bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Niobium and Vanadium on the Microstructure and Mechanical Properties of Submerged-Arc Welds Produced Under a Basic Flux in Carbon-Manganese Steels
Authors: Abson DJ , Hart PHM
Published: March 2009

Two-pass tandem submerged-arc welds have been deposited in 25-mm-thick, silicon-killed, aluminum-treated steel plate containing different levels of niobium and vanadium, all of the same base composition, 0.14C-0.3Si-1.4Mn-0.04Al. Two vanadium-containing steels with a high nitrogen content were also included. The range of plate compositions included those which would be used for controlled rolled and quenched and tempered steels. The effects on weld metal Charpy toughness of the microalloying additions were compared with those from previous work, and crack-tip opening displacement (CTOD) data were generated for submerged-arc welds in such steels. For this, the first phase of a larger program, a basic agglomerated flux was used, and the arc energy (for the second pass) was 4.9 kJ/mm. Welding was carried out using S1 (0.5Mn), S2 (1Mn), and S3Mo (1.5Mn-0.5Mo) wire so that the influence of the microalloying additions on different initial microstructures could be studied. Three weld deposit levels of niobium (∼0.2, ∼0.03, and ∼0.07 percent) and two of vanadium (∼0.06 and ∼0.11 percent) were studied.

For the majority of the welds, the Charpy and CTOD properties of the as-desposited weld metal were good (the 27-J temperature was generally < −50 °C and the 0.1-mm CTOD temperature generally < −60 °C). The microalloy additions had comparatively little effect on the microstructure except when low levels of niobium (<0.02 percent) were added to lean alloy (1.2Mn) deposits, when a marked increase in acicular ferrite content occurred. An increase in 27-J temperature and in 0.1-mm CTOD temperature was commonly observed but was generally <15 °C for the highest levels of microalloy additions. Hardness increases in reheated weld metal generally became greater with increases in microalloy content, and this was reflected in a rise in the 0.1-mm CTOD temperature, particularly for the S3Mo deposits. In contrast, the Charpy tests revealed little influence of microalloying in the S3Mo deposits, while in the S2 deposits the effect depended strongly on the level of niobium.
Use of Material Tests and Pavement Design Procedures to Evaluate New Paving Binders
Authors: Kennedy TW , White TD , Epps JA
Published: March 2009

Experience and a review of practice indicate new paving materials and technology are being evaluated with empirical tests. The evaluations are comparative, usually including a familiar asphalt in binder tests or a favorite aggregate in paving mixture tests. Generally, at least one type of water sensitivity test would be applied in the evaluation. Rational tests such as creep modulus and fatigue tests are being used to some extent but meet resistance because of lack of equipment and experience, both with the tests and meaning of the results.

An attempt is made to supply background on both the empirical and rational tests that are used in evaluating modified asphalts or replacement binders for asphalt. The background discussion is considered timely for long-used empirical tests as well as newer rational tests because of the insight such discussion can offer in considering the potential changes facing the pavement industry today.

Drawing on the background discussion, test results on sulfur-extended asphalt, recycled asphalt, and polymerized asphalt are specifically included in the paper because they are materials currently undergoing evaluation in the United States and around the world.
Effect of Load Frequency and Lay-Up on Fatigue Life of Composites
Authors: Saff CR
Published: March 2009

Recent research programs have indicated that the frequency of cyclic loading has a significant effect on the fatigue life of certain composite materials and lay-ups. In some cases, reduction in loading frequency has resulted in a proportional reduction in fatigue life. In these cases, data from high-frequency fatigue tests do not provide accurate assessment of life for service loadings which occur at much lower rates. In many of these test programs, materials, lay-ups, and loading frequencies were selected to examine the effect of load frequency on matrix degradation and fatigue life. These materials and loading frequency selections are not representative of those used in aircraft structures.

The current program was performed to examine the effect of cyclic loading frequency on the fatigue life of lay-ups which represent those used in aircraft structure. Fatigue tests on three AS/3501-6 graphite/epoxy laminates were performed at frequencies ranging from 0.1 to 10 Hz. Tests of a (±45)2s lay-up gave results similar to those of Sun and Chan for the same lay-up in T300-5208 graphite/epoxy. At low frequencies, the AS/3501-6 material appeared to follow the data from T300-5208. But at 10 Hz the life for AS/3501-6 was one tenth that of the T300-5208 material.

Lay-ups having 0° plies were found to have a lesser, but still significant, effect of frequency on fatigue life. Life for these specimens increased by factors of 3 to 4 when load frequencies were increased by a factor of 100. Preliminary analyses indicate that the sensitivity of fatigue life to load frequency appears related to the matrix stress state. Fatigue life sensitivity was correlated with the ratio of matrix shear stress to applied axial stress.
Compression Fatigue Damage in Thick, Notched Graphite/Epoxy Laminates
Authors: Black NF , Stinchcomb WW
Published: March 2009

This study has investigated the damage development mechanisms in notched graphite/epoxy composite laminates during constant-amplitude compressive fatigue loading. Laminates of two different stacking sequences were tested. The relationship between fatigue damage and the resulting life, stiffness, and strength of the laminates have been observed. X-ray radiography and ultrasonic C-scanning were used to characterize and monitor the damage that occurred during the fatigue loadings. Sectioning of the damaged laminates was performed to verify the extent of the observed damage in the X-ray radiographs and ultrasonic C-scans.

