bluuebunny/crossref_metadata_2025 huggingface dataset:
Allometric Growth Response of Exercised Rainbow Trout to Cyanide Poisoning
Authors: McCracken IR , Leduc G
Published: March 2009

The toxicity of cyanide to juvenile rainbow trout held in swimming chambers during 20-day growth experiments at 10°C was found to be size related, the larger trout being more adversely affected than the smaller ones.

The results of four experiments on control and cyanide-exposed trout forced to swim against a constant current speed of 12.1 cm/s while being fed restricted rations revealed that cyanide at 0.01 mg/litre hydrogen cyanide (HCN) increased the food maintenance requirement of the large fish, which were growing less rapidly than their respective controls. The smaller fish, however, grew faster than their controls when exposed to cyanide because of a faster accumulation of lipids.

The metabolic rate of fish is related to size, and this relation is described by the allometric formula Y = aXb, where Y is the metabolic rate, X the body size, a the Y-intercept, and b the weight exponent and slope. This formula was applied to the present results, and a log-log plot of dry weight gains against initial wet weights provided a linear relationship describing the metabolic rates of the control and poisoned fish. The slope representing the controls was 1.12, indicating a metabolic rate function of the weight of the fish, whereas the slope representing the cyanide-poisoned group was 0.67, thus describing a metabolism proportional to the surface area of the fish.

This study brings to light the determining influence of factors modifying the metabolic rate, such as exercise and size, on the response of fish to a toxicant.
Heavy Metal Stress and Increased Susceptibility of Steelhead Trout (Salmo gairdneri) to Yersinia ruckeri Infection
Authors: Knittel MD
Published: March 2009

Steelhead trout exposed to zinc concentrations as high 98 ppb did not demonstrate increased susceptibility to Yersinia ruckeri infection. Exposure to cadmium at 0.9 ppb did enhance susceptibility to infection; however, the exposure level was near the LC50 for cadmium against steelhead trout.

Exposure of steelhead trout to copper concentrations as low as 2.0 ppb, which is considerably below the LC50 for steelhead trout, increased their susceptibility to Y. ruckeri infection. The time of exposure to the 10 ppb copper showed that maximum infection occurred after 48 h of exposure; however, a 12-h exposure could increase infection in the host fish.

Results of this research show that the study of specific stress in fish caused by exposure to certain toxicants may be best studied by determining their susceptibility to a pathogen.
Use of an Unsignalled Avoidance Technique to Evaluate the Effects of the Herbicide 2,4-Dichlorophenoxyacetic Acid on Goldfish
Authors: Rand GM , Barthalmus GT
Published: March 2009

This study investigated the use of an unsignalled continuous avoidance technique to evaluate the subacute effects of 2,4-dichlorophenoxyacetic acid (2,4-D amine) on conditioned avoidance learning in goldfish. Goldfish were exposed to 20 ppm of 2,4-D for either 24 h or 2 weeks at different times during conditioning. The results indicate no significant differences between the controls and the fish exposed for 24 h on the ninth day of conditioning. However, fish treated for 24 h on the first day of conditioning exhibited differences in the magnitude of avoidance responding. In addition, fish exposed for 2 weeks showed significant differences in the pattern, rate of acquisition, and maintenance of the avoidance baseline. Behavioral differences also persisted during a postexposure period in the fish exposed for 2 weeks. This study illustrates the sensitivity of the unsignalled avoidance technique in evaluating conditioned avoidance behavior of fish.
Acute and Chronic Effects of Dimilin on Survival and Reproduction of Mysidopsis bahia
Authors: Nimmo DR , Hamaker TL , Moore JC , Wood RA
Published: March 2009

Dimilin (diflubenzuron), a new insecticide that inhibits chitin synthesis in insects, was found to be acutely and chronically toxic to an estuarine mysid shrimp, Mysidopsis bahia. The 96-h LC50 was 2.06 µg/litre, the 21-day LC50 1.24 µg/litre. Significantly, a 28-day exposure to an estimated concentration of 0.075 µg/litre decreased the production of offspring per female mysid. Data from the chronic tests suggest that the test concentrations not only decreased reproduction in the parents but also affected the reproduction of the progeny. The loss in reproductive success occurred even when the exposed parents or progeny had been moved to water that contained no Dimilin. Should Dimilin reach estuarine waters, the larval or the juvenile stages of other nontarget estuarine crustaceans may be threatened in a manner similar to that observed with M. bahia.
A Dynamic Photoelastic Study of Crack Propagation in a Ring Specimen
Authors: Dally JW , Shukla A , Kobayashi T
Published: March 2009

Crack propagation in a thick-walled ring specimen subjected to a mechanically simulated thermal stress was investigated by employing dynamic photoelasticity. Ring models fabricated from Homalite 100 were loaded with a specially designed mechanical deformeter which separated and rotated a slit cut into the ring to produce a combination of tension and bending that simulated a steady-state thermal stress.

