bluuebunny/crossref_metadata_2025 huggingface dataset:
Adenosine Triphosphate and Guanosine Triphosphate Determinations in Intertidal Sediments
Authors: Karl DM
Published: March 2009

Measurements were made of the spatial distributions of adenosine triphosphate (ATP) on a variety of sandy beaches. Samples were collected during ebb flow and extracted in the field using cold sulfuric acid and ethylenediamine tetraacetate (EDTA); the neutralized extracts were immediately frozen for subsequent analyses. ATP was measured using the firefly bioluminescent reaction; however, during these investigations, a disparity was observed between the concentrations of ATP that were calculated from peak height and integrated light flux determinations. Integral measurements were consistently higher. Examination of the kinetics of the light emission reaction revealed an altered pattern of reactivity (relative to ATP standards) for nearly all of the sediment extracts. Thin-layer chromatographic separation procedures indicated that the sediment extracts contained additional nucleotide triphosphates (that is, GTP, UTP) at levels high enough to significantly interfere with quantitative ATP determinations. A technique was devised to eliminate this altered kinetic pattern in order to calculate true ATP levels. Additional methods were developed for the quantitative determination of guanosine triphosphate (GTP) using a nucleoside diphosphate kinase-firefly luciferase coupled reaction. The role of GTP in microbial metabolism, especially in the process of protein synthesis, results in an increase in the [GTP]/[ATP] ratio as a function of increasing growth rate. The measurement of [GTP]/[ATP] ratios in cell extracts may be useful for determining the metabolic states and rates of growth of microbial populations in nature.
Evaluation of the Most Probable Number Technique for the Enumeration of Fecal Coliforms and Pseudomonas aeruginosa in Sediment
Authors: Seyfried PL , Owen ARG
Published: March 2009

This study was designed to demonstrate the magnitude of the bias of the most probable number (MPN) test when applied to sediment. Sterile sediment samples were inoculated with fecal coliforms or Pseudomonas aeruginosa organisms, and recovery by MPN and plate count procedures was compared. The five-tube MPN estimates fluctuated between 43 percent above and 65 percent below the plate count when tests were performed with a 1:10 dilution of sediment inoculated with fecal coliforms. A 1:100 dilution of sediment produced an under-estimation in the counts of 86 percent. Analysis of the MPN expression for P. aeruginosa in sediment showed that with a 1:10 dilution, the numbers could vary from 39 to 98 percent below the plate count. The average underestimation for the 1:100 dilution was 90 percent. These results showed that, unlike water samples, which may have an 18 percent bias on the high side of the “true” population, sediment samples analyzed by the common 5-5-5 tube MPN technique yield a significant underestimation of the actual bacterial count.
Application of the 14C Organic Mineralization Technique to Marine Sediments
Authors: Litchfield CD , Devanas MA , Zindulis J , Carty CE , Nakas JP , Martin EL
Published: March 2009

This research was designed to demonstrate the usefulness of the heterotrophic mineralization technique in marine sediments and to assess the temporal and spatial heterogeneity of the marine sedimentary microbial population. To do this, adaptation of the mineralization procedures using [14C]urea and [U-14C]-L-aspartic acid was made. Exact details outlining procedures, replicates, substrate concentration, incubation conditions, etc. are described. The turnover times and maximal uptake velocity (Vmax) of substrate utilization as well as the total colony-forming units (CFU) on various media were all calculated according to standard procedures.

Temporal heterogeneity was examined during two cruises in August 1975 and August 1976 by repeated sampling at one or more stations during a 24- to 48-h cycle. From the measured parameters, there appears to be no significant diel periodicity in either the level of microbial activity or in the CFU. Calculated values for turnover times generally showed less variation than did the values for maximal uptake velocities.

Spatial heterogeneity in the sediments was evaluated using a multiple corer, which took four cores within 1 m2. Although slight variations in the absolute activity levels do exist within a station, they do not appear to be significant at the p = 0.1 level. Interstation variability is significant at p = 0.1. At the continuously reoccupied station, August 1975, close correlation between the numbers of CFU on selective media and the utilization of that 14C-labeled substrate indicated that the technique is indeed measuring microbial activity. Therefore, it is possible to use the 14C heterotrophic mineralizaion method in marine sediments, provided replication and sufficient controls are included. Within a designated station, the rather large sample size required obscures any microheterogeneity and provides an index of the level of microbial heterotrophic activity.
Effects of Metallurgical and Mechanical Factors on Charpy Impact Toughness of Extra-Low Interstitial Ferritic Stainless Steels
Authors: Ohashi N , Ono Y , Kinoshita N , Yoshioka K
Published: March 2009

The effects of precipitates, grain size, plate thickness, and notch sharpness on the Charpy impact toughness of extra-low interstitial 18Cr-2Mo, 26Cr-1Mo, and 29Cr-2Mo steels were investigated.

The steels exhibit good toughness in the solution-treated condition at 1000 to 1200°C and subsequently in the 2-mm V-notched condition. If the steels are subjected to fatigue cracks or brittle weld cracks, their transition temperatures increase and their shelf energies decrease.

