of Bi(NO3)3 rods to nanoporous β-Bi2O3 rods via structure-guided combustion waves. Hybrid composites of the prepared Bi(NO3)3·H2O rods and organic fuel were fabricated by a facile preparation method. The anisotropic propagation of combustion waves along the interfacial boundaries of Bi(NO3)3·H2O rods induced direct phase transformation to β-Bi2O3 rods in the original structure due to the rapid pyrolysis, while the release of gas molecules enabled the formation of nanoporous structures on the surfaces of rods. The developed β-Bi2O3 rods showed improved photocatalytic activity for the photodegradation of rhodamine B in comparison with Bi(NO3)3·H2O rods and α-Bi2O3 rods due to the more suitable interdistance and the large contact areas of the porous surfaces. This new method of using structure-guided combustion waves for phase and surface transformation may contribute to the development of new catalysts as well as the precise manipulation of diverse micronanostructured materials.

Ectopic expression of cone-specific G-protein-coupled receptor kinase GRK7 in zebrafish rods leads to lower photosensitivity and altered responses

PubMed Central

Vogalis, F; Shiraki, T; Kojima, D; Wada, Y; Nishiwaki, Y; Jarvinen, J L P; Sugiyama, J; Kawakami, K; Masai, I; Kawamura, S; Fukada, Y; Lamb, T D

2011-01-01

Abstract To investigate the roles of G-protein receptor kinases (GRKs) in the light responses of vertebrate photoreceptors, we generated transgenic zebrafish lines, the rods of which express either cone GRK (GRK7) or rod GRK (GRK1) in addition to the endogenous GRK1, and we then measured the electrophysiological characteristics of single-cell responses and the behavioural responses of intact animals. Our study establishes the zebrafish expression system as a convenient platform for the investigation of specific components of the phototransduction cascade. The addition of GRK1 led to minor changes in rod responses. However, exogenous GRK7 in GRK7-tg animals led to lowered rod sensitivity, as occurs in cones, but surprisingly to slower response kinetics. Examination of responses to long series of very dim flashes suggested the possibility that the GRK7-tg rods generated two classes of single-photon response, perhaps corresponding to the interaction of activated rhodopsin with GRK1 (giving a standard response) or with GRK7 (giving a very small response). Behavioural measurement of optokinetic responses (OKR) in intact GRK7-tg zebrafish larvae showed that the overall rod visual pathway was less sensitive, in accord with the lowered sensitivity of the rods. These results help provide an understanding for the molecular basis of the electrophysiological differences between cones and rods. PMID:21486791

Noise reduction in a Mach 5 wind tunnel with a rectangular rod-wall sound shield

NASA Technical Reports Server (NTRS)

Creel, T. R., Jr.; Keyes, J. W.; Beckwith, I. E.

1980-01-01

A rod wall sound shield was tested over a range of Reynolds numbers of 0.5 x 10 to the 7th power to 8.0 x 10 to the 7th power per meter. The model consisted of a rectangular array of longitudinal rods with boundary-layer suction through gaps between the rods. Suitable measurement techniques were used to determine properties of the flow and acoustic disturbance in the shield and transition in the rod boundary layers. Measurements indicated that for a Reynolds number of 1.5 x 10 to the 9th power the noise in the shielded region was significantly reduced, but only when the flow is mostly laminar on the rods. Actual nozzle input noise measured on the nozzle centerline before reflection at the shield walls was attenuated only slightly even when the rod boundary layer were laminar. At a lower Reynolds number, nozzle input noise at noise levels in the shield were still too high for application to a quiet tunnel. At Reynolds numbers above 2.0 x 10 the the 7th power per meter, measured noise levels were generally higher than nozzle input levels, probably due to transition in the rod boundary layers. The small attenuation of nozzle input noise at intermediate Reynolds numbers for laminar rod layers at the acoustic origins is apparently due to high frequencies of noise.

A preliminary investigation of shape memory alloys in the surgical correction of scoliosis.

PubMed

Sanders, J O; Sanders, A E; More, R; Ashman, R B

1993-09-15

Nitinol, a shape memory alloy, is flexible at low temperatures but retains its original shape when heated. This offers interesting possibilities for scoliosis correction. Of the shape memory alloys, nitinol is the most promising medically because of biocompatibility and the ability to control transition temperature. In vivo: Six goats with experimental scoliosis were instrumented with 6-mm nitinol rods. The rods were transformed, and the scoliosis corrected, in the awakened goats by 450-kHz radio frequency induction heating. The curves averaged 41 degrees before instrumentation, 33 degrees after instrumentation, and 11 degrees after rod transformation. The animals tolerated the heating without discomfort, neurologic injury, or evidence of thermal injury to the tissues or the spinal cord. In vitro: Nitinol rods were tested under both constant deflection and constant loading conditions and plotted temperature versus either force or displacement. The 6-mm rod generated forces of 200 N. The 9-mm rod generated up to 500 N. We safely coupled shape memory alloy transformation to the spine and corrected an experimental spinal deformity in awake animals. The forces generated can be estimated by the rod's curvature and temperature. The use of shape memory alloys allows continuous neurologic monitoring during awake correction, true rotational correction by rod torsion, and the potential option of periodic correction to take advantage of spinal viscoelasticity and the potential of true rotational correction by rod torsion.

Maintaining a Critical Spectra within Monteburns for a Gas-Cooled Reactor Array by Way of Control Rod Manipulation

DOE PAGES

Adigun, Babatunde John; Fensin, Michael Lorne; Galloway, Jack D.; ...

2016-10-01

Our burnup study examined the effect of a predicted critical control rod position on the nuclide predictability of several axial and radial locations within a 4×4 graphite moderated gas cooled reactor fuel cluster geometry. To achieve this, a control rod position estimator (CRPE) tool was developed within the framework of the linkage code Monteburns between the transport code MCNP and depletion code CINDER90, and four methodologies were proposed within the tool for maintaining criticality. Two of the proposed methods used an inverse multiplication approach - where the amount of fissile material in a set configuration is slowly altered until criticalitymore » is attained - in estimating the critical control rod position. Another method carried out several MCNP criticality calculations at different control rod positions, then used a linear fit to estimate the critical rod position. The final method used a second-order polynomial fit of several MCNP criticality calculations at different control rod positions to guess the critical rod position. The results showed that consistency in prediction of power densities as well as uranium and plutonium isotopics was mutual among methods within the CRPE tool that predicted critical position consistently well. Finall, while the CRPE tool is currently limited to manipulating a single control rod, future work could be geared toward implementing additional criticality search methodologies along with additional features.« less

Comparing the Performance of Hyperbolic and Circular Rod Quadrupole Mass Spectrometers with Applied Higher Order Auxiliary Excitation

NASA Technical Reports Server (NTRS)

Gershman, D.J.; Block, B.P.; Rubin, M.; Benna, M.; Mahaffy, P. R.; Zurbuchen, T. H.

2012-01-01

This work applies higher order auxiliary excitation techniques to two types of quadrupole mass spectrometers (QMSs): commercial systems and spaceborne instruments. The operational settings of a circular rod geometry commercial system and an engineering test-bed for a hyperbolic rod geometry spaceborne instrument were matched, with the relative performance of each sensor characterized with and without applied excitation using isotopic measurements of Kr+. Each instrument was operated at the limit of the test electronics to determine the effect of auxiliary excitation on extending instrument capabilities. For the circular rod sensor, with applied excitation, a doubling of the mass resolution at 1% of peak transmission resulted from the elimination of the low-mass side peak tail typical of such rod geometries. The mass peak stability and ion rejection efficiency were also increased by factors of 2 and 10, respectively, with voltage scan lines passing through the center of stability islands formed from auxiliary excitation. Auxiliary excitation also resulted in factors of 6 and 2 in peak stability and ion rejection efficiency, respectively, for the hyperbolic rod sensor. These results not only have significant implications for the use of circular rod quadrupoles with applied excitation as a suitable replacement for traditional hyperbolic rod sensors, but also for extending the capabilities of existing hyperbolic rod QMSs for the next generation of spaceborne instruments and low-mass commercial systems.

Hypoxic preconditioning protects photoreceptors against light damage independently of hypoxia inducible transcription factors in rods.

PubMed

Kast, Brigitte; Schori, Christian; Grimm, Christian

2016-05-01

Hypoxic preconditioning protects photoreceptors against light-induced degeneration preserving retinal morphology and function. Although hypoxia inducible transcription factors 1 and 2 (HIF1, HIF2) are the main regulators of the hypoxic response, photoreceptor protection does not depend on HIF1 in rods. Here we used rod-specific Hif2a single and Hif1a;Hif2a double knockout mice to investigate the potential involvement of HIF2 in rods for protection after hypoxic preconditioning. To identify potential HIF2 target genes in rods we determined the retinal transcriptome of hypoxic control and rod-specific Hif2a knockouts by RNA sequencing. We show that rods do not need HIF2 for hypoxia-induced increased survival after light exposure. The transcriptomic analysis revealed a number of genes that are potentially regulated by HIF2 in rods; among those were Htra1, Timp3 and Hmox1, candidates that are interesting due to their connection to human degenerative diseases of the retina. We conclude that neither HIF1 nor HIF2 are required in photoreceptors for protection by hypoxic preconditioning. We hypothesize that HIF transcription factors may be needed in other cells to produce protective factors acting in a paracrine fashion on photoreceptor cells. Alternatively, hypoxic preconditioning induces a rod-intrinsic response that is independent of HIF transcription factors. Copyright © 2015 Elsevier Ltd. All rights reserved.

Multispecies exclusion process with fusion and fission of rods: A model inspired by intraflagellar transport

NASA Astrophysics Data System (ADS)

Patra, Swayamshree; Chowdhury, Debashish

2018-01-01

We introduce a multispecies exclusion model where length-conserving probabilistic fusion and fission of the hard rods are allowed. Although all rods enter the system with the same initial length ℓ =1 , their length can keep changing, because of fusion and fission, as they move in a step-by-step manner towards the exit. Two neighboring hard rods of lengths ℓ1 and ℓ2 can fuse into a single rod of longer length ℓ =ℓ1+ℓ2 provided ℓ ≤N . Similarly, length-conserving fission of a rod of length ℓ'≤N results in two shorter daughter rods. Based on the extremum current hypothesis, we plot the phase diagram of the model under open boundary conditions utilizing the results derived for the same model under periodic boundary condition using mean-field approximation. The density profile and the flux profile of rods are in excellent agreement with computer simulations. Although the fusion and fission of the rods are motivated by similar phenomena observed in intraflagellar transport (IFT) in eukaryotic flagella, this exclusion model is too simple to account for the quantitative experimental data for any specific organism. Nevertheless, the concepts of "flux profile" and "transition zone" that emerge from the interplay of fusion and fission in this model are likely to have important implications for IFT and for other similar transport phenomena in long cell protrusions.

Effects of a telescopic intramedullary rod for treating patients with osteogenesis imperfecta of the femur

PubMed Central

Rosemberg, D. L.; Goiano, E. O.; Akkari, M.; Santili, C.

2018-01-01

Abstract Purpose To introduce a new model of telescopic intramedullary rod (TIR), evaluate its effects on treating patients presenting with moderate and severe osteogenesis imperfecta (OI) and to compare the findings with those of other telescopic rods. Methods A total of 21 patients (nine girls and 12 boys; mean age at first operation, 6.6 years, 1.52 to 13.18) who underwent 52 femoral operations were monitored during a mean of 9.96 years (3.39 to 14.54). Patient characteristics, telescoping rod capability and its complications were examined. Results According to the Sillence classification, we investigated one patient with type I, nine with type III and 11 with type IV OI. Revision rates at up to five years (36%) were inferior to those found for the Fassier-Duval rod (46%). The main cause of revision was fracture (15 patients), followed by rod migration (nine), and infection (two). The rod exhibited higher telescopic capacity in boys than girls. Type III most commonly required an operation; the age group with the highest number of procedures was five to ten years. Male migration was the main cause of rod migration. Conclusion The TIR has a satisfactory cost-benefit ratio with less complication rates and low production costs. The TIR is a feasible alternative to the commonly used Fassier-Duval rod. Level of Evidence IV PMID:29456761

Microcapsules ejecting nanosized species into the environment.

PubMed

De Geest, Bruno G; McShane, Michael J; Demeester, Jo; De Smedt, Stefaan C; Hennink, Wim E

2008-11-05

In this communication we report on microcapsules which eject nanoparticles into the environment. The speed of the nanoparticles ejected in water is approximately 800-fold faster than their Brownian diffusion. Such microcarriers may allow nanosized species to travel long distances, in short times, through highly viscous environments and may find applications in e.g. drug delivery and tissue engineering.

Long stroke pump

NASA Technical Reports Server (NTRS)

Perkins, Gerald S. (Inventor); Moore, Nicholas R. (Inventor)

1979-01-01

A very high pressure pump apparatus which minimizes wear on the seals thereof and on valves connected thereto, by utilizing a very long stroke piston rod whose opposite ends are received in long cylinders. An electric motor which drives the rod, includes a rotor with a threaded aperture that receives a long threaded middle portion of the rod, so that as the rotor turns it advances the rod.

75 FR 30899 - Notice of a Finding of No Significant Impact (FONSI) and Record of Decision (ROD) on a Final...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-06-02

... Impact (FONSI) and Record of Decision (ROD) on a Final Environmental Assessment (FEA) for the Proposed.../ROD on an FEA for a proposed Federal action at the Macon County Airport, Franklin, NC. The FONSI/ROD... will not significantly affect the quality of the environment. The FEA evaluated Macon County Airport's...

78 FR 48543 - Notice of Approval of Finding of No Significant Impact-Record of Decision (FONSI/ROD) for Sioux...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-08-08

... Significant Impact--Record of Decision (FONSI/ROD) for Sioux Falls Regional Airport, Sioux Falls, South Dakota... approval of Finding of No Significant Impact--Record of Decision (FONSI/ROD) for proposed development at the Sioux Falls Regional Airport, Sioux Falls, South Dakota. The FAA approved the FONSI/ROD on July 22...

POSITIONING DEVICE

DOEpatents

McCorkle, W.H.

1959-07-14

A positioner for a control rod for a nuclear reactor is described. The positioner includes a spur gear and rack for adjusting the control rod slowly and in small ainounts as well as a piston and cylinder for moving the control rod rapidly thrcugh larger distances. The positioner also has associsted with it a worm wheel and gear for rotating it out of engagement with the control rod.

THERMAL COUPLE FOR MEASURING TEMPERATURE IN A REACTOR

DOEpatents

Kanne, W.

1959-11-24

A thermocouple device for measuring the temperature of a flowing fluid in a conduit within which is positioned a metallic rod is presented. A thermocouple junction is secured to the rod centrally, and thermal insulating support disks having a diameter greater than the rod are secured to the end portions of the rod and adapted to fit transversely in the conduit.