Damage in both laminate types consisted of matrix cracking and delaminations. The growth of the damage was observed to have a three-dimensional nature.
Sampling, Analytical, and Quality Assurance Protocols for the National Atmospheric Deposition Program
Authors: Peden ME
Published: March 2009

The increasing concerns regarding the quality of precipitation falling on the United States resulted in the formation of the National Atmospheric Deposition Program (NADP) in 1978. The first phase of the program, which was the development of a nationwide monitoring network, was organized in July 1978 by the North Central Region of the State Agricultural Experiment Stations. Currently, 90 sites across the country are participating in the collection of wet and dry deposition samples that are sent to a Central Analytical Laboratory (CAL) located at the Illinois State Water Survey. Site operators are required to determine pH and specific conductance before shipping samples to the CAL. Upon arrival, samples are analyzed for eleven parameters that include pH and specific conductance. To ensure reliable analytical results both at the field sites and at the CAL, a quality assurance program has evolved that includes intersite comparisons for pH and specific conductance, computer verification of all analytical results, plus the extensive use of “blind” samples. Details of the internal controls used at the CAL are documented with supporting data from the first three years of network operations.
Use of Coatings to Improve Fire Resistance of Wood
Authors: White RH
Published: March 2009

Currently used fire retardant coatings for wood products reduce flame spread; they are not designed specifically to provide fire resistance. Fire resistive coatings designed for steel and foam plastics generally are not recommended for wood. Small nonload-bearing fire resistance tests were conducted in this study to determine the fire resistance of eight commercially available fire retardant and fire resistive coatings when applied to a wood product.

Coated plywoods over a foam plastic substrate were tested in a small-scale vertical exposure furnace in accordance with ASTM Fire Tests of Building Construction and Materials (E 119-82). The results were the times for the temperature rise to reach an average value of 139°C (250°F) or a maximum value of 181°C (325°F) at the plywood/foam-plastic interface. Uncoated plywoods were tested as controls.

Fire retardant coatings improved the times for plywood specimens by up to 900 s, and fire resistive coatings showed a 240- to 2640-s improvement over uncoated plywood. Coatings significantly improved the fire resistance of a wood product. The fire resistance data reported in this paper should aid in future considerations of fire resistive coatings in wood construction.
Fatigue Fracture Surface Micromorphology in Poly(vinyl chloride)
Authors: Rimnac CM , Hertzberg RW , Manson JA
Published: March 2009

The fatigue fracture surface micromorphology of poly(vinyl chloride) (PVC) was studied as a function of molecular weight (M), plasticizer content, and residual orientation, with particular attention given to how these variables affect the formation of discontinuous growth bands (DGBs). Discontinuous growth bands, which form on a number of polymeric solids under cyclic loading, represent successive increments of crack extension through a craze zone. As expected, DGB width showed little change in size over the molecular weight range or specimen orientations examined and increased in size with increasing plasticizer content. On the other hand, the cyclic stability of these bands increased markedly with an increase in molecular weight, but to a lesser extent with additions of a plasticizer. The internal structure of the bands became more ragged with increasing M, whereas the addition of a plasticizer reestablished the crisp and well-defined micromorphology associated with DGBs in low-M polymers.
Quantitative Fractography of a Fatigued Ti-28V Alloy
Authors: Underwood EE , Chakrabortty SB
Published: March 2009

A quantitative fractographic analysis was undertaken in order to relate important microstructural and fractographic features to fatigue fracture in a Ti-28V alloy. Special emphasis is placed on facet characteristics and subsurface cracking in the single-facet and multifacet regions.

The stereological treatment of this problem develops methodologies and relationships based primarily on vertical sections cut through the fracture surface and parallel to the crack propagation direction. The evaluation of fracture profiles (in terms of true length, roughness, and degree of orientation) permits calculation of fracture surface characteristics (such as true surface area, roughness, and type of surface).

True mean facet areas, Āfacets, are calculated from combined measurements on scanning electron microscope photographs and two parallel, vertical sections along the edge and center of the fracture surface. The values of Āfacets for the single-facet and multifacet regions are 22.2 ± 4.9 and 12.7 ± 4.0 nm2, respectively, with indicated 95 percent confidence intervals. True mean subsurface crack lengths, ¯Lcracks, in the edge section are 0.05 ± 0.07 and 0.16 ± 0.07 mm for the single-facet and multifacet regions, respectively, whereas in the center section the corresponding values are 0.13 ± 0.08 and 0.34 ± 0.13 mm. Based on an upper-lower bound approach, the fracture surface is found to conform most closely to a partially oriented surface with strong planar elements. The results obtained here are consistent with the fatigue crack growth model of Chakrabortty.
Quantitative Measurements of the Growth Kinetics of Small Fatigue Cracks in 10Ni Steel
Authors: Gangloff RP
Published: March 2009