When the steels are slowly cooled from the solution temperatures or reheated at intermediate temperatures, 700 to 900°C, after solution treatments, precipitation of second phases occurs, such as Laves phase in 18Cr-2Mo steel and sigma phase in 26Cr-1Mo and 29Cr-2Mo steels. The steels are embrittled by these precipitates and behave very similarly to the solution-treated specimens, having sharp notches such as fatigue cracks or brittle weld cracks.

A decrease in grain size or thickness is beneficial in lowering the transition temperatures of solution-treated and 2-mm V-notched specimens. This effect, however, decreases, when the specimens have brittle weld cracks.

These test results suggest that the solution-treated steels have good resistance to brittle fracture initiation and poor resistance to brittle crack propagation. Precipitation of second phases assists mainly crack initiation but also crack propagation to a lesser extent.
Development of a Low-Chromium Stainless Steel for Structural Application
Authors: Eckenrod JJ , Kovach CW
Published: March 2009

A new stainless steel is described which provides a good combination of mechanical properties and corrosion resistance for structural applications where welding is required. Development of this steel was based upon utilizing a 12 percent chromium, 0.85 percent nickel chemical composition which produces a tough, fine-grain size, ferrite-carbide microstructure in the mill-annealed condition. When welded with austenitic filler metal, a martensitic heat-affected zone microstructure is produced which also has good toughness resulting from its low-carbon nickel martensite composition. Data are given illustrating the composition balance and mill processing required to achieve these properties for this steel. The alloy has seen application in cargo container and mass transit vehicle structurals where good toughness, strength and corrosion resistance are required in the base metal and welds.
885°F Embrittlement in 12Cr Steel Distillation Column Tray
Authors: Creamer EL
Published: March 2009

A crude distillation column tray, fabricated supposedly from Type 410 stainless steel, failed in an extremely brittle manner after exposure to conditions which could induce 474°C (885°F) embrittlement. An investigation confirmed that the tray had experienced 474°C (885°F) embrittlement. Although the material met, according to analysis, Type 410 stainless steel composition requirements, it also contained a significant concentration of titanium, raising the suspicion that the alloy was Type 409 stainless steel. Results of the investigation tend to reinforce the concept advanced by others that titanium promotes 474°C (885°F) embrittlement in the straight chromium steels. Additional work is required to define the chromium and titanium levels which can lead to embrittlement.
Impact Properties of Fe-13Cr Thick Plate
Authors: Mintz B , Arrowsmith JM
Published: March 2009

The impact properties of an Fe-13Cr ferritic stainless steel at gages of 250 and 125 mm have been examined. Because these steels have notoriously coarse grain sizes, it is found that, on hot-rolling to thick plate, poor impact properties are often developed. Because only partial transformation to austenite is achieved on heat-treatment, it is not possible to refine the ferritic grain size and so improve impact performance. It has been found, however, that simple heat treatments can refine the grain boundary carbides and this action gives rise to as much as a 60 deg C fall in transition temperature. The various heat treatments given to the plates after hot-rolling are discussed and their impact properties compared with those obtained in the hot-rolled condition.
Effect of Heat-to-heat and Melt Practice Variations upon Fatigue Crack Growth in Two Austenitic Steels
Authors: James LA
Published: March 2009

Linear-elastic fracture mechanics techniques were employed to characterize the fatigue-crack growth behavior of five heats of annealed Type 304 (including one heat of Type 304L) and three heats of annealed Type 316 (including one heat of Type 316H) stainless steels at 538°C (1000°F). Specimens were tested under conditions of continuous cycling at 40 cpm, or under tensile hold-time (10.8 min) conditions, producing transgranular or intergranular cracking, respectively. In general, no heat-to-heat variations were noted in the crack growth behavior of either alloy or under the different cycling conditions. Also, the three heats of Type 316 represented three different melt practices, and again there was no apparent effect due to melt practice.
Residual Elements Have Significant Effects on the Elevated-Temperature Properties of Austenitic Stainless Steel Welds
Authors: Edmonds DP , King RT , Goodwin GM
Published: March 2009

The influence of various residual elements on the elevated-temperature properties of austenitic stainless steel welds has been investigated at the Oak Ridge National Laboratory (ORNL). Included in this investigation are the effects of boron, phosphorus, titanium, carbon, sulfur, and silicon. This work is aimed at developing austenitic stainless steel weld materials with enhanced elevated-temperature properties.

The materials investigated include types 308, 316, and 16-8-2 stainless steel weld metals. Processes investigated include shielded metal-arc (SMA), gas tungsten-arc (GTA), and submerged-arc (SA) welding. Early work was done with Types 308 and 316 SMA weld metals, where the greatest enhancement of properties resulted from controlled additions of boron, phosphorus, and titanium to the deposits. Significant improvements in the properties of GTA and SA welds also result from the addition of these residual elements. The optimum residual element compositions were determined to be nominally 0.05Ti-0.04P-0.006B for SMA welds and 0.5Ti-0.04P-0.006B for GTA welds. Submerged-arc welds with 0.2Ti have exhibited improved creep strengths for all three materials.
Design of Asphalt-Rubber Single Surface Treatments with Multilayered Aggregate Structure
Authors: Vallerga BA , Bagley JR
Published: March 2009

