bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cytotoxicity Testing: Prediction of In Vivo Toxicity from In Vitro Tests
Authors: Genova TF , Bodnar S , Vaccarella M , Stafford C , Schady KM 
Published: March 2009

Tissue culture laboratories can play key roles in the development and evaluation of products. Three broad categories of materials are evaluated: new product components (polymers, fabrics, and adhesives), candidate packaging materials (papers, plastics, coatings, and inks), and existing products undergoing stability studies. Material cytotoxicity is evaluated with mouse fibroblasts (L-929) using several standardized tests: agar overlay, elution assay, and direct growth assay. The severity of specimen testing is governed by the intended use of the material. Testing severity decreases in order of the following end use categories: implantations, limited patient contact, indirect patient contact, and no patient contact.
Sample cytotoxicity is compared with that of standard, calibrated controls. Controls are formulated such that they evoke minimal responses in United States Pharmacopeia toxicity tests. Each lot of control material is certified via in vivo analysis before being used in cell culture. Control responses in vitro are then used to predict in vivo toxicity. Since the control is known to evoke a minimal in vivo response, its cell-culture response may be assumed to be equivalent to that of minimal in vivo toxicity. It is assumed that any material having a cell-culture response greater than the control will be toxic when tested in vivo. Studies are underway to further refine the correlation between in vivo and in vitro test methods.
Cell-Culture Cytotoxicity Testing of Candidate Device Materials
Authors: Meyers SG , O'Connell MB , Korczynski MS 
Published: March 2009

In vitro cytotoxicity evaluation of candidate materials for medical devices is described. Materials and material extracts are added to freshly seeded human embryonic lung fibroblast (IMR-90) cell cultures. Both negative control and positive control materials are included in each evaluation of test materials. The negative control material does not cause detectable cytotoxicity to the cell system, and the positive control material causes cytotoxic effects.
Controls are used to monitor the cell system over time and detect any changes in the system that would alter the testing results. Results are scored on the basis of degree of morphological deterioration of cells and time required to obtain maximum deterioration. Candidate materials are evaluated comparatively in terms of their relative lack of cytotoxic effects on cell culture. Final results are not interpreted on a pass/fail basis but in terms of which materials are most likely to demonstrate biocompatibility in vivo.
This paper also reviews the need to develop specific cell-culture cytotoxicity assays on the basis of the intended end use of the material being evaluated. Some historical information concerning endothelial cell-culture systems and the need to develop a standardized cytotoxicity assay for blood contact materials is reviewed.
Crack Tip Geometry for Fatigue Cracks Grown in Air and Vacuum
Authors: Bowles CQ , Schijve J 
Published: March 2009

Plastic castings of fatigue cracks were produced by a process of vacuum infiltration and subsequently examined in a scanning electron microscope. Study of the castings revealed that the crack tip geometry in the 2024-T3 and 7075-T6 alloys was essentially the same. Crack advance in air is initially “brittle” in both alloys, with the crack tip subsequently blunting to an elliptical geometry at maximum load. Brittle crack extension presumably results from tensile rupture due to the presence of water vapor. At minimum load the crack tip has been resharpened but remains generally elliptical and singly notched.
In contrast, crack advance in vacuum appears to result solely from slip activity in the absence of any active species to promote failure by tensile rupture. Crack branching is believed to be a significant means of accommodating plastic flow near the maximum of the load cycle. The crack front itself appears to be highly disorganized due to crack propagation at different levels and on different slip systems in adjacent grains of the polycrystalline materials.
Castings of air fatigued specimens also shed some new light on plasticity just behind the crack tip and on contact between the two fracture surfaces during crack closure at a larger distance behind the crack tip.
Analysis of Silvered Glass Reflectors Exposed to Controlled Environments
Authors: Masterson KD , Lind MA 
Published: March 2009

This paper describes a matrix approach to testing mirrors (MATM) for solar concentrator applications. Specimens are exposed to elevated temperatures, high humidity, ultraviolet light, thermal cycling, atmospheric pollutants, and mechanical stresses at levels greater than those encountered in natural weathering but low enough that the degradation modes are expected to be similar to those observed in naturally weathered mirrors. The degradation of mirror performance is characterized by its reflectance. Microphotography and light-scattering measurements reveal defects in the silver layer.In the initial phase of the research, specimens of commercially available wet chemical processed silver/glass mirrors were exposed for up to eight weeks at 80°C and 80 percent relative humidity (RH) and at 80 percent RH with a temperature cycle of 20 to 80 °C. A degradation in hemispherical reflectance of 15 percent and a tenfold increase in light scattering were observed for the least durable mirror types tested. The growth of defects causing light scattering is evident in the dark-field microphotography.Removing the specimens, characterizing them optically, and returning them to the chambers did not alter their degradation rates in comparison with those of the specimens left undisturbed for equivalent exposure. Specimens subjected to temperature cycling between 20 and 80 °C showed less drop in reflectance than specimens left at high temperatures for equivalent exposure periods. However, temperature cycling caused severe edge corrosion in some mirror types. The differences in degradation rates between the specimen sets enabled a rank ordering of performance to be made. The precision of all the optical measurements was much greater than the specimen-to-specimen variation in the degradation rates. Hemispherical and diffuse reflectance measurements, especially at wavelengths less than 500 nm, provide a good means for assessing the degradation of silver/glass mirrors.
Normalized Characterization Model of Pavement Materials
Authors: Baladi GY , Vallejo LE , Goiton T 
Published: March 2009