An experimental method, developed to monitor the formation and subcritical propagation of small surface cracks, was evaluated and confirmed by comparisons with conventional “large” crack data. Analytical procedure were developed to produce quantitative crack growth rate—stress-intensity data from measured electrical potential values. Accurate and reproducible results were obtained for surface-defected specimens of 10Ni steel, machined from the heat of material investigated in an ASTM interlaboratory exchange program. Specifically, crack growth rates between 10−6 and 10−3 mm/cycle were correlated uniquely with the stress-intensity range, independent of crack depth (0.10 to 0.80 mm) and applied stress (30 to 90 percent of σys). Data obtained for small surface cracks were in excellent agreement with the growth rate—stress-intensity relationship developed based on conventional tests with compact tension and center crack panel specimens. Accelerated cracking, associated with “short” crack effects, was not observed. The electrical potential monitoring technique for small surface cracks was qualified for investigations of “short” crack effects, and for screening studies requiring timely data acquisition.
Development of a Canadian Data Base on Waste Leachability
Authors: Côté PL , Constable TW
Published: March 2009

A number of wastes from various locations across Canada were subjected to a set of leaching tests. Each set consisted of six batch extractions using three leaching media (distilled water, an acidic solution buffered at pH 4.5, and a synthetic municipal landfill leachate) at two liquid-to-solid ratios (4:1 and 20:1). The preliminary data from 19 wastes were examined to gain a better understanding of the effects that different leaching media and liquid-to-solid ratios have on contaminant release.

When distilled water was used as the leaching medium, the final pH of the leachate was controlled by the alkalinity of the waste. Changing the liquid-to-solid ratio had little effect on leaching pH. The difference in the concentrations observed at the two liquid-to-solid ratios was the result of dilution in many cases.

When an acidic solution or synthetic leachate was used as the leaching medium, final leachate pH appeared to be a function of the interaction between the waste pH and the amount of acid available in the leaching medium to react with the waste. Increasing the liquid-to-solid ratio increased the amount of acid contacting the waste and shifted the leachate pH towards the pH of the leaching medium.

Use of a synthetic leachate appeared to complex some contaminants and increase their release above that to be expected from pH-solubility considerations alone.

Linear relationships were observed between the leachate pH and the logarithm of the release for some wastes and contaminants. Knowledge of this relationship would make it possible to interpolate or extrapolate results of leaching tests performed on the same waste under different test conditions.

Contaminant release from the same waste can vary over several orders of magnitude within a short pH range. Therefore, final leachate pH should be included when reporting the results of a batch leaching test.
In VitroEvaluation of the Channel CatfishIctalurus punctatus(Rafinesque) as a Test Species in Chemical Carcinogenesis Studies
Authors: Hinton DE , Klaunig JE , Jack RM , Lipsky MM , Trump BF
Published: March 2009

The ability of isolated subcellular fractions and cells from the liver of channel catfish Ictalurus punctatus (Rafinesque) to perform key steps in carcinogenesis was studied using the polycyclic aromatic hydrocarbon (PAH) benzo[a]pyrene (BP). Highpressure liquid chromatographic (HPLC) analysis of BP metabolism by catfish liver microsomal fraction revealed the formation of 9,10-diol BP; 4,5-diol BP; 7,8-diol BP; 9-OH BP; 3-OH BP; and quinones. When the microsomal fraction of catfish liver from fish pretreated with 3-methylcholanthrene was used, increased formation of 9,10-diol BP and 7,8-diol BP was seen. Postmitochondrial supernatant (S-9) of catfish liver incubated with required cofactors activated 2-acetylaminofluorene and BP into mutation-causing metabolites in a bacterial mutagen assay. Trypsin digestion of catfish liver was used to isolate 2.8 × 106 cells/g liver with 98 percent viability. Incubation of these cells after 1 day of culture with tritiated BP followed by autoradiographic localization showed preferential accumulation of BP over liver cell nuclei. Subsequent liquid scintillation analysis of cell fractions obtained by cesium chloride centrifugation revealed radioactivity in the deoxyribonucleic acid (DNA) fraction. Results of studies with microsomal fractions demonstrate the capacity of the liver mixed-function oxidase system (MFOS) of this species to metabolize carcinogens into mutagenic forms. Data with isolated cells indicate that activation reactions could result in the initiation of carcinogenesis within the intact liver and suggest the suitability of this species for carcinogen bioassay.
Approach to the Analysis of Toxicant Interactions in the Aquatic Environment
Authors: Durkin PR
Published: March 2009

Most methods currently used to evaluate the joint action (the effects of toxicants applied in combination) of two toxicants rely on toxicity estimates of the individual components and one mixture. For both theoretical and practical reasons, such approaches are unsatisfactory oversimplifications that are insensitive when applied to experimental data. Although isoboles can be used to illustrate interactive patterns for several mixtures, direct statistical analyses of isoboles are awkward because the variances are not restricted to a single axis. An alternative approach is proposed based on a comparison of the assumption of simple similar action with two models of interactive joint action.
Defects and Carrier Lifetime in Silicon
Authors: Rohatgi A , Rai-Choudhury P
Published: March 2009

