bluuebunny/crossref_metadata_2025 huggingface dataset:
Round-Robin Tests on Test Cells for Insulating Gases
Authors: Liao T. W. , Shombert G.
Published: September 2009

A round-robin test of the three existing test cells for the determination of dielectric strength of gases was conducted by Section VI of the Electrical Tests Subcommittee N of ASTM Committee D-27 on Electrical Insulating Liquids and Gases. Eleven laboratories participated. This is the initial step in the development of an ASTM test cell for testing the dielectric strength of gases. The test cells are basically similar, each consisting of sphere and plane electrodes enclosed in a glass cylinder with the necessary fittings for gas-tight construction. Nitrogen and sulfur hexafluoride gases were tested under specified test conditions and methods. The test results were analyzed statistically. They indicate that the basic construction of the cells and the test methods are sound because there is no indication that the cells differ with respect to variability of the results obtained. The analyses also suggest some room for improvement.
The Isolation, Separation, and Identification of Microconstituents in Steels
Authors: Andrews K. W. , Hughes H.
Published: September 2009

A general scheme relating the chemical and instrumental methods available for isolation and identification of microconstituents in steel is presented. Several techniques are discussed in more detail. These include electrolytic solution, selective centrifuging, and use of the petrological microscope. High-silica values were obtained when thiocyanate and citrate were used as electrolytes in electrolyses of the Klinger and Koch type. The anomalous values were traced to oxidation of silica in the steel to silicic acid. Washing the residue with sodium carbonate eliminated this problem. The authors describe use of a potentiostat for selective solution of complex austenitic 15Cr-25Ni steels containing additions of other metals. Use of the threshold centrifuge to separate residues by weight and size for X-ray diffraction analysis is discussed. An example of identification of spinels in a globular silicate inclusion by the petrological microscope is also presented. Throughout the paper the complementary nature of the various methods and the use of methods in combination are stressed.
Application of Differential Thermal Analysis-Effluent Gas Analysis to the Determination of Nonmetallic Compounds in Steel
Authors: Bandi M. R. , Straub W. A. , Karp H. S. , Melnick L. M.
Published: September 2009

Preliminary studies indicate that differential thermal analysis — effluent gas analysis (DTA-EGA) may find practical application in analysis of compounds present in inclusions separated from steel. In this type of differential thermal analysis, a dynamic atmosphere is used. Gaseous products of a reaction in which there is a heat content change are analyzed, generally by thermal conductivity, although the use of gas chromatography and coulometry also are discussed. From the temperature at which reaction occurs the compound can be identified, and from analysis of a gaseous product, the amount of the compound present can be determined. Calibration with carbon dioxide (CO2) evolved from calsium carbonate indicates that metal carbides may be determined with an accuracy of about 15 per cent. DTA — EGA curves are presented for titanium carbide and zirconium carbide reacting with a dynamic oxygen atmosphere to produce the oxide and CO2 and for the titanium inclusions separated from 6 low alloy steel specimens in which carbon, nitrogen, and sulfur contents were varied.
Identification of Inclusions with the Electron Probe Microanalyzer
Authors: Heinrich K. F.J.
Published: September 2009

Direct identification of the components of inclusions and precipitates can be performed with the aid of the electron probe micro-analyzer. Although the method is restrictive as to minimum particle size, range of detectable elements, and attainable accuracy, satisfactory characterization of the inclusions is generally possible. Special techniques applicable to inclusions and precipitates and recent applications are discussed.
Plane Strain Crack Toughness Testing of High Strength Metallic Materials
Authors: Brown William F. , Srawley John E.
Published: September 2009

This report deals with the design and testing of crack-notched specimens for determination of the resistance of high strength metallic materials to unstable opening-mode crack extension under plane strain conditions. Test methods concerned with subcritical crack extension due to repeated loading or aggressive environments are not discussed. It is assumed that the reader will be familiar with the terminology and concepts of linear elastic fracture mechanics used in earlier reports of ASTM Committee E-24 on Fracture Testing of Metals [1–5]. Much of the background has been thoroughly reviewed recently [6].
Measurement of the Fiber-Polymer Matrix Interfacial Strength
Authors: Broutman L J
Published: September 2009

Although many test specimens have been developed to measure fiber-matrix interfacial strength, they typically suffer from a lack of reproducibility and produce data with coefficients of variation greater than 10 percent. This paper reviews methods thus far employed to evaluate fiber-matrix interfacial strengths including correlation of data from the various test methods.

The stress distribution at a fiber-matrix interface subjected to loading must be known if one is to calculate interfacial fracture stresses due to external load application. Thermal residual stresses due to elevated curing temperature of polymer specimens also must be considered. Equations to predict the shear stresses at fiber ends and the radial and tangential stresses around the interface will be presented. Experimental photelastic determinations of internal stresses will be compared with the theoretical predictions.

Experimental techniques for measuring interfacial strengths for single fibers will be discussed. Examples of strength measurements for glass and boron fibers embedded in polymer matrices will be presented. These strengths have been measured as a function of the specific nature of the interface to evaluate the role of a fiber surface treatment in enhancing this interface strength. The fiber or rod bond strength specimens usually consist of a single embedded fiber or partially embedded rod in a polymer matrix which is failed by loading the matrix in the first case or by loading the rod in the latter case.