CONTROL ROD DRIVE MECHANISM FOR A NUCLEAR REACTOR

DOEpatents

Hawke, B.C.; Liederbach, F.J.; Lones, W.

1963-05-14

A lead-screw-type control rod drive featuring an electric motor and a fluid motor arranged to provide a selectably alternative driving means is described. The electric motor serves to drive the control rod slowly during normal operation, while the fluid motor, assisted by an automatic declutching of the electric motor, affords high-speed rod insertion during a scram. (AEC)

76 FR 67672 - Certain Stainless Steel Wire Rods From India: Final Results of the Expedited Sunset Review of the...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-11-02

... DEPARTMENT OF COMMERCE International Trade Administration [A-533-808] Certain Stainless Steel Wire... duty order on certain stainless steel wire rods from India, pursuant to section 751(c) of the [[Page... antidumping duty order on certain stainless steel wire rods from India (wire rods) \\1\\ pursuant to section 751...

75 FR 34424 - Stainless Steel Wire Rod from Italy, Japan, the Republic of Korea, Spain, and Taiwan...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-06-17

...-807, A-583-828] Stainless Steel Wire Rod from Italy, Japan, the Republic of Korea, Spain, and Taiwan... stainless steel wire rod (SSWR) from Italy, Japan, the Republic of Korea (Korea), Spain, and Taiwan would... magnitude of the margins likely to prevail should the orders be revoked. See Stainless Steel Wire Rod From...

78 FR 60850 - Carbon and Certain Alloy Steel Wire Rod From Brazil: Final Results of the Expedited Second Sunset...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-10-02

... Steel Wire Rod From Brazil: Final Results of the Expedited Second Sunset Review of the Countervailing... of the countervailing duty (CVD) order on carbon and certain alloy steel wire rod (wire rod) from...: Background On June 3, 2013, the Department initiated the second sunset review of the CVD order \\1\\ on wire...

Development of rod function in term born and former preterm subjects.

PubMed

Fulton, Anne B; Hansen, Ronald M; Moskowitz, Anne

2009-06-01

To provide an overview of some of our electroretinographic (ERG) and psychophysical studies of normal development of rod function and their application to retinopathy of prematurity (ROP). ERG responses to full-field stimuli were recorded from dark adapted subjects. Rod photoreceptor sensitivity (SROD) was calculated by fit of a biochemical model of the activation of phototransduction to the ERG a-wave. Dark adapted psychophysical thresholds for detecting 2 degrees spots in parafoveal (10 degrees eccentric) and peripheral (30 degrees eccentric) retina were measured and the difference between the thresholds, Delta10-30, was examined as a function of age. SROD and Delta10-30 in term born and former preterm subjects were compared. In term born infants, (1) the normal developmental increase in SROD changes proportionately with the amount of rod visual pigment, rhodopsin, and (2) rod-mediated function in central retina is immature compared with that in peripheral retina. In subjects born prematurely, deficits in SROD persist long after active ROP has resolved. Maturation of rod-mediated thresholds in the central retina is prolonged by mild ROP. Characterization of the development of normal rod and rod-mediated function provides a foundation for understanding ROP.

Periodic dielectric structure for production of photonic band gap and devices incorporating the same

DOEpatents

Ho, Kai-Ming; Chan, Che-Ting; Soukoulis, Costas

1994-08-02

A periodic dielectric structure which is capable of producing a photonic band gap and which is capable of practical construction. The periodic structure is formed of a plurality of layers, each layer being formed of a plurality of rods separated by a given spacing. The material of the rods contrasts with the material between the rods to have a refractive index contrast of at least two. The rods in each layer are arranged with their axes parallel and at a given spacing. Adjacent layers are rotated by 90.degree., such that the axes of the rods in any given layer are perpendicular to the axes in its neighbor. Alternating layers (that is, successive layers of rods having their axes parallel such as the first and third layers) are offset such that the rods of one are about at the midpoint between the rods of the other. A four-layer periocity is thus produced, and successive layers are stacked to form a three-dimensional structure which exhibits a photonic band gap. By virtue of forming the device in layers of elongate members, it is found that the device is susceptible of practical construction.

On-line detection of key radionuclides for fuel-rod failure in a pressurized water reactor.

PubMed

Qin, Guoxiu; Chen, Xilin; Guo, Xiaoqing; Ni, Ning

2016-08-01

For early on-line detection of fuel rod failure, the key radionuclides useful in monitoring must leak easily from failing rods. Yield, half-life, and mass share of fission products that enter the primary coolant also need to be considered in on-line analyses. From all the nuclides that enter the primary coolant during fuel-rod failure, (135)Xe and (88)Kr were ultimately chosen as crucial for on-line monitoring of fuel-rod failure. A monitoring system for fuel-rod failure detection for pressurized water reactor (PWR) based on the LaBr3(Ce) detector was assembled and tested. The samples of coolant from the PWR were measured using the system as well as a HPGe γ-ray spectrometer. A comparison showed the method was feasible. Finally, the γ-ray spectra of primary coolant were measured under normal operations and during fuel-rod failure. The two peaks of (135)Xe (249.8keV) and (88)Kr (2392.1keV) were visible, confirming that the method is capable of monitoring fuel-rod failure on-line. Copyright © 2016 Elsevier Ltd. All rights reserved.

Six hydrophobins are involved in hydrophobin rodlet formation in Aspergillus nidulans and contribute to hydrophobicity of the spore surface.

PubMed

Grünbacher, André; Throm, Tanja; Seidel, Constanze; Gutt, Beatrice; Röhrig, Julian; Strunk, Timo; Vincze, Paul; Walheim, Stefan; Schimmel, Thomas; Wenzel, Wolfgang; Fischer, Reinhard

2014-01-01

Hydrophobins are amphiphilic proteins able to self-assemble at water-air interphases and are only found in filamentous fungi. In Aspergillus nidulans two hydrophobins, RodA and DewA, have been characterized, which both localize on the conidiospore surface and contribute to its hydrophobicity. RodA is the constituent protein of very regularly arranged rodlets, 10 nm in diameter. Here we analyzed four more hydrophobins, DewB-E, in A. nidulans and found that all six hydrophobins contribute to the hydrophobic surface of the conidiospores but only deletion of rodA caused loss of the rodlet structure. Analysis of the rodlets in the dewB-E deletion strains with atomic force microscopy revealed that the rodlets appeared less robust. Expression of DewA and DewB driven from the rodA promoter and secreted with the RodA secretion signal in a strain lacking RodA, restored partly the hydrophobicity. DewA and B were able to form rodlets to some extent but never reached the rodlet structure of RodA. The rodlet-lacking rodA-deletion strain opens the possibility to systematically study rodlet formation of other natural or synthetic hydrophobins.

Six Hydrophobins Are Involved in Hydrophobin Rodlet Formation in Aspergillus nidulans and Contribute to Hydrophobicity of the Spore Surface

PubMed Central

Seidel, Constanze; Gutt, Beatrice; Röhrig, Julian; Strunk, Timo; Vincze, Paul; Walheim, Stefan; Schimmel, Thomas; Wenzel, Wolfgang; Fischer, Reinhard

2014-01-01

Hydrophobins are amphiphilic proteins able to self-assemble at water-air interphases and are only found in filamentous fungi. In Aspergillus nidulans two hydrophobins, RodA and DewA, have been characterized, which both localize on the conidiospore surface and contribute to its hydrophobicity. RodA is the constituent protein of very regularly arranged rodlets, 10 nm in diameter. Here we analyzed four more hydrophobins, DewB-E, in A. nidulans and found that all six hydrophobins contribute to the hydrophobic surface of the conidiospores but only deletion of rodA caused loss of the rodlet structure. Analysis of the rodlets in the dewB-E deletion strains with atomic force microscopy revealed that the rodlets appeared less robust. Expression of DewA and DewB driven from the rodA promoter and secreted with the RodA secretion signal in a strain lacking RodA, restored partly the hydrophobicity. DewA and B were able to form rodlets to some extent but never reached the rodlet structure of RodA. The rodlet-lacking rodA-deletion strain opens the possibility to systematically study rodlet formation of other natural or synthetic hydrophobins. PMID:24722460

High energy, low frequency, ultrasonic transducer

DOEpatents

Brown, Albert E.

2000-01-01

A wide bandwidth, ultrasonic transducer to generate nondispersive, extensional, pulsed acoustic pressure waves into concrete reinforced rods and tendons. The wave propagation distance is limited to double the length of the rod. The transducer acoustic impedance is matched to the rod impedance for maximum transfer of acoustic energy. The efficiency of the transducer is approximately 60 percent, depending upon the type of active elements used in the transducer. The transducer input energy is, for example, approximately 1 mJ. Ultrasonic reflections will occur at points along the rod where there are changes of one percent of a wavelength in the rod diameter. A reduction in the rod diameter will reflect a phase reversed echo, as compared with the reflection from an incremental increase in diameter. Echo signal processing of the stored waveform permits a reconstruction of those echoes into an image of the rod. The ultrasonic transducer has use in the acoustic inspection of long (40+foot) architectural reinforcements and structural supporting members, such as in bridges and dams.

Mouse rods signal through gap junctions with cones.

PubMed

Asteriti, Sabrina; Gargini, Claudia; Cangiano, Lorenzo

2014-01-01

Rod and cone photoreceptors are coupled by gap junctions (GJs), relatively large channels able to mediate both electrical and molecular communication. Despite their critical location in our visual system and evidence that they are dynamically gated for dark/light adaptation, the full impact that rod-cone GJs can have on cone function is not known. We recorded the photovoltage of mouse cones and found that the initial level of rod input increased spontaneously after obtaining intracellular access. This process allowed us to explore the underlying coupling capacity to rods, revealing that fully coupled cones acquire a striking rod-like phenotype. Calcium, a candidate mediator of the coupling process, does not appear to be involved on the cone side of the junctional channels. Our findings show that the anatomical substrate is adequate for rod-cone coupling to play an important role in vision and, possibly, in biochemical signaling among photoreceptors. DOI: http://dx.doi.org/10.7554/eLife.01386.001.

MreB filaments align along greatest principal membrane curvature to orient cell wall synthesis

PubMed Central

Szwedziak, Piotr; Wong, Felix; Schaefer, Kaitlin; Izoré, Thierry; Renner, Lars D; Holmes, Matthew J; Sun, Yingjie; Bisson-Filho, Alexandre W; Walker, Suzanne; Amir, Ariel; Löwe, Jan

2018-01-01

MreB is essential for rod shape in many bacteria. Membrane-associated MreB filaments move around the rod circumference, helping to insert cell wall in the radial direction to reinforce rod shape. To understand how oriented MreB motion arises, we altered the shape of Bacillus subtilis. MreB motion is isotropic in round cells, and orientation is restored when rod shape is externally imposed. Stationary filaments orient within protoplasts, and purified MreB tubulates liposomes in vitro, orienting within tubes. Together, this demonstrates MreB orients along the greatest principal membrane curvature, a conclusion supported with biophysical modeling. We observed that spherical cells regenerate into rods in a local, self-reinforcing manner: rapidly propagating rods emerge from small bulges, exhibiting oriented MreB motion. We propose that the coupling of MreB filament alignment to shape-reinforcing peptidoglycan synthesis creates a locally-acting, self-organizing mechanism allowing the rapid establishment and stable maintenance of emergent rod shape. PMID:29469806

Evaluation of ceramic packed-rod regenerator matrices

NASA Technical Reports Server (NTRS)

Lawless, W. N.; Arenz, R. W.

1981-01-01

An extensive evaluation of a modified cryocooler with various regenerator matrices is reported. The matrices examined are 0.015 in. diam. Pb spheres and 0.008, 0.015, and 0.030 in. diam. rods of a 0.2% SnCl2 doped ceramic labelled LS-8A. Specific heat and thermal conductivity data on these rod materials are also reported. The chronic pulverization/dusting problem common to Pb spheres was investigated. During a 1000 hr life test with 0.0008 in. diam. rods there was no degradation of the refrigerator performance, and a subsequent examination of the rods themselves revealed no evidence of breakage or pulverization. The load temperature characteristics for the rod packed regenerators were inferior to that for the Pb spheres, the effect being to shift the Pb spheres load curve up in temperature. This temperature shift was 5.0, 7.4, and 11.6K for the 0.0008, 0.015, and 0.030 in. diam. rods, respectively.

Optimal Navigation of Self-Propelled Colloids in Microstructured Mazes

NASA Astrophysics Data System (ADS)

Yang, Yuguang; Bevan, Michael

Controlling navigation of self-propelled microscopic `robots' subject to random Brownian motion in complex microstructured environments (e.g., porous media, tumor vasculature) is important to many emerging applications (e.g., enhanced oil recovery, drug delivery). In this work, we design an optimal feedback policy to navigate an active self-propelled colloidal rod in complex mazes with various obstacle types. Actuation of the rods is modelled based on a light-controlled osmotic flow mechanism, which produces different propulsion velocities along the rod's long axis. Actuator-parameterized Langevin equations, with soft rod-obstacle repulsive interactions, are developed to describe the system dynamics. A Markov decision process (MDP) framework is used for optimal policy calculations with design goals of colloidal rods reaching target end points in minimum time. Simulations show that optimal MDP-based policies are able to control rod trajectories to reach target regions order-of-magnitudes faster than uncontrolled rods, which diverges as maze complexity increases. An efficient multi-graph based implementation for MDP is also presented, which scales linearly with the maze dimension.

Electric circuit breaker comprising a plurality of vacuum interrupters simultaneously operated by a common operator

DOEpatents

Barkan, Philip; Imam, Imdad

1980-01-01

This circuit breaker comprises a plurality of a vacuum-type circuit interrupters, each having a movable contact rod. A common operating device for the interrupters comprises a linearly-movable operating member. The interrupters are mounted at one side of the operating member with their movable contact rods extending in a direction generally toward the operating member. Means is provided for mechanically coupling the operating member to the contact rods, and this means comprises a plurality of insulating operating rods, each connected at one end to the operating member and at its opposite end to one of the movable contact rods. The operating rods are of substantially equal length and have longitudinal axes that converge and intersect at substantially a common point.

Ultrasound control of magnet growing rod distraction in early onset scoliosis.

PubMed

Pérez Cervera, T; Lirola Criado, J F; Farrington Rueda, D M

2016-01-01

The growing rod technique is currently one of the most common procedures used in the management of early onset scoliosis. However, in order to preserve spine growth and control the deformity it requires frequent surgeries to distract the rods. Magnetically driven growing rods have recently been introduced with same treatment goal, but without the inconvenience of repeated surgical distractions. One of the limitations of this technical advance is an increase in radiation exposure due to the increase in distraction frequency compared to conventional growing rods. An improvement of the original technique is presented, proposing a solution to the inconvenience of multiple radiation exposure using ultrasound technology to control the distraction process of magnetically driven growing rods. Copyright © 2014 SECOT. Publicado por Elsevier España, S.L.U. All rights reserved.

