bluuebunny/crossref_metadata_2025 huggingface dataset:
An Evaluation of Methods Used in Comparative Field Testing of Commensal Rodenticides
Authors: Daniel Ashton A , Jackson WB , McCumber JH
Published: March 2009

Comparative field testing of commensal rodenticides is defined as a side-by-side testing of two or more materials under similar environmental conditions. This differs from comparison of field test data, where information is obtained at different times or under different environmental field conditions.

Comparative testing provides valuable information concerning advantages and limitations of rodenticides, including experience with special uses. This is useful for control operators when planning strategies for chemical and other control techniques in the development of integrated pest management. Comparative testing also may provide information pertinent to labeling instructions.

The design of a comparative field test should permit an unbiased evaluation of the rodenticides. The test site should be relatively homogeneous: a group of similar buildings, several contiguous city blocks, or a building which can be divided into comparable units. The use of isolated areas would be ideal but not essential if precautions are taken to avoid or limit rodent movements between areas. Equivalent pest infestations in all areas, although desirable, also are not essential if the censusing techniques are sensitive to the relative density. Use of two or more censusing techniques is desirable to prevent method limitations from biasing the test results. This permits greater flexibility in data analysis should one of the census methods prove inappropriate or unmanageable.

The test should include a control group or population, if possible. This control area (population) can be an untreated area or, in the case of a warfarin-resistant rat or mouse population, an area treated with a warfarin bait. Use of a control provides baseline information on population patterns within the test environment.

Included for discussion are comparative tests on Norway rats (Rattus norvegicus) in urban habitats and tests on rural resistant house mouse (Mus musculus) infestations. Rodenticides in pelletized and meal formulations were utilized as place pack and bulk baits. Compounds utilized during these evaluations include warfarin (0.025% bait), bromadiolone (Maki) (0.005% bait), brodifacoum (Talon) (0.005% bait), pyriminy (DLP-787) (10% tracking powder), and bromethalin (EL-614) (0.005% bait).
Design and Evaluation Criteria for Development of Toxic Wicks for Rodent Control
Authors: Morris KD , Proctor RD , Kaukeinen DE
Published: March 2009

Research suggests the feasibility of using wicks to deliver toxicants for rodent control, with subsequent rodent ingestion of the toxicant through grooming. Such wicks may overcome disadvantages of more conventional control materials, such as toxic baits and tracking powders for such applications as sites with little space or access for conventional baiting, with attractive alternative food sources, or where potential hazard and contamination are of particular concern.

Several innovations for developing and evaluating toxic wicks for rodent control are described. These methods are devised to determine optimum wick systems based on considerations of outer device construction, wick configuration and composition, and the nature and concentration of the toxicant in the device. Further, the delivery system to the rodent in relation to rodent susceptibility and behavior, wick placement, longevity, and safety are explored. Although the techniques illustrated involve a brodifacoum-containing wick device for commensal house mouse control, similar considerations and test procedures would have application in developing other toxicants and wick devices for rodent control.
Field Methodology for Evaluating Rodenticide Efficacy
Authors: Spaulding SR , Jackson WB
Published: March 2009

Methodology utilized to evaluate the efficacy of the experimental rodenticide bromethalin is described. Test site selection and determination of appropriate census techniques for use in different situations were important to the success of the field trial program. The testing program was divided into the following phases: (1) familiarization period, (2) pretreatment census, (3) pretreatment lag phase, (4) treatment period, (5) posttreatment lag phase, (6) posttreatment census, and (7) snap-trapping. The computerized data handling system used for storage and retrieval of data generated in the field trial program is described. A combination of two or three of the following census techniques was used to evaluate rodent activity before and after toxicant treatment: (1) census feed consumption, (2) tracking activity, (3) burrow activity, (4) dropping counts, (5) live trapping, and (6) water consumption. Overall, percentage reductions in activity values were comparable among census techniques. Tracking activity values were lower than those of other techniques in several house mouse trials, indicating the sensitivity of this method for monitoring mouse activity. A representative Norway rat field trial is presented to illustrate data generated through utilization of the previously described methodology and testing program.
An Approach for Evaluating Food Container Resistance to Damage by Individual Norway Rats
Authors: Glahn JF , LaVoie GK
Published: March 2009

A test chamber incorporating a remotely triggered low-light level video camera and recorder is described for evaluating food container resistance to damage by Norway rats (Rattus norvegicus). Data presented on the actual gnawing times necessary for a rat to penetrate a standard container and behavioral patterns associated with penetration suggest that this approach is a reliable measure of container resistance. To account for variation in penetration times both within and among test animals, we present a simple damage resistance index for test containers using a three-day test series to compare penetration times of test containers with an average of the penetration times for two standard containers. The mean index values derived in this manner appear sufficiently sensitive and reliable to rate the relative resistance of test containers. Application of this testing apparatus and method is described, including its limitations and possible modifications.
Methods for Assessing Rat Damage to Growing Wheat in Bangladesh, with Examples of Applications
Authors: Sultana P , Brooks JE , Poché RM
Published: March 2009