The principal objective of any pavement design procedure is to provide a structural system that will be suitable in a specific regional area and be able to sustain the anticipated traffic loading and frequency. The accomplishment of this objective and the utilization of the design procedure is highly dependent on its ability to predict future pavement performance. The success of such prediction is a function of the pavement model used and the relevancy and accuracy of its input parameters.
This paper presents and discusses the results of extensive laboratory investigations and an analytical study of permanent deformation model of several unbound materials. The developed model screens and normalizes the effects of several specimen and test variables. The model was found to be unique for each class of soil and independent of compaction, density, water content, and stress level. A significant finding of this study is that the permanent strain of any class material subjected to cyclic loading could be calculated, with high confidence level, using the developed predictive normalized model.
Characterization of Flexible Pavement: A Case Study
Authors: Baladi GY 
Published: March 2009

The degradation and the damage state of a flexible pavement section may be attributed to several factors. These include environmental factors, traffic loading factors, and material interaction and variability factors. The collective conditions of a pavement section in a particular damage state may be called pavement damage index (PDI). Such a damage index is related to the pavement deflection output.
This paper discusses the characteristic parameters of the pavement time-dependent deflection response and their relationship to the damage done to the flexible pavement section in question. Further, a case study is presented where a full-depth asphaltic highway pavement section was tested after construction and before it was subjected to any traffic loading. The calculated characteristic parameters of the time-dependent deflection response indicated, at the time, that a severe damage in the form of permanent deformations (rut depth) should be expected when the pavement section is opened to traffic. The highway section in this case study experienced a rut depth of up to 25.4 mm (1 in.) after only six months of mixed traffic (trucks and cars).
Bolt Clampup Relaxation in a Graphite/Epoxy Laminate
Authors: Shivakumar KN , Crews JH 
Published: March 2009

A simple bolted joint was analyzed to calculate bolt clampup relaxation for a graphite/epoxy (T300/5208) laminate. This study was based on a viscoelastic finite-element analysis of a double-lap joint with a steel bolt. Clampup forces were calculated for various steady-state temperature-moisture conditions using various exposure durations.
The finite-element analysis predicted that clampup forces would relax even for the room-temperature dry (RTD) condition. The relaxations were 8, 13, 20, and 31% for exposure durations of 1 day, 1 month, 1 year, and 20 years, respectively. As expected, elevated temperature and moisture levels each increased the relaxation rate. The viscoelastic effects of elevated temperature and moisture appeared to be additive.
Based on the finite-element results, a simple empirical equation was developed for clampup force relaxation. First, the equation was postulated to have the same functional form as the inverse of the material compliance in the thickness direction. Second, the two constants in the equation were fitted, by a least-square regression analysis, to the RTD results, Finally, the equation was generalized to include temperature- and moisture-dependent viscoelastic effects by using material hygrothermal shift factors. This generalized equation was used to calculate clampup forces for the same temperature-moisture conditions as used in the finite-element analysis. The two sets of calculated results agreed well.
The clampup equation was further evaluated by comparing calculated and measured clampup forces. Instrumented (strain-gaged) bolts were monitored throughout a 100-day test period. Three steady-state test environments were used: RTD, room temperature with a laboratory ambient moisture level (0.46%), and an elevated-temperature (66°C) dry case. The equation agreed reasonably well with the test data.
Data Comparability: An Objective for Precipitation Chemistry Monitoring
Authors: Jansen JJ 
Published: March 2009