A newly developed asphalt-rubber material with unique adhesive and rheological properties has made it possible to form highly elastic single surface treatments with a multilayered aggregate structure. Conventional asphalt distributor trucks are used to apply a heavy spread of the hot asphalt-rubber material on a prepared surface followed by the immediate embedment of aggregate chips into this cast-in-place membrane by conventional chip spreading and rolling equipment and procedures. A sufficient quantity of aggregate chips must be applied both to build up the multilayered aggregate structure and to provide a skid-resistant pavement surface. The composition and properties of the asphalt-rubber material are described together with procedures for constructing the surface treatment. Audit results are presented from an experimental field installation of a multilayered single surface treatment consisting of four test sections, where the rates of application of the asphalt-rubber membrane material ranged from 1.86 to 8.87 hot litre/m2 (0.41 to 1.96 hot gal/yd2) with corresponding aggregate retention rates of 13 to 37 kg/m2 (24 to 68 lb/yd2). Based on these audit results and experience gained from the observed performance of other field installations, a nomograph for designing such multilayered aggregate single-surface treatments has been formulated and is presented. The nomograph can be used to determine the rates of application of asphalt-rubber material and aggregate chips to obtain a desired thickness of surface treatment or, alternatively, to determine the spread rate of aggregate chips and thickness of the surface treatment for a specific rate of asphalt-rubber membrane application.
An Overview of Sulfur-Extended Asphalt Usage
Authors: McBee WC , Sullivan TA , Saylak D
Published: March 2009

Interest in the use of sulfur in highway pavement construction has been stimulated by unpredictable increases in cost and by uncertainty as to the future availability of asphalt cement as a result of the current “energy squeeze”. As a consequence, bid prices for asphalt cement, which have almost tripled over the past three years, are expected to rise even more.

Recent studies and experimental field tests have shown that sulfur can, under certain circumstances, replace as much as 35 volume percent of the asphalt cement used in asphaltic concrete mixes. The unique properties of sulfur, both alone and when blended with asphalt, have also shown potential for use in recycling old bituminous pavements.

This paper attempts to put into perspective the state of the art in design, preparation, placement, and performance evaluation of sulfur-extended asphalt (SEA) pavement mixtures. Various methods of binder preparation are discussed and, where possible, compared on the basis of their physical and engineering properties. The status of three domestic experimental field trials utilizing these methods is reviewed. The potential use of SEA binder to recycle old bituminous pavements is also presented.

Theoretical in-service performance predictions of SEA pavement materials are compared with conventional asphalt cement on the basis of their rutting potential, resistance to cracking, slope variance, and serviceability index. Finally, recommendations for future work are discussed.
Incinerator Residues as Aggregates in Asphaltic Concrete Wearing Mixes
Authors: Ciesielski SK
Published: March 2009

The object of this work was to investigate the use of incinerator residue as an aggregate replacement material in a bituminous concrete wearing course.

Five types of incinerator residue were investigated in the laboratory in the production of asphaltic concrete specimens. The residues ranged from a poorly burned material to a well-burned material. Some experimentation was performed using a 100 percent substitution; however, this did not produce acceptable asphalt concrete. The reported work used a 50 percent substitution rate with conventional Pennsylvania limestone. All mixes were designed to conform to the Pennsylvania ID-2 wearing course gradation and were laboratory tested using the Marshall method of mix design. Satisfactory laboratory mixes were identified for the well-burned incinerator residue. After completion of the laboratory research and design, three experimental pavements were designed, constructed, and monitored.
In Situ AES and ESCA Analysis of Iron Oxides Formed by a Galvanic Cell
Authors: Stout DA , Gavelli G , Lumsden JB , Staehle RW
Published: March 2009

A new approach for the study of metal oxide surfaces has been developed, which makes possible the formation of various oxides under ultrahigh-vacuum conditions. The kinetics of the reactions and the surface oxidation states can be continuously monitored by using various surface analysis techniques. By using a galvanic cell, oxygen can be transported through a solid electrolyte to an iron film, and the oxidation states can be precisely controlled. Wustite (FexO), magnetite (Fe3O4), and hematite (αFe2O3) were formed and investigated, using Auger electron spectroscopy and electron spectroscopy for chemical analysis (ESCA). The peak-to-peak heights for the iron and oxygen Auger transitions were found to correspond to the atomic concentrations, and the binding energies for the different oxide states were measured, using ESCA analysis. The low-energy iron Auger transitions were also monitored, and the appearance of a peak at 47 eV was associated with the formation of metallic iron in the oxygen-iron phase diagram.
Summary
Authors: Davis LE
Published: March 2009

As stated in the introduction, these proceedings were focused on the applied aspects of surface analysis as it is used in practical investigations today. The primary surface analysis techniques described in this volume are Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS or ESCA), secondary ion mass spectrometry (SIMS), and ion scattering spectroscopy (ISS). Articles describing this instrumentation include treatments of instrumental calibration, data handling, and signal processing. The reader also will find that most authors agree that, when more than one of the techniques is used to characterize a single surface, a synergism is possible that cannot be established with a single analytical technique.
Lattice Absorption, Phonon Assignments, and Image Spoiling Properties of Cvd ZnS in the Infrared
Authors: Klein C , diBenedetto B , Donadio R , Kohane T , Pappis J
Published: March 2009