Methods for assessing damage by the lesser bandicoot rat, Bandicota bengalensis, to growing wheat crops are described and compared with other methods. Damage was related to yield, density of wheat stems, agricultural practices, and the foraging range of the rodent species. Applications of the damage assessment are given for estimating the annual losses to growing wheat over several large wheat districts in Bangladesh, and uses of the assessment in evaluating the efficacy of rodenticides in field trials and farmer use of rodenticide treatments are shown.
An Evaluation of Visual Counts for Censusing Ground Squirrels
Authors: Fagerstone KA
Published: March 2009

Visual counts frequently are used to census ground squirrels before and after a control program. However, the precision of visual counts is not known. During 1979 and 1980 I compared visual counts of Richardson's ground squirrels (Spermophilus richardsonü elegans) with mark-recapture population estimates on a study area near Kremmling, Colo. There was no significant correlation between the population estimate generated over a five-day trapping period and the highest visual count on a particular day within that period (R = 0.42, P = 0.06). However, there was a significant correlation between the population estimate and the highest ground squirrel count during the five-day period (R = 0.65, P = 0.009). Therefore, if certain guidelines are followed, visual counts may be reliable indices of ground squirrel populations.
Criteria for the Selection and Development of Predacides
Authors: Savarie PJ , Connolly GE
Published: March 2009

Since 1940, the Denver Wildlife Research Center has been evaluating toxicants for the control of coyotes. These lethal agents for coyotes and other predators are commonly called predacides. This paper describes our current criteria for the selection and development of predacides. Efficacy standards under practical working conditions, human and environmental safety factors, and compliance with registration requirements established by the U.S. Environmental Protection Agency (EPA) under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) are important criteria. Most of the criteria were developed for chemicals that would be used in the livestock protection collar (toxic collar), but they also apply to other predacidal techniques such as single lethal dose baits and large baits.

The first criterion is that the chemical be toxic to coyotes, although tests on coyotes may be precluded for chemicals that are hazardous to humans. Of prime importance is that the chemical not be dermally toxic or carcinogenic. An antidote is highly desirable but not essential. A predacide should be tasteless and odorless so that it is well accepted and should be effective at low oral doses so that the amount used is not excessive and bulky. A predacide should be effective within 24 h so that predation can be stopped as soon as possible. Chemicals that are economical and commercially available are highly desirable. Residue levels in poisoned coyotes should not be toxic to scavengers. For livestock-borne devices such as the toxic collar, the toxicant should not leave harmful residues of chemical in sheep exposed to sublethal doses. The presence of such residues could prevent marketing of sheep that had worn toxic collars. If the sheep dies, residues in or on the sheep should not be toxic to scavengers. Selective toxicity to coyotes is desirable so that nontarget species will not be poisoned if they come in contact with the chemical. Last, the chemical should be registerable and fulfill requirements as set forth by regulatory agencies.
Evaluation and Control Implications of Behavior of Feral Dogs in Interior Alaska
Authors: Gipson PS
Published: March 2009

Feral dogs (Canis familiaris) were studied from August 1979 through December 1981 in interior Alaska. Study techniques included use of radio telemetry, tracking in snow, and direct observation. Data were obtained on feral dog life history, including home ranges, activity patterns, breeding activity, foraging behavior, and interactions with tame dogs, red foxes (Vulpes vulva), coyotes (C. latrans), and wolves (C. lupus). Study findings challenged the hypothesis that populations of feral dogs or of dog-coyote or dog-wolf hybrids will not survive in northern regions because they are generally less fit than native canids and have lowered survival of offspring. Adult feral dogs and their pups survived winter conditions and were commonly active when temperatures were between 29 and −30°C. On one occasion, pups and their mother foraged away from the den when temperatures were below −45°C. Interactions of feral dogs with man and damage to livestock and game animals were surveyed. Periodic attempts to reduce feral dog populations have been undertaken by local residents. The principal control measures they employed included shooting, trapping, snaring, and destruction of pups in dens. These control measures resulted in temporary local population suppression. Information determined from this study should be helpful in planning future control measures, if control is deemed appropriate.
Studies of Grain Boundary Cavitation by Small-Angle Neutron Scattering
Authors: Cabañas-Moreno JG , Yang MS , Weertman JR , Roth M , Zhang ZY , Wignall GD , Koehler WC
Published: March 2009

Small-angle neutron scattering has been used to study the process of fatigue-induced grain boundary cavitation in two model materials, pure copper and a Cu-7A1 alloy, fatigued at elevated temperature. Values have been obtained from the scattering data for void volume fraction, and number density of the voids and their size distribution, as a function of fatigue time. The growth rate of individual voids has been calculated and found to be in good agreement with a recent theory of fatigue-induced cavitation. Copper and copper-aluminum show opposite responses to the effect of fatigue temperature on cavitation. An increase in the temperature of fatigue produces an increase in the total void volume growth rate and the void nucleation rate in the case of copper, a decrease in copper-aluminum. The process of grain boundary cavitation is shown to be very sensitive to the movement of the grain boundaries. Grain boundary migration can cause cavitated boundaries to shed their voids into the matrix. The number and size distribution of cavities in a specimen appear to be related to the extent of grain growth which occurs during fatigue.
In Situ Indications of Ductility Evolution During High-Temperature Fatigue Testing with and without Hold Times
Authors: Rahka K , Laird C
Published: March 2009

