bluuebunny/crossref_metadata_2025 huggingface dataset:
Phosphodiesterase-5 Inhibitor, Tadalafil, Protects Against Myocardial Ischemia/Reperfusion Through Protein-Kinase G–Dependent Generation of Hydrogen Sulfide
Authors: Salloum Fadi N. , Chau Vinh Q. , Hoke Nicholas N. , Abbate Antonio , Varma Amit , Ockaili Ramzi A. , Toldo Stefano , Kukreja Rakesh C.
Published: September 2009

Background—

Tadalafil is a novel long-acting inhibitor of phosphodiesterase-5. Because cGMP-dependent protein kinase (PKG) signaling plays a key role in cardioprotection, we hypothesized that PKG activation with tadalafil would limit myocardial ischemia/reperfusion (I/R) injury and dysfunction. Additionally, we contemplated that cardioprotection with tadalafil is mediated by hydrogen sulfide (H
2
S) signaling in a PKG-dependent fashion.

Methods and Results—

After baseline transthoracic echocardiography (TTE), adult ICR mice were injected i.p. with vehicle (10% DMSO) or tadalafil (1 mg/kg) with or without KT5823 (KT, PKG blocker, 1 mg/kg) or dl-propargylglycine (PAG, Cystathionine-γ-lyase [CSE, H
2
S-producing enzyme] blocker; 50 mg/kg) 1 hour before coronary artery ligation for 30 minutes and reperfusion for 24 hours, whereas C57BL wild-type and CSE-knockout mice were treated with either vehicle or tadalafil. After reperfusion, TTE was performed and hearts were collected for infarct size (IS) measurement using TTC staining. Survival was increased with tadalafil (95%) compared with control (65%,
P
<0.05). Infarct size was reduced with tadalafil (13.2±1.7%) compared to vehicle (40.6±2.5%;
P
<0.05). KT and PAG abolished tadalafil-induced protection (IS: 39.2±1% and 51.2±2.4%, respectively) similar to genetic deletion of CSE (47.2±5.1%). Moreover, tadalafil preserved fractional shortening (FS: 31±1.5%) compared to control (FS: 22±4.8%,
P
<0.05). Baseline FS was 44±1.7%. KT and PAG abrogated the preservation of LV function with tadalafil by decline in FS to 17±1% and 23±3%, respectively. Compared to vehicle, myocardial H
2
S production was significantly increased with tadalafil and was abolished with KT.

Conclusion—

PKG activation with tadalafil limits myocardial infarction and preserves LV function through H
2
S signaling.
Mitral Leaflet Adaptation to Ventricular Remodeling
Authors: Chaput Miguel , Handschumacher Mark D. , Guerrero J. Luis , Holmvang Godtfred , Dal-Bianco Jacob P. , Sullivan Suzanne , Vlahakes Gus J. , Hung Judy , Levine Robert A.
Published: September 2009

Background—

Ischemic mitral regurgitation is caused by systolic traction on the mitral leaflets related to ventricular distortion. Little is known about how chronic tethering affects leaflet area, in part because it cannot be measured repeatedly in situ. Recently, a new method for 3D echocardiographic measurement of mitral leaflet area was developed and validated in vivo against sheep valves, later excised. Clinical studies (n=80) showed that mitral leaflet area increased by >30% in patients with inferior myocardial infarction and dilated cardiomyopathy versus normal; greater adaptation independently predicted less mitral regurgitation. This study explored whether mitral valve area changes over time within the same heart with ischemic mitral regurgitation.

Methods and Results—

Twelve sheep were studied at baseline and 3 months after inferior myocardial infarction by 3D echocardiography; 6 were untreated and 6 were treated initially with an epicardial patch to limit left ventricular dilation and mitral regurgitation. Untreated sheep developed left ventricular dilation at 3 months, with global dysfunction (mean±SD ejection fraction, 24±10% versus 44±10% with patching,
P
=0.02) and moderate mitral regurgitation (vena contracta, 5.0±1.0 versus 0.8±1.0 mm,
P
<0.0002). In untreated sheep, total diastolic leaflet area increased from 13.1±1.3 to 18.1±2.5 cm
2
(
P
=0.0001). In patched sheep, leaflet area at 3 months was not significantly different from baseline sheep values (13.0±1.1 versus baseline, 12.1±1.8 cm
2
,
P
=0.31).

Conclusions—

Mitral valve area, independent of systolic stretch, increases over time as the left ventricular remodels after inferior myocardial infarction. This increase, however, fails to compensate adequately for tethering to prevent mitral regurgitation. Understanding the mechanism of valve adaptation can potentially suggest new biological and surgical therapeutic targets.
A Case Study of the Mechanics of Extratropical Influence on the Initiation of the Madden–Julian Oscillation
Authors: Ray Pallav , Zhang Chidong
Published: September 2009

Mechanisms for extratropical influences on the initiation of the Madden–Julian oscillation (MJO) are investigated using numerical simulations and a global reanalysis product. Previous simulations by a tropical channel model captured the timing and gross features of the initiations of two MJO events and suggested that the initiations were due to influences from the extratropics. In this study, latitudinal transport of momentum from the extratropics is found to be crucial in generating the lower tropospheric westerlies in the tropics associated with the MJO initiation. The diagnoses of the zonal momentum budget for the MJO initiation region revealed that the advection by meridional winds could be important prior to the initiation of the MJO. The time evolution of the wave activity identifies its source over the southern Indian Ocean where it grows by extracting kinetic energy from the mean flow. The time scale of the lateral boundary conditions that is responsible for the MJO initiation is also investigated. The implications of the results and limitations of the approach are discussed.
Finite-Amplitude Equilibration of Baroclinic Waves on a Jet
Authors: Lee Sukyoung
Published: September 2009

