bluuebunny/crossref_metadata_2025 huggingface dataset:
Surrogate Screening for Volatile Organics in Contaminated Media
Authors: Pojasek RB , Scott MF
Published: March 2009

Waste and spill site investigations often involve the need for a significant number of expensive analyses. The most mobile chemical species involved in most of these studies are volatile organic solvents. Often the cost for this portion of the investigation may approach anywhere from 30 to 50 percent of the total project cost. There is a clear need to develop surrogate testing protocols for these sites.

The philosophy behind the surrogate testing approach is simple. If one could reliably screen the site rapidly, taking 30 to 100 discrete analyses in a day, it would be possible to determine locations where specimen testing should be conducted. This approach also can be used to rank order randomly selected specimens so that the more meaningful specimens can be analyzed first. While the philosophy is simple, conducting a surrogate testing program needs very careful attention. Maximum specimen throughput must be carefully balanced by attaining the minimum chance for operator error.

Surrogate screening for volatile organics in soil and residues is described. A relatively inexpensive test was developed to allow screening of a large number of specimens for volatile organic solvents to determine locations where more detailed analyses, for example, gas chromatography/mass spectrometry (GC/MS) purge and trap techniques, could be used. Preserved specimens are ultrasonically homogenized with organic-free water in a screw-cap vial. A portion is withdrawn and placed in a second vial, where the septum is sealed with mercury, and equilibrated at 70°C (158°F) in an inverted position. A head space specimen is obtained from the vial, and injected onto a gas chromatograph (GC) column run on a fast elute isothermal or temperature program basis. The resulting plot is integrated for total peak areas and compared to standards.
Geotechnical Testing Considerations in the Determination of Laboratory Permeability for Hazardous Waste Disposal Siting
Authors: Zimmie TF
Published: March 2009

The paper deals with the laboratory determination of permeability (hydraulic conductivity) as applied to hazardous waste disposal siting studies. Probably the most important hydrogeologic parameter in a hazardous waste siting study is permeability. It is also the most variable property of soils, and this variability causes many problems in the laboratory, especially in the fine-grained soils typically tested for hazardous waste siting studies.

The determination of seepage velocity is discussed, and the importance of the groundwater level for hazardous waste disposal sites is considered.

The best overall laboratory device to determine permeability appears to be the triaxial device, utilizing the proper application of backpressure. The use of rigid wall permeameters or consolidation theory to determine permeability is not recommended, since unconservative results are generally obtained.
Subsurface Investigation of Metal Sludge and Explosive Disposal Pond Areas
Authors: Phung HT , Bulot MW
Published: March 2009

A subsurface investigation at Area G (metal sludge) and O (explosives) ponds located in the Lone Star Ammunition Plant, Texarkana, Texas, was initiated. The study included review of existing data, site drilling, and sampling and analysis of soil and water.

Results indicate that the ponds are underlain by massive clay beds (aquiclude), and the potential for contamination of the usable ground water supply appears to be remote. No significant migration of hazardous contaminants through subsurface soils was observed.

Groundwater quality is poor due to high total dissolved solids (TDS) and soluble salt content. However, it is relatively free of trace metals, trinitrotoluene (TNT), cyclotrimethylenetrinitramine (RDX), and trace organics.

It is recommended that these ponds be closed and that appropriate post-closure maintenance and monitoring, as mandated under the Resource Conservation and Recovery Act, be implemented.
Application of Site-Specific Hazard Assessment Testing to Solid Wastes
Authors: Lee GF , Jones RA
Published: March 2009

The U.S. Environmental Protection Agency (U.S. EPA) proposes to use a leaching test as one of the criteria for estimating the environmental hazard of on-land disposal of hazardous wastes. There are many significant technical problems with the specific protocols proposed for use, such as not specifying a defined redox condition under which the tests are to be conducted. The most significant deficiency is in the proposed method for interpretation of leaching test results. The use of these tests as currently formulated could readily result in chemicals that present minimal risk to the environment and human health, being classified as hazardous. More importantly, their use could cause truly hazardous wastes to be classified as acceptable for on-land disposal with minimum restrictions. Adopting the U.S. EPA's proposed approach will result in unnecessarily large amounts of money being spent for control of “hazardous” chemicals and, in some cases, without providing adequate environmental or human health protection.

This paper reviews some of the problems associated with the use of the U.S. EPA Resource Conservation and Recovery Act (RCRA) leaching test for classifying the hazardous nature of chemicals destined for land disposal. Recommendations are made for modification of the RCRA leaching test, to provide for a site-specific evaluation procedure to more properly evaluate the potential hazard associated with on-land disposal of hazardous wastes. An approach is discussed which combines environmental physics (transport and mixing), chemistry-fate, and biology (toxicology, bioconcentration) information. This approach is presented as a basis for interpretation of the results of the leaching tests in terms of the hazard associated with the disposal of a particular waste at a particular site. This “hazard assessment approach,” which has been adapted for application to solid wastes by the authors, is a sequential, selective testing-interpretation scheme for combining information on environmental physics (transport and mixing), chemistry-fate, and biology (toxicology and bioconcentration) of a waste and disposal site to determine potential environmental hazard.
Processing and Mechanical Properties of Investment Cast Ti-6Al-4V ELI Alloy for Surgical Implants: A Progress Report
Authors: Smickley RJ , Bednarz LP
Published: March 2009

Recent advancements in the production of titanium alloy investment castings have enabled manufacturers to offer high-integrity net-shape components. Effective material utilization and attractive lead times for providing a finished product have fostered a growing interest in applying cast titanium technology to the production of surgical implant devices.