It has been reported in the literature that high-temperature fatigue exposure initially leads to an increase in the subsequently measured creep ductility, whereas prolonged fatigue exposure lowers the creep ductility in low-alloy Cr-Mo-V-steel. In the work now being initially reported an aim has been to observe microstructural changes due to high-temperature strain-controlled fatigue exposure with or without hold times. The controlled strain was the principal (axial) strain. For test response variables, the load and diametral strain were measured. While the cycle-to-cycle flow stress was observed to decrease monotonically—that is, the material cyclically softened—, the diametral strain range initially increased and subsequently decreased. It is concluded from the similarity in behavior between the changes in post-fatigue creep ductility (lateral contraction at fracture, RA) and in situ diametral strain range that the in situ diametral strain range is a powerful means of observing ductility changes due to fatigue. The effect of hold time at the tensile limit of the cycle is to reduce the diametral strain range as a whole and to speed up the drop in diametral strain range after it passes its maximum value. The maximum is generally reached during the few tens of initial cycles. The subsequent exhaustion of ductility develops quite rapidly at first but then slows down until the onset of cracking eventually speeds up the ductility exhaustion rate. In all cases the diametral strain amplitude behaved in a more strongly changing manner than the flow stress, indicating more sensitivity to the microstructural damage than the drop in the flow stress.
Quantitative Measurement of Energy Associated with a Moving Fatigue Crack
Authors: Fine ME , Davidson DL
Published: March 2009

Energy must be supplied to accomplish the processes which occur in the plastic zone ahead of the crack during fatigue crack extension. This energy has been measured (1) by using foil strain gages (Ikeda, Izumi, and Fine), (2) from electron-channeling patterns (Davidson and Lankford), (3) by stereoimaging (Davidson and Lankford), and (4) from calorimetric measurement of the heat generated during crack propagation (Gross and Weertman). The experimental results to date are presented and discussed. Both the hysteretic and permanent plastic work have been measured by strain pages. The permanent plastic work and the stored energy from cyclic plastic work are negligible. The work done numerically equals the heat evolved. The crack propagation rate data fit an equation dC/dN = AΔK4/μσ'yU, where A is a universal constant, µ is the shear modulus, σ'y is the cyclic yield stress, and U is the energy per unit area of fatigue crack. The latter is a function of ΔK except when the exponent in the Paris equation is 4.
Effects of Impurity Segregation and Hydrogen on Intergranular Brittle Fracture in an Alloy Steel
Authors: Kameda J
Published: March 2009

Recent progress in the study of the effects of impurity segregation and hydrogen on intergranular embrittlement is reviewed. A method of measuring the intergranular fracture strength, σ*, as a function of the grain boundary concentration of metalloid elements (antimony, tin, and phosphorus) in a nickel-chromium steel is developed, using a combination of micromechanisms of intergranular failure and statistical analyses of impurity segregation. The observed embrittling potencies of elements of Groups IVA to VIA are rationalized in terms of a simple hypothesis deduced from the atomistic binding components in transition metals. The relationship of the microscopic toughness, kIc, (derived from the foregoing measurements of σ*) to the fracture toughness, KIc, is discussed in terms of a proposed model for stress-gradient control of brittle fracture. The author has found that the measurement of KIc gives a distorted view of the progress of intergranular embrittlement. In addition, the mechanism of intergranular cracking is studied in terms of the combined effects of the previously segregated impurity and the hydrogen absorbed during tests. This study shows that the presence of hydrogen produces a profound intergranular weakening when the grain boundaries contain even a small amount of a segregated embrittling element. A dynamic decohesion model, which takes into account an atomistic mechanism of local hydrogen accumulation adjacent to a moving microcrack tip, is proposed to rationalize the pronounced effect of impurity segregation on hydrogen-induced intergranular cracking.
Research Toward New Alloys for Generator Retaining Rings
Authors: Morris JW , Chang KM
Published: March 2009