The effects of substrate cleaning, high-temperature processing, epitaxial growth, and impurities on carrier lifetime and defects in silicon are investigated. Because of the possible accumulation of particulate contamination from deionized water, there appears to be an optimum rinse time for the final substrate-cleaning step. POCl3, HCl, and back-surface damage gettering techniques improve carrier lifetime and reduce defect density, provided the samples are slow cooled. Generation lifetimes of several milliseconds are obtained from the combined use of back-surface damage and HCl or POCl3 gettering. Carrier lifetimes in epitaxial silicon can be improved by treating the substrates with a chelating solution that removes heavy metals from the surface. Epitaxial layers grown on heavily phosphorus-doped substrates have higher life-times than those grown on lightly phosphorus-doped or heavily antimony-doped substrates. Metallic impurities in the concentration range of 1011 to 1016 cm−3 can be detrimental to the carrier lifetime, and their influence can vary with the mode of incorporation and thermal history of the wafer. High-temperature gettering can mitigate the adverse effect of a fast-diffusing impurity in silicon like chromium, but it has negligible influence on a very slow diffuser like molybdenum.
Intensity Dependent Absorption of Alkali-Halides at 10.6 μm
Authors: Wu S-T , Bass M
Published: March 2009

Repetitively pulsed laser calorimetry has been developed and applied to measure the intensity dependent absorption of NaCl, KCl and KBr at 10.6 μm. The absorption increases as much as 70% at high laser intensity. Furthermore, multipulse damage data was obtained for KBr which indicates that the absorption increases very rapidly at intensities just below the single pulse damage threshold. The functional form of this phenomenon is still not well characterized. A simple model is suggested and the course of necessary additional investigations is discussed in this paper.
Stress-Induced Birefringence, Critical Window Orientation, and Thermal Lensing Experiments
Authors: Klein CA
Published: March 2009

A proper assessment of thermal lensing phenomena in high-average-power laser windows involves an evaluation of two optical distortion coefficients: (a) the coefficient X+, which combines the effects of temperature-induced change in refractive index, surface bulging through constrained expansion, and photoelasticity averaged over the principal stress directions, and (b) the coefficient X−, which exists only if there is stress birefringence. This evaluation can be performed for 111 — oriented and for randomly-oriented aggregates of cubic single crystals. It is emphasized that the calculations require correct inputs in terms of elastic and photo-elastic coefficients. Among presently contemplated key laser-window material candidates, only CaF2 can exhibit significant stress-birefringence effects; this is not so in the 111 orientation, which reflects a critical situation in the sense of Joiner, Marburger, and Steier. Windows made of KCl exhibit isotropic distortion patterns because the magnitude of the thermo-optic coefficient is such that the “small-birefringence condition,” X−/X+ << 1, is satisfied. The results of interferometric testing substantiate these considerations.
The Role of Absorbing Defects in the Laser Damage of Transparent Materials
Authors: Danileiko YK , Manenkov AA , Nechitailo VS
Published: March 2009

In early studies of laser induced damage, it was found that absorbing defects, like platinum metallic inclusions in glasses [1] considerably reduce the damage threshold. This fact has motivated numerous experimental and theoretical Investigations of the role of absorbing defects in laser damage of transparent optical materials of different kinds (crystals, glasses, polymer materials). In a short paper it 1s impossible, of course, to present a review of all the experimental results and theoretical ideas concerning the influence of absorbing defects on laser damage processes. Therefore, in this paper, we restrict ourselves to only a brief review of research carried out in our laboratory at the Lebedev Physics Institute. For more complete and detailed information on this research, the reader should refer to the collection of [2] papers in which a summary of research carried out by other groups is presented as well. Extensive Information on the problem under discussion can also be found in the proceedings of the Laser Damage Symposium [3–4].
Stress-Intensity Factor Equations for Cracks in Three-Dimensional Finite Bodies
Authors: Newman JC , Raju IS
Published: March 2009

This paper presents empirical stress-intensity factor equations for embedded elliptical cracks, semielliptical surface cracks, quarterelliptical corner cracks, semielliptical surface cracks at a hole, and quarterelliptical corner cracks at a hole in finite plates subjected to remote tensile loading. These equations give stress-intensity factors as a function of parametric angle, crack depth, crack length, plate thickness, and, where applicable, hole radius. The stress-intensity factors used to develop the equations were obtained from current and previous three-dimensional finite-element analyses of these crack configurations. A wide range of configuration parameters was included in the equations. The ratio of crack depth to plate thickness ranged from 0 to 1, the ratio of crack depth to crack length ranged from 0.2 to 2, and the ratio of hole radius to plate thickness ranged from 0.5 to 2. The effects of plate width on stress-intensity variations along the crack front also were included, but generally were based on engineering estimates. For all combinations of parameters investigated, the empirical equations were generally within 5 percent of the finite-element results, except within a thin “boundary layer” where the crack front intersects a free surface. However, the proposed equations are expected to give a good estimate in this region because of a study made on the boundary-layer effect. These equations should be useful for correlating and predicting fatigue crack growth rates as well as in computing fracture toughness and fracture loads for these types of crack configurations.
A Critical Analysis of Grain-Size and Yield-Strength Dependence of Near-Threshold Fatigue Crack Growth in Steels
Authors: Yoder GR , Cooley LA , Crooker TW
Published: March 2009

