bluuebunny/crossref_metadata_2025_split huggingface dataset:
Taint Threshold of Diphenyl Oxide in Rainbow Trout
Authors: Branson DR , Blau GE , Alexander HC , Peters TL 
Published: March 2009

Rainbow trout were exposed continuously for seven days to sublethal concentrations of diphenyl oxide (DPO) in water. The trout flesh was then analyzed for taste and DPO concentrations. The following conclusions were based on the experimental results:
1. Trout flesh containing 7.5 ± 1.2 μg/g DPO was identified by a panel as characterizing the breakpoint between tainted and untainted taste. Trout exposed continuously to 16 μg/litre of DPO in the water for one week show flesh concentrations of DPO that correspond to this fish-taint threshold.
2. The DPO concentrations in trout flesh increased 1.75 times after baking. This phenomenon could be due to water loss and to possible transfer of DPO from the skin to the flesh during baking. Cooked trout flesh containing 13 ± 2 μg/g DPO were at the fish-taint threshold.
3. A statistically significant correlation was obtained between fish-taint scores and the DPO concentration in flesh, which permits the prediction of fish taint to be made from a given DPO residue in fish.
4. Statistical analysis of the taste data indicated that neither taste fatigue nor taster experience was a factor in this study.
5. This study illustrates that taint in fish can be one of the more sensitive water quality criteria for some chemicals.
Value of Chemical Fractionation for Identifying the Toxic Components of Complex Aqueous Effluents
Authors: Parkhurst BR , Gehrs CW , Rubin IB 
Published: March 2009

Chemical fractionation can be used to separate complex aqueous effluents into several less complex fractions, and this technique has been combined with mutagenesis testing to provide an effective means of screening the potential health hazards of products and of aqueous effluents. The purpose of this study was to evaluate the applicability of combining chemical fractionation with acute toxicity testing as a method of identifying and quantitatively assessing those components of a synthetic fuel process effluent that are toxic to aquatic biota.
A representative synthetic fuel effluent was fractionated into three organic fractions (acid, base, and neutral) and an inorganic fraction. The original effluent, the fractions, and a reconstituted effluent were tested for acute toxicity to Daphnia magna.
The results demonstrated that (1) the neutral fraction was the most toxic; (2) the acid and neutral fractions contributed the most toxicity, 51.3 and 41.9 percent, respectively, to the toxicity of the whole effluent; (3) the toxicities of the four fractions were additive; and (4) the fractionation process did not significantly alter the toxicity of the effluent. Possible applications of this approach, as well as its limitations, are discussed.
Bioconcentration and Metabolism of Linear Alkylbenzene Sulfonate by Daphnids and Fathead Minnows
Authors: Comotto RM , Kimerle RA , Swisher RD 
Published: March 2009

The bioconcentration potential of the anionic surfactant linear alkylbenzene sulfonate (LAS) was studied using daphnids (Daphnia magna) and fathead minnows (Pimephales promelas) in studies extending up to 50 days. Uptake in the test organisms, as measured by 14C activity, was a function of chain length and exposure concentration. In whole organisms, the dry weight bioconcentration factors (BCF) were 500 to 4000 for daphnids and 200 to 2000 for fathead minnows. In fish tissues, the greatest 14C activity occurred in the gall bladder, the BCFs ranging from 20 000 to 70 000, while the least occurred in the muscle, the BCFs remaining in the range of 100 to 400. In depuration studies, greater than 85 percent of the 14C content was cleared from all tissues within three to four days, with nearly 100 percent clearance within ten days.
The results of desulfonation/gas chromatography analyses of tissues suggested that the fathead minnows metabolised LAS, and the daphnids did not. Substantial portions of the 14C content in the tissues of fathead minnows were not present as LAS, but presumably were present as metabolites (30 to 50 percent in muscle tissue, and 97 percent or more in the case of the gall bladder). A comparison of the uptake of 14C from tagged LAS with that from tagged taurocholic acid (TCA), a naturally occurring bile surfactant, gave somewhat contrasting uptake patterns in fathead minnows. The 14C-LAS activity reached a steady state in tissues within three days, while the 14C-TCA activity continued to accumulate in tissues throughout the exposure period.
It can be concluded from these LAS and TCA bioconcentration studies that surfactant materials may, in general, show similar patterns of uptake, site of deposition, metabolism, and depuration. From the present studies and from previously reported toxicity and microbial biodegradation studies, it can be further concluded that under environmental conditions there is little likelihood that LAS bioconcentration creates a hazard to aquatic ecosystems.
Exposure Assessment: A Key Issue in Aquatic Toxicology
Authors: Sanders WM 
Published: March 2009