The research reported here was undertaken to develop an alloy suitable for use in the retaining rings of two-pole electrical generators which would have three key properties: (1) a yield strength of 1380 MPa (200 ksi) or greater with good residual toughness, (2) resistance to hydrogen embrittlement and stress-corrosion cracking, and (3) processability through heat treatment after hot forming, to avoid the necessity of cold forming of the ring. The principal alloy developed during the course of this work was an iron-based superalloy, designated EPRI-T, which has the nominal composition Fe-34.5Ni-5Cr-3Ti-3Ta-0.5Al-1.0Mo-0.3V-0.01B. The alloy is strengthened through the formation of cubic γ′ precipitates of the composition Ni3(Ti,Ta,Al). When given appropriate aging treatment from the as-forged condition, the alloy achieves yield strnegth in excess of 1380 MPa (200 ksi) with good residual toughness and promising resistance to cracking in gaseous hydrogen and salt water. The composition and processing of the alloy are the result of sequential metallurgical development, the steps of which are described in the body of the paper. The alloy was chosen from a class of iron-based superalloys to achieve high strength in thick sections while maintaining reasonable costs, melting practice, and hot formability. The nickel content of the alloy was adjusted to insure that the alloy would be paramagnetic austenite after the aging reaction to form the Ni3X strengthening precipitates. Tantalum was included among the γ′-forming elements to increase the lattice mismatch of the precipitate and improve alloy strength. Chromium was added to the composition to stabilize the austenite phase and eliminate stress-corrosion cracking susceptibility due to martensitic transformation of the austenite. The Mo-V-B group was included to inhibit intergranular precipitation of the equilibrium η phase and hence suppress a tendency toward intergranular fracture in the alloy.
Application of Bainite and Ferrite-Martensite Structure for High-Strength Heavy-Gage Linepipe
Authors: Takechi H , Matsuda H , Tamehiro H , Ohashi M , Nakasugi H
Published: March 2009

It is essential for linepipe used in severe environments, such as cold regions and the deep sea, to have a good balance of strength, toughness, and weldability. To improve these properties conspicuously, ultralow carbon bainitic (ULCB) steel was developed. ULCB steel is well suited for Arctic linepipe up to American Petroleum Institute (API) Grade X80 because of its excellent girth weldability and high strength. The low-temperature toughness in the weld heat-affected zone (HAZ) is, however, not sufficient for use below −45 °C because of the addition of columbium and boron. Therefore, another kind of linepipe steel must be developed for very low temperature use, such as in heavy wall pump stationing pipe. It is extremely difficult, however, to attain high strength and high toughness by conventional controlled-rolling practice without the use of columbium and boron.

To solve this difficult problem, a new chemical composition and controlled-rolling method have been developed. The typical chemical composition is 0.05C-1.6Mn-0.45Ni-0.25Mo-0.01Ti for API X65 grade steel, and the chief characteristic of controlled rolling is a very low slab reheating temperature (about 960 °C) and rolling in the austeniteferrite region. The microstructure of this steel comprises a mixture of fine elongated martensite and deformed and nondeformed ferrite, and shows the dual-phase structure.

In this paper, the effects of microalloying elements and processing parameters on the mechanical properties of UCLB and ferrite-martensite dual-phase steels are discussed, and the results of actual production tests are also presented.
Effect of Microstructure on Sulfide-Stress-Cracking Resistance of High-Strength Casing Steels
Authors: Sponseller DL , Garber R , Straatmann JA
Published: March 2009

The effect of microstructure on the sulfide-stress-cracking (SSC) resistance of developmental high-strength Cr-Mo and Mn-Mo casing steels has been evaluated. Results obtained in many investigations, some previously published and some new, conducted at this laboratory over the past decade are presented and discussed in the light of published results on hydrogen-assisted fracture of steels from other laboratories. The processing variables examined include hot working, austenitizing conditions, quench rate, tempering temperature, and cooling rate from the tempering temperature. An analysis of the data reveals that SSC resistance is aided by refinement of the austenite grain size, by the achievement of a fully martensitic microstructure during hardening, by increasing the tempering temperature, and by water quenching after tempering. The SSC resistance is degraded severely by tempering just above the lower critical (Ac1) temperature and then water quenching. Cast structures are comparable to wrought structures in SSC resistance.
Improvement of Submerged-Arc Weld Heat-Affected Zone Toughness by Titanium Additions to Linepipe Steels
Authors: McCutcheon DB , McGrath JT , Godden MJ , Ruddle GE , Weatherly G , Houghton DC
Published: March 2009

The effect of titanium additions on the base plate properties and coarsegrained heat-affected zone (CGHAZ) toughness of a partially acicular ferrite linepipe steel has been studied using laboratory melts. The heats were made with titanium levels between 0 and 0.039 weight percent, and were chill cast using cooling rates similar to those in commercial slab casting. The slabs were controlled rolled to 15-mm plate, and the CGHAZ grain size and toughness were evaluated using both double-pass submerged-arc welds (≈2 kJ/mm heat input) and simulated CGHAZ coupons.

Titanium additions between 0.005 and 0.011 weight percent restricted austenite grain coarsening during both slab reheating and thermal cycles of the weld heat-affected zone (HAZ). This improved the plate Charpy fracture appearance transition temperature and the CGHAZ toughness of simulated weld HAZs, measured by using both crack opening displacement and instrumented impact tests. Higher titanium additions (0.015 to 0.039 weight percent) at high titanium/nitrogen ratios (3.00 to 4.6) exhibited improved grain size control in comparison with the base chemistry heats, but no significant improvement in CGHAZ toughness.