Chemical-vapor-deposited zinc sulfide (CVD ZnS) has been established as a highly promising material for advanced infrared imaging applications and is attracting attention as a potential window material at HF/DF laser wavelengths. The present contribution concerns work that has been carried out in the context of assessing the optical characteristics of CVD-ZnS blanks, particularly with regard to: (a) lattice absorption. Careful examination of transmission traces at wavelengths up to 25µm indicates that multiphonon processes dominate at frequencies below 1000 cm-1; peak-absorption assignments in terms of zone-boundary phonons have been made on the basis of best available inelastic neutron-scattering results for zincblende ZnS. (b) Temperature dependence. Absorption coefficients at temperatures up to 600K have been investigated in light of spectral transmittance and emittance measurements supplemented by calorimetric data at HF, DF, CO, and CO2-laser wavelengths. (c) Image spoiling. Line-spread functions in conjunction with index-inhomogeneity maps demonstrate that wavefront distortions resulting from the presence of a CVD-ZnS window do not inject any detectable degradation in contrast transmittance.
Multithreshold Damage Measurements on As2S3, As2Se3, and NaF at HF and DF Wavelengths
Authors: Donovan TM , Porteus JO , Jernigan JL , Ashley EJ
Published: March 2009

We previously reported on the deposition, absorption, and CO2-laser damage threshold for As2S3, As2Se3, and NaF coatings. It was shown that the damage threshold was much lower for coated than uncoated substrates and that the mechanism for damage was different in the coatings than in the substrates. We speculated that the damage in the coatings was related to the presence of micronsized crystalline defects distributed in the amorphous chalcogenide matrix. In this paper we report the results of damage measurements on these materials at 2.8 and 3.8 µm and identify two operating damage processes: “uniform” damage, which we associate with the amorphous chalcogenide matrix, and “selective” damage, which we associate with the crystalline defects. For single-layer films, we find that N/1 conditioning generally produces an increase in the damage thresholds. The wavelength dependence of multithreshold results in single-layer coatings of As2S3 and NaF suggests that improvement in threshold results from the thermal desorption of contaminating layers of water at 2.7 µm. However, for a dielectrically enhanced reflector containing quarter-wave layers of As2Se3, and NaF, N/1 conditioning promoted crystallite growth which resulted in a definite deterioration of N/1 thresholds.
A Statistical Analysis of Absorptive Laser Damage in Dielectric Thin Films
Authors: Budgor AB , Luria-Budgor KF
Published: March 2009

The Weibull distribution arises as an example of the theory of extreme events. It is commonly used to fit statistical data arising in the failure analysis of electrical components and in DC breakdown of materials.

This distribution is employed to analyze time-to-damage and intensity-to-damage statistics obtained when irradiating thin film coated samples of SiO2, ZrO2, and Al2O3, with tightly focused laser beams. The data used is furnished by Milam. The fit to the data is excellent; we often obtain least squared correlation coefficients greater than 0.9.

It is found almost universally that statistical models of breakdown, such as the lucky electron theory, oversimplify the damage process by neglecting nonlinear interactions and anisotropies induced by impurities. Thus, the fundamental intensity I relation on pulse length tp often deviates from the classical tp-½ dependence resulting from 2-photon absorption without diffusion, or from linear absorption with diffusion, to dependencies as high as tp-0.22 for the former to tp0.44 for the latter. This fact, coupled with the experimental nonobservability of higher than 2-photon absorption seems to imply that the avalanche mechanism is the most likely initiator of the plasma requisite for lattice meltdown.

Statistical confidence bands for material survivability as a function of laser intensity and pulse length can be constructed; this lends high practical utility to the Weibull distribution as an engineering diagnostic tool.
Computer Simulation of Laser Damage Morphology in the Alkali-Halides
Authors: Kelly P , Ritchie D , Bräunlich P , Schmid A
Published: March 2009

A numerical model of the spatio-temporal behaviour of a pico-second laser pulse has been developed which allows the study of the interaction of macroscopic photons with electrons in an alkali-halide lattice. Trajectories of the photons are computed. Gradients in the refractive index change the direction of the photons and this can lead to focusing or defocusing of the pulse. Rotational symmetry is assumed for both the pulse and background. Results obtained to date will be presented.
Frequency Dependence of Breakdown Fields in Single-Crystal NaCl and KCl
Authors: Soileau MJ , Bass M , Van Stryland EW
Published: March 2009

In this paper new observations of the breakdown fields in single-crystal NaCl and KCl are reported. Measurements were made of the wavelength and focal spot radius dependence of breakdown fields in NaCl and KCl at optical frequencies. The measurements at different focal spot radii were used to establish empirical scaling laws for these two materials over the range of focal spot radii studied. Correct application of these scaling laws gives directly comparable fields at all frequencies. The results indicate little dispersion in breakdown fields over the wavelength range of 10.6 to 0.53 µm. The ratio of the NaCl and KCl breakdown fields are found to depend on frequency and this implies that extrinsic phenomena were being probed by these experiments.
Measurement of Organic Pollutants in Water and Wastewater
Authors: Van Hall CE
Published: March 2009