Near-threshold fatigue crack growth behavior has been analyzed for a broad selection of steels surveyed from the literature. It is clear first of all that apparent values of the threshold stress-intensity factor (ΔKth) can vary widely, roughly an order of magnitude. Though in many instances actual ΔKth values are difficult to define rigorously, a pronounced transition point or “knee” is apparent in the near-threshold region of the conventional logarithmic plot of fatigue crack growth rate (da/dN) as a function of stress-intensity range (ΔK). Though the values of ΔK associated with these transition points (ΔKT) for an individual steel may tend to exhibit a functional dependence on yield strength (σys) or grain size (¯ℓ)—as is the case, for example, with a low-carbon ferritic steel—it is unmistakably clear that for the gamut of steels examined (15 cases), the transition points do not order on the basis of either σys or ¯ℓ alone. Rather, values of ΔKT for the gamut of steels order on the basis of a synergetic interaction of σys and ¯ℓ, according to the equation, ΔKT=5.5σysℓ¯. This relationship was derived in the cyclic plastic zone model of fatigue crack growth established in our prior work with titanium alloys. In further agreement with this model, ΔKT has been identified for these steels as the point at which the cyclic plastic zone attains the mean grain size. The significance and implications of these findings appear far-reaching, as the steels surveyed include those of both high and low strength, a wide range of effective grain sizes (mean free path in the case of high-strength steel), and a host of microstructural types (ferritic, martensitic, pearlitic, bainitic, and austenitic).
Improving the Bulk Laser-Damage Resistance of KDP by Baking and Pulsed Laser Irradiation
Authors: Swain JE , Stokowski SE , Milam D , Rainer F
Published: March 2009

Isolated bulk damage centers are produced when KDP crystals are irradiated by 1-ns 1064-nm pulses. We have tested about 100 samples and find the median threshold to be 7 J/cm2 when the samples are irradiated only once at each test volume (1-on-1 tests). The median threshold increased to 11 J/cm2 when the test volumes were first subjected to subthreshold laser irradiation (n-on-1 tests). We baked several crystals at temperatures from 110 to 165°C and remeasured their thresholds. Baking increased thresholds in some crystals, but did not change thresholds of others. The median threshold of baked crystals ranged from 8 – 10 J/cm2 depending on the baking temperature. In crystals that had been baked, subthreshold irradiation produced a large change in the bulk damage threshold, and reduced the volume density of damage centers relative to the density observed in unbaked crystals. The data is summarized in the table.
Crack-Tip Stress Fields and Crack Growth Under Creep-Fatigue Conditions
Authors: Riedel H
Published: March 2009

Fatigue crack growth at elevated temperatures is a complicated problem since widespread creep deformation, in addition to elastic deformation, can accompany crack extension, and since the micromechanisms of crack growth comprise grain boundary cavitation, the striation mechanism, and corrosive effects. In the present paper, the time-dependent crack-tip stress fields in an elastic-nonlinear viscous body are analyzed for variable load. From the results, it is concluded that for slow cycling the C*-integral is the load parameter that determines the crack-tip fields and therefore the crack growth rate. If rapid load variations occur within otherwise slow cycles, the stress intensity factor, ΔKI, also affects the crack-tip fields; ΔKI determines the severity of the stress peaks that follow rapid load changes. For rapid cycling, the time-dependent stressing and straining near the crack tip is governed by ΔKI. If rapid cycling is unbalanced, a time-dependent component is superimposed on the rapidly varying ΔKI-controlled field. This time-independent component can be described by the C*-integral only for R-ratios near unity (that is, for high mean stress and small amplitude). The general case of unbalanced rapid cycling remains unresolved. Characteristic frequencies ω1 are developed to distinguish slow and rapid cycling, and a characteristic time t1 is given to decide whether a given load increase within a cycle is rapid or slow.

The stress fields are combined with simple models for the striation and cavitation mechanisms of crack growth. The resulting crack growth rates, da/dN, are compared with a small number of experimental results from the literature.
Crack-Tip Stress and Deformation Fields in a Solid with a Vertex on Its Yield Surface
Authors: Needleman A , Tvergaard V
Published: March 2009

For deeply cracked specimens a finite strain numerical analysis is employed to investigate the development of the near-tip stress and strain fields during cracktip blunting. The material is characterized by an elastic-plastic constitutive law with a vertex on subsequent yield surfaces at the point of loading, as suggested by physical models of polycrystalline aggregates. In contrast to classical smooth yield surface theory, this corner theory of plasticity permits shear band formation at achievable strain levels in work-hardening solids. Both for an edge-cracked bend specimen and for a center-cracked panel the corner theory description results in localization into shear bands in a small material region near the crack tip, so that very high strain peaks develop at an early stage of blunting. An edge-cracked bend specimen computation based on the classical Prandtl-Reuss plasticity theory, carried out for comparison purposes, shows a smooth variation of the strain field around the blunting crack tip. For the two edge-cracked bend specimens the stress and strain fields a few openings away from the tip are, however, in close agreement.
Recent Progress with Ethyleneoxy Phosphazenes as Lithium Battery Electrolytes
Authors: Fei Shih-To , Allcock Harry R.
Published: March 2009