The precipitate size distribution and chemistry in the as-cast, as-rolled, and welded conditions have been characterized to assess their effect on grain coarsening.
The Formulation Chemist in an Emergency Response System
Authors: Wright JF
Published: March 2009

A formulation chemist strives to develop formulations of pesticides with stable chemical and physical integrity. Situations may arise in which one has to understand the what and why of formulation chemistry in order to destroy the chemical and physical stability of the formulated product. This paper will demonstrate how the formulation chemist's input is an integral part of an emergency response system.
Introduction to Granular Carriers, Granular Pesticide Formulations, and Processing
Authors: Sawyer EW
Published: March 2009

Granular pesticides are grains or pellets containing pesticidal toxicants diluted to the desired concentration by mixing with other inert and functional ingredients. They are processed to give fairly close particle size distributions with the objective of facilitating application at optimum rates. Formulations and preparations of granular pesticides vary widely but the preparation method generally falls into one of four categories: (1) impregnating on presized sorptive carriers, (2) sticking on presized carriers, (3) formulating and postforming, as in extrusion and agglomeration, and (4) postforming on a core. In addition to toxicants, carriers, binders, deactivators, dispersants, wetting agents, surfactants, core materials, and solvents are employed. Historically the commercial success of a toxicant has depended on the forms that are available for toxicant delivery. The use of granular formulations followed on the heels of emulsion concentrates, wettable powders, and dusts to achieve certain application characteristics not available in the other forms—primarily, the ability to deliver the toxicant to a desired point. Granular pesticides can be designed to penetrate foliage, lodge in certain positions in plants, sink in water (and then disintegrate or release the toxicant, or both), and minimize drift and dusting. Granular pesticides were defined at one time as granules of a size coarser than 100 mesh—that is, 60/90, 30/60, or 8/16. Currently the designation has been extended to include microgranules of sizes such as 100/200 mesh.
Available Granular Carriers—Properties and General Processing Methods
Authors: Ross HW
Published: March 2009

Inert carriers are generally either inorganic minerals or botanical materials. These carriers can be divided further into granules and dust. The most popular granular carriers are the clay minerals attapulgite, montmorillonite, and vermiculite. The important botanical carriers are granular corncob and granular walnut shells.

Granular carriers can be generally described as having a mesh range of between 4 and 80 mesh. The standard sizes for clay are 8/16, 16/30, 25/50, and 30/60. Corncobs standard sizes are 8/14, 10/14, 10/20, 14/20, and 20/40.

The major producers of clay granulars carriers include Engelhard, Excel Minerals, Floridin, Lowe's, Inc., and Oil Dri. Corncob is produced in the Midwest by the Andersons, Coeval, Inc., and Mount Pulaski Products. Sand is produced by PPG Industries, Inc.

The general processing of clay follows the following sequence: (a) overburden removal, (b) mining, (c) grinding, (d) drying, (e) sizing, (f) high-temperature heating, (g) sizing, and (h) packaging and shipping.

Although this discussion may highlight only a few of the granular carriers and companies available, the intent is to introduce the reader to the granular marketplace and processing.
Granular Application Equipment—The State of the Art and Current Problems
Authors: Johnson RR
Published: March 2009

This discussion focuses on granular application equipment purchased and used by the farmer. Often this equipment is part of a planter or seeder but may be separate or combined with other implements. Insecticide applicators are the most popular granular attachment on row crop planters, followed in order by fertilizer and herbicide attachments. Fertilizer is the most popular granule used with small grain seeders, but herbicide and insecticides are also occasionally applied. A granular applicator must meter, deliver, and distribute the chemical. In some cases, soil incorporation is also required. Granules are usually metered either through a gravity-fed metering orifice or through a positive metering device in which a constant granule volume is metered by means of a rotor. The granule is then delivered to a target location by means of gravity or pneumatic pressure. In some cases, such as with insecticides, several alternative distribution methods and sites must be provided. These include application in the seed furrow or a broadcast band over the row that either remains on the soil surface or is incorporated into the soil profile.

Engineering decisions interact with physical and chemical properties of granular chemicals. Uniform metering is dependent upon careful control of factors such as particle size, bulk density, flowability, and caking susceptibility. Factors such as granule crushing strength, abrasiveness, and impact resistance affect the vigor with which mechanical systems can be designed to handle and deliver granules. The hygroscopic and corrosive properties of granules affect maintenance procedures and durability of a given application system. Future customers will demand and deserve improved granule application systems. Interdisciplinary cooperation can assist in targeting realistic areas to improve the ease, safety, and efficiency of chemical granule use.
Field Studies Monitoring Worker Exposure to Pesticides
Authors: Lavy TL , Mattice JD , Flynn RR
Published: March 2009