Short starter cracks were machined into a series of ring models and the deformeter adjusted to give KQ/K1m ranging from 1.2 to 3.0. The crack was initiated and high-speed photographs of the isochromatic fringe loops at the tip of the running crack were recorded. The data were analyzed to obtain the instantaneous stress-intensity factor K, the normalized crack position a/w, and the crack velocity ˙a.

The relation between K and ˙a was established for Homalite 100 using the ring specimen. It was noted that this K-˙a relation compared well with those determined previously using single edge notch, rectangular double cantilever beam, contoured double cantilever beam, and modified compact tension specimens.

A comparison of K, as a function of position a/w, was made between static and dynamic crack growth. A marked difference was noted. For static crack growth, K increases with a/w until a/w = 0.2 and then decreases with further crack extension. For dynamic crack growth, K decreased monotonically with increasing a/w.
Comparison of Crack Arrest Methodologies
Authors: Crosley PB , Ripling EJ
Published: March 2009

The ASTM Cooperative Test Program data are used to compare the static (KIa) and dynamic (KId, KIdm) approaches to crack arrest. It is shown that KIa is not dependent on KQ. This is consistent with the requirements of the static approach, but not the dynamic one, which requires that KIa decrease with KQ if KId (=KIdm) is a constant. KId increases systematically with KQ at a rate that is consistent with calculations based on the use of a constant value for KIa which is equal to its measured mean value. Only in the limiting case of very short crack jumps (associated with very-low-average crack speeds) can KId be identified as a minimum value at which KId = KIdm. In this case KIdm ≈ KIa ≈ KIm. The latter is the idealized minimum value of K that will support the continued propagation of a running crack.
Some Comments on Dynamic Crack Propagation in a High-Strength Steel
Authors: Bílek Z
Published: March 2009

The dependence of the dynamic plane-strain fracture toughness, KId, on crack velocity was measured for propagating cracks in SAE4340 steel at room temperature. It has been shown that KId for SAE4340 steel in the quenched-and-tempered condition increases slowly for increasing crack velocity up to ˙a ≈ 100 m/s and then increases sharply above 100 MNm−3/2 at ˙a > 1000 m/s.
A Cooperative Program for Evaluating Crack Arrest Testing Methods
Authors: Hahn GT , Hoagland RG , Rosenfield AR , Barnes CR
Published: March 2009

Early and incomplete results of a multilaboratory test program examining two procedures for measuring crack arrest toughness are presented. The program involves 30 laboratories, with each participant conducting 10 tests, including eight of a common heat of A533B steel. The preliminary results are encouraging. No special difficulties in applying the test procedures have been encountered and the test specimens are performing satisfactorily. The results appear to be quite reproducible. Crack arrest toughness values derived from the two procedures with a static analysis agree closely, but values calculated using a dynamic analysis differ by about 50 percent. A possible source of this discrepancy is identified.
Critical Examination of Battelle Columbus Laboratory Crack Arrest Toughness Measurement Procedure
Authors: Fourney WL , Kobayashi T
Published: March 2009

Two procedures to characterize crack arrest toughness have been proposed to the ASTM E24.03.04 Committee for possible adoption as a testing standard. One of the procedures, proposed by Battelle Columbus Laboratory (BCL), uses results from a dynamic computer code based on an energy balance criterion. This computer code is utilized to construct two reference curves which relate KID/KQ or KIDm with Δa/ao and V/co with Δa/ao. Here KID represents the plane-strain fast fracture toughness, KIDm the minimum value of plane-strain fast fracture toughness or plane-strain crack arrest toughness, KQ the initial stress intensity, V the crack velocity, co the bar wave velocity, Δa the crack jump distance, and ao the initial crack length.

With these two reference curves for a given specimen geometry and a knowledge of KQ, co, and Δa/ao, not only is the determination of the crack arrest toughness KIDm proposed but also the characterization of the stress-intensity factor and crack velocity relationship.

The authors have utilized a one-dimensional version of the computer code developed by BCL to examine the predicted crack behavior in Homalite 100 and have made comparisons with experimentally observed crack behavior. This paper discusses the following aspects:

1. Comparison of the predicted crack positions with experimentally observed positions for rectangular double cantilever beam (R-DCB) models.

2. Influence of the shape of the K versus crack velocity (˙a) relationship on the reference curves generated for the R-DCB geometry.

3. Examination and comparison of the BCL code-generated K-versus-˙a curve with the experimental curve for R-DCB and crack line loaded (CLL) compact specimens.

4. K levels and velocities predicted by the reference curves compared on a test-by-test basis with experimentally observed values.
Crack Arrest in Water-Cooled Reactor Pressure Vessels During Loss-of-Coolant Accident Conditions
Authors: Marston TU , Smith E , Stahlkopf KE
Published: March 2009