The comet Halley meteoroid stream: just one more model

NASA Astrophysics Data System (ADS)

Ryabova, G. O.

2003-05-01

The present attempt to simulate the formation and evolution of the comet Halley meteoroid stream is based on a tentative physical model of dust ejection of large particles from comet Halley. Model streams consisting of 500-5000 test particles have been constructed according to the following ejection scheme. The particles are ejected from the nucleus along the cometary orbit (r < 9 au) within the sunward 70° cone, and the rate of ejection has been taken as proportional to r-4. Two kinds of spherical particles have been considered: 1 and 0.001 g with density equal to 0.25 g cm-3. Ejections have been simulated for 1404 BC, 141 AD and 837 AD. The equations of motion have been numerically integrated using the Everhart procedure. As a result, a complicated fine structure of the comet Halley meteoroid stream, consisting not of filaments but of layers, has been revealed.

Coaxial stub tuner

NASA Technical Reports Server (NTRS)

Chern, Shy-Shiun (Inventor)

1981-01-01

A coaxial stub tuner assembly is comprised of a short circuit branch diametrically opposite an open circuit branch. The stub of the short circuit branch is tubular, and the stub of the open circuit branch is a rod which extends through the tubular stub into the open circuit branch. The rod is threaded at least at its outer end, and the tubular stub is internally threaded to receive the threads of the rod. The open circuit branch can be easily tuned by turning the threaded rod in the tubular stub to adjust the length of the rod extending into the open circuit branch.

NUCLEAR REACTOR

DOEpatents

Moore, R.V.; Bowen, J.H.; Dent, K.H.

1958-12-01

A heterogeneous, natural uranium fueled, solid moderated, gas cooled reactor is described, in which the fuel elements are in the form of elongated rods and are dlsposed within vertical coolant channels ln the moderator symmetrically arranged as a regular lattice in groups. This reactor employs control rods which operate in vertical channels in the moderator so that each control rod is centered in one of the fuel element groups. The reactor is enclosed in a pressure vessel which ls provided with access holes at the top to facilitate loading and unloadlng of the fuel elements, control rods and control rod driving devices.

CONTROL FOR NEUTRONIC REACTOR

DOEpatents

Lichtenberger, H.V.; Cameron, R.A.

1959-03-31

S>A control rod operating device in a nuclear reactor of the type in which the control rod is gradually withdrawn from the reactor to a position desired during stable operation is described. The apparatus is comprised essentially of a stop member movable in the direction of withdrawal of the control rod, a follower on the control rod engageable with the stop and means urging the follower against the stop in the direction of withdrawal. A means responsive to disengagement of the follower from the stop is provided for actuating the control rod to return to the reactor shut-down position.

Biomechanical stability according to different configurations of screws and rods.

PubMed

Ha, Kee-Yong; Hwang, Sung-Chul; Whang, Tae-Hyuk

2013-05-01

Comparison of biomechanical strength according to 2 different configurations of screws and rods. To compare the biomechanical strength of different configurations of screws and rods composed of the same material and of the same size. Many complications related to instrumentation have been reported. The incidence of metallic failure would differ according to the materials and configurations of the assembly of the screws and rods used. However, to our knowledge, the biomechanical effects of implant assembly rods and screws with different configurations and different contours have not been reported. Biomechanical testing was conducted to compare top tightening (TT) screw-rod configuration with side tightening (ST) screw-rod configuration. All tests were conducted using a hydraulic all-purpose testing machine. All data were acquired at a rate of 10 Hz. Both screw systems used spinal rods of 6 mm diameter and were made of TiAl4V ELI material. Among 5 types of tests, 3 were conducted on the basis of American Society for Testing and Materials (ASTM) F 1798 to 97 and F1717-10. The other 2 tests were conducted for comparing the characteristics between TT and ST pedicle screws according to modified methods from ASTM F 1717-10 and ASTM F 1798-97. All results including axial gripping capacity and yield forces were obtained using the same methods on the basis of the mentioned ASTM standards. In the axial gripping capacity test, the mean axial gripping capacity of the TT screw-rod configuration was 3332 ± 118 N and that of ST was 2222 ± 147 N in straight rods (P = 0.019). In 15-degree contoured rods, TT was 2988 ± 199 N and ST was 2116 ± 423 N (P = 0.014). In 30-degree contoured rods, TT was 2227 ± 408 N and ST was 1814 ± 285 N (P = 0.009). In the pulling-out test, the pulling-out force of ST was 8695 ± 1616 N and that of TT was 6106 ± 195 N (P = 0.014). In the rod-pushing test, the failure force of ST was 4131 ± 205 N and that of TT was 5639 ± 105 N. In the compressive fatigue test, the maximum load was 145 N in ST and 119 N in TT. In the cycle fatigue test, the fatigue strength of ST was higher than that of TT. In the rod-pushing test, the failure force of ST was 4131 ± 205 N and that of TT was 5639 ± 105 N (P=0.046). Two different configurations of rod-screw systems found statistically significant differences with axial gripping, pulling out, and fatigue failures. ST constructs improved fixation stability over TT constructs. It was concluded that ST configuration may reduce complications related to implantation.

Thermal Expansion "Paradox."

ERIC Educational Resources Information Center

Fakhruddin, Hasan

1993-01-01

Describes a paradox in the equation for thermal expansion. If the calculations for heating a rod and subsequently cooling a rod are determined, the new length of the cool rod is shorter than expected. (PR)

Inherited Retinal Degenerative Disease Registry

ClinicalTrials.gov

2017-09-13

Eye Diseases Hereditary; Retinal Disease; Achromatopsia; Bardet-Biedl Syndrome; Bassen-Kornzweig Syndrome; Batten Disease; Best Disease; Choroidal Dystrophy; Choroideremia; Cone Dystrophy; Cone-Rod Dystrophy; Congenital Stationary Night Blindness; Enhanced S-Cone Syndrome; Fundus Albipunctatus; Goldmann-Favre Syndrome; Gyrate Atrophy; Juvenile Macular Degeneration; Kearns-Sayre Syndrome; Leber Congenital Amaurosis; Refsum Syndrome; Retinitis Pigmentosa; Retinitis Punctata Albescens; Retinoschisis; Rod-Cone Dystrophy; Rod Dystrophy; Rod Monochromacy; Stargardt Disease; Usher Syndrome

Pulsed ultrasonic stir welding system

NASA Technical Reports Server (NTRS)

Ding, R. Jeffrey (Inventor)

2013-01-01

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

76 FR 33218 - Carbon and Certain Alloy Steel Wire Rod From Mexico: Initiation of Anti-Circumvention Inquiry of...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-06-08

... Steel Wire Rod From Mexico: Initiation of Anti-Circumvention Inquiry of Antidumping Duty Order AGENCY..., under 19 CFR 351.225(k)(2) to determine whether wire rod with an actual diameter between 4.75 and 5.00 millimeters (mm) is within the scope of the antidumping (AD) order on carbon and certain alloy steel wire rod...

METHOD OF APPLYING METALLIC COATINGS

DOEpatents

Robinson, J.W.; Eubank, L.D.

1961-08-01

A method for applying a protective coating to a uranium rod is described. The steps include preheating the unanium rod to the coating temperature, placement of the rod between two rotating rollers, pouring a coating metal such as aluminum-silicon in molten form between one of the rotating rollers and the uranium rod, and rotating the rollers continually until the coating is built up to the desired thickness. (AEC)

Benchmarking reference services: step by step.

PubMed

Buchanan, H S; Marshall, J G

1996-01-01

This article is a companion to an introductory article on benchmarking published in an earlier issue of Medical Reference Services Quarterly. Librarians interested in benchmarking often ask the following questions: How do I determine what to benchmark; how do I form a benchmarking team; how do I identify benchmarking partners; what's the best way to collect and analyze benchmarking information; and what will I do with the data? Careful planning is a critical success factor of any benchmarking project, and these questions must be answered before embarking on a benchmarking study. This article summarizes the steps necessary to conduct benchmarking research. Relevant examples of each benchmarking step are provided.

Brownian dynamics simulations with stiff finitely extensible nonlinear elastic-Fraenkel springs as approximations to rods in bead-rod models.

PubMed

Hsieh, Chih-Chen; Jain, Semant; Larson, Ronald G

2006-01-28

A very stiff finitely extensible nonlinear elastic (FENE)-Fraenkel spring is proposed to replace the rigid rod in the bead-rod model. This allows the adoption of a fast predictor-corrector method so that large time steps can be taken in Brownian dynamics (BD) simulations without over- or understretching the stiff springs. In contrast to the simple bead-rod model, BD simulations with beads and FENE-Fraenkel (FF) springs yield a random-walk configuration at equilibrium. We compare the simulation results of the free-draining bead-FF-spring model with those for the bead-rod model in relaxation, start-up of uniaxial extensional, and simple shear flows, and find that both methods generate nearly identical results. The computational cost per time step for a free-draining BD simulation with the proposed bead-FF-spring model is about twice as high as the traditional bead-rod model with the midpoint algorithm of Liu [J. Chem. Phys. 90, 5826 (1989)]. Nevertheless, computations with the bead-FF-spring model are as efficient as those with the bead-rod model in extensional flow because the former allows larger time steps. Moreover, the Brownian contribution to the stress for the bead-FF-spring model is isotropic and therefore simplifies the calculation of the polymer stresses. In addition, hydrodynamic interaction can more easily be incorporated into the bead-FF-spring model than into the bead-rod model since the metric force arising from the non-Cartesian coordinates used in bead-rod simulations is absent from bead-spring simulations. Finally, with our newly developed bead-FF-spring model, existing computer codes for the bead-spring models can trivially be converted to ones for effective bead-rod simulations merely by replacing the usual FENE or Cohen spring law with a FENE-Fraenkel law, and this convertibility provides a very convenient way to perform multiscale BD simulations.

Brownian dynamics simulations with stiff finitely extensible nonlinear elastic-Fraenkel springs as approximations to rods in bead-rod models

NASA Astrophysics Data System (ADS)

Hsieh, Chih-Chen; Jain, Semant; Larson, Ronald G.

2006-01-01

A very stiff finitely extensible nonlinear elastic (FENE)-Fraenkel spring is proposed to replace the rigid rod in the bead-rod model. This allows the adoption of a fast predictor-corrector method so that large time steps can be taken in Brownian dynamics (BD) simulations without over- or understretching the stiff springs. In contrast to the simple bead-rod model, BD simulations with beads and FENE-Fraenkel (FF) springs yield a random-walk configuration at equilibrium. We compare the simulation results of the free-draining bead-FF-spring model with those for the bead-rod model in relaxation, start-up of uniaxial extensional, and simple shear flows, and find that both methods generate nearly identical results. The computational cost per time step for a free-draining BD simulation with the proposed bead-FF-spring model is about twice as high as the traditional bead-rod model with the midpoint algorithm of Liu [J. Chem. Phys. 90, 5826 (1989)]. Nevertheless, computations with the bead-FF-spring model are as efficient as those with the bead-rod model in extensional flow because the former allows larger time steps. Moreover, the Brownian contribution to the stress for the bead-FF-spring model is isotropic and therefore simplifies the calculation of the polymer stresses. In addition, hydrodynamic interaction can more easily be incorporated into the bead-FF-spring model than into the bead-rod model since the metric force arising from the non-Cartesian coordinates used in bead-rod simulations is absent from bead-spring simulations. Finally, with our newly developed bead-FF-spring model, existing computer codes for the bead-spring models can trivially be converted to ones for effective bead-rod simulations merely by replacing the usual FENE or Cohen spring law with a FENE-Fraenkel law, and this convertibility provides a very convenient way to perform multiscale BD simulations.

Fighter Pilot Ejection Study as an Educational Tool

ERIC Educational Resources Information Center

Robinson, Garry; Jovanoski, Zlatko

2010-01-01

In this article, we apply the well-known equations of projectile motion to the case of a fighter pilot ejecting from an aircraft, the aim being to establish under what conditions there is danger of impact with the rear vertical stabilizer. The drag force on the pilot after ejection is assumed to vary as the velocity squared and the aircraft motion…

Survivability Modeling & Simulation(Aircraft Survivability, Fall 2009)

DTIC Science & Technology

2009-01-01

Projects.” The Human Effectiveness Directorate is responsible for providing injury assessments for most modern Air Force ejection systems, for...developing ejection test mannequins, and for continuing to define human injury limits and criteria. The directorate maintains a man-rated horizontal...Using numerous models and testing, the directorate can define ejection /impact injury criteria for aircraft equipment to prevent personnel injuries

Evidence that magnetic energy shedding in solar filament eruptions is the drive in accompanying flares and coronal mass ejections

NASA Technical Reports Server (NTRS)

Moore, Ronald L.

1988-01-01

The dependence of the magnetic energy on the field expansion and untwisting of the flux tube in which an erupting solar filament is embedded has been determined in order to evaluate the energy decrease in the erupting flux tube. Magnetic energy shedding by the filament-field eruption is found to be the driving mechanism in both filament-eruption flares and coronal mass ejections. Confined filament-eruption flares, filament-eruption flares with sprays and coronal mass ejections, and coronal mass ejections from quiescent filament eruptions are all shown to be similar types of events.

Diastolic dysfunction and heart failure with a preserved ejection fraction: Relevance in critical illness and anaesthesia

PubMed Central

Maharaj, R.

2012-01-01

Epidemiological and clinical studies suggest that HF with a preserved ejection fraction will become the more common form of HF which clinicians will encounter. The spectrum of diastolic disease extends from the asymptomatic phase to fulminant cardiac failure. These patients are commonly encountered in operating rooms and critical care units. A clearer understanding of the underlying pathophysiology and clinical implications of HF with a preserved ejection fraction is fundamental to directing further research and to evaluate interventions. This review highlights the impact of diastolic dysfunction and HF with a preserved ejection fraction during the perioperative period and during critical illness. PMID:23960679

On the Physics of Fizziness: How liquid properties control bursting bubble aerosol production?

NASA Astrophysics Data System (ADS)

Ghabache, Elisabeth; Antkowiak, Arnaud; Josserand, Christophe; Seon, Thomas

2014-11-01

Either in a champagne glass or at the oceanic scales, the tiny capillary bubbles rising at the surface burst in ejecting myriads of droplets. Focusing on the ejected droplets produced by a single bubble, we investigate experimentally how liquid properties and bubble size affect their characteristics: number, ejection velocities, sizes and ejection heights. These results allow us to finely tune the bursting bubble aerosol production. In the context of champagne industry, aerosols play a major role by spreading wine aroma above the glass. We demonstrate that this champagne fizz can be enhanced by selecting the wine viscosity and the bubble size, thanks to specially designed glass.