These studies were conducted to collect data on pesticide exposure levels acquired by applicators during typical spray operations. This information should complement toxicological data. Measurements from workers engaged in routine forestry operations were made for crews spraying two phenoxy herbicides, 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) and 2,4-dichlorophenoxyacetic acid (2,4-D). In less extensive studies, exposures to mixers and applicators of o-ethyl-o-4-nitrophenyl phenylphosphonothioate (EPN) in cotton fields and paraquat in grape vineyards were evaluated. Levels of the pesticides were measured in the breathing zone of workers, on patches attached to workers' clothing, and from urine excreted during and after spray operations. These methods of evaluation showed that workers in these spray operations received some exposure to these pesticides, but levels of exposure in all tests were well below any amounts shown to be toxic to laboratory animals in toxicological studies
Spray Characteristics of Rotary Atomizers
Authors: Bode LE , Butler BJ
Published: March 2009

Evaluations of the spray characteristics of a new atomizer (Micromax) indicate that rotary atomizers used on tractor-mounted sprayers have the potential to apply agricultural pesticides effectively. Operating the units at the spacing, height, and tilt angle that provides double to triple overlap of the spray output results in acceptable distribution patterns over a range of disk speeds and flow rates. The droplet spectrum produced by the Micromax is much narrower than the spectrum produced by conventional hydraulic nozzles, and the median size generated is related to the speed of the disk. Spray droplets from the Micromax tend to move off the swath and deposit in the first few metres downwind much more than those from flat fan sprays. At distances greater than 10 to 20 m downwind, the deposits were no different from those from a flat fan spray.
Laboratory and Field Characterization of Sulphlex as a Paving Binder
Authors: Kandhal PS , Mellott DB , Hoffman GL
Published: March 2009

Plasticized sulfur (Sulphlex) binders have been developed by the Southwest Research Institute (SWRI) in Texas as a total replacement for asphalt. The Pennsylvania Department of Transportation constructed an experimental pavement in October 1980 using Sulphlex 233-A binder. This study consists of laboratory and field characterization of Sulphlex in comparison to a conventional asphalt cement (AC-20).

Basic mix properties (such as, tensile strength, stiffness modulus, resilient modulus of elasticity, Marshall stability, etc.) were determined encompassing a rather wide range of pavement service temperatures: from −29 to 60°C (−20 to 140°F). The mix resistance to moisture-induced damage was also evaluated. The construction and field performance of the Sulphlex pavement have been described.

The tensile strength and stiffness modulus of the Sulphlex mix were determined to be significantly higher than the asphalt mix at temperatures lower than 16°C (60°F). The stiffness moduli data indicate that the Sulphlex mix is likely to be more prone to low temperature, nonload associated pavement cracking. The use of Sulphlex appears more promising in thick pavement layers, such as black base. Future formulations of Sulphlex binder should be aimed to lower the temperature susceptibility characteristics.
Damage and Failure in Carbon-Fiber-Reinforced Epoxy Resin
Authors: Bunsell AR , Laroche D , Valentin D
Published: March 2009

A model of failure in simple carbon-fiber-reinforced epoxy resin plate specimens is proposed which, it has been shown, can be applied to certain filament wound structures to calculate minimum expected lifetimes under steady loading conditions. The theoretical approach is based on the fiber-bundle-chain, weakest-link model, which has been extended to include the effects of the viscoelastic properties of the matrix. The use of the acoustic emission technique has allowed the development of internal damage to be monitored during steady loading conditions, and these experimental results were seen to support the theoretical model that is proposed.
Distribution of Absorbed Moisture in Graphite/Epoxy Laminates After Real-Time Environmental Cycling
Authors: Whiteside JB , DeIasi RJ , Schulte RL
Published: March 2009

Graphite/epoxy laminate specimens were selected from a previous study which included exposure to temperate and tropical aircraft ground storage environments with weekly supersonic flight temperature profiles. After drying and reexposure with heavy water vapor, nuclear reaction analysis was used to measure the distributions of absorbed moisture in sectioned specimens. The effects of thermal spikes on the distributions and comparisons with a history-dependent diffusion model are described.
Thermal Aging of Graphite/Polyimide Composites
Authors: Nelson JB
Published: March 2009

Celion® 6000/PMR-15, Celion 6000/LARC-160, and Celion 6000/RK-99 graphite/polyimides were aged in circulating air ovens at temperatures of 202, 232, 260, and 288°C for various times up to 15 000 h. Three unidirectional specimens were studied: short-beam-shear (SBS), flexure, and 153-mm square panels. The interior region of the square panels exhibited little or no property degradation. Based on the individually aged SBS specimen results, the relative thermal-oxidative stability from highest to lowest is as follows: PMR-15, LARC-160, RK-99. Celion 6000/PMR-15 and Celion 6000/LARC-160 laminates retained at least 80% of their initial flexural strengths for the duration of aging at each temperature. Celion 6000/RK-99 laminates exhibited a 20 to 50% loss of flexural strength at all aging temperatures. All three graphite/polyimide (Gr/PI) laminate materials degraded preferentially at the specimen edge perpendicular to the fibers.
Load Sequence Effects on Graphite/Epoxy [±35]2s Laminates
Authors: Yang JN , Jones DL
Published: March 2009