Howmet Turbine Components Corp., a major producer of titanium castings for the aerospace industry, is currently evaluating the potential of investment cast Ti-6Al-4V ELI alloy [ASTM Specification for Titanium 6Al-4V ELI Alloy for Surgical Implant Applications (F 136-79)] for surgical implant devices. Manufacturing processes such as hot isostatic pressing (HIP) and weld repair, vital to production of net-shape titanium alloy castings, have been evaluated for cast Ti-6Al-4V ELI material. Smooth and notched tensile properties, as well as impact and fatigue strength, have been investigated with favorable results.
High-Integrity Titanium Alloy Shapes by Powder Metallurgy
Authors: Eylon D , Froes FH
Published: March 2009

The use of titanium powder metallurgy (PM) products for high fatigue resistance applications is reevaluated in the light of new developments in titanium alloy powder making, contamination control, consolidation practices, postcompaction heat treatments, and alloy development. Nonmetallic inclusions and lamellar alpha microstructures were identified as contributing to lower fatigue life. The use of clean rotating electrode process (REP) powder and the press consolidation technique (to obtain more uniform low aspect ratio alpha structures) are already producing fatigue strengths as high as those of wrought products. More work is now under way to optimize the use of plasma REP powder (PREP), press consolidation, and alloys specifically designed for powder metallurgy. It is expected that in the very near future, titanium powder metallurgy will produce components of complex shape with lower cost and higher fatigue strength than wrought products.
Behavior of Commercially Pure Titanium and Ti-318 (Ti-6Al-4V) in Orthopedic Implants
Authors: Dobbs HS , Scales JT
Published: March 2009

At the Royal National Orthopaedic Hospital major replacement of long bones began in 1949, and the first titanium-containing endoprosthesis was inserted in 1964. By now over 250 titanium-containing endoprostheses of various kinds have been inserted. Most of these components were made on a modular basis and included sections of cast cobalt-chromium-molybdenum alloy. In 1972 titanium alloy 318 (Ti-318)(Ti-6Al-4V) was introduced, and this alloy largely replaced the previously used commercially pure titanium.

This paper presents our experiences with these endoprostheses, with titanium total hip replacements, and with other titanium devices. Using standard statistical methods, survival curves for the nonremoval of the component were obtained. These curves demonstrated that the performance of upper femoral, lower femoral, and upper tibial endoprostheses was slightly worse than that of standard total hip replacements. This worse performance was a result of five intramedullary stem fractures, but we now think that this problem has been overcome by the introduction of Ti-318. These and other fractures emphasize the importance of good design, good surface finish, and optimum stem or section size. There was no evidence that the combination within a single implant of cobalt-chromium-molybdenum and titanium, commercially pure or alloy, caused corrosion or clinically significant problems. Although blackening of adjacent tissue has been observed, there was no evidence that this was associated with an undesirable tissue response.
Analysis of a Titanium Alloy Total Hip Device
Authors: Lemons JE , Lucas LC , Buchanan RA , Compton RC
Published: March 2009

Retrospective microstructural analyses of four retrieved titanium and cobalt alloy total hip prostheses were conducted. The titanium alloy stem sections showed variable microstructures which could directly influence the alloy properties and thereby limit clinical longevities.
Titanium Implants with Porous Structures for Bone Ingrowth: A General Approach
Authors: Ducheyne P , Martens M , De Meester P , Mulier JC
Published: March 2009

Porous structures show substantial potential as attachment vehicles for permanent orthopedic implants. Data on the properties of porous titanium fiber and titanium wire mesh porous structures are presented. The strength and porosity requirements are reconciled by using a fully dense Ti-6Al-4V substrate coated with a porous surface. The authors show that this approach yields at least six advantages over other porous or porous-coated implant systems. Devising implants with a pressure-sintered wire mesh coating yields, in addition, the possibility of (1) increasing the mean pore size and retaining the strength, elasticity, structural integrity, and sintering ability of the porous coating; (2) decreasing the high sintering temperatures, which are detrimental to the strength and ductility of the substrate; and (3) obtaining a uniform and perfect bonding between the porous coating and the substrate.
A Single-Ply Transverse Tension Strength Test for Unidirectional Composites
Authors: Foye RL
Published: March 2009