The current American Society of Mechanical Engineers Code procedure for crack arrest in a reactor vessel is based on a static linear elastic fracture mechanics analysis and the assumption that arrest occurs when the crack-tip stress intensification, KI, equals some critical value, KIa—the so-called crack arrest toughness. The paper argues that the conditions for crack arrest in a nuclear pressure vessel, when it is subjected to thermal stresses resulting from a hypothetical loss of coolant accident, can be demonstrated with the current Code method, provided that an appropriate value for KIa can be obtained from laboratory tests. The difficulties in selecting the appropriate value of KIa for this component analysis are highlighted, particular attention being given to the effect of test specimen geometry, crack jump length, and material variability. Against this background, the paper outlines a possible procedure for obtaining the appropriate KIa-value. It is emphasized that the viability of the approach may be highly dependent on the structure's characteristics, and an approach considering kinetic (dynamic) effects may be necessary for other crack arrest problems.
Influence of Selected Chelating Admixtures upon Concrete Cracking Due to Embedded Metal Corrosion
Authors: Yau S-S , Hartt WH
Published: March 2009

It has been considered by the present research that if the solubility limit for embedded metal corrosion products can be increased or the products retained in solution altogether, then development of tensile stresses within the concrete and resultant cracking should be prolonged or eliminated. Consequently, the influence of selected chelating agents, including TEA, EDTA, DPTA, HEDTA, and Chel-138, upon various concrete properties has been evaluated. Specific tests investigated (1) the influence of each agent upon iron solubility as a function of pH, (2) the influence of the various agents as admixtures upon concrete strength, (3) the effect of the chelating agents upon corrosion of steel in aqueous solutions of pH 10 and 12 with 0 and 0.1 percent sodium chloride, and (4) the influence of the agents upon time-to-cracking of reinforced concrete cylinders in an accelerated test. While results of tests in Categories 1 and 3 were encouraging, it was determined that the chelating additions reduced concrete compressive strength. Further, time-to-cracking of admixtured specimens was extended beyond that of standard (no admixture) ones only for HEDTA and Chel-138 and then only under certain test conditions. It is concluded that, while the concept of adding chelating agents to concrete to enhance cracking resistance may be sound, increased time-to-cracking was not generally observed because of reactions between the various admixtures and the concrete.
Corrosion of Steel in Internally Sealed Concrete Beams Under Load
Authors: Flick LD , Lloyd JP
Published: March 2009

The ability of internally sealed concrete to prevent corrosion in reinforcement under service conditions has not yet been established. To simulate service conditions, members containing flexural cracks under either static or repeated load and subjected to a period of flushing with fresh water were considered. Corrosion of the reinforcement was induced by daily applications of a 3 percent sodium chloride solution.

The results based on half-cell potentials showed that the corrosion of the reinforcement in internally sealed concrete exposed to salt water was dependent on the type of loading. Under static load, no corrosion of the steel occurred. Under repeated load, however, the corrosion of the steel in internally sealed beams and in beams of conventional concrete occurred at the same time. This indicates that internally sealed concrete may offer only limited protection for members subjected to repeated loads. The lack of correlation between half-cell potentials and rate of corrosion suggests that further research in this area is appropriate.
Passivation of Galvanized Reinforcement by Inhibitor Anions
Authors: Corderoy DJH , Herzog H
Published: March 2009

Concrete reinforced by galvanized reinforcing bars requires the addition of inhibitor anions to passivate the zinc; otherwise evolution of hydrogen reduces the bond strength. In the present study, zinc in saturated calcium hydroxide solution, which is the principal electrolyte formed on initial hydration of cement, was found to passivate in the presence of either sodium chromate or chromic oxide. In both cases chromate ions were reduced instead of water so that there was no evolution of hydrogen. The passive film consisted of zinc chromate and chromic oxide, but calcium hydroxo-zincate was also produced, which assisted in passivating the zinc surface. In the case of chromic oxide a smaller concentration of chromate ions was present and passivated the zinc to a lesser extent. While 70 ppm of sodium chromate was sufficient to passivate the zinc, at least 300 ppm of chromic oxide was necessary to achieve the same degree of passivation. Chloride ions in the presence of chromate ions compete for the zinc surface and a critical concentration of chromate is necessary. This observation has been correlated with the passivation of galvanized reinforcing bars in concrete and it is considered that passivation is best achieved by the addition of 70-ppm sodium chromate to the concrete mix.
Time Dependent Changes in Notch Stress/Notch Strain and Their Effects on Crack Initiation
Authors: Carroll JR
Published: March 2009

An analytical and experimental program was conducted to evaluate the time-dependent changes in the stress-strain state at stress concentrations. Load-time interaction effects on creep and stress relaxation were evaluated utilizing simple coupon, super-scale, and simplified stress concentration test specimens. Periods of sustained compression loads included in a load sequence or spectrum were shown to affect a reduction in specimen fatigue life due to creep and stress relaxation occurring during the hold period. Experiments were designed such that a quantitative assessment of time-dependent changes in both notch stress and notch strain was possible. Resulting data were used to formulate a creep and stress relaxation module for inclusion in an automated hysteresis fatigue analysis program. Agreement between experimental and predicted lives using the hysteresis analysis is significantly better than predictions using a linear analysis method.
Effects of Compressive Loads on Spectrum Fatigue Crack Growth Rate
Authors: Hsu TM , McGee WM
Published: March 2009