Experimental comparison of forces resisting viral DNA packaging and driving DNA ejection

NASA Astrophysics Data System (ADS)

Keller, Nicholas; Berndsen, Zachary T.; Jardine, Paul J.; Smith, Douglas E.

2017-05-01

We compare forces resisting DNA packaging and forces driving DNA ejection in bacteriophage phi29 with theoretical predictions. Ejection of DNA from prohead-motor complexes is triggered by heating complexes after in vitro packaging and force is inferred from the suppression of ejection by applied osmotic pressure. Ejection force from 0 % to 80 % filling is found to be in quantitative agreement with predictions of a continuum mechanics model that assumes a repulsive DNA-DNA interaction potential based on DNA condensation studies and predicts an inverse-spool conformation. Force resisting DNA packaging from ˜80 % to 100 % filling inferred from optical tweezers studies is also consistent with the predictions of this model. The striking agreement with these two different measurements suggests that the overall energetics of DNA packaging is well described by the model. However, since electron microscopy studies of phi29 do not reveal a spool conformation, our findings suggest that the spool model overestimates the role of bending rigidity and underestimates the role of intrastrand repulsion. Below ˜80 % filling the inferred forces resisting packaging are unexpectedly lower than the inferred ejection forces, suggesting that in this filling range the forces are less accurately determined or strongly temperature dependent.

Right ventricular function after coronary artery bypass graft surgery--a magnetic resonance imaging study.

PubMed

Joshi, Subodh B; Roswell, Robert O; Salah, Ali K; Zeman, Peter R; Corso, Paul J; Lindsay, Joseph; Fuisz, Anthon R

2010-01-01

A reduction in right ventricular function commonly occurs in the early postoperative period after coronary artery bypass graft surgery (CABG). We sought to determine the longer-term effect of CABG on right ventricular function. Cardiac magnetic resonance imaging was performed before and approximately 3 months after surgery in 28 patients undergoing elective CABG. Right ventricular (RV) ejection fraction was assessed by planimetry of electrocardiographically gated cine images. There was a statistically significant increase in left ventricular ejection fraction from 50% to 58% (P=.003) after CABG. RV ejection fraction also increased from 54% to 60% (P=.002). In patients with lower baseline RV ejection fraction (below the median, < 53%), this parameter improved from 47% to 57% (P<.001). Both on-pump (47% vs. 62%, P=.003) as well as off-pump CABG (47% vs. 55%, P=.009) lead to an improvement in RV function in patients in the initial low RV ejection fraction group. Long-term right ventricular function was not adversely affected by CABG. An improvement in RV function occurred after surgery in patients with low baseline RV ejection fraction and was similar in patients who underwent surgery with or without cardiopulmonary bypass.

Dimensional correlates of left ventricular dilation in the presence of hypertrophy.

PubMed

Al-Nouri, M B; Ford, L E; Wix, H

1983-01-01

Twelve normal subjects, 50 patients with valvular heart disease, and 14 with hypertension were studied. Those with valvular disease were divided into two groups: 28 with angiographically measured ejection fractions greater than or equal to 0.6 and 22 with ejection fractions less than 0.6. The echocardiographically measured ventricular thickness divided by radius ratio (t/r) was approximately proportional to peak systolic pressure (P) in all groups having ejection fractions greater than or equal to 0.6, so that the t/r divided by P ratios were nearly the same. Patients with ejection fractions less than 0.6 had significantly lower t/r divided by P values. No single component of the t/r divided by P ratio would identify the patients with lower ejection fractions. The t/r divided by P ratios in 14 hypertensive patients were nearly identical to the ratios in six patients with aortic stenosis and ejection fractions greater than or equal to 0.6, indicating that an aortic valve gradient does not cause a grossly abnormal form of pressure hypertrophy. The t/r ratio is thus a double sensitive, noninvasive index of dilation when correlated with systolic pressure.

Two-Stage Dynamics of In Vivo Bacteriophage Genome Ejection

NASA Astrophysics Data System (ADS)

Chen, Yi-Ju; Wu, David; Gelbart, William; Knobler, Charles M.; Phillips, Rob; Kegel, Willem K.

2018-04-01

Biopolymer translocation is a key step in viral infection processes. The transfer of information-encoding genomes allows viruses to reprogram the cell fate of their hosts. Constituting 96% of all known bacterial viruses [A. Fokine and M. G. Rossmann, Molecular architecture of tailed double-stranded DNA phages, Bacteriophage 4, e28281 (2014)], the tailed bacteriophages deliver their DNA into host cells via an "ejection" process, leaving their protein shells outside of the bacteria; a similar scenario occurs for mammalian viruses like herpes, where the DNA genome is ejected into the nucleus of host cells, while the viral capsid remains bound outside to a nuclear-pore complex. In light of previous experimental measurements of in vivo bacteriophage λ ejection, we analyze here the physical processes that give rise to the observed dynamics. We propose that, after an initial phase driven by self-repulsion of DNA in the capsid, the ejection is driven by anomalous diffusion of phage DNA in the crowded bacterial cytoplasm. We expect that this two-step mechanism is general for phages that operate by pressure-driven ejection, and we discuss predictions of our theory to be tested in future experiments.

Energetics of genome ejection from phage revealed by isothermal titration calorimetry

NASA Astrophysics Data System (ADS)

Jeembaeva, Meerim; Jonsson, Bengt; Castelnovo, Martin; Evilevitch, Alex

2009-03-01

It has been experimentally shown that ejection of double-stranded DNA from phage is driven by internal pressure reaching tens of atmospheres. This internal pressure is partially responsible for delivery of DNA into the host cell. While several theoretical models and simulations nicely describe the experimental data of internal forces either resisting active packaging or equivalently favoring spontaneous ejection, there are no direct energy measurements available that would help to verify how quantitative these theories are. We performed direct measurements of the enthalpy responsible for DNA ejection from phage λ, using Isothermal Titration Calorimetry. The phage capsids were ``opened'' in vitro by titrating λ into a solution with LamB receptor and the enthalpy of DNA ejection process was measured. In his way, enthalpy stored in λ was determined as a function of packaged DNA length comparing wild-type phage λ (48.5 kb) with a shorter λ-DNA length mutant (37.7 kb). The temperature dependence of the ejection enthalpy was also investigated. The values obtained were in good agreement with existing models and provide a better understanding of ds- DNA packaging and release mechanisms in motor-packaged viruses (e.g., tailed bacteriophages, Herpes Simplex, and adenoviruses).

Experimental comparison of forces resisting viral DNA packaging and driving DNA ejection.

PubMed

Keller, Nicholas; Berndsen, Zachary T; Jardine, Paul J; Smith, Douglas E

2017-05-01

We compare forces resisting DNA packaging and forces driving DNA ejection in bacteriophage phi29 with theoretical predictions. Ejection of DNA from prohead-motor complexes is triggered by heating complexes after in vitro packaging and force is inferred from the suppression of ejection by applied osmotic pressure. Ejection force from 0% to 80% filling is found to be in quantitative agreement with predictions of a continuum mechanics model that assumes a repulsive DNA-DNA interaction potential based on DNA condensation studies and predicts an inverse-spool conformation. Force resisting DNA packaging from ∼80% to 100% filling inferred from optical tweezers studies is also consistent with the predictions of this model. The striking agreement with these two different measurements suggests that the overall energetics of DNA packaging is well described by the model. However, since electron microscopy studies of phi29 do not reveal a spool conformation, our findings suggest that the spool model overestimates the role of bending rigidity and underestimates the role of intrastrand repulsion. Below ∼80% filling the inferred forces resisting packaging are unexpectedly lower than the inferred ejection forces, suggesting that in this filling range the forces are less accurately determined or strongly temperature dependent.

Signaling States of Rhodopsin in Rod Disk Membranes Lacking Transducin βγ-Complex

PubMed Central

Lomonosova, Elena; Kolesnikov, Alexander V.; Kefalov, Vladimir J.

2012-01-01

Purpose. To characterize the possible role of transducin Gtβγ-complex in modulating the signaling properties of photoactivated rhodopsin and its lifetime in rod disc membranes and intact rods. Methods. Rhodopsin photolysis was studied using UV-visible spectroscopy and rapid scanning spectroscopy in the presence of hydroxylamine in highly purified wild-type and Gtγ-deficient mouse rod disc membranes. Complex formation between photoactivated rhodopsin and transducin was measured by extra-metarhodopsin (meta) II assay. Recovery of dark current and flash sensitivity in individual intact wild-type and Gtγ-deficient mouse rods was measured by single-cell suction recordings. Results. Photoconversion of rhodopsin to meta I/meta II equilibrium proceeds normally after elimination of the Gtβγ-complex. The meta I/meta II ratio, the rate of meta II decay, the reactivity of meta II toward hydroxylamine, and the rate of meta III formation in Gtγ-deficient rod disc membranes were identical with those observed in wild-type samples. Under low-intensity illumination, the amount of extra–meta II in Gtγ-deficient discs was significantly reduced. The initial rate of dark current recovery after 12% rhodopsin bleach was three times faster in Gtγ-deficient rods, whereas the rate of the late current recovery was largely unchanged. Mutant rods also exhibited faster postbleach recovery of flash sensitivity. Conclusions. Photoactivation and thermal decay of rhodopsin proceed similarly in wild-type and Gtγ-deficient mouse rods, but the complex formation between photoactivated rhodopsin and transducin is severely compromised in the absence of Gtβγ. The resultant lower transduction activation contributes to faster photoresponse recovery after a moderate pigment bleach in Gtγ-deficient rods. PMID:22266510

Variation in Rhodopsin Kinase Expression Alters the Dim Flash Response Shut Off and the Light Adaptation in Rod Photoreceptors

PubMed Central

Sakurai, Keisuke; Young, Joyce E.; Kefalov, Vladimir J.; Khani, Shahrokh C.

2011-01-01

Purpose. Rod photoreceptors are exquisitely sensitive light detectors that function in dim light. The timely inactivation of their light responses is critical for the ability of rods to reliably detect and count photons. A key step in the inactivation of the rod transduction is the phosphorylation of the rod visual pigment, rhodopsin, catalyzed by G-protein-dependent receptor kinase 1 (GRK1). Absence of GRK1 greatly prolongs the photoreceptors' light response and enhances their susceptibility to degeneration. This study examined the light responses from mouse rods expressing various levels of GRK1 to evaluate how their function is modulated by rhodopsin inactivation. Methods. Transretinal and single-cell rod electrophysiological recordings were obtained from several strains of mice expressing GRK1 at 0.3- to 3-fold the wild-type levels. The effect of GRK1 expression level on the function of mouse rods was examined in darkness and during background adaptation. Results. Altering the expression of GRK1 from 0.3- to 3-fold that in wild-type rods had little effect on the single photon response amplitude. Notably, increasing the expression level of GRK1 accelerated the dim flash response shut off but had no effect on the saturated response shut off. Additionally, GRK1 excess abolished the acceleration of saturated responses shut off during light adaptation. Conclusions. These results demonstrate that rhodopsin inactivation can modulate the kinetics of recovery from dim light stimulation. More importantly, the ratio of rhodopsin kinase to its modulator recoverin appears critical for the proper adaptation of rods and the acceleration of their response shut off in background light. PMID:21474765

A biomechanical investigation of dual growing rods used for fusionless scoliosis correction.

PubMed

Quick, M E; Grant, C A; Adam, C J; Askin, G N; Labrom, R D; Pearcy, M J

2015-01-01

The use of dual growing rods is a fusionless surgical approach to the treatment of early onset scoliosis which aims to harness potential growth and correct spinal deformity. The purpose of this study was to compare the in-vitro biomechanical response of two different dual rod designs under axial rotation loading. Six porcine spines were dissected into seven level thoracolumbar multi-segment units. Each specimen was mounted and tested in a biaxial Instron machine, undergoing nondestructive left and right axial rotation to peak moments of 4 Nm at a constant rotation rate of 8 deg. s(-1). A motion tracking system (Optotrak) measured 3D displacements of individual vertebrae. Each spine was tested in an un-instrumented state first and then with appropriately sized semi-constrained and 'rigid' growing rods in alternating sequence. The range of motion, neutral zone size and stiffness were calculated from the moment-rotation curves and intervertebral range of motion was calculated from Optotrak data. Irrespective of test sequence, rigid rods showed a significant reduction of total rotation across all instrumented levels (with increased stiffness) whilst semi-constrained rods exhibited similar rotational behavior to the un-instrumented spines (P<0.05). An 11.1% and 8.0% increase in stiffness for left and right axial rotation respectively and 14.9% reduction in total range of motion were recorded with dual rigid rods compared with semi-constrained rods. Based on these findings, the Semi-constrained growing rods were shown to not increase axial rotation stiffness compared with un-instrumented spines. This is thought to provide a more physiological environment for the growing spine compared to dual rigid rod constructs. Copyright © 2014 Elsevier Ltd. All rights reserved.

In vivo optophysiology reveals that G-protein activation triggers osmotic swelling and increased light scattering of rod photoreceptors

PubMed Central

Nguyen, Phuong T.; Yarov-Yarovoy, Vladimir; Burns, Marie E.; Pugh, Edward N.

2017-01-01

The light responses of rod and cone photoreceptors have been studied electrophysiologically for decades, largely with ex vivo approaches that disrupt the photoreceptors’ subretinal microenvironment. Here we report the use of optical coherence tomography (OCT) to measure light-driven signals of rod photoreceptors in vivo. Visible light stimulation over a 200-fold intensity range caused correlated rod outer segment (OS) elongation and increased light scattering in wild-type mice, but not in mice lacking the rod G-protein alpha subunit, transducin (Gαt), revealing these responses to be triggered by phototransduction. For stimuli that photoactivated one rhodopsin per Gαt the rod OS swelling response reached a saturated elongation of 10.0 ± 2.1%, at a maximum rate of 0.11% s−1. Analyzing swelling as osmotically driven water influx, we find the H2O membrane permeability of the rod OS to be (2.6 ± 0.4) × 10−5 cm⋅s−1, comparable to that of other cells lacking aquaporin expression. Application of Van’t Hoff’s law reveals that complete activation of phototransduction generates a potentially harmful 20% increase in OS osmotic pressure. The increased backscattering from the base of the OS is explained by a model combining cytoplasmic swelling, translocation of dissociated G-protein subunits from the disc membranes into the cytoplasm, and a relatively higher H2O permeability of nascent discs in the basal rod OS. Translocation of phototransduction components out of the OS may protect rods from osmotic stress, which could be especially harmful in disease conditions that affect rod OS structural integrity. PMID:28320964

CNGA3 Deficiency Affects Cone Synaptic Terminal Structure and Function and Leads to Secondary Rod Dysfunction and Degeneration

PubMed Central

Xu, Jianhua; Morris, Lynsie M.; Michalakis, Stylianos; Biel, Martin; Fliesler, Steven J.; Sherry, David M.