Interfacial tensile strengths can be measured using a curved neck specimen, and shear bond strengths can be measured most effectively by a fiber embedded totally within a rectangular bar. A compression load is applied parallel to the fiber axis. A technique related to determination of interfacial toughness of joints by a double cantilever cleavage bar will be discussed and the results compared to strength measurements of similar systems. Finally, measurements on actual fiber composites (horizontal shear strength) will be discussed as a means of measuring fiber-matrix interfacial strength.
Theoretical Studies of the Mechanics of the Fiber-Matrix Interface in Composites
Authors: Greszczuk L B
Published: September 2009

This paper treats the development of pertinent theories that establish the properties of the fiber-matrix interface needed to achieve efficient composites and the development of a test technique to measure these properties. An equation is derived that relates the externally applied load to the failure mode, fiber tensile strength, and interface shear strength. This equation makes it possible to establish the interface strength that is required to obtain overall composite failure instead of interface failure. The effect of interface on the bending stiffness and Young's modulus of filamentary composites is investigated. A technique, based on shear-lag theory, that will measure the properties of the interface is presented. This technique involves pullout tests on fibers that are imbedded in a matrix. An approximate solution also is presented for the shear-stress distribution around a discontinuous fiber that is surrounded by six continuous fibers. The seven fibers are a part of a composite of infinite extent that is subjected to a remotely applied tensile stress. It is shown that there is a significant variation in the shear-stress distribution along the fiber length as well as around its circumference.
Experimental and Analytical Investigation of the Mechanical Behavior of High-Burnup Zircaloy-4 Fuel Cladding
Authors: Daum Robert S. , Majumdar Saurin , Billone Michael C.
Published: September 2009

Sufficient mechanical ductility of high-burnup Zircaloy-4 fuel cladding is important to prevent large-opening ruptures and significant fuel dispersal during postulated in-reactor and spent-fuel processing accidents. The effect of irradiation, oxidation, and hydriding at high fuel burnup may degrade cladding ductility to the extent that such large ruptures are possible under severe loadings. To understand this susceptibility to failure, this study focused on mechanical testing coupled with detailed finite-element modeling and analyses. Under ring-compression-type loading at room temperature, tensile cracks form within the corrosion-induced oxide layer under elastic loading. The oxide crack then propagates into the cladding wall under additional loading with little to no measurable plastic strain, as confirmed by both experiment and analyses of plastic hoop strain in the ring. For cladding with the oxide removed prior to testing at ≤1 %/s, cracking of the underlying hydride rim comprised of circumferentially oriented hydrides occurs at low plastic hoop strain (≤3 %), whereas the finite-element analysis suggests that the base alloy with a relatively small amount of hydrides appears to fail at higher strain (>8 %). At even higher strain rates (≈400 %/s), cracking within the hydride rim occurs at near-zero ductility, but the base alloy continues to remain highly ductile. These room-temperature results indicate that the hydride rim is sensitive to strain rate, whereas the base alloy is relatively not. With the precipitation of ≈100 % radially oriented hydrides, the cladding exhibits near-zero ductility at room temperature and ≈0.1 %/s. This study suggests that the ring-compression test coupled with finite-element modeling and analysis may be used to estimate crack-initiation strains in irradiated cladding materials with susceptible microstructures and under various deformation rates.
Effect of Local Hydride Accumulations on Zircaloy Cladding Mechanical Properties
Authors: Hermann Armin , Yagnik Suresh K. , Gavillet Didier
Published: September 2009

Mechanical response of fuel cladding with local hydride accumulations is crucial in the assessment of cladding integrity at high burn-ups. We have performed high-temperature low-strain rate burst tests on irradiated cladding samples with and without hydride lenses or blisters to seek answers to the following questions: Does the presence of a hydride lens inevitably lead to rupture at a lower pressure? How does it mechanistically affect the crack initiation and propagation? The irradiated samples in our investigation were taken from the regions of the fuel cladding with oxide spallation. Subsequently, we used neutron radiography to further select samples covering a range of hydride blister sizes on which the burst testing was performed. Rupture pressure, hoop strength, and circumferential strain data will be reported. For each sample tested, detailed metallography and fractography were performed on 2-mm size sections containing the burst opening to provide insights into the mechanism of crack initiation and propagation. Local and mean hydrogen concentrations were measured. The paper will include and elucidate new details often not fully investigated by other burst test investigations reported in the open literature. In samples with multiple blisters, the crack initiates at the largest one, which also governs the fracture mode. Reduction in the rupture pressure can be simply correlated to the reduction in sample wall thickness excluding the blister (i.e., its remaining ligament). There is a lower bound on the blister size to have any influence on the rupture pressure. Further, local plastic circumferential strain at each blister can be correlated to relative hydride lens area, as projected onto the cladding surface.
Fracture Toughness of Hydrided Zircaloy-4 Sheet under through-Thickness Crack Growth Conditions
Authors: Raynaud P. A. , Koss D. A. , Motta A. T. , Chan K. S.
Published: September 2009