We report here a series of high-conductivity liquid- and gel-electrolytes based on a mixture of ethyleneoxy phosphazenes and propylene carbonate, which have potential applications in lithium battery assembly. Phosphazene compounds are known to be good materials for solid polymer lithium electrolytes and, following that idea, we have developed low-volatility liquid phosphazene electrolytes that maintain 10−4 S/cm conductivity. A high conductivity of 10−3 S/cm can be achieved when polymeric phosphazenes are used as solidifying agents for conventional battery electrolytes. We also report here the fire retardant properties of the materials, which may lead to future use of these materials as fire retardant additives.
New Pt-based Superalloy System Designed from First Principles
Authors: Razumovskiy Vsevolod I. , Isaev Eyvaz I. , Ruban Andrei V. , Korzhavyi Pavel A.
Published: March 2009

Pt-Sc alloys with the γ-γ′ microstructure are proposed as a basis for a new generation of Pt-based superalloys for ultrahigh-temperature applications. This alloy system was identified on the basis of first-principles calculations. Here we discuss the prospects of the Pt-Sc alloy system on the basis of calculated elastic properties, phonon spectra, and defect formation energies.
Effect of Atrazine and Mesotrione on Centipedegrass Growth, Photochemical Efficiency, and Establishment
Authors: McElroy J. Scott , Walker Robert H.
Published: March 2009

Centipedegrass is tolerant of both atrazine and mesotrione when applied separately to established turf. However, no information is available regarding the use of mesotrione or the synergistic mixture of atrazine plus mesotrione applied to centipedegrass during seeded establishment. Research was conducted to evaluate centipedegrass tolerance to various rates and combinations of atrazine plus mesotrione when applied 14 d after emergence (DAE). Experiment 1 evaluated centipedegrass tolerance to atrazine and mesotrione in a broad rate-range screen in a greenhouse environment. Variations were observed between greenhouse trial runs with respect to injury and biomass with less injury and decrease in biomass observed in run 2. Overall, atrazine alone and atrazine plus mesotrione were more injurious for a greater time period and decreased biomass more than mesotrione alone. In fact, although mesotrione alone initially reduced centipedegrass photosystem II efficiency, an overall increase in efficiency was observed 28 d after treatment (DAT). Based on experiment 1, atrazine at 0.28 kg ai/ha was the maximum rate that could be applied to seedling centipedegrass when tank mixed with mesotrione. Experiment 2 evaluated atrazine at 0.28 kg/ha plus mesotrione at 0.03 to 0.28 kg/ha on centipedegrass field establishment. Although all atrazine plus mesotrione treatments reduced centipedegrass ground cover 28 DAT; no treatment reduced centipedegrass ground cover 49 DAT.
Ornamental and Row Crop Susceptibility to Flumioxazin in Overhead Irrigation Water
Authors: Mudge Christopher R. , Haller William T.
Published: March 2009

The effects of flumioxazin in irrigation water were evaluated on four row crop species (corn, cotton, soybean, and wheat) and three ornamental species (begonia, impatiens, and snapdragon). Plants were overhead irrigated one time with flumioxazin at concentrations of 0, 10, 25, 50, 100, 200, 400, 800, 1,600, and 3,200 µg ai/L in water equivalent to 1.27 cm. Ornamental plant tolerances on the basis of a 10% reduction in dry weight (effective concentration 10 [EC10]) were as follows: impatiens (40) < begonia (103) < snapdragon (7,024). The EC10values of flumioxazin on the basis of dry weight values for row crop species were wheat (35) < corn experiment 1 (53) < cotton (106) < corn experiment 2 (181) < soybean (193). EC10values for plant height were similar to values for plant dry weight for ornamental and crop species. Snapdragon was the only plant evaluated that was mature at the time of treatment; consequently, all other species were moderately to highly sensitive to irrigation water containing flumioxazin. These data show that flumioxazin can injure and kill immature ornamental and crop species within the potential maximum concentration of 400 µg/L; however, the very short half-life of this herbicide in water with pH 7.0 to 9.0 (ca. 16 h to 17 min) could result in less injury than suggested in this study.
Soybean Seeding Rate Effects on Weed Management
Authors: Arce Guillermo D. , Pedersen Palle , Hartzler Robert G.
Published: March 2009

Studies were conducted in 2005 and 2006 at three Iowa locations to determine the effect of soybean seeding rate and glyphosate application timing on weed management and grain yields in glyphosate-resistant soybean. End-of-season weed populations were affected by soybean seeding rate at only one location, with higher weed densities present in the lowest seeding rate when glyphosate was applied at the V2 soybean growth stage. Although weed populations were not consistently affected by soybean population, weed biomass present at soybean harvest was inversely related to soybean population. At the location with the highest weed populations, no single glyphosate application provided yields equivalent to the weed-free control. At the other locations, glyphosate application timing did not affect soybean yield. Lower soybean yields occurred with 240,000 seed/ha compared with 420,000 seed/ha at all locations and with 300,000 seed/ha at two locations.
Glyphosate-Resistant Waterhemp (Amaranthus rudis) Control and Economic Returns with Herbicide Programs in Soybean
Authors: Legleiter Travis R. , Bradley Kevin W. , Massey Raymond E.
Published: March 2009