2012-01-01

Purpose. To investigate rod function and survival after cone dysfunction and degeneration in a mouse model of cone cyclic nucleotide-gated (CNG) channel deficiency. Methods. Rod function and survival in mice with cone CNG channel subunit CNGA3 deficiency (CNGA3−/− mice) were evaluated by electroretinographic (ERG), morphometric, and Western blot analyses. The arrangement, integrity, and ultrastructure of photoreceptor terminals were investigated by immunohistochemistry and electron microscopy. Results. The authors found loss of cone function and cone death accompanied by impairment of rods and rod-driven signaling in CNGA3−/− mice. Scotopic ERG b-wave amplitudes were reduced by 15% at 1 month, 30% at 6 months, and 40% at 9 months and older, while scotopic a-wave amplitudes were decreased by 20% at 9 months, compared with ERGs of age-matched wild-type mice. Outer nuclear layer thickness in CNGA3−/− retina was reduced by 15% at 12 months compared with age-matched wild-type controls. This was accompanied by a 30%–40% reduction in expression of rod-specific proteins, including rhodopsin, rod transducin α-subunit, and glutamic acid-rich protein (GARP). Cone terminals in the CNGA3−/− retina showed a progressive loss of neurochemical and ultrastructural integrity. Abnormalities were observed as early as 1 month. Disorganized rod terminal ultrastructure was noted by 12 months. Conclusions. These findings demonstrate secondary rod impairment and degeneration after cone degeneration in mice with cone CNG channel deficiency. Loss of cone phototransduction accompanies the compromised integrity of cone terminals. With time, rod synaptic structure, function, and viability also become compromised. PMID:22247469

Weak endogenous Ca2+ buffering supports sustained synaptic transmission by distinct mechanisms in rod and cone photoreceptors in salamander retina

PubMed Central

Van Hook, Matthew J; Thoreson, Wallace B

2015-01-01

Differences in synaptic transmission between rod and cone photoreceptors contribute to different response kinetics in rod- versus cone-dominated visual pathways. We examined Ca2+ dynamics in synaptic terminals of tiger salamander photoreceptors under conditions that mimicked endogenous buffering to determine the influence on kinetically and mechanistically distinct components of synaptic transmission. Measurements of ICl(Ca) confirmed that endogenous Ca2+ buffering is equivalent to ˜0.05 mmol/L EGTA in rod and cone terminals. Confocal imaging showed that with such buffering, depolarization stimulated large, spatially unconstrained [Ca2+] increases that spread throughout photoreceptor terminals. We calculated immediately releasable pool (IRP) size and release efficiency in rods by deconvolving excitatory postsynaptic currents and presynaptic Ca2+ currents. Peak efficiency of ˜0.2 vesicles/channel was similar to that of cones (˜0.3 vesicles/channel). Efficiency in both cell types was not significantly affected by using weak endogenous Ca2+ buffering. However, weak Ca2+ buffering speeded Ca2+/calmodulin (CaM)-dependent replenishment of vesicles to ribbons in both rods and cones, thereby enhancing sustained release. In rods, weak Ca2+ buffering also amplified sustained release by enhancing CICR and CICR-stimulated release of vesicles at nonribbon sites. By contrast, elevating [Ca2+] at nonribbon sites in cones with weak Ca2+ buffering and by inhibiting Ca2+ extrusion did not trigger additional release, consistent with the notion that exocytosis from cones occurs exclusively at ribbons. The presence of weak endogenous Ca2+ buffering in rods and cones facilitates slow, sustained exocytosis by enhancing Ca2+/CaM-dependent replenishment of ribbons in both rods and cones and by stimulating nonribbon release triggered by CICR in rods. PMID:26416977

Variation in rhodopsin kinase expression alters the dim flash response shut off and the light adaptation in rod photoreceptors.

PubMed

Sakurai, Keisuke; Young, Joyce E; Kefalov, Vladimir J; Khani, Shahrokh C

2011-08-29

Rod photoreceptors are exquisitely sensitive light detectors that function in dim light. The timely inactivation of their light responses is critical for the ability of rods to reliably detect and count photons. A key step in the inactivation of the rod transduction is the phosphorylation of the rod visual pigment, rhodopsin, catalyzed by G-protein-dependent receptor kinase 1 (GRK1). Absence of GRK1 greatly prolongs the photoreceptors' light response and enhances their susceptibility to degeneration. This study examined the light responses from mouse rods expressing various levels of GRK1 to evaluate how their function is modulated by rhodopsin inactivation. Transretinal and single-cell rod electrophysiological recordings were obtained from several strains of mice expressing GRK1 at 0.3- to 3-fold the wild-type levels. The effect of GRK1 expression level on the function of mouse rods was examined in darkness and during background adaptation. Altering the expression of GRK1 from 0.3- to 3-fold that in wild-type rods had little effect on the single photon response amplitude. Notably, increasing the expression level of GRK1 accelerated the dim flash response shut off but had no effect on the saturated response shut off. Additionally, GRK1 excess abolished the acceleration of saturated responses shut off during light adaptation. These results demonstrate that rhodopsin inactivation can modulate the kinetics of recovery from dim light stimulation. More importantly, the ratio of rhodopsin kinase to its modulator recoverin appears critical for the proper adaptation of rods and the acceleration of their response shut off in background light.

A novel positive allosteric modulator of the GABAA receptor: the action of (+)-ROD188

PubMed Central

Thomet, Urs; Baur, Roland; Razet, Rodolphe; Dodd, Robert H; Furtmüller, Roman; Sieghart, Werner; Sigel, Erwin

2000-01-01

(+)-ROD188 was synthesized in the search for novel ligands of the GABA binding site. It shares some structural similarity with bicuculline. (+)-ROD188 failed to displace [3H]-muscimol in binding studies and failed to induce channel opening in recombinant rat α1β2γ2 GABAA receptors functionally expressed in Xenopus oocytes. (+)-ROD188 allosterically stimulated GABA induced currents. Displacement of [3H]-Ro15-1788 indicated a low affinity action at the benzodiazepine binding site. In functional studies, stimulation by (+)-ROD188 was little sensitive to the presence of 1 μM of the benzodiazepine antagonist Ro 15-1788, and (+)-ROD188 also stimulated currents mediated by α1β2, indicating a major mechanism of action different from that of benzodiazepines. Allosteric stimulation by (+)-ROD188 was similar in α1β2N265S as in unmutated α1β2, while that by loreclezole was strongly reduced. (+)-ROD188 also strongly stimulated currents elicited by either pentobarbital or 5α-pregnan-3α-ol-20-one (3α-OH-DHP), in line with a mode of action different from that of barbiturates or neurosteroids as channel agonists. Stimulation by (+)-ROD188 was largest in α6β2γ2 (α6β2γ2>>α1β2γ2=α5β2γ2>α2β2γ2= α3β2γ2), indicating a unique subunit isoform specificity. Miniature inhibitory postsynaptic currents (mIPSC) in cultures of rat hippocampal neurons, caused by spontaneous release of GABA showed a prolonged decay time in the presence of 30 μM (+)-ROD188, indicating an enhanced synaptic inhibitory transmission. PMID:11030736

Study on Sumbawa gold ore liberation using rod mill: effect of rod-number and rotational speed on particle size distribution

NASA Astrophysics Data System (ADS)

Prasetya, A.; Mawadati, A.; Putri, A. M. R.; Petrus, H. T. B. M.

2018-01-01

Comminution is one of crucial steps in gold ore processing used to liberate the valuable minerals from gaunge mineral. This research is done to find the particle size distribution of gold ore after it has been treated through the comminution process in a rod mill with various number of rod and rotational speed that will results in one optimum milling condition. For the initial step, Sumbawa gold ore was crushed and then sieved to pass the 2.5 mesh and retained on the 5 mesh (this condition was taken to mimic real application in artisanal gold mining). Inserting the prepared sample into the rod mill, the observation on effect of rod-number and rotational speed was then conducted by variating the rod number of 7 and 10 while the rotational speed was varied from 60, 85, and 110 rpm. In order to be able to provide estimation on particle distribution of every condition, the comminution kinetic was applied by taking sample at 15, 30, 60, and 120 minutes for size distribution analysis. The change of particle distribution of top and bottom product as time series was then treated using Rosin-Rammler distribution equation. The result shows that the homogenity of particle size and particle size distribution is affected by rod-number and rotational speed. The particle size distribution is more homogeneous by increasing of milling time, regardless of rod-number and rotational speed. Mean size of particles do not change significantly after 60 minutes milling time. Experimental results showed that the optimum condition was achieved at rotational speed of 85 rpm, using rod-number of 7.

RodZ and PgsA Play Intertwined Roles in Membrane Homeostasis of Bacillus subtilis and Resistance to Weak Organic Acid Stress

PubMed Central

van Beilen, Johan; Blohmke, Christoph J.; Folkerts, Hendrik; de Boer, Richard; Zakrzewska, Anna; Kulik, Wim; Vaz, Fred M.; Brul, Stanley; Ter Beek, Alexander

2016-01-01

Weak organic acids like sorbic and acetic acid are widely used to prevent growth of spoilage organisms such as Bacilli. To identify genes involved in weak acid stress tolerance we screened a transposon mutant library of Bacillus subtilis for sorbic acid sensitivity. Mutants of the rodZ (ymfM) gene were found to be hypersensitive to the lipophilic weak organic acid. RodZ is involved in determining the cell’s rod-shape and believed to interact with the bacterial actin-like MreB cytoskeleton. Since rodZ lies upstream in the genome of the essential gene pgsA (phosphatidylglycerol phosphate synthase) we hypothesized that expression of the latter might also be affected in rodZ mutants and hence contribute to the phenotype observed. We show that both genes are co-transcribed and that both the rodZ::mini-Tn10 mutant and a conditional pgsA mutant, under conditions of minimal pgsA expression, were sensitive to sorbic and acetic acid. Both strains displayed a severely altered membrane composition. Compared to the wild-type strain, phosphatidylglycerol and cardiolipin levels were lowered and the average acyl chain length was elongated. Induction of rodZ expression from a plasmid in our transposon mutant led to no recovery of weak acid susceptibility comparable to wild-type levels. However, pgsA overexpression in the same mutant partly restored sorbic acid susceptibility and fully restored acetic acid sensitivity. A construct containing both rodZ and pgsA as on the genome led to some restored growth as well. We propose that RodZ and PgsA play intertwined roles in membrane homeostasis and tolerance to weak organic acid stress. PMID:27818647

Macrosegregation During Re-melting and Holding of Directionally Solidified Al-7 wt.% Si Alloy in Microgravity

NASA Astrophysics Data System (ADS)

Lauer, M.; Ghods, M.; Angart, S. G.; Grugel, R. N.; Tewari, S. N.; Poirier, D. R.

2017-08-01

As-cast aluminum-7 wt.% ailicon alloy sample rods were re-melted and directionally solidified on Earth which resulted in uniform dendritically aligned arrays. These arrays were then partially back-melted through an imposed, and constant, temperature gradient in the microgravity environment aboard the International Space Station. The mushy zones that developed in the seed crystals were held for different periods prior to initiating directional solidification. Upon return, examination of the initial mushy-zone regions exhibited significant macrosegregation in terms of a solute-depleted zone that increased as a function of the holding time. The silicon (solute) content in these regions was measured on prepared longitudinal sections by electron microprobe analysis as well as by determining the fraction eutectic on several transverse sections. The silicon content was found to increase up the temperature gradient resulting in significant silicon concentration immediately ahead of the mushy-zone tips. The measured macrosegregation agrees well with calculations from a mathematical model developed to simulate the re-melting and holding process. The results, due to processing in a microgravity environment where buoyancy and thermosolutal convection are minimized, serve as benchmark solidification data.

NEUTRONIC REACTORS

DOEpatents

Wigner, E.P.; Young, G.J.

1958-10-14

A method is presented for loading and unloading rod type fuel elements of a neutronic reactor of the heterogeneous, solld moderator, liquid cooled type. In the embodiment illustrated, the fuel rods are disposed in vertical coolant channels in the reactor core. The fuel rods are loaded and unloaded through the upper openings of the channels which are immersed in the coolant liquid, such as water. Unloading is accomplished by means of a coffer dam assembly having an outer sleeve which is placed in sealing relation around the upper opening. A radiation shield sleeve is disposed in and reciprocable through the coffer dam sleeve. A fuel rod engaging member operates through the axial bore in the radiation shield sleeve to withdraw the fuel rod from its position in the reactor coolant channel into the shield, the shield snd rod then being removed. Loading is accomplished in the reverse procedure.

Methodology of the Westinghouse dynamic rod worth measurement technique

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

Chao, Y.A.; Chapman, D.M.; Easter, M.E.

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 processmore » 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.« less

Domain and network aggregation of CdTe quantum rods within Langmuir Blodgett monolayers

NASA Astrophysics Data System (ADS)

Zimnitsky, Dmitry; Xu, Jun; Lin, Zhiqun; Tsukruk, Vladimir V.

2008-05-01

Control over the organization of quantum rods was demonstrated by changing the surface area at the air-liquid interface by means of the Langmuir-Blodgett (LB) technique. The LB isotherm of CdTe quantum rods capped with a mixture of alkylphosphines shows a transition point in the liquid-solid state, which is caused by the inter-rod reorganization. As we observed, at low surface pressure the quantum rods are assembled into round-shaped aggregates composed of a monolayer of nanorods packed in limited-size clusters with random orientation. The increase of the surface pressure leads to the rearrangement of these aggregates into elongated bundles composed of uniformly oriented nanorod clusters. Further compression results in denser packing of nanorods aggregates and in the transformation of monolayered domains into a continuous network of locally ordered quantum rods.

Light Water Breeder Reactor fuel rod design and performance characteristics (LWBR Development Program)

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

Campbell, W.R.; Giovengo, J.F.

1987-10-01

Light Water Breeder Reactor (LWBR) fuel rods were designed to provide a reliable fuel system utilizing thorium/uranium-233 mixed-oxide fuel while simultaneously minimizing structural material to enhance fuel breeding. The fuel system was designed to be capable of operating successfully under both load follow and base load conditions. The breeding objective required thin-walled, low hafnium content Zircaloy cladding, tightly spaced fuel rods with a minimum number of support grid levels, and movable fuel rod bundles to supplant control rods. Specific fuel rod design considerations and their effects on performance capability are described. Successful completion of power operations to over 160 percentmore » of design lifetime including over 200 daily load follow cycles has proven the performance capability of the fuel system. 68 refs., 19 figs., 44 tabs.« less

Intraoperative pulmonary embolism of Harrington rod during spinal surgery: the potential dangers of rod cutting.