Environmental exposure assessment, an intermediate step in risk analysis, ties projected volumes of toxic materials entering the environment to specific environmental effects. Thus, prediction of the environmental fate and distribution of a toxic compound is an integral part of any hierarchical scheme of risk analysis.
Environmental exposure assessment is a new and emerging science, and, although some processes have not been adequately characterized, tests for the most significant ones (volatilization, hydrolysis, oxidation, etc.) are available. Both screening tests and detailed protocols are presently available for determining the process kinetics for selected chemicals exposed to differing environmental conditions. Preliminary exposure assessments can be made from the screening data if the following rate processes are estimated: microbial degradation, chemical transformation, photolysis, hydrolysis, ionization, and partitioning. Because these processes can act either synergistically or competitively, depending upon the chemical structure of the material and the conditions of the environment, great care must be taken to conduct the tests in sequential order.
The greatest unrealized potential for exposure assessment lies in the use of mathematical modeling techniques. When environmental exposure models are coupled with environmental effects models, powerful tools for risk assessment emerge. Such sophisticated models need to be refined and verified, however, before risk analysis becomes accurate and cost-effective.
Effects of Calcium and Sediment Concentrations on the Release of Metals and Nutrients from Dredge Spoil Dispersions
Authors: Snitz FL , Weber WJ , Barney JL , Posner JC 
Published: March 2009

Sediment from the lower Cuyahoga River (5.8 river km from the mouth at Lake Erie) was dispersed in reactors containing simulated lake water constituted to have pH, dissolved oxygen (DO), alkalinity, and hardness values typical of Great Lakes Waters. The parameters of pH and DO were maintained constant during the course of the experiments, while calcium and sediment dispersion concentrations were systematically varied. The calcium ranged from 5 to 120 mg/litre and the sediment from 0.5 to 50 g(dry)/litre.
The materials investigated for release from the sediment dispersions included magnesium, cadmium, copper, lead, zinc, iron, manganese, chromium, arsenic, total dissolved phosphate as PO4, and total Kjeldahl nitrogen. In general, the extent of release was inversely related to the calcium and sediment concentrations. Significantly, the unit release of metals and nutrients in oxygenated waters increased two to five-fold with each order-of-magnitude decrease in sediment dispersion concentration.
The methods of the research bear upon the development of procedures for evaluating the potential impact of dredging operations on water quality. The results of this investigation show that the amounts of dredge spoil constituents released into solution can be comparable in magnitude to those of dissolved mineral species in rivers and outfalls.
Identification of Organic Components in Aqueous Effluents from Energy-Related Processes
Authors: Pellizzari ED , Castillo NP , Willis S , Smith D , Bursey JT 
Published: March 2009

The qualitative and quantitative comparison in seven aqueous samples from four different energy-related operations were determined. Striking differences were observed in both the types and quantities of individual organics in samples from coal and oil shale processes. High-resolution gas chromatography coupled with mass spectrometry and Fourier transform infrared spectroscopy was required to provide sufficient separation and molecular characteristics for identification of each organic substituent. These instrumental processes must be computerized to allow for fast data reduction.
A greater amount and diversity of nitrogen-containing compounds were found in samples from in situ oil shale processing. Few qualitative differences were apparent among samples from in situ and low-Btu coal gasification.
Effect of Flash Point on the Design and Operation of SST Aircraft
Authors: Boucher HT 
Published: March 2009

The effect of flash point reduction and, therefore, the increase of vapor pressure on the design and operation of a supersonic transport (SST) is examined in detail. Considering an SST design, which has been optimized on the basis of a kerosine flash point of 38°C (100°F), the effect on design criteria of lowering flash point by 5.5°C (10°F) is equivalent to a cost penalty, to each SST aircraft in the order of $45 000 per year. A further 5.5°C (10°F) lowering would increase the penalty to some $125 000 per year. The penalty is not incurred in full where existing designs have included a margin to allow for lower flash points fuels.
The main effect of lower flash point fuels upon the safety of supersonic aircraft lies in the greater flame speed across pools of fuel which might be spilled in crash landings.
On-Line Safety Monitoring of a Large High Pressure High Temperature Autoclave
Authors: Tatro CA , Brown AE , Freeman TH , Yanes G 
Published: March 2009

Four years of experience with on-line monitoring of a large autoclave used primarily for forming bonds and material densification is reported. The purpose of this work is to confirm that no flaws are growing in the autoclave during operation. Failure of this device during operation could endanger personnel and would damage property. Its loss would seriously curtail several ongoing research efforts.
The vessel is monitored with a commercial minicomputerized flaw location system. Four 4-sensor arrays are attached to the exterior of the device to receive acoustic emission signals. Computed locations are stored on cassette tape and selected portions can be displayed on a cathode ray screen. It is shown that although the minicomputer is implemented with two dimensional location software, the information can be reprocessed in a central computer to produce locations in three dimensions.
Long-term storage of data, data display, noise analysis, calibration, and computerized location error analysis is discussed.
No degradation by flaw growth has been detected in this device to date. This is the expected result, since it has an estimated 30-year life.
A High Signal-to-Noise Oscillator for Contactless Measurement of Photoinduced Carrier Lifetimes
Authors: Curtis HW , Verkuil RL 
Published: March 2009