A procedure, which allows flight-simulation profiles to be applied under stress intensity factor control, was used to study effects of compressive-compressive load cycles on spectrum fatigue crack growth rate. This approach eliminates the maximum stress-intensity factor, Kmax, and its associated plastic-zone size as a variable within a given test, and allows a small amount of crack growth representing instantaneous conditions in conventional load control tests. Tests were performed on center-cracked 7075-T651 aluminum alloy specimens subjected to typical flight-spectra, simulating both transport and bomber airplanes. The results indicated that the number of compressive-compressive cycles has little effect on spectrum-crack-growth rate and that essentially the same results were produced by a single compressive load. It was also found that the crack growth rate was relatively insensitive to the magnitude of the compressive load. A saturated condition was reached at a fairly low load level. The sequence of overload-comprensive load was also evaluated. For low stress intensity factor, the crack growth rate obtained was slightly higher when the application of compressive loads preceded an overload. However, the opposite occurred when the stress intensity factor was larger.
An Engineering Model for Assessing Load Sequencing Effects
Authors: Wozumi JT , Spamer T , Lambert GE
Published: March 2009

An engineering model has been developed to assess the impact of load spectrum variables on fatigue crack growth in metal structures. The model is based on the effective stress concept of Willenborg et al and Gallagher et al, and has been extended to accommodate retardation/acceleration phenomena peculiar to transport spectra. Development was accomplished by consideration of basic principles and previously reported results of simple overload/underload spectrum testing. The model does not rely on additional empirical parameters except material constant amplitude crack-growth rates. Formulation is such that flight-by-flight crack growth may be assessed without recourse to cycle-by-cycle integration.

Predictive accuracy of the model was compared with the results of crack propagation testing conducted on 28 center-cracked 7075 and 2024 aluminum specimens subjected to transport wing and fin load spectra. Mission parameter variables investigated in this testing were: altitude, gross weight, flight duration, speed, and touch-and-go landings. Use of the model produced improved accuracy over that exhibited by other models currently in use in the industry. The capability of the model to accurately predict acceleration effects is considered unique.
Effect of Transport Aircraft Wing Loads Spectrum Variation on Crack Growth
Authors: Abelkis PR
Published: March 2009

The effect of spectrum loading variations on crack growth were evaluated analytically and experimentally using C-15, KC-10A, and DC-10 transport aircraft wing loads spectra and 7475, 2024, and 7075 aluminum alloys. A total of 134 spectrum variations were generated in the following categories: (1) baseline spectra; (2) mission mix; (3) sequence of missions; (4) individual flight length; (5) flight segments; (6) exceedances spectra; (7) design stress level or usage severity; (8) valley/peak coupling; (9) low-load truncation; (10) high infrequent loads; (11) clipping of large loads; (12) miscellaneous variations, including the effect of flight loads alleviation system; and (13) combined variations. Spectra were generated as random cycle-by-cycle, flight-by-flight loading sequences. Crack growth tests, with cracks starting as through-thickness or corner cracks on one side of a hole, were performed on 47 of these spectra.

Analysis to test correlation shows 40 percent or better accuracy 78 percent of the time. However, different crack growth models had to be used to match the three aircraft baseline spectra: linear (C-15 and DC-10) and modified generalized Willenborg (KC-10A). Crack growth due to spectrum loading, with respect to loads interaction effects, appears to be a function of retardation and acceleration phenomena. An analysis model, incorporating both of these phenomena, is needed to properly predict spectrum variation effects.

Largest effect on crack growth life due to spectrum variations, as measured in flight hours, was due to mission mix, flight length, design stress level or usage severity, high infrequent loads, load alleviation system, and a change from a wing type to a vertical tail type spectrum. Using spectra variations that could be expected in service, fleet-wide crack growth variations by factors in the neighborhood of 100 and 10 could be experienced, depending on whether a short-term or a long-term spectrum variation is considered.
Evaluating Spectrum Effects in U.S. Air Force Attack/Fighter/Trainer Individual Aircraft Tracking
Authors: Larson CE , White DJ , Gray TD
Published: March 2009

The results of an analysis performed to evaluate damage rates at several locations in an airplane structure subjected to usage variations are presented. The results reveal not only the response of several locations to spectra variations, but also the correlation of damage rates at remote locations with the damage rate of a reference location.
Fundamentals of Radiographic Imaging
Authors: Halmshaw R
Published: March 2009

The fundamentals of radiological imaging on film can be considered in terms of contrast, sharpness, and graininess. On a fluoroscopic image, screen luminance and the performance of the eye at different luminances must also be taken into account. Modern methods of treating this subject using optical transfer function data are detailed and this is related to radiographic image quality. The significance of quantum fluctuation effects is discussed. Some data obtained from practical applications of real-time imaging techniques are detailed.
Radiation Sources and Detectors
Authors: Polansky D
Published: March 2009

Some characteristics of radiation sources, such as X-rays, electrons, protons, and neutrons used in the nondestructive testing of material, are presented. Detailed information on the quality of inspection possible with X-rays is also presented.