Moisture content is a factor in the mechanical response of many composites. To evaluate this effect, it is necessary to achieve a controlled and uniform moisture distribution within each test specimen. Thin specimens reach moisture equilibrium quicker than thick ones, leading to shorter and more economical test programs. This paper presents the results of an initial attempt to develop a single-ply transverse tension test for unidirectional composites. A number of these tests were performed on unidirectional graphite composites. The transverse strengths were close to the thick specimen values. The stress distributions and the tensile buckling characteristics of the specimens were analyzed using NASTRAN.
Biaxial Testing of Graphite/Epoxy Laminates with Cracks
Authors: Daniel IM
Published: March 2009

An experimental investigation was conducted to study the behavior under biaxial tensile loading of graphite/epoxy plates with cracks and to determine the influence of crack length on failure. The specimens were 40 by 40-cm (16 by 16 in.) [0/±45/90]s laminates with cracks oriented at 30 deg to one side of the specimen. Four crack lengths, 2.54, 1.91, 1.27, and 0.64 cm (1.00, 0.75, 0.50, and 0.25 in.), were investigated. Deformations and strains were measured using strain gages, birefringent coatings, and moiré grids. The specimens were loaded in biaxial tension in a specially designed loading frame. Results were presented in terms of the ratio of the normal to the crack stress and the unnotched tensile strength of the laminate. This ratio was found to be approximately 21 percent below that for uniaxially loaded plates with transverse cracks, indicating an appreciable contribution to failure of the shear stress. This percentage of strength ratio reduction remained nearly the same for all crack sizes. Experimental results were compared satisfactorily with those predicted on the basis of a tensor polynomial failure criterion for the lamina and a progressive degradation model.
An Evaluation of the Sandwich Beam Compression Test Method for Composites
Authors: Shuart MJ
Published: March 2009

This report evaluates the sandwich beam in four-point bending as a compression test method for advanced composites. To accomplish this evaluation the test method was used to obtain preliminary compressive design data for the temperature range 117 to 589 K (−250 to 600°F) and was analyzed to determine any influence from the honeycomb core on composite mechanical properties. The [08], [908], [(±45)2]s, and [0/±45/90]s laminate orientations were investigated utilizing HTS1/PMR-15 graphite/polyimide composite material.

The experimental and analytical results indicated that the test method can be used to obtain compressive elastic constants for graphite/polyimide composites. Elastic data were obtained for a wide temperature range, although many failures were initiated by either load concentrations or top cover debonds. The analysis indicated that the honeycomb core had negligible effects on composite mechanical properties. The top cover carried essentially all the compressive load in the beam test section, and the stress state in the test section of the top cover was essentially uniform and uniaxial.
Stress Distribution in Sandwich Beams in Uniform Bending
Authors: Salamon NJ
Published: March 2009

The three-dimensional elastic stress state in a sandwich beam in uniform bending is given. The analysis is carried out numerically through use of a finite-difference formulation of the exact equations of elasticity. The beam is proportioned similar to one used in the characterization of composite materials and composed of [±45]s composite face sheets laminated to a typical honeycomb core. It is shown that interlaminar stresses are confined to boundary regions near the free edges and that the inplane stresses converge to the laminate theory solutions in the interior of the beam despite the fact that the beam is deeper than it is wide. Importantly, the core/face sheet tractions are found to be insignificant.
Cost-Effective Mechanical Property Characterization
Authors: Suarez JA
Published: March 2009

This paper describes current mechanical property characterization practices for advanced composites in automotive and primarily stiffness-critical aircraft secondary structure applications. The use of extensive costly test programs to develop statistically valid static and fatigue design allowables is avoided. Use is made of small property-characterization programs that make maximum use of cost-effective coupon-type specimens and that are tailored to the special application at hand.
Statistical Analysis of Fibrous Composite Strength Data
Authors: Tenn LF
Published: March 2009

Using standard statistical procedures, distributional forms for fibrous composite strength data are examined for goodness of fit. Six examples of strength data for epoxy reinforced with Kevlar 49, fiber glass, and Thornel 300 graphite fabrics, as well as unidirectional T300/5208 graphite/epoxy composites, were examined. The data were evaluated using the chi-square and Kolmogorov-Smirnov goodness-of-fit statistical tests and the correlation coefficient from linear regression analysis. The distributional forms tested were normal, log normal, 2-parameter Weibull, and 3-parameter Weibull. At the 5 percent significance level, none of these was rejected.
Mechanical Property Characterization of Intraply Hybrid Composites
Authors: Chamis CC , Lark RF , Sinclair JH
Published: March 2009

An investigation was conducted to characterize the mechanical properties of intraply hybrids made from graphite fiber/epoxy matrix (primary composites) hybridized with varying amounts of secondary composites made from S-glass or Kevlar 49 fibers. The tests were conducted using thin laminates having the same thickness. The specimens for these tests were instrumented with strain gages to determine stress-strain behavior. The results show that the mechanical properties of intraply hybrid composites can be measured using available test methods such as the 10-deg off-axis method for intralaminar shear, and conventional test methods for tensile, flexure, and Izod impact properties. Intraply hybrids have linear stress-strain curves to fracture for longitudinal tension and nonlinear stress-strain curves for intralaminar shear.