The susceptibility of fuel cladding to failure in the case of a postulated reactivity-initiated accident may be determined by crack initiation within a hydride blister or rim and subsequent crack growth through the thickness of the cladding. This study has determined the fracture toughness of hydrided cold-worked stress relieved Zircaloy-4 sheet subject to through-thickness crack growth at both 25 and 300°C. The experimental approach utilizes a novel procedure in which a narrow linear strip of brittle hydride blister across the specimen width creates a well-defined precrack upon initial loading. The subsequent crack growth resistance is then characterized by four-point bending of the specimen and an elastic-plastic fracture mechanics analysis. At room temperature, the through-thickness fracture toughness (Kq) is sensitive to the orientation of the hydride platelets and Kq≅25 MPa√m for crack growth through a mixed in-plane/out-of-plane hydride field. In contrast, Kq is much nigher (≅75 MPa√m) when the hydride platelets are oriented predominantly in the plane of the sheet and therefore normal to both the crack plane and the crack growth direction. At 300°C, the material exhibits greater ductility as the hydride particles within the matrix resist fracture such that Kq≅83 MPa√m, despite the much lower flow stress of the material.
Characterization of Local Strain Distribution in Zircaloy-4 and M5® Alloys
Authors: Elbachiri Kamal , Doumalin Pascal , Crépin Jérôme , Bornert Michel , Barberis Pierre , Rebeyrolle Véronique , Bretheau Thierry
Published: September 2009

Zirconium alloys with low alloying content are mainly used in the nuclear industry as structural materials because of their superior properties in terms of neutron transparency, mechanical strength, and corrosion resistance. In order to further improve the corrosion resistance as well as the integrity of Zr based cladding tubes under severe thermomechanical loading, the M5® alloy was developed to replace stress-relieved Zircaloy-4. An experimental study conducted at the macroscopic scale between 20 and 500°C shows that the mechanical behavior of the studied Zr based alloys depends on the metallurgical state (stress-relieved or recrystallized) rather than on the chemical composition. To try to understand these mechanical differences, an experimental multiscale investigation was devised at ambient temperature (20°C) in order to characterize the strain distribution at the scale of the grains and at that of the representative volume element. Local strain fields were measured by means of a microscale digital image correlation technique, based on microgrid deposits and scanning electronic microscopy (SEM). Tensile tests were performed inside the SEM chamber. Here, the original method of strain distribution quantification based on statistical strain field analysis is used. First, this analysis reveals a particular strain distribution consisting of bands with an orientation greater that 45° with regards to the direction of macroscopic tension, and second, shows that these interaction lengths are much greater than the average size of the grains, which clearly demonstrates that local investigations cannot be limited to a few grains. Therefore, the macroscopic mechanical response of these materials is not only governed by intragranular heterogeneities but by the local deformations which become organized between the grains in a pattern of bands at a mesoscale, which is determined by medium to long-range interactions. The difference of values in the band characteristics could partly explain the anisotropic global behavior of these materials linked with their microstructure.
A Study of the Structure and Chemistry in Zircaloy-2 and the Resulting Oxide After High Temperature Corrosion
Authors: Hutchinson Bevis , Lehtinen Börje , Limbäck Magnus , Dahlbäck Mats
Published: September 2009

A plate of Zircaloy-2 received in the β-quenched condition was heat treated to vary systematically the size of the second phase particles (SPPs) and the content of alloying elements retained in solid solution. Scanning electron microscopy and thermoelectric power measurements were used to quantify these microstructural parameters. Specimens were exposed for different periods of time in autoclaves at 415°C and at 500°C in steam, and corrosion was assessed according to the gain in weight. Effects of the microstructure were not great but it was observed that materials having larger SPPs were somewhat more resistant to oxidation in the 415°C tests whereas those with smaller SPPs performed better at 500°C. Influences on corrosion rates that could be attributed to alloy elements in solid solution were small or perhaps nonexistent. The chemistry of oxide layers formed at 500°C has been examined by etching away the zirconium metal and then depth-profiling using sputtered neutral mass spectroscopy. There was some difference in surface topography between the materials with smaller and larger SPPs. The compositional profiles showed that the oxide was substantially under-stoichiometric below the surface in all cases, with O/Zr ratios reaching unity or even less, and extending to depths between 150 nm and 400 nm from the metal oxide interface. These results are discussed in terms of their implication for existence of a diffusional barrier layer and for the stress states that can be expected within the oxide.
Studies of Corrosion of Cladding Materials in Simulated BWR Environment using Impedance Measurements
Authors: Forsberg S. , Ahlberg E. , Limbäch M.
Published: September 2009

In the present work, the corrosion of three Zircaloy-2 cladding materials have been studied in-situ in an autoclave using electrochemical impedance spectroscopy. Measurements were conducted in simulated boiling water reactor environment at temperatures up to 288°C, both in the pre-transition and the post-transition stage. In addition, impedance measurements were performed at room temperature on samples previously exposed to irradiation. This work clearly demonstrates that impedance spectroscopy can be used for in-situ studies of the corrosion of Zircaloy cladding materials in the pre-transition region at high temperatures. Oxide thickness, oxide conductivity, and effective donor density were successfully evaluated from the impedance data. Less information has been able to be gained from the impedance measurements in the post-transition region compared to the measurements in the pre-transition region. However, the thickness of the inner oxide layer, oxide conductivity, and oxide porosity were successfully evaluated from the impedance data. The measurements on irradiated samples of the same materials as investigated in autoclaves indicate that irradiation introduces defects in the oxide structure, resulting in a higher number of charge carriers and a more inhomogeneous oxide than produced under autoclave exposure.
Effect of Water Chemistry and Composition on Microstructural Evolution of Oxide on Zr Alloys
Authors: Zhou B. X. , Li Q. , Yao M. Y. , Liu W. Q. , Chu Y. L.
Published: September 2009