The different types of detectors such as ionization chambers and solid-state detectors are briefly reviewed, while a detailed presentation is made of the characteristics of film. The capability of the radiographic system as described in specifications is presented as the measuring base for competitive methods of image analysis in nondestructive test systems.
Real-Time Radiographic Imaging for Submerged-Arc Welded Pipe
Authors: Rudolph RG , Henry EB
Published: March 2009

According to American Petroleum Institute (API) Standards 5L and 5LX, the longitudinal weld in submerged-arc-welded (SA-welded) pipe may be nondestructively inspected by either radiological or ultrasonic methods. Each method has particular merits for detection of the weld imperfections normally encountered; the ultrasonic method has high sensitivity to planar imperfections, and the radiographic method has high sensitivity to volumetric imperfections. Although both methods have proven capable of meeting customer requirements, recent specifications for pipelines in the Arctic and offshore require automatic ultrasonic inspection.

The trend toward ultrasonic inspection was anticipated; hence, there was sufficient lead time to study the effects that it would have on flaw discrimination and rejection rates and to develop an automatic system that could meet all current and anticipated requirements. This new inspection system combines ultrasonic and radiographic inspection units in a complementary manner, utilizing each to detect the type of weld imperfection to which each is most sensitive and without confirmation by the other. Thereby, the combined system will exceed the individual performance of either unit for the detection of weld imperfections.

To satisfy the design objectives for this new inspection system, the radiological portion was to be capable of displaying a consistent 2 percent 2T sensitivity image, equivalent to radiographic specifications. Accordingly, a reasearch effort was initiated to develop an improved fluoroscopic system design.

Analysis of the performance limitations for a wide variety of fluoroscopic system designs indicated that designs employing low-light-level television (TV) systems with direct X-ray to light conversion screens showed the best long-range potential for development. The concurrent development of scan-conversion equipment capable of storing and integrating TV images gave considerable impetus to this effort, and a new system design was proposed that would be capable of providing both improved real-time imaging and stored images and could meet the requirements of equivalent radiographic sensitivity.

This new fluoroscopic system design was developed through several prototypes. The final version, available through Inspection Technology, Inc., Twinsburg, Ohio, is now installed in two pipe mills for the inspection of SA-welds. These systems are used in conjunction with automatic ultrasonic inspection systems concurrently developed by U.S. Steel. They provide acceptable 2 percent 2T sensitivity, with additional features of automatic inspection data display, image integration on command, 35-mm film image recording, and correlated display of ultrasonic alarms on the TV monitor.

This paper describes the development of the fluoroscopic system, analyzes the critical system parameters, describes tests performed, and describes the results obtained.
Video Display of X-Ray Topographic Images for In-Process Inspection of Semiconductor Devices
Authors: Chikawa J
Published: March 2009

X-ray diffraction topography is a powerful tool for observing defects in crystals which are harmful for device performance. In order to overcome the tedious procedure of the photographic method, a technique for the direct viewing of topographic images was developed based on a television system using an X-ray-sensing lead oxidevidicon camera tube (resolution 25 μm). The diffracted intensity necessary for direct viewing was estimated by considering photon noise. The required intensity was obtained with a rotating molybdenum target X-ray generator which is operated at 60 kVp and 0.5 A with a focal spot size of 0.5 by 10 mm. In transmission topography, two regions of the crystal, each having a width of 1 mm, are seen on the picture monitor due to the Kα1 and Kα2 radiation. By moving both the crystal and the TV camera and storing the Kα1 images consecutively in an image storage tube, a topograph with an area of 13 by 9 mm can be synthesized in 3 to 10 s. This storage improves the image quality and results in a signal-to-noise ratio of about 10 for individual dislocation images in silicon crystals. For low-intensity images, as observed for higher-order reflections, the signal-to-noise ratio of the images was improved by the storage of images on the target layer of the vidicon tube. Alignment of the specimen can be made easily and safely with remote control by viewing the TV images. It is possible to perform all procedures from specimen setting to image recording within a few minutes. The imaging system is applicable to dynamic investigation of defect generation. The capability is demonstrated by some observations of moving dislocations and growth processes of silicon crystals.
Real-Time Digital Image Processing for Radiological Imaging
Authors: Mengers P
Published: March 2009

Advances in semiconductor memory and microprocessor technology combined with significant cost reductions for these devices have made it technically feasible to develop high-speed, high-performance, stand-alone digital imaging equipment.

The paper describes the design and operation of a digital image processing unit that provides several significant image improvement capabilities especially important to radiological imaging.

Among these capabilities are noise averaging, image differencing or comparison, contrast transfer modification, spatial filtering, and edge enhancement. Most of these operations are performed at television rates in real time without resort to off-line processing in an associated computer. However, the units own random-access digital memory can be time-shared with an external central processing unit for additional processing through software.