Field experiments were conducted in Platte County, Missouri, during 2006 and 2007 to evaluate PRE, POST, and PRE followed by (fb) POST herbicide programs for the control of glyphosate-resistant waterhemp in soybean. All PRE fb POST treatments resulted in at least 66 and 70% control of glyphosate-resistant waterhemp in 2006 and 2007, respectively. Control of glyphosate-resistant waterhemp was less than 23% with lactofen and acifluorfen in 2006, but at least 64% in 2007. Variability in control likely resulted from differences in trial locations and a population of protoporphyrinogen oxidase (PPO)–resistant waterhemp at the Platte County site in 2006 compared with 2007. In both years, glyphosate resulted in less than 23% control of glyphosate-resistant waterhemp and provided the least control of all herbicide programs. Programs containing PRE herbicides resulted in waterhemp densities of less than 5 plants/m2, whereas the POST glyphosate treatment resulted in 38 to 70 plants/m2. Waterhemp seed production was reduced at least 78% in all PRE fb POST programs, from 55 to 71% in POST programs containing lactofen and acifluorfen and by only 21% in the POST glyphosate treatment. Soybean yields corresponded to the level of waterhemp control achieved in both years, with the lowest yields resulting from programs that provided poorest waterhemp control. PRE applications ofS-metolachlor plus metribuzin provided one of the highest net incomes in both years and resulted in $271 to $340/ha greater net income than the glyphosate-only treatment. Collectively, the results from these experiments illustrate the effectiveness of PRE herbicides for the control of glyphosate-resistant waterhemp in glyphosate-resistant soybean and the inconsistency of PPO-inhibiting herbicides or PPO-inhibiting herbicide combinations for the control of waterhemp populations with multiple resistance to glyphosate and PPO-inhibiting herbicides.
Barley and Rigid Ryegrass (Lolium rigidum) Competition is Influenced by Crop Cultivar and Density
Authors: Paynter Blakely H. , Hills Andrea L.
Published: March 2009

Western Australian growers are adopting no-tillage farming systems, which have a greater reliance on integrated weed management systems that include competitive cultivars, high seeding rates, strategic fertilizer placement, and narrow row spacing. At the same time, they are sowing more of their barley area to cultivars with a semidwarf habit. This study compared six two-row, spring malting barley cultivars with different morphological traits at two dates of planting and three crop densities, with nil-added and added rigid ryegrass at five sites. Four cultivars, ‘Buloke’, ‘Flagship’, ‘Hamelin’, and ‘Vlamingh’, had an erect early growth habit; the other two, ‘Baudin’ and ‘Gairdner’, had a prostrate, semidwarf early growth habit. Increasing the density of rigid ryegrass plants from 16 to 125 plants/m2decreased barley grain yield by reducing crop biomass production, tiller number, grain number, and harvest index. Average grain weight was also reduced at most sites. The impact of competition on grain yield varied across sites and cultivars, but did not interact with date of planting. Baudin, Flagship, and Hamelin were more competitive with rigid ryegrass than Buloke, Gairdner, and Vlamingh. Differences in competitiveness between cultivars did not appear to be strongly related to morphological traits that affect light interception such as canopy closure, plant height, and tiller number. Differences in cultivar competitiveness were cultivar-specific and not generic. Rigid ryegrass productivity (dry matter and tiller number) tended to be lower under the more competitive cultivars. Increasing barley plant density increased grain yield, and reduced both rigid ryegrass dry matter and tiller number. Barley density had a larger impact on rigid ryegrass productivity than crop cultivar. The impact of barley density on reducing rigid ryegrass tiller number was larger with the first planting date than the second, and higher in the added rigid ryegrass plots than the nil-added plots. This study highlights the importance of high barley seeding rate for the integrated management of rigid ryegrass.
Efficacy of Sodium Chloride Applications for Control of Goosegrass (Eleusine indica) in Seashore Paspalum Turf
Authors: Brosnan James T. , DeFrank Joseph , Woods Micah S. , Breeden Greg K.
Published: March 2009

Control of goosegrass is difficult in the pan-Pacific region. No herbicides are currently labeled for selective control of goosegrass in seashore paspalum turf, a species used regularly on golf courses throughout the tropics. Sequential granular applications of sodium chloride (99% sodium chloride, 1% sodium silicoaluminate, 83% 0.5 to 0.25 mm diam) at 488 kg/ha did not effectively (> 70%) control goosegrass in this study. Goosegrass injury following sequential granular applications of sodium chloride, at 488 kg/ha, subsided at 6 wk after initial treatment (WAIT). A single application of MSMA at 2.40 kg/ha plus metribuzin at 0.56 kg/ha provided 96 and 83% control of goosegrass 8 WAIT in 2007 and 2008, respectively. Sequential applications of MSMA plus metribuzin at lower rates yielded similar results. Applications of foramsulfuron did not effectively control (> 70%) goosegrass in this study, suggesting a possible tolerance to this treatment. Applications of MSMA plus metribuzin controlled goosegrass (> 70%), but induced phytotoxic injury to seashore paspalum turf. Additional research is needed to evaluate strategies for POST control of goosegrass in seashore paspalum turf that do not induce phytotoxic turfgrass injury after application.
Comparison of vacuum consolidation with surcharge load induced consolidation of a two-layer system
Authors: CHAI J.-C. , MATSUNAGA K. , SAKAI A. , HAYASHI S.
Published: March 2009