Description

The Symposium on the Measurement of Organic Pollutants in Water and Wastewater was presented in Denver, Colo., 19-20 June 1978. The symposium was sponsored by ASTM Committee D19 on Water. C. E. Van Hall, Dow Chemical Co., presided as symposium chairman; the symposium committee members were: B. F. Afghan, Canada Centre for Inland Waters, J. R. Hall, Hydroscience Associates, Inc., R. J. Joyce, Dohrmann-Envirotech, J. J. Lichtenberg, Environmental Protection Agency, J. P. Mieure, Monsanto Chemical Co., F. T. Weiss, Shell Development Co., and R. E. White, International Joint Commission. Van Hall also served as editor of this publication.
Impediments to Analysis
Authors: Foster JE
Published: March 2009

Description

This volume brings to the forefront some of the problems, which the analytical chemist encounters on a regular basis. These impediments to quality analytical determinations range in nature from objectivity and judgment of the analyst to the technical limitations of procedures and equipment.
Corrosion of Reinforcing Steel In Concrete
Authors: Tonini DE , Gaidis JM
Published: March 2009

Description

This comprehensive volume presents information that can be applied toward the understanding and prevention of corrosion related to coastal or offshore reinforced concrete structures as well as to highway bridges.
Real-Time Radiologic Imaging: Medical and Industrial Applications
Authors: Garrett DA , Bracher DA
Published: March 2009

Description

22 papers cover industrial and medical applications of real-time radiologic imaging methods. Topics include fundamentals, detectors, standards and limits of image formation, special applications, and computer-based systems.
Geothermal Scaling and Corrosion
Authors: Casper LA , Pinchback TR
Published: March 2009

Description

A review containing information on interfacial reactions between fluids and the surfaces of materials in pipes, heat exchangers, and other vessels. Topics include fundamental scientific investigations, field studies of materials in geothermal systems as well as alternative new materials, and chemical aspects of geothermal fluids.
Processing and Testing of Reaction Injection Molding Urethanes
Authors: Ashe WA , Dunleavy RA
Published: March 2009

Description

This book is devoted to the new and expanding technology of reaction injection molding. Specific papers included in this book describe the current and future markets for RIM products. Technology areas examined include: research and development in RIM equipment design, RIM processing parameters, and RIM product characterization and evaluation, to provide elucidation of the relationships between chemical structure and engineering and thermal product properties.
Florfenicol Residues in Three Species of Fish after 10-Day Oral Dosing in Feed
Authors: Kosoff R. E. , Chen C-Y. , Wooster G. A. , Getchell R. G. , Bowser P. R. , Clifford A. , Craig J. L. , Lim P. , Wetzlich S. E. , Craigmill A. L. , Tell L. A.
Published: March 2009

Nile tilapia Oreochromis niloticus, walleye Sander vitreus, and hybrid striped bass (female white bass Morone chrysops × male striped bass M. saxatilis) were medicated with florfenicol (AQUAFLOR type A medicated article; Schering-Plough Animal Health, Summit, New Jersey) via a medicated ration of 10 mg florfenicol·kg fish body weight−1·d−1 for 10 d to compare the elimination kinetics of the test article. This study was part of a larger effort in support of a species grouping concept that could contribute to the regulatory approval process for therapeutic compounds for cultured fishes. The trials in this study were conducted at the ideal water temperature for each species and at the temperature 5°C lower than the ideal. The test temperatures were 30°C and 25°C for Nile tilapia, 25°C and 20°C for both walleyes and hybrid striped bass. In all cases, the elimination kinetics of florfenicol were more rapid at higher temperatures. The time to reach the tolerance of 1 μg/g in muscle–skin, as set by the U.S. Food and Drug Administration for channel catfish Ictalurus punctatus and salmonids, ranged from 6.1 to 4.1 d for Nile tilapia, from 12.6 to 9.7 d for walleyes, and from 2.6 to 0.7 d for hybrid striped bass at temperatures between 20°C and 30°C.
Florfenicol Residues in Nile Tilapia after 10-d Oral Dosing in Feed: Effect of Fish Size
Authors: Bowser P. R. , Kosoff R. E. , Chen C-Y. , Wooster G. A. , Getchell R. G. , Craig J. L. , Lim P. , Wetzlich S. E. , Craigmill A. L. , Tell L. A.
Published: March 2009

Nile tilapia Oreochromis niloticus were medicated with florfenicol (AQUAFLOR type A medicated article; Schering-Plough Animal Health, Summit, New Jersey) via a medicated ration at 15 mg florfenicol·kg fish body weight−1·d−1 for 10 d to compare the elimination kinetics of the test article in different size fish held at 25°C. The groups of fish used in the study had mean weights of approximately 100, 250, and 500 g. In each trial, the fish were provided the medicated ration and 15 fish were processed at each of seven time points postfeeding for determination of the florfenicol concentration in serum and the florfenicol residue in the edible portion (composite muscle and skin). There was a trend toward shorter half-lives of elimination in the smaller fish. The elimination times in muscle–skin (times to reach the established tolerance concentration for channel catfish Ictalurus punctatus and salmonids of 1.0 μg florfenicol residue/g) and half-lives were 9.2 and 1.2 d (100 g), 8.6 and 1.7 d (250 g), and 12.7 and 2.2 d (500 g), respectively.
Summer Movements of Juvenile Coho Salmon under Variable Stream Flow Conditions
Authors: Lonzarich David George , Franckowiak Ryan Patrick , Allen Matthew David
Published: March 2009