The microstructure of oxide films formed on Zircaloy-4 and Alloy No. 3, which has a composition similar to ZIRLO™, was investigated by high resolution transmission and scanning electron microscopy, and by scanning probe microscopy after corrosion tests performed at 360°C/18.6 MPa in deionized water or lithiated water with 0.01 M LiOH. The microstructural evolution of the oxide films was analyzed by comparing the microstructure at different depths in the oxide layer. The defects, consisting of vacancies and interstitials, such as points, lines, planes, and volumes, were produced during the oxide growth. Monoclinic, tetragonal, cubic, and amorphous phases were detected and their coherent relationships were identified. The characteristic of oxide with such microstructure had an internal cause, and the temperature and time were the external causes that induced the microstructural evolution during the corrosion process. The diffusion, annihilation, and condensation of vacancies and interstitials under the action of stress, temperature, and time caused stress relaxation and phase transformation. It was observed, in the middle of the oxide layer, that the vacancies absorbed by grain boundaries formed pores to weaken the bonding strength between grains. Pores formed under compressive stress lined up along the direction parallel to the compressive stress. Thus, cracks developed from the pores were parallel to the oxide/metal interface. Li+ and OH− incorporated in oxide films were adsorbed on the wall of pores or entered into vacancies to reduce the surface free energy of the zirconium oxide during exposure in lithiated water. As a result, the diffusion of vacancies and the formation of pores were enhanced, inducing the degradation of the corrosion resistance. The relationship between the corrosion resistance of zirconium alloys and the microstructural evolution of oxide films affected by water chemistry and composition is also discussed.
A New Model to Predict the Oxidation Kinetics of Zirconium Alloys in a Pressurized Water Reactor
Authors: Bouineau V. , Ambard A. , Bénier G. , Pêcheur D. , Godlewski J. , Fayette L. , Duverneix T.
Published: September 2009

The previous CEA corrosion code COCHISE provided satisfactory simulations of in-reactor corrosion of the fuel cladding when used in its validity range. In contrast, it could lead to hazardous predictions if applied out of this range due to the strongly linked parameters mainly based on the analysis of French pressurized water reactor (PWR) data. To predict the oxidation kinetics for new operating conditions or new materials, the CEA and EDF decided to develop a new model, named CORCY, which is based on a more phenomenological approach and uses separate parameters deduced from analytical experiments. The aim of this paper is to present the new model for Zircaloy-4 in PWR. The phenomenological approach is described. It is based on out- and in-pile data. Typically, since (1) the oxidation kinetics of zirconium alloys in autoclave are periodic, and (2) the oxide films formed in autoclave, in out-of-pile loop, and in-reactor all exhibit periodic lateral cracks with a period similar to the oxide thickness to transition, the oxidation kinetics in CORCY are characterized by a cyclic repetition of semi-parabolic law. Each model parameter is detailed. They are deduced separately from (a) oxidation tests performed in autoclave on fresh alloys to determine their kinetics; (b) oxidation tests performed in the out-of-pile corrosion loops Corail and Reggae to quantify the effects of thermo-hydraulic conditions; (c) data provided by Testing Material Reactors (OSIRIS and Halden reactor) during isothermal oxidation to determine the effects of irradiation; and (d) oxidation tests performed on pre-hydrided alloys to take into account the accelerated corrosion phase occurring, in reactor, for Zircaloy-4 at high burn-up. After describing both the phenomenological approach and the different model parameters, a comparison of measured and calculated corrosion data from French PWRs at a burn-up up to 65 GWd/tU is provided.
In PWR Comprehensive Study of High Burn-Up Corrosion and Growth Behavior of M5® and Recrystallized Low-Tin Zircaloy-4
Authors: Bossis Philippe , Verhaeghe Bénédicte , Doriot Sylvie , Gilbon Didier , Chabretou Valérie , Dalmais Agnès , Mardon Jean-Paul , Blat Martine , Miquet Alain
Published: September 2009

This paper is dealing with the corrosion and growth behavior of M5® and recrystallized low tin Zircaloy-4 irradiated as stress-free tubes in conditions representative of grids and guide-tubes of PWR fuel assemblies. The low-tin Zircaloy-4 tubes have reached equivalent burn-ups up to 93 GWd/tU (corresponding to a fluence of 21.0×1025 n·m−2, E>1MeV), and the M5® tubes have reached equivalent burn-ups up to 79 GWd/tU (corresponding to a fluence of 17.1×1025 n·m−2). Postirradiation growth was measured by comparing the distances between holes regularly distributed along the rod to the initial measurements. Postirradiation outer diameter oxide thicknesses were measured by eddy currents. Detailed characterizations of oxide layers have been realized through optical microscopy and scanning electron microscopy. Hydrogen uptake has been obtained through global hydrogen content measurements and metallographic examination of hydrides. Finally, the irradiation-induced microstructure of the metallic matrix has been observed by transmission electron microscopy. On these tubes, the free growth reached 1.9 % at 93 GWd/tU on Zircaloy-4 and 0.3 % at 79 GWd/tU on M5®. The external oxide thicknesses are far greater on Zircaloy-4 (∼60 μm at 93 GWd/tU) than on M5® (∼7.5 μm at 79 GWd/tU), and the oxidation rate is eight times higher on Zircaloy-4 than on M5®. Very high hydrogen content is achieved on Zircaloy-4, up to ∼1600 ppm (due to the low wall thickness and two-sided corrosion), whereas the maximum value on M5® is ∼100 ppm (despite the same geometry and corrosion conditions). On both alloys, the hydrogen pickup fraction is of the same order for these experimental empty rods as for previously analyzed fuel rod claddings, which may indicate the absence of a heat flux effect on the hydrogen uptake. Finally, potential correlation between growth, corrosion and hydrogen uptake will be discussed. Taking account of the results obtained on both experimental tubes and fuel rods, the effects of the presence or absence of heat flux through the wall thickness and of hydride rim at the metal/oxide interface are discussed, especially concerning the high burn-up corrosion acceleration on Zircaloy-4.
ZIRLO™ Cladding Improvement
Authors: Foster John Paul , Yueh H. Ken , Comstock Robert J.
Published: September 2009