Laboratory consolidation tests for a two-layer soil system under oedometer conditions were conducted under both vacuum pressures and surcharge loads. The effects of the order of soil layers on the behaviour of vacuum consolidation of the two-layer soil system have been investigated by comparing vacuum pressure and surcharge load induced consolidations. Under one-way drainage conditions, for both a surcharge load and a vacuum pressure, the order of soil layers only influences the rate of consolidation but not the final settlement. When a layer with a relative lower value of hydraulic conductivity (k) is located immediately adjacent to the drainage boundary, the consolidation rate is slower. However, for vacuum pressure applied under two-way drainage conditions, the order of the soil layers not only influences the rate of consolidation but also the magnitude of settlement.
Modelling runoff in an urban catchment using Vflo™ and QPE
Authors: Adams R. , Rees P. L.
Published: March 2009

Real-time flood forecasting has benefited greatly by the application of physically based hydrological models and real-time rainfall data obtained from weather radar. An application of a distributed hydrological model (Vflo™) to an urban catchment using distributed rainfall data from Nexrad radar images illustrates some important issues. The benefits of using Nexrad data with pixels approximately 1 km2 as opposed to using a single raingauge located at the edge of the catchment are demonstrated through model simulation. It was also possible to improve the model results by developing a new conceptual model of the 10·25 km2 Harris Gully catchment (in Houston, Texas) and replacing an earlier model calibrated on the much larger Brays Bayou catchment. In the case of the Harris Gully catchment, flooding has been caused by several factors including heavy rainfall on the catchment exceeding the design capacity of the existing storm sewer system, and backwater effects caused by the larger Brays Bayou (which Harris Gully flows into) running at full capacity. Improving the existing flood forecasting system (FAS, the flood alert system) for Harris Gully is of high priority since the catchment contains the Texas Medical Center and the main campus of Rice University. It is planned to do this through the installation of a state-of-the-art NetRAD weather radar in the near future.
High-resolution precipitation estimates for hydrological uses
Authors: Harrison D. L. , Scovell R. W. , Kitchen M.
Published: March 2009

The use of precipitation estimates from weather radar for hydrological applications has been limited by the quantitative accuracy, reliability and resolution. The adoption of a more centralised approach to radar data processing, upgrades to telecommunications links and the installation of additional radars in the UK weather radar network have enabled some of these limitations to be addressed. The development of more flexible product generation software, which more fully exploits the resolution of the radar measured reflectivity, now provides for the mapping of precipitation on scales of 1 km and even below, thus approaching the resolution requirements for applications in urban hydrology. This paper describes the methods by which these high-resolution precipitation products are now generated. Illustrations of the products are given and their use in predicting flow using an urban drainage model is demonstrated. Issues affecting data quality, and the advantages and disadvantages of using radar products at high resolution are discussed.
Food-chain transfer of cadmium and zinc from contaminatedUrtica DioicatoHelix AspersaandLumbricus Terrestris
Authors: Sinnett Danielle E. , Hodson Mark E. , Hutchings Tony R.
Published: March 2009

The present study examines the potential of Urtica dioica as an ecologically relevant species for use in ecotoxicological testing. It is prevalent in degraded ecosystems and is a food source for invertebrates. Urtica dioica grown in hydroponic solutions containing from less than 0.003 to 5.7 mg Cd/L or from 0.02 to 41.9 mg Zn/L accumulated metals resulting in leaf tissue concentrations in the range of 0.10 to 24.9 mg Cd/kg or 22.5 to 2,772.0 mg Zn/kg. No toxicological effects were apparent except at the highest concentrations tested, suggesting that this species may be an important pathway for transfer of metals to primary plant consumers. Helix aspersa and Lumbricus terrestris were fed the Cd-and Zn-rich leaves of U. dioica for six and four weeks, respectively. Cadmium and Zn body load increased with increasing metal concentration in the leaves (p < 0.001). Ratios of invertebrate metal concentration to leaf metal concentration were in the range of 1:0.03 to 1:1.4 for Cd and 1:0.2 to 1:2.8 for Zn in H. aspersa and 1:0.002 to 1:3.9 for Cd and 1:0.2 to 1:8.8 for Zn in L. terrestris. Helix aspersa Cd and Zn tissue concentrations (15.5 and 1,220.2 mg/kg, respectively) were approximately threefold those in L. terrestris when both species were fed nettle leaves with concentrations of approximately 23 mg Cd/kg and 3,400 mg Zn/kg. Models demonstrate that L. terrestris Cd tissue concentrations (r2 = 0.74, p < 0.001) and H. aspersa Zn tissue concentrations (r2 = 0.69, p < 0.001) can be estimated from concentrations of Cd and Zn within the leaves of U. dioica and suggest that reasonably reproducible results can be obtained using these species for ecotoxicological testing.