We describe the distribution of juvenile (age‐0) coho salmon Oncorhynchus kisutch and the effects of summer flooding on their movements in a small Lake Superior tributary. We documented large fluctuations in fish abundance over a 60‐d survey period by conducting repeated snorkeling surveys within 16 reaches and 82 individual habitat units in a 2‐km segment of the Onion River, Wisconsin. Fish densities in reaches were more stable than those within individual habitat units. Moreover, temporal trends in fish abundance were correlated strongly with the physical features of reaches but not with those of individual habitat units. In focusing on fine‐scale changes in fish distribution, we uncovered three general patterns of movement within this stream. The first was associated with flood events, which caused the downstream displacement of large numbers of fish (up to 80% loss from individual pools). The second was the upstream recolonization of fish into depleted pools during the intervening periods of low flow, and the third was small‐scale movement within reaches. Three separate floods did not cause a decline in average pool densities over the study; however, there was a strong shift away from glide habitats and a concentration of fish in the middle reaches of the stream by the study's conclusion. Movement of the type and magnitude described here has clear implications for the association of fish with physical habitat conditions. We also speculate that such movement may have effects on social hierarchies and the relative fitness of individual coho salmon.
Water Velocity, Turbulence, and Migration Rate of Subyearling Fall Chinook Salmon in the Free‐Flowing and Impounded Snake River
Authors: Tiffan Kenneth F. , Kock Tobias J. , Haskell Craig A. , Connor William P. , Steinhorst R. Kirk
Published: March 2009

We studied the migratory behavior of subyearling fall Chinook salmon Oncorhynchus tshawytscha in free‐flowing and impounded reaches of the Snake River to evaluate the hypothesis that velocity and turbulence are the primary causal mechanisms of downstream migration. The hypothesis states that impoundment reduces velocity and turbulence and alters the migratory behavior of juvenile Chinook salmon as a result of their reduced perception of these cues. At a constant flow (m3/s), both velocity (km/d) and turbulence (the SD of velocity) decreased from riverine to impounded habitat as cross‐sectional areas increased. We found evidence for the hypothesis that subyearling Chinook salmon perceive velocity and turbulence cues and respond to these cues by varying their behavior. The percentage of the subyearlings that moved faster than the average current speed decreased as fish made the transition from riverine reaches with high velocities and turbulence to upper reservoir reaches with low velocities and turbulence but increased to riverine levels again as the fish moved further down in the reservoir, where velocity and turbulence remained low. The migration rate (km/d) decreased in accordance with longitudinal reductions in velocity and turbulence, as predicted by the hypothesis. The variation in migration rate was better explained by a repeated‐measures regression model containing velocity (Akaike's information criterion = 1,769.0) than a model containing flow (2,232.6). We conclude that subyearling fall Chinook salmon respond to changes in water velocity and turbulence, which work together to affect the migration rate.
Exploring the Persistence of Stream‐Dwelling Trout Populations under Alternative Real‐World Turbidity Regimes with an Individual‐Based Model
Authors: Harvey Bret C. , Railsback Steven F.
Published: March 2009

We explored the effects of elevated turbidity on stream‐resident populations of coastal cutthroat trout Oncorhynchus clarkii clarkii using a spatially explicit individual‐based model. Turbidity regimes were contrasted by means of 15‐year simulations in a third‐order stream in northwestern California. The alternative regimes were based on multiple‐year, continuous monitoring in two streams. Turbidity affected model fish by reducing both their risk of predation and their reactive distance to drifting prey. It did not affect their ability to locate nondrifting food, such as invertebrates on the stream bottom. Under a calibration scenario that assumed trout predominantly consume drifting prey, the less‐turbid real‐world regime produced relatively stable abundance across years (similar to field observations) whereas the more‐turbid regime (under otherwise identical physical conditions) resulted in extinction within the 15‐year simulation period. Additional simulations revealed sensitivity to the relative amounts of prey available via drift versus search feeding and showed that seasonal variation in food availability or strong positive relationships between streamflow and food concentration would not prevent extinction in the high‐turbidity regime under a drift‐feeding‐based food calibration. Extinction of predominantly drift‐feeding trout populations in our simulations contrasts with field observations of salmonid populations that have persisted in moderately turbid regimes. The results highlight the need for better understanding of patterns in the availability of food under turbid conditions and the capability of stream salmonids to use nonvisual cues in feeding.
Implications of Beaver Castor canadensis and Trout Introductions on Native Fish in the Cape Horn Biosphere Reserve, Chile
Authors: Moorman Michelle C. , Eggleston David B. , Anderson Christopher B. , Mansilla Andres , Szejner Paul
Published: March 2009