A wide-band apparatus for contactless measurement of small changes in photoinduced carrier population is described. Since for some phenomena the signals of interest have very low amplitude, and since the generator supplying energy for the measurement is an oscillator loosely coupled electromagnetically to the semiconductor, very-low-noise circuitry is required. Further, sensitivity to minute conductivity changes is enhanced when the oscillation amplitude is made directly proportional to the figure of merit, Q, of the coupled oscillator resonant parallel inductance-capacitance (LC) tank. The circuit to approximate the desired dependence, amplitude = kQ, contains only two field-effect transistors and is basically an oscillator supplied by a constant current rather than by a constant voltage source. Its operation is analyzed via modeling that specifies the output signal as a function of device and circuit parameters; excellent correspondence with empirical data is shown.
The oscillator also operates as an infinite impedance detector of its own amplitude; this amplitude is shown to be linearly dependent on carrier concentration over significant ranges. Thus, the oscillator steady-state and transient responses may be directly related to wafer conductivity, induced carrier amplitude, and lifetime. The described apparatus is sensitive to carrier concentration changes of less than 1011 electrons or holes per cubic centimetre of silicon and will provide measurement of lifetimes from a microsecond to several seconds.
Multiparticle Erosion of Pyrex Glass
Authors: Sargent GA , Mehrotra PK , Conrad H 
Published: March 2009

Multiparticle erosion tests were performed on Corning 7740 Pyrex glass using alumina powder of two grit sizes. Erosion was measured as a dimensionless parameter in terms of the loss in weight of the target per unit weight of particles impinged. The erosion characteristics of the Pyrex glass were investigated over a range of particle velocities, angles of impingement, and times of erosion.
It was found that maximum erosion occurred at a normal angle of impact for the 240-grit powder (mean particle size ≃ 30 μm); however, with the 400-grit powder (mean particle size ≃ 10 μm), the maximum was found to occur at a slightly lower angle of about 80 deg. At all angles of impingement it was found that amount of erosion decreased as the erosion time increased.
Erosion (E) was found to be dependent on the average particle velocity (V) by a power relationship of the form EαVn where n is a material constant. The values of the velocity exponent, n, in the present experiments were found to be between 2.2 and 2.7 and were independent of time of erosion.
The time (t) dependence of erosion was also found to obey a power law relationship of the form Eαtc where c is a material constant. The time exponent c was found to be -0.1 under all conditions of velocity, particle size, and angle of impingement. The decrease in erosion with increase in time has been interpreted in terms of a change in the surface roughness. Scanning electron microscopy (SEM) has been used to establish that the effective average angle of impingement decreased as time of erosion increased until a constant surface roughness was achieved, at which time it was found that the average angle of impingement was about 55 deg instead of 90 deg.
The experimental data obtained in the present work are discussed in terms of existing theories for the erosion of brittle materials.
Influence of Materials Construction Variables on the Rain Erosion Performance of Carbon-Carbon Composites
Authors: Schmitt GF 
Published: March 2009

The influence of materials construction variables and environmental parameter effects on the rain erosion behavior of carbon-carbon reentry vehicle nosetip thermal protection materials has been investigated at velocities of 1220 to 1675 m/s by firing rocket sleds equipped with special specimen holders through the artificial rain-field at Holloman Air Force Base.
A high percentage of axial reinforcement (fibers end-on to the surface) is desirable in carbon-carbon composites for improved erosion resistance. One-dimensional reinforcement of this type would provide maximum erosion resistance, but the need for structural properties in reentry vehicle applications requires a combination of this high axial loading with fine-weave orthogonal 3-dimensionally reinforced construction for enhanced erosion-resistance and balanced performance. The small unit cell size is essential for good resistance. Increased in-plane isotropy in these composites by rotating the X-Y plies reduced the macroroughness development which is typical of the carbon-carbon composites in the multiple rain environment.
Improvements in weaving, impregnation, pyrolysis, and graphitization are reflected in a reduction in the mass loss ratio of composites which have similar Z bundle area fractions, but were made at different chronological times.
It was determined that Thornel 50 fiber composites gave better performance than Thornel 75, C-1000, C-3000, and other fibers. The introduction of intermediate chemical vapor deposition (CVD) of carbon coupled with low- or high-pressure pitch processing provided matrices for composites with improved erosion resistance compared with pyrolyzed resin or pitch-only processes.
Empirical relationships were determined to govern the erosion rate as a function of velocity and impingement angle.
Elastic-Plastic Fracture Toughness Based on the COD and J-Contour Integral Concepts
Authors: Dawes MG 
Published: March 2009