Improvements to fuel design have been made in recent years to meet the challenges of increases in fuel duty in terms of linear power and operating temperature. Improved cladding material is one of these design improvements. Specifically, Westinghouse has developed an improved version of ZIRLO™ called Optimized ZIRLO and denoted as OPT ZIRLO. The Sn level in this improved material is reduced from the nominal standard previous level of about 1 % to a range of 0.6 % to 0.8 %. The reduced Sn level has been optimized to produce a higher corrosion resistance and provide adequate in-reactor creep resistance. Out-reactor diameter creep tests have shown that decreasing Sn increases out-reactor creep, suggesting that decreasing Sn may also increase in-reactor creep. An in-reactor testing program in the Vogtle Unit 2 pressurized water reactor (PWR) was performed to confirm the predicted in-reactor behavior. The test samples were suspended as segmented rods inside fuel assembly thimble tubes. In-reactor diameter creep data confirmed that decreasing Sn increases in-reactor creep. As a result of the correlation between in-reactor and out-reactor creep, an extensive out-reactor diameter creep program was performed in order to develop methods to fabricate OPT ZIRLO with the same in-reactor creep properties as the currently used stress-relief annealed standard ZIRLO (denoted as SRA STD ZIRLO). The level of in-reactor diameter creep of SRA STD ZIRLO was achieved for OPT ZIRLO by two methods. One method involved changing the final microstructure from SRA to partially recrystallized (PRXA). The other method kept the final microstructure as SRA and changed the tube reduction sequence to decrease the final tube area reduction. In order to develop these methods, a series of material variation tests was performed. Some of the material variations included different final heat treatments, different tube reduction sequences, and different pre-charged hydrogen levels. These tests were performed for both out-reactor and in-reactor. In addition, the out-reactor and in-reactor creep were observed to directly correlate for OPT ZIRLO material fabricated with different final anneal temperatures. Thus, out-reactor creep may be used to predict in-reactor creep properties for different final anneal temperatures. These results show that fabrication changes may be used to control in-reactor creep. In this study, fabrication changes were used to compensate for the reduction in in-reactor creep strength associated with lower tin content in OPT ZIRLO.
Chemistry of Waterside Oxide Layers on Pressure Tubes
Authors: Do T. , Saidy M. , Hocking W. H.
Published: September 2009

The pressure tubes that contain the fuel bundles and the primary coolant within the core of a CANDU heavy-water reactor are fabricated from a Zr-2.5Nb alloy with a complex microstructure. During reactor operation the pressure-tube interior surface is slowly oxidized by heavy water and a fraction of the deuterium that is released through this process enters the underlying alloy and can reduce its fracture toughness. Considerable variability in deuterium ingress has been observed among the pressure tubes within a single reactor as well as between different reactors. These differences are thought to be due not only to metallurgical variables, such as alloy microstructure and composition, but also to variations in the primary coolant chemistry, including pH and dissolved impurities. In the present study, a combination of surface analytical methods has been employed to characterize the microchemistry and oxidation history of the waterside oxide layers grown on two pressure tubes that were removed from different CANDU reactors. The presence of varying concentrations of iron, manganese and uranium, derived mainly from corrosion of feeder pipes and fuel failures, has been found throughout the oxide layers. An increase in the oxidation rate of one pressure tube later in life could be correlated with evidence of greater open porosity, provided by the depth distributions of impurities, extending deep within the oxide layer.
Deformation Anisotropy of Annealed Zircaloy-2 as a Function of Fast Neutron Fluence
Authors: Wei X. , Theaker J. R. , Griffiths M.
Published: September 2009

For unirradiated Zircaloys, plastic deformation occurs mostly by ⟨a⟩-type dislocation glide on prismatic planes. The critical resolved shear stress of the prismatic slip system is lower than that of the other deformation systems (⟨a⟩ slip on basal planes, and ⟨a⟩ or ⟨c+a⟩ slip on pyramidal planes, and twinning). This means that the yield strength (and ultimate tensile strength) for directions with a strong basal pole texture is higher than directions with a strong prism pole texture. Irradiation increases the yield stress on all slip planes due to the formation of dislocation loops that act as barriers to slip. Experimental evidence from Zircaloy-2 samples irradiated at 70°C suggests that the increase in critical resolved yield stress due to irradiation is lower for basal compared with prism planes.
Intergranular and Interphase Constraints in Zirconium Alloys
Authors: Holt R. A. , Daymond M. R. , Xu F. , Cai S.
Published: September 2009