PubMed

Aylott, Caspar E W; Hassan, Kamran; McNally, Donal; Webb, John K

2006-12-01

This is a case report and laboratory-based biomechanics study. The objective is to report the first case of Titanium rod embolisation during scoliosis surgery into the Pulmonary artery. To investigate the potential of an unconstrained cut Titanium rod fragment to cause wounding with reference to recognised weapons. Embolisation of a foreign body to the heart is rare. Bullet embolisation to the heart and lungs is infrequently reported in the last 80 years. Iatrogenic cases of foreign body embolisation are very rare. Fifty 1-2 cm segments of Titanium rod were cut in an unconstrained manner and a novel method was used to calculate velocity. A high-speed camera (6,000 frames/s) was used to further measure velocity and study projectile motion. The wounding potential was investigated using lambs liver, high-speed photography and local dissection. Rod velocities were measured in excess of 23 m s(-1). Rods were seen to tumble end-over-end with a maximum speed of 560 revolutions/s. The maximum kinetic energy was 0.61 J which is approximately 2% that of a crossbow. This is sufficient to cause significant liver damage. The degree of surface damage and internal disruption was influenced by the orientation of the rod fragment at impact. An unconstrained cut segment of a Titanium rod has a significant potential to wound. Precautions should be taken to avoid this potentially disastrous but preventable complication.

Skin bridge versus rod colostomy in children - comparison between complications.

PubMed

Askarpour, Shahnam; Peyvasteh, Mehran; Changai, Bahram; Javaherizadeh, Hazhir

2012-10-01

Due to economic problems, sigmoid loop colostomy using glass rod may cause problems for our patients for finding glass rod and several visits. The aim of the study was to compare rod versus skin bridge colostomy. In this study, 42 cases who are candidate for colostomy were included. Cases were randomly placed in skin bridge and rod colostomy group. Independent sample t-test and Chi-square were used for comparison. SPSS version 16.0 (SPSS Inc, Chicago, IL, USA) was used for analysis. Of 42 cases, 20 were male and 22 were female. Hirschsprung's disease was the indication of colostomy in 33 cases. In nine cases, imperforate anus was the indication of colostomy. Mean time of surgery was 79.4 and 82.5 minute for the rod and skin bridge group respectively (P>0.05). Retraction was seen in 2 case of rod group, and no case of skin bridge group. Prolapse was seen in 2 (9.5%) case of rod group and 1(4.7%) case in skin bridge. There were no reports of necrosis, stenosis, and hernia in both groups. In the skin bridge group the rates of complications were lower but the groups are too small for statistical analysis. Colostomy with a skin bridge method may decrease number of revision and expenses and may be appropriate option. Sigmoid loop colostomy using skin bridge flap may be appropriate choice in developing country. Another study with more samples is recommended to better comparison of Skin Bridge versus rod colostomy.

Directionally Interacting Spheres and Rods Form Ordered Phases

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

Liu, Wenyan; Mahynski, Nathan A.; Gang, Oleg

The structures formed by mixtures of dissimilarly shaped nanoscale objects can significantly enhance our ability to produce nanoscale architectures. However, understanding their formation is a complex problem due to the interplay of geometric effects (entropy) and energetic interactions at the nanoscale. Spheres and rods are perhaps the most basic geometrical shapes and serve as convenient models of such dissimilar objects. The ordered phases formed by each of these individual shapes have already been explored, but, when mixed, spheres and rods have demonstrated only limited structural organization to date. We show using experiments and theory that the introduction of directional attractionsmore » between rod ends and isotropically interacting spherical nanoparticles (NPs) through DNA base pairing leads to the formation of ordered three-dimensional lattices. The spheres and rods arrange themselves in a complex alternating manner, where the spheres can form either a face-centered cubic (FCC) or hexagonal close-packed (HCP) lattice, or a disordered phase, as observed by in situ X-ray scattering. Increasing NP diameter at fixed rod length yields an initial transition from a disordered phase to the HCP crystal, energetically stabilized by rod-rod attraction across alternating crystal layers, as revealed by theory. In the limit of large NPs, the FCC structure is instead stabilized over the HCP by rod entropy. Thus, we propose that directionally specific attractions in mixtures of anisotropic and isotropic objects offer insight into unexplored self-assembly behavior of noncomplementary shaped particles.« less

Directionally Interacting Spheres and Rods Form Ordered Phases

DOE PAGES

Liu, Wenyan; Mahynski, Nathan A.; Gang, Oleg; ...

2017-05-10

The structures formed by mixtures of dissimilarly shaped nanoscale objects can significantly enhance our ability to produce nanoscale architectures. However, understanding their formation is a complex problem due to the interplay of geometric effects (entropy) and energetic interactions at the nanoscale. Spheres and rods are perhaps the most basic geometrical shapes and serve as convenient models of such dissimilar objects. The ordered phases formed by each of these individual shapes have already been explored, but, when mixed, spheres and rods have demonstrated only limited structural organization to date. We show using experiments and theory that the introduction of directional attractionsmore » between rod ends and isotropically interacting spherical nanoparticles (NPs) through DNA base pairing leads to the formation of ordered three-dimensional lattices. The spheres and rods arrange themselves in a complex alternating manner, where the spheres can form either a face-centered cubic (FCC) or hexagonal close-packed (HCP) lattice, or a disordered phase, as observed by in situ X-ray scattering. Increasing NP diameter at fixed rod length yields an initial transition from a disordered phase to the HCP crystal, energetically stabilized by rod-rod attraction across alternating crystal layers, as revealed by theory. In the limit of large NPs, the FCC structure is instead stabilized over the HCP by rod entropy. Thus, we propose that directionally specific attractions in mixtures of anisotropic and isotropic objects offer insight into unexplored self-assembly behavior of noncomplementary shaped particles.« less

Large-eddy simulation, fuel rod vibration and grid-to-rod fretting in pressurized water reactors

DOE PAGES

Christon, Mark A.; Lu, Roger; Bakosi, Jozsef; ...

2016-10-01

Grid-to-rod fretting (GTRF) in pressurized water reactors is a flow-induced vibration phenomenon that results in wear and fretting of the cladding material on fuel rods. GTRF is responsible for over 70% of the fuel failures in pressurized water reactors in the United States. Predicting the GTRF wear and concomitant interval between failures is important because of the large costs associated with reactor shutdown and replacement of fuel rod assemblies. The GTRF-induced wear process involves turbulent flow, mechanical vibration, tribology, and time-varying irradiated material properties in complex fuel assembly geometries. This paper presents a new approach for predicting GTRF induced fuelmore » rod wear that uses high-resolution implicit large-eddy simulation to drive nonlinear transient dynamics computations. The GTRF fluid–structure problem is separated into the simulation of the turbulent flow field in the complex-geometry fuel-rod bundles using implicit large-eddy simulation, the calculation of statistics of the resulting fluctuating structural forces, and the nonlinear transient dynamics analysis of the fuel rod. Ultimately, the methods developed here, can be used, in conjunction with operational management, to improve reactor core designs in which fuel rod failures are minimized or potentially eliminated. Furthermore, robustness of the behavior of both the structural forces computed from the turbulent flow simulations and the results from the transient dynamics analyses highlight the progress made towards achieving a predictive simulation capability for the GTRF problem.« less

Large-eddy simulation, fuel rod vibration and grid-to-rod fretting in pressurized water reactors

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

Christon, Mark A.; Lu, Roger; Bakosi, Jozsef

Grid-to-rod fretting (GTRF) in pressurized water reactors is a flow-induced vibration phenomenon that results in wear and fretting of the cladding material on fuel rods. GTRF is responsible for over 70% of the fuel failures in pressurized water reactors in the United States. Predicting the GTRF wear and concomitant interval between failures is important because of the large costs associated with reactor shutdown and replacement of fuel rod assemblies. The GTRF-induced wear process involves turbulent flow, mechanical vibration, tribology, and time-varying irradiated material properties in complex fuel assembly geometries. This paper presents a new approach for predicting GTRF induced fuelmore » rod wear that uses high-resolution implicit large-eddy simulation to drive nonlinear transient dynamics computations. The GTRF fluid–structure problem is separated into the simulation of the turbulent flow field in the complex-geometry fuel-rod bundles using implicit large-eddy simulation, the calculation of statistics of the resulting fluctuating structural forces, and the nonlinear transient dynamics analysis of the fuel rod. Ultimately, the methods developed here, can be used, in conjunction with operational management, to improve reactor core designs in which fuel rod failures are minimized or potentially eliminated. Furthermore, robustness of the behavior of both the structural forces computed from the turbulent flow simulations and the results from the transient dynamics analyses highlight the progress made towards achieving a predictive simulation capability for the GTRF problem.« less

Transesophageal Echocardiography, 3-Dimensional and Speckle Tracking Together as Sensitive Markers for Early Outcome in Patients With Left Ventricular Dysfunction Undergoing Cardiac Surgery.

PubMed

Kumar, Alok; Puri, Goverdhan Dutt; Bahl, Ajay

2017-10-01

Speckle tracking, when combined with 3-dimensional (3D) left ventricular ejection fraction, might prove to be a more sensitive marker for postoperative ventricular dysfunction. This study investigated early outcomes in a cohort of patients with left ventricular dysfunction undergoing cardiac surgery. Prospective, blinded, observational study. University hospital; single institution. The study comprised 73 adult patients with left ventricular ejection fraction <50% undergoing cardiac surgery using cardiopulmonary bypass. Routine transesophageal echocardiography before and after bypass. Global longitudinal strain using speckle tracking and 3D left ventricular ejection fraction were computed using transesophageal echocardiography. Mean prebypass global longitudinal strain and 3D left ventricle ejection fraction were significantly lower in patients with postoperative low-cardiac-output syndrome compared with patients who did not develop low cardiac output (global longitudinal strain -7.5% v -10.7% and 3D left ventricular ejection fraction 29% v 39%, respectively; p < 0.0001). The cut-off value of global longitudinal strain predicting postoperative low-cardiac-output syndrome was -6%, with 95% sensitivity and 68% specificity; and 3D left ventricular ejection fraction was 19% with 98% sensitivity and 81% specificity. Preoperative left ventricular global longitudinal strain (-6%) and 3D left ventricular ejection fraction (19%) together could act as predictor of postoperative low-cardiac-output states with high sensitivity (99.9%) in patients undergoing cardiac surgery. Copyright © 2017 Elsevier Inc. All rights reserved.

Mass ejection in failed supernovae: variation with stellar progenitor

NASA Astrophysics Data System (ADS)

Fernández, Rodrigo; Quataert, Eliot; Kashiyama, Kazumi; Coughlin, Eric R.

2018-05-01

We study the ejection of mass during stellar core-collapse when the stalled shock does not revive and a black hole forms. Neutrino emission during the protoneutron star phase causes a decrease in the gravitational mass of the core, resulting in an outward going sound pulse that steepens into a shock as it travels out through the star. We explore the properties of this mass ejection mechanism over a range of stellar progenitors using spherically symmetric, time-dependent hydrodynamic simulations that treat neutrino mass-loss parametrically and follow the shock propagation over the entire star. We find that all types of stellar progenitor can eject mass through this mechanism. The ejected mass is a decreasing function of the surface gravity of the star, ranging from several M⊙ for red supergiants to ˜0.1 M⊙ for blue supergiants and ˜10-3 M⊙ for Wolf-Rayet stars. We find that the final shock energy at the surface is a decreasing function of the core-compactness, and is ≲ 1047-1048 erg in all cases. In progenitors with a sufficiently large envelope, high core-compactness, or a combination of both, the sound pulse fails to unbind mass. Successful mass ejection is accompanied by significant fallback accretion that can last from hours to years. We predict the properties of shock breakout and thermal plateau emission produced by the ejection of the outer envelope of blue supergiant and Wolf-Rayet progenitors in otherwise failed supernovae.

Chromospheric Plasma Ejections in a Light Bridge of a Sunspot

NASA Astrophysics Data System (ADS)

Song, Donguk; Chae, Jongchul; Yurchyshyn, Vasyl; Lim, Eun-Kyung; Cho, Kyung-Suk; Yang, Heesu; Cho, Kyuhyoun; Kwak, Hannah

2017-02-01

It is well-known that light bridges (LBs) inside a sunspot produce small-scale plasma ejections and transient brightenings in the chromosphere, but the nature and origin of such phenomena are still unclear. Utilizing the high-spatial and high-temporal resolution spectral data taken with the Fast Imaging Solar Spectrograph and the TiO 7057 Å broadband filter images installed at the 1.6 m New Solar Telescope of Big Bear Solar Observatory, we report arcsecond-scale chromospheric plasma ejections (1.″7) inside a LB. Interestingly, the ejections are found to be a manifestation of upwardly propagating shock waves as evidenced by the sawtooth patterns seen in the temporal-spectral plots of the Ca II 8542 Å and Hα intensities. We also found a fine-scale photospheric pattern (1″) diverging with a speed of about 2 km s-1 two minutes before the plasma ejections, which seems to be a manifestation of magnetic flux emergence. As a response to the plasma ejections, the corona displayed small-scale transient brightenings. Based on our findings, we suggest that the shock waves can be excited by the local disturbance caused by magnetic reconnection between the emerging flux inside the LB and the adjacent umbral magnetic field. The disturbance generates slow-mode waves, which soon develop into shock waves, and manifest themselves as the arcsecond-scale plasma ejections. It also appears that the dissipation of mechanical energy in the shock waves can heat the local corona.

Linear theory on temporal instability of megahertz faraday waves for monodisperse microdroplet ejection.

PubMed

Tsai, Shirley C; Tsai, Chen S

2013-08-01

A linear theory on temporal instability of megahertz Faraday waves for monodisperse microdroplet ejection based on mass conservation and linearized Navier-Stokes equations is presented using the most recently observed micrometer- sized droplet ejection from a millimeter-sized spherical water ball as a specific example. The theory is verified in the experiments utilizing silicon-based multiple-Fourier horn ultrasonic nozzles at megahertz frequency to facilitate temporal instability of the Faraday waves. Specifically, the linear theory not only correctly predicted the Faraday wave frequency and onset threshold of Faraday instability, the effect of viscosity, the dynamics of droplet ejection, but also established the first theoretical formula for the size of the ejected droplets, namely, the droplet diameter equals four-tenths of the Faraday wavelength involved. The high rate of increase in Faraday wave amplitude at megahertz drive frequency subsequent to onset threshold, together with enhanced excitation displacement on the nozzle end face, facilitated by the megahertz multiple Fourier horns in resonance, led to high-rate ejection of micrometer- sized monodisperse droplets (>10(7) droplets/s) at low electrical drive power (<;1 W) with short initiation time (<;0.05 s). This is in stark contrast to the Rayleigh-Plateau instability of a liquid jet, which ejects one droplet at a time. The measured diameters of the droplets ranging from 2.2 to 4.6 μm at 2 to 1 MHz drive frequency fall within the optimum particle size range for pulmonary drug delivery.