Invasive species threaten global biodiversity, but multiple invasions make predicting the impacts difficult because of potential synergistic effects. We examined the impact of introduced beaver Castor canadensis, brook trout Salvelinus fontinalis, and rainbow trout Oncorhynchus mykiss on native stream fishes in the Cape Horn Biosphere Reserve, Chile. The combined effects of introduced species on the structure of the native freshwater fish community were quantified by electrofishing 28 stream reaches within four riparian habitat types (forest, grassland, shrubland, and beaver‐affected habitat) in 23 watersheds and by measuring related habitat variables (water velocity, substrate type, depth, and the percentage of pools). Three native stream fish species (puye Galaxias maculatus [also known as inanga], Aplochiton taeniatus, and A. zebra) were found along with brook trout and rainbow trout, but puye was the only native species that was common and widespread. The reaches affected by beaver impoundments had significantly higher puye densities than all other reaches in this study. These results are comparable to those reported for other streams in southern Chile. The presence of trout reduced the abundance of puye, but only in beaver‐affected areas; all three natural riparian habitat types had uniformly low puye abundance and were unaffected by the presence or absence of trout. The data suggest that one invasive species, the beaver, enhanced puye habitat and thereby increased the abundance of that species, which, in turn, helped moderate the negative impacts of invasive trout.
Age Validation of Freshwater Drum using Bomb Radiocarbon
Authors: Davis‐Foust Shannon L. , Bruch Ronald M. , Campana Steven E. , Olynyk Robert P. , Janssen John
Published: March 2009

The ages of freshwater drumAplodinotus grunnienshave typically been estimated by counting the growth increments on their scales or otoliths, but the accuracy of these estimates has not been validated. We used accelerator mass spectrometry (AMS) bomb radiocarbon dating to validate age estimates from sagittal otoliths of freshwater drum from the Lake Winnebago system, Wisconsin. The freshwater drum Δ14C chronology from the AMS assay closely reflects the timing and shape of other bomb radiocarbon chronologies, thus validating the accuracy of otolith growth increments to at least age 52 ± 2 years. The progression of a strong 1983 year‐class, which was detected every year sampled over the course of the study (1986, 2003‐2007), and indices of year‐class abundance calculated from trawling assessments on Lake Winnebago (1986‐2007) corroborated otolith ages. Age estimate comparisons between scales, anal spines, dorsal spines, and otoliths showed scales and spines to be completely unreliable as aging structures after age 2. Freshwater drum live to very old ages relative to most other Great Lakes fishes; our oldest specimen based on an otolith age estimate was 58 years old.
Lake Sturgeon Age Validation using Bomb Radiocarbon and Known‐Age Fish
Authors: Bruch Ronald M. , Campana Steven E. , Davis‐Foust Shannon L. , Hansen Michael J. , Janssen John
Published: March 2009

Pectoral fin spines have been the accepted structure for estimating the age of various sturgeon species for nearly 100 years, though other structures have also been used (otoliths, pectoral girdle, scutes, and caudal fulcra). Accuracy of age estimates using any of these structures has not been validated, so we report the first use of bomb radiocarbon (14C) assays to assess the validity of ages estimated using growth increments on pectoral fin spine and otolith frontal cross sections from lake sturgeon Acipenser fulvescens; we also assessed age estimates from pectoral fin spines of known‐age lake sturgeon. Growth increments on pectoral fin spine cross sections underestimated true age of fish older than 14 years and error increased with age, whereas otoliths accurately estimated true age up to at least 52 years. Increment formation on pectoral fin spine and otolith cross sections from juvenile lake sturgeon (ages 2‐11) was similar, although pectoral spines were clearer and easier to interpret. A power function (true age = [estimated age]1.054796, where estimated age was determined from pectoral spines; r2 = 0.98) provides a means for correcting existing age estimates obtained from lake sturgeon pectoral fin spines.
Lateral buckling of plate girders with flexible restraints
Authors: Hendy C. R. , Jones R. P.
Published: March 2009

Since publication of BS 5400: part 3 in 2000, the design check of paired plate girders during erection has become more onerous in the UK. This change has been brought about by the addition of two main features in BS 5400: part 3—a change to the mode of buckling considered in deriving girder slenderness and the addition of more conservative buckling curves when the effective length for buckling differs from the half-wavelength of buckling. BS EN 1993-1-1 requires no such reduction in resistance. The work presented in this paper was prompted by a proposal to modify the rules of BS EN 1993-2 for bridges in the UK's national annex to be more like those in BS 5400: part 3. The authors believed this to be unnecessary. This paper investigates buckling cases where the effective length for buckling is shorter than the half-wavelength of buckling and demonstrates that the series of correction curves used in BS 5400: part 3 are unnecessary and that the BS EN 1993-1-1 method is satisfactory and slightly conservative. The paper also outlines the design process to BS EN 1993 using both elastic critical buckling analysis and non-linear analysis. The case studies considered are a simple pin-ended strut with intermediate restraints, a pair of braced girders prior to hardening of the deck slab and a half-through deck with discrete U-frame restraints. For the latter two cases, the results predicted by BS 5400: part 3 and BS EN 1993-1-1 are compared with the results of non-linear finite-element analyses.
Application of a stable isotope technique to determine the simultaneous uptake of cadmium, copper, nickel, lead, and zinc by the water fleaDaphnia Magnafrom water and the green algaePseudokirchneriella Subcapitata
Authors: Komjarova Irina , Blust Ronny
Published: March 2009