The results also showed that combinations of high-modulus graphite/S-glass/epoxy matrix composites exist which yield intraply hybrid laminates with the “best” balanced properties: for example, 100 percent increase in impact resistance and 35 percent increase in tensile and flexural strengths, with no reduction in modulus compared with graphite fiber/epoxy matrix composites. In addition, the results showed that the translation efficiency of mechanical properties from the constituent composites to intraply hybrids may be assessed using a simple equation.
Proof-Load Determination for Pressure Vessels Wound with Aramid Fiber
Authors: Hahn HT
Published: March 2009

The paper presents a method of determining the proof pressure that can guarantee a design lifetime for Kevlar-49/epoxy pressure vessels. The method is based on the assumption that, when taken from the same population, a statically strong vessel is also strong in stress rupture. The lifetime data available at higher pressures are extrapolated to estimate the lifetime distributions at lower pressures. In so doing, we assume that the lifetime distribution is exponential and that the characteristic lifetime is related exponentially to the applied pressure divided by the average burst pressure. Two examples are given to illustrate the method.
Environmental Effects on Composite Fracture Behavior
Authors: Porter TR
Published: March 2009

This paper describes the results of an experimental program investigating the effects of temperature and moisture on the damage development and fracture response of composite materials. Fracture data were obtained for graphite/epoxy composite materials that had been moisture-conditioned. The fracture response data were obtained for both room temperature and immediately after the application of a temperature transient causing the specimen to attain 150°C (300°F). Three 20-ply laminates were investigated in the tests: one typical angle-ply laminate, one laminate representative of polar/hoop-wound pressure vessels, and one laminate containing four plies of S-glass fibers representative of engine fan blades for propulsion systems. From the results it is shown that elevated temperature degrades the notched strength of some laminates while not degrading others. The unnotched strength of all laminates tested at elevated temperature was degraded. In addition to the fracture data, the influence of preloading on damage growth and moisture absorption, the effect of autoclave pressure during laminate cure on fracture, and the variation of interlaminar shear properties with layup, moisture exposure, laminate material, and cure pressure were investigated.
Effects of Liquids on the Stress-Rupture Lives of Fiber Glass-Reinforced Plastics
Authors: Hoa SV
Published: March 2009

The results of a preliminary investigation on the effect of liquid environments on the stress-rupture lives of fiber glass-reinforced plastics are investigated. Specimens made from sheet molding compounds were subjected to stresses while being immersed in water and in isooctane. At stresses greater than 50 percent of the ultimate tensile strength of the material, the stress rupture lives show a large amount of scatter. Immersion of the polymer in the liquids indicates considerable liquid absorption. Immersion of the specimens in water also decreases the amount of scatter. Microscopic observation reveals a multitude of irregularities of glass fiber protrusions at the surface of the specimens. The investigation is limited and serves as an indication for future research.
Review of Statistical Analyses of Fatigue Life Data Using One-Sided Lower Statistical Tolerance Limits
Authors: Little RE
Published: March 2009

This introductory paper explains basic probability concepts and summarizes in a fatigue context the state of the art for analyses of life data using one-sided lower statistical tolerance limits. Types I and II censoring are considered for both the two-parameter log-normal and Weibull distributions, and the corresponding approximate and exact one-sided lower tolerance limit calculations are illustrated and discussed. In addition, Antle's likelihood ratio test for discriminating between these two-parameter life distributions is summarized. The classic one-sided lower nonparametric tolerance limit analysis and a small sample modification by Little are discussed and illustrated in a fatigue context. Overall, this paper is intended to provide background and perspective for subsequent papers.
Reliability of Fatigue Testing
Authors: Young L , Ekvall JC
Published: March 2009

A statistical analysis was performed on fatigue test data for aluminum, titanium, steel, and nickel materials. The data for the titanium, steel, and nickel were obtained from spectrum fatigue tests, whereas the data for aluminum were obtained from both constant amplitude and spectrum fatigue tests. The analyzed data consisted of a total of 553 S-N test groups with 2417 specimens and 1288 spectrum test groups with approximately 5000 specimens.

The distribution of logarithmic standard deviation of fatigue life for these test groups was analyzed with normal, logarithmic, and two-parameter Weibull probability distribution functions and with 2-deg polynominal equations. The best fit was evaluated using the coefficient of correlation and the chi-squared goodness of fit test. None of the distribution functions or polynomial equations provided the best fit for all of the distributions of the logarithmic standard deviation of fatigue life for the selected sets of test groups. A comparison is also made of three methods of calculating scatter factors.
Statistical Fatigue Properties of Some Heat-Treated Steels for Machine Structural Use
Authors: Nishijima S
Published: March 2009

A practical method for establishing the P-S-N diagram is proposed. The method is essentially based on consideration of the distribution of strength deviation values for individual test data determined against the mean S-N curve of the population. Thus an S-N curve for 1 percent failure probability can be derived from the fatigue test results using 100 specimens.