We report the development of intergranular and interphase constraints in textured Zircaloy-2, Zr-2.5Nb, and Excel alloy during room temperature tension and compression loading in two or three directions relative to the parent texture. Neutron diffraction was used to track the lattice strain development in the α-phase (all alloys) and β-phase (Zr-2.5Nb and Excel) in three principal directions relative to the parent texture. Zircaloy-2 at room temperature is essentially single phase hcp αZr. The active deformation mechanisms appear to be, in order of increasing critical resolved shear stress, prism (a) slip, basal (a) slip, tensile twinning and pyramidal (c+a) slip. No compressive twinning was observed. Combined with intergranular constraints due to prior thermal treatment, these mechanisms result in substantial asymmetry in the yield stress and lattice strain development (compression versus tension). In Zr-2.5 Nb and Excel, the α-phase appears to deform by the same slip mechanisms as Zircaloy-2, and similar assymmetry of the yield stress and lattice strain development is observed. However, the existence of tensile twinning is not clearly evidenced. The β-phase also deforms by slip, but the critical resolved shear stress is much higher than that for the slip mechanisms in the α-phase, leading to the development of very large interphase constraints in the plastic deformation regime. This is attributed to a combination of solution strengthening of the β-phase (by Nb and, in Excel, Mo) and by grain size.
Bibliographical Abstracts of Methods for Analysis of Synthetic Detergents
Authors: Harris Jay C. , Bernstein Rubin
Published: September 2009

Since the issue of ASTM Special Technical Publication No. 150 in September, 1953, considerably greater interest in the analysis of synthetic detergents has become evident. The formation of 21 task groups of Joint AOCS-ASTM Subcommittee T-2 for the analysis of soaps and synthetic detergents has simply strengthened the need for this bibliography. As far as possible, the original references have been abstracted with the peculiar needs of the analyst in mind. Where original references were unavailable, abstract journals were used, and these are given in such cases as secondary references. No attempt has necessarily been made to trace the origin of specific techniques or methods, but where these were available, this has been done. Some references have been included which it was felt might have bearing upon the development of applicable methods. The first reference is dated 1888, much in advance of today's detergents, but is significant as the basis for techniques which may currently be used.
Significance of Tests for Petroleum Products
Authors: Boldt Kenneth , Hall B. R.
Published: September 2009

Description

This 20 year report includes valuable information for those concerned with protecting wire and wire products from the ravages of atmospheric exposure. Contains 28 tables, 36 graphs and 14 illustrations.
Bulgaria's Communist-Era Landscape
Authors: Kelleher Michael
Published: September 2009

This essay discusses the various architectural and design elements that helped define the communist-era landscape of Bulgaria. The conclusions presented here are based on observations made by the author while living in Bulgaria and research into the literature on communist architecture and design in the East Bloc. Bulgaria was the member of the East Bloc that most closely followed the architectural and design model established by the Soviet Union and exported to its satellite states following the Second World War. This didactic model was intended to present a certain image of communism and its achievements. Despite physical changes that came with the end of communism in Bulgaria, the country has retained a significant communist-era landscape. Bulgaria, therefore, presents an opportunity to examine many of the architectural and design elements typical of the East Bloc, both how the communists intended them to be interpreted and how these buildings and monuments made the transition to the postcommunist era.
Abandoned in Place: Interpreting the U.S. Material Culture of the Moon Race
Authors: Launius Roger D.
Published: September 2009

The U.S. space race of the 1960s was an enormous undertaking, costing $25.4 billion (about $125 billion in 2009 dollars) with only the building of the Panama Canal rivalling the Apollo program's size as the largest nonmilitary technological endeavor ever undertaken by the United States. In the process, the United States built a massive infrastructure to support missions to the Moon. In the aftermath of the successful completion of the program, much of this infrastructure was abandoned, some was altered for other uses, and much torn down. This paper surveys six major cultural landmarks of the Moon race, assessing their differing fates:1. The Apollo Launch Pads—LC 39A and B—Kennedy Space Center, Florida.2. The Vertical Assembly Building (VAB), Kennedy Space Center, Florida.3. Mission Control Center (MCC), Johnson Space Center, Houston, Texas.4. Six Apollo landing sites on the Moon.5. Lunar Landing Research Facility, Langley Research Center, Hampton, Virginia.6. Apollo Command Modules on display in various museums around the nation, and in London.
A comparative analysis of the zona pellucida birefringence of fresh and frozen–thawed human embryos
Authors: Gu Yi-Fan , Lu Chang-Fu , Lin Ge , Lu Guang-Xiu
Published: September 2009