A two-layer quasigeostrophic model is used to study the equilibration of baroclinic waves. In this model, if the background flow is relaxed toward a jetlike profile, a finite-amplitude baroclinic wave solution can be realized in both supercritical and subcritical regions of the model’s parameter space. Analyses of the model equations and numerical model calculations indicate that the finite-amplitude wave equilibration hinges on the breaking of Rossby waves before they reach their critical latitude. This “jetward” wave breaking results in an increase in the upper-layer wave generation and a reduction in the vertical phase tilt. This change in the phase tilt has a substantial impact on the Ekman pumping, as it weakens the damping on the lower-layer wave for some parameter settings and enables the Ekman pumping to serve as a source of wave growth at other settings. Together, these processes can account for the O(1)-amplitude wave equilibration.

From a potential vorticity (PV) perspective, the wave breaking reduces the meridional scale of the upper-layer eddy PV flux, which destabilizes the mean flow. This is followed by a strengthening of the lower-layer eddy PV flux, which weakens the lower-layer PV gradient and constrains the growth of the lower-layer eddy PV. The same jetward wave breaking focuses the upper-layer PV flux toward the jet center where the upper-layer PV gradient is greatest. This results in an intensification of the upper-layer eddy PV relative to lower-layer eddy PV. Because of this large ratio, the upper-layer eddy PV plays the primary role in inducing the upper- and lower-layer eddy streamfunction fields, decreasing the vertical phase tilt. As a result, the Ekman pumping on the eddies is weakened, and for some parameter settings the Ekman pumping can even act as a wave source, contributing toward O(1)-amplitude wave equilibration. By reducing the horizontal shear of the zonal wind, the same wave breaking process weakens the barotropic decay, which also contributes to the wave amplification.
Submonthly Indian Ocean Cooling Events and Their Interaction with Large-Scale Conditions
Authors: Lloyd Ian D. , Vecchi Gabriel A.
Published: September 2009

The Indian Ocean exhibits strong variability on a number of time scales, including prominent intraseasonal variations in both the atmosphere and ocean. Of particular interest is the south tropical Indian Ocean thermocline ridge, a region located between 12° and 5°S, which exhibits prominent variability in sea surface temperature (SST) due to dominant winds that raise the thermocline and shoal the mixed layer. In this paper, submonthly (less than 30 day) cooling events in the thermocline ridge region are diagnosed with observations and models, and are related to large-scale conditions in the Indo-Pacific region. Observations from the Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) satellite were used to identify 16 cooling events in the period 1998–2007, which on average cannot be fully accounted for by air–sea enthalpy fluxes. Analysis of observations and a hierarchy of models, including two coupled global climate models (GFDL CM2.1 and GFDL CM2.4), indicates that ocean dynamical changes are important to the cooling events. For extreme cooling events (above 2.5 standard deviations), air–sea enthalpy fluxes account for approximately 50% of the SST signature, and oceanic processes cannot in general be neglected. For weaker cooling events (1.5–2.5 standard deviations), air–sea enthalpy fluxes account for a larger fraction of the SST signature. Furthermore, it is found that cooling events are preconditioned by large-scale, low-frequency changes in the coupled ocean–atmosphere system. When the thermocline is unusually shallow in the thermocline ridge region, cooling events are more likely to occur and are stronger; these large-scale conditions are more (less) likely during La Niña (El Niño/Indian Ocean dipole) events. Strong cooling events are associated with changes in atmospheric convection, which resemble the Madden–Julian oscillation, in both observations and the models.
Geographic Aspects of Temperature and Concentration Feedbacks in the Carbon Budget
Authors: Boer G. J. , Arora V.
Published: September 2009

The geographical distribution of feedback processes in the carbon budget is investigated in a manner that parallels that for climate feedback/sensitivity in the energy budget. Simulations for a range of emission scenarios, made with the Canadian Centre for Climate Modelling and Analysis (CCCma) earth system model (CanESM1), are the basis of the analysis. Anthropogenic CO2 emissions are concentrated in the Northern Hemisphere and provide the forcing for changes to the atmospheric carbon budget. Transports redistribute the emitted CO2 globally where local feedback processes act to enhance (positive feedback) or suppress (negative feedback) local CO2 amounts in response to changes in CO2 concentration and temperature.

An increased uptake of CO2 by the land and ocean acts to counteract increased atmospheric CO2 concentrations so that “carbon–concentration” feedbacks are broadly negative over the twenty-first century. Largest values are found over land and particularly in tropical regions where CO2 acts to fertilize plant growth. Extratropical land also takes up CO2 but here the effect is limited by cooler temperatures. Oceans play a lesser negative feedback role with comparatively weak uptake associated with an increase in the atmosphere–ocean CO2 gradient rather than with oceanic biological activity.

The effect of CO2-induced temperature increase is, by contrast, to increase atmospheric CO2 on average and so represents an overall positive “carbon–temperature” feedback. Although the average is positive, local regions of both positive and negative carbon–temperature feedback are seen over land as a consequence of the competition between changes in biological productivity and respiration. Positive carbon–temperature feedback is found over most tropical land while mid–high-latitude land exhibits negative feedback. There are also regions of positive and negative oceanic carbon–temperature feedback in the eastern tropical Pacific.