A series of statistically planned fatigue tests was conducted according to the proposed method, in order to obtain basic fatigue data about different materials most commonly used in mechanical industries. This paper deals with the results for some typical carbon and low-alloy steels with different heat treatments, the tests being on smooth specimens in rotating bending, and discusses the variation in statistical properties between materials.
Maximum Likelihood Estimation of a Two-Segment Weibull Distribution for Fatigue Life
Authors: Chou PC , Miller H
Published: March 2009

A two-segment distribution is proposed for representation of the fatigue life of modern high-performance composite materials. Each segment is a two-parameter Weibull distribution. Equations of the maximum likelihood method in estimating parameters are derived, and an iterative solution scheme is presented. Several example problems are included.
Survey of Gas Turbine Synthetic Liquid Fuels
Authors: Amero RC , DeCorso SM , Thomas RL
Published: March 2009

As the United States moves toward an alternative fuel economy, away from petroleum fuels, gas turbines fueled by nonpetroleum sources are expected to supply an increasing percentage of the total generation of power. New technology and procurement standards need to be developed for these alternative fuels to ensure an operable, economical turbine-fuel system.

Recognizing this need, Subcommittee B133.7 on Gas Turbine Fuel Procurement Standards, a subcommittee of the American National Standards Institute (ANSI), carried out a survey to establish a technical framework for interpreting the projected properties of synthetic fuels for gas turbine applications. The 55 responses received from synthetic liquid fuel producers, equipment manufacturers, turbine users, and consultants, as well as government and nongovernment agencies, showed that process developers, gas turbine manufacturers, and users are actively involved in planning for future synthetic fuels. While the quality and properties of synthetic liquid fuels were not fully established, it is clear that methanol and distillate fuels derived from shale, coal, and tar sands are being seriously developed and will play a major role in future gas turbine operation.
Fuel Property Effects on the Performance of a Small Industrial Gas Turbine Engine
Authors: Caan W , Haasis JM , Williams RC
Published: March 2009

The effects of a wide variety of fuel types on the gaseous exhaust emissions, smoke, and particulates and on the combustor wall temperatures of a small industrial gas turbine engine are presented. The results were determined from evaluation tests conducted with the use of a single-shaft, constant-speed engine, rated at 534 kW, which employs a single, can-type combustor. The test fuels included a pure hydrocarbon, aviation gasoline, jet fuels, diesel fuel, fuel oils, an experimental broad-specification fuel, and a coal-derived fuel from the solvent-refined coal II (SRC-II) process. The hydrogen content of the fuels ranged from 9.1 to 16.1% by weight. Decreasing the fuel hydrogen content increased smoke emissions and combustor wall temperatures. The relationship between the mass concentration of exhaust particulates and the smoke number was similar for the coal-derived SRC-II and petroleum-based fuels. The combustion efficiency, determined from exhaust hydrocarbon and carbon monoxide emissions, did not change appreciably at any load condition for a wide range of fuel properties. The conversion of fuel-bound nitrogen to exhaust nitrogen oxides (NOx) was found to depend on the fuel nitrogen content and engine load. The conversion efficiencies were similar for the coal liquid, which was naturally high in fuel-bound nitrogen, and an artificially doped petroleum fuel.
Performance of SRC-II Fuels in Gas Turbine Combustors
Authors: Tong EH , Mellor AM
Published: March 2009

Jet A fuel, solvent-refined coal II (SRC-II) middle distillate, and a 50:50 volume percent blend of Jet A and SRC-II middle distillate were burned in laboratory combustion rigs to study the effects of fuel properties on combustion performance. Centerline soot concentration, flame radiation intensity, and lean blowoff measurements were made in combustors simulating conventional and prechamber geometry gas turbine combustors. A special ignition rig was used to obtain minimum ignition energies. The centerline soot concentrations and flame radiation intensities for the SRC-II-middle distillate and the blend were very similar and were higher than those for Jet A. Characteristic time models correlating lean blowoff and minimum ignition energies indicated that the chemical properties of the fuels appeared to have only minor effects on these performance areas.
Effect of Fuel Properties on Ignition and Combustion Limits in Gas Turbine Combustors
Authors: Odgers J , Kretschmer D
Published: March 2009

This review of reported ignition and stability phenomena indicates that the introduction of alternative fuels may create major problems for nonpremixed fuel systems unless measures are taken to prevent any increase in droplet size. Some methods for prediction of the effects of changes in fuel on the minimum ignition energy, blowout velocity, and weak extinction limit are given.
Corrosion of Fuel Handling System Materials by Coal-Derived Liquid Fuels
Authors: Doering HvonE , Haskell RW , Michelfelder T
Published: March 2009

During a gas turbine test program requiring large volumes of coal-derived liquid fuel, creosote oil, used as a substitute liquid coal synthetic fuel, caused metal corrosion in some of the fuel handling and storage components.