Accumulation and toxicological effects of water and dietary metals in aquatic organisms can potentially be very different. Therefore, it is important to know the relative contribution of these different sources to metal exposure, availability, and accumulation. In the present study, a stable isotope technique was applied to investigate the uptake of Cd, Cu, Ni, Pb, and Zn by the green alga Pseudokirchneriella subcapitata and the water flea Daphnia magna during simultaneous exposure to the five metals at environmentally realistic concentrations from separate water and dietary routes. Green algae take up Cu faster compared to Cd, Ni, Pb, and Zn, and the distribution of metals between the external and internal compartments is dependent on metal and population growth stage. The metal accumulation reached a steady state within 24 to 48 h for all metals. Metal uptake rate constants from water were highest for Cu and lowest for Ni. Metal assimilation efficiencies from the food source varied with metal, ranging from approximately 80% in the case of Cd to near 0% in the case of Ni. Because the data for the different metals were obtained on the same multimetal-exposed organisms, the results are directly comparable among the metals. For all five metals studied, water appeared to be the most important route of uptake by D. magna.
Effects of dietary N-acetylcysteine on the oxidative stress induced in tilapia (Oreochromis Niloticus) exposed to a microcystin-producing cyanobacterial water bloom
Authors: Puerto María , Prieto Ana I. , Pichardo Silvia , Moreno Isabel , Jos Ángeles , Moyano Rosario , Cameán Ana M.
Published: March 2009

Fish can be exposed to toxic cyanobacterial cells in natural waters and fish farms and suffer from oxidative damage. The present study investigates the effects of N-acetylcysteine (NAC), a glutathione (GSH) precursor, on the oxidative stress induced by Microcystis cyanobacterial cells containing microcystins (MCs) in tilapia fish (Oreochromis niloticus). Variation in lipid peroxidation (LPO) levels, carbonyl group content, reduced glutathione to oxidized glutathione ratio (GSH: GSSG), and catalase (Enzyme Commission [EC] 1.11.1.6), superoxide dismutase (SOD; EC 1.15.1.1), glutathione reductase (GR; EC 1.8.1.7), glutathione peroxidase (GPx; EC 1.11.1.9), and glutathione S-transferase (EC 2.5.1.18) activities in liver and kidney of tilapia exposed to a single oral dose of 120 μg MC-LR (with leucine [L] and arginine [R])/fish and killed in 24 h were investigated in the absence and presence of 20.0, 44.0, and 96.8 mg NAC/fish/d. Results showed a protective role of NAC, depending on the dose and the biomarker considered. The increase in LPO (1.9-and 1.4-fold in liver and kidney, respectively) and the decreased protein content and GSH:GSSG in the liver induced by MCs were recovered mainly by the lower doses of NAC employed. Antioxidant enzyme activities increased (range, 1.4-to 1.7-fold) by MCs also were ameliorated by NAC, although the highest level used induced significant alteration of some enzymatic activities, such as SOD, GPx, and GR. Thus, NAC can be considered to be a useful chemoprotectant that reduces hepatic and renal oxidative stress in the prophylaxis and treatment of MC-related intoxications in fish when careful attention is given to its application dose because of its own pro-oxidant activity, as shown in the present study at 96.8 mg NAC/ fish/d.
Quantum-SAR Extension of the Spectral-SAR Algorithm. Application to Polyphenolic Anticancer Bioactivity
Authors: Putz Mihai V. , Putz Ana-Maria , Lazea Marius , Ienciu Luciana , Chiriac Adrian
Published: March 2009

Aiming to assess the role of individual molecular structures in the molecular mechanism of ligand-receptor interaction correlation analysis, the recent Spectral-SAR approach is employed to introduce the Quantum-SAR (QuaSAR) “wave” and “conversion factor” in terms of difference between inter-endpoint inter-molecular activities for a given set of compounds; this may account for inter-conversion (metabolization) of molecular (concentration) effects while indicating the structural (quantum) based influential/detrimental role on bio-/eco- effect in a causal manner rather than by simple inspection of measured values; the introduced QuaSAR method is then illustrated for a study of the activity of a series of flavonoids on breast cancer resistance protein.
Anaerobic Biodegradation of Detergent Surfactants
Authors: Merrettig-Bruns Ute , Jelen Erich
Published: March 2009

Detergent surfactantscan be found in wastewater in relevant concentrations. Most of them are known as ready degradable under aerobic conditions, as required by European legislation. Far fewer surfactants have been tested so far for biodegradability under anaerobic conditions. The natural environment is predominantly aerobic, but there are some environmental compartments such as river sediments, sub-surface soil layer and anaerobic sludge digesters of wastewater treatment plants which have strictly anaerobic conditions. This review gives an overview on anaerobic biodegradation processes, the methods for testing anaerobic biodegradability, and the anaerobic biodegradability of different detergent surfactant types (anionic, nonionic, cationic, amphoteric surfactants).