The geographical patterns of carbon–concentration and carbon–temperature feedbacks are comparatively robust across the range of emission scenarios used, although their magnitudes are somewhat less robust and scale nonlinearly as a consequence of the large CO2 concentration changes engendered by the scenarios. The feedback patterns deduced nevertheless serve to illustrate the localized carbon feedback processes in the climate system.
Application of the Priestley–Taylor Approach in a Two-Source Surface Energy Balance Model
Authors: Agam Nurit , Kustas William P. , Anderson Martha C. , Norman John M. , Colaizzi Paul D. , Howell Terry A. , Prueger John H. , Meyers Tilden P. , Wilson Tim B.
Published: September 2009

The Priestley–Taylor (PT) approximation for computing evapotranspiration was initially developed for conditions of a horizontally uniform saturated surface sufficiently extended to obviate any significant advection of energy. Nevertheless, the PT approach has been effectively implemented within the framework of a thermal-based two-source model (TSM) of the surface energy balance, yielding reasonable latent heat flux estimates over a range in vegetative cover and climate conditions. In the TSM, however, the PT approach is applied only to the canopy component of the latent heat flux, which may behave more conservatively than the bulk (soil + canopy) system. The objective of this research is to investigate the response of the canopy and bulk PT parameters to varying leaf area index (LAI) and vapor pressure deficit (VPD) in both natural and agricultural vegetated systems, to better understand the utility and limitations of this approximation within the context of the TSM. Micrometeorological flux measurements collected at multiple sites under a wide range of atmospheric conditions were used to implement an optimization scheme, assessing the value of the PT parameter for best performance of the TSM. Overall, the findings suggest that within the context of the TSM, the optimal canopy PT coefficient for agricultural crops appears to have a fairly conservative value of ∼1.2 except when under very high vapor pressure deficit (VPD) conditions, when its value increases. For natural vegetation (primarily grasslands), the optimal canopy PT coefficient assumed lower values on average (∼0.9) and dropped even further at high values of VPD. This analysis provides some insight as to why the PT approach, initially developed for regional estimates of potential evapotranspiration, can be used successfully in the TSM scheme to yield reliable heat flux estimates over a variety of land cover types.
Idealized Two-Dimensional Modeling of a Coastal Buoyancy Front, or River Plume, under Downwelling-Favorable Wind Forcing with Application to the Alaska Coastal Current
Authors: Williams William J. , Weingartner Thomas J. , Hermann Albert J.
Published: September 2009

The cross-shelf structure of a buoyancy-driven coastal current, such as produced by a river plume, is modeled in a two-dimensional cross-shelf slice as a “wide” geostrophically balanced buoyancy front. Downwelling-favorable wind stress applied to this front leads to advection in the surface and bottom boundary layers that causes the front to become steeper so that it eventually reaches a steep quasi-steady state. This final state is either convecting, stable and steady, or stable and oscillatory depending on D/δ* and by /f 2, where D is bottom depth, δ* is an Ekman depth, by is the cross-shelf buoyancy gradient, and f is the Coriolis parameter. Descriptions of the cross-shelf circulation patterns are given and a scaling is presented for the isopycnal slope. The results potentially apply to the Alaska Coastal Current, which experiences strong, persistent downwelling-favorable wind stress during winter, but also likely have application to river plumes subjected to downwelling-favorable wind stress.
Airborne Doppler Lidar Investigation of Sea Surface Reflectance at a 355-nm Ultraviolet Wavelength
Authors: Li Zhigang , Lemmerz Christian , Paffrath Ulrike , Reitebuch Oliver , Witschas Benjamin
Published: September 2009

The analysis of the sea surface reflectance for different incidence angles based on observations of an airborne Doppler lidar at an ultraviolet wavelength of 355 nm is described. The results were compared to sea surface reflectance models, including the contribution from whitecaps, specular reflection, and the subsurface volume backscattering. The observations show the expected effect of the wind stress on the sea surface reflectance and allow new insights into the significant contribution from subsurface reflectance for large incidence angles. While most of the observations and model results were obtained for isotropic reflectance, first results on anisotropic reflectance are also provided. The results from this study are relevant to future spaceborne wind lidar instruments, for example, the Atmospheric Dynamics Mission (ADM)-Aeolus, which could use the sea surface reflectance for the calibration of intensity and wind.
Formation and characterisations of S phase in plasma carburised high carbon Stellite 21 CoCr alloy
Authors: Chen J. , Li X. Y. , Dong H.
Published: September 2009

Our recent work has revealed that a hardened layer ( H≈13 GPa, E≈230 GPa) with combined improvements in wear and corrosion resistance can be formed on CoCr alloys during plasma surface alloying with carbon. However, the formation mechanism cannot be explained based on current S phase theory for austenitic stainless steels as CoCr alloys normally have a dual phase (fcc and hcp) structure at room temperature. Hence, the present research is directed at advancing scientific understanding of the hardened S phase layers formed in high carbon cast Stellite 21 CoCr alloy. Detailed characterisation has been conducted by glow discharge spectrometry, XRD, SEM/EDX, TEM and nano-indentation. Results have revealed that while the as received Stellite 21 alloy is mainly composed of fcc and hcp phases, the extremely hard surface layer formed on the CoCr alloy during low temperature plasma carburising consists of a carbon supersaturated fcc structured phase, i.e. an S phase, with numerous entangled dislocations and stacking faults. The formation of the S phase could be attributed to the high capability of carbon in stabilising the γ phase and the paraequilibrium nature of the low temperature plasma carburising processes.
Fabrication of porous Al alloy coatings by cold gas dynamic spray process
Authors: Lee H. , Ko K.
Published: September 2009