Data comparability is a stated or implied goal of a number of networks today (for example, the Utility Acid Precipitation Study Program [UAPSP]). This concept is indeed very important if a research objective such as the “national objective” on precipitation chemistry monitoring is to be met using the combination of all the existing precipitation chemistry monitoring networks in North America. An analysis of the definition of data comparability shows that two steps are involved in establishing data comparability of two data sets: (1) to judge the adequacy of the data sets toward accomplishing the objective and (2) to determine the uncertainty of each data set and that of the combined data set.
Two methods are described to improve data comparability. The two methods can be represented by (1) the responsibilities of the data gatherer and (2) the responsibilities of the data analyst. In applying these methods towards meeting an example objective, it is shown that implementing and reporting quality control/quality assurance on the part of the data gatherers (that is, network operators) is the key stumbling block in the data analyst's attempts to determine the degree of data comparability. The UAPSP network is described, and the efforts to improve data comparability are discussed. The UAPSP has implemented both internal quality control and independent quality assurance to meet its responsibilities as a data gatherer. The UAPSP also sponsored a workshop in Aug. 1982 to promote discussion of ways to improve data comparability among the networks in the future.
Corncob Granules and Pelleted Carriers—New, Controlled, Safer Methods of Handling Pesticides
Authors: Vander Hooven DIB 
Published: March 2009

Uniformly graded corncob granules and finely ground corncob particles agglomerated into pelleted delivery systems are discussed.
These unique products, available in attractive commercial quantities, are described in terms of their chemical and physical constituents as well as the role they play today in agricultural chemicals. Stability data are also discussed.
Methods of applying active ingredients without the use of solvents are shown.
Altered (expanded) cob granules are shown in which the soybean oil carrying capacities have been increased from the traditional 15% to the now possible 25 to 30% loadings.
Pelleted pesticide carriers using finely ground corncob powders are shown to be safe, accurate methods of delivering active ingredients to targeted pest species.
Development of Water-Dispersible Granule Systems
Authors: Fleming JP , Hazen JL 
Published: March 2009

This paper contains an example of a typical water-dispersible granule and a description of each of the ingredients found in the formulation. The study shows that even with products in the same chemical class, slight differences can produce significant differences in the performance characteristics.
In this experiment, dispersants were investigated. Although other variables were not studied, the authors believe that differences could also be observed by changing the other ingredients—that is, the wetting agents, agglomerating agents, diluents, and so forth.
Demonstration of the Ecological Effects of Streptomycin and Malathion on Synthetic Aquatic Microcosms
Authors: Taub FB , Read PL , Kindig AC , Harrass MC , Hartmann HJ , Conquest LL , Hardy FJ , Munro PT 
Published: March 2009

Small synthetic microcosms have been developed in the authors' laboratory to provide replicate aquatic communities with interspecies competition within primary, secondary, and recycling trophic levels. The microcosms display nutrient depletion, algal competition and succession, and algal depletion through grazing and nutrient depletion. Streptomycin acted as a selective algal toxicant, reducing all indexes of primary production temporarily, and then modifying the algal dominance relationships over the 63-day experiment, although no active streptomycin could be detected by Day 28. Daphnia populations were reduced and ostracod populations markedly increased in the streptomycin-treated microcosms. These results were consistently shown in three successive microcosm experiments. In contrast, malathion caused a temporary reduction in the number of grazers and a concurrent algal bloom. Degradation of malathion was presumed from the recovery of the grazer populations, which was accompanied by the elimination of the algal bloom.
The synthetic microcosms, being composed of distilled water, silica sand, reagent-grade chemicals, and organisms that are easily reared in the laboratory, show promise of providing a nonsite specific, reproducible ecosystem-level bioassay.
Toxicity of a Complex Munitions Wastewater to Aquatic Organisms
Authors: Liu DHW , Bailey HC , Pearson JG 
Published: March 2009

The toxicity to freshwater organisms of a complex munitions effluent called condensate wastewater was determined using a novel and relatively economical approach proposed by Pearson and co-workers at the Second Annual ASTM Symposium on Aquatic Toxicology. Applicable only to complex wastewaters in which the concentrations of the individual chemical components are relatively constant over time, the approach emphasizes performing toxicity and related tests on a chemical mixture representative of the actual wastewater, with secondary attention being directed toward testing the individual chemical components, which is the conventional approach. The testing program comprised several series of static acute toxicity tests on authentic wastewater, artificial wastewater, and selected components to identify the conditions under which they are most toxic and to identify the most sensitive species; a series of flow-through acute toxicity tests on the artificial wastewater using the most sensitive species; a series of short-term bioconcentration tests; several early life-stage tests; and, finally, several life-cycle chronic tests. Twelve species representing three trophic levels were employed in the program.
It was concluded that the approach economically and rapidly provided a sufficient data base for assessing the effects of the wastewater on aquatic life. Two modifications were recommended to decrease the cost and time of obtaining the data. One was to perform a static and a flow-through test early in the testing program to identify the most appropriate exposure condition to use in the initial portion of the program. The other was to compute the octanol-water partition coefficients of the organic components of the wastewater before performing any bioconcentration test and to use the coefficients to determine if bioconcentration tests are necessary.
Leach Testing of Foundry Process Wastes
Authors: Boyle WC , Ham RK , Pastene J , Stanforth R 
Published: March 2009