A subsequent laboratory test program with creosote oil and several coal liquid synthetic fuels showed that the lower boiling grades were corrosive to copper and somewhat corrosive to brass and zinc. These metals often are used in fuel pumps, flow dividers, and valves. The corrosion rate was higher with dynamic flow conditions than with static conditions. Iron was only slightly attacked by creosote oil in these tests.
Synthetic Fuels for Stationary Gas Turbines: A California Perspective
Authors: Anderson SJ , Jackson MD , Smith KD
Published: March 2009

The state of California currently depends extensively on imported oil and natural gas from other states and foreign countries. To ensure uninterrupted service to industrial and utility company engines, alternative fuels to petroleum are being investigated. Sponsored by the California Energy Commission, an evaluation was conducted by the Acurex Corp. of coal and coal-based fuels for use in stationary gas turbines. A broad range of coal-derived solids, gases, and liquids is reviewed in this paper. Candidate fuels are identified which do not affect engine operation or exceed California environmental regulations—particularly for nitrogen oxides (NOx) pollutants.

Beneficiated coals, which contain significant amounts of ash, cause unacceptable turbine blade erosion and corrosion problems. Therefore, coal solids cannot be considered viable turbine fuels at this time. However, many gas and liquid synthetic fuels exhibit handling and combustion characteristics similar to those of petroleum fuels. Only minor hardware modifications are necessary to burn these fuels. For fuels with high nitrogen content, such as unhydrotreated direct liquids, advanced combustors are required to control NOx emissions and to meet California's stringent environmental standards.

Methanol was selected as the preferred synthetic fuel. Methanol produces low emissions and requires only minor equipment changes. Testing is under way to quantify methanol's NOx emission characteristics.
Properties of Low-Btu Coal Gas and Its Combustion Products
Authors: Doering HvonE , Kimura GS , Smith DP
Published: March 2009

Operating results are presented for an air-blown, fixed-bed coal gasification system, operating in conjunction with a low-temperature acid-gas removal system and integrated with a full-flow pressurized gas combustion apparatus. This pilot-scale system simulated the major subsystems of an integrated gasification combined-cycle (IGCC) power plant. The overall plant emissions goals of >90% hydrogen sulfide removal were achieved, and gas particulate loadings of <4 ppm, with a gas alkali metal content of <20 ppb, were measured. Gas turbine combustion emissions of carbon monoxide and oxides of nitrogen are reported as functions of the combustor exit gas temperature.
Characterization of Ash Residues from a Refuse-Derived Fuel/Oil Combustion Study
Authors: Hasselriis F , Robbins CR
Published: March 2009

Inorganic residues of Eco-Fuel, a powdered refuse-derived fuel (RDF), ashed in the laboratory at various temperatures, and the slag and fouling resulting from co-firing this fuel with residual oil in a utility boiler were characterized by atomic absorption and X-ray powder diffractometry in order to observe the chemical and crystalline phase development of the RDF residues. The boiler equipment used in co-firing the RDF and the conditions of operation are related to the chemistry of the residues. The formation of sulfates in fly ash/fouling deposits indicated that there was absorption of sulfur from the RDF and oil. The fates of silicates, clays, quartz, and carbonates are noted in the slag and fouling samples and compared with those in laboratory ashing samples. Processing, which can remove glass from the RDF, would be expected to affect the nature of boiler slag and fouling. Thermal and chemical processing of RDF can alter the crystalline structure of the cellulose, as evidenced by X-ray analysis of several Eco-Fuel samples, thereby embrittling the cellulosic fibers and producing a relatively nonfibrous RDF. X-ray analysis of this sort is valuable because it reveals the phase development and chemical fate of elements, which is not indicated by atomic absorption analysis, and also helps the investigator to anticipate and understand the fouling characteristics of alternative fuels derived from municipal refuse and crop wastes.
Direct-Contact Cell-Culture Method
Authors: Smith LM
Published: March 2009

A direct-contact cell-culture test method has been developed to provide routine lot-to-lot biological assurance as a part of the quality assurance program during the manufacture and distribution of medical materials and sterile-packaged human-implant devices. It is particularly useful for detecting trace ethylene oxide or catalyst residuals. The method has also been used routinely to provide a first biocompatibility evaluation of proposed new materials or formulation.

Specimens are placed in direct contact with human fibroblastic cells grown to a confluent monolayer. The results are evaluated microscopically after 24 h incubation, using appropriate positive and negative controls. An alteration in cellular morphology is considered a cytopathic effect (CPE). Implant materials and devices are approved by the quality assurance department only if they produce no CPE in this test.

This test method has been used continuously in the lot-to-lot quality assurance program at Dow Corning's Medical Products Plant for more than ten years and has provided a fast, reliable, highly sensitive, and inexpensive method for evaluation of biocompatibility.
Test Method for Human Cell-Culture Elution to Evaluate Medical Materials and Devices for Cytotoxicity
Authors: Ettorre LM , Phillips K
Published: March 2009

Tissue-culture testing used for screening selected new-components as well as for lot-to-lot testing of designated incoming materials before approval for use is performed routinely by the employees of the Microbiology Department at Extracorporeal, Inc. The “extraction method,” which uses the WI-38 cell line, is used most often. MRC-5 cells, a similar cell line, are also maintained as an alternate.