Al alloy coatings (Al–Mg binary) were prepared by cold gas dynamic spray and characteristics of the porous Al alloy coatings were examined after post-annealing. The coatings of composites (Al–Mg and Al–AlMg) were annealed in a nitrogen atmosphere for four hours. Post-annealing caused Mg in the coatings to diffuse into the Al matrix by eutectic reaction between Al and Mg. For Al/AlMg multicoatings, porous layers in the coatings were formed by post-annealing (diffusion of Mg into the Al matrix). Therefore, processing parameters such as particles and coating method can be used for controlling the size and distribution of pores in cold sprayed coatings.
Synthesis of 4H-Cyclopenta[def]phenanthrene from 1-Naphthylacetic Acid
Authors: Kim Jinwoo , Jin Youngeup , Song Suhee , Kim Il , Suh Hongsuk
Published: September 2009

4H-cyclopenta[def]phenanthrene (CPP) was prepared from 1-naphthylacetic acid in six steps with an overall yield of 36%. From easily available ethyl 1-naphthaleneacetate, the Michael addition and Lewis acid catalyzed dicyclization provided the diketone, which was reduced and dehydrated to give CPP.
Ni–Al Layered Double Hydroxide Prepared by Liquid Phase Deposition
Authors: Mizuhata Minoru , Hosokawa Akinobu , Béléké Alexis Bienvenu , Deki Shigehito
Published: September 2009

Al-containing nickel layered double hydroxide was prepared by liquid phase deposition (LPD) using aluminum metal or compounds as the fluorine scavenger in the equilibrium reaction of nickel–fluorine complex ion. The obtained phases depend on the Al content when it is solely used as F− scavenger; α-nickel hydroxide is the predominant phase and a small amount of β-phase is detected. In contrast pure Ni–Al LDH/C composites, isostructural and isomorphic to α-Ni(OH)2 are obtained at any range of Al content from 0 to ca. 30 mol % of [Al]⁄[Al+Ni]. High stability of LDH in 6 M aqueous KOH solution was performed because of low impurity of cation species.
Reductive Self-coupling Reaction of Imines and Aldehydes Induced by Strontium Metal
Authors: Miyoshi Norikazu , Kohno Tadashi , Wada Makoto , Matsunaga Sei , Mizota Isao , Shimizu Makoto
Published: September 2009

Aromatic aldimines reacted with Sr in the presence of a catalytic amount of iodine to give self-coupling products in good yields, whereas aromatic and aliphatic aldehydes underwent a similar reaction effected by the combined use of Sr and Al(OEt)3.
Synthesis of Polysilanes by Tunneling Reactions of H Atoms with Solid Si2H6 at 10 K
Authors: Sogoshi Norihito , Sato Shoji , Takashima Hideaki , Sato Tetsuya , Hiraoka Kenzo
Published: September 2009

Tunneling reactions of H atoms with solid Si2H6 at 10 K were investigated. The in situ and real-time reactions H + Si2H6 to form silane and polysilanes were monitored using FT-IR. Quantitative analysis of gaseous products was made by thermal desorption spectrometry. Monosilane and polysilanes were detected as major reaction products. The intermediate product SiH2 was suggested to play an important role for the growth of the Si–Si network of the solid products.
Applications of Emission Spectroscopy to Trace Element Analysis in Plant and Soil Samples
Authors: Schrenk WG
Published: September 2009

This paper describes spectrographic procedures which have been of use in agricultural research. Included has been a discussion of the approach used to design satisfactory analytical procedures and a description of some of the problems in which these methods have been used.

The use of spectrographic techniques in agriculture is not new, neither is it limited in scope. In fact, this approach is used all over the world where problems of this nature are studied. It is regretted that all such work cannot be acknowledged in a paper such as this. As the field of analytical spectroscopy continues to grow and develop, it may be expected that workers in agriculture will continue to take advantage of the methods of spectroscopy to help solve problems that would be extremely difficult, if not impossible, to study by other methods.
Spectrochemical Analysis for Trace Elements in Geological Materials
Authors: Murata KJ
Published: September 2009

Because 99 per cent of the earth's crust consists of only ten elements, all with atomic numbers smaller than 27, the vast majority of the elements are trace constituents of the crust. Semiquantitative and quantitative spectrochemical methods are being used extensively in basic gcochemical studies on the distribution of the elements in crystal rocks, in systematic exploration for hidden ore deposits, and in determination of by-product elements in ores. Trace analysis of natural crystals is of interest with respect to structure-sensitive properties such as color and fluorescence. Trace elements in river and ocean waters constitute a challenging subject for research.
Standard Toxicity Evaluation of Chemicals Poisonous to the Marine Borer
Authors: Vind Harold , Hochman Harry
Published: September 2009

Many investigators have studied the toxicity of chemical agents to wood-destroying organisms, but the majority of the investigators have been concerned only with wood-destroying fungi. In general, those who have studied the toxicity of chemical agents to marine borers have considered rapid kill rather than low concentration to be the criterion of high potency.
Prediction of Acoustic Fatigue Life
Authors: Schjelderup H. C.
Published: September 2009