The paper reviews the definition, fracture characterizing roles, and measurement of critical COD and J-values. It is proposed that COD should be defined as the opening displacement at the original crack tip position. This definition avoids much of the ambiguity of previous definitions based on the crack tip profile and the elastic-plastic interface. Attention is drawn to a fundamental problem which limits the general application of the J-contour integral concept to elastic-plastic descriptions of the crack tip environment when cracks occur in overmatching yield strength weld regions. A comparison of recent three-point single-edge notch bend (SENB) testing techniques, based on the standard instrumentation used in KIc tests, shows there is a close mathematical link between the estimated values of COD and J.
Experimental data, obtained over a wide range of temperatures, are used to demonstrate how the critical values of COD and J for unstable fracture are affected by variations in specimen geometry. Also, it is shown that measurements of JIc may lead to overestimates of KIc in materials having yield strengths less than approximately 700 N/mm2.
Elastic-Plastic Fracture Mechanics Analyses of Notches
Authors: Hammouda MM , Miller KJ 
Published: March 2009

Fatigue failures invariably start at a surface notch. Crack initiation is due to plasticity while crack propagation can continue in an elastically stressed material due to the crack generating its own crack tip plasticity.
From elastic-plastic analyses, it is possible to predict the effect of notch plasticity on the behavior of short propagating cracks. Elastic-plastic finite-element analysis solutions to cracks in notch fields indicate that a crack will initially propagate at a decreasing rate until the crack can generate a crack tip plasticity that is greater than the elastic threshold stress intensity condition.
Simulation and Monitoring of Loads in Crane Beams
Authors: Weiss MP 
Published: March 2009

The fracture mechanics approach to design of steel structures uses the stress range distribution function as the main parameter that governs crack propagation and possible failures. It is an accepted fact that all welded structures contain existing small cracks that propagate as a function of varying stress ranges and stress intensity factors. The main problem is to predict correctly the nature of the varying stresses and to analyze them for fatigue evaluation.
Crane structures are exposed constantly to different static and dynamic loads and their stress distribution is quite complex. In this study, stress distributions in an overhead travelling bridge crane beam are evaluated by computer simulation and by monitoring real structures with a specially developed test setup.
The simulation starts with generating beta distributed random loads, and random loading and unloading places in the service area. These points are generated by means of a new general distribution model. Stress peaks and ranges are calculated and counted per each loading cycle.
The test setup uses regular load cells, with specially designed fixtures and A/D converters, to record data on perforated tapes.
The simulations were used to plot general distributions of stress peaks and ranges. The test results are special cases of the general distributions.
The results of this study are being used currently to evaluate fatigue lives and safe stresses in crane structures, and to update design codes.
Some Observations on the Role of Cellular Enzymes in the In-Vivo Degradation of Polymers
Authors: Williams DF 
Published: March 2009

The in vivo and in vitro degradation of some suture materials, especially polyglycolic acid sutures, has been studied in an attempt to determine whether cellular enzymes have any influence on the degradation of polymers. The test protocols included a novel method for varying the type of tissue response to a material so that the in-vivo behavior of the material under different conditions could be followed.
It has been found that the hydrolysis of polyglycolic acid takes place by essentially the same mechanism in vivo and in vitro—that is, by hydrolysis in an aqueous environment—but that the initiation of this process is greatly enhanced by the in-vivo environment. The cells of an acute response to implant material appear to favor hydrolysis slightly more than do cells of a chronic response. A similar but more significant difference in tissue environmental effect is noted with the use of polyamide sutures, but the situation is reversed when silk sutures are used; then the chronic inflammatory cells have a greater effect on the suture materials than do the acute inflammatory cells.
L10 versus Leq—A User's Perspective
Authors: Cohn LF , McColl W 
Published: March 2009

The Federal Highway Administration (FHWA) regulation tor highway traffic noise analysis, FHPM 7-7-3, allows for the use of either L10 (sound level exceeded 10 percent of the time) or Leq (energy equivalent sound level). Therefore, state highway agencies have the responsibility to empirically determine the preferable descriptor (L10 or Leq) for typical highway projects.
As such, the New York State Department of Transportation (NYSDOT) has performed several such studies in recent years. Among those are an analysis of two major prediction methodologies (National Cooperative Highway Research Program (NCHRP) Reports 117 and 174), and a long term measurement study of the Youngmann Expressway Noise Abatement Project in Buffalo, N.Y.
Results of these two studies indicate that both L10 and Leq are satisfactory descriptors for proposed highway projects. However, for vehicular flow rates of somewhere less than 400 automobiles per hour, L10 becomes suspect because the assumption of equal vehicular spacing becomes non-valid. For long-term studies, Leq is very sensitive to equipment malfunction, but is superior to L10 in its ability to consider short duration, random occurrences.