Examples of application to X-ray and neutron radiography are presented, including processing of very-low-contrast imagery. The discussion includes also an analysis of the signal-to-noise ratio improvement that is attainable with equipment of this type.
Cylindrical-Scanning Transaxial Roentgen Tomography of High Temporal Resolution
Authors: Ritman EL , Robb RA , Harris LD , Kinsey JH , Gilbert BK , Smith KT , Wood EH
Published: March 2009

A prototype multiple X-ray source computerized transaxial tomographic system called the Dynamic Spatial Reconstructor (DSR) is currently being fabricated. This system is to consist of 28 X-ray sources arranged in a semicircle with 28 corresponding image intensifier/image isocon imaging chains arranged along an opposing semicircle. This entire system will permit mathematical reconstruction imaging of a cylindrical three-dimensional volume 23 cm axially and 30-cm diameter transaxially. This entire volume can be scanned in various ways ranging from the high “temporal resolution” (10 ms repeated 60/s), spatial resolution [full width half maximum (FWHM) 6 mm axially and transaxially], and “density resolution” (10 percent of roentgen opacity of water) to longer scan durations (for example, 100 ms up to a maximum of 2 s) with associated increases in spatial or density resolution or both.

It is anticipated that in addition to providing much needed information about optimal scanning configuration needs and requirements for different biomedical questions, the DSR is expected to be particularly useful in quantitation of the dynamic structure, function, and perfusion of the heart, lungs, and other organs.
Air Infiltration: A Review of Some Existing Measurement Techniques and Data
Authors: Hunt CM
Published: March 2009

This paper reviews the state of the art in the measurement of ventilation and air infiltration. It considers tracer gas techniques and discusses some of the tracer gases used as well as some of the potential sources of error. It also discusses fan pressurization-evacuation procedures for measuring building tightness and compares fan and tracer measurements. It discusses the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) crack method. It also considers a number of factors influencing infiltration rates and finally reviews a few of the empirical equations that have been developed to correlate infiltration rate with wind velocity and inside-outside temperature difference.
Residential Air Pollution Levels: Observation and Data Interpretation
Authors: Moschandreas DJ , Stark JWC , McFadden JE , Morse SS
Published: March 2009

A program to characterize the air quality in the residential environment has been undertaken. The generation of the data base, the interpretation of the data, and the formulation and application of an indoor-outdoor numerical model will be discussed.

Pollutant concentrations are sampled in three indoor locations and one outdoor location. “Instantaneous” readings are obtained for carbon monoxide (CO), nitric oxide (NO), nitrogen dioxide (NO2), ozone O3, sulfur dioxide (SO2), total hydrocarbons (THC), methane (CH4), and carbon dioxide (CO2); 24-h averages are monitored for total suspended particulate (TSP) and respirable suspended particulate (RSP) matter, sulfates, nitrates, lead and organics; aldehydes are sampled on a 4-h basis. In addition, the meteorological conditions both indoors and outdoors are measured, and the air exchange rate of each residence is experimentally determined. Elemental analysis is performed by proton-induced X-ray emission (PIXE). Finally, the kilowatt hours for heating, cooking and alternate current; the furnace efficiency; structural specifications; and other energy parameters are measured. The objective of this project is to develop causal relationships between the energy conservation measures-indoor (residential) air pollution concentrations and health effects.

Data analysis shows that the national ambient standards have been violated in the indoor residential environment for two pollutants, ozone and nonmethane hydrocarbons. Additionally, the American Society for Heating, Refrigerating, and Air-Conditioning Engineers' (ASHRAE) recommended indoor air pollution standards are violated by the following pollutants: carbon dioxide, total suspended particulate matter, and aldehydes.

A numerical model relating indoor and outdoor air pollution levels has been developed for the project. The model has been validated with the large data base sampled in the field studies. A series of numerical simulations indicate that under certain conditions energy conserving measures will increase the indoor air pollution levels.
Significance of Air Infiltration on Building Energy Conservation Design, Standards, and Codes
Authors: Ross HD
Published: March 2009

Air infiltration in residences accounts for 30 to 75 percent of the heating load, and present design procedures in commercial buildings result in excessive amounts of controlled fresh air introduction to offset air exfiltration losses. Simulation studies on retrofit potential of residences reveal that, while portions of the building heating and cooling loads can be reduced substantially using cost-effective techniques, air infiltration remains a dominant factor in the loads.

With the advent of a priority status for energy conservation, many new standards have been developed. These standards have been of three primary natures: prescriptive, component performance, and performance. Because new residential designs are making buildings tighter, with less air infiltration, three new standards are necessary to follow the trend in design. These standards are: (1) the use of pressurization-evacuation test methods to set a construction quality performance standard, (2) the use of ducted outside air with heat recovery for fresh air introduction to super-tight residences, and (3) the use of ducted outside air to fossil-fuel burning units for combustion purposes.
Guideline Considerations for Selecting Analytical Methods and for Cost Analysis Associated with Monitoring Waters Associated with Alternative Fossil Fuel Technologies
Authors: Rolan RG , Busacca M , Kangas MJ , Mezga LJ , Cornett CL , Faller A
Published: March 2009

Considerations for developing detailed environmental monitoring plans are described for fossil energy research, development, and demonstration facilities funded by the U.S. Department of Energy (DOE); this approach applies as well to other fossil energy technologies not currently funded by the DOE.