Current procedures used by the airframe industry for predicting fatigue life of structures loaded by high-energy acoustical noise are reviewed. Deficiences in the methods are discussed and future work is suggested. The need for spectrum-type fatigue tests is emphasized.
Viscometry of Polymer Solutions in a Coaxial-Cylinder Viscometer under High Rates of Shear
Authors: Merrill Edward W.
Published: September 2009

The design and operation of a coaxial-cylinder viscometer that permits measurements over a range of shear rate up to 96,000 reciprocal seconds are described. Principal design features are: stator cylinder mounting on an air bearing; circulation of temperature-controlling liquid through both rotor and stator; narrow annular width (0.15 mm); automatic programing of shear rate as a function of time; and automatic recording of shear stress versus shear rate, or shear stress versus time of shear at constant shear rate. A resume of experimental results on various polymer solutions is given.
ASTM Investigation of Low-Temperature Viscometry of Engine Oils
Authors: Selby Theodore W.
Published: September 2009

This paper constitutes a report by the chairman of Section B, Research Division VII on Flow Properties of ASTM Committee D-2 on Petroleum Products and Lubricants, on the activities of Section B in the field of engine oil viscometry at low temperatures.

In presenting this report, the chairman presumes to summarize the information thus far presented, privately or publicly, by members or associates of Section B. While this report may not completely reflect the views of all contributors, it is hoped that it correctly amalgamates their work into an easily accessible, and generally useful, body of information on the subject.

The members and associates of Section B contributing to the work in the area of high-shear viscometry of engine oils at low temperatures are: O. L. Brandes, Member, of the Gulf Research and Development Co., A. W. Sisko, Associate, who contributed to the effort through L. C. Brunstrum, Member, both of the Standard Oil Co. of Indiana, G. A. Kohl and R. D. Skoglund, Associates, who contributed their work through J. R. Callaway, Member, all of the Texaco Research Laboratories, E. O. Forster, Associate, who contributed a portion of the total effort submitted by H. H. Horowitz, Member, both of the Esso Research and Engineering Co., E. W. Merrill, Member, of the Massachusetts Institute of Technology, M. J. Pohorilla, Member, of the Kendall Refining Co., and T. W. Selby, Member, of the General Motors Research Laboratories.
Comparison of In-Reactor Creep and Postirradiation Creep Tests of Structural Materials for Nuclear Applications
Authors: Gilbert E. R. , Harding N. E.
Published: September 2009

Neutron irradiation can cause the creep rate of a material to increase, decrease, or to remain unchanged. Each of these possible results has been observed in creep during neutron irradiation. In hep alloys increased creep rates have been observed both in Zircaloy-2 and Zr-2.5Nb at creep rates below 10-10 sec-1 at 300 C. At temperatures above 350 C in-reactor creep rates of Zr-2.5Nb are no different from those of unirradiated control tests, whereas in Zircaloy-2 the creep rate may increase, decrease, or remain the same on reactor shutdown, depending on the stress and temperature. Stress relaxation tests reported for zirconium alloys below 100 C resulted in more relaxation during neutron irradiation, suggesting faster creep rates.

In-reactor creep tests for fcc alloys Type 304 stainless steel and Hastelloy X-280 at temperatures above 500 C have resulted in little if any difference in creep rate, although the range of second-stage creep was significantly reduced. Faster in-reactor creep rates are inferred for nickel, copper, and 18-8 stainless steel through greater stress relaxation during neutron irradiation below 100 C.
Irradiation-Induced Embrittlement in Stainless Steel at Elevated Temperature
Authors: Kangilaski M. , Perrin J. S. , Wullaert R. A.
Published: September 2009

Type 347 stainless steel was found to undergo extreme embrittlement above 550 C after irradiation to a fast fluence of 2.1 × 1022 n/cm2. This embrittlement could not be removed by annealing at 980 C, although the anneal restored the preirradiation tensile properties at temperatures up to 500 C. The long-time irradiation was found to cause significant increases in copper, vanadium, and zinc contents while the manganese content was decreased. It is suggested that segregation of these solid transmutation products to the grain boundaries may prevent grain boundary migration during tension testing at elevated temperatures. Prevention of grain boundary migration during testing may enhance the ductility minimum present in most alloys at intermediate testing temperatures.
Notch Ductility, Tensile and Neutron Spectrum Analyses of PM-2A Reactor Pressure Vessel
Authors: Serpan C. Z. , Watson H. E.
Published: September 2009

Following the pressurization-to-failure testing of the PM-2A reactor pressure vessel, several sections of steel were removed from the vessel wall in a region adjacent to the artificial defect. Charpy V-notch and tension test specimens machined from one of these sections were evaluated. The irradiated-condition 30 ft-lb transition temperatures for the 1/4 thickness (nearest to the core) and 3/4 thickness locations in the vessel wall were +115 and +55 F, respectively, for measured fission spectrum fluences of 7.3 and 4.0 × 1018 n/cm2 ⟩1 MeV. The 1/4 thickness properties and fluence most nearly represented those at the tip of the artificial defect. The 0.2 percent yield strength for the 1/4 thickness location was 97,620 psi at -20 F (failure temperature) and 92,200 psi at +72 F (temperature at time of acid sharpening treatment of artificial defect). Significant uniform elongation, reduction of area, and elongation in 1 in. were retained by the steel. An assessment of the stress, temperature, and flaw size conditions for the PM-2A failure, as indexed by the irradiated-condition mechanical properties, indicates that the failure is in agreement with the generalized fracture analysis diagram.
The Effect of Substructure on the Biaxial Strength and Irradiation Stability of ASTM A 302 Grade B Steel
Authors: Flynn P. W. , Trozera T. A.
Published: September 2009

ASTM Specification A 302 Grade B steel was given thermal-mechanical treatments to improve mechanical properties through development of substructure. Cold work of 0.06 followed by a 435 C heat treatment produced a 28,000 psi (35 percent) increase in lower yield strength without loss of uniform elongation. Specimens were irradiated at <100 C and 288 C to fast fluences in the range of 1 × 1018 to 5.2 × 1019 n/cnr. Standard tension tests, biaxial stress (tube) tests, and instrumented Charpy-V impact tests were performed.