The cryopreservation of human embryos is thought to induce alteration in the glycoprotein matrix and lead to zona change. However, this assumption has been full of controversies till now. The objective of this study was to evaluate the effect of cryopreservation on zona pellucida of human embryos. Fresh (n=106, from 40 patients) and frozen–thawed embryos (n=123, from 40 patients) were obtained from consenting patients who received conventional IVF and ICSI treatment. The birefringence of zona pellucida in human fresh and frozen–thawed embryos was imaged and quantitatively analyzed using polarized light microscopy before embryo transfer. There was no significant difference in retardance and thickness of the zona pellucida multilaminar structure between the two groups. Pregnancy and implantation rates of transferred fresh and frozen–thawed embryos were also compared. No significant difference was found in the rates of clinical pregnancy (47.5 vs 37.5%) and implantation (24.5 vs 23.2%) between the two groups. This study suggests that there is no significant change in the zona pellucida birefringence of human embryos before and after cryopreservation.
Impaired Health-Related Quality of Life in Children With Recurrent Pain
Authors: Petersen Solveig , Hägglöf Bruno Lars , Bergström Erik Ingemar
Published: September 2009

OBJECTIVE: The goal of the current study was to investigate self-reported, health-related quality of life (HRQoL) in a general population of young schoolchildren with recurrent pain (ie, headache, stomachache, or backache).

METHODS: The study was performed in Umeå, a university city in Sweden. All children in grades 3 and 6 were invited, and 97% participated (313 girls and 292 boys in grade 3 [mean age: 9.7 years]; 386 girls and 464 boys in grade 6 [mean age: 12.6 years]). Pain and HRQoL were measured with questionnaires.

RESULTS: Two thirds of the children reported recurrent pain (at least monthly). One third reported weekly pain, and 4 of 10 experienced pain from multiple locations. HRQoL impairment was twice as common among children with recurrent pain, compared with children without pain. All aspects of HRQoL (ie, physical, emotional, social, and school functioning and well-being) were impaired. The level of impairment was classified as considerable, especially for children who experienced pain from multiple body sites and children with weekly pain (Cohen's d = 0.6–0.8).

CONCLUSIONS: This study shows that young schoolchildren with recurrent pain have considerable impairment of their HRQoL.
Impact of Teen Depression on Academic, Social, and Physical Functioning
Authors: Jaycox Lisa H. , Stein Bradley D. , Paddock Susan , Miles Jeremy N. V. , Chandra Anita , Meredith Lisa S. , Tanielian Terri , Hickey Scot , Burnam M. Audrey
Published: September 2009

OBJECTIVE: This study aimed to determine the impact of teen depression on peer, family, school, and physical functioning and the burden on parents.

METHODS: Patients participated in a longitudinal study of teens with and without probable depression, drawn from 11 primary care offices in Los Angeles, California, and Washington, DC. A total of 4856 teens completed full screening assessments; 4713 were eligible for the study, and 187 (4.0%) met the criteria for probable depression and were invited to participate, as were teens who were not depressed. A total of 184 baseline assessments for teens with probable depression and 184 for nondepressed teens were completed, as were 339 (90%) parent interviews. Follow-up interviews were conducted with 328 teens (89%) and 302 parents (82%). Measures included teen reports of peer and parent support, 2 measures of school functioning, grades, physical health, and days of impairment. Parent reports included peer, school, and family functioning and subjective and objective burdens on parents.

RESULTS: Teens with depression and their parents reported more impairment in all areas, compared with teens without depression at baseline, and reported more coexisting emotional and behavioral problems. Both depression and coexisting problems were related to impairment. There was a lasting impact of depressive symptoms on most measures of peer, family, and school functioning 6 months later, but controlling for coexisting baseline emotional and behavioral problems attenuated this relationship for some measures.

CONCLUSION: Improvements in teen depression might have benefits that extend beyond clinical symptoms, improving peer, family, and school functioning over time.
Impact of Family Presence During Pediatric Intensive Care Unit Rounds on the Family and Medical Team
Authors: Aronson Paul L. , Yau Jennifer , Helfaer Mark A. , Morrison Wynne
Published: September 2009

OBJECTIVES: Our objectives were to determine the impact of family presence during PICU rounds on family satisfaction, resident teaching, and length of rounds and to assess factors associated with family satisfaction.

METHODS: This was an observational study of a convenience sample of morning work rounds in a PICU, followed by surveys of family members of patients in the unit and residents who had been present for rounds.

RESULTS: A total of 411 patient encounters were observed, 98 family questionnaires were fully completed, and 33 resident questionnaires were completed. Ninety-eight percent of family members liked to be present for rounds. On the first day of admission, family members were less likely to understand the plan (P = .03), to feel comfortable asking questions (P = .007), or to want bad news during rounds (P = .009). They were more likely to have privacy concerns (P = .02) and to want 1 individual to convey the plan after rounds (P = .01). Higher education level was associated with decreased privacy concerns (P = .002) but did not affect understanding of the plan. Fifty-two percent of residents perceived that teaching was decreased with families present. Time spent with individual patients was not increased by family member presence (P = .12).