This paper focuses on a systematic approach to technical and cost aspects of methods selection for chemical, physical, biological, and support parameters. Emphasis is placed on methods selection for inorganic and organic chemical parameters for both process and ambient waters.
Organic and Inorganic Analysis of Constituents in Water Produced During In Situ Combustion Experiments for the Recovery of Tar Sands
Authors: Barbour FA , Guffey FD
Published: March 2009

The characterization of waters produced during in situ combustion of a tar sand deposit near Vernal, Utah, is presented. The water samples were collected during two different field experiments. Analysis of the inorganic constituents by standard methods indicated that ammonium, sulfate, and chloride were the predominant ions. Fractions of the organic material, defined as acid and base extracts, were obtained by liquid-liquid extraction using ethyl ether. Gravimetrically, the acid extracts comprised more than 70 percent of the extractable organic material. Identification of the components in the acid extracts was accomplished by using combined gas chromatography-mass spectroscopy (GC-MS) after methylation with diazomethane. The base extracts were found to be more complex and could not be studied directly with GC-MS. Of the major organic compounds identified, carboxylic acids, particularly acetic acid, were found to be the most abundant. Phenols, lactones, and pyridines were also identified.
Contribution of Thiosulfate to Chemical and Biochemical Oxygen Demand in Oil Shale Process Wastewater
Authors: Wong AL , Mercer BW
Published: March 2009

Thiosulfate accounted for a significant portion of the chemical oxygen demand (COD) (7 to 20 percent) and the biochemical oxygen demand (BOD) (14 to 41 percent) of the four oil shale process waters studied. Accurate measurement of the thiosulfate oxygen demand of retort water is critical in assessing its environmental impacts on receiving waters and in designing biological treatment systems to treat it. The contribution of thiosulfate to the COD of oil shale retort waters can be accurately measured in a standard COD test. The BOD of thiosulfate in retort water is more difficult to determine and may require the development of a special thiosulfate-acclimated seed. Thiosulfate recovery of a known thiosulfate spike ranged from 92 to 100 percent in the COD test and from 54 to 119 percent in the BOD test. Considerable variability in recovery was found between the process waters studied. When determining the BOD of oil shale process waters, care must be taken to insure that there is a viable population of thiosulfate-oxidizing bacteria.
Identification of Components in Aqueous Effluents Associated with New Coal Technologies and Geothermal Energy Sources
Authors: Gebhart JE , Segesta RM , Rando LC
Published: March 2009

Aqueous effluents from a coal gasification operation and from a geothermal energy process were analyzed using established procedures. The results of the analysis for metals by spark source mass spectrometry are given. This report stresses the identification of organic compounds in the sample by combined gas chromatography-mass spectrometry and computerized spectral matching techniques.
Evaluation of Utility Wastes for Hazardous Waste Potential
Authors: Weeter DW , Phillips HL
Published: March 2009

Recently, it has been recognized that coal ashes and scrubber sludges contain a variety of materials, which, if released in soluble form from a disposal area, could be damaging to the quality of surface and subsurface water. The Resource Conservation and Recovery Act of 1976 (RCRA) places these wastes in a special category. There will be stringent controls placed upon their disposal in the future unless it can be shown that hazardous materials, such as heavy metals, will not leach from disposal areas. Fixation is one potential means of limiting the release of materials.

Two toxicant extraction procedures and agitation with unbuffered deionized water were compared on the basis of heavy metal concentrations of the leachate when these treatments were applied to a fixed (crushed and uncrushed) and unfixed dry additive scrubber waste.

Comparison of the methods indicates that the buffering capacity of a waste, as well as its physical structure, determines the magnitude of heavy metals release. It was found that while fixation may reduce the permeability and surface area-to-volume ratio of a waste, the pH-solubility phenomenon is a controlling factor in some cases for the concentration of metals in simulated leachates.
Determination of Aromatic Hydrocarbons in Biologically Treated Water from a Coal Gasification Process
Authors: Dark WA
Published: March 2009

A high-performance liquid chromatography gradient scheme has been used to separate the aromatic hydrocarbons in the aqueous effluents of a coal gasification process. Samples of raw water, activated sludge, and activated sludge plus carbon-treated effluents were evaluated. By using a simple chromatographic concentration step before separation, the detection of aromatics below the parts-per-million level can be done routinely. Employing multiple detectors aids in peak identification.

The use of activated sludge plus activated charcoal was highly effective in removing aromatic hydrocarbons from the aqueous effluent of this gasifer. The final treated effluent contained some hydroxy-substituted multiring aromatics that were not removed by these treatments.
Comparison of Analytical Methods for Phenols, Cyanide, and Sulfate as Applied to Groundwater Samples from Underground Coal Gasification Sites
Authors: Wang FT
Published: March 2009

Groundwater samples, obtained near two underground coal gasification experiment sites, have been analyzed for phenols, cyanide, and sulfate. The samples were analyzed in the field; they were also preserved and sent to remote laboratories for analysis. Comparisons of the results have shown that the agreement between laboratory and field analyses is fairly good. This indicates that the methods of preservation are effective for these types of groundwater samples and that field analysis gives reliable information.
Gas Chromatographic and Mass Spectrometric Analysis of Volatile Organics in the Atmosphere
Authors: Sievers RE , Barkley RM , Denney DW , Harvey SD , Roberts JM , Bollinger MJ , Delany AC
Published: March 2009