Data from the biaxial tests were analyzed on the basis of uniform strain predicted from the uniaxial (simple tension) test. A mathematical analysis of the instability criteria is included. Data from the Charpy tests were analyzed to determine (1) the relation between substructure and irradiation response in terms of the nil ductility transition temperature shift and (2) the way in which the sample breaking energy is distributed between crack initiation and propagation. Major conclusions from these analyses are: The predicted instability strain in the biaxial test is not exceeded. A constant cell size (and degree of substructure) is reached at small amounts of cold work and does not appear to be exceeded. An appropriate substructure treatment may decrease radiation sensitivity and may increase energy absorption in fracture propagation in the Charpy test.
Effects of Interstitial Elements on Radiation Hardening in Mild Steels
Authors: Little E. A. , Harries D. R.
Published: September 2009

Neutron irradiation produces greater increases in room-temperature tensile lower yield stress of annealed silicon killed mild steel than in that of annealed aluminum grain size controlled steel. This difference in behavior is due primarily to the presence of free nitrogen in the silicon-killed steel. Preliminary results suggest that free carbon in the steels does not enhance the radiation hardening.

The amount of nitrogen in solution in the silicon killed mild steel is progressively reduced with increasing neutron dose. Furthermore, the nitrogen returns to solution and the radiation hardening is recovered on annealing at temperatures in the range 300 to 400 C.

These effects are attributed to the nitrogen and the irradiation-induced point defects forming complexes that restrict dislocation movement and thereby increase the radiation hardening.

Neutron irradiation has a marked effect on the dynamic strain ageing behavior and the temperature dependence of the yield and flow stresses of the annealed silicon killed mild steel in the range 90 to 250 C. The results are explained on the basis of a strain rate effect, assuming that channeling is the operative deformation mechanism in the irradiated steel, and thermal activation of the radiation damage.
Radiation Hardening and Embrittlement in a Reactor Pressure Vessel Steel
Authors: Wechsler M. S. , Berggreen R. G. , Hinkle N. E. , Stelzman W. J.
Published: September 2009

The relationship between the increase in tensile yield stress (YS) and the increase in the ductile-brittle transition temperature (DBTT) upon irradiation was studied for ASTM A 212-65 Grade B pressure vessel steel. Smooth tension specimens and Charpy V-notch impact specimens were irradiated in the same facility of the Oak Ridge Research Reactor under the same conditions of 60 C irradiation temperature and 1 × 1010 neutrons/cm2 (E > 1 MeV) fluence. The tension tests were carried out at temperatures from 20 to 473 K at two strain rates. The YS increased rapidly with decreasing test temperature, but the radiation-produced increment in YS was largely independent of test temperature. The impact specimens also were tested as a function of temperature and the increase in DBTT was determined based on absorbed energy and fracture appearance. To correlate the changes in YS and DBTT upon irradiation, strain-rate and triaxiality corrections were applied to the tensile yield stresses to approximate the corresponding stresses at the root of the notch of the impact specimens. The results of the tension and impact tests were found to be consistent, based on a critical cleavage stress deduced from the tension tests. No evidence for a decrease in the critical cleavage stress upon irradiation was noted.

The conclusion is that the radiation embrittlement is largely a consequence of radiation hardening and not a change in fracture properties as such.
Development of a Titanium-Modified Hastelloy N with Improved Resistance to Radiation Damage
Authors: McCoy H. E. , Weir J. R.
Published: September 2009

Our studies of the effects of neutron irradiation on the hightemperature mechanical properties of Hastelloy N have shown generally that the creep-rupture life and ductility are reduced. The ductility is a strong function of the strain rate and shows a minimum at a minimum creep rate of about 0.1 percent per hour.

The resistance of this material to radiation damage can be enhanced greatly by adding titanium. Laboratory and commercial melts have shown that the postirradiation creep-rupture ductility and strength rise sharply as the titanium content is increased above 0.3 weight percent. Although the degree of improvement is still rising as the titanium level is increased to 1 percent, most of our studies have been carried out on an alloy with about 0.5 weight percent titanium. Postirradiation creep-rupture tests at 650 C on specimens irradiated to a thermal fluence of 5 X 1020 neutrons cm2 indicate that a ductility minimum still exists as a function of strain rate. However, the minimum strain is 3 to 5 percent as compared with 0.5 percent for the standard alloy. In-reactor creep-rupture tests have also been run and the same improved properties are indicated.

Our studies of the titanium-modified alloy have not progressed sufficiently to pinpoint the exact role of titanium in bringing about the improved properties. However, several observations have been made which allow us to make some postulations at this time.
Multiaxial In-Reactor Stress-Rupture Strength of Stainless Steels and a Nickel Alloy
Authors: Laue H. J. , Böhm H. , Hauck H.
Published: September 2009

In the framework of the cladding program for fast breeders we have tested the behavior of tubes under constant pressure during irradiation. The test facility and the type of specimens are described briefly.