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.

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

Adigun, Babatunde John; Fensin, Michael Lorne; Galloway, Jack D.

Our burnup study examined the effect of a predicted critical control rod position on the nuclide predictability of several axial and radial locations within a 4×4 graphite moderated gas cooled reactor fuel cluster geometry. To achieve this, a control rod position estimator (CRPE) tool was developed within the framework of the linkage code Monteburns between the transport code MCNP and depletion code CINDER90, and four methodologies were proposed within the tool for maintaining criticality. Two of the proposed methods used an inverse multiplication approach - where the amount of fissile material in a set configuration is slowly altered until criticalitymore » is attained - in estimating the critical control rod position. Another method carried out several MCNP criticality calculations at different control rod positions, then used a linear fit to estimate the critical rod position. The final method used a second-order polynomial fit of several MCNP criticality calculations at different control rod positions to guess the critical rod position. The results showed that consistency in prediction of power densities as well as uranium and plutonium isotopics was mutual among methods within the CRPE tool that predicted critical position consistently well. Finall, while the CRPE tool is currently limited to manipulating a single control rod, future work could be geared toward implementing additional criticality search methodologies along with additional features.« less

Terahertz artificial material based on integrated metal-rod-array for phase sensitive fluid detection.

PubMed

You, Borwen; Chen, Ching-Yu; Yu, Chin-Ping; Liu, Tze-An; Hattori, Toshiaki; Lu, Ja-Yu

2017-04-17

A terahertz artificial material composed of metal rod array is experimentally investigated on its transmission spectral property and successfully incorporated into microfluidics as a miniaturized terahertz waveguide with an extended optical-path-length for label-free fluidic sensing. Theoretical and experimental characterizations of terahertz transmission spectra show that the wave guidance along the metal rod array originates from the resonance of transverse-electric-polarized waves within the metal rod slits. The extended optical path length along three layers of metal-rod-array enables terahertz waves sufficiently overlapping the fluid molecules embedded among the rods, leading to strongly enhanced phase change by approximately one order of magnitude compared with the blank metal-parallel-plate waveguide. Based on the enhanced phase sensitivity, three kinds of colorless liquid analytes, namely, acetone, methanol, and ethanol, with different dipole moments are identified in situ using the metal-rod-array-based microfluidic sensor. The detection limit in molecular amounts of a liquid analyte is experimentally demonstrated to be less than 0.1 mmol, corresponding to 2.7 μmol/mm². The phase sensitive terahertz metal-rod-array-based sensor potentially has good adaptability in lab-chip technology for various practical applications, such as industrial toxic fluid detection and medical breath inspection.

Samd7 is a cell type-specific PRC1 component essential for establishing retinal rod photoreceptor identity

PubMed Central

Omori, Yoshihiro; Kubo, Shun; Kon, Tetsuo; Furuhashi, Mayu; Narita, Hirotaka; Kominami, Taro; Ueno, Akiko; Tsutsumi, Ryotaro; Chaya, Taro; Yamamoto, Haruka; Suetake, Isao; Ueno, Shinji; Koseki, Haruhiko; Furukawa, Takahisa

2017-01-01

Precise transcriptional regulation controlled by a transcription factor network is known to be crucial for establishing correct neuronal cell identities and functions in the CNS. In the retina, the expression of various cone and rod photoreceptor cell genes is regulated by multiple transcription factors; however, the role of epigenetic regulation in photoreceptor cell gene expression has been poorly understood. Here, we found that Samd7, a rod-enriched sterile alpha domain (SAM) domain protein, is essential for silencing nonrod gene expression through H3K27me3 regulation in rod photoreceptor cells. Samd7-null mutant mice showed ectopic expression of nonrod genes including S-opsin in rod photoreceptor cells and rod photoreceptor cell dysfunction. Samd7 physically interacts with Polyhomeotic homologs (Phc proteins), components of the Polycomb repressive complex 1 (PRC1), and colocalizes with Phc2 and Ring1B in Polycomb bodies. ChIP assays showed a significant decrease of H3K27me3 in the genes up-regulated in the Samd7-deficient retina, showing that Samd7 deficiency causes the derepression of nonrod gene expression in rod photoreceptor cells. The current study suggests that Samd7 is a cell type-specific PRC1 component epigenetically defining rod photoreceptor cell identity. PMID:28900001

Samd7 is a cell type-specific PRC1 component essential for establishing retinal rod photoreceptor identity.

PubMed

Omori, Yoshihiro; Kubo, Shun; Kon, Tetsuo; Furuhashi, Mayu; Narita, Hirotaka; Kominami, Taro; Ueno, Akiko; Tsutsumi, Ryotaro; Chaya, Taro; Yamamoto, Haruka; Suetake, Isao; Ueno, Shinji; Koseki, Haruhiko; Nakagawa, Atsushi; Furukawa, Takahisa

2017-09-26

Precise transcriptional regulation controlled by a transcription factor network is known to be crucial for establishing correct neuronal cell identities and functions in the CNS. In the retina, the expression of various cone and rod photoreceptor cell genes is regulated by multiple transcription factors; however, the role of epigenetic regulation in photoreceptor cell gene expression has been poorly understood. Here, we found that Samd7, a rod-enriched sterile alpha domain (SAM) domain protein, is essential for silencing nonrod gene expression through H3K27me3 regulation in rod photoreceptor cells. Samd7- null mutant mice showed ectopic expression of nonrod genes including S-opsin in rod photoreceptor cells and rod photoreceptor cell dysfunction. Samd7 physically interacts with Polyhomeotic homologs (Phc proteins), components of the Polycomb repressive complex 1 (PRC1), and colocalizes with Phc2 and Ring1B in Polycomb bodies. ChIP assays showed a significant decrease of H3K27me3 in the genes up-regulated in the Samd7 -deficient retina, showing that Samd7 deficiency causes the derepression of nonrod gene expression in rod photoreceptor cells. The current study suggests that Samd7 is a cell type-specific PRC1 component epigenetically defining rod photoreceptor cell identity.

Protrusion of a rod into the spinal canal 10 years after segmental lumbar spine surgery.

PubMed

Cai, Siyi; Kong, Xiangyi; Yan, Chengrui; Wang, Yipeng; Wan, Xueshuai; Zhang, Jialu; Qiu, Guixing; Yu, Keyi

2017-03-01

The objective of this article is to report an unusual case of a spinal rod that protruded into the spinal canal after lumbar spine surgery.Only 4 cases of spinal rod migration with protrusion into the spinal canal have been reported. This is the first report of a case involving the use of posterior low lumbar segmental instrumentation with a screw-rod system. The left side of the rod gradually migrated and finally protruded into the canal and compressed the cord.A 60-year-old woman presented with pain and numbness of the posterior aspect of the left leg after a long-distance walk. Intermittent claudication became worse, and she developed pain and numbness in the perineal region. An x-ray showed that the left side of a spinal rod among the segmental spinal instruments that had been placed 10 years previously had protruded into the spinal canal.We removed the rod and decompressed the canal at the level of L5-S1. The patient became totally asymptomatic.Rods used as spinal instrumentation have the possibility of protruding into the spinal canal and endangering the nervous system. Long-term follow-up with radiological examinations should be conducted upon completion of spinal operations conducting using instrumentation.

Investigation of the processing conditions for the synthesis of rod-shaped LiCoO2

NASA Astrophysics Data System (ADS)

Kim, Taejoong; Kim, Yongseon

2018-07-01

We investigate the processing conditions for the synthesis of rod-shaped LiCoO2 (LCO) by a solid-state calcination of a precursor material which was prepared by a hydrothermal method. The rod-like morphology appeared to be easily broken due to the growth of primary crystals recrystallized during the calcination process. Therefore, it is crucial to maintain the temperature under a certain limit. However, the temperature must be high enough to obtain proper crystallinity of the LCO, ideally above 800 °C. Thus, we determined the optimal calcination temperature condition from the common range of temperatures that satisfies both these limiting conditions. The precursor with average diameter of 1 µm sustained the rod shape at calcination temperatures of up to 900 °C; therefore, the optimum calcination temperature could be determined between 800 and 900 °C. Whereas, a proper calcination temperature could not be found for the precursor with 500 nm of diameter because the rod shape did not maintain even at 700 °C. Thus, the maximum temperature at which the rod shape is retained decreases with smaller diameter of the precursor rods, indicating adjusting the diameter above a limiting value is necessary to prepare LCO rod by conventional solid state calcination.

LOGIC CIRCUIT

DOEpatents

Strong, G.H.; Faught, M.L.

1963-12-24

A device for safety rod counting in a nuclear reactor is described. A Wheatstone bridge circuit is adapted to prevent de-energizing the hopper coils of a ball backup system if safety rods, sufficient in total control effect, properly enter the reactor core to effect shut down. A plurality of resistances form one arm of the bridge, each resistance being associated with a particular safety rod and weighted in value according to the control effect of the particular safety rod. Switching means are used to switch each of the resistances in and out of the bridge circuit responsive to the presence of a particular safety rod in its effective position in the reactor core and responsive to the attainment of a predetermined velocity by a particular safety rod enroute to its effective position. The bridge is unbalanced in one direction during normal reactor operation prior to the generation of a scram signal and the switching means and resistances are adapted to unbalance the bridge in the opposite direction if the safety rods produce a predetermined amount of control effect in response to the scram signal. The bridge unbalance reversal is then utilized to prevent the actuation of the ball backup system, or, conversely, a failure of the safety rods to produce the predetermined effect produces no unbalance reversal and the ball backup system is actuated. (AEC)

Hierarchical Nanostructures Self-Assembled from a Mixture System Containing Rod-Coil Block Copolymers and Rigid Homopolymers

PubMed Central

Li, Yongliang; Jiang, Tao; Lin, Shaoliang; Lin, Jiaping; Cai, Chunhua; Zhu, Xingyu

2015-01-01

Self-assembly behavior of a mixture system containing rod-coil block copolymers and rigid homopolymers was investigated by using Brownian dynamics simulations. The morphologies of formed hierarchical self-assemblies were found to be dependent on the Lennard-Jones (LJ) interaction εRR between rod blocks, lengths of rod and coil blocks in copolymer, and mixture ratio of block copolymers to homopolymers. As the εRR value decreases, the self-assembled structures of mixtures are transformed from an abacus-like structure to a helical structure, to a plain fiber, and finally are broken into unimers. The order parameter of rod blocks was calculated to confirm the structure transition. Through varying the length of rod and coil blocks, the regions of thermodynamic stability of abacus, helix, plain fiber, and unimers were mapped. Moreover, it was discovered that two levels of rod block ordering exist in the helices. The block copolymers are helically wrapped on the homopolymer bundles to form helical string, while the rod blocks are twistingly packed inside the string. In addition, the simulation results are in good agreement with experimental observations. The present work reveals the mechanism behind the formation of helical (experimentally super-helical) structures and may provide useful information for design and preparation of the complex structures. PMID:25965726

Measuring axial pump thrust

DOEpatents

Suchoza, Bernard P.; Becse, Imre

1988-01-01

An apparatus for measuring the hydraulic axial thrust of a pump under operation conditions is disclosed. The axial thrust is determined by forcing the rotating impeller off of an associated thrust bearing by use of an elongate rod extending coaxially with the pump shaft. The elongate rod contacts an impeller retainer bolt where a bearing is provided. Suitable measuring devices measure when the rod moves to force the impeller off of the associated thrust bearing and the axial force exerted on the rod at that time. The elongate rod is preferably provided in a housing with a heat dissipation mechanism whereby the hot fluid does not affect the measuring devices.

Measuring axial pump thrust

DOEpatents

Suchoza, B.P.; Becse, I.

1988-11-08

An apparatus for measuring the hydraulic axial thrust of a pump under operation conditions is disclosed. The axial thrust is determined by forcing the rotating impeller off of an associated thrust bearing by use of an elongate rod extending coaxially with the pump shaft. The elongate rod contacts an impeller retainer bolt where a bearing is provided. Suitable measuring devices measure when the rod moves to force the impeller off of the associated thrust bearing and the axial force exerted on the rod at that time. The elongate rod is preferably provided in a housing with a heat dissipation mechanism whereby the hot fluid does not affect the measuring devices. 1 fig.

PWR FLECHT SEASET 163-Rod Bundle Flow Blockage Task data report. NRC/EPRI/Westinghouse report No. 13, August-October 1982

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

Loftus, M J; Hochreiter, L E; McGuire, M F

This report presents data from the 163-Rod Bundle Blow Blockage Task of the Full-Length Emergency Cooling Heat Transfer Systems Effects and Separate Effects Test Program (FLECHT SEASET). The task consisted of forced and gravity reflooding tests utilizing electrical heater rods with a cosine axial power profile to simulate PWR nuclear core fuel rod arrays. These tests were designed to determine effects of flow blockage and flow bypass on reflooding behavior and to aid in the assessment of computational models in predicting the reflooding behavior of flow blockage in rod bundle arrays.

An analytical model for inductively coupled implantable biomedical devices with ferrite rods.

PubMed

Theilmann, P T; Asbeck, P M

2009-02-01

Using approximations applicable to near field coupled implants simplified expressions for the complex mutual inductance of coaxial aligned coils with and without a cylindrical ferrite rod are derived. Experimental results for ferrite rods of various sizes and permeabilities are presented to verify the accuracy of this expression. An equivalent circuit model for the inductive link between an implant and power coil is then presented and used to investigate how ferrite size, permeability and loss affect the power available to the implant device. Enhancements in coupling provided by high frequency, low permeability nickel zinc rods are compared with low frequency high permeability manganese zinc rods.

Two-stage epitaxial growth of vertically-aligned SnO 2 nano-rods on(001) ceria

DOE PAGES

Solovyov, Vyacheslav F.; Wu, Li-jun; Rupich, Martin W.; ...

2014-09-20

Growth of high-aspect ratio oriented tin oxide, SnO 2, nano-rods is complicated by a limited choice of matching substrates. We show that a (001) cerium oxide, CeO 2, surface uniquely enables epitaxial growth of tin-oxide nano-rods via a two-stage process. First, (100) oriented nano-wires coat the ceria surface by lateral growth, forming a uniaxially-textured SnO 2 deposit. Second, vertical SnO 2nano-rods nucleate on the deposit by homoepitaxy. We demonstrate growth of vertically oriented 1-2 μm long nano-rods with an average diameter of ≈20 nm.

Development and Assessment of a New CFRP Rod Anchor System for Prestressed Concrete

NASA Astrophysics Data System (ADS)

Al-Mayah, A.; Soudki, K.; Plumtree, A.