The effect of load sequence on the fatigue behavior of composite materials is contributed by (1) the difference in residual strength when fatigue fracture occurs, referred to as the boundary effect, and (2) the material memory effect with respect to previously experienced loads. A theoretical fatigue model previously developed by the authors is generalized herein to include the memory effect. The present model permits isolation of the memory effect from the boundary effect, thus the extent of the memory effect can be identified using residual strength test results under dual-level fatigue loadings. An experimental test program using graphite/epoxy [±35]2s laminates under high-low and low-high load sequences has been conducted to generate statistical residual strength data. It is shown that the material memory effect does exist for Gr/E [±35]2s laminates, as predicted by the model. The correlation between the test results and the theoretical predictions of the median residual strength and the expected percentage of fatigue failures under dual loading is very good. However, the statistical dispersion of the residual strength test results is much smaller than that of the static ultimate strength and that predicted by the model.
Irradiation Embrittlement of Pressure Vessel Steels: A Review of Activities in France
Authors: Petrequin P
Published: March 2009

Research on irradiation embrittlement in modern pressure vessel steels was initiated at the French Atomic Energy Commission ten years ago. During this period many steels and welds were irradiated in the Triton and Siloe reactors; research was undertaken both independently and within the framework of research programs coordinated by the International Atomic Energy Agency.

Mainly through tests of tensile and Charpy impact properties, the effects of chemical composition were studied, confirming the influence of copper and phosphorus and uncovering the surprisingly detrimental effect of nickel content. At the same time, new fracture mechanics testing procedures for irradiated materials were developed.

Today the major part of these programs is complete and future activities will probably be reduced on pressure vessel steels. The main topics for forthcoming studies are the effect of flux or irradiation rate on embrittlement and elastic-plastic fracture mechanics. A review of past activities and a preview of forthcoming research is given.

During the period covered by these studies, many pressurized water reactors were built in France that are now starting to operate, with each reactor containing irradiation surveillance capsules. This important program, which is described in the second part of the paper, will lead in the next ten years to an increased knowledge of radiation embrittlement on a more statistical basis, taking into account results obtained on a reference plate.
Specific Problems of Reactor Pressure Vessels Related to Irradiation Effects
Authors: Kussmaul K
Published: March 2009

The structural integrity of pressure vessels of light-water reactors is decisively controlled by the ductility of the vessel material. Layout and design principles as well as the chemical composition of the materials have been optimized for new plants as redundant measures to assure sufficient toughness during the whole lifetime history, an approach termed the Basis Safety Concept.

Adequate measures had to be taken to sustain the necessary safety margin in two older vessels that did not meet these advanced requirements. The necessary safety has been achieved by changing the core configuration to reduce the end-of-life fluence and thus limit the loss of toughness, and setting pressure and temperature limits on the heat-up and cool-down procedure to assure the load path, as well as by instituting an enhanced nondestructive evaluation program, especially on the joint weld of the belt line region, as a basis for fracture mechanics analysis.

Apart from surveillance and plant-specific irradiation programs, additional research and development programs are being performed to investigate irradiation damage by means of linear elastic and elastic-plastic fracture mechanics.
Survey of Utility Experience with Reactor Vessel Surveillance
Authors: Rothstein S
Published: March 2009

Changes in upper shelf energies and in transition temperatures of reactor vessel steels and weld metals, as reported by utilities, appear to be less than those currently predicted, and do not appear to be simply a function of fluence. Other possible contributing factors are suggested, as is expanded analysis of surveillance specimens.
Assessing Steady-State Neutron Exposure Effects Through Analyses of Reactor Vessel Surveillance Data
Authors: Mager TR , Martson TU , Yanichko SE
Published: March 2009

An investigation of steady-state radiation embrittlement of reactor vessels, which consists of surveillance capsule supplemental testing and mechanistic studies, is being conducted by the Westinghouse Electric Corporation for the Electric Power Research Institute. A summary of the increases in the 41-J (30-ft · lb) transition temperature exhibited by submerged arc weld material contained in eight supplemental surveillance capsules included in this investigation is presented. The data indicate that radiation damage for high-copper submerged arc welds does not saturate but does tend to show a very low rate of embrittlement at neutron fluences greater than ∼1 × 1019 n/cm2. The data also indicate that radiation damage predictions based on U.S. Nuclear Regulatory Guide 1.99, Revision 1, are not realistic for fluences greater than ∼1 × 1019 n/cm2, for most pressure vessel steels.
Problems in the Evaluation of Reactor Vessel Surveillance Capsules
Authors: Perrin JS
Published: March 2009

Commercial PWR and BWR power reactors in the United States each contain a series of pressure vessel steel surveillance capsules. These capsules typically contain neutron dosimeters, thermal monitors, Charpy V-notch impact specimens, and tension specimens. These capsules are periodically removed during the life of a reactor and evaluated to determine the effect of radiation on the pressure vessel steel. The pressure-temperature operating curves for the plant are adjusted as necessary by using the surveillance capsule results.