The maximum available helium pressure was 500 atm and the test temperature between 600 and 700 C. Tests were run with the stainless steels, 16Cr-13Ni, 20Cr-25Ni, and Incoloy 800, and a nickel alloy, Inconel 625. The irradiation was done in the BR2 reactor at Mol, Belgium, with a fast neutron flux of 2 to 4 × 1014 n/cm2 s and a maximum time-to-rupture of 3000 h. Identical tests were done without irradiation, and the results were as follows: 16Cr-13Ni—The decrease of the stress-rupture strength under irradiation was in the range of 40 to 50 percent and the absolute tangential strain between 0.4 and 1.0 percent. Inconel 625—The comparison of different types of unirradiated specimens showed the influence of the specimen dimensions and test conditions. The stress-rupture strength of irradiated tubes was decreased by 30 to 40 percent; the corresponding tangential strain was smaller than 1 percent. Incoloy 800—The outstanding result of this alloy was the relatively high tangential strain under irradiation (3.0 to 4.5 percent). The reduction of stress-rupture strength by irradiation was of the same order as for the stainless steel. 20Cr-25Ni—The reduction of strength upon irradiation was in the range of 30 percent, and the tangential strain was smaller than 1 percent. The rupture time at a load of 9.5 kg/mm 2 at 600 C was only 2500 h.

The metallographic tests of all the irradiated specimens have shown in each case small intergranular cracks and no burst. The results are discussed and conclusions are reached concerning the optimal fuel-element design.
Vapor Space Inhibited Steam Turbine Oils
Authors: Lurton H M , Rozalsky I , Seelbach C L
Published: September 2009

In steam turbine operation, vapor space rusting can occur on interior metal surfaces not in intimate contact with the turbine oil. In some cases, operating practices can be recommended to reduce the danger of rusting. In other cases, service conditions may make these practices impractical. This has prompted the desire for a turbine oil with built-in vapor space protective properties. Effective vapor space inhibition has been obtained in steam turbine oils by the use of small concentrations of certain relatively low-molecular-weight organic acids. No degradation in pertinent turbine oil properties, for example, ASTM rust tests and demulsibility, is incurred. Laboratory test results have been confirmed by field tests.
Single-Cylinder Test Techniques for Engine Oils—Part Two: Development of CRC L-43 Test Technique
Authors: McLaughlin E. J.
Published: September 2009

One of the most important functions of a gasoline engine crankcase lubricant is adequate control of the formation of varnish and sludge deposits in engines in service. Measuring or predicting the ability of lubricants to perform this function, based on laboratory tests, is very difficult because of the many types of engines in service use and, for each given engine, many different types of operating conditions. Most of the individual engineering departments of the major American automotive and petroleum companies have developed for their own use a wide variety of laboratory tests for this purpose. In 1958 the Program and Analysis Panel of the CRC Motor Engine Varnish and Sludge Group formed a sub-panel having the assignment of preparing a program aimed at the development of a test technique employing the singlecylinder Cooperative Lubricant Research (CLR) oil test engine which would give the desired correlation with varnish and sludge ratings in field service. This project was supported by the voluntary participation of over 20 laboratories which contributed generously in both man-hours and engine operating time. The L-43 technique described here resulted from this effort. However, the work is not complete; and additional programs are being planned by the participants in this cooperative work. Considerable additional effort will be required before a suitable technique that satisfies the objectives of the program is developed.
Where Do We Go From Here in Motor Oil Testing?
Authors: McReynolds L. A.
Published: September 2009

A specially appointed group of the Coordinating Research Council (CRC) has considered the future of motor oil testing. While the currently published MS (most severe) sequence tests establish a language which is generally satisfactory for defining problems in current engines, the CRC group concluded that future efforts should be directed toward more precise and enduring tests using the CLR Oil Test Engine and selected reference fluids.
Some Technical Aspects of the Motor Oils Market in France and in Europe
Authors: Thiery J.
Published: September 2009

This paper evaluates the requirements of crankcase lubricants for France and Europe by reviewing current automotive practices.

The present status of motor oil consumption for both gasoline and diesel engines is examined for France and other European countries, and future developments of engine oils are discussed.

The specific requirements for diesel and gasoline engines currently produced in Europe are listed. In this field there are some marked differences from corresponding U.S. engines and these are reviewed.

The user's situation as regards the lubricating requirements of automcbiles now being operated in France and Western Europe are discussed, and the extent to which the producers of lubricating oil can satisfy these needs is reviewed.

The paper presents a forecast on engines and lubricant developments, and the possible impact of the Common Market.
Changes in Properties of Plastics During Implantation
Authors: Leininger R. I.
Published: September 2009

The literature for the last eight years was surveyed for information as to the change in properties of plastics caused by implantation. It was found that comparatively little work has been done. Plastics whose change in properties have been measured include nylon, Orlon, Dacron, Teflon, polyethylene, Silastic, polyurethane, and Mylar. Based on the few results available, Dacron and Silastic show the least change in periods up to a year and a half.
Studies On Polymer Implants In Humans
Authors: Johnson F. B.
Published: September 2009

The clinical, gross and microscopic findings in cases of plastic implantation in humans for vascular prosthesis and for plastic surgery have been reviewed. Reactions to the following materials are included: Cellophane, Dacron, Nylon, Orlon, polyethylene, and Teflon. The plastic implants are associated with varying intensities of inflammatory reaction and fibrosis. The principal causes of functional failure are thrombosis, hemorrhage, and excessive fibrosis. At times the hemorrhage can be shown to be due to fragmentation of the plastic with loss of mechanical integrity. No specific or characteristic inflammatory lesions were found to be due to any particular plastic. None of the tissues showed evidence of malignant changes.
In-Reactor Creep of Zirconium-Alloy Tubes and Its Correlation with Uniaxial Data
Authors: Ibrahim E. F.
Published: September 2009

A creep experiment on 23-mm diameter tubular specimens of Zircaloy-2 is described. The specimens are stressed biaxially at hoop stresses from 11 to 26 kgf/mm2 at 260 C at three neutron flux conditions. The results confirm that fast neutrons increase creep rates at all the stresses tested, but thermal neutrons have no detectable effect. The creep data are consistent with those obtained on larger tubes.