2006-09-01

Design concepts and experimental assessment of a new wedge anchor system for prestressing CFRP rods are presented. This compact and reusable anchor consists of an outer cylinder (barrel), a number of wedges, and a soft metal sleeve. The contacting surfaces of the wedges and barrel have a circular profile along the length of the anchor. Tensile testing using different presetting loads, geometric configurations, and rod sizes was carried out. The relationship of the tensile load and displacement of the rod was established. Presetting was found unnecessary since the anchor system was found to be capable of carrying the full design strength of the rods.

REMOTELY OPERATED MANIPULATOR

DOEpatents

Hutto, E.L.

1961-08-15

A manipulator is described for performing, within an entirely enclosed cell containling radioactive materials, various mechanical operations. A rod with flexible fingers is encompassed by a tubular sleeve shorter than the rod. Relative movement between the rod and sleeve causes the fingers to open and close. This relative movement is effected by relative movement of permanent magnets in magnetic coupling relation to magnetic followers affixed to the ends of the rod and sleeve. The rod and its sleeve may be moved as a unit axially or may be rotated by means of the magnetic couplings. The manipulator is enclosed within a tubular member which is flexibly sealed to an opening in the cell. (AEC)

Method and apparatus for reading lased bar codes on shiny-finished fuel rod cladding tubes

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

Goldenfield, M.P.; Lambert, D.V.

1990-10-02

This patent describes, in a nuclear fuel rod identification system, a method of reading a bar code etched directly on a surface of a nuclear fuel rod. It comprises: defining a pair of light diffuser surfaces adjacent one another but in oppositely inclined relation to a beam of light emitted from a light reader; positioning a fuel rod, having a cylindrical surface portion with a bar code etched directly thereon, relative to the light diffuser surfaces such that the surfaces are disposed adjacent to and in oppositely inclined relation along opposite sides of the fuel rod surface portion and themore » fuel rod surface portion is aligned with the beam of light emitted from the light reader; directing the beam of light on the bar code on fuel rod cylindrical surface portion such that the light is reflected therefrom onto one of the light diffuser surfaces; and receiving and reading the reflected light from the bar code via the one of the light diffuser surfaces to the light reader.« less

Close packing of rods on spherical surfaces

NASA Astrophysics Data System (ADS)

Smallenburg, Frank; Löwen, Hartmut

2016-04-01

We study the optimal packing of short, hard spherocylinders confined to lie tangential to a spherical surface, using simulated annealing and molecular dynamics simulations. For clusters of up to twelve particles, we map out the changes in the geometry of the closest-packed configuration as a function of the aspect ratio L/D, where L is the cylinder length and D the diameter of the rods. We find a rich variety of cluster structures. For larger clusters, we find that the best-packed configurations up to around 100 particles are highly dependent on the exact number of particles and aspect ratio. For even larger clusters, we find largely disordered clusters for very short rods (L/D = 0.25), while slightly longer rods (L/D = 0.5 or 1) prefer a global baseball-like geometry of smectic-like domains, similar to the behavior of large-scale nematic shells. Intriguingly, we observe that when compared to their optimal flat-plane packing, short rods adapt to the spherical geometry more efficiently than both spheres and longer rods. Our results provide predictions for experimentally realizable systems of colloidal rods trapped at the interface of emulsion droplets.

Measurements of Induced-Charge Electroosmotic Flow Around a Metallic Rod

NASA Astrophysics Data System (ADS)

Beskok, Ali; Canpolat, Cetin

2012-11-01

A cylindrical gold-coated stainless steel rod was positioned at the center of a straight microchannel connecting two fluid reservoirs on either end. The microchannel was filled with 1 mM KCl containing 0.5 micron diameter carboxylate-modified spherical particles. Induced-charge electro-osmotic (ICEO) flow occurred around the metallic rod under a sinusoidal AC electric field applied using two platinum electrodes. The ICEO flows around the metallic rod were measured using micro particle image velocimetry (micro-PIV) technique as functions of the AC electric field strength and frequency. The present study provides experimental data about ICEO flow in the weakly nonlinear limit of thin double layers, in which, the charging dynamics of the double layer cannot be presented analytically. Flow around the rod is quadrupolar, driving liquid towards the rod along the electric field and forcing it away from the rod in the direction perpendicular to the imposed electric field. The measured ICEO flow velocity is proportional to the square of the electric field strength, and depends on the applied AC frequency.

Double angle seal forming lubricant film

DOEpatents

Ernst, William D.

1984-01-01

A lubricated piston rod seal which inhibits gas leaking from a high pressure chamber on one side of the seal to a low pressure chamber on the other side of the seal. A liquid is supplied to the surface of the piston rod on the low pressure side of the seal. This liquid acts as lubricant for the seal and provides cooling for the rod. The seal, which can be a plastic, elastomer or other material with low elastic modulus, is designed to positively pump lubricant through the piston rod/seal interface in both directions when the piston rod is reciprocating. The capacity of the seal to pump lubricant from the low pressure side to the high pressure side is less than its capacity to pump lubricant from the high pressure side to the low pressure side which ensures that there is zero net flow of lubricant to the high pressure side of the seal. The film of lubricant between the seal and the rod minimizes any sliding contact and prevents the leakage of gas. Under static conditions gas leakage is prevented by direct contact between the seal and the rod.

Distributed temperature sensing inside a 19-rod bundle

DOE PAGES

Lomperski, S.; Bremer, N.; Gerardi, C.

2017-05-23

The temperature field within a model of a sodium-cooled fast reactor fuel rod bundle was measured using Ø155 μm fiber optic distributed temperature sensors (DTS). The bundle consists of 19 electrically-heated rods Ø6.3 mm and 865 mm long. Working fluids were argon and air at atmospheric pressure and Reynolds numbers up to 300. A 20 m-long DTS was threaded through Ø1 mm capillaries wound around rods as wire-wraps. The sensor generated 173 measurements along each rod at 5 mm resolution for a total of 3300 data locations. A second DTS, 58 m long, was suspended between rods to provide 9300more » fluid temperature measurements at 20 mm resolution. Such data density makes it possible to construct 3D maps of the temperature field that are beyond the reach of traditional sensors such as thermocouples. This is illustrated through a series of steady-state and transient tests. As a result, the work demonstrates the feasibility of mapping temperature within the close confines of a rod bundle at resolutions suitable for validation of computational fluid dynamics codes.« less

Fission gas release restrictor for breached fuel rod

DOEpatents

Kadambi, N. Prasad; Tilbrook, Roger W.; Spencer, Daniel R.; Schwallie, Ambrose L.

1986-01-01

In the event of a breach in the cladding of a rod in an operating liquid metal fast breeder reactor, the rapid release of high-pressure gas from the fission gas plenum may result in a gas blanketing of the breached rod and rods adjacent thereto which impairs the heat transfer to the liquid metal coolant. In order to control the release rate of fission gas in the event of a breached rod, the substantial portion of the conventional fission gas plenum is formed as a gas bottle means which includes a gas pervious means in a small portion thereof. During normal reactor operation, as the fission gas pressure gradually increases, the gas pressure interiorly of and exteriorly of the gas bottle means equalizes. In the event of a breach in the cladding, the gas pervious means in the gas bottle means constitutes a sufficient restriction to the rapid flow of gas therethrough that under maximum design pressure differential conditions, the fission gas flow through the breach will not significantly reduce the heat transfer from the affected rod and adjacent rods to the liquid metal heat transfer fluid flowing therebetween.

Not just signal shutoff: the protective role of arrestin-1 in rod cells.

PubMed

Sommer, Martha E; Hofmann, Klaus Peter; Heck, Martin

2014-01-01

The retinal rod cell is an exquisitely sensitive single-photon detector that primarily functions in dim light (e.g., moonlight). However, rod cells must routinely survive light intensities more than a billion times greater (e.g., bright daylight). One serious challenge to rod cell survival in daylight is the massive amount of all-trans-retinal that is released by Meta II, the light-activated form of the photoreceptor rhodopsin. All-trans-retinal is toxic, and its condensation products have been implicated in disease. Our recent work has developed the concept that rod arrestin (arrestin-1), which terminates Meta II signaling, has an additional role in protecting rod cells from the consequences of bright light by limiting free all-trans-retinal. In this chapter we will elaborate upon the molecular mechanisms by which arrestin-1 serves as both a single-photon response quencher as well as an instrument of rod cell survival in bright light. This discussion will take place within the framework of three distinct functional modules of vision: signal transduction, the retinoid cycle, and protein translocation.

Evaluation of training nurses to perform semi-automated three-dimensional left ventricular ejection fraction using a customised workstation-based training protocol.

PubMed

Guppy-Coles, Kristyan B; Prasad, Sandhir B; Smith, Kym C; Hillier, Samuel; Lo, Ada; Atherton, John J

2015-06-01

We aimed to determine the feasibility of training cardiac nurses to evaluate left ventricular function utilising a semi-automated, workstation-based protocol on three dimensional echocardiography images. Assessment of left ventricular function by nurses is an attractive concept. Recent developments in three dimensional echocardiography coupled with border detection assistance have reduced inter- and intra-observer variability and analysis time. This could allow abbreviated training of nurses to assess cardiac function. A comparative, diagnostic accuracy study evaluating left ventricular ejection fraction assessment utilising a semi-automated, workstation-based protocol performed by echocardiography-naïve nurses on previously acquired three dimensional echocardiography images. Nine cardiac nurses underwent two brief lectures about cardiac anatomy, physiology and three dimensional left ventricular ejection fraction assessment, before a hands-on demonstration in 20 cases. We then selected 50 cases from our three dimensional echocardiography library based on optimal image quality with a broad range of left ventricular ejection fractions, which was quantified by two experienced sonographers and the average used as the comparator for the nurses. Nurses independently measured three dimensional left ventricular ejection fraction using the Auto lvq package with semi-automated border detection. The left ventricular ejection fraction range was 25-72% (70% with a left ventricular ejection fraction <55%). All nurses showed excellent agreement with the sonographers. Minimal intra-observer variability was noted on both short-term (same day) and long-term (>2 weeks later) retest. It is feasible to train nurses to measure left ventricular ejection fraction utilising a semi-automated, workstation-based protocol on previously acquired three dimensional echocardiography images. Further study is needed to determine the feasibility of training nurses to acquire three dimensional echocardiography images on real-world patients to measure left ventricular ejection fraction. Nurse-performed evaluation of left ventricular function could facilitate the broader application of echocardiography to allow cost-effective screening and monitoring for left ventricular dysfunction in high-risk populations. © 2014 John Wiley & Sons Ltd.

Benefits of Permanent His Bundle Pacing Combined With Atrioventricular Node Ablation in Atrial Fibrillation Patients With Heart Failure With Both Preserved and Reduced Left Ventricular Ejection Fraction.

PubMed

Huang, Weijian; Su, Lan; Wu, Shengjie; Xu, Lei; Xiao, Fangyi; Zhou, Xiaohong; Ellenbogen, Kenneth A

2017-04-01

Clinical benefits from His bundle pacing (HBP) in heart failure patients with preserved and reduced left ventricular ejection fraction are still inconclusive. This study evaluated clinical outcomes of permanent HBP in atrial fibrillation patients with narrow QRS who underwent atrioventricular node ablation for heart failure symptoms despite rate control by medication. The study enrolled 52 consecutive heart failure patients who underwent attempted atrioventricular node ablation and HBP for symptomatic atrial fibrillation. Echocardiographic left ventricular ejection fraction and left ventricular end-diastolic dimension, New York Heart Association classification and use of diuretics for heart failure were assessed during follow-up visits after permanent HBP. Of 52 patients, 42 patients (80.8%) received permanent HBP and atrioventricular node ablation with a median 20-month follow-up. There was no significant change between native and paced QRS duration (107.1±25.8 versus 105.3±23.9 milliseconds, P =0.07). Left ventricular end-diastolic dimension decreased from the baseline ( P <0.001), and left ventricular ejection fraction increased from baseline ( P <0.001) in patients with a greater improvement in heart failure with reduced ejection fraction patients (N=20) than in heart failure with preserved ejection fraction patients (N=22). New York Heart Association classification improved from a baseline 2.9±0.6 to 1.4±0.4 after HBP in heart failure with reduced ejection fraction patients and from a baseline 2.7±0.6 to 1.4±0.5 after HBP in heart failure with preserved ejection fraction patients. After 1 year of HBP, the numbers of patients who used diuretics for heart failure decreased significantly ( P <0.001) when compared to the baseline diuretics use. Permanent HBP post-atrioventricular node ablation significantly improved echocardiographic measurements and New York Heart Association classification and reduced diuretics use for heart failure management in atrial fibrillation patients with narrow QRS who suffered from heart failure with preserved or reduced ejection fraction. © 2017 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley Blackwell.

Improved composite material and method for production of improved composite material

NASA Technical Reports Server (NTRS)

Farley, Gary L. (Inventor)

1994-01-01

A laminated composite material with improved interlaminar strength and damage tolerance having short rods distributed evenly throughout the composite material perpendicular to the laminae is introduced. Each rod is shorter than the thickness of the finished laminate, but several times as long as the thickness of each lamina. The laminate is made by inserting short rods in layers of prepreg material, and then stacking and curing prepreg material with rods inserted therethrough.

High-Power Pinched-Beam Diode Development for Radiographic Applications

DTIC Science & Technology

2007-06-01

reentrant rods. II. X-RAY DIAGNOSTICS The x-ray dose is measured using CaF2 thermoluminescent dosimeters ( TLDs ) enclosed in 1-cm- diam...1.5-mm spot size. This paper reports on studies of the rod-pinch (RP) diode [3], comprising a small anode rod and an annular cathode. Electrons ...because the electrons impact the rod primarily in the backwards direction. As the voltage increases, the x- radiation becomes more forward-peaked

Fission control system for nuclear reactor

DOEpatents

Conley, G.H.; Estes, G.P.

Control system for nuclear reactor comprises a first set of reactivity modifying rods fixed in a reactor core with their upper ends stepped in height across the core, and a second set of reactivity modifying rods movable vertically within the reactor core and having their lower ends stepped to correspond with the stepped arrangement of the first set of rods, pairs of the rods of the first and second sets being in coaxial alignment.

Evaluation of the finite element fuel rod analysis code (FRANCO)

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

Lee, K.; Feltus, M.A.

1994-12-31

Knowledge of temperature distribution in a nuclear fuel rod is required to predict the behavior of fuel elements during operating conditions. The thermal and mechanical properties and performance characteristics are strongly dependent on the temperature, which can vary greatly inside the fuel rod. A detailed model of fuel rod behavior can be described by various numerical methods, including the finite element approach. The finite element method has been successfully used in many engineering applications, including nuclear piping and reactor component analysis. However, fuel pin analysis has traditionally been carried out with finite difference codes, with the exception of Electric Powermore » Research Institute`s FREY code, which was developed for mainframe execution. This report describes FRANCO, a finite element fuel rod analysis code capable of computing temperature disrtibution and mechanical deformation of a single light water reactor fuel rod.« less