Trace-level vapor-phase organic components in tropospheric samples have been identified using combined glass capillary gas chromatography-mass spectrometry. Samples were collected on Tenax-GC sorbent from an aircraft sampling port at various locations over North America and the Atlantic and Pacific Oceans. The compounds found in these samples include n-alkanes (hexane to pentadecane), alkenes, benzene and alkylbenzenes, styrene, tetrachloroethylene, dichlorobenzenes, dimethyldisulfide, and benzaldehyde. The concentrations of benzene and toluene were determined to be in the range of <0.1 to 1.3 ppb and <0.1 to 5 ppb, respectively. These values are comparable to those found for land-based samples.
Analysis of Organic, Elemental, and Carbonate Carbon in Ambient Aerosols
Authors: Johnson RL , Shah JJ , Huntzicker JJ
Published: March 2009

A method has been developed for the analysis of organic, elemental, and carbonate carbon in ambient aerosols collected on glass-fiber or quartz-fiber filters. The organic analysis proceeds in two steps. The filter is first heated in an oxygen (2 percent)-helium atmosphere at 340°C to volatilize the bulk of the organic carbon. The volatilized carbon passes through a manganese dioxide (MnO2) bed at 900°C and is converted to carbon dioxide (CO2), which is reduced to methane (CH4) and measured in a flame ionization detector. After the oven has been purged with helium, the oven temperature is raised to 600°C, and a secondary volatilization of organic carbon results. This is measured by the technique just described. The purpose of the two-step organic measurement is to minimize the pyrolytic conversion of organic to elemental carbon during the organic carbon analysis. For typical filter samples, approximately two thirds of the organic carbon is removed in the 340°C oxygen-helium step. The elemental carbon is then measured by combusting the sample in an oxygen-helium atmosphere at 600°C and measuring the evolved CO2 as described. A second combustion at 700°C in the oxygen-helium atmosphere is included to ensure complete recovery of the elemental carbon. The carbonates are measured by acidification of the filter and measurement of the resultant CO2. Because there is still some conversion of organic to elemental carbon during the organic analysis, the values for organic carbon and elemental carbon must be considered as lower and upper limits, respectively. An optical technique is being refined to permit a quantitative determination of the degree of conversion.
Laser Techniques for Analysis of Ambient Air
Authors: Gelbwachs JA , Jones PF
Published: March 2009

Laser techniques based on Raman scattering, absorption, and fluorescence have been used successfully in analyzing ambient air samples, as well as in probing plumes remotely. The sensitivity limits have ranged from 1 ppm to 0.02 ppb for air samples and down to 50 ppb for probing at a distance of 1 km in the lower portion of the atmosphere. When the appropriate lasers are available, long-path infrared (IR) absorption with wavelength modulation is the most sensitive technique, but fluorescence detection is often simpler. Of the newer techniques under investigation, multiphoton photoionization should have the potential for the lowest detection limits—one molecule in the laser beam or 103 to 104 molecules/cm3.
Correlation of Air Concentrations and Biological Data
Authors: Pendergrass JA
Published: March 2009

Finding an accurate means of evaluating worker exposure to hazardous materials has been the goal of industrial hygiene. The measurement of workroom contaminant levels has been and will continue to be a primary element of hazard evaluation. Biological data are also important factors that permit more complete evaluations. This presentation reviews studies that demonstrate useful techniques and parameters for correlating air samples and bioassays.
Sampling Rates and Other Considerations for Selected Passive Air Sampling Techniques
Authors: Palmes ED
Published: March 2009

Passive samplers for gases use the motion of the gas molecules themselves to furnish the energy for the transfer of gases from the ambient air to a suitable collecting medium. There is no need for pumps, flow regulators, batteries, or other power supplies. Thus the passive sampler can be made much smaller, lighter, less expensive, and much simpler to use and maintain than active samplers. However, passive samplers cannot be used to sample particulates, which, at the particle sizes encountered in industrial or community air, have coefficients of diffusion that are many orders of magnitude lower than those for gas molecules.

All passive samplers depend on Fick's first law of diffusion, which, paraphrased, states that the sampling rate is directly proportional to the coefficients of diffusion of the gas being sampled, the cross-sectional area of the diffusion path, and the concentration of the gas; it is inversely proportional to the length of the diffusion path.

There are two major types of diffusion samplers currently described in the literature. One type uses an air column as the diffusion barrier. Since the coefficient of diffusion for a gas in air is a constant that can be calculated independently, the area and length of the diffusion path, that is, the sampler geometry, can be chosen to give a suitable sampling rate. The other type uses a thin membrane as the diffusion barrier. At the present state of the art, permeation constants for gases through specific membrane materials cannot be calculated from the data available in the literature. Therefore, the permeation devices currently in use depend on empirical calibration of a specific membrane and a specific absorbent for each gas.

A wide variety of sampling rates can be obtained by using passive samplers, but each sampler operates at a fixed rate. The question of which sampling rates or ranges are the most desirable deserves serious attention by industrial hygienists.