CONCLUSIONS: Family satisfaction is high, but families of patients on the first day of admission may need special attention. The medical team should conduct rounds in a manner that addresses the privacy concerns of families. Residents often think that teaching is decreased when families are present.
Policy Statement—Recommendations for the Prevention and Treatment of Influenza in Children, 2009–2010
Authors:   Committee on Infectious Diseases
Published: September 2009

The purpose of this statement is to update current recommendations for routine use of trivalent seasonal influenza vaccine and antiviral medications for the prevention and treatment of influenza in children.
Epistasia para a produção de grãos em soja
Authors: Barona Marco Antonio Acevedo , Colombari Filho José Manoel , Geraldi Isaias Olivio
Published: September 2009

Em soja [Glycine max (L.) Merrill], a produção de grãos é o caráter de maior importância econômica, com herança quantitativa e altamente influenciado pelo ambiente. As estratégias de seleção utilizadas para o desenvolvimento de cultivares em soja poderiam ser otimizadas por meio do estudo da importância relativa dos componentes de variância, particularmente a proporção de variação devida às interações não alélicas (epistasia). Com o objetivo de estudar a variação epistática para a produção de grãos em soja utilizou-se o delineamento "Triple Test Cross Modificado" (TTC) de Jinks et al. Uma amostra de 32 linhas puras (Pi) derivadas de um cruzamento biparental foi cruzada com duas linhagens divergentes (L1 e L2) contrastantes para PG, derivadas da mesma população. O experimento de avaliação foi desenvolvido no ano agrícola de 2006/2007 em um delineamento em látice triplo triplicado (9 repetições), contendo 100 tratamentos: 32 cruzamentos Pi x L1 (L1i), 32 cruzamentos Pi x L2 (L2i), 34 linhas puras (32 Pi mais dois testadores) e duas testemunhas comerciais. A variação entre os contrastes de médias (L1i + L2i - Pi) foi altamente significativa na análise de variância (P<0,01), indicando a ocorrência de epistasia. Os resultados gerais indicam, portanto, que a epistasia pode ser um componente importante para a expressão da produção de grãos de soja e, consequentemente, esta deve ser incluída nos modelos para a decomposição dos componentes da variância genética.
Produtividade de rúcula e tomate em função da adubação N e P orgânica e mineral
Authors: Cavallaro Júnior Mario Luiz , Trani Paulo Espíndola , Passos Francisco Antônio , Kuhn Neto Jorge , Tivelli Sebastião Wilson
Published: September 2009

Visando comparar a eficácia de diferentes fertilizantes minerais e orgânicos, fontes de N e P, foram instalados experimentos com rúcula, sob cultivo protegido, no Instituto Agronômico, Campinas (SP), de outubro a novembro de 2004, e com tomate, no Sítio São João, Elias Fausto (SP), de setembro de 2004 a fevereiro de 2005. Para rúcula estudaram-se quatro doses de N (0; 50; 100; 150 kg ha-1 de N) e quatro doses de P (0; 100; 200; 300 kg ha-1 de P2O5) em pré-semeadura e em cobertura, utilizando-se os fertilizantes MAP; DAP; farinha de casco e chifres (FCC) e farinha de ossos (FO). Para tomate, foram estabelecidos dois experimentos: no primeiro, estudaram-se quatro doses de N em cobertura (0; 133; 266 e 399 kg ha-1 de N), utilizando-se nitrato de amônio (NA) e FCC, com dose fixa de P no pré-transplante, com o superfosfato triplo (ST). No segundo estudaram-se quatro doses de P no pré-transplante (0; 250; 500; 750 kg ha-1 de P2O5), utilizando-se ST e FO, com dose fixa de N em cobertura, como NA. Com a adubação com 75 kg ha-1 de N e 300 kg ha-1de P2O5 do MAP + DAP na pré-semeadura e com 75 kg ha-1 de N da FCC em cobertura foram proporcionadas produções maiores de rúcula. A adubação orgânica com FCC foi mais eficaz quando aplicada por ocasião da pré-semeadura. Concluiu-se que FCC foi a fonte mais eficaz de N em relação ao NA para produção e massa média dos frutos de tomate e ST, como fonte de P em relação à FO, para produção de tomate.
Controle de tiririca com sulfentrazone e diclosulam e viabilidade de tubérculos em diferentes profundidades de solo
Authors: Martins Dagoberto , Tomazela Mario Sergio , David Domingos Vanessa , Martins Cibele Chalita
Published: September 2009

O objetivo deste estudo foi avaliar a eficiência dos herbicidas sulfentrazone e diclosulam no controle de tiririca Cyperus rotundus L. na cultura da cana-de-açúcar e determinar a viabilidade dos tubérculos. O delineamento experimental utilizado foi em blocos inteiramente casualizados, com quatro repetições onde foram dispostos os tratamentos referentes às cinco doses de diclosulam (75, 100, 150, 200 e 250 g ha-1), duas doses de sulfentrazone (800 e 1.000 g ha-1), além de duas testemunhas, uma capinada e outra sem capina. Aos 110 dias após a aplicação dos herbicidas, retiraram-se três subamostras de solo nas profundidades de 0 a 10 e 10 a 20 cm, tanto do sulco de plantio como do camalhão. Os tubérculos de tiririca das amostras de solo foram colocados para germinar em casa-de-vegetação a fim de avaliar sua viabilidade. Após 45 dias da aplicação, os herbicidas propiciaram controles considerados de regular a excelente (75,8 a 96,0%). No sulco de plantio, todas as doses de ambos os herbicidas reduziram o número de tubérculos dormentes nas duas profundidades estudadas. No camalhão, as doses de diclosulam de 100 e 150 g ha-1 aumentaram a mortalidade de tubérculos em 38% e 63%, respectivamente. As doses intermediárias de diclosulam (150 g ha-1) propiciaram alta mortalidade de tubérculos e doses elevadas (250 g ha-1) induziram à dormência no sulco de plantio.