Emission control dusts, sludges, and mixed foundry process wastes were sampled from 21 foundries in Michigan and Pennsylvania and subjected to the pH 5 acetic acid extraction procedure (EP) specified by the U.S. Environmental Protection Agency (EPA) under the Resource Conservation and Recovery Act (RCRA) to define whether a waste is hazardous. This was in accordance with EPA's concern about cadmium, chromium, and lead extractions from such wastes. In addition, distilled water extractions were performed on all wastes, and controlled pH extractions ranging from pH 4 to 8 were performed on selected wastes. Finally, total metal contents were obtained to determine the percentages of the three metals extracted.
Emission control dusts and sludges from 9 of the 21 foundries were found to be EP toxic with respect to cadmium or lead or both. None were chromium toxic. Extraction was highly pH dependent, with much lower concentrations obtained at higher pH levels. Distilled water extractions resulted in one emission control waste being classified as EP toxic. Mixing emission control wastes with other process wastes resulted in a mixture much less likely to be classified EP toxic from that foundry.
The percentages of metals released in the EP test ranged from basically zero to 39% for cadmium, &lt;1 to 12% for lead, and basically zero to 0.5% for chromium.
Testing Procedure for Evaluating Codisposal of Industrial Wastes and Municipal Refuse with Particular Reference to Pesticides
Authors: Stevens C , Jenkins DKW , Wilson DC 
Published: March 2009

For a number of years, the Waste Research Unit of the Harwell Laboratory has been conducting research on the codisposal of industrial waste and municipal refuse as a practical and environmentally acceptable disposal option. Codisposal depends on utilizing the attenuation capacity of the refuse, and involves mechanisms such as dilution, biodegradation, adsorption, and precipitation.
To make a closer comparison with a codisposal site, laboratory-scale landfill experiments have been designed with the aim of studying the behavior of pesticide wastes. Four pesticides were selected for investigation, namely lindane, pirimiphos-methyl, (4-chloro-2-methylphenoxy) acetic acid (MCPA), and atrazine. Leachate monitoring revealed that the migration of MCPA, atrazine, and pirimiphos-methyl through municipal wastes was closely related to their solubility in water. The results for lindane are not yet available. The attenuative capacity of the refuse was investigated by comparing the concentration of pesticide in leachate immediately below the layer of pesticide waste and at the base of the column. Significant attenuation of MCPA and atrazine was observed.
The use of destructive sampling produced additional information in relation to attenuation, the effect on landfill microflora, and persistence of the pesticides under landfill conditions. The marked persistence of pirimiphos-methyl, a pesticide normally considered to be short-lived under agricultural conditions, illustrates that predictions based on extrapolation from agrarian practice are misleading. The results emphasize the importance of laboratory-scale experiments in the study of landfill science.
Development of a Solvent Extraction Method for Determining Semivolatile Organic Compounds in Solid Wastes
Authors: Warner JS , Landes MC , Slivon LE 
Published: March 2009

This study was undertaken to develop an improved method for determining the total content of individual semivolatile organic compounds in solid wastes. The requirements of the method are as follows: applicable to a wide range of specimen matrixes; applicable to a wide range of compounds; quantification range of 1 ppm to 100%; acceptable recovery and reproducibility; and easily performed at reasonable cost.
The waste matrixes of interest include aqueous sludges, dry solids, soils, tars, oils, and oily sludges. The compounds of interest include aromatic halocarbons, aromatic hydrocarbons, aromatic nitro compounds, chlorinated pesticides, phosphates esters, halogenated ethers, phenols, anilines, quinolines, and other extractable organic compounds having boiling points in the range of 150 to 500°C.
The method developed is a dry neutral extraction procedure that involves a single extraction with methylene chloride under neutral conditions with anhydrous sodium sulfate added to remove any water present. Sonification with a high-intensity sonic probe is used to promote the interaction of the extraction solvent with the waste. Screening steps are incorporated into the method to determine the neutralization requirement of the specimen, the residue weight of the extract, and the optimum concentration of the extract for subsequent analysis. Gas chromatography-mass spectrometry (GC-MS) analysis using a fused silica capillary column is used to analyze the extract.
The dry neutral extraction method shows promise in meeting the requirements specified. The estimated quantification limit is 1 ppm for specimens that contain up to 1 mg/g of solvent extractable material and proportionately higher for other specimens. The mild extraction conditions used mimimize any losses from chemical reactivity. No emulsion or phase separation problems are encountered. The use of a single extraction under neutral conditions as employed in the method has been shown to be suitable for the extraction of a wide variety of compounds including phenols, anilines, and neutral compounds.