Much valuable information has been obtained from pressure vessel surveillance capsules. There are, however, numerous problems which have been encountered during the examination of these capsules. These problems could lead to a decrease in the amount of useful information obtained from a capsule. Areas in which problems have been observed include the overall surveillance program, capsule design and construction, specimen preparation and documentation, specimen testing and evaluation, and reporting.

Problems typical of those which have been observed are presented. In addition, recommendations for prevention of these problems are made.
Laser-Excited Fluorescence, Photoacoustic, and Photoionization Detection of Polyaromatic Hydrocarbons and Drugs
Authors: Winefordner JD , Voigtman E
Published: March 2009

Methods of enhancing the spectral selectivity for identification and quantitation of molecules in complex systems, such as polynuclear aromatic hydrocarbons (PAHs) in environmental samples or drugs in biological materials, are mentioned. The major emphasis concerns the description of the instrumentation and analytical figures of merit for a three-mode cuvette and a three-mode flow cell detection system based upon fluorescence, photoacoustic, and photoionization detection. The instrumental system consisting of a laser (nitrogen [N2] laser or N2-dye laser), the cell assembly, and the detection system is briefly described for all three modes for each type of cell. Limits of detection for the three modes are given and compared for several selected molecules. A model five-compound mixture is separated by high-performance liquid chromatography (HPLC) and detected with the three-mode flow detector. The mechanism of the photoionization detection is briefly discussed.
Selective Spectrometric Analysis by Laser-Induced Matrix Isolation Fluorometry
Authors: Conrad VB , Gore RR , Hammons JL , Maple JR , Perry MB , Wehry EL
Published: March 2009

The techniques of laser-induced matrix isolation fluorescence spectrometry and their application to identification and quantification of individual organic compounds (especially polycyclic aromatic hydrocarbons) in complex mixtures are described. Applications of Shpol'skii matrices, site-selection techniques, and time-resolved measurement of fluorescence to the matrix-isolation fluorometric characterization of complex mixtures are discussed. The need to use laser excitation of fluorescence to exploit fully the analytical selectivity offered by use of cryogenic specimen matrices is stressed.
Signal-to-Noise Considerations in Fluctuation Analysis Spectroscopic Techniques
Authors: Michael Ramsey J , Hieftje GM
Published: March 2009

It is possible to determine fluorescence lifetimes from the frequency response of a fluorophore as well as from its time response. Various schemes for measuring such a response curve are illustrated and include the use of sources whose intensity is modulated at single, swept frequencies, at several frequencies simultaneously, or over a broad, continuous band of frequencies. Detection methods that are considered include a single broad-frequency-response device, one that is swept, and another that hops from one modulated frequency to another. Signal-to-noise (S/N) expressions are derived for each combination of source and detector and conclusions are drawn from comparison of the S/N expressions. From these considerations and the availability of existing sources for use in time-resolved fluorometry, the most attractive approaches employ a source modulated at several frequencies simultaneously, each of which is monitored by its own tuned detector, or a sinuosidally modulated source that is swept synchronously with a tuned detector.
Variability of the Precipitation Process in Time and Space
Authors: Landsberg HE
Published: March 2009

The spatial and temporal distribution of precipitation as well as its quantity is highly variable. The coefficient of variation is a function of total annual amount. The smaller the total precipitation, the greater the variability. Sampling procedures are very deficient. The small orifices of gages cause sizeable errors. Differences in amounts collected even by closely spaced gages can be very large, especially in summer. Time series of neighboring gages as little as 5 km apart may have correlations of less than 0.5. In rolling and mountainous terrain differences in single rain events can be tremendous. This will affect the dilution of aerosols that are washed out.

Essential parameters are generally not measured. Principal among these are drop or flake diameters. These will affect both the dilution of the nuclei material and the efficiency of washout of aerosols. The number and nature of the cloud condensation nuclei are only observed in special projects. Drop sizes will change during single rain events, and the washout process will be strongly affected by the duration of precipitation events. Very few records exist of electrical charges on precipitation elements. These may have a fairly substantial influence on aerosol collection.

All of these characteristics have an influence on precipitation chemistry. They will affect the choice of sampling equipment and the sampling frequency. Notable differences exist between liquid and frozen precipitation, and information must be available about various forms of precipitation for proper interpretation. The chemical nature of the condensation nuclei for cloud formation, ultimately ending up in liquid rain, is different from the freezing nuclei involved in solid precipitation. And in many instances rain may start out as snow, melting on its way down. In all instances, whatever chemical material is dissolved or suspended in precipitation is a mixture of both the nuclei necessary for condensation or sublimation and aerosol washed out below the cloud level, and gases incorporated into precipitation either in or below the cloud.

The possibility of further chemical action among various components of advective and intercepted material makes it advisable to do any analysis as promptly as possible, preferably during the precipitation event.