A method is described for correlating biaxial tubular and uniaxial in-reactor creep results for zirconium alloys and this is applied to cold-worked Zircaloy-2, cold-worked 2.5Nb zirconium, and heat-treated 2.5Nb zirconium alloys.
Texture Changes Produced During Zircaloy-4 Tubing Fabrication: From Forged Billet to Finished Tubing
Authors: Hobson D. O.
Published: September 2009

Certain fabrication procedures yield tubing with large variations in texture around the circumference. Such variations lead to non-uniform mechanical properties and to difficulties in design specifications. The purpose of this work was to follow the texture changes that occur during fabrication from forged billet through extrusion, rocking, and straightening to finished tubing and to determine the effects various fabrication schedules have on the textures of the tubing.

We observed the development of texture inhomogeneities at each step of tubing fabrication.

The significance of this work is that, for the first time, a detailed texture study has been made through an entire set of tubing-fabrication runs under controlled conditions of starting stock, tubing reductions, and heat treatment. Such an examination yields valuable insight into the causes of varying texture quality in tubing.
Corrosion and Failure Characteristics of Zirconium Alloys in High-Pressure Steam in the Temperature Range 400 to 500 C
Authors: Johnson A. B.
Published: September 2009

A nuclear fuel-failure phenomenon prompted a study of the corrosion properties of the Zircaloy-2 fuel cladding. The principal studies were conducted at 400, 450, 475, and 500 C in steam at 1700 psig. Materials tested were: five lots of Zircaloy-2; one lot of Ozhennite (Zr-0.2Sn-0.1Fe-0.1Ni-0.1Nb); and one lot of crystal bar zirconium. As-fabricated (rolled or extruded) Zircaloy-2 underwent a rapid approach to failure in tests at 475 and 500 C. The attack involved nucleation of nodular oxide which spread across the surface, finally resulting in an accelerated, relatively uniform attack. Ozhennite was resistant to the attack. Heat treatments (α and β anneals) delayed the catastrophic attack on Zircaloy-2 but not on crystal bar zirconium.
Effects of Nuclear Radiation on the Corrosion, Hydriding, and Oxide Properties of Six Zirconium Alloys
Authors: Johnson A. B.
Published: September 2009

A series of in-reactor corrosion tests was conducted in the G-7 loop of the Engineering Test Reactor (ETR) in pH 10 NH4OH at 270 to 280 C. Six zirconium alloys were exposed in as-etched and prefilmed (400 C steam) surface conditions. The six alloys were Zircaloy-2, Zircaloy-4, Zr-3Nb-1Sn, Zr-2.5Nb, Zr-1.2Cu-0.28Fe, and Zr-1.2Cr-0.08Fe. Exposures were 25, 37, 77, and 174 days in high-flux, low-flux, out-of-flux, and out-of-reactor environments. Results from the 174-day exposure are emphasized, but corrosion and hydriding data from the complete test series are compared.

A marked upturn in corrosion rate between the 77- and 174-day exposures is attributed to an increase in oxygen level near the end of a deoxygenating resin life. In the 174-day experiment, corrosion rates were accelerated on the six alloys at the high-flux position, but only on Zr-Cr-Fe specimens at the low-flux position. Prefilming adversely affected the corrosion of Zr-Cr-Fe, Zr-Cu-Fe, Zircaloy-2, and Zircaloy-4 specimens. The alloys containing niobium were the most resistant to in-flux corrosion and hybriding. Hydrogen-absorption rates were generally proportional to corrosion rates.

Monoclinic zirconium oxide was the principal phase on high-fluence (1.7 × 1021, n/cm2, > 1 MeV) specimens of the six alloys. Non-uniform oxidation was observed on Zr-Cr-Fe and Zr-2.5Nb alloys, including pustules, pitting, and cracks. Banded chromium segregation was observed in a Zr-Cr-Fe oxide and nodular copper segregation was observed in a Zr-Cu-Fe oxide; niobium distribution was relatively uniform in a Zr-2.5Nb specimen.
The Use of Hydrogen Getters for Prevention of Hydrogen Embrittlement in Zirconium-Alloy Fuel Cans
Authors: Spalthoff W. , Wilhelm H.
Published: September 2009

For prevention of hydrogen embrittlement in zirconium-alloy fuel cans it is proposed to insert yttrium as a hydrogen getter inside the fuel can. An evaluation of hydrogen decomposition-pressure measurements of all metal hydrides at question shows that in the range 300 to 500 C, yttrium has the highest affinity to hydrogen. At 300 C the hydrogen in yttrium dihydride is in equilibrium with 1 ppm per weight of hydrogen solved in alpha-phase zirconium. These calculations so far are confirmed by diffusion and corrosion experiments.