Materials are extracted on a surface area or weight ratio basis at 37°C for 24 h. The growth media is aspirated from the plates, replaced with extracting media, and incubated at 37°C for 24 h. Plates are stained, dried, and examined under a light microscope. Cytotoxicity is scored on a scale of 0 (negative response) to 4 (more than 75% of cells morphologically changed). Results of +2 to +4 are considered cytotoxic. Retesting is done to verify cytotoxic results.
Evaluation of Materials Used for the Fabrication of Medical Devices: Cytotoxicity Testing
Authors: Horres CR , Mears HG , Wilsnack RE , Moore GE
Published: March 2009

Becton Dickinson has been involved in cell-culture testing of medical devices for the past ten years using WI-38 cells as a human origin in vitro target system. Two modes of tissue-culture testing are used at Becton Dickinson: cytotoxicity score and inhibition of cell growth. To determine score, cell monolayers are scored microscopically as to the degree of morphologically discernable cytotoxicity after incubation for 24 and 72 h with culture media used to eluate test materials. Inhibition of cell growth is determined by culturing cells for 24 h in test material eluate then trypsinizing and reseeding using the elution fluids as growth menstruum. The plates are incubated, and when negative controls indicate a 100% monolayer, the cell monolayers are fixed and stained. The cells are scored microscopically as to the percent of growth inhibition in relation to the negative control. This system has provided a sensitive, reproducible, and short duration evaluation mechanism for biomaterials.
Primary Acute Toxicity Screen for Biomaterials: Rationale, In Vitro/In Vivo Relationship and Interlaboratory Performance
Authors: Dillingham EO
Published: March 2009

Correlation analysis of in vitro and in vivo toxic response to biomaterials, based on tests done directly on the materials and the material extracts (water, saline, polyethylene glycol-400, and cottonseed oil), demonstrated significant in vitro/in vivo correlations. In vitro tests that most strongly correlated with in vivo tests were inhibition of cell growth, hemolysis, and agar overlay tissue culture (zone index for test directly on the material). In vivo tests that most strongly correlated with in vitro tests were intradermal irritation (cottonseed oil and polyethylene glycol-400 extracts), systemic toxicity (cottonseed oil and polyethylene glycol-400 extracts of high toxicity materials), and intramuscular implantation (gross rating of the material implant). In vitro and in vivo toxicity ratings were correlated with histopathologic tissue response to material implants (necrosis [coagulative necrosis and overall degree of necrosis], inflammatory cellular infiltrates [polymorphonuclear leukocytes, macrophages, and giant cells], and fibroendothelial proliferation), although the correlations were lower than for the primary screen tests per se.

Interlaboratory performance of the primary screen indicated a useful degree of discrimination of the toxicity of different materials; all laboratories ranking the test materials in the same order with respect to toxicity. Significant differences in the absolute toxicity ratings among laboratories indicated that laboratory performance with respect to standard reference materials will be required for meaningful comparison of toxicity ratings from different laboratories.
Assessment of Biocompatibility of Orofacial Materials and Devices by Culturing with Human Excised Donor Tissues
Authors: Lontz JF , Nadijcka MD , Holmes R
Published: March 2009

Three methods for assessing biocompatibility of materials used in orofacial constructs have been studied. These methods are (1) human excised donor (HED) orofacial tissues cultured in medium containing processed human serum, (2) an established cell line cultured in a serum free medium, and (3) an established human cell line cultured in a medium containing processed human serum. Of the three methods, the first was preferred since the cells used were removed recently from their total human physiology and may provide the most realistic evaluation of human-tissue response.
The Chromium-51 Release Cytotoxicity Test: Comparison to the Agar Overlay and Cell-Growth Inhibition Tests
Authors: Magoffin DA , Kushell DL , Schlesinger RJ
Published: March 2009

The 51Cr-release assay was compared to the agar overlay and cell-growth inhibition assays for cytotoxicity. L-929 mouse fibroblasts were used in each of the three assays. Incubation of Na 51CrO4 labeled cells with increasing concentrations of phenol caused a dose-related accumulation of 51Cr in the medium. The effective dose for a 50% response ED50 was 1.1% phenol. Increasing concentrations of phenol caused a dose-related increase in cell damage as determined in the agar overlay assay (ED50 = 0.75% phenol) and a dose-dependent inhibition of cell growth (ED50 = 0.45% phenol). The sensitivity of the cell-culture methods compared favorably with the in vivo intracutaneous reactivity test in rabbits. These studies demonstrate that the 51Cr-release assay is of similar sensitivity to commonly used cell-culture cytotoxicity tests. The cell-culture tests offer better convenience and are faster and less costly than in vivo methods currently in use.
Comparisons Between Vertebrate Pest Control Materials: Essential Considerations
Authors: Salmon TP , Lickliter RE
Published: March 2009

When vertebrate pest control materials are evaluated and compared, biological, economic, and social considerations are all important. With regard to the biological and economic inputs, some of the more important points to be considered include the efficacy of materials, their usability and labor requirements, anticipated costs to users and consumers, associated hazards of each material, and the value of combining approaches when developing wildlife damage control programs. Through examples, we have demonstrated that the efficacy of any control material is a dynamic quality which varies according to season, species, locality, formulation, and use patterns, and that the interrelationship of these and other factors should be considered by decision-makers when attempting to compare the consequences of control material use, development, and regulation. We have also proposed a general outline for comparison of alternative vertebrate pest control materials.
Exploitable Characteristics of Neophobia and Food Aversions for Improvements in Rodent and Bird Control
Authors: Reidinger RF , Mason JR
Published: March 2009

Rodent and bird pests display a variety of behavioral defenses against dietary poisoning that could be exploited for improvement in control. Such defenses include neophobia, primary food aversion, and learned food aversion. Particularly with pest birds, social learning can also facilitate the transfer of learned aversions. With the rodents studied, taste appears critical for the defensive behaviors, whereas, with birds, visual or visual/taste cues appear more important.

With pest rodents, objective assessments of taste properties of rodenticides and baits could lead to improved formulations and methodology for objectively evaluating masking agents, microencapsulation, and prebaits. Assessment of the potential of a rodenticide as an unconditioned stimulus in food aversion learning, of the bait as a conditioned stimulus, and of other attributes such as generalization of learned aversions and conditioned stimulus/unconditioned stimulus intervals could lead to improved baits, baiting systems, and repellents. Weaknesses in the behaviors (for example, continuation of grooming in the presence of the defenses) might also be further exploited in rodent control.

With pest birds, Batesian mimicry probably offers advantages over food aversion learning as the conceptual basis of repellency. Use of visual cues with repellents such as methiocarb might improve aversion learning. Differential responses of the common chemical sense in birds and mammals to some compounds (such as dimethyl anthranilate) might also be used to advantage in some control situations.
A Changeover Test Design to Compare the Relative Efficacies of Bird Repellent Seed Corn Treatments
Authors: Heisterberg JF , Otis DL
Published: March 2009

A changeover test design is described in which treated seed corn was planted and the emerged sprouts were unearthed and offered in different treatment sequences on consecutive days to groups of caged birds. This design exposes each test group of birds to each seed treatment (including untreated) consecutively over time and offers a way to identify and separate any possible residual effects carried over from direct treatment effects. This design eliminates the need for birds to differentiate among treatments offered simultaneously, thus avoiding testing problems associated with the inability to differentiate between treatment areas. The test design corrects some deficiencies of previous cage and field evaluations of chemical seed treatments and has a high degree of statistical precision. The results of one evaluation with three chemical seed treatment repellents indicated that difficulties in assessing bird damage caused by confounding factors, such as uneven germination, insect and disease damage to sprouts, weather-related sprout mortality, and treatment phytotoxicity, can be eliminated by using this test design.
Use of Outdoor Pens in Evaluating Field Efficacy of Rodenticides
Authors: Daniel Ashton A , McCumber JH , Jackson WB
Published: March 2009

While laboratory efficacy testing of commensal rodenticides is essential in the development of a compound, this environment does not represent the “real world” of rodent control. Thus testing under actual-use conditions is necessary. However, such field tests may be seriously compromised by peripheral, nonexposed animals moving into an area immediately after rodenticide exposure.

When information necessary for rodenticide development, formulation, or reregistration does not warrant a full-scale field trial, a simulated field trial, using an out-door pen, may be applicable. It offers a small but restricted population of rodents [such as house mice (Mus musculus) or white-footed mice (Peromyscus leucopus)] and is less expensive.

Pen trials are confined field trials, limited in scope, subject to normal weather conditions, yet with environmental controls more akin to those of laboratory testing. Outdoor mouse pens, with harborage and food, enable introduced animals to establish a reproductively active population, which the investigator can regulate; and sensitive index methods can be utilized to monitor population density and activity.

Penned areas (about 232 m2) served as the test sites. Pen walls (aluminum sheet metal) extended 20 cm into a stone trench and 51 cm above the ground. A 1-m-wide grass strip on the interior perimeter was kept mowed to deter mice from moving near the perimeter wall. An area outside the pen also was mowed. Straw bales were placed within the pen, and grass and weeds were allowed to grow, the combination providing excellent harborage for mice.

Wild house mice released in the pen were allowed to acclimate to the surroundings for at least 30 days. Sherman live traps were placed along both sides of the pen perimeter for monitoring rodent movement into or out of the test area. Large Tomahawk live traps also were placed along the exterior pen wall to protect against ground predators.

Pens of this nature can be used for determining rodenticide efficacy, the comparative testing of rodenticides, or comparing population indexes with populations of known size. Such pens also constitute an investigative tool to study population responses to a rodenticide or bait formulation.